JP2007273627A - Light transfer array device and its manufacturing method, light-emitting device and device for forming image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light transfer array device capable of transferring a luminous state more surely between two adjacent light-emitting elements for light transfer and to provide a method for manufacturing the optical-transmission array device. <P>SOLUTION: The device 1 is configured including a plurality of switching elements T mutually arranged at intervals and a waveguide body 17 being fitted between the two adjacent switching elements T and introducing a light from one switching element T to the other switching element T in the two adjacent switching elements T. The surface 103 of the waveguide body 17 has a reflected-light condensing region 104, and the reflected-light condensing region 104 is formed in an outward projected curved-surface shape. When the light from one switching element T is reflected by the reflected-light condensing region 104, the device 1 is formed so that the light is projected to the other switching element T. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical transfer array device for transferring a light emission state and a method for manufacturing the same, a light emitting device including the optical transfer array device, and an image forming apparatus including the light emitting device.

  An electrophotographic image forming apparatus, for example, an electrophotographic printer, charges a photosensitive drum and exposes it to form an electrostatic latent image, develops it with a developer, forms a toner image, and transfers it to a recording sheet. Then, an image is formed by fixing. As a light emitting device used as a light source of an optical print head which is one of exposure apparatuses in an electrophotographic image forming apparatus, there is a light emitting device using a light emitting element array in which a plurality of light emitting elements are arranged in a row (for example, (See Patent Documents 1 and 2).

  As the light emitting element, for example, a light emitting thyristor which is a negative resistance element having a PNPN structure is used. In a light emitting device in which light emitting thyristors are arranged as a light emitting element array, light emission can be scanned by transferring a light emitting state. Patent Document 2 described above discloses a light-emitting device provided with a light-transmitting light-emitting element for transferring a light-emitting state separately from the light-emitting element. By using a light-transfer type light-emitting device that scans light emission by transferring a light-emitting state by a light-emitting element or a light-transmitting light-emitting element as an optical printer head, mounting on a substrate becomes simple and a light-emitting element array is made compact. be able to.

  In an optical transfer type light emitting device, an optical transfer array in which a light emitting element for transferring a light emission state or a light emitting element for optical transfer (hereinafter sometimes referred to as “light emitting element for optical transfer” in general) is arranged As a device, for example, a plurality of convex light emitting devices having a mesa structure are provided. These light emitting elements are arranged on the substrate with a space therebetween. In an optical transfer array device including an optical transfer array, an insulator is provided between two adjacent light transfer light emitting elements to electrically insulate the two light transfer light emitting elements. The insulator is made of a light-transmitting material and serves as a waveguide that guides light from one of the two adjacent light-transfer light-emitting elements to the other light-transfer light-emitting element. work. As a material of the insulator, for example, a polyimide resin is used (for example, see Patent Document 3).

JP 49-124992 A (2nd page, Fig. 3-4) Japanese Patent Laid-Open No. 9-92985 (page 5-6, FIG. 9) JP-A-6-338634 (page 2-3, FIG. 1)

  In the case of forming a waveguide which is an insulator with a curable resin such as a polyimide resin, for example, a curable resin material in which a precursor of a curable resin is dissolved or dispersed in a solvent is applied to the waveguide. After forming a curable resin layer by removing, the curable resin layer is cured. Since the curable resin material is applied so as to fill the recess formed by the two adjacent light-transmitting light-emitting elements, the surface opposite to the substrate in the thickness direction of the curable resin layer has a surface tension. It is dented to the substrate side by the influence. Moreover, since the curable resin layer shrinks by curing and the thickness thereof decreases, the surface of the curable resin layer is further recessed toward the substrate side. Therefore, in the conventional optical transfer array device, one surface in the thickness direction of the waveguide, which is the surface of the curable resin layer (hereinafter sometimes simply referred to as “surface”), for example, is shown in FIG. Like the waveguide 124 shown, it is formed in a concave curved surface shape recessed toward the substrate 31 side.

  When the surface of the waveguide has a concave curved surface, light incident on the adjacent light transfer light emitting element out of the light emitted from the light transfer light emitting element and reflected by the surface of the waveguide is guided. Since the surface of the body is smaller than when the surface of the body is flat, the waveguide loss is increased. In addition, in the surface of the waveguide near the light-emitting element for light transfer in the light emitting state, the incident angle θ ′ to the surface of the waveguide is smaller than when the surface of the waveguide is planar. . This increases the amount of light incident on the surface of the waveguide at an incident angle θ ′ that is smaller than the critical angle, which is the angle at which total reflection occurs where all of the incident light is reflected inside the waveguide. Since the amount of light that passes through the outside of the waveguide without being reflected inside is increased, the waveguide loss is increased. Therefore, compared to the case where the surface of the waveguide is planar, the amount of light guided to the adjacent light transfer light emitting element is reduced. Even if a voltage higher than the threshold voltage required in advance is applied or a current larger than the threshold current is supplied, the adjacent light transfer light emitting element does not emit light, and the light emission state is transferred to the adjacent light transfer light emitting element. There are cases where it cannot be done.

  If the light emitting state is not transferred in the optical transfer array device, the light emitting element that should emit light does not emit light in the case of the light emitting device that scans the light emitting state using the optical transfer array device. Therefore, in an image forming apparatus using such a light emitting device, a portion to be exposed of the photosensitive drum is not exposed, and an image defect, for example, a white spot in which a toner layer is not formed in a portion where a toner layer is to be formed occurs.

  An object of the present invention is to provide an optical transfer array device and a method for manufacturing the same, a light emitting device including the optical transfer array device, and a light emitting device that can more reliably transfer a light emitting state between two adjacent light transferring light emitting elements. An image forming apparatus including the apparatus is provided.

An optical transfer array device of the present invention includes a substrate,
A plurality of light-transfer light-emitting elements arranged on the substrate at intervals, each light-transfer light-emitting element being in a light receiving state for receiving light from the adjacent light-transfer light-emitting elements A light-emitting element array for light transfer whose threshold voltage or threshold current is smaller than the threshold voltage or threshold current in the non-light-receiving state;
A waveguide provided between two adjacent light transfer light-emitting elements, and guides light from one of the light transfer light-emitting elements to the other light transfer light-emitting element, The surface has a reflective condensing region, the reflective condensing region is formed in a convex curved shape that is convex outward, and light from the one light transfer light emitting element is reflected in the reflective condensing region. And a waveguide formed so as to be incident on the other light-transmitting light-emitting element when reflected.

Further, the optical transfer array device of the present invention is the above configuration, wherein each of the light transfer light-emitting elements has a light emitting unit and the light receiving unit,
The light emitting unit and the light receiving unit are provided by being stacked on the substrate in the order of the light receiving unit and the light emitting unit.

Further, the optical transfer array device of the present invention, in each of the configurations, each light-emitting element for optical transfer,
A first N-type semiconductor layer;
A first P-type semiconductor layer stacked on one surface portion in the thickness direction of the first N-type semiconductor layer;
A second N-type semiconductor layer stacked on one surface portion in the thickness direction of the first P-type semiconductor layer;
A light-emitting thyristor including a second P-type semiconductor layer stacked on one surface portion in the thickness direction of the second N-type semiconductor layer,
A cross section perpendicular to the stacking direction of the first P-type semiconductor layer or the second N-type semiconductor layer extends from the interface between the first P-type semiconductor layer and the second N-type semiconductor layer in the stacking direction. It is formed so that it decreases as it separates.

According to the method for manufacturing an optical transfer array device of the present invention, a threshold voltage or a threshold current is obtained when a plurality of light transfer light emitting elements are in a light receiving state for receiving light from adjacent light transfer light emitting elements. Array formation in which a plurality of light-transmitting light-emitting elements smaller than a threshold voltage or a threshold current in a non-light-receiving state are arranged on a substrate at a distance from each other to form a light-transmitting light-emitting element array Process,
A light-transmitting material containing a solid component containing a polybenzoxazole precursor and a solvent is filled between the light-emitting light-emitting elements and applied so as to cover each light-emitting light-emitting element, and the solvent is removed. A first light transmissive layer forming step of forming the first light transmissive layer by,
A step of forming a recess by partially removing a portion of the first light-transmitting layer that covers the light-emitting element for light transfer by exposing and developing the first light-transmitting layer;
A first curing step of curing the first light-transmitting layer;
The second light-transmitting layer is formed by applying the light-transmitting material so as to cover the first light-transmitting layer which is filled and hardened in the concave portion, and forming the second light-transmitting layer by removing the solvent. Process,
A second curing step of curing the second light transmitting layer.

  In the method for manufacturing an optical transfer array device according to the present invention, the translucent material has a solid content of 25 wt% or more and 80 wt% or less.

The light emitting device of the present invention is the light transfer array device, wherein each of the light transfer light emitting elements is larger than a threshold voltage or a threshold current when the light receiving element is in the light receiving state and is in the non light receiving state. Scanning signal transmission means for transmitting a scanning signal having a signal voltage or signal current smaller than a threshold voltage or threshold current, and each light-transmitting light-emitting element is in the light receiving state and when the scanning signal is applied An optical transfer array device for generating a trigger signal at a predetermined site in
A plurality of light emitting elements arranged at intervals from each other, and each of the light emitting elements is in a non-selected state when a threshold voltage or a threshold current is in a selected state where a trigger signal is given to a predetermined portion. Threshold voltage when the threshold voltage or threshold current is lower than the threshold voltage or threshold current when the threshold voltage or threshold current is greater than the threshold voltage or threshold current when the selected state is selected and when the selected state is not selected. Or a light emitting element array that emits light when a light emission signal having a signal voltage or a signal current smaller than a threshold current is given;
A light emission signal transmission means for transmitting the light emission signal to each of the light emitting elements;
And connecting means for connecting a predetermined portion of the light-emitting element and a predetermined portion of the light-transmitting light-emitting element.

The image forming apparatus of the present invention includes the light emitting device,
Driving means for driving the light emitting device based on image information;
Condensing means for condensing light from the light emitting element of the light emitting device on a charged photosensitive drum;
Developer supplying means for supplying the developer to the exposed photosensitive drum by which light from the light emitting device is condensed on the photosensitive drum by the condensing means;
Transfer means for transferring an image formed by the developer on the photosensitive drum to a recording sheet;
And fixing means for fixing the developer transferred to the recording sheet.

  According to the optical transfer array device of the present invention, when one light transfer light emitting element emits light among a plurality of light transfer light emitting elements provided at intervals on the substrate, this light transfer light emitting element emits light. The light from the light emitting element is guided by the waveguide and received by the adjacent light transmitting element for light transfer. Since the surface of the waveguide has a reflection condensing region, light from the light transfer light emitting element in the light emitting state is incident on the adjacent light transfer light emitting element when reflected by the reflection condensing region. Since the reflection condensing region is formed in a convex curved surface that is convex outward, the reflection condensing area that occupies the surface of the waveguide is larger than when it is formed in a concave curved surface and in a flat shape. The ratio of the light region can be increased. Further, in the reflection condensing region near the light transmitting light emitting element in the light emitting state, when the light from the light transmitting light emitting element in the light emitting state enters the reflective condensing region, the tangential plane method at the incident position is used. The incident angle, which is the angle formed by the line and the incident light beam, can be made larger than when the reflection condensing region is formed in a concave curved surface shape and in a planar shape. As a result, light from the light-transmitting light-emitting element in the light-emitting state easily enters the reflection / condensation region at an incident angle exceeding the critical angle, and total reflection is likely to occur. Of these, the waveguide loss can be reduced by increasing the ratio of the light reflected by the reflective condensing region. Therefore, of the light emitted from the light transfer light emitting element, the waveguide ratio, which is the ratio of the light guided to the adjacent light transfer light emitting element by the waveguide, can be increased.

  Since the waveguide has a high light guide rate, when the light transfer light emitting element emits light with the same light intensity, it is transferred to the light transfer light emitting element adjacent to the light transfer light emitting element. The amount of light can be increased, and the light transfer efficiency of the light transfer array device can be improved. Accordingly, the threshold voltage or threshold current of the light-transmitting light-emitting element that has received light can be more reliably reduced than the threshold voltage or threshold current in the non-light-receiving state. Therefore, the threshold voltage when the light transfer light emitting element adjacent to the light transfer light emitting element in the light emitting state is larger than the threshold voltage or threshold current in the light receiving state and in the non light receiving state or When a scanning signal having a signal voltage or a signal current smaller than the threshold current is applied, the threshold voltage or threshold current of the light transfer light emitting element adjacent to the light transfer light emitting element in the light emitting state is more reliably determined. In addition, the signal voltage or signal current of the scanning signal can be made smaller to emit light. For example, even if the light emission intensity of the light transfer light emitting element in the light emitting state slightly changes, when the scanning signal is given, the adjacent light transfer light emitting element can emit light more reliably. Also, the light emission state can be transferred reliably. Therefore, it is possible to improve the reliability of the transfer of the light emission state in the optical transfer array device.

