JP4673655B2 - Light emitting device and image forming apparatus - Google Patents

Description

  The present invention relates to a light emitting device and an image forming apparatus.

  FIG. 26 is a circuit diagram showing a schematic circuit configuration of a basic structure of a conventional light emitting device 1 having a self-scanning function. The light-emitting device 1 includes a switch thyristor array 4 in which switch thyristors T1, T2,..., Tn-1, Tn are arranged substantially linearly, and light-emitting thyristors L1, L2,. And a light emitting thyristor array 5 arranged in a substantially straight line. When the switch thyristors T1, T2,..., Tn−1, Tn are collectively referred to, they are simply referred to as switch thyristors T, and when the light emitting thyristors L1, L2,. May be described.

In the light emitting device 1, among the switch thyristors T1, T2, ..., Tn-1, Tn and the light emitting thyristors L1, L2, ..., Ln-1, Ln, the corresponding gates of the switch thyristors T and the light emitting thyristors L The gate is connected. For example, the switch thyristor Tn arranged nth from the upstream side in the scanning direction is connected to the gate of the light emitting thyristor Ln arranged nth from the upstream side in the scanning direction. The gate of the switch thyristor T1 is connected to the first signal input line S. The gate of each switch thyristor T is connected to the control power supply V _GK via the load resistor _RL , and two transfer clock lines CL1 and CL2 are repeated for each of the two switch thyristors on the anode electrode. Connected. For example, the switch thyristors T1 and T3 are connected to the clock line CL2. For example, the switch thyristors T2 and T4 are connected to the transfer clock line CL1.

  Further, the gate of the switch thyristor T2, the gate of the switch thyristor T1, and the transfer direction designation diode D are connected, and thereafter the gates of the adjacent switch thyristors T are similarly connected via the transfer direction designation diode D. . The transfer direction designating diode D has an anode connected to the gate of the switch thyristor on the downstream side in the transfer direction. The anode of the light emitting thyristor L is connected to the second signal input line E, and the cathode is grounded.

  FIG. 27 is a waveform diagram for explaining the operation of the light-emitting device 1. In FIG. 27, φS represents a start pulse applied to the first signal input line S, φ1 and φ2 represent first and second clock pulses applied to the transfer clock lines CL1 and CL2, respectively, and φE represents the first pulse. The light emission clock pulse applied to the two-signal input line E is represented, and L represents the light emission intensity of the light emission thyristor T1.

  The transfer starts when the start pulse φS changes from the high level to the low level. As a result, the threshold voltage of the switch thyristor T1 is electrically reduced. At this time, the switch thyristor T1 is turned on by changing the second clock pulse φ2 from the low level to the high level. In the switch thyristor T on the downstream side of the switch thyristor T2, the voltage applied to the gate of the switch thyristor T increases by the forward voltage drop of the diode D as the distance from the switch thyristor T1 increases. For this reason, since the gate of the switch thyristor T3 to which the same transfer clock line CL2 is connected is connected to the gate of the switch thyristor T1 via two diodes D, the threshold voltage of the switch thyristor T3 is the switch thyristor T1. By giving a start pulse that the threshold voltage of the diode D is increased by two voltages from the gate of the transistor D2, and the high level of the second clock pulse φ2 is less than or equal to the threshold voltage of the switch thyristor T3, Only the switch thyristor T1 is turned on.

  When the light emission clock pulse φE is changed from the low level to the high level in this state, the on condition of the light emitting thyristor L1 whose gate is connected to the gate of the switch thyristor T1 becomes the same as the on condition of the switch thyristor T1. L1 is lit. By returning the light emission clock pulse φE from the high level to the low level, the light emission thyristor L1 is turned off and turned off.

  Next, on-state transfer from the switch thyristor T1 to the switch thyristor T2 will be described. If the second clock pulse φ2 remains at a high level even when the light emitting thyristor L1 is turned off, the on state of the switch thyristor T1 is maintained. At this time, in the switch thyristor T2, the voltage applied to the gate is higher by one diode D than in the light emitting thyristor T1, and the switch thyristor T4 to which the same transfer clock line CL1 is connected has two more diodes D. The voltage applied to the gate increases by the amount. In this state, when the first clock pulse φ1 is changed from the low level to the high level, the first clock pulse φ1 is set so as to be between the threshold voltage of the switch thyristor T2 and the threshold voltage of the switch thyristor T4. If the high level is selected, only the switch thyristor T2 is turned on.

After the switch thyristor T2 is turned on, the switch thyristor T1 is turned off similarly to the light emitting thyristor L1 being turned off by changing the second clock pulse φ2 from the high level to the low level. At this time, since the start pulse φS changes from the low level to the high level, the voltage applied to the gate of the switch thyristor T1 by the transfer direction designation diode D becomes substantially equal to the voltage of the control power supply V _GK , Among the switch thyristors T, the threshold voltage of the switch thyristor T2 is the lowest. In this way, the ON state of the switch thyristor T moves from the switch thyristor T1 to the switch thyristor T2. At this time, when the light emission clock pulse φE is changed from the low level to the high level, the light emission thyristor L2 is turned on to emit light.

  By sequentially repeating the above operation in the switch thyristors T1, T2,..., Tn−1, Tn, the ON state of the switch thyristor T is sequentially transferred, and the light emitting thyristor L can selectively emit light with fewer wires. (For example, see Patent Documents 1 to 5).

  FIG. 28 is a plan view of the light emitting chip 2 constituting the light emitting device 1. In the light emitting device 1, a light emitting chip 2 that is a semiconductor chip in which a predetermined number of light emitting thyristors L and a predetermined number of switch thyristors T are integrated is configured, and the light emitting thyristor L and the switch thyristor T are driven on the light emitting chip 2. Bonding pads 3 are formed for supplying signals necessary for the above operation to each clock line CL.

The light emitting device 1 has bonding pads 3 to which clock lines CL1 and CL2, first and second signal input lines S and E, and a control power source V _GK are connected. Since the light emitting device 1 requires several bonding pads 3 for one light emitting chip 2, the bonding pad 3 is used as a switch thyristor of the light emitting chip 2 for the purpose of reducing the short side length of the light emitting chip 2. The array 4 and the light-emitting thyristor array 5 are formed outside the region where the switch thyristor array 4 and the light-emitting thyristor array 5 are formed, at one end or both ends in the arrangement direction of the array 4 and the light-emitting thyristor array 5. , See Patent Document 5).

  A plurality of the light emitting chips 2 described above are arranged to form a linear light source of a predetermined size. FIG. 29 is a plan view showing an arrangement state when a plurality of light emitting devices 1 are used as linear light sources. When the light-emitting device 1 is used as a linear light source, a plurality of light-emitting chips 2 are arranged at equal intervals so as to face two lines, and the two light-emitting chip arrays are parallel and arranged in a light-emitting thyristor array. They are arranged in a zigzag pattern with a predetermined interval between the five. When the light emitting chips 2 are arranged in a line, the light emitting thyristor L is spaced by the space of the bonding pad 3 formed at the end of the light emitting chip 2 in the arrangement direction. It is necessary to arrange two rows of light emitting chip rows in parallel and at equal intervals.

Japanese Patent No. 2577034 Japanese Patent No. 2577089 Japanese Patent No. 2683781 JP 2003-243696 A Japanese Patent No. 3224337

  In the conventional light emitting device 1 described above, when a plurality of light emitting chips 2 are used to form a linear light source, the light emitting chips 2 adjacent to each other by the space of the bonding pad 3 are arranged when the light emitting chips 2 are arranged in one row. Since there is a gap between the elements L, in order to arrange the light emitting elements L of the adjacent light emitting chips 2 close to each other, it is essential to arrange the light emitting chips in parallel and at equal intervals in two rows. Compared with the case where the light emitting chips are arranged in one row, the manufacturing process becomes complicated.

  Further, when the light emitting chip 2 is manufactured, the light emitting chip L is cut out from a wafer which is a precursor of the light emitting chip 2, and the light emitting element L is extended along the long side portion of the light emitting chip 2. Therefore, when the light emitting chip 2 is cut out, the light emitting element L is easily damaged and diced so as not to cause chipping, or lapping is performed after the cutting. It must be added and is inferior in productivity.

  Further, when the light emitting chips 2 are arrayed and used as an exposure device of the image forming apparatus, the light emitting chips 2 need to be arranged in two rows. Therefore, exposure to the photosensitive drum via the lens array is performed for each row of the light emitting chips 2. There is a problem in that the optical axis shifts and the image quality deteriorates. Further, when the photosensitive drum is exposed, the light-emitting chips 2 arranged oddly and the light-emitting chips 2 arranged evenly along the arrangement direction are different in writing lines. It is necessary to read at a time, and a memory function for storing line data in the light emitting device 1 is required.

  Therefore, an object of the present invention is to selectively emit a plurality of light emitting elements arranged with as few signal transmission paths as possible without complicating the structure of the apparatus, and to use a plurality of light emitting elements side by side. It is an object of the present invention to provide a light-emitting device in which light-emitting elements can be arranged in a line and the productivity is improved, and an image forming apparatus including the same.

The present invention has a plurality of light emitting elements which emit light when a trigger signal is optically or electrically applied to a predetermined portion and a light emission signal is applied, and the plurality of light emitting elements are arranged at intervals. A light emitting element array,
A light emission signal transmission path that is connected to each of the light emitting elements and transmits the light emission signal;
In response to the scanning signal, each of the corresponding light emitting elements has a plurality of switch elements that give a trigger signal to the predetermined portion, and each switch element is optically connected to the corresponding light emitting element in a state of facing the plurality of light emitting elements. or together are electrically connectable, the switch elements are arranged divided to one side and the other side of the light emitting element array in sequence direction of the light emitting elements, sites predetermined switching elements adjacent to each other A plurality of switch element arrays that are optically or electrically connected;
A plurality of scanning signal transmission paths that are connected to each switch element of the switch element array and transmit scanning signals given at different timings for each switch element adjacent in the arrangement direction;
Provided along the light emitting element array in a region adjacent to the arrangement direction of each switch element array, the light emitting signal transmission path and the external signal transmission path, and the scanning signal transmission path and the external signal transmission A signal transmission path connection section for individually connecting the paths,
A light-emitting device including a light-emitting element light-shielding portion that is provided between the light-emitting elements and shields light from the light-emitting elements toward the arrangement direction.

  In the invention, it is preferable that the signal transmission line connection portion is a bonding pad.

  In the invention, it is preferable that the signal transmission line connecting portion is formed at a predetermined distance from an end portion of the light emitting element array in a direction perpendicular to the arrangement direction.

  In addition, the present invention is a light emitting device comprising a plurality of the light emitting devices and configured by linearly arranging the light emitting elements of each light emitting device.

The present invention also provides the light emitting device;
Driving means for driving the light emitting device based on image information;
Condensing means for condensing the light from the light emitting element of the light emitting device on the charged photosensitive drum;
And light developer supply means for supplying a developer to the photosensitive drum which is exposed is focused on the photosensitive drum by said focusing means from the light emitting device,
Transfer means for transferring an image formed by the developer supplied to the photosensitive drum by the developer supply means to a recording sheet;
An image forming apparatus comprising: a fixing unit that fixes the developer transferred to the recording sheet by the transfer unit .

  According to the present invention, each switch element of the switch element array is configured such that one switch element is in a light emitting state or a conductive state by optically or electrically connecting predetermined portions of adjacent switch elements. When at least one of them, the threshold voltage or threshold current of the adjacent switch element is lowered, and the scanning signal transmitted by the scanning signal transmission line connected to the switch element having the lowered threshold voltage or threshold current is reduced. By being applied, the switch element in which the threshold voltage or the threshold current has been lowered becomes at least one of a light emitting state and a conductive state. Since the scanning signals transmitted by the plurality of scanning signal transmission paths are given at different timings for each light emitting switch element adjacent in the arrangement direction, the scanning signal is applied to the light emitting switch element whose threshold voltage or threshold current has decreased. Accordingly, the light emitting switch elements can be sequentially brought into at least one of a light emitting state and a conductive state in the arrangement direction.

  In response to the scanning signal, the switch element applies a trigger signal to the predetermined portion of each corresponding light emitting element, and the light emitting element is supplied with the trigger signal at the predetermined portion, and the light emission to which the trigger element is applied. Each light emitting element can be made to emit light selectively by giving the element a light emission signal transmitted through the light emission signal transmission path.

Each switch element array is disposed so as to divide the one side and the other side of the light emitting element array in sequence Direction of each light emitting element, a region adjacent to the arrangement direction of the switching element array, along the light-emitting element array Since the signal transmission path connection portion is provided, the end of the light emitting element array in the arrangement direction of the light emitting elements can be arranged at the end of the light emitting device, and the light emitting element array in the direction perpendicular to the arrangement direction. When the signal transmission line connection portion is provided on one side and the other side, the size of the light emitting device in the direction perpendicular to the arrangement direction can be made as small as possible.

Therefore, when a plurality of light emitting devices are used by arranging the light emitting element arrays in the arrangement direction, the light emitting elements of the adjacent light emitting devices are arranged as much as possible by arranging the light emitting elements at the ends of the light emitting devices in the arrangement direction. Even if the light emitting devices are arranged in a line, the space between the light emitting element arrays can be within a predetermined range, so that it is not necessary to arrange the light emitting devices in a staggered manner, and the process can be simplified.
Further, by forming the light-emitting element light-shielding portion, it is possible to prevent this light from being received when the adjacent light-emitting element emits light. Since the threshold voltage or threshold current does not change, the light emitting element can selectively and stably emit light.

  According to the present invention, the signal transmission line connection portion is realized by the bonding pad. An external signal transmission path can be connected to the bonding pad, for example, by wire bonding.

  According to the present invention, a light emitting device is formed by arranging a plurality of light emitting devices and linearly arranging the light emitting elements of each light emitting device. When the light emitting element array is used side by side in the arrangement direction, the light emitting elements can be arranged as close as possible to the light emitting elements of the adjacent light emitting devices by arranging the light emitting elements at the ends of the light emitting devices in the arrangement direction. Even if they are arranged in one row, the space between the light emitting element arrays can be within a predetermined range, so that it is not necessary to arrange the light emitting devices in a staggered manner, and the process can be simplified.

  According to the present invention, the photosensitive drum is exposed by driving the light emitting device by the driving unit based on the image information and condensing the light from the light emitting device on the charged photosensitive drum by the condensing unit. An electrostatic latent image is formed on the surface. When the developer is supplied to the photosensitive drum on which the electrostatic latent image is formed by the developer supplying means, the developer adheres to the photosensitive drum and an image is formed. An image formed with the developer on the photosensitive drum is transferred to the recording sheet by the transfer unit, and the developer transferred to the recording sheet is fixed by the fixing unit, whereby an image is formed on the recording sheet.

  The light emitting switch element emits light in order along the scanning direction. However, since the photosensitive drum is exposed by the light emission of the light emitting element, the photosensitive drum is not exposed by the light emission of the light emitting switch element. High quality recorded images can be obtained.

  In addition, the light-emitting element for exposing the photosensitive drum and the switch element for signal transfer can be integrated so that the circuit board for mounting the light-emitting device can be downsized. In addition, since the number of wire bondings with the circuit board and the number of drive ICs to be mounted on the circuit board can be reduced, downsizing and cost reduction can be realized.

  FIG. 1 is a partial plan view showing a basic configuration of a light-emitting device 10 according to a first embodiment of the present invention. The figure shows the plane of the light emitting device 10 arranged with the light emitting direction of each light emitting element L as the front side perpendicular to the paper surface. The light emitting signal transmission path 12, the scanning signal transmission path 15, and the start signal transmission path 16 are shown. The gate 19 of the light emitting element, the gate 24 of the switching element, the gate 26 of the scanning start switching element, the connecting means 14, the light emitting element light-shielding portion 23, and the surface electrode 25 are shown by hatching for ease of illustration. ing.

  The light emitting device 10 includes a light emitting element array 11, a light emission signal transmission path 12, a switch element array 13, a connection means 14, first to third scanning signal transmission paths 15a, 15b, and 15c, and a scan start switch element. T0, the start signal transmission line 16, the insulating layer 17, the light shielding layer 18, and the light emitting element light shielding part 23 are comprised. An optical scanning switch device is configured including the switch element array 13, the first to third scanning signal transmission paths 15 a, 15 b, 15 c, and driving means 73.

  The light emitting element array 11 includes a plurality of light emitting elements L1, L2,..., Li-1, Li (the symbol i is a positive integer of 2 or more), and each light emitting element L1, L2,. 1, Li are arranged at a distance W1 from each other. Hereinafter, when the light emitting elements L1, L2,..., Li-1, Li are collectively referred to, and when an unspecified one among the light emitting elements L1, L2,. May be described. The light emitting element L is a light emitting element for exposure. In the present embodiment, the light emitting elements L are arranged at regular intervals and in a straight line. The arrangement direction X of the light emitting elements L is the left-right direction in FIG. Hereinafter, the arrangement direction X of the light emitting elements L may be simply referred to as the arrangement direction X. A direction along the light emission direction of each light emitting element L is defined as a thickness direction Z, and a direction perpendicular to the arrangement direction X and the thickness direction Z is defined as a width direction Y. The light emitting element L is formed so as to emit light having a wavelength of 600 nm to 800 nm.

  The light emitting element L is realized by a light emitting thyristor having a PNPN structure configured by alternately stacking P-type semiconductor layers and N-type semiconductor layers. The light emitting element L has a negative resistance characteristic similar to that of the reverse blocking three-terminal thyristor. The light emitting element L has a threshold voltage lower than the voltage of the light emission signal φE by giving a trigger signal to the gate 19 which is a predetermined portion, and when the light emission signal φE is given, or the current of the light emission signal φE When the threshold current is lowered and the light emission signal φE is given, light is emitted. The voltage of the light emission signal φE is a voltage applied between the anode and the cathode of the light emitting element L when the light emission signal φE is given, and the current of the light emission signal φE is light emission when the light emission signal φE is given. This is a current applied to the element L.

  The interval W1 between the light emitting elements L in the arrangement direction X and the length W2 of the light emitting elements L in the arrangement direction X are determined by the resolution of an image to be formed in an image forming apparatus 87 described later on which the light emitting device 10 is mounted. For example, when the resolution of the image is 600 dots per inch (dpi), the interval W1 is selected to be about 24 μm (micrometer), and the length W2 is selected to be about 18 μm. The length W2 is selected so that the light emitting element light-shielding portion 23 can be formed between the adjacent light emitting elements L. The dimension in the arrangement direction X of the light emitting elements L is selected to be smaller than the dimension in the width direction Y of the light emitting elements L. This prevents the light amount of the light emitting elements L from being insufficient when the light emitting elements L are brought close to each other in the arrangement direction X to increase the integration density.

  The light emission signal transmission path 12 is connected to each light emitting element L, and transmits the light emission signal φE to each light emitting element L. The light emission signal transmission path 12 is formed by a conductive material such as a metal material or an alloy material so as to reflect light having a wavelength emitted from the light emitting element L. Specifically, the light emission signal transmission path 12 is formed of gold (Au), an alloy of gold and germanium (AuGe), an alloy of gold and zinc (AuZn), nickel (Ni), aluminum (Al), or the like. .

  The light emitting signal transmission path 12 is adjacent to the width direction Y of each light emitting element L, and the signal path extending portion 21 extending along the light emitting element array 11 and the signal path extending at an interval in the arrangement direction X. It has the element connection part 22 which protrudes in the width direction one Y1 from the existing part 21, and is connected to the thickness direction one end part of each light emitting element L. FIG.

  The switch element array 13 includes a plurality of switch elements T1, T2,..., Tj-1, Tj (the symbol j is a positive integer of 2 or more), and each switch element T1, T2,. 1 and Tj are arranged at an interval W3 so as to receive light from adjacent switch elements T1, T2,..., Tj−1, Tj. Hereinafter, when the switch elements T1, T2,..., Tj-1, Tj are collectively referred to and when an unspecified one of the switch elements T1, T2,. May be described. The switch element T is a light emitting switch element, in other words, a light emitting element for switching. In the present embodiment, the switch elements T are arranged at equal intervals. Each switch element T is adjacent to the light emitting element array 11 in the width direction Y, and is arranged linearly along the light emitting element array 11 so as to face the plurality of light emitting elements L. Therefore, the arrangement direction of the switch elements is the same as the arrangement direction X of the light emitting elements L. The dimension in the arrangement direction X of the switch elements T is selected to be smaller than the dimension in the width direction Y of the switch elements T. Thus, when the switch elements T are brought close to each other in the arrangement direction X and the integration density is increased, it is possible to prevent the switch elements T from being insufficient in light quantity.

  The switch element T is realized by a light-emitting thyristor having a PNPN structure configured by alternately stacking P-type semiconductor layers and N-type semiconductor layers. The switch element T has a negative resistance characteristic similar to that of the reverse blocking three-terminal thyristor. The switch element T generates a trigger signal at the gate 24 which is a predetermined part by light reception, the threshold voltage is lower than the voltage of the scanning signal φ given through the scanning signal transmission path 15, and the scanning signal φ Is emitted, or when the threshold current is lower than the current of the scanning signal φ and the scanning signal φ is applied, light is emitted. The voltage of the scanning signal φ is a voltage applied between the anode and the cathode of the switch element T when the scanning signal φ is given, and the current of the scanning signal φ is a switch when the scanning signal φ is given. This is a current applied to the element T.

  In the present embodiment, the numbers of light emitting elements L and switch elements T are equal, i.e., i and symbol j are selected to be equal.

  Since the interval W3 between the switch elements T in the arrangement direction X is limited in the manufacturing process, it is formed at least twice the height in the thickness direction Z of the switch elements T, but is selected to be less than 20 μm, preferably 10 μm. Selected below. In the present embodiment, the height of the switch element T is about 4 μm, and in this case, the interval W3 is about 8 μm. When the interval W3 is 20 μm or more, the transmission efficiency is greatly reduced.

  The length W4 in the arrangement direction X of the switch elements T is defined as the interval W1 between the light emitting elements L in the arrangement direction X, the length W2 in the arrangement direction X of the light emitting elements L, and the interval between the switch elements T in the arrangement direction X. And W3. That is, the length obtained by adding the interval W1 between the light emitting elements L in the arrangement direction X and the length W2 in the arrangement direction X of the light emitting elements L, the interval W3 between the switch elements T in the arrangement direction X, and the arrangement direction of the switch elements T The length obtained by adding the length W4 of X is selected equally.

  The connection means 14 electrically connects the gate 19 which is the predetermined portion of each light emitting element L and the gate 24 which is the predetermined portion of each switch element T corresponding to each light emitting element L. Specifically, the connecting means 14 electrically connects the gate 19 of the light emitting element L1 and the gate 24 of the switch element T1, and electrically connects the gate 19 of the light emitting element L2 and the gate 24 of the switch element T2. The gate 19 of the light emitting element Li-1 and the gate 24 of the switch element Tj-1 are electrically connected, and the gate 19 of the light emitting element Li and the gate 24 of the switch element Tj are electrically connected. Connect individually.

  The connection means 14 is realized by a conductive path formed of a conductive material such as a metal material and an alloy material. Specifically, the connecting means 14 is formed of gold (Au), an alloy of gold and germanium (AuGe), an alloy of gold and zinc (AuZn), nickel (Ni), aluminum (Al), or the like.

  The first, second, and third scanning signal transmission paths 15a, 15b, and 15c are connected to each switch element T, and are provided at different timings for each switch element T adjacent in the arrangement direction X. Scan signals φ1 to φ3 are transmitted. In the present embodiment, the first scanning signal transmission path 15a transmits the first scanning signal φ1, the second scanning signal transmission path 15b transmits the second scanning signal φ2, and the third scanning signal transmission path 15c The third scanning signal φ3 is transmitted. When generically referring to the first, second and third scanning signal transmission lines 15a, 15b and 15c, and when indicating an unspecified one among the first, second and third scanning signal transmission lines 15a, 15b and 15c, When it is simply described as the scanning signal transmission line 15 and generically refers to the first to third scanning signals φ1, φ2, and φ3, and when it indicates an unspecified one among the first to third scanning signals φ1, φ2, and φ3, In some cases, it is simply described as a scanning signal φ. The scanning signal transmission path 15 is formed of gold (Au), an alloy of gold and germanium (AuGe), an alloy of gold and zinc (AuZn), nickel (Ni), aluminum (Al), or the like.

  The first, second, and third scanning signal transmission paths 15a, 15b, and 15c are formed so as to overlap each switch element T through the insulating layer 17 in one thickness direction Z1 of each switch element T, and along the arrangement direction X. Extend. The first, second and third scanning signal transmission paths 15a, 15b and 15c are arranged with a predetermined interval W5 in the width direction Y. The predetermined interval W5 is selected as a distance that does not cause a short circuit between the first, second, and third scanning signal transmission paths 15a, 15b, and 15c, and is selected to be 10 μm, for example.

  Each switch element T has a surface electrode 25 on one end in the thickness direction Z1, that is, on the front side in the direction perpendicular to the paper surface of FIG. The first, second, and third scanning signal transmission paths 15a, 15b, and 15c are sequentially connected to the surface electrode 25 of each switch element T one by one, and three each along the arranged switch elements T. Every other switch element T is connected. That is, the first scanning signal transmission path 15a is connected to the switch elements T1, T4,..., Tj-2 (the symbol j is an integer and 3 × m, and the symbol m is a natural number), and the second scanning signal transmission path. 15b is connected to the switch elements T2, T5,..., Tj-1, and the third scanning signal transmission path 15c is connected to the switch elements T3, T6,. Therefore, among the switch elements T, the switch element Tn arranged at the nth position in the arrangement direction X (the symbol n is a positive integer that is 2 or more and j or less) and the switch element Tn in the arrangement direction one adjacent to the X1 side. The switch element Tn−1 to be connected and the switch element Tn + 1 adjacent to the other X2 side in the arrangement direction of the switch element Tn are connected to different scanning signal transmission paths 15, respectively.

  The scanning start switch element T0 is realized by a light emitting thyristor having a PNPN structure in which P-type semiconductor layers and N-type semiconductor layers are alternately stacked. The scan start switch element T0 has a negative resistance characteristic similar to that of the reverse blocking three-terminal thyristor. The scanning start switch element T0 has a threshold voltage lower than the voltage of the scanning signal φ by applying a trigger signal to the gate 26 which is a predetermined portion, and when the scanning signal φ is applied, or the scanning signal φ Emits light when the threshold current is lower than the current and the scanning signal φ is applied.

  The scanning start switch element T0 is disposed so as to irradiate the switch element T disposed at the end of the switch element array 13 in the arrangement direction X with light. In the present embodiment, the scanning start switch element T0 is arranged to irradiate the switch element T1 with light. Therefore, one of the arrangement directions X1 in which the scanning start switch element T0 is arranged is the upstream side of the light scanning direction in the optical scanning device.

  The start signal transmission path 16 is connected to the gate 26 of the scanning start switch element T0, and transmits a start signal φS serving as a trigger signal to the scanning start switch element T0. The start signal transmission line 16 is formed of a conductive material such as a metal material and an alloy material. Specifically, the start signal transmission path 16 is formed of gold (Au), an alloy of gold and germanium (AuGe), an alloy of gold and zinc (AuZn), nickel (Ni), aluminum (Al), or the like. .

  The light emitting element L, the switch element T, and the scan start switch element T0 described above are covered with the insulating layer 17.

  The light shielding layer 18 covers each switch element T from one side in the thickness direction Z of each switch element T, that is, from the front side perpendicular to the paper surface of FIG. The light emitted from the switch element T is shielded so that the light emitted from T does not interfere.

  The light-emitting element light-shielding portions 23 are provided between the light-emitting elements L and outside the light-emitting element L in the arrangement direction X at both ends of the light-emitting element array 11 in the arrangement direction X. Block the light that goes. The light emitting element light shielding portion 23 is provided apart from the light emission signal transmission path 12 and is electrically insulated from the light emission signal transmission path 12 by the insulating layer 17.