  According to the optical transfer array device of the present invention, light from the light emitting part of the light transfer light emitting element is guided by the waveguide and received by the light receiving part of the adjacent light transfer light emitting element. Since the light-emitting part and the light-receiving part of the light-transmitting light-emitting element are provided on the substrate in the order of the light-receiving part and the light-emitting part, the reflection condensing region on the surface of the waveguide is in the stacking direction of the light-emitting part and the light-receiving part. It is formed in the part near the light emitting part. As a result, the light from the light emitting portion of the light transfer light emitting element can be reflected by the reflection condensing region and incident on the adjacent light transfer light emitting element. It is possible to increase the wave rate and transfer the light emission state more reliably. In addition, since the light-emitting part and the light-receiving part of the light-transmitting light-emitting element are provided by being stacked on the substrate, for example, compared to a case where the light-emitting part and the light-receiving part are provided side by side in a direction parallel to the waveguide direction, Can be miniaturized in the waveguide direction. Accordingly, it is possible to increase the integration density of the light transfer light emitting elements in the light transfer array, so that the degree of freedom in designing the light transfer array can be increased.

  Further, according to the optical transfer array device of the present invention, the light transfer light emitting element functions as a PNPN type light emitting thyristor. A “thyristor” includes a PNPN diode. When a forward voltage is applied to the light-emitting element for optical transfer, the junction between the first N-type semiconductor layer and the first P-type semiconductor layer, and the second N-type semiconductor layer and the second P-type semiconductor layer Light is generated from the joint part. When a forward voltage is applied to the light-emitting element for optical transfer, a stacked body of the first N-type semiconductor layer, the first P-type semiconductor layer, and the second N-type semiconductor layer, or the first P-type semiconductor. The stacked body of the layer, the second N-type semiconductor layer, and the second P-type semiconductor layer functions as a phototransistor.

  The cross section perpendicular to the stacking direction of the first P-type semiconductor layer or the second N-type semiconductor layer is separated from the interface between the first P-type semiconductor layer and the second N-type semiconductor layer in the stacking direction. It is formed so as to decrease with time. Therefore, the distance of the curve connecting one surface of the light transfer light emitting element in the stacking direction and the other surface along the side surface of the light transfer light emitting element is the same as the surface of the light transfer light emitting element stacked in the stacking direction. It becomes longer than the distance connected by a straight line parallel to the direction. Since the potential difference is a value obtained by integrating the electric field strength by the distance, the electric field strength becomes weaker as the distance becomes longer if the potential difference is the same. Therefore, the electric field strength in the stacking direction when a forward voltage is applied to the light-emitting element for light transfer is the strongest on the straight line connecting the shortest distances and the weakest in the side surface. As a result, the electric field strength in the stacking direction generated at the side surface of the light-emitting element for light transfer can be made smaller than the central portion in the direction perpendicular to the stacking direction.

  Since the side surface portion of the light-emitting element for light transfer has a discontinuous crystal structure, dangling bonds exist in the side surface portion, and surface levels are formed. When electrons are trapped in this surface level, the side surface portion of the light-transmitting light-emitting element is negatively charged, so that an inversion layer is formed on the side surface portion of the first P-type semiconductor layer. That is, the side surface portion of the light emitting element for light transfer does not function as a PNPN type light emitting thyristor. Since trapped electrons are present on the side surface of the light-emitting element for light transfer, the electrical resistance of the side surface is reduced. The side surface portion of the light-transmitting light-emitting element is in a state where current easily flows, but since the electric field strength in the stacking direction of the side surface portion can be reduced, generation of dark current flowing through the side surface portion can be suppressed. it can.

  The dark current acts as noise on the light incident on the portion functioning as the phototransistor, and the current due to the incident light hinders the function of lowering the threshold voltage of the light-transfer light emitting element. Since the generation of this dark current can be suppressed, the threshold voltage of the light-transfer light-emitting element can be efficiently lowered by the current generated by the incident light. Therefore, as the cross section perpendicular to the stacking direction of the first P-type semiconductor layer or the second N-type semiconductor layer moves away from the interface between the first P-type semiconductor layer and the second N-type semiconductor layer in the stacking direction. As compared with the case where the light transfer element is not formed to decrease, the light transfer light emitting element can be turned on by entering weak light, and the light receiving efficiency of the light transfer light emitting element can be improved.

  According to the method for manufacturing an optical transfer array device of the present invention, in the array formation step, the threshold voltage or threshold current when in the light receiving state is higher than the threshold voltage or threshold current when in the non-light receiving state. A plurality of small light-transmitting light-emitting elements are arranged on the substrate at a distance from each other to form a light-transfer light-emitting element array. In the first light-transmitting layer forming step, a light-transmitting material containing a solid component containing a polybenzoxazole precursor and a solvent is filled between the light-transmitting light-emitting elements and covers each light-transmitting light-emitting element. The first light transmitting layer is formed by applying and removing the solvent. The formed first light-transmitting layer is exposed and developed, whereby the portion of the first light-transmitting layer that covers the light-emitting element for light transfer is partially removed to form a recess. The 1st translucent layer in which the recessed part was formed is hardened | cured in a 1st hardening process. In the second translucent layer forming step, the translucent material is applied so as to cover the cured first translucent layer while filling the concave portion, and the solvent is removed to form the second translucent layer. . The formed second light transmitting layer is cured in the second curing step. A waveguide that guides light from one of the two adjacent light-transfer light emitting elements to the other light-transfer light-emitting element by the first light-transmitting layer and the second light-transmitting layer. It is formed.

  In the first light transmissive layer forming step, a light transmissive material containing a solid component containing a polybenzoxazole precursor and a solvent is used. For example, since the polybenzoxazole precursor is easily dissolved in γ-butyrolactone as a solvent, the content of the solid component containing the polybenzoxazole precursor can be increased by selecting such a solvent. Thereby, the unevenness | corrugation which arises in the 1st light transmission layer formed by removing a solvent can be made small. Further, since the first light transmissive layer is formed of a light transmissive material containing a polybenzoxazole precursor, for example, compared to a case where the first light transmissive layer is formed of a light transmissive material containing a benzocyclobutene compound, a recess forming step. The amount of elution from the inside of the first light-transmitting layer when developed in 1 can be reduced, and the amount of decrease in the thickness of the first light-transmitting layer formed between the light transfer light emitting elements can be reduced. As a result, the amount of dent on the substrate side of the first light-transmitting layer between the light-emitting elements for light transfer can be reduced.

  In the second light transmissive layer forming step, the light transmissive material is applied so as to cover the cured first light transmissive layer while filling the concave portion, and thus the second light transmissive layer formed by removing the solvent. The light layer is formed so as to be recessed toward the substrate in the recess of the first light transmitting layer. In addition, as described above, since the amount of depression of the first light-transmitting layer between the light-transmitting light-emitting elements toward the substrate side is small, inversion of the unevenness occurs in the second light-transmitting layer, and the light-transmitting light-emitting elements are formed between the light-transmitting light-emitting elements The portion covering the first light transmissive layer is formed in a shape that bulges in a direction away from the substrate than the portion formed in the concave portion of the first light transmissive layer. As a result, the surface of the waveguide formed by the first light-transmitting layer and the second light-transmitting layer is a reflective condensing region formed in a convex curved shape that protrudes outward, and is adjacent thereto. Of the two light transfer light emitting elements, a reflection light collection region is formed so that when light from one light transfer light emission element is reflected by the reflection light collection region, the other light transfer light emission element is incident on the other light transfer light emission device Is formed. Therefore, it is possible to obtain an optical transfer array device including a waveguide body having a reflection condensing region formed on a surface between two adjacent light-emitting elements for light transfer that are convex outwardly convex. .

  Further, according to the method for manufacturing an optical transfer array device of the present invention, since the translucent material having a solid component content including the polybenzoxazole precursor of 25 wt% to 80 wt% is used, the first transparent Unevenness generated in the optical layer can be more reliably reduced.

  According to the light emitting device of the present invention, the light emitting device is configured to include an optical transfer array device that has a higher light guide through the waveguide and higher light transfer efficiency than the conventional optical transfer array device. . When a scanning signal is applied when the light transfer light emitting element provided in the light transfer array of the light transfer array device is in a light receiving state, a trigger signal is generated at a predetermined portion of the light transfer light emitting element. Is applied to a predetermined portion of the corresponding light emitting element via the connecting means. When a trigger signal is given to a predetermined portion of the light emitting element and the light emitting element is selected, the threshold voltage or threshold current is lower than the threshold voltage or threshold current when the light emitting element is in the non-selected state. A signal voltage or signal current that is greater than the threshold voltage or threshold current in the selected state and smaller than the threshold voltage or threshold current in the non-light-receiving state for the light emitting element in the selected state. Each light emitting element can be selectively made to emit light by giving a light emission signal having Since the optical transfer array device that generates the trigger signal can emit the light-transmitting light emitting elements in order in the arrangement direction and transmit the trigger signal in order in the arrangement direction more reliably than in the conventional technique, Each light emitting element can be made to emit light more accurately and selectively than the above technique.

  According to the image forming apparatus of the present invention, the light emitting device is driven by the driving unit based on the image information, and the light from the light emitting device is condensed on the charged photosensitive drum by the light collecting unit. The body drum is exposed to form an electrostatic latent image on its surface. When the developer is supplied to the photosensitive drum on which the electrostatic latent image is formed by the developer supplying means, the toner in 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. Since the light-emitting device can selectively emit light from each light-emitting element more accurately than in the prior art, it is possible to obtain an excellent quality recorded image free from image defects such as white spots.

  FIG. 1 is a partial cross-sectional view showing a basic configuration of a light emitting device 10 according to an embodiment of the present invention. 2 and 3 are partial plan views showing the basic configuration of the light-emitting device 10. FIG. 1 is a cross-sectional view taken along the section line II in FIGS. 2 and 3. In FIG. 1, the switch element T shown in FIGS. 2 and 3 is shown by reducing the length W4 in the arrangement direction X. 2 and 3 show a 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. FIG. 3 is a plan view showing a state in which the light shielding layer 18 shown in FIG. 2 is removed. 2 and 3, the light emission signal transmission path 12, the light emitting element gate 19, the switch element gate 24, the scanning start switch element gate 26, the light emitting element light-shielding portion 23, and the ohmic contact layer 25 are easy to illustrate. In order to do so, it is shown with diagonal lines.

  The light-emitting device 10 includes a light-emitting element array 11, a light-emitting signal transmission path 12, a switch element array 13 that is a light-emitting element array for light transfer, connection means 14, and first to third scanning signal transmission paths 15a, 15b, 15c, a scanning start switch element T0, a start signal transmission line 16, a waveguide body 17, a light shielding layer 18, and a light emitting element light shielding portion 23. The optical transfer array device 1 is configured to include the switch element array 13, first to third scanning signal transmission paths 15 a, 15 b, 15 c, and driving means 73. The driving unit 73 may be provided outside the optical transfer array device 1.

  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, for example, a light emitting element for exposure used for exposure of the photosensitive drum 90 in the image forming apparatus 87 shown in FIG. 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 including 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. When the light emitting element L is in a selected state where a trigger signal is given to the gate 19 which is a predetermined portion, the threshold voltage when the light emitting element L is smaller than the threshold voltage when it is in a non-selected state or when it is in a selected state. The threshold current is smaller than the threshold current in the non-selected state.

  When the threshold voltage when the light emitting element L is in the selected state is smaller than the threshold voltage when it is in the non-selected state, the threshold voltage when the light emitting element L is in the selected state and in the selected state When a light emission signal φE having a signal voltage that is larger than the threshold voltage in the non-selected state and smaller than the threshold voltage is applied, the threshold voltage becomes smaller than the signal voltage of the light emission signal φE and light is emitted. When the threshold current when the light emitting element L is in the selected state is smaller than the threshold current when the light emitting element L is in the non-selected state, the threshold current when the light emitting element L is in the selected state and in the selected state When a light emission signal φE having a signal current larger than the threshold current in the non-selected state and smaller than the threshold current is given, the threshold current becomes smaller than the signal current of the light emission signal φE, and light is emitted.

  Thus, when the light emitting element L is in a selected state and the light emission signal φE is given, the threshold voltage becomes lower than the signal voltage of the light emission signal φE, or the threshold current is the signal of the light emission signal φE. It becomes smaller than the current and emits light. The “signal 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. The “signal current of the light emission signal φE” is a current given to the light emitting element L when the light emission signal φE is given.

  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. The For example, when the image resolution is 600 dot 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. Accordingly, it is possible to prevent 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 made of conductive wiring, for example, gold (Au), an alloy of gold and germanium (AuGe), an alloy of gold and zinc (AuZn), nickel (Ni) or It is formed of aluminum (Al).

  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 element connection part 22 which protrudes in the 3rd direction Y1 which is one direction of the width direction from existing part 21, and is connected to the thickness direction one end part of each light emitting element L. The light emission signal transmission path 12 corresponds to a light emission signal transmission means.