  The light emitting element L, the light emitting signal transmission path 12, the switch element T, the connecting means 14, the scanning signal transmission path 15, the scanning start switch element T0, the start signal transmission path 16, the insulating layer 17, the light shielding layer 18, and the light emitting element light shielding. The unit 23 is formed by being integrated on one substrate 31.

Hereinafter, each configuration of the light emitting device 10 will be described more specifically.
FIG. 2 is a partial cross-sectional view showing the basic configuration of the light emitting device 10 as viewed from the section line A1-A1 of FIG. The light emitting element L includes a first one-conductivity-type semiconductor layer 32, a first other-conductivity-type semiconductor layer 33, a second one-conductivity-type semiconductor layer 34, and the first one-conductivity-type semiconductor layer 34 formed on one surface 31a in the thickness direction Z of the substrate 31. A second other conductivity type semiconductor layer 35 is included.

  The substrate 31 is a one-conductivity type semiconductor substrate in the present embodiment. On the other surface 31b in the thickness direction Z of the substrate 31, a back electrode 36 is formed. The back electrode 36 is formed over the entire surface of the other surface 31 b in the thickness direction Z of the substrate 31. The back electrode 36 is formed of a conductive material such as a metal material and an alloy material. Specifically, the back electrode 36 is made of gold (Au), an alloy of gold and germanium (AuGe), an alloy of gold and zinc (AuZn), or the like. One surface 31a of the thickness direction Z of the substrate 31 is formed in a plane.

  In the light emitting element L, a first one-conductivity-type semiconductor layer 32 is stacked on one surface 31a in the thickness direction Z of the substrate 31, and the first one-conductivity-type semiconductor layer 32 has a first surface 32a on the one surface 32a. The first other conductivity type semiconductor layer 33 is laminated, the second one conductivity type semiconductor layer 34 is laminated on the one surface 33a of the first other conductivity type semiconductor layer 33 in the thickness direction Z, and the second one conductivity type. A second other conductivity type semiconductor layer 35 is stacked on one surface 34 a of the semiconductor layer 34 in the thickness direction Z, and an ohmic contact layer 37 is formed on the one surface 35 a of the second other conductivity type semiconductor layer 35 in the thickness direction Z. It is constructed by stacking.

  More specifically, the substrate 1 is a semiconductor substrate capable of crystal growth, such as a III-V group compound semiconductor layer and a II-VI group compound semiconductor layer, such as gallium arsenide (GaAs) or indium phosphide (InP). , Gallium phosphide (GaP), silicon (Si), germanium (Ge) and other semiconductor materials.

The first one-conductivity-type semiconductor layer 32 is formed of a semiconductor material such as gallium arsenide (GaAs), aluminum gallium arsenide (AlGaAs), or indium gallium phosphide (InGaP). The carrier density of the first one-conductivity-type semiconductor layer 32 is preferably about 1 × 10 ¹⁸ cm ⁻³ .

The first other conductivity type semiconductor layer 33 is formed of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs). The semiconductor material forming the first other-conductivity-type semiconductor layer 33 is formed with the same energy gap as the semiconductor material forming the first one-conductivity-type semiconductor layer 32 or the first one-conductivity-type semiconductor layer 32. A material having an energy gap smaller than that of the semiconductor material is selected. The carrier density of the first other conductivity type semiconductor layer 33 is desirably about 1 × 10 ¹⁷ cm ⁻³ .

The second one-conductivity-type semiconductor layer 34 is formed of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs). The semiconductor material for forming the second one-conductivity-type semiconductor layer 34 is formed with the same energy gap as the semiconductor material for forming the first other-conductivity-type semiconductor layer 33 or the first other-conductivity-type semiconductor layer 33. A material having an energy gap smaller than that of the semiconductor material is selected. The carrier density of the second one-conductivity-type semiconductor layer 34 is such that the first one-conductivity-type semiconductor layer 32, the first other-conductivity-type semiconductor layer 33, the second one-conductivity-type semiconductor layer 34, and the second other-conductivity-type semiconductor layer 34. It is desirable that it is the smallest of all the layers of the semiconductor layer 35 and is about 1 × 10 ¹⁶ cm ⁻³ to 1 × 10 ¹⁷ cm ⁻³ . The second one-conductivity-type semiconductor layer 34 can be made of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs), whereby high internal quantum efficiency can be obtained.

The second other conductivity type semiconductor layer 35 is formed of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs). The semiconductor material forming the second other conductive semiconductor layer 35 is the same as the energy gap of the semiconductor material forming the first other conductive semiconductor layer 33 and the second one conductive semiconductor layer 34, or the first Those having a larger energy gap than the energy gap of the semiconductor material forming the other one-conductivity-type semiconductor layer 33 and the second one-conductivity-type semiconductor layer 34 are selected. The carrier density of the second other conductivity type semiconductor layer 35 is desirably about 1 × 10 ¹⁸ cm ⁻³ .

The ohmic contact layer 37 is a semiconductor layer of the other conductivity type formed of a semiconductor material such as gallium arsenide (GaAs) or indium gallium phosphide (InGaP), and is used for performing an ohmic junction with the light emitting signal transmission path 12. is there. The carrier density of the ohmic contact layer 37 is desirably 1 × 10 ¹⁹ cm ⁻³ or more.

  A laminate in which the first one-conductivity-type semiconductor layer 32, the first other-conductivity-type semiconductor layer 33, the second one-conductivity-type semiconductor layer 34, the second other-conductivity-type semiconductor layer 35, and the ohmic contact layer 37 are laminated. Has a substantially rectangular parallelepiped shape. The first one-conductivity-type semiconductor layer 32, the first other-conductivity-type semiconductor layer 33, the second one-conductivity-type semiconductor layer 34, the second other-conductivity-type semiconductor layer 35, and the ohmic contact layer 37 are formed by the insulating layer 17. Covered. The insulating layer 17 is formed of a resin material having electrical insulation, translucency, and flatness. The insulating layer 17 is formed of polyimide, benzocyclobutene (BCB), or the like.

  A portion of the insulating layer 17 between the adjacent light emitting elements L is formed with a groove 38 that is V-shaped in a virtual plane perpendicular to the width direction Y and reaches the one surface 31 a of the substrate 31. The light-emitting element light-shielding portion 23 is formed at 38. The light-emitting element light-shielding part 23 is formed along the surface of the groove part 38 and is provided from one surface 31 a of the substrate 31 to the side in the arrangement direction X of the ohmic contact layer 37. The light emitting element light-shielding portion 23 is formed between one end and the other end in the width direction Y of the light emitting element L, and the width direction one Y1 and the other width direction of the light emitting element L than the end of the light emitting element L in the width direction Y. Extends to Y2. By forming such a light emitting element light-shielding portion 23, it is possible to prevent the adjacent light emitting element L from receiving this light, and even if the adjacent light emitting element L emits light, the light emission is accompanied by this light emission. Since the threshold voltage or threshold current of the light emitting element L does not change, the light emitting element L can selectively and stably emit light.

  The element connection portion 22 of the light emission signal transmission path 12 is connected to one surface 37 a of the ohmic contact layer 37 in the thickness direction Z. A through hole 39 is formed in a portion of the insulating layer 17 formed on the one surface 37 a of the ohmic contact layer 37 in the thickness direction Z, and a part of the element connection portion 22 is formed in the through hole 39. Thus, the element connection portion 22 is in contact with the ohmic contact layer 37. The through hole 39 is formed so that the center in the arrangement direction X of the light emitting elements L and the center in the width direction Y of the light emitting elements L are exposed from the insulating layer 17. The light can be efficiently supplied to the central portion of the light emitting element L to emit light. In the light emitting element L, light is generated mainly in the vicinity of the second one-conductivity-type semiconductor layer 34 near the interface between the second one-conductivity-type semiconductor layer 34 and the second other-conductivity-type semiconductor layer 35. To do.

  The length W6 in the arrangement direction X of the element connecting portions 22 of the light emission signal transmission path 12 is formed to be 1/3 or less of the length W2 in the arrangement direction X of the light emitting elements L. The element connection portion 22 covers a part of the light emission direction of the light emitting element L, but by selecting the length W6 as described above, the light emitted from the light emitting element L and blocking the light toward the thickness direction one side Z1 is blocked. As much as possible. Further, a part of the light emitted from the light emitting element L and directed to one side Z1 in the thickness direction and reflected by the light emitting signal transmission path 12 is reflected by the light emitting element light-shielding portion 23, the substrate 31, and the like, so that Head to the other side.

  FIG. 3 is a partial cross-sectional view showing the basic configuration of the light emitting device 10 as seen from the section line A2-A2 of FIG. The switch element T includes a first one-conductivity-type semiconductor layer 42, a first other-conductivity-type semiconductor layer 43, a second one-conductivity-type semiconductor layer 44, and a second other formed on one surface 31a of the substrate 31. A conductive semiconductor layer 45 is included.

  In the switch element T, the first one-conductivity-type semiconductor layer 42 is stacked on the one surface 31a in the thickness direction Z of the substrate 31, and the first one-conductivity-type semiconductor layer 42 is disposed on the one surface 42a in the thickness direction Z. The first other conductivity type semiconductor layer 43 is laminated, the second one conductivity type semiconductor layer 44 is laminated on one surface 43a of the thickness direction Z of the first other conductivity type semiconductor layer 43, and the second one conductivity type. The second other conductivity type semiconductor layer 45 is stacked on the one surface 44 a of the thickness direction Z of the type semiconductor layer 44, and the ohmic contact layer 47 is formed on the one surface 45 a of the thickness direction Z of the second other conductivity type semiconductor layer 45. Are stacked, and the surface electrode 25 is stacked on one surface 47 a of the ohmic contact layer 47 in the thickness direction Z. Lamination of first one-conductivity-type semiconductor layer 42, first other-conductivity-type semiconductor layer 43, second one-conductivity-type semiconductor layer 44, second other-conductivity-type semiconductor layer 45, ohmic contact layer 47, and surface electrode 25 The body has a substantially rectangular parallelepiped shape.

  Each semiconductor layer of the switch element T, that is, the one conductive type semiconductor layer 42, the first other conductive type semiconductor layer 43, the second one conductive type semiconductor layer 44, the second other conductive type semiconductor layer 45, and the ohmic contact layer 47. It is preferable that the energy gap and the carrier density of the semiconductor material constituting the semiconductor material are designed so as to increase the light receiving sensitivity of the switch element T, the light extraction efficiency to the outside, and the light emission efficiency.

The first one-conductivity-type semiconductor layer 42 is formed of a semiconductor material such as gallium arsenide (GaAs), aluminum gallium arsenide (AlGaAs), or indium gallium phosphide (InGaP). The carrier density of the first one-conductivity-type semiconductor layer 42 is preferably about 1 × 10 ¹⁸ cm ⁻³ .

The first other conductivity type semiconductor layer 43 is formed of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs). The semiconductor material forming the first other conductivity type semiconductor layer 43 is formed with the same one as the energy gap of the semiconductor material forming the first one conductivity type semiconductor layer 42 or the first one conductivity type semiconductor layer 42. A material having an energy gap smaller than that of the semiconductor material is selected. The carrier density of the first other conductivity type semiconductor layer 43 is desirably about 1 × 10 ¹⁷ cm ⁻³ .

The second one-conductivity-type semiconductor layer 44 is formed of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs). The semiconductor material forming the second one-conductivity-type semiconductor layer 44 has the same energy gap as the semiconductor material forming the first other-conductivity-type semiconductor layer 43, or the first other-conductivity-type semiconductor layer 43 is formed. A material having an energy gap smaller than that of the semiconductor material is selected. The carrier density of the second one conductivity type semiconductor layer 44 is such that the first one conductivity type semiconductor layer 42, the first other conductivity type semiconductor layer 43, the second one conductivity type semiconductor layer 44, and the second other conductivity type. It is desirable that it is the smallest of all the layers of the semiconductor layer 45 and is about 1 × 10 ¹⁶ cm ⁻³ to 1 × 10 ¹⁷ cm ⁻³ . The second one-conductivity-type semiconductor layer 44 can be made of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs), whereby high internal quantum efficiency can be obtained.

The second other conductivity type semiconductor layer 45 is formed of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs). The semiconductor material forming the second other-conductivity-type semiconductor layer 45 is the same as the energy gap of the semiconductor material forming the first other-conductivity-type semiconductor layer 43 and the second one-conductivity-type semiconductor layer 44, or the first Those having a larger energy gap than the energy gap of the semiconductor material forming the other one conductive semiconductor layer 43 and the second one conductive semiconductor layer 44 are selected. The carrier density of the second other conductivity type semiconductor layer 45 is desirably about 1 × 10 ¹⁸ cm ⁻³ .

The ohmic contact layer 47 is a semiconductor layer of the other conductivity type formed of a semiconductor material such as gallium arsenide (GaAs) or indium gallium phosphide (InGaP), and is used for ohmic contact with the surface electrode 25. The carrier density of the ohmic contact layer 47 is desirably 1 × 10 ¹⁹ cm ⁻³ or more.

  The first one-conductivity-type semiconductor layer 42 of the switch element T and the first one-conductivity-type semiconductor layer 32 of the light emitting element L are formed of the same semiconductor material and have the same thickness. The first other conductivity type semiconductor layer 43 of the switch element T and the first other conductivity type semiconductor layer 33 of the light emitting element L are formed of the same semiconductor material and have the same thickness. The second one-conductivity-type semiconductor layer 44 of the switch element T and the second one-conductivity-type semiconductor layer 34 of the light-emitting element L are formed of the same semiconductor material and have the same thickness. The second other conductivity type semiconductor layer 45 of the switch element T and the second other conductivity type semiconductor layer 35 of the light emitting element L are formed of the same semiconductor material and have the same thickness. The ohmic contact layer 47 of the switch element T and the ohmic contact layer 37 of the light emitting element L are formed of the same semiconductor material and have the same thickness.

  In the switch element T, the second one-conductivity-type semiconductor layer 44 and the second other-conductivity-type semiconductor layer 45 form a light emitting part that mainly generates light, and the first one-conductivity-type semiconductor layer 42 and the first other-conductivity-type semiconductor layer 45 are formed. A light receiving portion mainly receiving light, that is, a phototransistor portion is formed by the conductive semiconductor layer 43 and the second one conductive semiconductor layer 44.

  The thickness of the first other conductivity type semiconductor layer 43 of the switch element T is selected from 50 to 1000 mm. Thus, by selecting the thickness of the first other conductivity type semiconductor layer 43, the first one conductivity type semiconductor layer 42, the first other conductivity type semiconductor layer 43, and the second one conductivity type semiconductor layer 44 are used. The current amplification factor of the formed phototransistor portion is increased and light from the outside can be efficiently received.

  On the one surface 47a of the thickness direction Z of the ohmic contact layer 47, the surface electrode 25 is provided in ohmic contact. The surface electrode 25 is located in a region approximately half the area of the one surface 47a near the downstream side in the scanning direction, in other words, near the other X2 in the arrangement direction, except for the peripheral portion of the one surface 47a in the thickness direction Z of the ohmic contact layer 47. It is formed. By forming the surface electrode 25 in this manner, the electric field applied to each semiconductor layer of the switch element T can be made as uniform as possible, and the emission intensity of light emitted from the switch element T can be increased. At the same time, more light that is emitted from the switch element T adjacent to the one side X1 in the arrangement direction, reflected by the light-shielding layer 18, and arrives from one side Z1 in the thickness direction can be incident on each semiconductor layer. Therefore, in the other arrangement direction X2 which is the downstream side of the scanning direction of the switch element T, the light is reflected by the surface electrode 25, whereby stronger light can be given to the switch element T in the other arrangement direction X2. Since the surface electrode 25 is not formed in the arrangement direction one X1, which is the upstream side in the scanning direction, light that is reflected by the scanning signal transmission path 15 or the light shielding layer 18 and that arrives from the thickness direction one Z1 is efficiently received. can do. The surface electrode 25 is formed of a conductive material such as a metal material and an alloy material. Specifically, the surface electrode 25 is formed of gold (Au), an alloy of gold and germanium (AuGe), an alloy of gold and zinc (AuZn), or the like.

  The first one-conductivity-type semiconductor layer 42, the first other-conductivity-type semiconductor layer 43, the second one-conductivity-type semiconductor layer 44, the second other-conductivity-type semiconductor layer 45, the ohmic contact layer 47, and the surface electrode 25 are It is covered with the insulating layer 17 and is electrically insulated from the adjacent switch element T. As described above, since the insulating layer 17 has translucency, when the switch element T emits light, the light passes through the insulating layer 17 and enters the switch element T adjacent in the arrangement direction X. The insulating layer 17 is formed of a resin material that transmits 95% or more of light having a wavelength emitted from the switch element T.

  As indicated by the arrows in FIG. 3, the switch element T is located near the interface between the second one-conductivity-type semiconductor layer 44 and the second other-conductivity-type semiconductor layer 45 and close to the second one-conductivity-type semiconductor layer 44. Mainly emits light from the area. Further, light is emitted slightly in the vicinity of the interface between the first one-conductivity-type semiconductor layer 42 and the first other-conductivity-type semiconductor layer 43. The switch element T emits light in all directions.

  By forming the insulating layer 17 from a resin material having flatness, when the insulating layer 17 is formed, the resin material is also filled between the switch elements T so that the insulating layer 17 is interposed between the switch elements T. Can be reliably formed. The insulating layer 17 is formed by applying a resin material and curing the resin material. When the resin material shrinks during curing, a recess 48 extending in the width direction Y is formed on the surface portion of the thickness direction one Z1 of the insulating layer 17 formed between the switch elements T.

  By forming the insulating layer 17 from polyimide, benzocyclobutene (BCB), etc., the insulating layer 17 can be reliably formed in this gap even if the interval W3 between the switch elements T is selected as described above. The first one-conductivity-type semiconductor layer 42, the first other-conductivity-type semiconductor layer 43, the second one-conductivity-type semiconductor layer 44, the second other-conductivity-type semiconductor layer 45, the ohmic contact layer 47, the surface electrode 25, and The insulating layer 17 can be formed in close contact with the substrate 31. If the insulating layer 17 is peeled off from the surface of the switch element T, light is reflected by the interface of the peeled portion, and the amount of light received from the adjacent switch element T may be reduced. There is no such problem.

  Any one of the first to third scanning signal transmission lines 15a, 15b, 15c is connected to one surface 25a of the thickness direction Z of the surface electrode 25. A through hole 49 is formed in a portion of the insulating layer 17 formed on one surface 25 a of the thickness direction Z of the surface electrode 25, and the first to third scanning signal transmission paths 15 a are formed through the through hole 49. , 15b, 15c are connected to each other, and the switching element T and the other two scanning signal transmission paths 15 of the first to third scanning signal transmission paths 15a, 15b, 15c are insulated layers. 17 is electrically insulated. Since the switch element T is covered with the insulating layer 17, the first to third scanning signal transmission lines 15a, 15b, and 15c can be stacked on one side Z1 in the thickness direction of the switch element T.

  In the present embodiment, one conductivity type is N-type, and the other conductivity type is P-type. In the light emitting element L and the switch element T, when one conductivity type is N type and the other conductivity type is P type, the light emission signal transmission path 12 and the scanning signal transmission path 15 are connected to the anode of each element. A cathode potential of 0 volts (V) is preferable because a positive power source can be used as a power source for applying voltage or current to the light emitting element L and the switch element T. In the present embodiment, in the light emitting element L, the light emission signal transmission path 12 functions as an anode terminal, and the back electrode 36 functions as a cathode terminal. In the switch element T, the front electrode 25 functions as an anode terminal together with the scanning signal transmission path 15, and the back electrode 36 functions as a cathode terminal.

  On one side in the thickness direction Z of each switch element T, the insulating layer 17 and the scanning signal transmission line 15 are covered with a light shielding layer 18. Various materials can be used as the material of the light shielding layer 18 as long as they are electrically insulating and absorb light of a wavelength emitted from the switch element T almost completely with a thickness of about 2 μm to 3 μm. is there. In the present embodiment, the light shielding layer 18 is formed of green polyimide. The thickness of the light shielding layer 18 is selected to be about 5 μm to 10 μm.

  Is the light emitted from the switch element T and directed toward one side Z1 in the thickness direction reflected by the interface between the insulating layer 17 and the scanning signal transmission path 15, the scanning signal transmission path 15, the interface between the insulating layer 17 and the light shielding layer 18, or the like? And is absorbed by the light shielding layer 18. Each scanning signal transmission line 15 and the insulating layer 17 form a reflecting means. This prevents the light from the switch element T from interfering with the light emitted from the light emitting element L in the thickness direction one Z1. Therefore, when the light emitting device 10 is used as an exposure device of an image forming apparatus 87 described later, an image of excellent quality can be formed without causing image degradation due to leakage light from the switch element T.

  FIG. 4 is a partial cross-sectional view showing the basic configuration of the light emitting device 10 as seen from the section line A3-A3 in FIG. The light emitting element L and the switch element T are arranged adjacent to each other in the width direction Y. The ends of the first one-conductivity-type semiconductor layer 32, the first other-conductivity-type semiconductor layer 33, and the second one-conductivity-type semiconductor layer 34 of the light-emitting element L near the switch element T The light emitting element connection portion 51 is configured to protrude toward the switch element T from the end of the conductive semiconductor layer 35 and the ohmic contact layer 37 near the switch element T. The length of the light emitting element connection portion 51 in the arrangement direction X is slightly smaller than the length W2 described above.

  The end of the switch element T near the light emitting element L of the first one-conductivity-type semiconductor layer 42, the first other-conductivity-type semiconductor layer 43, and the second one-conductivity-type semiconductor layer 44 is The other conductive type semiconductor layer 45 and the ohmic contact layer 47 protrude toward the switch element T from the end portion near the light emitting element L, thereby forming the switch element connection portion 52. The length of the switch element connection portion 52 in the arrangement direction X is selected to be equal to the length of the light emitting element connection portion 51 in the arrangement direction.

  Of the second one-conductivity-type semiconductor layer 34 of the light-emitting element L, the portion 34A constituting the light-emitting element connection portion 51 is formed to be smaller in thickness than the portion 34B where the second other-conductivity-type semiconductor layer 35 is laminated. The Of the second one-conductivity-type semiconductor layer 44 of the light-emitting element switch T, the portion 44A constituting the switch-element connection portion 52 has a smaller thickness than the portion 44B where the second other-conductivity-type semiconductor layer 45 is laminated. It is formed.

  The insulating layer 17 is formed along the surfaces of the light emitting element L and the switch element T, and is also formed between the light emitting element L and the switch element T. The light emitting element L and the switch element T are electrically connected by the insulating layer 17. Insulated. The thickness of the insulating layer 17 provided between the light emitting element L and the switch element T is substantially equal to the thickness of the light emitting element connection portion 51 and the switch element connection portion 52 from the substrate 31. In the insulating layer 17, a portion provided between the light emitting element L and the switch element T is formed with a recess 53 extending along the arrangement direction X, with the substrate 31 side being the bottom. In the insulating layer 17, a through hole 54 is formed in a portion of the light emitting element connection portion 51 that is stacked on the one surface 34 a of the second one-conductivity-type semiconductor layer 34 in the thickness direction Z, and the switch element connection portion Through holes 55 are respectively formed in portions of the second one-conductivity-type semiconductor layer 52 that are stacked on the one surface 44a of the thickness direction Z.

  The connection means 14 for connecting the gate 19 of the light emitting element L and the gate 24 of the switch element T corresponding to the light emitting element L extends over the light emitting element connecting portion 51 and the switch element connecting portion 52. The insulating layer 17 is stacked between the T and the insulating layer 17. The connection means 14 includes a part of the connection means 14 formed in the through holes 44 and 45, the one surface 34 a in the thickness direction Z of the second one-conductivity-type semiconductor layer 34 of the light emitting element connection portion 51, and the switch element The connection portion 52 is connected to the one surface 44a of the thickness direction Z of the second one-conductivity-type semiconductor layer 44. The resistance value of the connecting means 14 is selected to be 1 kΩ (ohms) or less. If the resistance value is too high, the trigger signal from the switch element T to the light emitting element L is attenuated, but the trigger signal from the switch element T to the light emitting element L is selected by selecting the resistance value of the connecting means 14 within the above range. Is transmitted without attenuation.

  The second one-conductivity-type semiconductor layer 34 of the light-emitting element L is the gate 19 of the light-emitting element L, and the second one-conductivity-type semiconductor layer 44 of the switch element T is the gate 24 of the switch element T. Therefore, the connection means 14 electrically connects the gates of the light emitting element L and the switch element T.

  The ends of the second other-conductivity-type semiconductor layer 35 and the ohmic contact layer 37 of the light-emitting element L near the switch element T are covered with the above-described light-emitting signal transmission path 12 via the insulating layer 17. As a result, light traveling from the light emitting element L toward the switch element T can be shielded. The signal path extending portion 21 of the light emitting signal transmission path 12 is provided facing the side of the second other conductive type semiconductor layer 35 and the ohmic contact layer 37 facing the switch element T, and the light emitting element connecting portion 51 The end near the second other conductivity type semiconductor layer 35 is covered.

  The ends of the switch element T near the light emitting element L of the second other conductive type semiconductor layer 45 and the ohmic contact layer 47 are covered with the light shielding layer 18 laminated on the insulating layer 17. Thereby, the light traveling from the switch element T toward the light emitting element L can be shielded. Further, the end of the switch element T opposite to the light emitting element L is covered with the light shielding layer 18 via the insulating layer 17. The light shielding layer 18 covers one side in the thickness direction Z of the switch element connecting portion 52 and extends to the vicinity of the recess 53 formed between the light emitting element L and the switch element T.

  FIG. 5 is a partial cross-sectional view showing a basic configuration of the light-emitting device 10 as viewed from the section line A4-A4 of FIG. Since the scanning start switch element T0 and the switch element T have the same configuration, the same parts are denoted by the same reference numerals, and redundant description may be omitted.

  In the scanning start switch element T0, the first one-conductivity-type semiconductor layer 62 is laminated on the one surface 31a of the thickness direction Z of the substrate 31, and the one surface of the first one-conductivity-type semiconductor layer 62 in the thickness direction Z. A first other conductivity type semiconductor layer 63 is laminated on 62a, a second one conductivity type semiconductor layer 64 is laminated on one surface 63a of the thickness direction Z of the first other conductivity type semiconductor layer 63, and a second The second other conductivity type semiconductor layer 65 is laminated on one surface 64a of the thickness direction Z of the one conductivity type semiconductor layer 64, and ohmic on the one surface 65a of the second other conductivity type semiconductor layer 65. The contact layer 67 is laminated, and the surface electrode 25 is formed on the one surface 67 a in the thickness direction Z of the ohmic contact layer 67. The surface electrode 25 of the scanning start switch element T0 is formed in the entire region except the peripheral portion of the one surface 61a of the ohmic contact layer 61. The first one-conductivity-type semiconductor layer 62, the first other-conductivity-type semiconductor layer 63, the second one-conductivity-type semiconductor layer 64, the second other-conductivity-type semiconductor layer 65, the ohmic contact layer 67, and the surface electrode 25 are stacked. The body has a substantially rectangular parallelepiped shape.

  The first one-conductivity-type semiconductor layer 62 of the scanning start switch element T0 and the first one-conductivity-type semiconductor layer 42 of the switch element T are formed of the same semiconductor material and have the same thickness. The first other conductive semiconductor layer 63 of the scanning start switch element T0 and the first other conductive semiconductor layer 43 of the switch element T are formed of the same semiconductor material and have the same thickness. The second one-conductivity-type semiconductor layer 64 of the scanning start switch element T0 and the second one-conductivity-type semiconductor layer 44 of the switch element T are formed of the same semiconductor material and have the same thickness. The second other conductivity type semiconductor layer 65 of the scanning start switch element T0 and the second other conductivity type semiconductor layer 45 of the switch element T are formed of the same semiconductor material and have the same thickness. The ohmic contact layer 67 of the scanning start switch element T0 and the ohmic contact layer 47 of the switch element T are formed of the same semiconductor material and have the same thickness.

  Further, end portions of the scanning start switch element T0 near the light emitting element L of the first one-conductivity-type semiconductor layer 62, the first other-conductivity-type semiconductor layer 63, and the second one-conductivity-type semiconductor layer 64 are The second other conductive type semiconductor layer 65 and the ohmic contact layer 67 protrude toward the light emitting element array 11 side from the end portion near the light emitting element L, and constitute a scanning start switch element connecting portion 68.

  The scanning start switch element T0 is covered with the insulating layer 17 and the light shielding layer 18. The scanning signal transmission path 15 is formed by laminating on the insulating layer 17 laminated on one side in the thickness direction of the scanning start switch element T0, and the portion of the insulating layer 17 laminated on one side in the thickness direction of the scanning start switch element T0. A part of the third scanning signal transmission path 15c is formed in the through-hole 69 formed in the first through-hole 69, and the third scanning signal transmission path 15c is connected to the surface electrode 25 of the scanning start switch element T0 through the through-hole 69. The Further, in the insulating layer 17, a through hole 71 is formed in a portion where the scanning start switch element connection portion 68 is laminated, and a part of the start signal transmission path 16 is formed in the through hole 71. The start signal transmission line 16 formed by being laminated on the insulating layer 17 is connected via the. The scanning start switch element T 0, the scanning signal transmission path 15, and the start signal transmission path 16 are covered with a light shielding layer 18.

  The second one-conductivity-type semiconductor layer 64 of the scan start switch element T0 is the gate 26 of the scan start switch element T0.

  Each light emitting element L, each switch element T, and scanning start switch element T0 are formed on one surface 31a of the substrate 31 with a first one-conductivity-type semiconductor layer 32, 42, 62, a first other-conductivity-type semiconductor layer 33, 43, 63, second one-conductivity-type semiconductor layers 34, 44, 64, second other-conductivity-type semiconductor layers 35, 45, 65, and ohmic contact layers 37, 47, 67, respectively. The layers are sequentially stacked by epitaxial growth and chemical vapor deposition (CVD), and then patterned and etched by photolithography. Therefore, since the light emitting element L, the switch element T, and the scan start switch element T0 can be formed simultaneously in a series of manufacturing processes, the manufacturing cost can be reduced. After forming each semiconductor layer, a conductor layer is formed by a vapor deposition method or the like, and patterned and etched by photolithography to form the surface electrode 25.

  After the surface electrode 25 is formed, the insulating layer 17 is spin-coated with the above-described resin material such as polyimide, and then the applied resin material is cured, so that the light emission signal transmission path 12, the connection means 14, Each through-hole 39, 49, 54, 55 required for connection of the third scanning signal transmission path 15a, 15b, 15c, the start signal transmission path 16, and the light emitting element L, the switching element T or the scanning start switching element T0. 69, 71 are formed by patterning and etching by photolithography.

  The light emitting signal transmission path 12, the connecting means 14, the first to third scanning signal transmission paths 15a, 15b, 15c, the start signal transmission path 16, and the light emitting element light shielding portion 23 are formed after the insulating layer 17 is formed. The light emitting signal transmission path 12, the connection means 14, the first to third scanning signal transmission paths 15a, 15b, 15c, the start signal transmission path 16, and the conductive material on the surface of the insulating layer 17 by vapor deposition or the like. After the stacking, they are simultaneously formed by patterning and etching by photolithography. Therefore, the light emitting signal transmission path 12, the connection means 14, the first to third scanning signal transmission paths 15a, 15b, 15c, the start signal transmission path 16, and the light emitting element light shielding portion 23 are formed to be substantially equal in thickness. The

  FIG. 6 is a graph showing forward voltage-current characteristics, which are relationships between the anode voltage and the anode current, of the light emitting element L, the switch element T, and the scan start switch element T0. In FIG. 6, the horizontal axis indicates the anode voltage, and the vertical axis indicates the anode current. In FIG. 6, a load line 72 is also shown. The light emitting element L, the switch element T, and the scan start switch element T0 are in the off state where the characteristic curve representing the voltage-current characteristic and the load line 72 intersect, and the on state where the characteristic curve and the load line 72 intersect. Transition to point a. The anode voltage represents the anode potential when the cathode potential is 0 (zero) volts (V), and the anode current represents the current flowing through the anode.

The initial threshold voltage (breakover voltage) of the light emitting element L, the switch element T, and the scan start switch element T0 is defined as V _BO . The initial threshold voltage is a threshold voltage when the trigger signal is not applied to the gate 19 in the light emitting element L, and is a threshold voltage when no light is received by the switch element T. In the switch element T0, the threshold voltage is in a state where no trigger signal is applied to the gate 26.

In the light-emitting element L and the scan start switch element T0, by providing a trigger signal to the gate 19 and 26, the threshold voltage _{V BO,} as indicated by the arrow P1 in FIG. 6, voltage smaller than the _{V BO} When the threshold voltage drops to V _TH , and the switch element T receives light, the threshold voltage is reduced from V _BO to a voltage smaller than this V _BO as indicated by an arrow P1 in FIG. It drops to a certain _VTH .

  FIG. 7 is a circuit diagram showing a part of an equivalent circuit showing the basic configuration of the light emitting device 10 shown in FIG. The light emitting device 10 further includes driving means 73. The driving means 73 is connected to the first to third scanning signal transmission paths 15a, 15b, 15c, the light emission signal transmission path 12, and the start signal transmission path 16, and the first to third scanning signal transmission paths 15a, 15b. , 15c, a start signal φS is applied to the start signal transmission path 16, and a light emission signal φE is applied to the light emission signal transmission path 12. The driving means 73 is realized by a driving driver IC (Integrated Circuit).

  The driving means 73 receives a clock pulse signal as a reference from the outside, and outputs the first to third scanning signals φ1 to φ3 and the start signal φS in synchronization with the clock pulse signal to transmit the scanning signal. Are provided to the path 15 and the start signal transmission path 16, respectively. The clock pulse signal is supplied from the control unit 96 of the image forming apparatus 87 described later. The clock cycle of the clock pulse signal is selected to be longer than the control cycle in the control means 96 of the image forming apparatus 87 described later. Further, the driving means 73 outputs the light emission signal φE based on the image information given together with the clock pulse signal and gives it to the light emission signal transmission path 12.

  The first to third scanning signal transmission lines 15a, 15b, and 15c are connected to resistance elements Rφ connected in series with the switch elements T, respectively, and the driving means 73 is connected to the first to the third scanning signal transmission lines 15a, 15b, and 15c via the resistance elements Rφ. The three scanning signal transmission paths 15a, 15b, and 15c are connected. The resistance element Rφ has a function as a voltage dividing resistor that divides the voltage applied to each switch element T while preventing an overcurrent from flowing from the driving means 73 to the scanning signal transmission line 15.

  Also, the light emitting signal transmission path 12 is connected with a resistance element Rφ connected in series with each light emitting element L, and the driving means 73 is connected to the light emission signal transmission path 12 via the resistance element Rφ. The resistance element Rφ has a function as a voltage dividing resistor that divides the voltage applied to each light emitting element L while preventing an overcurrent from flowing from the driving means 73 to the light emitting signal transmission path 12.

  FIG. 8 shows the start signal φS given to the start signal transmission path 16 by the driving means 73, the first scanning signal φ1 given to the first scanning signal transmission path 15a, the second scanning signal φ2 given to the second scanning signal transmission path 15b, The third scanning signal φ3 applied to the third scanning signal transmission path 15c and the light emission signal φE applied to the light emission signal transmission path 12, the light emission intensity of the light emitting element L1, and the light emission intensity of the scanning start switch element T0 and the switch elements T1 to T4. FIG. The light emission intensity of the light emitting element L1, the scanning start switch element T0, and the switch elements T1 to T4 indicates that light is emitted when the level is high (H), and indicates that no light is emitted when the level is low (L). . In FIG. 8, the horizontal axis represents time, and represents the elapsed time from the reference time.

  For the start signal φS, the first to third scanning signals φ1 to φ3, and the light emission signal φE, the vertical axis represents the signal level. The signal level represents the magnitude of voltage or current. When the start signal φS, the first to third scanning signals φ1 to φ3, and the light emission signal φE are at a high (H) level, a high voltage or high current is applied to the signal transmission line. When the start signal φS, the first to third scanning signals φ1 to φ3, and the light emission signal φE are at the low (L) level, a low voltage or a low current is supplied to the signal transmission line. When the start signal φS, the first to third scanning signals φ1 to φ3, and the light emission signal φE are at the L level, the voltage or current supplied to the transmission line is smaller than the threshold voltage or threshold current of each element. In the case of voltage, the high level is, for example, 3 volts (V) to 10 volts (V). In the case of voltage, the low level is, for example, 0 (zero) volts (V).

  In the present embodiment, the voltage of the start signal φS, the first to third scanning signals φ1 to φ3, and the light emission signal φE at the H level is, for example, 5 volts (V), and the L level start signal φS, The voltages of the third scanning signals φ1 to φ3 and the light emission signal φE are set to 0 volts (V), for example. The waveforms of the first to third scanning signals φ1 to φ3 are the same and have different phases.

  In the light emitting device 10, the light emitting state of the switch element T is transferred along the arrangement direction X in order to reduce the threshold voltage or the threshold current of the light emitting element L to emit light.

  Hereinafter, the operation of the driving unit 73 will be described. First, at time t0, the driving unit 73 sets the start signal φS, the first to third scanning signals φ1 to φ3, and the light emission signal φE to a low level. By setting the start signal φS to the low level, the threshold voltage or the threshold current of the scanning start switch element T0 becomes smaller than the high level of the third scanning signal φ. When the signal level is changed from the low level to the high level for the light emission signal φE, the start signal φS, and the scanning signal φ, the driving unit 73 changes the signal level to the high level until the signal level is changed from the high level to the low level next time. To maintain. Further, when the signal level is changed from the high level to the low level for the light emission signal φE, the start signal φS, and the scanning signal φ, the driving unit 73 sets the signal level to the low level until the signal level is changed from the low level to the high level next time. To keep.

  At time t1, the driving unit 73 changes only the third scanning signal φ3 from the low level to the high level. At time t1, the start signal φS, the first and second scanning signals φ1, φ2, and the light emission signal φE are at a low level. As a result, the scanning start switch element T0 is turned on, that is, turned on and emits light.

  The light of the scanning start switch element T0 is most strongly incident on the switch element T1 arranged at the end portion in the arrangement direction X of the adjacent switch element array 13. In the other switch elements T of the switch element array 13, the intensity of light emitted from the scan start switch element T0 is smaller as the switch element T is arranged at a position away from the scan start switch element T0 in the arrangement direction X. Become. In the switch element T, when light is received, carriers corresponding to the received light intensity are generated in each semiconductor layer by photoexcitation. Electrons accumulated in the second one-conductivity-type semiconductor layer 44 due to the generation of carriers lowers the Fermi level of the second one-conductivity-type semiconductor layer 44, and thereby the first other-conductivity-type semiconductor layer 43 and the second one-conductivity-type semiconductor layer 43. The avalanche phenomenon is likely to occur at the junction with the two one-conductivity type semiconductor layer 44. For this reason, the switching element T has a characteristic that the threshold voltage or threshold current decreases by receiving light, and the threshold voltage or threshold current drops more as the received light intensity increases. .

  Next, the transfer of the light emission state from the scanning start switch element T0 to the switch element T1 will be described. When the scanning start switch element T0 emits light, the switch element T1 receives this light, and the threshold voltage of the switch element T1 decreases.

At time t2, the threshold voltage of the switch element T1 is V _TH (T1). Switch elements T1, T4,..., Tj-2 are connected to the first scanning signal transmission line 15a, but the switch elements T4,..., Tj-2 are sufficiently separated from the scanning start switch element T0. Therefore, even if light from the scanning start switch element T0 is received, the light is weak, so that the threshold voltage hardly changes.

  At time t2, the driving unit 73 changes the first scanning signal φ1 from the low level to the high level. At time t2, the start signal φS, the second scanning signal φ2, and the light emission signal φE are at a low level, and the third scanning signal φ3 is at a high level. The high level of the first scanning signal φ1 is lower than the threshold voltage or threshold current of the other switching elements T4,..., Tj-2 except the switching element T1 connected to the first scanning signal transmission line 15a. Is also selected for high voltage or high current.

  The scanning signal transmission path 15 to which the switching element T whose threshold voltage or threshold current has been lowered by receiving light from the adjacent switching element T is connected to the scanning signal transmission path 15 is connected to the scanning signal transmission path 15. When a scanning signal φ having a voltage or current higher than the minimum threshold voltage or threshold current of the switch element T is applied, the scanning signal φ is applied to the scanning signal transmission line 15 via the resistance element Rφ, and the switching element A voltage divided by the resistance element Rφ is applied to T. A voltage divided by the resistance element Rφ is gradually applied to each switch element T, and among the plurality of switch elements T connected to the same scanning signal transmission path 15, the adjacent switch element T The voltage or current applied to the switch element T that has received the light from the first becomes the threshold voltage or threshold current of the switch element T earliest. Thereby, only the switch element T with the lowest threshold voltage or threshold current emits light, and the other switch elements T do not emit light.

  Accordingly, at time t2, the switch element T1 is turned on, that is, turned on and emits light.

  After the switch element T1 is turned on, the driving unit 73 sets the third scanning signal φ3 to the low level at time t3. Accordingly, the scanning start switch element T0 is turned off, that is, turned off and turned off.

  In this way, the light emission state transitions from the scanning start switch element T0 to the switch element T1. Further, at time t3, the driving means 73 changes the start signal φS from the low level to the high level, and thereafter maintains the high level, thereby changing the third scanning signal φ3 from the low level to the high level after time t3. The scanning start switch element T0 maintains the off state.

  The time between the time t2 and the time t3 is selected to be about 1/10 of the time when the first scanning signal φ1 becomes high level. In this way, the drive means 73 provides the scanning signal φ so that the time when the scanning signal φ applied to the adjacent switch element T is at the high level overlaps, whereby the threshold voltage or threshold current of the adjacent switch element T is applied. Is reliably lowered, the scanning signal φ can be set to a high level, and optical scanning can be performed reliably.

  In the present embodiment, the time during which the first to third scanning signals φ1 to φ3 are at a high level is selected to be about 1 μsecond (μsecond). Accordingly, the time between time t2 and time t3 is selected to be about 0.1 μsecond (μsecond).

  The switch element T1 generates a trigger signal at the gate 24 by light reception. When the switch element T1 is turned on at time t2, the switch element T1 maintains the on state until the high-level scanning signal φ becomes the low level. In the on state, the voltage of the gate 24 of the switch element T1 becomes approximately 0 (zero) volts (V). Here, the voltage of the gate 24 of the switch element T1 is a potential difference between the gate 24 and the back electrode 36 that is grounded. Since the gate 24 of the switch element T1 is connected to the gate 19 of the light emitting element L1, the voltage of the gate 24 of the switch element T1 becomes equal to the voltage of the gate 19 of the light emitting element L1. Thus, the switch element T1 can change the voltage applied to the gate 19 and the back electrode 36 of the light emitting element L1.

  When the light emitting element L1 emits light, the driving unit 73 changes the light emission signal φE from the low level to the high level at time t4 after the time t3 when the third scanning signal φ3 is changed from the high level to the low level has elapsed.

In the light emitting element L1, since the switch element T1 is in the ON state, as described above, the gate 19 of the light emitting element L1 is approximately 0 (zero) volts (V). At this time, the switch elements T2,..., Tj-1, Tj are in the off state, and the threshold voltage of the light emitting element L1 at time t4 is V _TH (L1), and the light emitting elements L2,. , Li threshold voltages V _TH (L2),..., V _TH (Li-1), V _TH (Li), respectively, the high level V _H of the light emission signal φE is equal to or higher than the threshold voltage of the light emitting element L. Then, by selecting a threshold voltage of the light emitting elements L2,..., Li-1, Li that is smaller than the lowest value, only the light emitting element L1 is selectively turned on to emit light. Can do.

  At time t5, when the driving unit 73 sets the light emission signal φE to the low level, the light emitting element L1 is turned off and turned off. The amount of exposure to a photosensitive drum 90 to be described later is adjusted according to the light emission time of the light emitting element L while the light emission intensity of the light emitting element L is constant. That is, the exposure amount is determined by determining the time between time t4 and time t5 when the light emission signal φE becomes high level. When changing the exposure amount according to the light emission intensity of the light emitting element L, it is difficult because the voltage or current applied to the light emitting element L1 needs to be finely controlled. However, by changing the exposure amount according to the light emission time, the light emission signal φE is changed. Since it is only necessary to adjust the high level time, it is easy to control the exposure amount, and a constant voltage or constant current is applied to the light emitting element L, so that the light emitting element L1 can emit light stably. The time during which the light emitting element L emits light, in other words, the time during which the light emission signal φE is at the high level, is selected to be 80% or less of the time during which the scanning signal φ is at the high level.

  After the time t5 has elapsed, when the driving unit 73 sets the second scanning signal φ2 to the high level at the time t6, the switch element T2 emits light. After the time t6 has elapsed, the driving unit 73 outputs the first scanning signal φ1 at the time t7. When the level is low, the switch element T1 is turned off. As a result, the light emission state shifts from the switch element T1 to the switch element T2.

  After the elapse of time t7, when the driving unit 73 sets the third scanning signal φ3 to the high level at time t8, the switch element T3 emits light. After the elapse of time t8, the driving unit 73 outputs the second scanning signal φ2 at time t9. When the level is low, the switch element T2 is turned off. As a result, the light emission state is shifted from the switch element T2 to the switch element T3.

  After the time t9 has elapsed, when the driving unit 73 sets the first scanning signal φ1 to the high level again at time t10, the switch element T4 emits light.

  The time between the time t6 and the time t7 is selected to be about 1/10 of the time when the second scanning signal φ2 becomes high level, and the time between the time t8 and the time t9 is determined by the third scanning signal φ3. It is selected to be about 1/10 of the time for high level.

  Thus, the driving means 73 repeatedly applies the first to third scanning signals φ1 to φ3, so that the ON state is sequentially transferred along the arrangement direction X also in the switch elements T4,..., Tj−1, Tj. Is done. When the switch element T emits light, the light emission signal φE of the light emission signal transmission path 12 is changed from low level to high level to correspond to the light emitting switch element T, that is, the light emitting switch element T. Only the light emitting element L connected to can be made to emit light selectively.

  The switch elements T positioned on both sides in the arrangement direction X of the switch elements T that are emitting light are all excited, but as described above by the first to third scanning signal transmission paths 15a, 15b, and 15c. The first to third scanning signals φ1 to φ3 are transmitted to the switching elements T and the first to third scanning signals φ1 to φ3 are given to the switching elements T, so that the switching elements T are switched from one to the other in the arrangement direction X. The light emission state can be transferred, in other words, optical scanning can be performed.

FIG. 9 is a waveform diagram showing a change in threshold voltage of the switch elements T1, T4, T7 connected to the first scanning signal transmission line 15a. In FIG. 9, the horizontal axis represents time, and represents the elapsed time from the reference time. In the figure, a start signal φS and first to third scanning signals φ1 to φ3 are also shown. Times t1, t2, t7, t8, and t10 shown in the figure correspond to the times t1, t2, t7, t8, and t10 shown in FIG. The initial threshold voltage of the switch elements T1, T4, T7 and V _BO, the threshold voltage lowered by receiving from the switch element T, or scan start switch element T0 adjacent to V _1.

Since the scan start switch element T0 emits light at time t1, the threshold voltage of the switch element T1 gradually decreases by receiving the light of the scan start switch element T0, and the threshold of the switch element T1 at time ta. voltage, becomes _{V 1.} Until time t3 at which the light emitting state of the scan start switch element T0 is maintained, threshold voltage of the switching element T1 is maintained at V _1.

At time t2, by the first scan signal φ1 changes from low level to high level, and the light-emitting switch element T1 is the threshold voltage of the switching element T1 is further at time tb decreases, the V _2. At time tb, the threshold voltage of the switch elements T4 and T7 is V _BO .

In time t7, the when the first scan signal φ1 changes from high level to low level, the threshold voltage of the switching element T1 is with time, gradually rises from V _2.

Since the switch element T3 emits light at time t8, the threshold voltage of the switch element T4 gradually decreases by receiving light from the switch element T3, and the threshold voltage of the switch element T3 becomes V ₁ at time tc. Become.

At time t10, the threshold voltage of the switch element T4 is _{V 1,} the threshold voltage of the switch element T1 is a lower _{V 3} than higher _{V BO} than _{V 1,} the threshold voltage of the switch element T7 is , V _BO .

At time t10, the first scanning signal φ1 is changed from the low level to the high level. This high level voltage is supplied from the adjacent switching element T among the switching elements T connected to the first scanning signal transmission path 15a. in one of the switch element T that is not receiving light, by higher than the threshold voltage V ₃ of the most threshold voltage lower switching element T1, it is possible to emit only the switch element T4. When the switch element T4 emits light, the threshold voltage further decreases and becomes V ₂ at time td.

In time t11, the when the first scan signal φ1 changes from high level to low level, the threshold voltage of the switching element T4 is with the passage of time, gradually rises from V _2.

FIG. 10 is a graph showing the forward voltage-current characteristics of the switch element T and the range of the high-level voltage V _H of the first to third scanning signals φ 1 to φ 3 supplied to each scanning signal transmission line 15. is there. In FIG. 10, the horizontal axis indicates the anode voltage, and the vertical axis indicates the anode current. As shown by the characteristic curve in the figure, the switch element T has an S-shaped negative resistance similar to a general thyristor. The switch element T can reduce the threshold voltage or the threshold current by irradiating the semiconductor layer constituting the switch element T with light. Thus, as described above, the switching element T functions as a switch because it transits from the point b in the off state where the characteristic curve and the load line 72 intersect to the point a in the on state where the characteristic curve and the load line 72 intersect. To do.

The initial threshold voltage of the switch element T is set to V _B0, and the threshold voltage in the state where the threshold voltage is most lowered by irradiating the switch element T with light is set to V _1, and is connected to the same scanning signal transmission line 15. The threshold voltage of the switch element T having the second lowest threshold voltage among the switch elements T is V ₃ . This V ₃ is the level of the switch element T in which the threshold voltage is slightly lowered by receiving light, or the switch element T that is being restored to the initial state at the time of turn-off, that is, once turned on. The threshold voltage.

The first to the voltage V _H of the high level of the third scan signal φ1~φ3 supplied to the scanning signal transmission path 15 connected to the switch element T is in the range indicated by reference numeral P2 in Fig. 10, ie the voltage V ₃ Is set higher. The voltage V _H is selected to be lower than the rated voltage of the switch element T. For example, when the voltage V _H is increased, the switching speed of the switch element T from the off state to the on state can be increased, and thereby the transition of the light emission state in the switch element T can be speeded up. The speed can be increased. For example, when operating with a clock signal of 1 megahertz (MHz) at 5 milliamperes (mA), the voltage V _H is selected to be about 10 V, and the resistance value of the resistance element Rφ is selected to be 1.6 kΩ. As the voltage of the scanning signal φ increases, it is necessary to limit the current flowing into the switch element T. Therefore, it is necessary to increase the resistance value of the resistance element Rφ. Therefore, the resistance value of the resistance element Rφ is determined in consideration of the time constant determined by the resistance value of the resistance element Rφ and the capacitance value of the optical switch element T when the speed of optical scanning needs to be further increased. Is done.

  In the present embodiment, since the high level voltage of the scanning signal φ is set as described above, the threshold voltage or threshold current when the switch element T receives light and is photoexcited is the initial threshold voltage. Or even if it is only about 80% of the threshold current, transfer of the light emission state can be realized by the switch element T. Therefore, even if the switch element T does not have a high light receiving sensitivity, the light emitting state can be transferred. The switch element T is formed of the same semiconductor material as that of the light emitting element L and has a similar structure. Since the light emitting element L is required to have high light emitting efficiency, if the light emitting element L is designed to increase the light emitting efficiency, the light receiving sensitivity of the switch element T realized by the same configuration as the light emitting element L is lowered. Conversely, when the switch element T is designed to increase the light receiving sensitivity of the switch element T, the light emission efficiency of the light emitting element L realized by the same configuration as the switch element T is lowered. In the present invention, since the switch element T does not have to have high light receiving sensitivity, the degree of freedom in design for increasing the light emission efficiency of the light emitting element L is improved, and the light emitting element L can efficiently emit light with less power. Thus, the power consumption of the light emitting device 10 can be reduced.

  FIG. 11 is a plan view showing a configuration of a light emitting chip 75 that constitutes the light emitting device 10 of FIG. 1 is a part surrounded by a1, a2, a3, a4, a5, and a6 in the same drawing. FIG. 11 shows a plane of the light-emitting chip 75 arranged with the light emitting direction of each light-emitting element L as a front side perpendicular to the paper surface. The light-emitting element L, the switch element T, the connecting means 14 and the signal transmission path connecting portion. 76 is shown with diagonal lines for ease of illustration.

  The light emitter chip 75 includes a first light emitter chip portion 77, a second light emitter chip portion 78, and a signal transmission path connection portion 76. The first light emitting chip portion 77 is the portion shown in FIG. 1 described above, and is the portion surrounded by a1, a2, a3, a4, a5 and a6. The second light emitting chip portion 78 has the same configuration as that of the first light emitting chip portion 77, and has a shape in which the first light emitting chip portion 77 is angularly displaced by 180 degrees around an axis extending in the Z direction perpendicular to the paper surface. Have The light emitting element array 11 of the first light emitter chip portion 77 and the second light emitter chip portion 78 is arranged linearly at the center in the width direction Y of the light emitter chip 75. Accordingly, each switching element T of the light emitting chip 75 is divided and arranged on one side and the other side of the light emitting element array 11 in the arrangement direction X of each light emitting element L and the width direction Y perpendicular to the arrangement direction X. Yes. The light emitter chip 75 is obtained by displacing a part showing the basic structure of the light emitting device 10 shown in FIG. 1 and a part showing the basic structure by 180 degrees around an axis extending in the Z direction perpendicular to the paper surface. It has a shape in which the light emitting element array 11 is arranged in a straight line.

  The switch element array 13 of the first light emitter chip portion 77 disposed on the other side in the width direction Y of the light emitting element array 11 is referred to as a first switch element array 13a and is disposed on one side of the light emitting element array 11 in the width direction. The switch element array 13 of the second light emitter chip portion 78 disposed is referred to as a second switch element array 13b. In the present embodiment, the number of switch elements T in the first and second switch element arrays 13a and 13b is selected to be equal. The first switch element array 13 a extends from the other end portion 75 b of the light emitting chip 75 in the arrangement direction X to the center portion 75 c of the arrangement direction X. The second switch element array 13 b extends from the one end portion 75 a of the light emitting chip 75 in the arrangement direction X to the center portion 75 c of the arrangement direction X.

  The first scanning start switch element T0 is provided on one side in the arrangement direction X of the first switch element array 13a, and the second scanning start switch element T0 is provided on the other side in the arrangement direction X of the second switch element array 13b. In the first switch element array 13a, the switch elements T1, T2,..., Tj−1, Tj are arranged in this order from one end portion to the other end portion in the arrangement direction X. In the second switch element array 13b, the arrangement is arranged. T1, T2,..., Tj−1, Tj are arranged in this order from the other end in the direction X toward one end.

  The light emitting chip 75 has a substantially rectangular parallelepiped shape, and a signal transmission path connecting portion 76 is provided on one surface portion 79 in the thickness direction Z.

  The light emitting element array 11 in which the light emitting element arrays 11 of the first and second light emitting chip portions 77 and 78 are arranged is formed across the one end 75a and the other end 75b of the light emitting chip 75 in the arrangement direction X. The The distance from one end of the light emitting chip 75 in the arrangement direction X to the light emitting element L at one end in the arrangement direction X, and the distance from the other end of the light emitting chip 75 in the arrangement direction X to the light emitting element L at the other end in the arrangement direction X Is selected to be the distance W7 and smaller than the distance W1 between the adjacent light emitting elements L, and is preferably about ½ of the distance W1.