  The switch element array 13 is configured to include a plurality of switch elements T1, T2,..., Tj−1, Tj (symbol j is a positive integer of 2 or more), which are light-emitting elements for light transfer. Each of the switch elements T1, T2,..., Tj−1, Tj is arranged at an interval W3 so as to receive light from the adjacent switch elements T1, T2,. 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 T 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 light amount of the switch elements T from being insufficient.

  The switch element T is realized by including a light emitting thyristor 20 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 has a threshold voltage when receiving light from the adjacent switch element T, which is smaller than a threshold voltage when receiving light or not receiving light, or a threshold current when receiving light Is smaller than the threshold current in the non-light-receiving state.

  When the threshold voltage when the switch element T is in the light receiving state is smaller than the threshold voltage when the switch element T is in the non-light receiving state, the threshold voltage when the switch element T is in the light receiving state and in the light receiving state When the scanning signal φ having a signal voltage larger than that of the threshold voltage in the non-light-receiving state is applied via the scanning signal transmission line 15, the threshold voltage is higher than the signal voltage of the scanning signal φ. Becomes smaller and emits light, and a trigger signal is generated in the gate 24 which is a predetermined portion. When the threshold current when the switch element T is in the light receiving state is smaller than the threshold current when the switch element T is in the non-light receiving state, the threshold current when the switch element T is in the light receiving state and in the light receiving state When the scanning signal φ having a signal current larger than the threshold current in the non-light-receiving state is given, the threshold current becomes smaller than the signal current of the scanning signal φ and light is emitted. A trigger signal is generated in the gate 24 which is a predetermined portion.

  Thus, the switch element T is in the light receiving state and when the scanning signal φ is applied, the threshold voltage becomes smaller than the signal voltage of the scanning signal φ, or the threshold current is the signal of the scanning signal φ. When it becomes smaller than the current, light is emitted and a trigger signal is generated at the gate 24. The “signal 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. The “signal current of the scanning signal φ” is a current given to the switch element T when the scanning signal φ is given.

  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 to be at least twice the height h1 in the thickness direction Z of the switch elements T, but is preferably selected to be 25 μm or less, preferably It is selected to be 10 μm or less. In the present embodiment, the height h1 of the switch element T is about 4 μm, and in this case, the interval W3 is selected to be 22 μm, for example. If the interval W3 exceeds 25 μm, the optical transfer 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 Lk ₀ and the gate 24 of the switch element Tk ₀ . The symbol k ₀ is a natural number.

  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, for example, gold (Au), an alloy of gold and germanium (AuGe), an alloy of gold and zinc (AuZn), nickel (Ni), or aluminum (Al).

  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 corresponds to scanning signal transmission means. The scanning signal transmission line 15 is made of conductive wiring, for example, gold (Au), an alloy of gold and germanium (AuGe), an alloy of gold and zinc (AuZn), nickel (Ni), or aluminum (Al). Formed by.

  The first, second, and third scanning signal transmission paths 15a, 15b, and 15c are formed to overlap each switch element T via the insulating layer 17 in the fifth direction Z1, which is one of the thickness directions Z of each switch element T. , Extending along the arrangement direction X. 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 an ohmic contact layer 25 on the end in the fifth direction Z1 in the thickness direction Z, 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 ohmic contact layer 25 of each switch element T one by one, and each of the first, second, and third scan signal transmission paths 15a, 15b, and 15c is 3 along the arranged switch elements T. Every other one is connected to the switch element T. 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 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 one direction of the arrangement direction X of the switch elements Tn The switching element Tn-1 adjacent to the first direction X1 side and the switching element Tn + 1 adjacent to the second direction X2 side which is the other direction of the arrangement direction X of the switching elements Tn are different scanning signal transmission paths. 15 is connected.

  The scanning start switch element T0 is realized by the light emitting thyristor 20 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. In the scanning start switch element T0, like the light emitting element L, the threshold voltage when the trigger signal is applied to the gate 26 which is a predetermined portion is smaller than the threshold voltage when the trigger signal is in the non-selected state. Or the threshold current in the selected state is smaller than the threshold current in the non-selected state. The scanning start switch element T0 is in a selected state and is supplied with a scanning signal φ having a signal voltage that is larger than the threshold voltage in the selected state and smaller than the threshold voltage in the non-selected state. When the threshold voltage is lower than the signal voltage of the scanning signal, light is emitted. The scanning start switch element T0 is supplied with a scanning signal φ having a signal current larger than a threshold current in the selected state and smaller than a threshold current in the non-selected state. When this occurs, the threshold current becomes smaller than the signal current of the scanning signal φ and light is emitted.

  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. Accordingly, the first direction X1, which is one of the arrangement directions 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 line 16 is made of conductive wiring, for example, gold (Au), an alloy of gold and germanium (AuGe), an alloy of gold and zinc (AuZn), nickel (Ni) or It is formed of aluminum (Al).

  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 insulating layer 17 provided between the adjacent switch elements T and between the scanning start switch element T0 and the adjacent switch element T1 is a waveguide body 17. The waveguide body 17 which is the insulating layer 17 provided between the adjacent switch elements T guides light from the switch element T to the switch element T adjacent to the second direction X2 of the arrangement direction X which is the waveguide direction. The waveguide 17 which is the insulating layer 17 provided between the scanning start switch element T0 and the switching element T1 guides light from the scanning start switch element T0 to the switch element T1 adjacent in the waveguide direction.

  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. 3 of each switch element T. 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 portion 23 extends from the signal path extending portion 21 to the width direction between the light-emitting elements L and between the light-emitting elements L at both ends of the light-emitting element array 11 in the arrangement direction X. Is provided so as to protrude in the third direction Y1 and shields light from the light emitting element L toward the arrangement direction X.

  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. 4 is a partial cross-sectional view showing the basic configuration of the light emitting device 10 as seen from the section line IV-IV in FIG. 3. The light emitting element L includes a first N-type semiconductor layer 32, a first P-type semiconductor layer 33, a second N-type semiconductor layer 34, and a second N-type semiconductor layer 32 formed on one surface 31a in the thickness direction Z of the substrate 31. A P-type semiconductor layer 35 is included.

  In the present embodiment, the substrate 31 is made of an N-type semiconductor material. More specifically, the substrate 31 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. A back electrode layer 36 is formed on the other surface 31 b in the thickness direction Z of the substrate 31. The back electrode layer 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 layer 36 is formed of a conductive material such as a metal material and an alloy material. Specifically, the back electrode layer 36 is formed 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, the first N-type semiconductor layer 32 is stacked on the one surface 31 a in the thickness direction Z of the substrate 31, and the first N-type semiconductor layer 32 is formed on the one surface 32 a in the thickness direction Z. The P-type semiconductor layer 33 is stacked, the second N-type semiconductor layer 34 is stacked on the one surface 33 a of the first P-type semiconductor layer 33 in the thickness direction Z, and the thickness of the second N-type semiconductor layer 34 is A second P-type semiconductor layer 35 is stacked on one surface 34a in the direction Z.

The first N-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 N-type semiconductor layer 32 is desirably about 1 × 10 ¹⁸ cm ⁻³ .

The first P-type semiconductor layer 33 is formed of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs). The semiconductor material that forms the first P-type semiconductor layer 33 is the same as the energy gap of the semiconductor material that forms the first N-type semiconductor layer 32, or the semiconductor material that forms the first N-type semiconductor layer 32. Those having an energy gap smaller than the energy gap are selected. The carrier density of the first P-type semiconductor layer 33 is preferably about 1 × 10 ¹⁷ cm ⁻³ .

The second N-type semiconductor layer 34 is formed of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs). The semiconductor material that forms the second N-type semiconductor layer 34 is the same as the energy gap of the semiconductor material that forms the first P-type semiconductor layer 33 or the semiconductor material that forms the first P-type semiconductor layer 33. Those having an energy gap smaller than the energy gap are selected. The carrier density of the second N-type semiconductor layer 34 is the same as that of the first N-type semiconductor layer 32, the first P-type semiconductor layer 33, the second N-type semiconductor layer 34, and the second P-type semiconductor layer 35. It is desirable that it is the smallest of the layers and about 1 × 10 ¹⁶ cm ⁻³ to 1 × 10 ¹⁷ cm ⁻³ . The second N-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 P-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 P-type semiconductor layer 35 is the same as the energy gap of the semiconductor material forming the first P-type semiconductor layer 33 and the second N-type semiconductor layer 34, or the first P-type. A material having an energy gap larger than that of the semiconductor material forming the semiconductor layer 33 and the second N-type semiconductor layer 34 is selected. The carrier density of the second P-type semiconductor layer 35 is desirably about 1 × 10 ¹⁸ cm ⁻³ .

  The stacked body in which the first N-type semiconductor layer 32, the first P-type semiconductor layer 33, the second N-type semiconductor layer 34, and the second P-type semiconductor layer 35 are stacked has a substantially rectangular parallelepiped shape. The first N-type semiconductor layer 32, the first P-type semiconductor layer 33, the second N-type semiconductor layer 34, and the second P-type semiconductor layer 35 are covered with the insulating layer 17. The insulating layer 17 is formed of a resin material having electrical insulation and translucency, such as polybenzoxazole, polyimide, or benzocyclobutene resin. In this embodiment, since the insulating layer 17 is formed simultaneously with the insulating layer 17 as the waveguide 17 provided between the switch elements T as will be described later, it is formed of polybenzoxazole.

  A portion of the insulating layer 17 between the adjacent light emitting elements L has a V-shape in a virtual plane perpendicular to the width direction Y and is formed with a groove portion 38 close to one surface 31a of the substrate 31. The light-emitting element light-shielding part 23 is formed in the groove part 38. The light-emitting element light-shielding part 23 is formed along the surface of the groove part 38 and is provided from a side in the arrangement direction X of the second P-type semiconductor layer 35 to a position close to the one surface 31 a of the substrate 31. The light-emitting element light-shielding portion 23 is formed by the second N-type semiconductor layer 34 and the second P-type semiconductor layer 35 from at least one end portion in the thickness direction Z of the second N-type semiconductor layer 34 in the thickness direction Z. The light emitting portion is formed so as to extend to the substrate 31 side. The light-emitting element light-shielding part 23 and the substrate 31 are electrically insulated by the insulating layer 17. The light-emitting element light-shielding portion 23 is formed from the signal path extending portion 21 to one end portion in the width direction Y of the light-emitting element L, and is the first in the width direction of the light-emitting element L than the end portion in the width direction Y of the light-emitting element L. Extends in three directions Y1. 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.

  On the one surface 35a of the thickness direction Z of the second P-type semiconductor layer 35, the element connection portion 22 of the light emission signal transmission path 12 is connected. A through hole 39 is formed in a portion of the insulating layer 17 formed on the one surface 35 a of the second P-type semiconductor layer 35 in the thickness direction Z, and one of the element connection portions 22 is formed in the through hole 39. Part is formed, and the element connection part 22 is in contact with the second P-type semiconductor layer 35. 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 interface between the second N-type semiconductor layer 34 and the second P-type semiconductor layer 35 and in the region near the second N-type semiconductor layer 34.

  The length W6 in the arrangement direction X of the element connection portions 22 of the light emitting signal transmission path 12 is formed to be one third (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 is emitted from the light emitting element L by selecting the length W6 as described above, and in the fifth direction Z1, which is one of the thickness directions. Prevent as much as possible from blocking the light coming. Further, part of the light emitted from the light emitting element L and directed in the fifth direction Z1 and reflected by the light emitting signal transmission path 12 is reflected by the light emitting element light-shielding portion 23, the substrate 31, etc. Heading in the fifth direction Z1.

  As shown in FIG. 1 described above, the switch element T includes the back electrode layer 36, the substrate 31, and the light emitting thyristor 20 according to the embodiment of the present invention. The switch element T is configured by laminating the light emitting thyristor 20 on one surface 31 a of the substrate 31 in the thickness direction Z and laminating the back electrode layer 36 on the other surface 31 b of the substrate 31 in the thickness direction Z.

  The light-emitting thyristor 20 includes a first N-type semiconductor layer 42, a first P-type semiconductor layer 43, a second N-type semiconductor layer 44, a second P-type semiconductor layer 45, an ohmic contact layer 25, and the like. It is comprised including. In the light emitting thyristor 20, the first N-type semiconductor layer 42 is stacked on the one surface 31 a in the thickness direction Z of the substrate 31, and the first P-type is formed on the one surface 42 a in the thickness direction Z of the first N-type semiconductor layer 42. A semiconductor layer 43 is stacked, a second N-type semiconductor layer 44 is stacked on one surface 43 a of the first P-type semiconductor layer 43 in the thickness direction Z, and the second N-type semiconductor layer 44 has one thickness direction Z. A second P-type semiconductor layer 45 is laminated on the surface 44 a, and an ohmic contact layer 25 is laminated on one surface 45 a of the second P-type semiconductor layer 45 in the thickness direction Z. The stacking direction of the light emitting thyristors 20 is the same as the thickness direction Z.

  In the light emitting thyristor 20, the cross section perpendicular to the stacking direction of the second N-type semiconductor layer 44 is separated from the interface between the first P-type semiconductor layer 43 and the second N-type semiconductor layer 44 in the stacking direction. It is formed so as to decrease. The second N-type semiconductor layer 44 is assumed with a predetermined interval W7 from the interface between the first P-type semiconductor layer 43 and the second N-type semiconductor layer 44 in the fifth direction Z1, which is one of the thickness directions Z. The evacuation part 46 on the fifth direction Z1 side of the virtual one plane 40 parallel to the interface is formed, and the projection part 47 on the sixth direction Z2 side which is the other thickness direction of the virtual one plane 40. The retracting portion 46 is formed so as to retract inside the protruding portion 47 when viewed from the fifth direction Z1. In the present embodiment, the retracting portion 46 and the protruding portion 47 have a substantially rectangular parallelepiped shape. The distance W8 between the side surfaces in the first direction X1, which is one of the arrangement directions of the retracting portion 46 and the protruding portion 47, the distance W8 between the side surfaces in the second direction X2 that is the other direction in which the retracting portion 46 and the protruding portion 47 are arranged, The interval W8 between the side surfaces in the fourth direction Y2, which is the other in the width direction of 46 and the protrusion 47, is selected to be equal. Further, the interval W9 between the side surfaces in the third direction Y1, which is one of the width directions of the retracting portion 46 and the protruding portion 47 shown in FIG. 8 described later, is set wider than the interval W8 in order to form the connecting means 14 described later. .

  The first N-type semiconductor layer 42 and the first P-type semiconductor layer 43 have a substantially rectangular parallelepiped shape, and are formed so that each side surface is continuous with the side surface of the protruding portion 47. That is, the laminated body constituted by the first N-type semiconductor layer 42, the first P-type semiconductor layer 43, and the protrusion 47 has a substantially rectangular parallelepiped shape. The second P-type semiconductor layer 45 and the ohmic contact layer 25 have a substantially rectangular parallelepiped shape, and are formed so that each side surface is continuous with the side surface of the retracting portion 46. That is, the laminated body constituted by the retracting portion 46, the second P-type semiconductor layer 45, and the ohmic contact layer 25 has a substantially rectangular parallelepiped shape.

  The first N-type semiconductor layer 42, the first P-type semiconductor layer 43, the second N-type semiconductor layer 44, the second P-type semiconductor layer 45, and the ohmic contact layer 25 of the switch element T. It is preferable that the energy gap and the carrier density of the semiconductor material that constitutes are designed so as to increase the light receiving efficiency of the switch element T, the light extraction efficiency to the outside, and the light emission efficiency.

The first N-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 N-type semiconductor layer 42 is desirably about 1 × 10 ¹⁸ cm ⁻³ .

The first P-type semiconductor layer 43 is formed of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs). The semiconductor material that forms the first P-type semiconductor layer 43 is the same as the energy gap of the semiconductor material that forms the first N-type semiconductor layer 42 or the semiconductor material that forms the first N-type semiconductor layer 42. Those having an energy gap smaller than the energy gap are selected. The carrier density of the first P-type semiconductor layer 43 is desirably about 1 × 10 ¹⁷ cm ⁻³ .

The second N-type semiconductor layer 44 is formed of a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs). The semiconductor material that forms the second N-type semiconductor layer 44 is the same as the energy gap of the semiconductor material that forms the first P-type semiconductor layer 43, or the semiconductor material that forms the first P-type semiconductor layer 43. Those having an energy gap smaller than the energy gap are selected. The carrier density of the second N-type semiconductor layer 44 is such that the first N-type semiconductor layer 42, the first P-type semiconductor layer 43, the second N-type semiconductor layer 44, the second P-type semiconductor layer 45 and the ohmic contact. It is the smallest of all the contact layers 25, and is desirably about 1 × 10 ¹⁶ cm ⁻³ to 1 × 10 ¹⁷ cm ⁻³ . By forming the second N-type semiconductor layer 44 from a semiconductor material such as aluminum gallium arsenide (AlGaAs) and gallium arsenide (GaAs), high internal quantum efficiency can be obtained.

The second P-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 P-type semiconductor layer 45 is the same as the energy gap of the semiconductor material forming the first P-type semiconductor layer 43 and the second N-type semiconductor layer 44, or the first P-type. A material having an energy gap larger than that of the semiconductor material forming the semiconductor layer 43 and the second N-type semiconductor layer 44 is selected. The carrier density of the second P-type semiconductor layer 45 is desirably about 1 × 10 ¹⁸ cm ⁻³ .

The ohmic contact layer 25 is a P-type semiconductor layer in the present embodiment, and is for performing ohmic contact with the clock line 15 that is the scanning signal transmission path 15. By providing the ohmic contact layer 25, the ohmic property between the scanning signal transmission line 15 and the light emitting thyristor 20 can be improved. The ohmic contact layer 25 is formed of a semiconductor material such as gallium arsenide (GaAs) or indium gallium phosphide (InGaP). The carrier density of the ohmic contact layer 25 is desirably 1 × 10 ¹⁹ cm ⁻³ or more.

  The first N-type semiconductor layer 42 of the switch element T and the first N-type semiconductor layer 32 of the light emitting element L are formed of the same semiconductor material and have the same thickness. In addition, the first P-type semiconductor layer 43 of the switch element T and the first P-type semiconductor layer 33 of the light emitting element L are formed of the same semiconductor material and have the same thickness. In addition, the second N-type semiconductor layer 44 of the switch element T and the second N-type semiconductor layer 34 of the light emitting element L are formed of the same semiconductor material and have the same thickness. In addition, the second P-type semiconductor layer 45 of the switch element T and the second P-type semiconductor layer 35 of the light emitting element L are formed of the same semiconductor material and have the same thickness.

  The thickness of the first N-type semiconductor layer 42 of the switch element T is selected from 100 nm to 500 nm. The thickness of the first P-type semiconductor layer 43 of the switch element T is selected from 5 nm to 200 nm. Thus, by selecting the thickness of the first P-type semiconductor layer 43, a photo formed by the first N-type semiconductor layer 42, the first P-type semiconductor layer 43, and the second N-type semiconductor layer 34. The current amplification factor of the transistor portion is increased, and external light can be received efficiently. The thickness of the second N-type semiconductor layer 44 of the switch element T is selected from 500 nm to 1000 nm. The thickness of the second P-type semiconductor layer 45 of the switch element T is selected from 200 nm to 1000 nm. The thickness of the ohmic contact layer 25 of the switch element T is selected from 10 nm to 20 nm.

  The surface electrode layer 25 is formed of a conductive material such as a metal material and an alloy material. Specifically, the surface electrode layer 25 is formed of, for example, gold (Au), an alloy of gold and germanium (AuGe), or an alloy of gold and zinc (AuZn).

  The first N-type semiconductor layer 42, the first P-type semiconductor layer 43, the second N-type semiconductor layer 44, the second P-type semiconductor layer 45, and the ohmic contact layer 25 are covered with the insulating layer 17, It 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. Thus, the insulating layer 17 provided between two adjacent switch elements T functions as a waveguide 17 that guides light from one switch element T to the other 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.

  When a forward voltage equal to or higher than the threshold voltage is applied to the light emitting thyristor 20, the junction between the first N-type semiconductor layer 42 and the first P-type semiconductor layer 43, and the second N-type semiconductor layer 44 and the second Light is generated from the junction with the P-type semiconductor layer 45. Which junction is used to increase the intensity of light is selected by adjusting the layer thickness and impurity concentration of each layer. In the present embodiment, by adjusting the layer thickness and impurity concentration of each layer, as shown by the arrows in FIG. 1, in the vicinity of the interface between the second N-type semiconductor layer 44 and the second P-type semiconductor layer 45. The light is emitted mainly from the region near the second N-type semiconductor layer 44. A region near the second N-type semiconductor layer 44 near the interface between the second N-type semiconductor layer 44 and the second P-type semiconductor layer 45 corresponds to the light emitting unit 100. In addition, when a forward voltage is applied to the light emitting thyristor 20, the light receiving unit 101 that mainly receives light by the first N-type semiconductor layer 42, the first P-type semiconductor layer 43, and the second N-type semiconductor layer 44, in other words. A phototransistor portion is formed. Therefore, in the present embodiment, the light emitting unit 100 and the light receiving unit 101 are provided by being stacked in the fifth direction Z1, which is one direction of the thickness direction Z that is a direction perpendicular to the waveguide direction X2.

  FIG. 5 is an enlarged cross-sectional view showing a portion of the waveguide body 17 of the optical transfer array device 1 shown in FIG. In FIG. 5, the description of the light shielding layer 18 shown in FIG. 1 is omitted. In the present embodiment, the waveguide body 17 is formed so as to protrude toward the fifth direction Z1, which is a direction away from the substrate 31, and is opposite to the surface of the waveguide body 17, more specifically, the substrate 17 of the waveguide body 17. The first surface 103, which is the surface on the side, is formed in a convex curved shape that protrudes outward over the entire waveguide direction X2 between two adjacent switch elements T. As described above, in the present embodiment, the waveguide body 17 is formed such that an intermediate portion between both end portions in the waveguide direction X2 bulges out from both end portions between two adjacent switch elements T.

  The surface 103 of the waveguide body 17 has a portion that functions as the reflective condensing region 104. The reflection condensing region 104 is formed in a convex curved shape that is convex outward, more specifically, a convex curved shape that is convex toward the opposite side of the substrate 31. In the present embodiment, the light emitting unit 100 and the light receiving unit 101 of the switch element T are stacked on the substrate 31 in the order of the light receiving unit 101 and the light emitting unit 100, so It is formed in a portion near the light emitting unit 100 in the fifth direction Z1, which is the stacking direction.

  The reflection condensing region 104 is formed such that when the light 151 from the switch element T is reflected by the reflection condensing region 104, the light is incident on the switch element T adjacent to the switch element T in the waveguide direction X2. The Therefore, when the light 151 from the switch element T in the light emitting state is reflected by the reflection condensing region 104, it enters the adjacent switch element T. Since the reflection condensing region 104 is formed in a convex curved surface that is convex outward, the reflection condensing region 104 is formed on the surface 103 of the waveguide body 17 as compared with the case where it is formed in a concave curved surface and in the case of a flat surface. It is possible to increase the proportion of the portion that functions as the reflection condensing region 104.

  FIG. 6 is a cross-sectional view schematically showing the waveguide 124 in which the surface 124a is formed in a concave curved surface between the switch elements T. When the surface 124a of the waveguide 124 is formed in a concave curved surface shape, the light 153 incident on the surface 124a of the waveguide 124 in the portion near the light emitting side switch element T is reflected by the surface 124a of the waveguide 124. However, it is difficult for the light to enter the switch element T on the light receiving side. For example, part of the light from the light emitting side switch element T is reflected toward the substrate 31 by the surface 124 a of the waveguide 124, and does not enter the light receiving side switch element T. Therefore, when the surface 124a of the waveguide 124 has a concave curved surface shape, the reflected light of the surface 124a of the waveguide body 124 on the light receiving side is compared with the case where the surface 124a has a curved surface shape. The ratio of the region formed so as to be incident on the light beam, that is, the portion functioning as the reflection condensing region is small.

  In addition, when the surface of the waveguide is formed in a planar shape, the reflected light is incident on the light receiving side switch element T compared to the case where the waveguide is formed in a convex curved surface. Thus, the portion functioning as the reflection condensing region formed in such a manner becomes smaller.

  In the present embodiment, the surface 103 of the waveguide body 17 is formed in a convex curved surface shape, and the reflection condensing region 104 is formed in a convex curved surface shape. Compared with the case of being formed in a flat shape and the case of being formed in a planar shape, the region formed as the reflection condensing region 104 in the surface 103 of the waveguide body 17 can be enlarged. As a result, the amount of light incident on the light receiving side switch element T out of the light from the light emitting side switch element T can be increased, so that the waveguide loss can be reduced.

  Further, the light reflected by the portion near the light emitting side switch element T is reflected toward the substrate 31 side when the surface 124a of the waveguide 124 shown in FIG. In this embodiment, such light can also be reflected toward the light receiving side switch element T and incident on the light receiving side switch element T.

  Further, by forming the reflection condensing region 104 into a convex curved surface, the light 151 from the light emitting side switch element T is reflected in the reflection condensing region 104 near the light emitting side switch element T. The incident angle θ, which is the angle formed by the normal 150 of the tangential plane at the incident position and the incident light ray 151, is formed in the case where the reflection condensing region is formed in a concave curved surface shape and in the planar shape. It can be larger than the case.