  In the width direction Y, the distance W8 from the end of each of the first and second light emitter chip portions 77 and 78 opposite to the light emitting element L to one end of the light emitter chip 75 in the width direction Y is The insulating layer 17 and the light shielding layer 18 that cover the end of the switch element T opposite to the light emitting element L are selected.

First and second switching element array 13a, 13b in the arrangement direction X Niso respectively adjacent regions 80A, the 80B, provided the signal transmission line connecting unit 76 along the first and second light emitting element array 11 . The signal transmission path connection unit 76 is a part for connecting the scanning signal transmission path 15, the light emission signal transmission path 12, the start signal transmission path 16, and a bonding wire that is a signal transmission path from the outside, and is used for wire bonding. It is a bonding pad.

  The signal transmission path connection portion 76 is formed of a conductive material such as a metal material or an alloy material, and specifically, gold (Au), an alloy of gold and germanium (AuGe), and an alloy of gold and zinc. (AuZn) or the like.

  The signal transmission line connection unit 76 includes first and second start signal transmission line connection units 81a and 81b, first and second scanning signal transmission line connection units 82a and 82b, and first and second light emission signal transmission line connections. Parts 83a and 83b. The first and second start signal transmission line connection parts 81a and 81b, the first and second scanning signal transmission line connection parts 82a and 82b, and the first and second light emission signal transmission line connection parts 83a and 83b have a thickness. They are formed in a rectangular shape when viewed from one side in the direction Z, and are formed in the same size.

  In the region 80A adjacent to the one X1 in the arrangement direction of the first switch element array 13a, a first start signal transmission line connection part 81a, a first scanning signal transmission line connection part 82a, and a second light emission signal transmission line connection part 83b are provided. Are provided. A first start signal transmission line connection portion 81a is provided on one side X1 of the first switch element array 13 at a distance W9 from one end of the scan start switch element T0 in the arrangement direction X in the arrangement direction X. A first scanning signal transmission line connection part 82a is provided on one side X1 in the arrangement direction of the first start signal transmission line connection part 81a. The first scanning signal transmission line connection unit 82a includes first to third transmission line connection units 84a, 84b, and 84c. The first start signal transmission line connection part 81a and the first to third transmission line connection parts 84a, 84b, 84c are provided with an interval in the arrangement direction X, and are provided at equal intervals.

  In the present embodiment, the first transmission line connection part 84a, the second transmission line connection part 84b, and the third transmission line connection part 84c are arranged in this order from one arrangement direction X1 to the other arrangement direction X2. The start signal transmission line 16 of the first light emitter chip part 77 is connected to the first start signal transmission line connection part 81a, and the first scanning signal transmission line 15a of the first light emitter chip part 77 is connected to the first transmission line. The second scanning signal transmission path 15b of the first light emitter chip section 77 is connected to the second transmission path connection section 84b, and the third scanning signal transmission path 15c of the first light emitter chip section 77 is connected to the section 84a. , Connected to the third transmission line connection portion 84c. By connecting in this way, the dispersion | variation in the length of the transmission line from each transmission path connection part 84a, 84b, 84c to each switch element T can be suppressed.

  A second light emission signal transmission line connection portion 83b is provided at one end portion 75a of the light emitting chip 75 in the arrangement direction X on the one side in the arrangement direction X of the first scanning signal transmission line connection portion 82a. The second light emission signal transmission path connection portion 83 b is connected to the light emission signal transmission path 12 of the second light emitter chip portion 78. The second light emission signal transmission line connection portion 83b is provided at a distance W10 from one end of the light emitting chip 75 in the arrangement direction X. The distance W10 is selected to be greater than the distance W7.

  The first start signal transmission line connection part 81a, the first scanning signal transmission line connection part 82a, and the second light emission signal transmission line connection part 83b are provided outside the region where the light emitting element L is provided. A distance W11 is provided in the width direction Y. The distance W11 is selected so that when the light emitting element L emits light, the light is blocked by the signal transmission path connecting portion 76 and the light quantity does not decrease.

  In the region 80B adjacent to the other X2 of the second switch element array 13 in the arrangement direction, the second start signal transmission path connection portion 81b, the second scanning signal transmission path connection portion 82b, and the first light emission signal transmission path connection portion 83a. Are provided. A second start signal transmission line connection portion 81b is provided in the other arrangement direction X2 of the second switch element array 13 with a distance W9 from the one end in the arrangement direction X of the scanning start switch elements T in the arrangement direction X. A second scanning signal transmission line connection part 82b is provided on the other X2 side in the arrangement direction of the second start signal transmission line connection part 81b. The second scanning signal transmission line connection unit 82b includes fourth to sixth transmission line connection units 85a, 85b, and 85c. The second start signal transmission line connection part 82b and the fourth to sixth transmission line connection parts 85a, 85b, 85c are provided at intervals in the arrangement direction X. Here, they are provided at equal intervals.

  In the present embodiment, the fourth transmission line connection unit 85a, the fifth transmission line connection unit 85b, and the sixth transmission line connection unit 85c are arranged in this order from the other arrangement direction X2 toward the arrangement direction one X1. The start signal transmission line 16 of the second light emitter chip part 78 is connected to the second start signal transmission line connection part 81b, and the first scanning signal transmission line 15a of the second light emitter chip part 78 is connected to the fourth transmission line. The second scanning signal transmission path 15b of the second light emitter chip section 78 is connected to the fifth transmission path connection section 85b, and the third scanning signal transmission path 15c of the second light emitter chip section 78 is connected to the section 85a. , Connected to the sixth transmission line connection portion 85c. By connecting in this way, the dispersion | variation in the length of the transmission line from each signal transmission line connection part 76 to each switch element T can be suppressed.

  A first light emission signal transmission line connection portion 83a is provided at the other end portion 75b in the arrangement direction X of the light emitting chips 75 in the other arrangement direction X2 of the second scanning signal transmission line connection portion 82b. The first light emission signal transmission path connection portion 83 a is connected to the light emission signal transmission path 12 of the first light emitter chip portion 77. The first light emission signal transmission line connection portion 83a is provided at a distance W10 from the other end in the arrangement direction of the light emitting chips 75.

  The second start signal transmission path connection portion 81b, the second scanning signal transmission path connection portion 82b, and the first light emission signal transmission path connection portion 83a are provided outside the region where the light emitting element L is provided. A distance W11 is provided in the width direction.

  In the regions 80A and 80B in which the signal transmission path connection portion 76 is formed, the light emission signal transmission paths 12, the first to third scanning signal transmission paths 15a, 15b, and 15c, and the start signal transmission paths 16 are provided. Each signal transmission path is insulated from each other by an insulating film having electrical insulation. The signal transmission path connecting portion 76 and each signal transmission path are connected through a through hole formed in the insulating film.

As described above, each switch element array 13 of the light emitter chip 75 in the light emitting device 10 of the present embodiment has the light emitting element array 11 in the arrangement direction X of the light emitting element array 11 and the width direction Y perpendicular to the arrangement direction X. on the other hand is arranged to divide the side and the other side, the arrangement direction X against adjacent to the region 80A of each switch element array 13, the 80B, because the signal transmission line connecting unit 76 provided along the light emitting element array 11, The end of the light emitting element array 11 in the arrangement direction X can be arranged at the end of the light emitting chip 75, and the signal transmission path connecting portion 76 is arranged on one side and the other side of the light emitting element array 11 in the width direction Y. When the structure is provided, the size of the light emitting chip 75 in the direction perpendicular to the arrangement direction X can be made as small as possible.

  When the light emitting element array 11 is formed at one end in the width direction Y of the light emitting chip 75, when the light emitting chip 75 is cut out from the wafer, the shape of the long side portion that is the arrangement direction X of the light emitting elements L is emitted. In order to prevent damage to the element L, it is necessary to add a process such as dicing precisely so as not to cause chipping or lapping after cutting. In the present embodiment, since the light emitting element array 11 is formed at the central portion in the width direction Y of the light emitting chip 75, the light emitting element L is not easily damaged when cut out from the wafer, so that dicing is easy. In addition, the yield can be improved and the manufacturing process is not increased.

  FIG. 12 is a partial plan view showing a basic configuration of a light emitter chip assembly 86 having a plurality of light emitter chips 75. This figure shows a plane of the light-emitting chip assembly 86 arranged with the light emitting direction of each light-emitting element L as a front side perpendicular to the paper surface, and shows the light-emitting element array 11, the first and second switch element arrays 13a. , 13b and the signal transmission line connecting portion 76 are indicated by hatching for easy illustration.

  The light emitter chip assembly 86 includes a plurality of light emitter chips 75 shown in FIG. 11 and is configured by linearly arranging the light emitting elements L of the light emitter chips 75. The light emitting chip assembly 86 is mounted on a circuit board such as a printed wiring board with the back surface electrodes 36 of the light emitting chip 75 facing each other and the light emitting elements L of the light emitting chip 75 arranged in a straight line.

  In the plurality of light emitter chips 75, since the light emitting elements L are arranged at the one end portion 75a and the other end portion 75b in the arrangement direction X, when the light emitting element array 11 is arranged along the arrangement direction X, adjacent light emitters are arranged. The light emitting elements L at the ends in the arrangement direction X of the chips 75 can be made as close as possible, and even if the light emitting chips 75 are arranged in a line, the distance W12 between the light emitting elements L of the adjacent light emitting chips 75 is set. Since it can be within the predetermined range, it is not necessary to arrange the light emitting chips 75 in a staggered manner, and the process of arranging the light emitting chips 75 on the circuit board can be simplified. The distance W12 is selected to be about the interval W1. To be precise, W12 = W1-2 × W7.

  Further, when the light emitting chips 75 are arranged and used as an exposure device of an image forming apparatus 87 to be described later, the light emitting elements L of the respective light emitting chips 75 can be arranged in a line, so that the photoconductor via the lens array 88 is used. In the exposure to the drum 90, the optical axis shift does not occur for each light emitting chip 75. As a result, the exposure characteristics of the plurality of light emitting chips 75 to the photosensitive drum 90 can be made uniform, so that the image quality of the formed image can be improved. Further, when the photosensitive drum 90 is exposed, the plurality of light emitting chips 75 only need to read the same line data along the arrangement direction. Therefore, the light emitting device 10 has a memory function for storing a plurality of line data. The configuration of the apparatus can be simplified without necessity.

  The light emitting chip assembly 86 is used in an exposure apparatus as a line head such as an optical printer head for an electrophotographic image forming apparatus. The width W13 of the light emitting chip assembly 86 in the arrangement direction X is determined by the width of the image formed in the image forming apparatus 87.

  The signal transmission path connection portion 76 of each light emitting chip 75 is electrically connected to a portion to be connected to the circuit board by a bonding wire that is an external signal transmission path. The driving means 73 described above is mounted on the circuit board. The drive means 73 gives a signal to each signal transmission line connection part 76 via a bonding wire. By providing the drive means 73 on the circuit board on which the light emitting chip 75 is mounted, the distance of the signal transmission path from the drive means 73 to each light emitting element L, each switch element T, and the scan start switch element T0 is shortened. Thus, it is possible to suppress noise from being superimposed on a signal transmitted through the signal transmission path from the driving unit 73 to the signal transmission path connection unit 76.

  FIG. 13 is a side view showing the basic configuration of the image forming apparatus 87 having the light emitting device 10. The image forming apparatus 87 is an electrophotographic image forming apparatus, and the light emitting device 10 is used as an exposure device for the photosensitive drum 90. The light emitting device 10 includes a light emitting chip assembly 86 and driving means 73. The light emitting chip assembly 86 and the driving means 73 are mounted on a circuit board.

  The image forming apparatus 87 is an apparatus that employs a tandem system that forms four color images of Y (yellow), M (magenta), C (cyan), and K (black), and is roughly divided into four light emitting elements. The devices 10Y, 10M, 10C, and 10K, the lens arrays 88C, 88M, 88Y, and 88k as the light condensing means, the circuit board 31 on which the light emitting chip assembly 86 and the driving means 73 are mounted, and the lens array 88 are held. One holder 89C, 89M, 89Y, 89K, four photosensitive drums 90C, 90M, 90Y, 90K, four developer supply means 91C, 91M, 91Y, 91K, a transfer belt 92 as transfer means, four cleaners 93C, 93M, 93Y, 93K, four chargers 94C, 94M, 94Y, 94K, fixing means 95 and control means 96.

  Each light emitting chip assembly 86 is driven by the driving means 73 based on the color image information of each color. For example, the length W11 of the four light emitter chip assemblies 86 in the arrangement direction X is selected from 200 mm to 400 mm, for example.

  The light from the light emitting element L of each light emitting chip assembly 86 is condensed and irradiated onto the respective photosensitive drums 90C, 90M, 90Y, and 90K via the lens array 88. The lens array 88 includes, for example, a plurality of lenses respectively disposed on the optical axis of the light emitting element L, and is configured by integrally forming these lenses.

  The circuit board on which the light emitting chip assembly 86 is mounted and the lens array 88 are held by the first holder 89. By the holder 89, the light irradiation direction of the light emitting element L and the optical axis direction of the lens of the lens array 88 are aligned so as to be substantially aligned.

  Each of the photoconductor drums 90C, 90M, 90Y, and 90K is formed by, for example, attaching a photoconductor layer to the surface of a cylindrical substrate, and the outer peripheral surface receives light from each of the light emitting devices 10Y, 10M, 10C, and 10K. Then, an electrostatic latent image forming position where the electrostatic latent image is formed is set.

  In the peripheral portions of the photosensitive drums 90C, 90M, 90Y, and 90K, the exposed photosensitive drums 90C, 90M, 90Y, and 90K are sequentially exposed toward the downstream side in the rotation direction with reference to the electrostatic latent image forming positions. Developer supply means 91C, 91M, 91Y, 91K for supplying developer to the transfer belt 92, cleaners 93C, 93M, 93Y, 93K, and chargers 94C, 94M, 94Y, 94K are arranged, respectively. A transfer belt 92 that transfers an image formed on the photosensitive drum 90 with a developer onto a recording sheet is provided in common to the four photosensitive drums 90C, 90M, 90Y, and 90K.

  The photosensitive drums 90C, 90M, 90Y, and 90K are held by a second holder, and the second holder and the first holder 89 are relatively fixed. The photoconductor drums 90C, 90M, 90Y, and 90K are aligned so that the rotational axis directions of the photoconductor drum assemblies 86 and the array direction X of the light-emitting body chip assemblies 86 substantially coincide with each other.

  The recording sheet is conveyed by the transfer belt 92, and the recording sheet on which an image is formed by the developer is conveyed to the fixing unit 95. The fixing unit 95 fixes the developer transferred to the recording sheet. The photosensitive drums 90C, 90M, 90Y, and 90K are rotated by a rotation driving unit.

  The control unit 96 supplies a clock signal and image information to the driving unit 73 described above, and also rotates and drives the photosensitive drums 90C, 90M, 90Y, and 90K, developer supply units 91C, 91M, 91Y, and 91K, Each part of the transfer means 92, the charging means 94C, 94M, 94Y, 94K and the fixing means 95 is controlled.

  In the image forming apparatus 87 having such a configuration, bias light and leakage light are not generated from the light emitting device 10 used as the exposure apparatus, so that a high quality image can be formed. In addition, since the light emitting device 10 in which the switch element T and the light emitting element L by the light emitting thyristor are integrated is used for the exposure apparatus, such an exposure apparatus can be manufactured at low cost, thereby manufacturing the image forming apparatus 87. Cost can be reduced.

  As described above, according to the light emitting device 10, each switch element T can reduce the threshold voltage or threshold current by receiving light emitted from the adjacent switch element T, and each switch element T can be reduced. It is not necessary to connect a load resistor or the like connected between the diode 24 for designating the transfer direction and the power supply to the gate 24 of the first gate. Therefore, only a predetermined light emitting element L among the plurality of light emitting elements L arranged can be selectively caused to emit light with as few signal transmission paths as possible without complicating the structure of the light emitting device 10.

  Further, the scanning start switch element T0 is connected to the scanning signal transmission path 15 and emits light when a scanning signal φ is given through the scanning signal transmission path 15, and therefore supplies power necessary for the light emission of the switching element T. The transmission path and the transmission path for supplying power necessary for the scanning start switch element T0 to emit light can be shared, and a transmission path for supplying the power required for the scanning start switch element T0 is specially provided. There is no need.

  Since the scanning start switch element T0 emits light based on the scanning signal φ from the scanning signal transmission line 15 connected to the switch element T, the driving means 73 determines the timing of light emission with the switch elements T of the switch element array 13. Easy to synchronize. Further, since the scanning start switch element T0 does not emit light unless a trigger signal is given to a predetermined portion and further the scanning signal φ is not given, it is prevented from emitting light even if an undesired trigger signal is given. The

  Further, the light emitting device 10 can be easily manufactured by realizing the switch element T, the light emitting element L, and the start switch element T0 with a simple configuration in which P-type semiconductors and N-type semiconductors are alternately stacked. The switch element T, the light emitting element L, and the start switch element T0 can be formed on the substrate 31 by the same manufacturing process, and the manufacturing process of the light emitting device 10 can be reduced as much as possible.

  Further, since the switch element T, the light emitting element L, and the start switch element T0 are integrated on the same substrate 31, each element can be formed with high density. In the switch element array 13, the arrangement direction X Switch elements T adjacent to each other can be brought into close contact with each other. Accordingly, each switch element T can efficiently receive light from the adjacent switch element T, and is adjacent to the emitted switch element T even when the light emission intensity of the adjacent switch element T is small. The threshold voltage or threshold current of the switch element T can be reduced. Therefore, it is possible to reduce the power required for causing the switch element T to emit light, and to realize the light emitting device 10 with lower power consumption. Also in the light emitting element L, since the light emitting elements L adjacent in the arrangement direction can be brought into close contact with each other, the resolution of an image can be improved by using the image forming apparatus 87.

  Since each switch element T emits light in order along the arrangement direction X, the light emitting element L emits light by shielding this light by the light shielding layer 18 so as not to interfere with the light emitted by the light emitting element L. In this case, the light quantity of the light emitting element L is prevented from being reduced or increased, and a stable light quantity can be obtained. Further, since the bias light is prevented from leaking by the light shielding layer 18, the image forming apparatus 87 can form an image of good quality without degrading the image quality.

  The insulating layer 17 is provided between each light emitting element L and each switch element T and each scanning signal transmission path 15 and light emission signal transmission path 12, and each light emitting element L and each switch element T and each scanning signal transmission path. 15 and the light emission signal transmission path 12 are prevented from being short-circuited.

  Since each scanning signal transmission line 15 and the insulating layer 17 form the reflecting means, it is not necessary to form a reflecting layer or the like in order to produce the reflecting means, and it can be formed using an existing configuration. . Therefore, the reflecting means can be formed without increasing the manufacturing steps of the light emitting device 10.

  Further, in the light emitting device 10, the threshold voltage or threshold current when light from the adjacent switch element T is received is the threshold voltage or threshold current when light from the adjacent switch element T is not received. If the switch element T can be lowered to about 80% of the switch element T, the switch element T whose threshold voltage or threshold current has been reduced by light reception can be selectively emitted, so that the switch element does not have high light receiving sensitivity. The elements T can be made to emit light in order along the arrangement direction. Therefore, the light emission state of the switch element T can be sequentially shifted along the arrangement direction of the switch elements T without being influenced by the light receiving sensitivity of the switch element T, and the reliability of optical scanning is improved.

  FIG. 14 is a partial plan view showing the basic configuration of the light-emitting device 210 according to the second embodiment of the present invention. The figure shows a plane of the light emitting device 210 arranged with the light emitting direction of each light emitting element L as a front side perpendicular to the paper surface. The light emitting signal transmission path 212, the scanning signal transmission path 215, and the start signal transmission path 216 are shown. The gate 219 of the light emitting element, the gate 224 of the switch element T which is a light emitting switch element, the connection means 214, the light emitting element light shielding portion 223, and the surface electrode 225 are indicated by hatching for easy illustration.

  The light emitting device 210 includes a light emitting element array 211, a light emission signal transmission path 212, a switch element array 213, connection means 214, first and second scanning signal transmission paths 215a and 215b, and a scanning start switch element T0. , A start signal transmission path 216, an insulating layer 217, a light shielding layer 218, and a light emitting element light shielding portion 223. An optical scanning switch device is configured including the switch element array 213, first and second scanning signal transmission paths 215a and 215b, and driving means 273 described later.

  The light emitting element array 211 includes a plurality of light emitting elements L1, L2,..., Li-1, Li (the symbol i is a positive integer of 2 or more), and each light emitting element L1, L2,. 1, Li are arranged with a space W21 therebetween. Hereinafter, when the light emitting elements L1, L2,..., Li-1, Li are collectively referred to, and when an unspecified one among the light emitting elements L1, L2,. May be described. The light emitting element L is a light emitting element for exposure. In the present embodiment, the light emitting elements L are arranged at regular intervals and in a straight line. The arrangement direction X of the light emitting elements L is the left-right direction in FIG. Hereinafter, the arrangement direction X of the light emitting elements L may be simply referred to as the arrangement direction X. A direction along the light emission direction of each light emitting element L is defined as a thickness direction Z, and a direction perpendicular to the arrangement direction X and the thickness direction Z is defined as a width direction Y. The light emitting element L is formed so as to emit light having a wavelength of 600 nm to 800 nm.

  The light emitting element L is realized by a light emitting thyristor having a PNPN structure configured by alternately stacking P-type semiconductor layers and N-type semiconductor layers. The light emitting element L has a negative resistance characteristic similar to that of the reverse blocking three-terminal thyristor. The light emitting element L has a threshold voltage lower than the voltage of the light emission signal φE by giving a trigger signal to the gate 219 which is a predetermined portion, and when the light emission signal φE is given, or the current of the light emission signal φE When the threshold current is lowered and the light emission signal φE is given, light is emitted. The voltage of the light emission signal φE is a voltage applied between the anode and the cathode of the light emitting element L when the light emission signal φE is given, and the current of the light emission signal φE is light emission when the light emission signal φE is given. This is a current applied to the element L.

  The interval W21 between the light emitting elements L in the arrangement direction X and the length W22 in the arrangement direction X of the light emitting elements L are determined by the resolution of an image to be formed in the image forming apparatus on which the light emitting device 210 is mounted. When the resolution is 300 dots per inch (dpi), the interval W21 is selected to be about 45 μm (micrometer), and the length W22 is selected to be about 40 μm. The length W22 is selected so that a light emitting element light-shielding portion 223, which will be described later, can be formed between adjacent light emitting elements L. The dimension in the arrangement direction X of the light emitting elements L is selected to be smaller than the dimension in the width direction Y of the light emitting elements L. This prevents the light amount of the light emitting elements L from being insufficient when the light emitting elements L are brought close to each other in the arrangement direction X to increase the integration density.

  The light emission signal transmission path 212 is connected to each light emitting element L and transmits the light emission signal φE to each light emitting element L. The light emission signal transmission path 212 is formed by a conductive material such as a metal material and an alloy material so as to reflect light having a wavelength emitted from the light emitting element L. Specifically, the light emission signal transmission path 212 is formed of gold (Au), an alloy of gold and germanium (AuGe), an alloy of gold and zinc (AuZn), nickel (Ni), aluminum (Al), or the like. .

  The light emitting signal transmission path 212 is adjacent to the width direction Y of each light emitting element L, and the signal path extending part 221 extending along the light emitting element array 211 and the signal path extending at a distance from each other in the arrangement direction X. An element connection portion 222 that protrudes from the existing portion 221 in one width direction Y1 and is connected to one end portion in the thickness direction of each light emitting element L is provided.

  The switch element array 213 includes a plurality of switch elements T1, T2,..., Tj−1, Tj (symbol j is a positive integer of 2 or more), and each switch element T1, T2,. 1 and Tj are arranged at an interval W23 so as to receive light from adjacent switch elements T1, T2,..., Tj−1, Tj. Hereinafter, when the switch elements T1, T2,..., Tj-1, Tj are collectively referred to and when an unspecified one of the switch elements T1, T2,. May be described. In the present embodiment, the switch elements T are arranged at equal intervals. In the present embodiment, the numbers of light emitting elements L and switch elements T are equal, i.e., i and symbol j are selected to be equal. The center in the arrangement direction X of the switch elements T and the center in the arrangement direction of the light emitting elements L are provided on the same virtual plane perpendicular to the arrangement direction X.

  Each switch element T, which is a light emitting switch element, is adjacent to the light emitting element array 211 in the width direction Y, and is linearly arranged along the light emitting element array 211 so as to face the plurality of light emitting elements L. Therefore, the arrangement direction of the switch elements T is the same as the arrangement direction X of the light emitting elements L.

  Each switch element T includes a light emitting unit Ts, a light receiving unit Tr, and a connection unit Tc. When individually indicating the light emitting portion Ts of each switch element T, the reference symbol of the switch element T is described with a suffix “s”, and when the light receiving portion Tr of each switch element T is indicated individually, the switch element T When the connection part r of each switch element T is indicated individually, the reference numeral of the switch element T is indicated with a suffix “c”. For example, the switch element T1 includes a light emitting unit Ts1, a light receiving unit Tr1, and a connection unit Tc1.

  In each switch element T, the light emitting portion Ts and the light receiving portion Tr are provided adjacent to each other in the arrangement direction X. The plurality of switch elements T are arranged with the light receiving part Tr facing the light emitting part Ts of the switch element T adjacent to one side and the light receiving part Ts facing the light receiving part Tr of the switch element T adjacent to the other side. . That is, the light emitting part Ts1 of the switch element T1 faces the light receiving part Tr2 of the switch element T2, and the light emitting part Ts2 of the switch element T2 faces the light receiving part Tr3 of the switch element T3.

  The gate 227 of the light emitting part Ts, which is a predetermined part of the light emitting part Ts, and the gate 228 of the light receiving part Tr, which is a predetermined part of the light receiving part Tr, are electrically connected by the connecting part Tc.

  The light emitting portion Ts and the light receiving portion Tr of each switch element T are realized by a light emitting thyristor having a PNPN structure configured by alternately stacking P-type semiconductor layers and N-type semiconductor layers. The light emitting part Ts and the light receiving part Tr of the switch element T have the same negative resistance characteristics as the reverse blocking three-terminal thyristor. The light receiving unit Tr of the switch element T generates a trigger signal at the gate 228 of the light receiving unit Tr, which is a predetermined part by light reception. The trigger signal generated at the gate 228 of the light receiving unit Tr is given to the gate 227 of the light emitting unit Ts via the connection unit Tc. By applying a trigger signal to the gate 227 of the light emitting unit Ts, the threshold voltage or the threshold current of the light emitting unit Ts decreases. The light emitting unit Ts is connected to the scanning signal transmission line 215, and when the threshold voltage is lower than the voltage of the scanning signal φ given through the scanning signal transmission line 215 and the scanning signal φ is given, or scanning When the threshold current is lower than the current of the signal φ and the scanning signal φ is given, light is emitted. The voltage of the scanning signal φ is a voltage applied between the anode and the cathode of the light emitting portion Ts of the switch element T when the scanning signal φ is given. The current of the scanning signal φ is given by the scanning signal φ. Current applied to the light emitting portion Ts of the switch element T.

  In the present embodiment, the gate 224 of the switch element T includes a light emitting portion gate 227 and a light receiving portion gate 228.

  Since the interval W23 between the switch elements T in the arrangement direction X is limited in the manufacturing process, it is formed at least twice the height in the thickness direction Z of the switch elements T, but is selected to be less than 20 μm, preferably 10 μm. Selected below. In the present embodiment, the height of the switch element T is about 4 μm, and in this case, the interval W23 is about 8 μm. When the interval W23 is 20 μm or more, the transmission efficiency is greatly reduced.

  The dimension in the arrangement direction X of the switch elements T is selected to be smaller than the dimension in the width direction Y of the switch elements T. As a result, when each switch element T is brought close to the arrangement direction X and the integration density is increased, the light amount of the light emitting portion Ts of the switch element T is insufficient, and the light reception amount of the light receiving portion Tr is insufficient. Is prevented.