  FIG. 7 is a cross-sectional view schematically showing the relationship between the shape of the surface of the waveguide and the incident angle. In FIG. 7, the case where the surface 103 of the waveguide 17 is formed in a convex curved surface is shown by a solid line, and the case where the surface of the waveguide is formed in a concave curved surface is shown by a two-dot chain line. A case where the surface is formed in a planar shape is indicated by a broken line. The incident angle θ when the light 151 emitted from the same position of the switch element T on the light emitting side is incident on the surface 103 of the waveguide 17 is formed so that the surface 103 of the waveguide 17 has a convex curved surface, and is reflected and condensed. The incident angle θa in the case where the region 104 is formed in a convex curved surface is larger than the incident angle θc in the case of the concave curved surface indicated by reference numeral 160, and in the case of the planar shape indicated by reference numeral 161. It becomes larger than the incident angle θb. By making the reflective condensing region 104 into a convex curved surface in this way, the light from the switch element T on the light emission side is compared to the case where the reflective condensing region is formed into a concave curved surface and a flat surface. The incident angle θ of light can be increased.

  Therefore, the light from the light-emitting side switching element T is easily incident on the reflection condensing region 104 at an incident angle θ exceeding the critical angle, and thus total reflection is easily caused. As a result, it is possible to increase the ratio of the light that is reflected by the reflective condensing region 104 out of the light incident on the reflective condensing region 104 and reduce the waveguide loss. For example, as shown in FIG. 6, when the surface 124a of the waveguide 124 is a concave curved surface, the light 154 transmitted through the waveguide 124 can be reflected by the reflection condensing region 104. Compared with the case where the surface 124 of the body 124 has a concave curved surface shape, the waveguide loss can be reduced.

  Thus, in this embodiment, the waveguide loss can be reduced, and the amount of light incident on the switch element T adjacent to the waveguide direction X2 out of the light from the light-emitting side switch element T can be increased. The light guide rate of the waveguide 17 can be increased. Therefore, when the switch element T emits light with the same light emission intensity, the amount of light transferred to the switch element T adjacent to the switch element T can be increased, so that the optical transfer efficiency of the optical transfer array device 1 can be increased. Can be improved.

  The reflection / condensation region 104 shown in FIG. 5 is formed so as to satisfy the following conditions (i) and (ii) at all points of the reflection / condensation region 104.

  (I) Outgoing surface of the light emitting side switch element T which is one light transmitting light emitting element provided on the upstream side in the waveguide direction X2 between the point P0 of the reflection condensing region 104 and two adjacent switch elements T A normal line Q0 of the reflected light condensing region 104 at the point P0 is included in a plane G connecting the one point P1 of the light receiving side and one point P2 of the light receiving surface of the light receiving side switch element T which is the other light transmitting light emitting element. It is.

  (Ii) an angle θ1 formed by a normal line Q0 at the point P0 and a straight line Q1 connecting the point P0 and the point P1 on the emission surface of the light emitting side switching element T; a normal line Q0 at the point P0; An angle θ2 formed by a straight line Q2 connecting the point P0 and the point P2 on the light receiving surface of the light receiving side switch element T is equal.

  When the condition (i) is not satisfied, that is, when the normal line Q0 at the point P0 is not on the plane G, the light reflected by the reflection condensing region 104 is widthwise from the light receiving surface of the light receiving side switch element T The light is incident on Y and is not incident on the light receiving surface.

  When the condition (ii) is not satisfied, that is, when the angle θ1 and the angle θ2 are not equal, the light reflected by the reflection condensing region 104 is shifted from the light receiving surface of the light receiving side switch element T in the thickness direction Z. Incident on the light-receiving surface.

  The reflection / condensation region 104 has a normal line Q0 at the point P0 and a straight line Q1 connecting the point P0 and the point P1 on the emission surface of the light emitting side switch element T at all points of the reflection / condensation region 104. The angle θ1 formed by is preferably formed to be larger than the critical angle. In this way, by forming the reflective condensing region 104 so that the angle θ1 formed by the normal line Q0 and the straight line Q1 at the point P0 is larger than the critical angle, total reflection is performed over the entire reflective condensing region 104. Can wake up. As a result, the amount of light reflected by the reflective condensing region 104 can be further increased, so that the light transfer efficiency can be further improved.

  The critical angle in the reflection condensing region 104 depends on the refractive index of the waveguide 17 and the refractive index of the layer in contact with the surface of the waveguide 17, for example, the refractive index of the light shielding layer 18 or the scanning signal transmission line 15. Therefore, the refractive index of the waveguide body 17 is such that all the points of the reflection condensing region 104 are a straight line Q1 passing through the normal line Q0 at the point P0 and the point P0 and the point P1 of the emission surface of the light emitting side switch element T. It is preferable that the angle θ1 formed by is selected so as to be larger than the critical angle.

  In the present embodiment, the height d2 of the first surface 103 of the waveguide 17 is set such that the interval W3 in the arrangement direction X between adjacent switch elements T, the height h1 of the switch elements T, and the light emitting unit 100 of the switch elements T and It is selected according to the position of the light receiving unit 101 and the like. The height d2 of the first surface 103 of the waveguide body 17 is preferably selected so that the proportion of the portion that functions as the reflective condensing region 104 in the first surface 103 is as large as possible. The “height d2 of the first surface 103 of the waveguide 17” is from the upper surface of the light emitting thyristor 20 that is the upper surface of the switch element T to the portion farthest from the substrate 31 of the first surface 103 of the waveguide 17. Is the distance. For example, when the interval W3 in the arrangement direction X between the switch elements T is 20 μm, the height d2 of the first surface 103 of the waveguide body 17 is selected to be greater than 0 μm and less than or equal to 5 μm. The height d2 of the first surface 103 of the waveguide body 17 is not limited to this, but is preferably greater than 0 μm and less than or equal to 5 μm when the interval W3 is 20 μm. When the height d2 of the first surface 103 of the waveguide body 17 exceeds 5 μm, the light emitted from the switch element T toward the first surface 103 of the waveguide body 17 and reflected by the first surface 103 is adjacent Therefore, the ratio of the reflective condensing region 104 is reduced, and the effect of improving the waveguide ratio is not sufficiently exhibited.

  Further, in the present embodiment, when viewed from the fifth direction Z1, which is one direction of the thickness direction, the protruding portion 47 is formed so that the peripheral portion protrudes from the retracting portion 46 over the entire circumference, so that the insulating layer of the light emitting thyristor 20 The distance of the curve connecting the one surface 20a and the other surface 20b in the thickness direction Z of the light-emitting thyristor 20 along the side surface in contact with 17 is the same as that in the thickness direction. It becomes longer than the shortest distance connecting with a straight line parallel to Z. Since the potential difference is a value obtained by integrating the electric field strength by the distance, the electric field strength becomes weaker as the distance becomes longer if the potential difference is the same. Therefore, the electric field strength in the thickness direction Z when a forward voltage is applied to the light emitting thyristor 20 is the strongest on the straight line connecting the shortest distances, and is the weakest on the side surface of the light emitting thyristor 20. Thereby, the electric field intensity in the thickness direction Z generated at the side surface portion of the light emitting thyristor 20 can be made smaller than that in the central portion in the direction perpendicular to the thickness direction Z.

  Since the crystal structure is discontinuous on the side surface in contact with the insulating layer 17 of the light-emitting thyristor 20, dangling bonds exist in the side surface portion, and a surface level is formed. When electrons are trapped in this surface state, the side surface portion of the light emitting thyristor 20 is negatively charged, so that an inversion layer is formed on the side surface portion of the first P-type semiconductor layer 43. That is, the side surface portion of the light emitting thyristor 20 does not function as the PNPN type light emitting thyristor 20. Since trapped electrons are present on the side surface of the light emitting thyristor 20, the electrical resistance of the side surface is reduced. The side surface portion of the light emitting thyristor 20 is in a state in which current easily flows, but since the electric field strength in the thickness direction Z of the side surface portion can be reduced, generation of dark current flowing through the side surface portion can be suppressed. . In particular, as seen from the fifth direction Z1, which is one of the thickness directions Z, the protruding portion 47 is formed so that the peripheral edge protrudes from the retracting portion 46 over the entire circumference, so that the generation of dark current is suppressed in all side surfaces. Can do.

  When light enters a depletion layer formed at the junction between the first P-type semiconductor layer 43 and the second N-type semiconductor layer 44, electrons and holes are caused to enter the light-emitting thyristor 20 according to the intensity of the incident light. A pair is generated and current flows. This current lowers the threshold voltage of the switch element T, but the generated holes are consumed by recombination with the carriers of the inversion layer, which is the source of the dark current, and the generated current is reduced. It wo n’t drop that much. That is, the dark current acts as noise on the incident light. Since the generation of this dark current can be suppressed, the threshold voltage of the light emitting thyristor 20 can be efficiently lowered by the current generated by the incident light. Therefore, the cross section perpendicular to the stacking direction Z1 of the second N-type semiconductor layer 44 decreases as the cross-section is separated from the interface between the first P-type semiconductor layer 43 and the second N-type semiconductor layer 44 in the stacking direction Z1. Compared with the case where the light emitting thyristor 20 is not formed, the light emitting thyristor 20 can be turned on by entering weak light, and the light receiving efficiency of the light emitting thyristor 20 can be improved.

  The thinner the gap W7, that is, the thickness of the protrusion 47, can suppress the generation of dark current more efficiently, and the light receiving efficiency of the light emitting thyristor 20 can be improved. The interval W7 is preferably selected to be ½ (½) or less of the thickness in the thickness direction Z of the second N-type semiconductor layer 44, for example, 0.5 μm or less.

  The intervals W8 and W9 are selected in a range in which the generation of dark current can be suppressed when a forward voltage is applied to the light emitting thyristor 20, for example, 1 μm or more. The upper limits of the interval W8 and the interval W9 are selected so that the intensity of light emitted from the light emitting thyristor 20 does not decrease excessively. For example, the dimension of the retracting portion 46 in the array direction X is The dimension is selected to be about one-half (1/2) of the dimension, and the dimension of the retracting portion 46 in the width direction Y is about one-half (1/2) of the dimension of the protruding portion 47 in the width direction Y. . The intervals W8 and W9 are preferably selected in a range where the light receiving efficiency is highest, and are selected to be 2 μm or more and less than 5 μm.

  Any one of the first to third scanning signal transmission lines 15a, 15b, and 15c is connected to one surface 25a of the ohmic contact layer 25 in the thickness direction Z. A through hole 49 is formed in a portion of the insulating layer 17 formed on the one surface 25 a of the ohmic contact layer 25 in the thickness direction Z. Any one of the first to third scanning signal transmission paths 15a, 15b, and 15c is connected through the through hole 49, and the switch element T and the first to third scanning signal transmission paths 15a, 15b, and 15c are connected. The other two scanning signal transmission lines 15 are electrically insulated by an insulating layer 17. 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 the fifth direction Z1 side which is one of the thickness directions of the switch element T. .

  In the present embodiment, in the switch element T, the connection portion of the scanning signal transmission line 15 with the ohmic contact layer 25 functions as an anode terminal, and the back electrode layer 36 functions as a cathode terminal. In the light emitting element L, the connection portion of the light emitting signal transmission path 12 with the second P-type semiconductor layer 35 functions as an anode terminal of the light emitting element L, and the back electrode layer 36 also functions as a cathode terminal of the light emitting element L. To do. 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.

  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. It is. 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.

  The light emitted from the switch element T and traveling in the fifth direction Z1 which is one of the thickness directions is the interface between the insulating layer 17 serving as the waveguide 17 and the scanning signal transmission path 15, the scanning signal transmission path 15, and the insulating layer 17. The light is reflected by an interface with the light shielding layer 18 or absorbed by the light shielding layer 18. Each scanning signal transmission line 15 and the insulating layer 17 form a reflecting means. This prevents light from the switch element T from interfering with light emitted from the light emitting element L in the fifth direction 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.

  Further, in the present embodiment, the surface 103 of the waveguide 17 has a reflection / condensation region 104, and the reflection / condensation region 104 is formed in a convex curved shape that is convex outward. As a result, of the light emitted from the switch element T, it is reflected at the interface between the reflection / condensing region 104 of the waveguide body 17 and the light shielding layer 18 and is incident on the switch element T adjacent to the waveguide direction X2. The amount can be increased. Therefore, the amount of light absorbed by the light shielding layer 18 can be reduced, and the light emitted from the switch element T can be used more effectively.

  FIG. 8 is a partial cross-sectional view showing the basic configuration of the light emitting device 10 as viewed from the section line VV in FIG. 3. The light emitting element L and the switch element T are arranged adjacent to each other in the width direction Y. The end of the light emitting element L near the switch element T of the first N-type semiconductor layer 32, the first P-type semiconductor layer 33, and the second N-type semiconductor layer 34 is the second P-type semiconductor layer. The light emitting element connection portion 51 is configured to protrude toward the switch element T from the end portion of the 35 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 N-type semiconductor layer 42, the first P-type semiconductor layer 43, and the second N-type semiconductor layer 44 is the second P-type. The end of the semiconductor layer 45 near the light emitting element L protrudes toward the switch element T, thereby forming the switch element connecting 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.

  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 separated by the insulating layer 17. Electrically 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 serving as a 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 in the thickness direction Z of the second N-type semiconductor layer 34, and the switch element connection portion 52. Through holes 55 are respectively formed in portions of the second N-type semiconductor layer 44 laminated on the one surface 44a in 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 54 and 55, the one surface 34 a in the thickness direction Z of the second N-type semiconductor layer 34 of the light emitting element connection portion 51, and the switch element connection. It is connected to one surface 44a of the thickness direction Z of the second N-type semiconductor layer 44 of the part 52. 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 may be attenuated, but the trigger signal is emitted from the switch element T by selecting the resistance value of the connecting means 14 within the above range. Attenuation when transmitted to the element L can be suppressed.

  The second N-type semiconductor layer 34 of the light-emitting element L is the gate 19 of the light-emitting element L, and the second N-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.

  An end portion of the second P-type semiconductor layer 35 of the light emitting element L near the switch element T is covered with the light emitting signal transmission path 12 described above 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 extension portion 21 of the light emission signal transmission path 12 is provided facing the side portion of the second P-type semiconductor layer 35 that faces the switch element T, and the second P-type semiconductor of the light-emitting element connection portion 51. Cover the end near the layer 35.

  Further, the end portion of the switch element T near the light emitting element L of the second P-type semiconductor layer 45 is 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. 9 is a partial cross-sectional view showing the basic configuration of the light emitting device 10 as seen from the section line VI-VI in FIG. 3. 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 N-type semiconductor layer 42 is stacked on the one surface 31a in the thickness direction Z of the substrate 31, and the first N-type semiconductor layer 42 on the one surface 42 in the thickness direction Z. The first P-type semiconductor layer 43 is stacked on the first P-type semiconductor layer 43, the second N-type semiconductor layer 44 is stacked on the one surface 43a in the thickness direction Z of the first P-type semiconductor layer 43, and the second N-type semiconductor layer is stacked. The second P-type semiconductor layer 45 is stacked on one surface 44 a of the thickness direction Z of 44, and the ohmic contact layer 25 is formed on the one surface 45 a of the thickness direction Z of the second P-type semiconductor layer 45. Is done.

  Further, the end portion of the scanning start switch element T0 near the light emitting element L of the first N-type semiconductor layer 42, the first P-type semiconductor layer 43, and the second N-type semiconductor layer 44 is the second N-type semiconductor layer 42. The P-type semiconductor layer 45 protrudes from the end of the P-type semiconductor layer 45 near the light emitting element L toward the light emitting element array 11 to 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 being laminated on the insulating layer 17 laminated in the fifth direction Z1, which is one of the thickness directions of the scanning start switch element T0, and the fifth of the scanning start switch elements T0 of the insulating layer 17 is formed. A part of the third scanning signal transmission path 15c is formed in the through hole 69 formed in the portion laminated in the direction Z1, and the third scanning signal transmission path 15c is connected to the scanning start switch element T0 via the through hole 69. To the ohmic contact layer 25. 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 N-type semiconductor layer 44 of the scan start switch element T0 is the gate 26 of the scan start switch element T0.

  The optical transfer array device 1 is manufactured by a method for manufacturing an optical transfer array device according to an embodiment of the present invention. FIG. 10 is a flowchart showing the procedure of the method for manufacturing the optical transfer array apparatus according to the embodiment of the present invention. FIG. 11 is a cross-sectional view schematically showing how the optical transfer array device 1 is manufactured. The manufacturing method of the optical transfer array device of the present embodiment includes an array formation process (step s1), a first transmission layer formation process (step s2), a recess formation process (step s3), and a first curing process (step s4). ), Second light transmitting layer forming step (step s5), through hole forming step (step s6), second curing step (step s7), transmission path forming step (step s8), and light shielding layer forming step. (Step s9).

  In the array formation step of step s1, as shown in FIG. 11A, the switch element array 13 is formed by arranging a plurality of switch elements T on the substrate 31 at intervals. The switch element T is formed simultaneously with the light emitting element L and the scan start switch element T0. More specifically, each light-emitting element L, each switch element T, and scan start switch element T0 are formed on the first surface 31a of the substrate 31 with the first N-type semiconductor layers 32 and 42 and the first P-type semiconductor layer 33. , 43, second N-type semiconductor layers 34, 44, second P-type semiconductor layers 35, 45, and ohmic contact layer 25 are formed by epitaxial growth and chemical vapor deposition (CVD) as semiconductor materials. After sequential lamination by a method or the like, patterning and etching are performed by photolithography. As described above, in this embodiment, the light emitting element L, the switch element T, and the scan start switch element T0 can be simultaneously formed in a series of manufacturing processes, so that the manufacturing cost can be reduced.

  In the first light transmissive layer forming step of step s2, the first light transmissive layer 110 to be the waveguide body 17 is formed. More specifically, first, a light-transmitting material for forming the first light-transmitting layer 110 is applied so as to fill the gaps between the switch elements T and cover the switch elements T, thereby forming the first coating layer 111. In the present embodiment, the translucent material is filled between the light emitting elements L and between the scanning start switch element T0 and the adjacent switch element T, and covers the light emitting element L and the scan start switch element T0. To be applied.

  As the light-transmitting material, a light-transmitting material containing a solid component containing a polybenzooxazole (abbreviated as PBO) precursor and a solvent is used. More specifically, a light-transmitting material having a positive type that changes soluble in a developer upon exposure or a negative type that changes insolubility to a developer upon exposure is used. Since polybenzoxazole precursors are easily soluble in lactones such as γ-butyrolactone or N-methyl-2-pyrrolidone, particularly in γ-butyrolactone, polybenzoxazole precursors can be selected by selecting such a substance as a solvent. The content rate of the solid component containing a body can be raised. In this embodiment, the content rate of the solid component containing a polybenzoxazole precursor is 25 wt% or more and 80 wt% or less, and more specifically 30 wt% or more and 40 wt% or less.

  The solid component contained in the translucent material includes a PBO precursor and a photosensitizer. Examples of the PBO precursor include a compound having an o-aminophenol structure and a benzoic acid structure in one molecule, such as 3-amino-4-hydroxybenzoic acid. Examples of the compound having an o-aminophenol structure and a benzoic acid structure in one molecule also include a polybenzoxazole precursor having a repeating unit represented by the following general formula (1).

In the general formula (1), R ¹ represents at least one group selected from the groups represented by the following general formula (2), R ² represents a divalent organic group, and m represents 2 to 1000. Indicates an integer.

In the general formula (2), R ³ represents a hydrogen atom, a trialkylsilyl group, or an active ester group or a carboxyl group represented by the following general formula (3). 1 to 4 R ³ may be attached to the same benzene ring. The hydrogen atom of the benzene ring contained in the group represented by the general formula (2) is at least one selected from an alkyl group, an aromatic ring group, an ether group, a hydroxyl group, a fluorine atom and a trifluoromethyl group. It may be substituted with a group.
-COOR ⁴ (3)

In the general formula (3), R ⁴ represents an alkyl group, a pyridyl group, a quinolyl group, an aromatic ring group or a benzotriazole group, and a hydrogen atom in these groups may be substituted with at least one organic group. . The hydrogen atom contained in the alkyl group, pyridyl group, quinolyl group, aromatic ring group and benzotriazole group may be substituted with at least one organic group.

Examples of the alkyl group denoted by R ⁴ in the general formula (3) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a t-butyl group, an isobutyl group, and a sec-butyl group. Examples thereof include an alkyl group having 1 to 4 carbon atoms. Examples of the pyridyl group include a 2-pyridyl group, a 3-pyridyl group, and a 4-pyridyl group. Examples of the quinolyl group include a 2-quinolyl group, a 3-quinolyl group, a 4-quinolyl group, a 5-quinolyl group, a 6-quinolyl group, a 7-quinolyl group, and an 8-quinolyl group. Examples of the aromatic ring group include a phenyl group, a 1-naphthyl group, and a 2-naphthyl group. Examples of the benzotriazole group include a 1-benzotriazole group.

Examples of the trialkylsilyl group represented by the symbol R ³ in the general formula (2) include a trimethylsilyl group.

Examples of the divalent organic group represented by the symbol R ² in the general formula (1) include a phenyl group, a biphenyl group, a naphthyl group, a diphenylsulfone group, a diphenyl ether group, a fluorenyl group, a phenylfluorenyl group, and a biphenylene group. Is mentioned. These groups may have a substituent such as an ethynyl group or a phenylethynyl group.

  The PBO precursor represented by the general formula (1) is disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-247997. Like the PBO precursor represented by the general formula (1), a PBO precursor having an o-aminophenol structure and a benzoic acid structure in one molecule includes, for example, an aromatic diamine compound and a dicarboxylic acid compound. It can be synthesized by a known acid chloride method, an activated ester method, or a dehydration condensation reaction in the presence of a dehydration condensation agent such as polyphosphoric acid or dicyclohexylcarbodiimide. Examples of the aromatic diamine compound include 3,5-diaminobenzoic acid (3-pyridyl) ester and 2,4-diaminoresorcinol. Examples of the dicarboxylic acid compound include 5- (3-pyridyloxycarbonyl) isophthalic acid and terephthalic acid. As the PBO precursor, a mixture of the aforementioned aromatic diamine compound and dicarboxylic acid compound may be used.

  The polybenzoxazole resin that forms the insulating layer 17 that is the waveguide 17 is obtained, for example, by dehydrating and ring-closing the PBO precursor by a condensation reaction or a crosslinking reaction. More specifically, the polybenzoxazole resin is a method in which the PBO precursor is heated at 150 ° C. to 240 ° C. for 5 minutes to 24 hours, a method in which the PBO precursor is irradiated with ultraviolet rays, and a method in which the PBO precursor is irradiated with an electron beam. Etc. The PBO precursor is cured by a dehydration ring-closing reaction by heating, for example, as shown in the following reaction formula (4), and becomes a polybenzoxazole resin.

  When the translucent material has positive photosensitivity, for example, a naphthoquinone diazide compound or a diazoquinone compound is used as the photosensitizer. As the PBO precursor, a photosensitive PBO precursor may be used. When the PBO precursor has photosensitivity, the solid component may not contain a photosensitizer. As the solvent for the translucent material, for example, lactones such as γ-butyrolactone, and organic solvents such as N-methyl-2-pyrrolidone are used.

  The translucent material is applied by, for example, a spin coater. The thickness S1 of the first coating layer 111 is selected to be about 1 to 1.5 times the height h1 of the switch element T from the first surface 31a of the substrate 31 (hereinafter sometimes simply referred to as “height”) h1. For example, it is about 3 to 5 μm.

  After forming the first coating layer 111 in this way, the solvent is removed from the first coating layer 111 by pre-baking the substrate 31 on which the first coating layer 111 is formed, for example, by heating to 180 ° C. Thus, the first light transmissive layer 110 is formed. The formed first light-transmitting layer 110 has a concave curved surface so that the first surface 110a, which is one surface in the thickness direction, is recessed toward the substrate 31 between two adjacent switch elements T.

  In the recessed portion forming step of step s3, a portion covering the switch element T in the formed first light transmitting layer 110 is partially removed to form the recessed portion 112. In the present embodiment, as shown in FIG. 11C, the portion of the first light transmitting layer 110 that covers the switch element T is removed so that the switch element T is exposed, and the through hole 112 is formed as the recess 112. The recess 112 is formed by patterning and etching by so-called photolithography, in which the formed first light transmitting layer 110 is exposed and developed with a developer. As the developer, for example, an aqueous alkaline developer containing alkali and water such as tetramethylammonium hydroxide (abbreviated as TMAH) is used.

  The width W10 of the recess 112 in the waveguide direction X2 is selected to be about 0.8 to 1.2 times the width W11 between the switch elements T at the uppermost part, which is the part farthest from the substrate 31 of the switch element T. It is about 11 μm to 20 μm. The depth h2 of the recess 112 in the stacking direction Z1 is selected to be about 0.5 μm to 2 μm.

  The recess 112 is formed not only in the portion covering the switch element T of the first light transmissive layer 110 but also in the portion covering the scan start switch element T0. In the recess forming step, the first light transmitting layer 110 is exposed so that the recess 112 is formed, and is exposed so as to obtain a target pattern of the insulating layer 17.

  In the first curing step of step s4, the first light transmissive layer 110 in which the recess 112 is formed is cured. When the PBO precursor which comprises the 1st light transmission layer 110 is thermosetting, the 1st light transmission layer 110 is hardened | cured by heating the board | substrate 31 with which the 1st light transmission layer 110 was formed, for example. When the PBO precursor is photocurable, the first light transmissive layer 110 can be cured by irradiating the first light transmissive layer 110 with light. In a state after being cured, the amount of depression of the first surface 110a of the first light transmissive layer 110 between the switch elements T, that is, the first surface 31a of the substrate 31 and the first surface 110a of the first light transmissive layer 110 is defined. A value d1 obtained by subtracting the minimum value of the distance between the first surface 31a of the substrate 31 and the first surface 110a of the first light transmitting layer 110 from the maximum value of the distance is, for example, 0.85 μm.