  The length W24 in the array direction X of the switch elements T is the distance W21 between the light emitting elements L in the array direction X, the length W22 in the array direction X of the light emitting elements L, and the distance between the switch elements T in the array direction X. W23. That is, the length obtained by adding the interval W21 between the light emitting elements L in the arrangement direction X and the length W22 in the arrangement direction X of the light emitting elements L, and the interval W23 between the switch elements T in the arrangement direction X and the arrangement direction of the switch elements T. The length obtained by adding the length W24 of X is selected equally.

  The connection means 214 electrically connects the gate 219 which is the predetermined portion of each light emitting element L and the gate 224 which is the predetermined portion of each switch element T corresponding to each light emitting element L. Specifically, the connecting means 214 electrically connects the gate 219 of the light emitting element L1 and the gate 224 of the switch element T1, and electrically connects the gate 219 of the light emitting element L2 and the gate 224 of the switch element T2. The gate 219 of the light emitting element Li-1 and the gate 224 of the switch element Tj-1 are electrically connected, and the gate 219 of the light emitting element Li and the gate 224 of the switch element Tj are electrically individually connected. Connecting.

  The first and second scanning signal transmission paths 215a and 215b are connected to each switch element T, and the first and second scan signals φ1 and φ2 given at different timings for each switch element T adjacent in the arrangement direction X. Is transmitted. In the present embodiment, the first scanning signal transmission path 215a transmits the first scanning signal φ1, and the second scanning signal transmission path 215b transmits the second scanning signal φ2. When generically referring to the first and second scanning signal transmission paths 215a and 215b, and when indicating an unspecified one of the first and second scanning signal transmission paths 215a and 215b, they are simply described as scanning signal transmission paths 215, When the first and second scanning signals φ1 and φ2 are collectively referred to, and when an unspecified one among the first and second scanning signals φ1 and φ2 is indicated, it may be simply referred to as a scanning signal φ. The scanning signal transmission path 215 is formed of gold (Au), an alloy of gold and germanium (AuGe), an alloy of gold and zinc (AuZn), nickel (Ni), aluminum (Al), or the like.

  The first and second scanning signal transmission paths 215a and 215b are formed so as to overlap each switch element T via the insulating layer 217 in one thickness direction Z1 of each switch element T and extend along the arrangement direction X. The first and second scanning signal transmission paths 215a and 215b are arranged with a predetermined interval W25 in the width direction Y. The predetermined interval W25 is selected as a distance that does not cause a short circuit between the first and second scanning signal transmission lines 215a and 215b, for example, 10 μm. The first and second scanning signal transmission paths 215a and 215b are intermediate portions excluding both ends of the light emitting portion Ta of the switch element T and the light receiving portion Tb in the width direction Y in the width direction Y when viewed from the Z1 side in the thickness direction. Formed over.

  The light emitting portion Ts of each switch element T has a surface electrode 225 on one end in the thickness direction Z1, that is, on the front side in the direction perpendicular to the paper surface of FIG. The first and second scanning signal transmission paths 215a and 215b are sequentially connected to the surface electrode 225 of each switch element T one by one, and are alternately connected to the switch elements T along the arranged switch elements T. Is done. That is, the first scanning signal transmission path 215a is connected to the switch elements T1, T3,..., Tj-1 (the symbol j is an integer and 2 × m, and the symbol m is a natural number), and the second scanning signal transmission path 215b is connected to the switch elements T2, T4,. Therefore, among the switch elements T, the switch element Tn arranged in the nth position (the symbol n is a positive integer that is 2 or more and j or less) in the arrangement direction X, and the switch adjacent to the arrangement direction X of the switch element Tn The elements Tn + 1 and Tn−1 are connected to different scanning signal transmission paths 215, respectively.

  The scanning start switch element T0 is realized by a light emitting thyristor having a PNPN structure in which P-type semiconductor layers and N-type semiconductor layers are alternately stacked. The scan start switch element T0 has a negative resistance characteristic similar to that of the reverse blocking three-terminal thyristor. The scanning start switch element T0 emits light when a voltage higher than a threshold voltage or a current higher than a threshold current is applied between the anode and the cathode. The scanning start switch element T0 emits light when a light emission signal φ having a voltage level equal to or higher than the threshold voltage or a current level equal to or higher than the threshold current is applied.

  The scanning start switch element T0 is arranged to irradiate light to the light receiving part Tr of the switch element T arranged at the end of the switch element array 213 in the arrangement direction X. In the present embodiment, the scanning start switch element T0 is arranged to irradiate light to the light receiving portion Tr1 of the switch element T1. One side X1 in the arrangement direction in which the scanning start switch element T0 is arranged is the upstream side of the light scanning direction in the optical scanning device. The start switch element T0 is arranged in alignment with the other end Y2 in the width direction, the other end Y2 in the width direction of each switch element T in the switch element array 213, and the arrangement direction X.

  The scanning start switch element T0 has a surface electrode 225 on one end in the thickness direction Z1, that is, on the front side in the direction perpendicular to the paper surface of FIG. The start signal transmission path 216 is connected to the surface electrode 225 of the scanning start switch element T0, and transmits the start signal φS to the scanning start switch element T0.

  The start signal transmission path 216 is provided on the switch element array 211 side of the scanning signal transmission path 215 in the width direction Y. The start signal transmission path 216 is formed of a conductive material such as a metal material and an alloy material. Specifically, the start signal transmission path 216 is formed of gold (Au), an alloy of gold and germanium (AuGe), an alloy of gold and zinc (AuZn), nickel (Ni), aluminum (Al), or the like. .

  The light emitting element L, the switch element T, and the scan start switch element T0 described above are covered with an insulating layer 217.

  The light shielding layer 218 as a light shielding means covers each switch element T from one side in the thickness direction Z of each switch element T, that is, from the front side perpendicular to the paper surface of FIG. In addition, the light emitted from the switch element T is shielded so that the light emitted from the switch element T does not interfere.

  The light emitting element light-shielding portions 223 are provided between the light emitting elements L and outside the light emitting element L in the arrangement direction X at both ends of the light emitting element array 211 in the arrangement direction X. Block the light that goes. The light emitting element light shielding portion 223 is provided apart from the light emission signal transmission path 212, and is electrically insulated from the light emission signal transmission path 212 by the insulating layer 217.

  The light emitting element L, the light emitting signal transmission path 212, the switch element T, the connection means 214, the scanning signal transmission path 215, the scanning start switch element T0, the start signal transmission path 216, the insulating layer 217, the light shielding layer 218, and the light emitting element light shielding. The part 223 is formed by being integrated on one substrate 231.

Hereinafter, each configuration of the light emitting device 210 will be described more specifically.
FIG. 15 is a partial cross-sectional view showing the basic configuration of the light emitting device 210 as viewed from the section line B1-B1 in FIG. The light emitting element L includes a first one-conductivity-type semiconductor layer 232, a first other-conductivity-type semiconductor layer 233, a second one-conductivity-type semiconductor layer 234, and the first one-conductivity-type semiconductor layer 234 formed on the one surface 231a in the thickness direction Z of the substrate 231. A second other conductivity type semiconductor layer 235 is included.

  In the present embodiment, the substrate 231 is a one-conductivity type semiconductor substrate. On the other surface 231b of the substrate 231 in the thickness direction Z, a back electrode 236 is formed. The back electrode 236 is formed over the entire surface of the other surface 231 b in the thickness direction Z of the substrate 231. The back electrode 236 is formed of a conductive material such as a metal material or an alloy material. Specifically, the back electrode 236 is formed of gold (Au), an alloy of gold and germanium (AuGe), an alloy of gold and zinc (AuZn), or the like. One surface 231a of the thickness direction Z of the substrate 231 is formed in a plane.

  In the light emitting element L, the first one-conductivity-type semiconductor layer 232 is stacked on the one surface 231a in the thickness direction Z of the substrate 231, and the first one-conductivity-type semiconductor layer 232 is disposed on the one surface 232a in the thickness direction Z. The first other conductivity type semiconductor layer 233 is laminated, the second one conductivity type semiconductor layer 234 is laminated on the one surface 233a of the first other conductivity type semiconductor layer 233 in the thickness direction Z, and the second one conductivity type A second other conductivity type semiconductor layer 235 is stacked on one surface 234a of the thickness direction Z of the semiconductor layer 234, and an ohmic contact layer 237 is formed on the one surface 235a of the thickness direction Z of the second other conductivity type semiconductor layer 235. It is constructed by stacking.

  More specifically, the substrate 231 is a semiconductor substrate capable of crystal growth such as a III-V group compound semiconductor and a II-VI group compound semiconductor, such as gallium arsenide (GaAs), indium phosphide (InP), gallium. It is formed of a semiconductor material such as phosphorus (GaP), silicon (Si), or germanium (Ge).

The first one-conductivity-type semiconductor layer 232 is formed of a semiconductor material such as gallium arsenide (GaAs), aluminum gallium arsenide (AlGaAs), or indium gallium phosphide (InGaP). The carrier density of the first one-conductivity-type semiconductor layer 232 is preferably about 1 × 10 ¹⁸ cm ⁻³ .

The first other conductivity type semiconductor layer 233 is formed of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs). The semiconductor material forming the first other-conductivity-type semiconductor layer 233 has the same energy gap as the semiconductor material forming the first one-conductivity-type semiconductor layer 232, or the first one-conductivity-type semiconductor layer 232 is formed. A material having an energy gap smaller than that of the semiconductor material is selected. The carrier density of the first other conductivity type semiconductor layer 233 is preferably about 1 × 10 ¹⁷ cm ⁻³ .

The second one-conductivity-type semiconductor layer 234 is formed of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs). The semiconductor material forming the second one-conductivity-type semiconductor layer 234 is formed with the same energy gap as the semiconductor material forming the first other-conductivity-type semiconductor layer 233 or the first other-conductivity-type semiconductor layer 233. A material having an energy gap smaller than that of the semiconductor material is selected. The carrier density of the second one conductivity type semiconductor layer 234 is such that the first one conductivity type semiconductor layer 232, the first other conductivity type semiconductor layer 233, the second one conductivity type semiconductor layer 234, and the second other conductivity type. It is desirable that it is the smallest of all the layers of the semiconductor layer 235 and is about 1 × 10 ¹⁶ cm ⁻³ to 1 × 10 ¹⁷ cm ⁻³ . The second one-conductivity-type semiconductor layer 234 can be made of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs), whereby high internal quantum efficiency can be obtained.

The second other conductivity type semiconductor layer 235 is formed of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs). The semiconductor material that forms the second other-conductivity-type semiconductor layer 235 includes the same first energy gap as that of the semiconductor material that forms the first other-conductivity-type semiconductor layer 233 and the second one-conductivity-type semiconductor layer 234. A material having an energy gap larger than that of the semiconductor material forming the other conductive type semiconductor layer 233 and the second one conductive type semiconductor layer 234 is selected. The carrier density of the second other conductivity type semiconductor layer 235 is desirably about 1 × 10 ¹⁸ cm ⁻³ .

The ohmic contact layer 237 is a semiconductor layer of the other conductivity type formed of a semiconductor material such as gallium arsenide (GaAs) or indium gallium phosphide (InGaP), and is used for performing an ohmic junction with the light emitting signal transmission path 212. is there. The carrier density of the ohmic contact layer 237 is desirably 1 × 10 ¹⁹ cm ⁻³ or more.

  Laminated body in which first one-conductivity-type semiconductor layer 232, first other-conductivity-type semiconductor layer 233, second one-conductivity-type semiconductor layer 234, second other-conductivity-type semiconductor layer 235, and ohmic contact layer 237 are laminated. Has a substantially rectangular parallelepiped shape. The first one-conductivity-type semiconductor layer 232, the first other-conductivity-type semiconductor layer 233, the second one-conductivity-type semiconductor layer 234, the second other-conductivity-type semiconductor layer 235, and the ohmic contact layer 237 are formed by the insulating layer 217. Covered.

  The insulating layer 217 is formed of a resin material having electrical insulating properties, translucency, and flatness. The insulating layer 217 is formed of polyimide, benzocyclobutene (BCB), or the like.

  A portion of the insulating layer 217 between the adjacent light emitting elements L is formed with a groove portion 238 that has a V shape in a virtual plane perpendicular to the width direction Y and reaches one surface 231a of the substrate 231. The light emitting element light shielding portion 223 is formed at 238. The light-emitting element light-shielding part 223 is formed along the surface of the groove part 238, and is provided from the one surface 231a of the substrate 231 to the side in the arrangement direction X of the ohmic contact layer 237. The light emitting element light shielding portion 223 is formed between one end and the other end in the width direction Y of the light emitting element L, and the width direction one Y1 and the other in the width direction of the light emitting element L than the end in the width direction Y of the light emitting element L. Extends to Y2. By forming such a light shielding portion 23, it is possible to prevent the adjacent light emitting element L from receiving this light when the adjacent light emitting element L emits light. Even if the adjacent light emitting element L emits light, the light emitting element is accompanied by this light emission. Since the threshold voltage or threshold current of L does not change, the light emitting element L can selectively and stably emit light.

  The element connection portion 222 of the light emission signal transmission path 212 is connected to one surface 237a of the ohmic contact layer 237 in the thickness direction Z. A through hole 239 is formed in a portion of the insulating layer 217 formed on the one surface 237a of the ohmic contact layer 237 in the thickness direction Z, and a part of the element connection portion 222 is formed in the through hole 239. Thus, the element connecting portion 222 is in contact with the ohmic contact layer 237. The through hole 239 is formed so that the center in the arrangement direction X of the light emitting elements L and the center in the width direction Y of the light emitting elements L are exposed from the insulating layer 217, and the current from the light emitting signal transmission path 212 is supplied. The light emitting element L can be made to emit light by being efficiently supplied to the central portion of the light emitting element L. In the light-emitting element L, light is generated mainly in the vicinity of the second one-conductivity-type semiconductor layer 234 near the interface between the second one-conductivity-type semiconductor layer 234 and the second other-conductivity-type semiconductor layer 235. To do.

  The length W26 in the arrangement direction X of the element connection portions 222 of the light emission signal transmission path 212 is formed to be 1/3 or less of the length W22 in the arrangement direction X of the light emitting elements L. The element connecting portion 222 covers a part of the light emission direction of the light emitting element L, but by selecting the length W26 as described above, the light emitted from the light emitting element L and blocking the light toward the thickness direction one side Z1 is blocked. As much as possible. Further, part of the light emitted from the light emitting element L and directed toward the thickness direction one Z1 and reflected by the light emission signal transmission path 212 is reflected by the light emitting element light shielding portion 223, the substrate 231 and the like, whereby the thickness direction one Z Head to.

  FIG. 16 is a partial cross-sectional view showing the basic configuration of the light emitting device 210 as seen from the section line B2-B2 of FIG. The switch element T includes a first one-conductivity-type semiconductor layer 242, a first other-conductivity-type semiconductor layer 243, a second one-conductivity-type semiconductor layer 244, and a second other-conductivity-type that are sequentially stacked on the substrate 231. Semiconductor layers 245s and 245r are included. A first one-conductivity-type semiconductor layer 242 is laminated on one surface 231a of the substrate 231, and a first other-conductivity-type semiconductor layer 243 is laminated on one surface 242a in the thickness direction of the first one-conductivity-type semiconductor layer 242. A second one-conductivity-type semiconductor layer 244 is stacked on one surface in the thickness direction of one other-conductivity-type semiconductor layer 243. A stacked body of the first one-conductivity-type semiconductor layer 242, the first other-conductivity-type semiconductor layer 243, and the second one-conductivity-type semiconductor layer 244 is formed in a substantially rectangular parallelepiped shape.

  The second one-conductivity-type semiconductor layer 244 is formed such that the thickness W27 of the one end 239r and the other end 239s in the arrangement direction X is thicker than the thickness W28 of the central portion 239c in the arrangement direction. The thickness W28 is selected to be about 50% to 90% of the thickness W27. By setting it as such thickness, the trigger signal which generate | occur | produced in the light-receiving part Tr can be more reliably transmitted to the light emission part Ts.

  At one end 239r in the arrangement direction X of the second one-conductivity-type semiconductor layer 244, at the length W29 in the arrangement direction X of the portion having the thickness W27, and at the other end 239s of the second one-conductivity-type semiconductor layer 244, The length W30 in the arrangement direction X of the portion having the thickness W27 is selected equally. The length W31 in the arrangement direction X of the portion having the thickness W28 in the central portion 239c of the second other conductive type semiconductor layer 244 is selected to be about 10 micrometers (μm).

  The second other-conductivity-type semiconductor layer 245r is stacked on the one surface 244a in the thickness direction at the one end portion 239r in the arrangement direction X of the second one-conductivity-type semiconductor layer 244, on the one surface 244a in the thickness direction. On the other surface of the other conductive type semiconductor layer 245r in the thickness direction Z, a light shielding portion forming layer 246 is laminated. The stacked body of the second other conductivity type semiconductor layer 245r and the light shielding portion forming layer 246 has a substantially rectangular parallelepiped shape.

  At the other end portion 239s in the arrangement direction X of the second one-conductivity-type semiconductor layer 244, the second other-conductivity-type semiconductor layer 245s is laminated on the one surface 244a in the thickness direction at the other end portion 239s. An ohmic contact layer 247 is stacked on one surface of the other conductive type semiconductor layer 245s in the thickness direction Z. The stacked body of the second other conductivity type semiconductor layer 245s and the ohmic contact layer 247 has a substantially rectangular parallelepiped shape. The switch element T has a substantially U shape in which a cross section in a virtual plane perpendicular to the width direction is open to one side in the thickness direction Z.

  The first one-conductivity-type semiconductor layer 242, the first other-conductivity-type semiconductor layer 243, and the second one-conductivity-type semiconductor layer 244 are shared by the light emitting unit Ts and the light receiving unit Tr. The light emitting section Ts includes a first one-conductivity-type semiconductor layer 242, a first other-conductivity-type semiconductor layer 243, a second one-conductivity-type semiconductor layer 244, a second other-conductivity-type semiconductor layer 245s, and an ohmic contact layer 247. The light receiving portion Tr includes a first one-conductivity-type semiconductor layer 242, a first other-conductivity-type semiconductor layer 243, a second one-conductivity-type semiconductor layer 244, and a second other-conductivity-type semiconductor. The layer 245r and the light shielding portion forming layer 246 are included. The thicknesses of the light emitting part Ts and the light receiving part Tr in the Z direction are selected equally, and in the width direction Y, the light receiving part Tr extends between one end and the other end of the light emitting part Ts.

  The distance between the surface facing the light receiving portion Tr of the light emitting portion Ts and the surface facing the light emitting portion Ts of the light receiving portion Tr in the arrangement direction X with respect to the light receiving portion Tr of the light emitting portion Ts included in one switch element T is as described above. The length is W31.

  The thickness of the second other conductivity type semiconductor layer 245s of the light emitting portion Ts and the thickness of the second other conductivity type semiconductor layer 245r of the light receiving portion Tr are selected to be equal, and the thickness of the ohmic contact layer 247 and the light shielding portion forming layer 246 are selected. Is selected to be equal in thickness. Further, the length in the width direction Y of the second other conductive semiconductor layer 245s of the light emitting portion Ts and the length in the width direction Y of the second other conductive semiconductor layer 245r of the light receiving portion Tr are selected to be equal to each other, and the ohmic contact layer The length in the width direction Y of 247 and the dimension in the width direction Y of the light shielding portion forming layer 246 are selected to be equal. The length in the width direction Y of the light emitting portion Ts is selected to be equal to the dimension in the width direction Y of the light receiving portion Tr.

  In the present embodiment, the light emitting portion Ts and the light receiving portion Tr of the switch element T are formed so as to be plane symmetric with respect to a virtual one plane perpendicular to the arrangement direction X.

  Each of the one conductive type semiconductor layer 242, the first other conductive type semiconductor layer 243, the second one conductive type semiconductor layer 244, the second other conductive type semiconductor layers 245s and 245r, and the ohmic contact layer 247 of the switch element T. The energy gap and the carrier density of the semiconductor material constituting the semiconductor layer are preferably designed so as to increase the light receiving sensitivity of the light receiving portion Tr of the switch element T and the light extraction efficiency and the light emitting efficiency of the light emitting portion Ts to the outside. . Specifically, the first one-conductivity-type semiconductor layer 242 and the second other-conductivity are compared with the energy gap of the semiconductor material forming the first other-conductivity-type semiconductor layer 243 and the second one-conductivity-type semiconductor layer 244. What is necessary is just to enlarge the energy gap of the semiconductor material which comprises the type | mold semiconductor layer 245. FIG. With such an energy gap, light generated in the vicinity of the interface between the second other-conductivity-type semiconductor layer 245 and the second one-conductivity-type semiconductor layer 244 can cause the first one-conductivity-type semiconductor layer 242 and the first Since the light is received by the light receiving portion Tr of the adjacent switch element T without being absorbed by the other second conductive semiconductor layer 245, the light extraction efficiency can be improved.

The first one-conductivity-type semiconductor layer 242 is formed of a semiconductor material such as gallium arsenide (GaAs), aluminum gallium arsenide (AlGaAs), or indium gallium phosphide (InGaP). The carrier density of the first one-conductivity-type semiconductor layer 242 is preferably about 1 × 10 ¹⁸ cm ⁻³ .

The first other conductivity type semiconductor layer 243 is formed of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs). The semiconductor material forming the first other-conductivity-type semiconductor layer 243 has the same energy gap as that of the semiconductor material forming the first one-conductivity-type semiconductor layer 242 or the first one-conductivity-type semiconductor layer 242 is formed. A material having an energy gap smaller than that of the semiconductor material is selected. The carrier density of the first other conductivity type semiconductor layer 243 is preferably about 1 × 10 ¹⁷ cm ⁻³ .

The second one-conductivity-type semiconductor layer 244 is formed of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs). The semiconductor material forming the second one-conductivity-type semiconductor layer 244 has the same energy gap as the semiconductor material forming the first other-conductivity-type semiconductor layer 243, or the first other-conductivity-type semiconductor layer 243 is formed. A material having an energy gap smaller than that of the semiconductor material is selected. The carrier density of the second one-conductivity-type semiconductor layer 244 is such that the first one-conductivity-type semiconductor layer 242, the first other-conductivity-type semiconductor layer 243, the second one-conductivity-type semiconductor layer 244, and the second other-conductivity-type semiconductor layer 244. It is desirable that it is the smallest of all layers of the semiconductor layer 245s and is about 1 × 10 ¹⁶ cm ⁻³ to 1 × 10 ¹⁷ cm ⁻³ . The second one-conductivity-type semiconductor layer 244 can be made of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs), whereby high internal quantum efficiency can be obtained.

The second other conductivity type semiconductor layers 245s and 245r are formed of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs). In particular, the semiconductor material forming the second other-conductivity-type semiconductor layer 245s has the same energy gap as that of the semiconductor material forming the first other-conductivity-type semiconductor layer 243 and the second one-conductivity-type semiconductor layer 244. Those having a larger energy gap than the energy gap of the semiconductor material forming the other one conductive type semiconductor layer 243 and the second one conductive type semiconductor layer 244 are selected. The carrier density of the second other conductivity type semiconductor layer 245s is preferably about 1 × 10 ¹⁸ cm ⁻³ .

  The light shielding portion formation layer 246 is a semiconductor layer of the other conductivity type formed of a semiconductor material such as gallium arsenide (GaAs) or indium gallium phosphide (InGaP), and the second one conductivity type semiconductor layer 244 is arranged in the arrangement direction X. Together with the one end portion 239r and the second other conductivity type semiconductor layer 245r, it functions as a light blocking portion that blocks light coming from the light emitting portion Ts.

The ohmic contact layer 247 is a semiconductor layer of the other conductivity type formed of a semiconductor material such as gallium arsenide (GaAs) or indium gallium phosphide (InGaP), and is for performing ohmic contact with the surface electrode 225. The carrier density of the ohmic contact layer 247 is desirably 1 × 10 ¹⁹ cm ⁻³ or more.

  The first one-conductivity-type semiconductor layer 242 of the switch element T and the first one-conductivity-type semiconductor layer 232 of the light-emitting element L are formed of the same semiconductor material and have the same thickness. The first other conductivity type semiconductor layer 243 of the switch element T and the first other conductivity type semiconductor layer 233 of the light emitting element L are formed of the same semiconductor material, and the layers are equally formed. The second one-conductivity-type semiconductor layer 244 of the switch element T and the second one-conductivity-type semiconductor layer 234 of the light-emitting element L are formed of the same semiconductor material and have the same thickness. The second other conductive semiconductor layers 245s and 245r of the switch element T and the second other conductive semiconductor layer 235 of the light emitting element L are formed of the same semiconductor material and have the same thickness. In addition, the ohmic contact layer 247 of the light emitting portion Ts of the switch element T, the light shielding portion forming layer 246 of the light receiving portion Tr, and the ohmic contact layer 237 of the light emitting element L are formed of the same semiconductor material and have the same thickness.

  In the light emitting portion Ts of the switch element T, a light emitting region that mainly generates light is formed by the second one conductive semiconductor layer 244 and the second other conductive semiconductor layer 245s, and the first one conductive layer is formed in the light receiving portion Tr. A light-receiving region mainly receiving light, that is, a phototransistor portion, is formed by the type semiconductor layer 242, the first other conductive type semiconductor layer 243, and the second one conductive type semiconductor layer 244r.

  The thickness of the first other conductivity type semiconductor layer 243 of the switch element T is selected from 50 to 1000 mm. Thus, by selecting the thickness of the first other conductivity type semiconductor layer 243, the first one conductivity type semiconductor layer 242, the first other conductivity type semiconductor layer 243, and the second one conductivity type semiconductor layer 244 are used. The current amplification factor of the formed phototransistor portion is increased and light from the outside can be efficiently received.

  On the one surface 247a of the ohmic contact layer 247 in the thickness direction Z, a surface electrode 225 is provided in ohmic contact. The surface electrode 225 is formed over the entire region excluding the peripheral portion of the one surface 247a of the ohmic contact layer 247 in the thickness direction Z. As a result, the electric field applied to each semiconductor layer of the switch element T can be made uniform, and the emission intensity of the light emitted from the switch element T can be increased. The surface electrode 225 is formed of a conductive material such as a metal material and an alloy material. Specifically, the back electrode 235 is formed of gold (Au), an alloy of gold and germanium (AuGe), an alloy of gold and zinc (AuZn), or the like. Further, the surface electrode 225 shields light traveling toward one side Z1 in the thickness direction of the switch element T by reflecting the light.

  The first one-conductivity-type semiconductor layer 242, the first other-conductivity-type semiconductor layer 243, the second one-conductivity-type semiconductor layer 244, the second other-conductivity-type semiconductor layer 245, the ohmic contact layer 247, and the surface electrode 225 are It is covered with the insulating layer 217 and is electrically insulated from the adjacent switch element T. Since the light receiving portion Tr of the adjacent switch element T faces the light emitting portion Ts and the insulating layer 217 has translucency as described above, when the light emitting portion Ts of the switch element T emits light, This light passes through the insulating layer 217 and enters the light receiving portion Tr of the switch element T adjacent to the other in the arrangement direction X. The insulating layer 217 is formed of a resin material that transmits 95% or more of light having a wavelength emitted from the switch element T. The surface of the light receiving part Tr of the predetermined switch element T facing the light emitting part Ts of the adjacent switch element T and the light receiving part Tr of the switch element T adjacent to the predetermined switch element T of the predetermined switch element T The distance from the surface facing the light emitting portion Ts is the interval W23 described above.

  As indicated by the arrows in FIG. 16, the light emitting portion Ts of the switch element T has a second one-conductivity-type semiconductor near the interface between the second one-conductivity-type semiconductor layer 244 and the second other-conductivity-type semiconductor layer 245s. Light is emitted mainly from the region near the layer 244. Further, light is emitted slightly even near the interface between the first one-conductivity-type semiconductor layer 242 and the first other-conductivity-type semiconductor layer 243. Light is emitted in all directions from the vicinity of the interface between the second one-conductivity-type semiconductor layer 244 and the second other-conductivity-type semiconductor layer 245s of the light-emitting portion Ts.

  The direction from the vicinity of the interface between the second one-conductivity-type semiconductor layer 244 and the second other-conductivity-type semiconductor layer 245s of the light-emitting portion Ts toward the light-receiving portion Tr of the switch element T having the light-emitting portion Ts, that is, the arrangement direction one X1 The light directed toward is shielded by the one end portion 239r in the arrangement direction X of the second one-conductivity-type semiconductor layer 244 constituting the light-receiving portion Tr, the second other-conductivity-type semiconductor layer 245r, and the light-shielding portion formation layer 246.

  The length W29 in the arrangement direction of the one end 239r in the arrangement direction X of the second one-conductivity-type semiconductor layer 244, the second other-conductivity-type semiconductor layer 245r, and the light-shielding portion formation layer 246 is selected to be 20 μm or more, preferably Is selected to be 30 μm or more, and is selected to be less than ½ of the length W24 of the switching element T in the width direction Y. When the dimension W29 is less than 20 μm, light is transmitted through the one end 239r in the arrangement direction X of the second one-conductivity-type semiconductor layer 244, the second other-conductivity-type semiconductor layer 245r, and the light-shielding portion formation layer 246. When the length W24 of the switch element T in the width direction Y is greater than or equal to ½, the volume of the light emitting portion Ts in the switch element T is reduced, and a sufficient amount of light is emitted when the light emitting portion Ts emits light. It may be difficult to obtain. Therefore, by selecting the length W29 in the arrangement direction to be 20 μm or more, preferably 30 μm or more, and less than ½ of the length W24 in the width direction Y of the switch element T, the light coming from the light emitting portion Ts is transmitted. Therefore, the light can be reliably shielded, and the volume of the light emitting portion Ts in the switch element T can be increased. Further, if the volume occupied by the light emitting portion Ts in the switch element T is increased, the amount of light when the light emitting portion Ts emits light can be improved.

  In particular, in the light receiving portion Tr, at one end portion 239r of the second one-conductivity-type semiconductor layer 244, a portion projecting in the thickness direction one Z1 from the central portion 239c, a second other-conductivity-type semiconductor layer 245r, and a light-shielding portion formation When the light emitting portion Ts emits light by blocking light coming from the light emitting portion Ts with the layer 246, the switch element T adjacent to one side in the arrangement direction X of the switch elements T having the emitted light emitting portion Ts. In the light emitting unit Ts, the amount of received light can be reduced, and the threshold voltage or the threshold current can be prevented from decreasing due to the received light.

  In the present embodiment, the first one-conductivity-type semiconductor layer 242, the first other-conductivity-type semiconductor layer 243, and the second one-conductivity-type semiconductor layer 244 are commonly used in the light emitting unit Ts and the light receiving unit Tr. The connecting portion Tc is formed including the central portion 239c of the second one-conductivity-type semiconductor layer 244. Since the first one-conductivity-type semiconductor layer 242, the first other-conductivity-type semiconductor layer 243, and the second one-conductivity-type semiconductor layer 244 of the light-emitting portion Ts and the light-receiving portion Tr are integrally formed, the light-emitting portion The configuration of Ts and the light receiving portion Tr is further simplified, and the light emitting portion Ts and the light receiving portion Tr are further easily manufactured. Since the central portion 239c of the second one-conductivity-type semiconductor layer 244 functions as the connection portion Tc, it is not necessary to separately form the connection portion Tc, and the configuration of the switch element T can be further simplified, thereby producing The number of steps can be reduced as much as possible, and productivity can be improved.

  In the switch element T, when the light emitting part Ts of the switch element T adjacent in the arrangement direction one X1 emits light, the light is received by the light receiving part Tr. When the light receiving unit Tr receives light, carriers corresponding to the received light intensity are generated in each semiconductor layer of the light receiving unit Tr by light excitation. Since the gate 228 of the light receiving unit Tr, the gate 227 of the light emitting unit Ts, and the connection unit Tc are all integrally formed by the second one-conductivity-type semiconductor layer 244, the light receiving unit Tr can be coupled to the light receiving unit Tr by photoexcitation. When a carrier as a trigger signal is generated in the gate 228, the trigger signal is given to the gate 227 of the light emitting unit Ts via the connection unit Tc, and the carrier is also generated in the light emitting unit Ts. The electrons accumulated in the second one-conductivity-type semiconductor layer 244 due to the generation of carriers lowers the Fermi level of the second one-conductivity-type semiconductor layer 244, whereby the first other-conductivity-type semiconductor layer 243 and the first The avalanche phenomenon is likely to occur at the junction with the one-conductivity-type semiconductor layer 244, and the threshold voltage or threshold current in the light emitting portion Ts can be reduced.

  By forming the insulating layer 217 with a resin material having flatness, when the insulating layer 217 is formed, the resin material is also filled between the switch elements T, and the insulating layer 217 is interposed between the switch elements T. Can be reliably formed. The insulating layer 217 is formed by applying a resin material and curing the resin material. By forming the insulating layer 217 from polyimide and benzocyclobutene (BCB) or the like, the insulating layer 217 can be reliably formed in this gap even if the interval W23 between the switch elements T is selected as described above. The first one-conductivity-type semiconductor layer 242, the first other-conductivity-type semiconductor layer 243, the second one-conductivity-type semiconductor layer 244, the second other-conductivity-type semiconductor layers 245s and 245r, the light-shielding portion formation layer 246, the ohmic structure The insulating layer 217 can be formed in close contact with the contact layer 247, the surface electrode 225, and the substrate 231. If the insulating layer 217 is peeled off from the surface of the switch element T, light may be reflected by the interface of the peeled portion, and the amount of light received from the adjacent switch element T may be reduced. There is no such problem.

  One of the first and second scanning signal transmission lines 215a and 215b is connected to one surface 225a of the thickness direction Z of the surface electrode 225. A through hole 249 is formed in a portion of the insulating layer 217 formed on the one surface 225a of the thickness direction Z of the surface electrode 225, and the first and second scanning signal transmission lines 215a are formed through the through hole 249. , 215b are connected, and the switch element T and the other scanning signal transmission paths 215 of the first and second scanning signal transmission paths 215a, 215b are electrically insulated by the insulating layer 217. Since the switch element T is covered with the insulating layer 217, the first and second scanning signal transmission paths 215a and 215b can be stacked on one side Z1 in the thickness direction of the switch element T.

  In the present embodiment, one conductivity type is N-type, and the other conductivity type is P-type. In the light-emitting element L and the switch element T, when one conductivity type is N-type and the other conductivity type is P-type, the light-emitting signal transmission path 212 and the scanning signal transmission path 215 correspond to the anodes of the light-emitting elements L and the switch elements T, respectively. When the cathode potential is 0 volt (V), a positive power source can be used as a power source for applying voltage or current to each light emitting element L and each switch element T, which is preferable. In the present embodiment, in the light emitting element L, the light emission signal transmission path 212 functions as an anode terminal, and the back electrode 236 functions as a cathode terminal. In the switch element T, the ohmic contact layer 247 and the front electrode 225 function as an anode terminal, and the back electrode 236 functions as a cathode terminal. The second other-conductivity-type semiconductor layer 245s is not directly connected to the scanning signal transmission line 215, but is connected via an anode terminal including the ohmic contact layer 247 and the surface electrode 225, so that the light emitting unit Ts and the scanning signal transmission line 215 are connected. The contact resistance can be reduced as much as possible at the connection portion, and the heat generation in the light emitting portion Ts of the switch element T can be suppressed, and the power consumption can be suppressed.

  On one side in the thickness direction Z of each switch element T, the insulating layer 217 and the scanning signal transmission path 215 are covered with a light shielding layer 218. As the material of the light shielding layer 218, various materials can be used as long as they have electrical insulating properties and absorb light of a wavelength emitted from the switch element T almost completely with a thickness of about 2 μm to 3 μm. is there. In this embodiment mode, the light shielding layer 218 is formed of green polyimide. The thickness of the light shielding layer 218 is selected to be about 5 μm to 10 μm.

  The light emitted from the light emitting portion Ts of the switch element T and traveling in one direction Z1 in the thickness direction is caused by the interface between the insulating layer 217 and the scanning signal transmission path 215, the scanning signal transmission path 215, and the interface between the insulating layer 217 and the light shielding layer 218. It is reflected or absorbed by the light shielding layer 218. Each scanning signal transmission path 215 and the insulating layer 217 form a reflecting means. This prevents the light from the switch element T from interfering with the light emitted from the light emitting element L in the thickness direction one Z1. Therefore, when the light emitting device 210 is used as an exposure device of an image forming apparatus, image deterioration is not caused by leakage light from the switch element T, and an excellent quality image can be formed.

  As described above, the insulating layer 217 and the scanning signal transmission path 215 function as reflecting means, and can reflect the light emitted from the light emitting part Ts of the switch element T to the light receiving part Tr facing the light emitting part Ts. . This improves the transmission efficiency of light transmitted from the light emitting part Ts of one switch element T to the light receiving part Tr of the switch element T adjacent to the arrangement direction X arranged with the light receiving part Tr facing the light emitting part Ts. Can be made. Accordingly, the trigger signal can be reliably generated in the light receiving portion Tr of the switch element T adjacent to the light emitting switch element T, and the threshold voltage of the light emitting portion Ts of the switch element T adjacent to the light emitting switch element T or The threshold current can be reliably reduced, and the optical scanning of the switch element T can be performed more stably. In addition, since the threshold voltage and threshold current of the light emitting portion Ts of the switch element T adjacent to the switch element T having the light emitting portion Ts emitted can be quickly reduced, the light emitting portion Ts of the switch element T is arranged in the arrangement direction. The scanning speed of the light emitting part Ts of the switch element T that emits light in order can be improved. Further, even if the light amount emitted from the light emitting portion Ts of the switch element T is small, the threshold voltage or threshold current of the adjacent switch element T can be lowered, so that the power necessary for the light emission of the switch element T is made as much as possible. Optical scanning can be performed while suppressing power consumption of the apparatus. In order to produce such a reflection means, it is not necessary to form a reflection layer or the like in particular, and it can be formed by using the insulating layer 217 and the scanning signal transmission line 215 which are existing structures. Therefore, the reflecting means can be formed without increasing the number of manufacturing steps of the light emitting device 210.

  FIG. 17 is a partial cross-sectional view showing the basic configuration of the light emitting device 210 as seen from the section line B3-B3 in FIG. The light emitting element L and the switch element T are arranged adjacent to each other in the width direction Y. The ends of the first one-conductivity-type semiconductor layer 232, the first other-conductivity-type semiconductor layer 233, and the second one-conductivity-type semiconductor layer 234 of the light-emitting element L near the switch element T The light emitting element connection portion 251 is formed by projecting toward the switch element T from the end of the conductive semiconductor layer 235 and the ohmic contact layer 237 near the switch element T. The end of the switch element T near the light emitting element L of the first one-conductivity-type semiconductor layer 242, the first other-conductivity-type semiconductor layer 243, and the second one-conductivity-type semiconductor layer 244 is The other conductive type semiconductor layers 245s and 245r, the light shielding part forming layer 246, and the ohmic contact layer 237 protrude toward the switch element T from the ends of the light emitting element L, thereby forming the switch element connecting part 252.

  Of the second one-conductivity-type semiconductor layer 234 of the light-emitting element L, the portion 234A constituting the light-emitting element connection portion 251 is formed to be smaller in thickness than the portion 234B where the second other-conductivity-type semiconductor layer 235 is stacked. The Of the second one-conductivity-type semiconductor layer 244 of the light-emitting element switch T, the portion 244A constituting the switch-element connection portion 252 has a smaller thickness than the portion 244B where the second other-conductivity-type semiconductor layer 245 is stacked. It is formed.

  The light emitting element connection portion 251 of the light emitting element L and the switch element connection portion 252 of the switch element T corresponding to the light emitting element L are integrally formed. That is, the first one-conductivity-type semiconductor layer 232 of the light-emitting element L and the first one-conductivity-type semiconductor layer 242 of the switch element T are integrally formed, and the first other-conductivity-type semiconductor layer of the light-emitting element L is formed. 243 and the first other conductivity type semiconductor layer 233 of the switch element T are integrally formed, the second one conductivity type semiconductor layer 234 of the light emitting element L and the second one conductivity type semiconductor of the switch element T The layer 244 is integrally formed.

  The second one-conductivity-type semiconductor layer 234 of the light-emitting element L is the gate 219 of the light-emitting element L, and the second one-conductivity-type semiconductor layer 244 of the switch element T is the gate 224 of the switch element T. The gate 224 of the switch element T is also a gate 227 of the light emitting unit Ts and a gate 228 of the light receiving unit Tr. The connection means 214 includes a portion of the second one-conductivity-type semiconductor layer 234 in the light-emitting element connection portion 251 and a portion of the second one-conductivity-type semiconductor layer 244 in the switch element connection portion 252. Therefore, the connection means 214 electrically connects the light emitting elements L and the gates of the light emitting portions Ts of the switch elements T to each other. By configuring the connection means 214 in this manner, the number of manufacturing steps can be reduced, and the light emitting element L and the switch element T can be brought closer to each other in the width direction Y, so that the light emitting device 210 can be downsized. be able to.

  The resistance value of the connecting means 214 is selected to be 1 kΩ (ohms) or less. If the resistance value is too high, the trigger signal from the switch element T to the light emitting element L is attenuated, but the trigger signal from the switch element T to the light emitting element L is selected by selecting the resistance value of the connecting means 214 within the above range. Is transmitted without attenuation. The length in the width direction Y of the connection means 214, in other words, the length Wc in the width direction Y of the portion including the light emitting element connection portion 251 and the switch element connection portion 252 is selected to be 10 μm to 100 μm.

  In the region between the light emitting element L and the switch element T, an insulating layer 217 is formed so as to be stacked on the connecting means 214. Of the insulating layer 217, the thickness of the portion laminated on the connection means 214 is slightly larger than the distance from one surface of the connection means 214 to the one surfaces 237 a and 247 a of the ohmic contact layers 237 and 247 in the thickness direction Z. It is formed. Of the insulating layer 217, one surface of the portion laminated in the thickness direction Z of the light emitting element L and the switch element T is retracted closer to the substrate 231 than the surface of the portion laminated in the thickness direction Z of the light emitting element L and switch element T. And a planar portion 217 a parallel to one surface 231 a of the substrate 231. The planar portion 217a is formed in a region between the light emitting element L and the switch element T and extending from an end near the light emitting element L to an end near the switch element T.

  In the width direction Y, the signal path extending portion 221 of the light emission signal transmission path 212 is formed by laminating on the end portion closer to the light emitting element L than the center of the plane portion 217a in the width direction Y in the plane portion 217a. Is done. The light shielding layer 218 extends to the light emitting element L side along the surface of the insulating layer 217 and covers the end of the signal path extending portion 221 on the switch element T side.

  The ends of the second other conductive type semiconductor layer 245 and the ohmic contact layer 247 of the switch element T near the light emitting element L are covered with a light shielding layer 218 stacked on the insulating layer 217. Thereby, when the light emitting part Ts of the switch element T emits light, the light traveling in the light emitting direction of the light emitting element L can be shielded. Since the light emitting portion Ts of each switch element T emits light in order along the arrangement direction, the light is blocked by the light blocking layer 218 that is a light blocking means, so as not to interfere with the light emitted by the light emitting element L. When the light emitting element L emits light, the light quantity of the light emitting element L is prevented from being reduced or increased, and a stable light quantity can be obtained. Further, the end of the switch element T opposite to the light emitting element L is covered with a light shielding layer 218 with an insulating layer 217 interposed therebetween.

  FIG. 18 is a partial cross-sectional view showing the basic configuration of the light emitting device 210 as seen from the section line B4-B4 in FIG. Since the scanning start switch element T0 and the switch element T have the same configuration, the same parts are denoted by the same reference numerals, and redundant description may be omitted.

  In the scanning start switch element T0, the first one-conductivity-type semiconductor layer 262 is stacked on the one surface 231a in the thickness direction Z of the substrate 231, and the one surface of the first one-conductivity-type semiconductor layer 262 in the thickness direction Z is stacked. The first other conductivity type semiconductor layer 263 is stacked on the second electrode 262a, the second one conductivity type semiconductor layer 264 is stacked on the one surface 263a in the thickness direction Z of the first other conductivity type semiconductor layer 263, and the second The second other-conductivity-type semiconductor layer 265 is stacked on one surface 264a of the one-conductivity-type semiconductor layer 264 in the thickness direction Z, and ohmic is formed on the one surface 265a of the second other-conductivity-type semiconductor layer 265 in the thickness direction Z. A contact layer 267 is stacked, and a surface electrode 225 is stacked on one surface 267 a of the ohmic contact layer 267 in the thickness direction Z. Lamination of first one-conductivity-type semiconductor layer 262, first other-conductivity-type semiconductor layer 263, second one-conductivity-type semiconductor layer 264, second other-conductivity-type semiconductor layer 265, ohmic contact layer 267, and surface electrode 225 The body has a substantially rectangular parallelepiped shape. Further, the dimension in the width direction Y of the scanning start switch element T0 is formed larger than the dimension in the width direction of the switch element T. The other end of the scanning start switch element T0 in the width direction Y is aligned with the other end of the switch element T in the width direction Y.

  The first one-conductivity-type semiconductor layer 262 of the scanning start switch element T0 and the first one-conductivity-type semiconductor layer 242 of the switch element T are formed of the same semiconductor material and have the same thickness. The first other conductive semiconductor layer 263 of the scanning start switch element T0 and the first other conductive semiconductor layer 243 of the switch element T are formed of the same semiconductor material and have the same thickness. The second one-conductivity-type semiconductor layer 264 of the scan start switch element T0 and the second one-conductivity-type semiconductor layer 244 of the switch element T are formed of the same semiconductor material and have the same thickness. The second other conductive semiconductor layer 265 of the scanning start switch element T0 and the second other conductive semiconductor layer 245 of the switch element T are formed of the same semiconductor material and have the same thickness. The ohmic contact layer 267 of the scanning start switch element T0 is formed of the same semiconductor material as the ohmic contact layer 247 of the switch element T and has the same thickness.

  The scanning start switch element T0 is covered with an insulating layer 217 and a light shielding layer 218. A scanning signal transmission path 215 and a start signal transmission path 216 are formed by laminating on an insulating layer 217 laminated on one side Z1 in the thickness direction of the scanning start switch element T0. The start signal transmission path 216 is provided at an interval in a region near the light emitting element L of the first scanning signal transmission path 215a. A through hole 269 is formed in the insulating layer 217 on one side in the thickness direction of the scanning start switch element T0, and the start signal transmission path 216 is laminated, and the start signal transmission path 216 is formed in the through hole 269. A part is formed, and the start signal transmission path 216 is connected to the surface electrode 225 of the scanning start switch element T0 through the through hole 269. The scanning start switch element T 0, the scanning signal transmission path 215, and the start signal transmission path 216 are covered with a light shielding layer 218.

  Each light emitting element L, each switch element T, and scan start switch element T0 are formed on one surface 231a of the substrate 231 on the first one-conductivity-type semiconductor layers 232, 242, 262, and the first other-conductivity-type semiconductor layer 233. , 243, 263, the second one-conductivity-type semiconductor layers 234, 244, 264, the second other-conductivity-type semiconductor layers 235, 245s, 245r, 265, the light shielding layer forming portion 236, and the ohmic contact layers 237, 247, 267 are sequentially stacked by epitaxial growth, chemical vapor deposition (CVD), or the like, and then patterned and etched by photolithography. Therefore, since the light emitting element L, the switch element T, and the scan start switch element T0 can be formed simultaneously in a series of manufacturing processes, the manufacturing cost can be reduced. After forming each semiconductor layer, a conductor layer is formed by vapor deposition or the like, and patterned and etched by photolithography to form the surface electrode 225.

  After the surface electrode 225 is formed, the insulating layer 217 is spin-coated with the above-described resin material such as polyimide, and then the applied resin material is cured, and the light emission signal transmission path 212 and the first and second scanning signal transmissions are performed. The through holes 239, 249, and 269 necessary for connection to the paths 215a and 215b, the start signal transmission path 216, the light emitting element L, the switch element T, or the scan start switch element T0 are patterned and etched by photolithography. It is formed.

  The light-emitting signal transmission path 212, the first and second scanning signal transmission paths 215a and 215b, the start signal transmission path 216, and the light-emitting element light-shielding portion 223 are made conductive by an evaporation method or the like after the insulating layer 17 is formed. After the material is stacked on the surface of the insulating layer 217, it is simultaneously formed by patterning and etching by photolithography. Therefore, the light emitting signal transmission path 212, the first and second scanning signal transmission paths 215a and 215b, the start signal transmission path 216, and the light emitting element light-shielding portion 223 are formed to have substantially the same thickness.

  The forward voltage-current characteristics, which are the relationship between the anode voltage and the anode current, of the light emitting element L, the light emitting part Ts of the switch element T, the light receiving part Tr, and the scanning start switch element T0 are shown in FIG. This is the same as the graph shown in FIG. The light emitting element L, the light emitting part Ts of the switch element T, the light receiving part Tr, and the scanning start switch element T0 include the characteristic curve representing the voltage-current characteristic, the point b in the off state where the load line 72 intersects, the characteristic curve and the load. Transition is made to the point a in the on state where the line 72 intersects.

The initial threshold voltage (breakover voltage) of the light emitting part Ts and the light receiving part Tr of the light emitting element L and the switch element T, and the threshold voltage of the scanning start switch element T0 are defined as V _BO . The initial threshold voltage is a threshold voltage in a state where no trigger signal is applied to the gate 219 in the light emitting element L, and a trigger signal is applied to the gate 227 of the light emitting section Ts in the light emitting section Ts of the switch element T. This is the threshold voltage when not being received, and is the threshold voltage when the light receiving portion Tr of the switch element T is not receiving light.

In the light emitting element L and the light emitting unit Ts, the threshold voltage is changed from V _BO by applying a trigger signal to the gates 219 and 227 and receiving light in the light receiving unit Tr, as indicated by an arrow P1 in FIG. The threshold voltage drops to V _TH which is a voltage smaller than V _BO .

FIG. 19 is a circuit diagram showing a partial equivalent circuit showing the basic configuration of the light emitting device 210 shown in FIG. The light emitting device 210 further includes a driving unit 273. The driving unit 273 is connected to the first and second scanning signal transmission paths 215a and 215b, the light emission signal transmission path 212, and the start signal transmission path 216, and scans the first and second scanning signal transmission paths 215a and 215b. The signal φ is applied, the start signal φS is applied to the start signal transmission path 216, and the light emission signal φE is applied to the light emission signal transmission path 212. The driving means 73 includes a driving driver IC (
Integrated circuit).

  The driving means 273 receives a reference clock pulse signal from the outside, and outputs the first and second scanning signals φ1 and φ2 and the start signal φS in synchronization with the clock pulse signal, and transmits the scanning signal. Are provided to the path 215 and the start signal transmission path 216, respectively. The clock pulse signal is given from the control means of the image forming apparatus. The clock cycle of the clock pulse signal is selected to be longer than the control cycle in the control means of the image forming apparatus. Further, the driving unit 273 outputs the light emission signal φE based on the image information given together with the clock pulse signal, and gives it to the light emission signal transmission path 212.

  The first and second scanning signal transmission paths 215a and 215b are connected to a resistance element Rφ connected in series with each switch element T, and the driving means 273 performs first and second scanning via the resistance element Rφ. Connected to the signal transmission paths 215a and 215b. The resistance element Rφ has a function as a voltage dividing resistor that prevents the overcurrent from flowing from the driving unit 273 to the scanning signal transmission path 215 and divides the voltage applied to each switch element T.

  Also, the light emitting signal transmission path 212 is connected to a resistance element Rφ connected in series with each light emitting element L, and the driving means 273 is connected to the light emission signal transmission path 212 via the resistance element Rφ. The resistance element Rφ has a function as a voltage dividing resistor that prevents the overcurrent from flowing from the driving unit 273 to the scanning signal transmission path 215 and divides the voltage applied to each light emitting element L.

  Also, the start signal transmission line 216 is connected to the resistance element Rφ so as to be in series with the start switch element T0, and the driving means 273 is connected to the start transmission line 216 via the resistance element Rφ.

  FIG. 20 shows that the drive means 273 gives a start signal φS to the start signal transmission path 216, a first scanning signal φ1 to give to the first scanning signal transmission path 215a, a second scanning signal φ2 to give to the second scanning signal transmission path 215b, 4 is a waveform diagram showing a light emission signal φE applied to the light emission signal transmission path 212, the light emission intensity of the light emitting element L1, and the light emission intensity of the scanning start switch element T0 and the switch elements T1 to T4. The light emission intensity of the light emitting element L1, the scanning start switch element T0, and the switch elements T1 to T4 indicates that light is emitted when the level is high (H), and indicates that no light is emitted when the level is low (L). . In FIG. 20, the horizontal axis represents time, and represents the elapsed time from the reference time.

  For the start signal φS, the first and second scanning signals φ1, φ2 and the light emission signal φE, the vertical axis represents the signal level. The signal level represents the magnitude of voltage or current. When the start signal φS, the first and second scanning signals φ1, φ2 and the light emission signal φE are at a high (H) level, a high voltage or high current is applied to the signal transmission line. When the start signal φS, the first and second scanning signals φ1, φ2 and the light emission signal φE are at a low (L) level, a low voltage or a low current is supplied to the signal transmission line. When the start signal φS, the first and second scanning signals φ1, φ2, and the light emission signal φE are at the L level, the voltage or current supplied to the transmission line is smaller than the threshold voltage or threshold current of each element. In the case of voltage, the high level is, for example, 3 volts (V) to 10 volts (V). In the case of voltage, the low level is, for example, 0 (zero) volts (V).

  In the present embodiment, the start signal φS at the H level, the first and second scanning signals φ1, φ2 and the light emission signal φE are set to 5 volts (V), for example, and the L level start signal φS, first and second The voltages of the second scanning signals φ1 and φ2 and the light emission signal φE are set to 0 volts (V), for example. The waveforms of the first and second scanning signals φ1 and φ2 are the same and have different phases.

  In the light emitting device 210, the light emission state of the switch element T is transferred along the arrangement direction X in order to reduce the threshold voltage or threshold current of the light emitting element L to emit light.

  Hereinafter, the operation of the driving unit 273 will be described. First, at time t0, the driving unit 273 sets the start signal φS, the first and second scanning signals φ1 and φ2, and the light emission signal φE to a low level. By setting the start signal φS to the low level, the scanning start switch element T0 does not emit light. When the signal level is changed from the low level to the high level for the light emission signal φE, the start signal φS, and the scanning signal φ, the driving unit 273 changes the signal level to the high level until the signal level is changed from the high level to the low level next time. To maintain. Further, when the signal level of the light emission signal φE, the start signal φS, and the scanning signal φ is changed from the high level to the low level, the driving unit 273 sets the signal level to the low level until the signal level is changed from the low level to the high level. To keep.

  At time t1, the driving unit 273 changes only the start signal φS from the low level to the high level. At time t1, the first and second scanning signals φ1, φ2 and the light emission signal φE are at a low level. As a result, the scanning start switch element T0 is turned on, that is, turned on and emits light. The high level signal of the start signal φS is a voltage or current larger than the threshold voltage or threshold current of the scan start switch element T0.

  The light of the scanning start switch element T0 is most strongly incident on the light receiving part Tr1 of the switch element T1 arranged at the end of the adjacent switch element array 213 in the arrangement direction X. In the other switch elements T of the switch element array 213, the intensity of light emitted from the scan start switch element T0 is smaller as the switch element T is arranged in the arrangement direction X at a position separated from the scan start switch element T0. Become. In the light receiving portion Tr of the switch element T, when light is received, carriers corresponding to the received light intensity are generated in each semiconductor layer by photoexcitation. Since the gate 228 of the light receiving portion Tr, the gate 227 of the light emitting portion Ts, and the connection portion Tc are all integrally formed by the second one-conductivity-type semiconductor layer 244, the light receiving portion Tr gates by photoexcitation in the light receiving portion Tr. When a carrier as a trigger signal is generated in 228, this trigger signal is given to the gate 227 of the light emitting unit Ts via the connection unit Tc, and a carrier is also generated in the light emitting unit Ts. The electrons accumulated in the second one-conductivity-type semiconductor layer 244 due to the generation of carriers lowers the Fermi level of the second one-conductivity-type semiconductor layer 244, whereby the first other-conductivity-type semiconductor layer 243 and the first The avalanche phenomenon is likely to occur at the junction with the one-conductivity-type semiconductor layer 244, and the threshold voltage or threshold current in the light emitting portion Ts can be reduced.