  In the second light transmissive layer forming step of step s5, the second light transmissive layer 113 to be the waveguide 17 is formed. More specifically, first, a translucent material for forming the second translucent layer 113 is applied so as to fill the recess 112 formed in the first translucent layer 110 and cover the first translucent layer 110, A second coating layer 114 is formed. As the translucent material, similar to the first translucent layer 110, the translucent material containing a solid component containing a PBO precursor and a solvent, and more specifically, containing a solid component containing a PBO precursor and a solvent. A translucent material in which the content of the solid component including the PBO precursor is 25% by weight or more and 80% by weight or less is used. The translucent material is applied by, for example, a spin coater. The thickness S2 of the second coating layer 114 is selected to be about 1 to 2 times the height h1 of the switch element T, for example, about 3 μm to 6 μm. The “thickness S2 of the second coating layer 114” is the thickness of the second coating layer 114 in the portion covering the first surface 20a in the thickness direction Z of the switch element T.

  Next, the solvent is removed from the second coating layer 114 by pre-baking the substrate 31 on which the second coating layer 114 is formed, for example, by heating to 180 ° C. Thereby, the second light transmissive layer 113 is formed. Inversion of the unevenness occurs in the second light transmitting layer 113, and the formed second light transmitting layer 113 has a first surface 113 a, which is the surface opposite to the substrate 31 in the thickness direction, of the first light transmitting layer 110. The portion formed in the recess 112 is recessed toward the substrate 31 side, and a convex curved surface projecting in a direction away from the substrate 31 in the portion covering the first light transmitting layer 110 formed between the switch elements T is formed.

  In the through hole forming process of step s6, the formed second light transmissive layer 114 is patterned and etched by photolithography so that the switch element T is exposed at a portion covering the switch element T in the second light transmissive layer 114. The through holes 115 are formed by partially removing the holes. The through hole 115 is used for connection between the switch element T and the scanning signal transmission path 15.

  In the recess forming step, the second light transmissive layer 113 is exposed so as to form the through hole 116 and is exposed so as to obtain a target pattern of the insulating layer 17. More specifically, the second light transmitting layer 113 includes the light emission signal transmission path 12, the connection means 14, the first to third scanning signal transmission paths 15a, 15b, and 15c, the start signal transmission path 16, and the light emission. The through holes 39, 49, 54, 55, 69, 71 necessary for connection to the element L, the switch element T, or the scan start switch element T0 are formed by patterning and etching by photolithography.

  In the second curing step of step s7, the second light transmissive layer 114 in which the through holes 115 are formed is cured in the same manner as the first light transmissive layer 110. As a result, the waveguide body 17 including the first light transmitting layer 110 and the second light transmitting layer 114 is formed. The formed waveguide body 17 has a convex curved surface shape in which a portion of the first surface 103 formed between the switch elements T protrudes away from the substrate 31. Therefore, according to the present embodiment, the waveguide body 17 having the convexly curved reflection condensing region 104 which is convex outward is formed on the surface 103. In the state after the second light transmissive layer 114 is cured, the protrusion amount d2 of the waveguide body 17 between the switch elements T is, for example, 0.66 μm. The “projection amount d2 of the waveguide body 17 between the switch elements T” is the height d2 of the surface 103 of the waveguide body 17 described above, and is the first of the waveguide bodies 17 formed between the switch elements T. This is the maximum value of the distance between the one surface 103 and the virtual plane 116 including the first surface 20a of the switch element T.

  In the transmission path forming step in step s8, a scanning signal transmission path is formed by laminating a conductive layer made of a conductive material on the surface of the cured second light transmitting layer 113 by vapor deposition or the like, and patterning and etching by photolithography. 15 is formed. The conductive layer is formed so as to fill the through hole 116 and other through holes. In the transmission path forming step, the light emission signal transmission path 12, the connection means 14, the first to third scanning signal transmission paths 15a, 15b, and 15c, the start signal transmission path 16, and the light emitting element light shielding portion 23 are simultaneously provided. It is formed. Therefore, the light emitting signal transmission path 12, the connecting means 14, the first to third scanning signal transmission paths 15a, 15b, and 15c, the start signal transmission path 16, and the light emitting element light-shielding portion 23 are formed to have substantially the same thickness. Is done. In the transmission path forming step, the back electrode layer 36 made of a conductive material is formed on the second surface 31b of the substrate 31 by vapor deposition or the like.

  In the light shielding layer forming step of step s9, for example, a light shielding material that becomes the light shielding layer 18 is applied onto the surface of the conductive layer that forms the scanning signal transmission path 15 and the like and the insulating layer 17 that is the exposed waveguide body 17 to form a photo. The light shielding layer 18 is formed by patterning and etching by lithography. In this way, the optical transfer array device 1 is manufactured. In the present embodiment, the light emitting device 10 including the optical transfer array device 1 is manufactured.

  In the present embodiment, the surface 104 of the waveguide body 17 can be formed in a convex curved surface shape. The translucent material contains a solid component containing a PBO precursor and a solvent, and contains a solid component containing a PBO precursor. The use of a translucent material having a rate of 25% by weight or more and 80% by weight or less is considered to contribute greatly. FIG. 12 is a cross-sectional view schematically showing how the waveguide body 17 is formed using a translucent material containing a PBO precursor. FIG. 13 is a cross-sectional view schematically showing how a waveguide is formed using a light-transmitting material containing a cyclobenzobutene (abbreviated as BCB) compound. FIG. 14 is a cross-sectional view schematically showing how a waveguide is formed using a translucent material containing a polyimide precursor. 12-14, the switch element T and the board | substrate 31 which are shown in FIG. 11 are shown integrally.

  Examples of the BCB compound include a BCB compound represented by the following structural formula (5). For example, as represented by the following reaction formula (6), the BCB compound is crosslinked and cured by repeating a Diels-Alder reaction by heating to become a BCB resin. Thus, the polar group is not involved in the curing reaction of the BCB compound, and no by-products such as water generated during the curing reaction of the PBO precursor are generated.

As the polyimide precursor, for example, polyamic acid (7c) obtained by reaction of diamine compound (7a) and acid anhydride (7b) is used as shown in the following reaction formula (7). The polyamic acid (7c) is imidized and cured by heating to become a polyimide resin (7d). In the curing reaction of the polyimide precursor, hydrogen atoms and hydroxyl groups in the portion surrounded by the dotted line of the polyamic acid (7c) are eliminated, and water (H ₂ O) is used as a by-product as in the curing reaction of the PBO precursor. Occurs.

In the formula (7), R ⁵ represents a divalent organic group constituting an organic diamine, R ⁶ represents a tetravalent organic group constituting a tetracarboxylic acid or a derivative thereof, and n represents a degree of polymerization. Examples of the diamine compound (7a) include phenylenediamine. Examples of the acid anhydride (7b) include pyromellitic anhydride.

  In the first light transmissive layer forming step of step s2, as shown in FIGS. 12A, 13A, and 14A, the gaps between the switch elements T are filled and the transparent elements are covered so as to cover the switch elements T. The optical material is applied to form first application layers 111, 120, and 130. By removing the solvent from the first coating layers 111, 120, and 121, the first light-transmitting layers 110, 121, and 131 are formed as shown in FIGS. 12B, 13B, and 14B. Is done.

  Since the 1st translucent layers 110, 121, and 131 are the layers which removed the solvent from the 1st application layers 111, 120, and 130, they consist of a solid component in translucent material. The first light-transmitting layers 110, 121, and 131 are affected by the surface tension, and the first surfaces 110a, 121a, and 131a, which are one surface in the thickness direction, are located on the substrate 31 side between two adjacent switch elements T. It is formed in a concave shape. When the content of the solid component in the translucent material is less than 25% by weight, the thickness of the first translucent layers 110, 121, and 131 is greatly reduced by the removal of the solvent. , 131 are greatly recessed toward the substrate 31 side.

  For example, as a translucent material containing a polyimide precursor, a translucent material having a low content of, for example, about 17% by weight of a polyimide precursor, which is a solid component, is used. When a light-transmitting material having a low content of less than 25% by weight is used, the thickness is greatly reduced by removing the solvent. For example, the thickness of the first light transmitting layer 131 is a value that is reduced by about 30 to 40% from the thickness of the first coating layer 131. Accordingly, as shown in FIG. 14B, the first light transmissive layer 131 is formed along the shape of the switch element T, and the first surface is the surface opposite to the substrate 31 in the thickness direction of the first light transmissive layer 131. 131 a is formed to be greatly recessed toward the substrate 31 between the switch elements T.

  In this embodiment, since a light-transmitting material containing a polybenzoxazole precursor is used, the solid component containing the polybenzoxazole precursor can be 25 wt% or more and 80 wt% or less, and by removing the solvent A decrease in the thickness of the first light transmissive layer 110 can be suppressed. Accordingly, when a translucent material having a solid component content of less than 25% by weight is used, for example, compared with a translucent material having a PBO precursor content of less than 25% by weight, The amount of decrease in thickness due to the removal of can be reduced. Therefore, since the degree of depression of the first surface 110a of the first light transmitting layer 110 toward the substrate 31, for example, the curvature of the first surface 110a can be reduced, the unevenness generated in the first light transmitting layer 110 can be reduced. Can do. Also in the case of using a translucent material containing a BCB compound, when the content of the BCB compound as a solid component is 25 wt% or more and 80 wt% or less, as in the present embodiment, FIG. As shown in FIG. 3, the unevenness generated in the first light transmitting layer 131 can be reduced.

  The first light-transmitting layers 110 and 131 formed in this way are exposed and developed with the developer in the recess forming step of step s3, and the recess 112 is formed as shown in FIGS. 12 (c) and 13 (c). , 122 are formed. When developing with a developer, if the translucent material has positive photosensitivity, the exposed portion is dissolved and removed in the developer, and the translucent material has negative photosensitivity. If so, the exposed portion remains, and the unexposed portion dissolves and is removed. At this time, since the portion that should remain is also exposed to the developer, it may elute into the developer and the thickness may decrease.

  For example, when the first light-transmitting layer 122 is formed of a light-transmitting material containing a benzocyclobutene compound that is a compound having a benzocyclobutene structure (hereinafter sometimes referred to as “BCB-based light-transmitting material”). As shown in FIG. 13C, the thickness of the first light transmissive layer 122 formed between the switch elements T, which should be left, is greatly reduced. This is presumably because the layer formed of the BCB translucent material is likely to be eluted from the inside even in a portion other than the portion that has become soluble in the developer by exposure. Accordingly, when the BCB-based translucent material is used, the thickness of the first translucent layer 121 is greatly reduced by development. For example, the thickness L2 of the first light transmissive layer 121 after development between the switch elements T is reduced to about 30% of the thickness L1 of the first light transmissive layer 121 before development.

  On the other hand, when the first light-transmitting layer 110 is formed of a light-transmitting material containing a PBO precursor as in the present embodiment, in a portion other than the portion that has become soluble in the developer by exposure, No elution occurs from the inside. Accordingly, since the amount of reduction in the thickness of the first light transmissive layer 110 due to development can be reduced as compared with the case where it is formed of a BCB-based light transmissive material, the substrate of the first light transmissive layer 110 between the switch elements T. An increase in the amount of depression toward the 31 side can be suppressed.

  The first light-transmitting layers 110 and 121 after development are cured in the first curing step of step s4. When the first light-transmitting layers 110 and 121 are cured, the volume decreases with the curing reaction, and the thickness decreases. For example, in the case of a PBO precursor, it is cured by a dehydration cyclization reaction. In the case of a benzocyclobutene compound, it is cured by a Diels-Alder reaction by heating. In the Diels-Alder reaction, the volume reduction due to curing is smaller than that in the dehydration condensation reaction, but the volume reduction amount due to the development described above is large. As shown in d), the switch elements T are formed to be greatly recessed toward the substrate 31 side.

  On the other hand, when the PBO precursor is used as in this embodiment, the volume reduction amount due to curing is larger than when the BCB-based translucent material is used, but the volume reduction amount due to development is small. Compared with the case where a BCB translucent material is used, the amount of recesses toward the substrate 31 between the switch elements T can be reduced.

  Second transparent layers 113 and 123 are formed on the surfaces of the cured first transparent layers 110 and 121. The second light transmissive layers 113 and 123 are formed by applying a light transmissive material and removing the solvent in the same manner as the first light transmissive layers 120 and 121. When the first light transmissive layer 110 is formed of a light transmissive material containing a PBO precursor as in the present embodiment, the thickness of the first light transmissive layer 110 formed between the switch elements T is as follows. The switch element T is in a state of being flattened by the first light transmitting layer 110 near the height h1. Since the translucent material for forming the second translucent layer 113 is applied so as to cover the first translucent layer 110 and the switch element T in such a state, the second translucent material between the switch elements T is applied. The amount of depression of the layer 113 toward the substrate 31 is reduced.