  For this reason, when the light receiving portion Tr of the switch element T receives light, the threshold voltage or the threshold current of the light emitting portion Ts connected to the received light receiving portion Tr and the connecting portion Tc is reduced, and the light receiving portion. As the light intensity received by Tr increases, the threshold voltage or threshold current drop of the light emitting part Ts connected by the received light receiving part Tr and the connection part Tc increases.

  Next, the transfer of the light emission state from the scanning start switch element T0 to the switch element T1 will be described. When the scanning start switch element T0 emits light, this light is received by the light receiving portion Tr1 of the switch element T1, and the threshold voltage of the light emitting portion Ts1 of the switch element T1 is lowered as described above.

After the elapse of time t1, the threshold voltage of the light emitting unit Ts1 of the switch element T1 is V _TH (T1) at time t2. The switch elements T1, T3,..., Tj-1 are connected to the first scanning signal transmission path 215a, but the switch elements T3,..., Tj-1 are sufficiently separated from the scanning start switch element T0. Therefore, even if light from the scanning start switch element T0 is received, the light is weak, so that the threshold voltage of the light emitting portion Ts hardly changes.

  At time t2, the driving unit 273 changes the first scanning signal φ1 from the low level to the high level. At time t2, the start signal φS is at a high level, and the second scanning signal φ2 and the light emission signal φE are at a low level. The high level of the first scanning signal φ1 is the threshold voltage of the light emitting portion Ts of the other switch elements T3,..., Tj−1 except the light emitting portion Ts1 of the switch element T1 connected to the first scanning signal transmission path 215a. A voltage higher or higher than the lowest threshold current is selected.

  The scanning signal transmission path 215 is connected to the scanning signal transmission path 215 to which the light emitting section Ts of the switch element T whose threshold voltage or threshold current has been lowered by receiving light from the light emitting section Ts of the adjacent switch element T is received. When a scanning signal φ having a voltage or current higher than the minimum value of the threshold voltage or threshold current of the light emitting portion Ts of the other switch element T connected to 215 is given, the scanning signal φ is passed through the resistance element Rφ. A voltage divided by the resistance element Rφ is applied to the scanning signal transmission path 215 and to the switch element T. A voltage divided by the resistance element Rφ is gradually applied to each switch element T, and among the plurality of switch elements T connected to the same scanning signal transmission path 215, the adjacent switch element T The voltage or current applied to the light emitting part Ts of the switch element T having the light receiving part Tr that has received the light from the earliest becomes the threshold voltage or threshold current of the light emitting part Ts of the switch element T earliest. Accordingly, only the light emitting portion Ts of the switch element T having the lowest threshold voltage or threshold current emits light, and the other switch elements T do not emit light.

  Thereby, at time t2, the light emitting portion Ts1 of the switch element T1 is turned on, that is, turned on and emits light.

  After the light emitting unit Ts1 of the switch element T1 is turned on, the driving unit 73 sets the start signal φS to the low level at time t3. Accordingly, the scanning start switch element T0 is turned off, that is, turned off and turned off.

  In this way, the light emission state transitions from the scanning start switch element T0 to the switch element T1. At time t3, the driving unit 273 changes the start signal φS from the high level to the low level, and thereafter maintains the low level until the light emission of the switch element Tj is completed. When the start switch element T0 is not caused to emit light, the start signal φS can be kept at a low level and the low level voltage is set to 0 (zero) volts (V), so that power is not consumed in the non-light emitting state. The time for setting the start signal φS to the high level is shorter than the time for setting the first scanning signals φ1 and φ2 to the high level. Since the scan start switch element T0 is used only for lowering the threshold voltage or threshold current of the light emitting portion Ts1 of the switch element T1, the time for the start signal φS to be high is shortened and power consumption is reduced. Can be suppressed.

  The time between the time t2 and the time t3 is selected to be about 1/10 of the time when the first scanning signal φ1 becomes high level. In this way, the drive means 273 applies the scanning signal φ so that the time when the scanning signal φ applied to the adjacent switch element T is at the high level overlaps, whereby the threshold voltage or threshold current of the adjacent switch element T is applied. Is reliably lowered, the scanning signal φ can be set to a high level, and optical scanning can be performed reliably.

  In the present embodiment, the time during which the first and second scanning signals φ1 and φ2 are at the high level is selected to be about 1 μsec. Accordingly, the time between time t2 and time t3 is selected to be about 0.1 μsecond (μsecond).

  The light receiving portion Tr1 of the switch element T1 generates a trigger signal at the gate 228 of the light receiving portion Tr by light reception, and when the light emitting portion Ts1 of the switch element T1 is turned on at time t2, the first scanning signal φ1 that is set to the high level. The on state is maintained until becomes low level. When turned on, the voltage of the gate 224 of the switch element T1 becomes approximately 0 (zero) volts (V). Here, the voltage of the gate 224 of the switch element T1 is a potential difference between the gate 224 and the back electrode 236 to be grounded. Since the gate 224 of the switch element T1 is connected to the gate 219 of the light emitting element L1, the voltage of the gate 224 of the switch element T1 becomes equal to the voltage of the gate 219 of the light emitting element L1. Thus, the switch element T1 can change the voltage applied to the gate 219 and the back electrode 236 of the light emitting element L1.

  When the light emitting element L1 emits light, the driving unit 273 changes the light emission signal φE from the low level to the high level at time t4 after the time t3 has elapsed.

In the light emitting element L1, since the light emitting portion Ts1 of the switch element T1 is in the on state, the gate 219 of the light emitting element L1 is approximately 0 (zero) volts (V) as described above. At this time, the switch elements T2,..., Tj-1, Tj are in the off state, and the threshold voltage of the light emitting element L1 at time t4 is V _TH (L1), and the light emitting elements L2,. , Li is set to V _TH (L2),..., V _TH (Li-1), V _TH (Li), respectively, the high level V _H of the light emission signal φE is more than the threshold voltage of the light emitting element L1. The threshold voltage of the light emitting elements L2,..., Li-1, Li is selected to be smaller than the lowest value, so that only the light emitting element L1 can be selectively turned on to emit light. it can.

  At time t5, when the driving unit 273 sets the light emission signal φE to a low level, the light emitting element L1 is turned off and turned off. The exposure amount to the photosensitive drum is adjusted by the light emission time of the light emitting element L while the light emission intensity of the light emitting element L is constant. That is, the exposure amount is determined by determining the time between time t4 and time t5 when the light emission signal φE becomes high level. When changing the exposure amount according to the light emission intensity of the light emitting element L, it is difficult to finely control the voltage or current applied to the light emitting element L. However, by changing the exposure amount according to the light emission time, the light emission signal φE is changed. Since it is only necessary to adjust the high level time, it is easy to control the exposure amount, and a constant voltage or constant current is applied to the light emitting element L, so that the light emitting element L can stably emit light. The time during which the light emitting element L emits light, in other words, the time during which the light emission signal φE is at the high level, is selected to be 80% or less of the time during which the scanning signal φ is at the high level.

  After the time t5 has elapsed, when the driving unit 273 sets the second scanning signal φ2 to the high level at the time t6, the light emitting unit Ts2 of the switch element T2 emits light, and after the time t6 has elapsed, the first tapping occurs at the time t7. When the scanning signal φ1 is set to the low level, the light emitting portion Ts1 of the switch element T1 is turned off. As a result, the light emission state shifts from the switch element T1 to the switch element T2.

  After the time t7 has elapsed, when the driving unit 273 sets the first scanning signal φ1 to the high level at the time t8, the light emitting unit Ts3 of the switch element T3 emits light, and after the time t8 has elapsed, at the time t9, the second second When the scanning signal φ2 is set to the low level, the light emitting portion Ts2 of the switch element T2 is turned off. As a result, the light emission state is shifted from the switch element T2 to the switch element T3.

  After the time t9 has elapsed, when the driving unit 273 sets the second scanning signal φ2 to the high level again at the time t10, the light emitting unit Ts4 of the switch element T4 emits light, and after the time t10 has elapsed, at the time t11, When the one scanning signal φ1 is set to the low level, the light emitting portion Ts3 of the switch element T3 is turned off.

  The time between the time t6 and the time t7 is selected to be about 1/10 of the time when the second scanning signal φ2 becomes high level.

  As described above, the driving unit 273 repeatedly applies the first scanning signals φ1 and φ2, so that the ON state is sequentially transferred along the arrangement direction X also in the switch elements T4,..., Tj−1, Tj. When the light emitting portion Ts of the switch element T emits light, the light emission signal φE of the light emission signal transmission path 12 is changed from low level to high level, thereby corresponding to the light emitting switch element T, that is, emitting light. Only the light emitting element L connected to the switch element T having the light emitting portion Ts can be selectively caused to emit light.

FIG. 21 is a waveform diagram showing changes in the threshold voltage of the switch elements T1, T3, T5 connected to the first scanning signal transmission path 215a. In FIG. 21, the horizontal axis represents time, and represents the elapsed time from the reference time. In the figure, a start signal φS and first and second scanning signals φ1 and φ2 are also shown. Times t1, t2, t7, t8, and t11 shown in the figure correspond to the times t1, t2, t7, t8, and t11 shown in FIG. The initial threshold voltage of the switch elements T1, T3, T5 and V _BO, the threshold voltage lowered by the light receiving from the adjacent switch element T and V _1.

Since the scanning start switch element T0 emits light at time t1, the threshold voltage of the light emitting part Ts1 of the switch element T1 gradually increases when the light receiving part Tr1 of the switch element T1 receives the light of the scanning start switch element T0. reduced, the threshold voltage of the light-emitting portion Ts1 of the switching elements T1 at time ta will _{V 1.} Until the time t2 at which the light-emitting state of the scan start switch element T0 is maintained, threshold voltage of the switching element T1 is maintained at V _1.

At time t2, by the first scan signal φ1 changes from low level to high level, and the light-emitting switch element T1 is the threshold voltage of the switching element T1 is further at time tb decreases, the V _2. At time tb, the threshold voltage of the switching element T3, T5 _is a _{V BO.}

In time t7, the when the first scan signal φ1 changes from high level to low level, the threshold voltage of the switching element T1 is with time, gradually rises from V _2, also the light emitting portion Ts2 of the switching element T2 , The threshold voltage of the light emitting part Ts3 of the switch element T3 gradually decreases from V _{BO with} the passage of time, and at time tc, the threshold voltage of the light emitting part Ts3 of the switch element T3 is V ₁

At time t8, the threshold voltage of the light-emitting portion Ts3 of the switching element T3 is _{V 1,} the threshold voltage of the switch element T1 is a lower _{V 3} than higher _{V BO} than _{V 1,} the switching elements T5 The threshold voltage is V _BO .

At time t8, the first scanning signal φ1 is changed from the low level to the high level. This high level voltage is applied from the adjacent light emitting element L among the switch elements T connected to the first scanning signal transmission path 215a. among the light-emitting element L which is not receiving light, by higher than the threshold voltage V ₃ of the light-emitting portion Ts1 of the most the threshold voltage low emitting element L1, emit only the light emitting portion Ts3 of the switching elements T3 Can be made. When the switch element T3 emits light, the threshold voltage further decreases and becomes V ₂ at time td.

In time t11, the when the first scan signal φ1 changes from high level to low level, the threshold voltage of the switching element T3 is with the passage of time, gradually rises from V _2.

FIG. 22 shows the forward voltage-current characteristics of the light emitting portion Ts of the switch element T, and the range of the high-level voltage V _H of the first and second scanning signals φ 1 and φ 2 supplied to each scanning signal transmission path 215. It is a graph which shows. In FIG. 22, the horizontal axis represents the anode voltage, and the vertical axis represents the anode current. As shown by the characteristic curve in the figure, the light emitting portion Ts of the switching element T has an S-shaped negative resistance similar to that of a general thyristor. As described above, the switch element T can reduce the threshold voltage or the threshold current of the light emitting unit Ts by irradiating the semiconductor layer constituting the light receiving unit Tr with light. Thus, as described above, the switching element T functions as a switch because it transits from the point b in the off state where the characteristic curve and the load line 72 intersect to the point a in the on state where the characteristic curve and the load line 72 intersect. To do.

The initial threshold voltage of the light emitting portion Ts of the switch element T is set to V _B0, and the threshold voltage of the light emitting portion Ts in the state where the threshold voltage is lowered is the lowest by irradiating the light receiving portion Tr of the switch element T with light. and V _1, of the switching elements T connected to the same scanning signal transmission path 215, the threshold voltage of the light-emitting portion Ts of the second-threshold voltage is low the switch element T and V _3. This V ₃ is a light emitting portion Ts of the switch element T in which the threshold voltage is slightly lowered by receiving light, or a switch that is being restored to the initial state at the time of turn-off, that is, once turned on. This is the threshold voltage of the light emitting portion Ts of the element T.

The first and second scan signals .phi.1, voltage V _H of the high level of φ2 is supplied to the scanning signal transmission path 215 connected to the light emitting portion Ts of the switching element T may range indicated by reference numeral P3 in Fig. 22, i.e. wherein is set higher than the voltage V _3. The voltage V _H is selected to be lower than the rated voltage of the switch element T. For example, when the voltage V _H is increased, the switching speed of the light emitting unit Ts of the switch element T from the off state to the on state can be increased, thereby speeding up the transition of the light emitting state in the light emitting unit Ts of the switch element T. Therefore, the optical scanning can be speeded up. For example, when operating with a clock signal of 1 megahertz (MHz) at 5 milliamperes (mA), the voltage V _H is selected to be about 10 V, and the resistance value of the resistance element Rφ is selected to be 1.6 kΩ. As the voltage of the scanning signal φ becomes higher, it is necessary to limit the current flowing into the light emitting portion Ts of the switch element T, so the resistance value of the resistance element Rφ needs to be increased. Therefore, the resistance value of the resistance element Rφ is determined in consideration of the time constant determined by the resistance value of the resistance element Rφ and the capacitance value of the optical switch element T when the speed of optical scanning needs to be further increased. Is done.

  In the present embodiment, since the high level voltage of the scanning signal φ is set as described above, the threshold voltage or threshold of the light emitting unit Ts when the light receiving unit Tr of the switch element T receives light and is photoexcited. Even when the current is only about 80% of the initial threshold voltage or the threshold current, the light emitting state can be transferred by the switch element T. Therefore, even if the light receiving portion Tr of the switch element T does not have high light receiving sensitivity, the light emitting state can be transferred. The light receiving portion Tr of the switch element T is formed of the same semiconductor material as the light emitting element L and has a similar structure. Since the light emitting element L is required to have high light emitting efficiency, if the light emitting element L is designed to increase the light emitting efficiency, the light receiving sensitivity at the light receiving portion Tr of the switch element T realized by the same configuration as the light emitting element L is lowered. End up. Conversely, if the switch element T is designed so as to increase the light receiving sensitivity of the light receiving portion Tr of the switch element T, the light emission efficiency of the light emitting element L realized by the same configuration as the switch element T is lowered. In the present invention, since the switch element T does not have to have high light receiving sensitivity, the degree of freedom in design for increasing the light emission efficiency of the light emitting element L is improved, and the light emitting element L can efficiently emit light with less power. Thus, power consumption of the light emitting device 210 can be reduced.

  FIG. 23 is a plan view schematically showing the configuration of the light emitter chip 275 that constitutes the light emitting device 210. 1 is a part surrounded by c1, c2, c3, c4, c5, and c6 in the same drawing. FIG. 26 shows a plane of the light-emitting chip 275 arranged with the light emitting direction of each light-emitting element L as a front side perpendicular to the paper surface. The light-emitting element L, the switch element T, the connection means 214, and the signal transmission path connection portion 276 is shown with diagonal lines for ease of illustration.

  The light emitter chip 275 includes a first light emitter chip portion 277, a second light emitter chip portion 278, and a signal transmission path connection portion 276. The first light emitter chip portion 277 is the portion shown in FIG. 14 described above and is a portion surrounded by c1, c2, c3, c4, c5 and c6. The second light emitting chip portion 278 has the same configuration as that of the first light emitting chip portion 277, and has a shape in which the first light emitting chip portion 277 is angularly displaced by 180 degrees around an axis extending in the Z direction perpendicular to the paper surface. Have The light emitting element arrays 211 of the first light emitter chip part 277 and the second light emitter chip part 278 are arranged linearly at the center in the width direction Y of the light emitter chip 275. Therefore, each switching element T of the light emitting chip 275 is divided and arranged on one side and the other side of the light emitting element array 211 in the arrangement direction X of each light emitting element L and the width direction Y perpendicular to the arrangement direction X. Yes. The light emitter chip 275 is obtained by displacing a part of the basic structure of the light emitting device 210 shown in FIG. 14 and a part of the basic structure 180 degrees around an axis extending in the Z direction perpendicular to the paper surface, It has a shape in which the light emitting element array 211 is linearly arranged.

  The switch element array 213 of the first light emitter chip portion 277 disposed on the other side in the width direction Y of the light emitting element array 211 is referred to as a first switch element array 213a and is disposed on one side in the width direction of the light emitting element array 211. The switch element array 213 of the second light emitter chip portion 278 disposed will be referred to as a second switch element array 213b. In the present embodiment, the number of switch elements T in the first and second switch element arrays 213a and 213b is selected to be equal. The first switch element array 213a extends from the other end portion 275b of the light emitting chip 275 in the arrangement direction X to the center portion 275c in the arrangement direction X. The second switch element array 213b extends from one end portion 275a of the light emitting chip 275 in the arrangement direction X to the center portion 275c in the arrangement direction X.

  The first scanning start switch element T0 is provided on one side in the arrangement direction X of the first switch element array 213a, and the second scanning start switch element T0 is provided on the other side in the arrangement direction X of the second switch element array 213b. In the first switch element array 213a, the switch elements T1, T2,..., Tj−1, Tj are arranged in this order from one end portion to the other end portion in the arrangement direction X. In the second switch element array 213b, the arrangement is arranged. T1, T2,..., Tj−1, Tj are arranged in this order from the other end in the direction X toward one end.

  The light emitter chip 275 has a substantially rectangular parallelepiped shape, and a signal transmission path connection portion 276 is provided on one surface portion 279 of the thickness direction Z.

  The light-emitting element array 211 in which the light-emitting element arrays 211 of the first and second light-emitting chip portions 277 and 278 are arranged is formed across the one end 275a and the other end 275b of the light-emitting chip 275 in the arrangement direction X. The The distance from one end of the light emitting chip 275 in the arrangement direction X to the light emitting element L at one end in the arrangement direction X, and the distance from the other end of the light emitting chip 275 in the arrangement direction X to the light emitting element L at the other end in the arrangement direction X Is selected to be the distance W32 and smaller than the distance W21 between the adjacent light emitting elements L, and is preferably selected to be about ½ of the distance W21.

  In the width direction Y, the distance W33 from the end of each of the first and second light emitter chip portions 277 and 278 opposite to the light emitting element L to one end of the light emitter chip 275 in the width direction Y is The insulating layer 217 and the light shielding layer 218 that cover the end of the switching element T opposite to the light emitting element L are selected.

  In areas 280A and 280B adjacent to each other along the arrangement direction X of the first and second switch element arrays 213a and 213b, signal transmission line connection portions 276 are provided along the first and second light emitting element arrays 211, respectively. The signal transmission path connection unit 276 is a part for connecting the scanning signal transmission path 215, the light emission signal transmission path 212, and the start signal transmission path 216 to a bonding wire that is a signal transmission path from the outside, and is used for wire bonding. It is a bonding pad.

  The signal transmission line connection portion 276 is formed of a conductive material such as a metal material or an alloy material, and specifically, gold (Au), an alloy of gold and germanium (AuGe), and an alloy of gold and zinc. (AuZn) or the like.

  The signal transmission line connection unit 276 includes first and second start signal transmission line connection units 281a and 281b, first and second scanning signal transmission line connection units 282a and 282b, and first and second light emission signal transmission line connections. Part 283a, 283b. The first and second start signal transmission line connection parts 281a and 281b, the first and second scanning signal transmission line connection parts 282a and 282b, and the first and second light emission signal transmission line connection parts 283a and 283b have a thickness. They are formed in a rectangular shape when viewed from one side in the direction Z, and are formed in the same size.

  In a region 280A adjacent to one X1 in the arrangement direction of the first switch element array 213a, a first start signal transmission line connection unit 281a, a first scanning signal transmission line connection unit 282a, and a second light emission signal transmission line connection unit 283b are provided. And are provided. A first start signal transmission path connection portion 281a is provided on one side X1 of the first switch element array 213 in the arrangement direction X from one end of the scan start switch element T0 in the arrangement direction X with a distance W34. A first scanning signal transmission line connection part 282a is provided in one arrangement direction X1 of the first start signal transmission line connection part 281a. The first scanning signal transmission line connection unit 282a includes first and second transmission line connection units 284a and 284b. The first start signal transmission line connection unit 281a and the first and second transmission line connection units 284a and 284b are provided with an interval in the arrangement direction X, and are provided at equal intervals.

  In the present embodiment, the first transmission line connection unit 284a and the second transmission line connection unit 284b are arranged in this order from one arrangement direction X1 to the other arrangement direction X2. The start signal transmission path 216 of the first light emitter chip portion 277 is connected to the first start signal transmission path connection portion 281a, and the first scanning signal transmission path 215a of the first light emitter chip portion 277 is connected to the first transmission path. The second scanning signal transmission line 215b of the first light emitter chip part 277 is connected to the second transmission line connection part 284b. By connecting in this way, the dispersion | variation in the length of the transmission line from each transmission line connection part 284a, 284b to the light emission part Ts of each switch element T can be suppressed.

  In addition, a second light emission signal transmission path connection portion 283b is provided at one end 275a of the light emitting chip 275 in the arrangement direction X on the one side in the arrangement direction X of the first scanning signal transmission path connection portion 282a. The second light emission signal transmission path connection portion 283b is connected to the light emission signal transmission path 212 of the second light emitter chip portion 278. The second light emission signal transmission path connection portion 283b is provided at a distance W35 from one end in the arrangement direction X of the light emitting chips 275. The distance W35 is selected to be greater than the distance W32.

  The first start signal transmission path connection unit 281a, the first scanning signal transmission path connection unit 282a, and the second light emission signal transmission path connection unit 283b are provided outside the region where the light emitting element L is provided. A distance W36 is provided in the width direction Y. The distance W36 is selected so that when the light emitting element L emits light, the light is blocked by the signal transmission path connecting portion 276, and the amount of light does not decrease.

  In a region 280B adjacent to the other X2 of the second switch element array 213 in the arrangement direction, a second start signal transmission line connection unit 281b, a second scanning signal transmission line connection unit 282b, and a first light emission signal transmission line connection unit 283a are provided. Are provided. A second start signal transmission line connection portion 281b is provided in the other arrangement direction X2 of the second switch element array 213 and spaced from the one end in the arrangement direction X of the scanning start switch elements T by a distance W34 in the arrangement direction X. A second scanning signal transmission line connection part 282b is provided in the other X2 of the second start signal transmission line connection part 281b in the arrangement direction. The second scanning signal transmission line connection unit 282b includes third and fourth transmission line connection units 285a and 285b. The second start signal transmission line connection part 282b and the third and fourth transmission line connection parts 285a and 285b are provided at intervals in the arrangement direction X. Here, they are provided at equal intervals.

  In the present embodiment, the fourth transmission line connection unit 285a and the fifth transmission line connection unit 285b are arranged in this order from the other arrangement direction X2 toward the arrangement direction one X1. The start signal transmission path 216 of the second light emitter chip portion 278 is connected to the second start signal transmission path connection portion 281b, and the first scanning signal transmission path 215a of the second light emitter chip portion 278 is connected to the fourth transmission path. The second scanning signal transmission line 215b of the second light emitter chip part 278 is connected to the fifth transmission line connection part 285b. By connecting in this way, the dispersion | variation in the length of the transmission line from each signal transmission line connection part 276 to the light emission part Ts of each switch element T can be suppressed.

  A first light emission signal transmission line connection part 283a is provided at the other end part 275b of the light emitting chip 275 in the arrangement direction X on the other side X2 of the second scanning signal transmission line connection part 282b. The first light emission signal transmission path connection portion 283 a is connected to the light emission signal transmission path 212 of the first light emitter chip portion 277. The first light emission signal transmission line connection portion 283a is provided at a distance W35 from the other end of the light emitting chip 275 in the arrangement direction.

  The second start signal transmission path connection unit 281b, the second scanning signal transmission path connection unit 282b, and the first light emission signal transmission path connection unit 283a are provided outside the region where the light emitting element L is provided. A distance W36 is provided in the width direction.

  In the regions 280A and 280B where the signal transmission path connection portion 276 is formed, the respective signal transmissions are the light emission signal transmission paths 212, the first and second scanning signal transmission paths 215a and 215b, and the start signal transmission paths 216. The paths are insulated from each other by an insulating film having electrical insulation properties. The signal transmission path connection portion 276 and each signal transmission path are connected through a through hole formed in the insulating film.

  As described above, each switch element array 213 of the light emitter chip 275 in the light emitting device 210 of the present embodiment has the light emitting element array 211 of the light emitting element array 211 in the arrangement direction X of the light emitting elements L and the width direction Y perpendicular to the arrangement direction X. Since the signal transmission path connecting portion 276 is provided along the light emitting element array 211 in the regions 280A and 280B which are arranged separately on one side and the other side and which are adjacent along the arrangement direction X of each switch element array 213. The end of the light emitting element array 211 in the arrangement direction X can be disposed at the end of the light emitter chip 275, and the signal transmission path connection portion is provided on one side and the other side of the light emitting element array 211 in the width direction Y. In the configuration in which 276 is provided, the size of the light emitting chip 275 in the direction perpendicular to the arrangement direction X can be reduced as much as possible.

  When the light emitting element array 211 is formed at one end in the width direction Y of the light emitting chip 275, when the light emitting chip 275 is cut out from the wafer, the shape of the long side portion that is the arrangement direction X of the light emitting elements L is emitted. In order to prevent damage to the element L, it is necessary to add a process such as dicing precisely so as not to cause chipping or lapping after cutting. In the present embodiment, since the light emitting element array 211 is formed at the central portion in the width direction Y of the light emitting chip 275, the light emitting element L is not easily damaged when cut out from the wafer, so that dicing is easy. In addition, the yield can be improved and the manufacturing process is not increased.

  FIG. 24 is a partial plan view showing a basic configuration of a light emitter chip assembly 286 having a plurality of light emitter chips 275. This figure shows a plane of the light-emitting chip assembly 286 arranged with the light emitting direction of each light-emitting element L as the front side perpendicular to the paper surface. The light-emitting element array 211, the first and second switch element arrays 213a. , 213b and the signal transmission line connection portion 276 are indicated by hatching for easy illustration.

  The light emitter chip assembly 286 includes a plurality of light emitter chips 275 shown in FIG. 23, and is configured by linearly arranging the light emitting elements L of the light emitter chips 275. The light emitter chip assembly 286 is mounted by arranging the light emitting elements L of the light emitter chips 275 in a straight line with the back electrode 236 of the light emitter chip 275 facing a circuit board such as a printed wiring board.

  In the plurality of light emitter chips 275, since the light emitting elements L are arranged at the one end 275a and the other end 275b in the arrangement direction X, when the light emitting element array 211 is arranged along the arrangement direction X, adjacent light emitters are arranged. The light emitting elements L at the ends in the arrangement direction X of the chips 275 can be made as close as possible, and even if the light emitting chips 275 are arranged in a line, the distance W37 between the light emitting elements L of the adjacent light emitting chips 275 is set. Since it can be within the predetermined range, it is not necessary to arrange the light emitter chips 275 in a staggered manner, and the process of arranging the light emitter chips 75 on the circuit board can be simplified. The distance W37 is selected to be about the interval W21. The distance W37 is the same as the distance W12.

  Further, when the light emitting chips 275 are arranged and used as an exposure apparatus of the image forming apparatus, the light emitting elements L of the respective light emitting chips 275 can be arranged in a line, so that the exposure to the photosensitive drum via the lens array is possible. Then, the optical axis shift does not occur for each light emitting chip 275. As a result, the exposure characteristics of the plurality of light emitting chips 275 to the photosensitive drum can be made uniform, so that the image quality of the formed image can be improved. Furthermore, when the photosensitive drum is exposed, the plurality of light emitting chips 275 only need to read the data of the same line along the arrangement direction, and thus a memory function for storing the plurality of line data in the light emitting device 210 is necessary. In addition, the configuration of the apparatus can be simplified.

  The light emitting chip assembly 286 is used in an exposure apparatus as a line head such as an optical printer head for an electrophotographic image forming apparatus. The width W38 of the light emitting chip assembly 286 in the arrangement direction X is determined by the width of the image formed in the image forming apparatus 287.

  The signal transmission path connection portion 276 of each light emitting chip 275 is electrically connected to a portion to be connected to the circuit board by a bonding wire that is an external signal transmission path. The driving means 273 described above is mounted on the circuit board. The drive means 273 gives a signal to each signal transmission line connection part 276 via a bonding wire. By providing the driving means 273 on the circuit board on which the light emitting chip 275 is mounted, the distance of the signal transmission path from the driving means 273 to each light emitting element L, each switch element T, and the scanning start switch element T0 is shortened. Thus, it is possible to suppress noise from being superimposed on the signal transmitted through the signal transmission path from the driving unit 273 to the signal transmission path connection unit 276.

  The light emitting device 210 of the present invention can be used as an exposure device instead of the light emitting device 10 in the image forming apparatus 87 described above. In the image forming apparatus having such a configuration, bias light and leakage light are not generated from the light-emitting device 210 used as the exposure apparatus, so that a high-quality image can be formed. Further, since the light emitting device 210 in which the switch element T and the light emitting element L by the light emitting thyristor are integrated is used for the exposure apparatus, such an exposure apparatus can be manufactured at low cost, and thereby the manufacturing cost of the image forming apparatus. Can be reduced.

  As described above, in the light emitting device 210, when the light emitting part Ts of the switch element T emits light, the light of the light emitting part Ts is irradiated to the switch element T adjacent to the arrangement direction X of the switch elements T having the emitted light emitting part Ts. Is done. Since the light receiving portion Tr of each switch element T blocks light coming from the light emitting portion Ts included in the same switch element T, it is adjacent to one side and the other side in the arrangement direction of the switch element T having the emitted light emitting portion Ts. There is a clear difference in the amount of light applied to the switch element T.

  In the light receiving portion Tr facing the light emitting portion Ts of the switch element T adjacent to the other side in the arrangement direction X of the switch elements T having the emitted light emitting portion Ts, a trigger signal is generated at the gate 228 by light reception, and this trigger signal is Via the connection portion Tc, this trigger signal is given to the gate 227 of the light emitting portion Ts of the switch element T having the light receiving portion Tr that has generated the trigger signal. When a trigger signal is given to the gate 227, the threshold voltage or threshold current of the light emitting unit Ts decreases.

  In the switch element T adjacent to one side in the arrangement direction X of the switch element T having the emitted light emitting part Ts, the light emitted from the light emitting part Ts is transmitted by the light receiving part Tr of the switch element T having the emitted light emitting part Ts. Since the light is shielded, the amount of light to be irradiated becomes small, and the threshold voltage or threshold current of the light emitting portion Ts hardly decreases even if it is adjacent to the switch element T having the light emitting portion Ts that has emitted light.

  When the scanning signal φ transmitted through the scanning signal transmission path 215 to which the light emitting unit Ts is connected is given to the light emitting unit Ts whose threshold voltage or threshold current has decreased, the light emitting unit Ts emits light. Since the first and second scanning signals φ1 and φ2 transmitted by the first and second scanning signal transmission paths 215a and 215b are given at different timings for each switch element T adjacent in the arrangement direction X, adjacent switches When the light receiving portion Tr of the element T receives light, a scanning signal can be given to the switch element T having the light emitting portion Ts in which the threshold voltage or the threshold current has been lowered, and thereby the light emitting portion Ts of the switch element T is changed. Light can be emitted sequentially from one side to the other side in the arrangement direction X, optical scanning can be performed from one side to the other side in the arrangement direction X, and the switch elements T arranged in sequence can be switched in order.

  Even if the light emitting portions Ts of the switch elements T adjacent to the one side and the other side in the arrangement direction X of the switch elements T having the light emitting portions Ts emitting light are connected to the same scanning signal transmission path 215, as described above. In addition, the threshold voltage or threshold current of the light emitting part Ts of the switch element T adjacent to the other side in the arrangement direction X of the switch element T having the light emitting part Ts that emits light is switched to the switch adjacent to one side in the arrangement direction. Since the threshold voltage or the threshold current of the light emitting portion Ts of the element T can be greatly reduced, the switch element T having the light emitting portion Ts emitting light thereby is adjacent to one side and the other side in the arrangement direction X. Even if the same scanning signal is given to the light emitting part Ts of the switch element T to be activated, only the light emitting part Ts of the switch element T adjacent to the other side in the arrangement direction X is caused to selectively emit light. It is possible. As a result, the number of scanning signal transmission paths 215 can be reduced as much as possible. Even when only two scanning signal transmission paths 215 are provided as in the present embodiment, from one to the other in the arrangement direction X, Optical scanning is possible. When the light emitting portion Ts of each switch element T emits light, a trigger signal is generated at the gate 228 of the light receiving portion Tr of the switch element T adjacent in the arrangement direction X, and each switch element T along the arrangement direction X by optical scanning. Can generate trigger signals in sequence.

  Each switch element T receives light emitted from the light emitting part Ts of the adjacent switch element T by the light receiving part Tr, thereby reducing the light emitting part Ts threshold voltage or threshold current connected by the connecting part Tc. It is not necessary to connect a load resistor or the like connected between the diode for specifying the transfer direction and the power supply to the gate 224 of each switch element T. Therefore, the light emitting device 210 can be configured with as few signal transmission paths as possible without complicating the structure of the device. Compared with the configuration of the switch element array in the light emitting device 1 shown in FIG. 26 described above as the prior art, the structure of the device is simplified, so that the manufacturing process can be reduced and the productivity of the device can be reduced. Can be improved.

  Accordingly, only a predetermined light-emitting element L among a plurality of light-emitting elements L arranged can be selectively caused to emit light with as few signal transmission paths as possible without complicating the structure of the light-emitting device 210.

  Further, the light emitting device 210 can be easily manufactured by realizing the switch element T, the light emitting element L, and the start switch element T0 with a simple configuration in which P-type semiconductors and N-type semiconductors are alternately stacked. . The switch element T, the light emitting element L, and the start switch element T0 can be formed on the substrate 231 by the same manufacturing process, and the manufacturing process of the light emitting device 210 can be reduced as much as possible.

  Furthermore, since the switch element T, the light emitting element L, and the start switch element T0 are integrated on the same substrate 231, each element can be formed with high density. In the switch element array 13, the arrangement direction X Switch elements T adjacent to each other can be brought into close contact with each other. Accordingly, each switch element T can efficiently receive light from the adjacent switch element T, and is adjacent to the emitted switch element T even when the light emission intensity of the adjacent switch element T is small. The threshold voltage or threshold current of the switch element T can be reduced. Therefore, it is possible to reduce the power required for causing the switch element T to emit light, and to realize the light emitting device 210 with lower power consumption. Also in the light emitting element L, since the light emitting elements L adjacent in the arrangement direction can be brought into close contact with each other, the resolution of an image can be improved by using the image forming apparatus.

  Since each switch element T emits light in order along the arrangement direction X, the light emitting element L emits light by shielding this light by the light shielding layer 218 so as not to interfere with the light emitted by the light emitting element L. In this case, the light quantity of the light emitting element L is prevented from being reduced or increased, and a stable light quantity can be obtained. In addition, since the light shielding layer 218 prevents the bias light from leaking, the image forming apparatus using the light emitting device 210 can form an image with good quality without degrading the image quality.

  The insulating layer 217 is provided between each light emitting element L and each switch element T and each scanning signal transmission path 215 and light emission signal transmission path 212, and each light emitting element L and each switching element T and each scanning signal transmission path 212. 215 and the light emission signal transmission path 212 are prevented from being short-circuited.

  Further, in the light emitting device 210, the threshold voltage or threshold current when light from the adjacent switch element T is received is the threshold voltage or threshold current when light from the adjacent switch element T is not received. Therefore, the switch element T whose threshold voltage or threshold current is reduced by light reception can be selectively emitted, so that even if the switch element T does not have high light receiving sensitivity, The switch elements T can be made to emit light in order along the arrangement direction. Therefore, the light emission state of the switch element T can be sequentially shifted along the arrangement direction of the switch elements T without being influenced by the light receiving sensitivity of the switch element T, and the reliability of optical scanning is improved.

  FIG. 25 is a circuit diagram showing a partial equivalent circuit showing the basic configuration of the light emitting device 410 according to the third embodiment of the present invention. In the light emitting device 410 according to another embodiment of the present invention, the light emitting element L and the switch element T are not electrically connected by the connecting means 14 in the light emitting device 10 according to the first embodiment described above. And having an optically connected configuration. Since the other configuration is the same as that of the light emitting device 10, the same reference numeral is given to the same configuration, and the description thereof is omitted. In the light emitting device 410, the switching element T corresponding to the light emitting element L is arranged facing the light emitting element L in the width direction Y, and the light emitting element L corresponding to the light emitting element L when the switch element T emits light is disposed from the switch element T. The light emitting element L and the switch element T are arranged so that light is irradiated. Since the light emitting element L has the same structure as the switch element T and is composed of the same semiconductor material, the threshold voltage or the threshold current can be reduced by receiving light. Therefore, by causing the switch elements T to emit light in order in the arrangement direction and irradiating light to the light-emitting elements L corresponding to the switch elements T, the threshold voltage of each light-emitting element L or The threshold current can be decreased sequentially along the arrangement direction, and the light emitting element L can be selectively caused to emit light by applying the light emission signal φE described above. Therefore, even with such a configuration, the same effect as the light emitting device 10 can be achieved.

Furthermore, in another embodiment of the present invention, in the light emitting device of each of the above embodiments, the light emitting element L and the switch element T are the same as the light emitting thyristor L and the switch in the light emitting device 1 shown in FIG. You may connect so that thyristor T may be connected. That is, the gates 26 and 226 of the scanning start switch element T0 are connected to the start signal transmission paths 16 and 216, and the gates 24 and 224 of each switch element T and the gates 26 and 226 of the scanning start switch element T0 are connected to the load resistance. Two scanning signal transmission lines φ are arranged on the surface electrodes 25 and 225 of the switch element T and the scan start switch element T0 and connected to the control power source V _GK via R _L. Every other scan start switch element T0 is connected. The gates 24 and 224 of the switch element T and the gates 26 and 226 of the scan start switch element T0 are connected via a transfer direction designating diode D, and the gates 24 and 224 of the switch element Tn and the switch element Tn−1 are connected. The gates 24 and 224 are connected via a transfer direction designating diode D, and the gates 24 and 224 of the adjacent switch element T and the gates 26 and 226 of the scan start switch element T0 are connected via the transfer direction designating diode D. Connected. The transfer direction designation diode D has an anode connected to the gates 24 and 224 of the switch element T on the downstream side in the scanning direction. The anode of the light emitting element L is connected to the light emission signal transmission paths 12 and 212, and the cathode is grounded. Even if it is such a structure, the same effect can be achieved.

  In still another embodiment of the present invention, in the light emitting device of each embodiment described above, between the substrates 31 and 231 and the first one-conductivity type semiconductor layers 32 and 232 of the light emitting element L, the substrates 31 and 231 are provided. Between the substrates 31 and 231 and the first one-conductivity-type semiconductor layers 62 and 262 of the scan start switch element T0. Alternatively, a buffer layer made of one conductivity type semiconductor may be provided. With such a configuration, a semiconductor layer with improved crystallinity can be formed on the substrates 31 and 231 and the characteristics of the light emitting element L, the switch element T, and the scan start switch element T0 can be made more uniform. can do.

  By making the sheet resistance of the buffer layer or the first one-conductivity-type semiconductor layers 42 and 242 smaller than that of the second one-conductivity-type semiconductor layers 44 and 242, the direction perpendicular to the substrates 31 and 231 of the switch element T Can be concentrated in the region where the surface electrodes 25 and 225 connected to the scanning signal transmission lines 15 and 215 exist, so that the light emission efficiency can be improved.

  In still another embodiment of the present invention, an insulating substrate or a semi-insulating substrate may be used as the substrates 31 and 231 in the light emitting device of each embodiment described above. The substrate is made of, for example, semi-insulating gallium arsenide (GaAs), gallium nitride (GaN), sapphire, or the like. In the case of using such a substrate, the back electrodes 36 and 236 described above are not formed on the other surface in the thickness direction Z of the substrates 31 and 231, and the first one-conductivity-type semiconductor layers 32 and 232 of the light emitting element L, Cathode electrodes are formed on the first one-conductivity-type semiconductor layers 42 and 242 of the switch element T and the first one-conductivity-type semiconductor layers 62 and 262 of the scan start switch element T0. Even if it is such a structure, the same effect can be achieved.

  In the light emitting device according to still another embodiment of the present invention, the light emitting signal transmission paths 12 and 212 and the light emitting element light shielding portions 23 and 223 may be integrally formed in the light emitting device according to each embodiment described above. In this case, the bottoms of the groove portions 23 and 223 in which the light emitting element light shielding portions 23 and 223 are formed are covered by a part of the insulating layers 17 and 17 so that the light emitting element light shielding portions 23 and 223 and the substrates 31 and 231 do not contact each other. By forming, the short circuit between the light emission signal transmission paths 12 and 212 and the substrates 31 and 231 is prevented. In the thickness direction Z, the light-emitting element light-shielding portions 23 and 223 are formed from the ohmic contact layers 37 and 237 to the second one-conductivity-type semiconductor layers 34 and 234 and the second other-conductivity-type semiconductor layers 35 and 235. If it is formed so as to extend to the substrates 31 and 231 side from the light emitting part, the same effect can be achieved.

  In still another embodiment of the present invention, in the light emitting device of each embodiment described above, the light emitting device is stacked on the ohmic contact layers 37 and 237 of the light emitting element L and functions as an anode terminal together with the light emitting signal transmission lines 12 and 212. A metal layer may be formed. With such a configuration, the electric field to each semiconductor layer of the light emitting element L can be made uniform, and the emission intensity of light emitted from the light emitting element L can be increased.

  In still another embodiment of the present invention, in the light emitting device of each of the embodiments described above, the light shielding layers 18 and 218 have a higher reflectance of light having a wavelength emitted by the switch element T and are higher than the insulating layers 17 and 217. You may form with a material with a low refractive index. For example, the insulating layers 17 and 217 are made of polyimide. Since the light is not absorbed but is reflected by the light shielding layers 18 and 218, the light from the switch element T interferes with the light emitted from the switch element T in the thickness direction one Z1. In addition to preventing the light, the amount of light incident on the adjacent switch element T is increased, so that the light receiving efficiency of the switch element T can be increased.

  In still another embodiment of the present invention, in the light emitting device of each of the embodiments described above, one conductivity type may be a P type and the other conductivity type may be an N type. On the other hand, even if the conductivity type is P type and the other conductivity type is N type, the polarity of the bias voltage is opposite to that when the one conductivity type is N type and the other conductivity type is P type. The same effect as that of the light emitting device of the form can be obtained.

  In still another embodiment of the present invention, in the light emitting device of each of the embodiments described above, the high level voltage or current of the light emission signal φE output from the driving means 73 and 273 is the light emission signal transmission path 12, 212. The threshold voltage or threshold current of the other light emitting elements L excluding the light emitting element L to which the trigger signal is given by the switch element T connected to the switch element T may be selected to be a voltage higher or higher than the lowest value. . The light emission signal transmission lines 12 and 212 are connected to the connection means 14 and 214 via the resistance element Rφ, and the light emission element L whose threshold voltage or threshold current has been lowered by the trigger signal is connected. When the light emission signal φE having a voltage or current higher than the minimum threshold voltage or threshold current of the other light emitting elements L connected to the light emission signal transmission lines 12 and 212 is applied to the light emission signal transmission lines 12 and 212. The light emission signal φE is given to the light emission signal transmission lines 12 and 212 via the resistance element Rφ, and the voltage divided by the resistance element Rφ is given to the light emission element L. A voltage divided by the resistance element Rφ is gradually applied to each light emitting element L, and a trigger signal is given among the plurality of light emitting elements L connected to the light emitting signal transmission paths 12 and 212. The voltage or current applied to the light emitting element L is the earliest greater than the threshold voltage or threshold current of the light emitting element L. Accordingly, only the light emitting element L with the lowest threshold voltage or threshold current emits light, and the other light emitting elements L do not emit light. For this reason, the light emission signal φE can be easily controlled by the driving means 73 and 273.

  In still another embodiment of the present invention, in the light emitting device of each embodiment described above, the high level of the scanning signal φ output from the driving means 73 and 273 receives light from the adjacent switch element T. Therefore, the threshold voltage of the other switch elements T connected to the scan signal transmission paths 15 and 215 is connected to the scan signal transmission paths 15 and 215 to which the switch elements T whose threshold voltage or threshold current is reduced are connected. A voltage or current higher than the average threshold current is selected. Connected to the scanning signal transmission lines 15 and 215 to which the switching element T whose threshold voltage or threshold current has been lowered by receiving light from the adjacent switching element T is connected. When a scanning signal φ having a voltage or current higher than the average value of the threshold voltage or threshold current of the other switching element T is applied, the scanning signal φ is sent to the scanning signal transmission lines 15 and 215 via the resistance element Rφ. And a voltage divided by the resistance element Rφ is applied to the switch element T. The voltage divided by the resistance element Rφ is gradually applied to each switch element T, and the adjacent switch among the plurality of switch elements T connected to the same scanning signal transmission path 15, 215. The voltage or current applied to the switch element T that has received the light from the element T is earliest greater than the threshold voltage or threshold current of the switch element T. Thereby, only the switch element T with the lowest threshold voltage or threshold current emits light, and the other switch elements T do not emit light.

  Since the high level of the scanning signal φ output from the driving means 73 and 273 is set to a voltage or current higher than the average value as described above, a higher voltage is applied to the switch element T whose threshold voltage or threshold current has decreased. Alternatively, a high current can be applied to shift to the on state, and the optical scanning speed can be improved.

  In still another embodiment of the present invention, in the light emitting device of each embodiment described above, the high level of the scanning signal φ output by the driving means 73 and 273 is connected to the scanning signal transmission lines 15 and 215. It may be selected higher than the threshold voltage or threshold current of all the switch elements T. Even with such a configuration, the same effect can be achieved, and the driving means 73 and 273 can change the high-level voltage or current of the scanning signal φ to the threshold voltage or threshold that the switching element T varies. Since it can be determined irrespective of the current, the driving means 73 and 273 can be easily designed.

  In still another embodiment of the present invention, in the light emitting device of each of the embodiments described above, the driving means 73 and 273 are not provided on the circuit board on which the light emitting chips 75 and 275 are mounted, but the image forming apparatus main body. It may be configured to be provided on a circuit board on which the control means 96 is provided. By providing the driving means 73 at a location different from the circuit board on which the light emitting chips 75 and 275 are provided, the circuit board on which the light emitting chips 75 and 275 are provided can be further reduced in size, and the periphery of the photosensitive drum 90 It becomes easy to arrange in.

  In still another embodiment of the present invention, a plurality of light emitting elements L may correspond to the switch element T in the light emitting device of each embodiment described above. That is, the gates 24 and 224 of one switch element T or the gates 28 and 228 of the light emitting portion Ts of one switch element T may be connected to the gates 19 and 219 of the plurality of light emitting elements L. With such a configuration, a plurality of light emitting elements L can emit light simultaneously.

  In still another embodiment of the present invention, each semiconductor layer may be formed in multiple layers in the light emitting device of each of the above embodiments. For example, the first one-conductivity-type semiconductor layer may be formed by laminating a plurality of one-conductivity-type semiconductor layers, and the first other-conductivity-type semiconductor layer is composed of a plurality of other-conductivity-type semiconductor layers. The second one-conductivity-type semiconductor layer may be formed by stacking a plurality of one-conductivity-type semiconductor layers, and the second other-conductivity-type semiconductor layer may be composed of the other-conductivity-type semiconductor layer. A plurality of semiconductor layers may be stacked.

  In addition, this invention is not limited to the above-mentioned form, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention.

It is a partial top view which shows the basic composition of the light-emitting device 10 of the 1st Embodiment of this invention. FIG. 2 is a partial cross-sectional view illustrating a basic configuration of the light-emitting device 10 as viewed from a cutting plane line A1-A1 in FIG. FIG. 2 is a partial cross-sectional view illustrating a basic configuration of the light-emitting device 10 as viewed from a section line A2-A2 in FIG. 1. FIG. 2 is a partial cross-sectional view illustrating a basic configuration of the light-emitting device 10 as viewed from a section line A3-A3 in FIG. FIG. 2 is a partial cross-sectional view illustrating a basic configuration of the light-emitting device 10 as viewed from a section line A4-A4 in FIG. 1. It is a graph which shows the forward voltage-current characteristic which is the relationship of the anode voltage and anode current of the light emitting element L, the switch element T, and the scanning start switch element T0. It is a circuit diagram which shows a part of equivalent circuit which shows the basic composition of the light-emitting device 10 shown by FIG. The drive means 73 supplies the start signal φS to the start signal transmission path 16, the first scanning signal φ1 to be applied to the first scanning signal transmission path 15a, the second scanning signal φ2 to be applied to the second scanning signal transmission path 15b, and the third scanning signal. Waveforms indicating the third scanning signal φ3 applied to the transmission line 15 and the light emission signal φE applied to the light emission signal transmission path 12, the light emission intensity of the light emitting element L1, and the light emission intensity of the scanning start switch element T0 and the switch elements T1 to T4. FIG. It is a wave form diagram showing the change of the threshold voltage of switch element T1, T4, T7 connected to the 1st scanning signal transmission line 15a. 3 is a graph showing forward voltage-current characteristics of a switch element T and a range of a high-level voltage V _H of first to third scanning signals φ1 to φ3 supplied to each scanning signal transmission line 15. It is a top view which shows the structure of the light-emitting body chip | tip 75 which comprises the light-emitting device 10 of FIG. 4 is a partial plan view showing a basic configuration of a light emitter chip assembly 86 having a plurality of light emitter chips 75. FIG. 2 is a side view showing a basic configuration of an image forming apparatus 87 having a light emitting device 10. FIG. It is a partial top view which shows the basic composition of the light-emitting device 210 provided with the optical scanning device 209 of the 2nd Embodiment of this invention. FIG. 15 is a partial cross-sectional view illustrating a basic configuration of the light-emitting device 210 as viewed from a section line B1-B1 in FIG. FIG. 15 is a partial cross-sectional view illustrating a basic configuration of the light-emitting device 210 as viewed from a section line B2-B2 in FIG. 14. FIG. 15 is a partial cross-sectional view illustrating a basic configuration of the light-emitting device 210 as viewed from a section line B3-B3 in FIG. FIG. 15 is a partial cross-sectional view illustrating a basic configuration of the light-emitting device 210 as viewed from a section line B4-B4 in FIG. FIG. 15 is a circuit diagram illustrating a partial equivalent circuit illustrating a basic configuration of the light emitting device 210 illustrated in FIG. 14. The drive means 273 supplies the start signal φS to the start signal transmission path 216, the first scanning signal φ1 to be applied to the first scanning signal transmission path 215a, the second scanning signal φ2 to be applied to the second scanning signal transmission path 15b, and the light emission signal transmission. It is a wave form diagram which shows the light emission signal (phi) E given to the path | route 212, the light emission intensity of the light emitting element L1, and the light emission intensity of the scanning start switch element T0 and switch elements T1-T4.

It is a wave form diagram showing the change of the threshold voltage of switch element T1, T3, T5 connected to the 1st scanning signal transmission line 215a. 6 is a graph showing the forward voltage-current characteristics of the light emitting section Ts of the switch element T and the range of the high level voltage V _H of the first and second scanning signals φ 1 and φ 2 supplied to each scanning signal transmission line 15. is there. 3 is a plan view schematically showing a configuration of a light emitting chip 275 that constitutes the light emitting device 210. FIG. 4 is a partial plan view showing a basic configuration of a light emitter chip assembly 286 having a plurality of light emitter chips 275. FIG. It is a circuit diagram which shows a part of equivalent circuit which shows the basic composition of the light-emitting device 410 of the 3rd Embodiment of this invention. It is a circuit diagram which shows the schematic circuit structure of the basic structure of the prior art light-emitting device 1 which has a self-scanning function. FIG. 6 is a waveform diagram for explaining the operation of the light emitting device 1. 2 is a plan view of a light emitting chip 2 constituting the light emitting device 1. FIG. It is a top view which shows the arrangement | sequence state when using the several light-emitting device 1 as a linear light source.

Explanation of symbols

10, 210, 410 Light emitting device 11, 211 Light emitting element array 12, 212 Light emitting signal transmission path 13, 213 Switch element array 14, 214 Connection means 15, 215 Scan signal transmission path 16, 216 Start signal transmission path 17, 217 Insulating layer 18, 218 Light-shielding layer 75, 275 Light-emitting element chip L Light-emitting element T Switch element T0 Scan start switch element Ts Light-emitting part Tr Light-receiving part Tc Connection part

Claims (5)

A light-emitting element that has a plurality of light-emitting elements that emit light when a trigger signal is optically or electrically applied to a predetermined site and that emits a light-emitting signal, and the plurality of light-emitting elements are arranged at intervals. An array,
A light emission signal transmission path that is connected to each of the light emitting elements and transmits the light emission signal;
In response to the scanning signal, each of the corresponding light emitting elements has a plurality of switch elements that give a trigger signal to the predetermined portion, and each switch element is optically connected to the corresponding light emitting element in a state of facing the plurality of light emitting elements. or together are electrically connectable, the switch elements are arranged divided to one side and the other side of the light emitting element array in sequence direction of the light emitting elements, sites predetermined switching elements adjacent to each other A plurality of switch element arrays that are optically or electrically connected;
A plurality of scanning signal transmission paths that are connected to each switch element of the switch element array and transmit scanning signals given at different timings for each switch element adjacent in the arrangement direction;
Provided along the light emitting element array in a region adjacent to the arrangement direction of each switch element array, the light emitting signal transmission path and the external signal transmission path, and the scanning signal transmission path and the external signal transmission A signal transmission path connection section for individually connecting the paths,
A light-emitting device comprising: a light-emitting element light-shielding portion that is provided between the light-emitting elements and shields light from the light-emitting elements toward the arrangement direction.   The light emitting device according to claim 1, wherein the signal transmission path connection portion is a bonding pad.   3. The light emitting device according to claim 1, wherein the signal transmission path connection portion is formed at a predetermined distance from an end portion of the light emitting element array in a direction perpendicular to the arrangement direction.   A light-emitting device comprising a plurality of light-emitting devices according to claim 1, wherein each light-emitting element of each light-emitting device is arranged linearly. The light emitting device according to any one of claims 1 to 4,
Driving means for driving the light emitting device based on image information;
Condensing means for condensing the light from the light emitting element of the light emitting device on the charged photosensitive drum;
Developer supplying means for supplying developer to the photosensitive drum exposed by the light from the light emitting device being condensed on the photosensitive drum by the condensing means;
Transfer means for transferring an image formed by the developer supplied to the photosensitive drum by the developer supply means to a recording sheet;
An image forming apparatus comprising a fixing unit for fixing the developer transferred to the recording sheet by said transfer means.

Images