  Further, when the solvent is removed, it is affected by the surface tension. However, since the translucent material is filled in the recess 112 and applied so as to cover the first translucent layer 110, the second translucent layer 113 is The first light transmitting layer 110 is formed so as to be recessed toward the substrate 31 in the recess 112. Further, as described above, since the amount of the depression of the second light transmissive layer 113 toward the substrate 31 between the switch elements T is small, inversion of the unevenness occurs in the second light transmissive layer 113 as shown in FIG. Thus, the portion covering the first light transmissive layer 110 formed between the switch elements T protrudes beyond the portion formed in the concave portion 112 of the first light transmissive layer 110 and bulges away from the substrate 31. Formed. Therefore, the first surface 113 a, which is the surface opposite to the substrate 31 in the thickness direction of the second light transmissive layer 113, has a convex curved shape that protrudes in a direction away from the substrate 31.

  On the other hand, when the first light transmissive layer 121 is formed of a BCB-based light transmissive material, the amount of dent in the first light transmissive layer 121 between the switch elements T is large. Even if the translucent material is filled so as to be filled, the influence of the large amount of the recesses in the first translucent layer 121 is large, and the inversion of the unevenness in the second translucent layer 123 does not occur. Therefore, the waveguide formed between the switch elements T has a shape recessed toward the substrate 31 as shown in FIG.

  Further, through holes 115 and the like are formed in the second light transmissive layers 113 and 123 by photolithography, but the second light transmissive layer 123 formed of the BCB light transmissive material by development at this time has a further thickness. It decreases and becomes a shape recessed on the substrate 31 side. In contrast, in the present embodiment, since the second light transmissive layer 113 is formed of a light transmissive material containing a PBO precursor, the second light transmissive layer 113 is developed by development as compared with the case of being formed of a BCB light transmissive material. The amount of decrease in the thickness of the two light transmissive layers 113 is small. Therefore, the convex shape is maintained between the switch elements T even after the formation of the through-hole 115 and the like. In addition, the second light transmissive layer 113 is formed in a convex curved shape in which the first surface 114a protrudes in a direction away from the substrate 31 in a state where the through hole 115 is formed, so that the second light transmissive layer 114 is cured. The waveguide body 17 is formed in a convex curve shape in which the first surface 103 protrudes in a direction away from the substrate 31.

  As described above, in the present embodiment, since a translucent material containing a PBO precursor is used, the surface 103 has a convex curved surface 103 protruding in the direction Z1 separating from the substrate 31 between the switch elements T. It is possible to form the waveguide body 17 having the reflection condensing region 104 formed in a convex curved shape.

  The first light-transmitting layer 110 and the second light-transmitting layer 113 may be formed of different light-transmitting materials such as the type of PBO precursor or the ratio in the solid component, but are formed of the same light-transmitting material. It is preferable. By forming the first light-transmitting layer 110 and the second light-transmitting layer 113 with the same light-transmitting material, the refractive indexes of the first light-transmitting layer 110 and the second light-transmitting layer 113 can be made equal. Refraction and reflection at the interface between the first light transmissive layer 110 and the second light transmissive layer 113 can be prevented. In the present embodiment, the refractive indexes of the first light transmitting layer 110 and the second light transmitting layer 113 are selected from 1.5 to 2.0.

  The method of forming the waveguide body 17 is not limited to the present embodiment described above. As shown in FIG. 1, the waveguide body 17 having the convex reflection curved condensing region 104 convex outward is formed. Any material that can be formed may be used. For example, a translucent material is filled between the switch elements T and applied so as to cover the switch elements T. After removing the solvent to form a translucent layer, the translucent layer is exposed and developed using a gray mask. The waveguide 17 can also be formed by further curing. A “gray mask” is a mask having a different light transmittance in each portion.

  As the gray mask, for example, when the translucent material has positive photosensitivity, the portion covering the upstream portion of the waveguide direction X2 in the translucent layer formed between the switch elements T is the waveguide direction. A mask is used such that the light transmittance decreases toward the downstream side of X2. In the present embodiment, the waveguide body 17 is formed in a convex curved surface shape in which the first surface 103 protrudes in the direction away from the substrate 31 between the switch elements T. Therefore, the gray mask is formed between the switch elements T, for example. A mask is used in which the portion covering the light-transmitting layer is formed such that the light transmittance decreases as it goes from both ends to the center between the switch elements T. Thus, when forming the waveguide body 17 using a gray mask, as a translucent material, it is not limited to the translucent material containing a PBO precursor, For example, the translucent material containing a BCB compound or a polyimide precursor is used. A light material or the like may be used. These translucent materials contain a photosensitizer when a resin precursor such as a BCB compound or a polyimide precursor does not have photosensitivity.

  Further, by using dry etching, the waveguide body 17 is not limited to PBO resin but can be formed of, for example, BCB resin. When using dry etching, for example, a translucent material is applied and a solvent is removed to form a translucent layer, and after further curing, dry etching is performed using a gray mask to project outward. Thus, it is possible to form the convex reflection curved condensing region 104.

  FIG. 15 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. 15, the horizontal axis represents the anode voltage, and the vertical axis represents the anode current. FIG. 15 also shows a load line 72. The light-emitting element L, the switch element T, and the scan start switch element T0 include an off-state point b where the characteristic curve representing the voltage-current characteristic and the load line 72 intersect, and an a-state where the characteristic curve and the load line 72 intersect. Transition between points. 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 . In the light emitting element L, the initial threshold voltage is a threshold voltage in a non-selected state in which a trigger signal is not applied to the gate 19, and a threshold voltage in a non-light receiving state that is not received by the switch element T. In the scan start switch element T0, the threshold voltage is in a non-selected state in which the trigger signal is not 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. 15, voltage smaller than the V _BO The threshold voltage drops to V _TH which is. In the switch element T, by receiving the threshold voltage has V _BO, as indicated by the arrow P1 in FIG. 15, drops into the V _TH is smaller voltage than the V _BO. Since the optical transfer array device 1 has a high light guide rate by the waveguide 17, when the same intensity light is emitted from the switch element T, the threshold voltage is more reliably compared to the conventional optical transfer array device. Can be reduced to a predetermined value. In addition, the threshold voltage can be reduced to a predetermined value in a shorter time.

  In the present embodiment, the switch element T is laminated from the interface between the first P-type semiconductor layer 43 and the second N-type semiconductor layer 44 in a cross section perpendicular to the lamination direction Z1 of the second N-type semiconductor layer 44. Since the light-emitting thyristor 20 having a high light-receiving efficiency is formed so as to decrease with increasing distance from the direction Z1, the threshold voltage decreases in the stacking direction Z1 of the second N-type semiconductor layer 44. The vertical cross section becomes larger than the case where the vertical cross section is not formed so as to decrease from the interface between the first P-type semiconductor layer 43 and the second N-type semiconductor layer 44 in the stacking direction Z1. Therefore, the threshold voltage can be more reliably reduced to a predetermined value.

  FIG. 16 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 is inputted from the outside and outputs the first to third scanning signals φ1 to φ3 and the start signal φS in synchronization with each other based on the reference clock pulse signal, and the scanning signal transmission path 15 and the start signal transmission Each is given to the road 16. 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. 17 shows that the drive means 73 gives a start signal φS to the start signal transmission path 16, a first scanning signal φ1 to give to the first scanning signal transmission path 15a, a second scanning signal φ2 to give 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. 17, the horizontal axis is 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 the threshold voltage or threshold in the light receiving state or selected state of each element. Less than current. 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 φ3. 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 N-type semiconductor layer 44 due to the generation of carriers lower the Fermi level of the second N-type semiconductor layer 44, thereby the first P-type semiconductor layer 43 and the second N-type semiconductor layer 44. An avalanche phenomenon is likely to occur at the junction with the 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 the lowest value of 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. Rather than a higher voltage or higher 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, adjacent switch elements 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 (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 the high level is selected to be about 1 μsecond (μsecond). Therefore, the time between the time t2 and the 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 layer 36 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. In this way, the switch element T1 can change the voltage applied to the gate 19 and the back electrode layer 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, 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 _VH 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 can be selectively turned on to emit light. it can.

  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 (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 It is selected to be about 1/10 (1/10) of the time when the third scanning signal φ3 becomes 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. By transmitting the first to third scanning signals φ1 to φ3 and supplying the first to third scanning signals φ1 to φ3 to each switch element T, from the upstream side to the downstream side in the second direction X2 of the arrangement direction X. The light emitting state of the switch element T can be transferred to the other side, in other words, optical scanning can be performed.

  According to the optical transfer array device 1 described above, since the light guide by the waveguide body 17 provided between two adjacent switch elements T is high, the intensity of light emitted from the switch elements T is the same. In addition, the threshold voltage can be greatly reduced as compared with the conventional optical transfer array device. As a result, the threshold voltage can be lowered more reliably than the signal voltage of the scanning signal φ, so that the switching element T can be reliably turned on to emit light by applying the scanning signal φ. Therefore, even if the intensity of light emitted from each switch element T varies slightly, the light emission state of the switch element T can be transferred reliably, so that the light emitting device 10 can perform optical scanning more reliably. it can.

  Further, according to the light emitting device 10, the switch elements T have high light receiving efficiency, and the threshold voltage is lower than that of the conventional switch elements only by irradiating weak light for a short time. Can be shortened (t3-t1, t7-t2, t9-t6). Thereby, the light emitting device 10 can perform optical scanning at high speed.

  Further, since the switch element T has high light receiving efficiency, the intensity of light applied to the switch element T to which the light emission state should be transferred can be set to a weak value, and the intensity of light to be emitted by each switch element T is weak. Can be set to a value. Therefore, the load applied to each switch element T can be reduced, and the life of the switch element T can be extended. Thereby, the lifetime of the optical transfer array device and the light emitting device 10 including the switch element T can be extended.

  FIG. 18 is a side view showing a basic configuration of an 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 is mounted on a circuit board on which the driving unit 17 is provided.

  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 four lens arrays 88Y, 88M, 88C, and 88K that are the light collecting means, the circuit board on which the light emitting device 10 and the driving means 17 are mounted, and the lens array 88 are held. Four first holders 89Y, 89M, 89C and 89K, four photosensitive drums 90Y, 90M, 90C and 90K, four developer supply means 91Y, 91M, 91C and 91K, and a transfer belt 92 which is a transfer means. And four cleaners 93Y, 93M, 93C and 93K, four chargers 94Y, 94M, 94C and 94K, a fixing means 95 and a control means 96. It is made.

  Each light emitting device 10 is driven by the driving means 17 based on the color image information of each color. For example, the length of the four light emitting devices 10 in the arrangement direction X is selected from 200 mm to 400 mm, for example.

  Light from the light emitting element T of each light emitting device 10 is condensed and applied to each of the photosensitive drums 90Y, 90M, 90C, and 90K via the lens array 88. The lens array 88 includes, for example, a plurality of lenses disposed on the optical axis of the light emitting element, and is configured by integrally forming these lenses.

  The circuit board on which the light emitting device 10 is mounted and the lens array 88 are held by the first holder 89. By the first holder 89, alignment is performed so that the light irradiation direction of the light emitting element T and the optical axis direction of the lenses of the lens array 88 substantially coincide.

  Each of the photoconductive drums 90Y, 90M, 90C, and 90K is formed, for example, by adhering a photoconductive layer on the surface of a cylindrical substrate, and the outer peripheral surface receives light from 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.

  The exposed photosensitive drums 90Y, 90M, 90C, and 90K are sequentially exposed at the periphery of the photosensitive drums 90Y, 90M, 90C, and 90K toward the downstream side in the rotational direction with respect to the electrostatic latent image forming positions. Developer supplying means 91Y, 91M, 91C, 91K for supplying developer to the transfer belt 92, cleaners 93Y, 93M, 93C, 93K, and chargers 94Y, 94M, 94C, 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 90Y, 90M, 90C, and 90K.

  The photosensitive drums 90Y, 90M, 90C, and 90K are held by a second holder (not shown), and the second holder and the first holder 89 are relatively fixed. The photoconductor drums 90Y, 90M, 90C, and 90K are aligned so that the rotation axis directions of the respective light emitting devices 10 and the arrangement direction X of the light emitting devices 10 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 90Y, 90M, 90C, and 90K are rotated by a rotation driving unit.

  The control unit 96 supplies a clock signal and image information to the driving unit 17 described above, and also rotates and drives the photosensitive drums 90Y, 90M, 90C, and 90K, developer supply units 91Y, 91M, 91C, and 91K, Each part of the transfer means 92, the charging means 94Y, 94M, 94C, 94K and the fixing means 95 is controlled.

  The image forming apparatus 87 includes the light emitting device 10 that can reliably emit the light emitting thyristors 20 sequentially in the arrangement direction X2 and transmit the trigger signals in order in the arrangement direction X2. Therefore, the photosensitive drums 90Y, 90M, Light can be accurately irradiated to the predetermined positions of 90C and 90K. As a result, the image forming apparatus 87 can form an excellent quality recorded image free from image defects such as white spots.

  Further, the image forming apparatus 87 includes the light emitting device 10 that can sequentially emit the light emitting thyristors 20 in the arrangement direction X2 and transmit the trigger signals in order in the arrangement direction X2. It is possible to form an excellent quality image in a short time. In addition, since the image forming apparatus 87 includes the light emitting device 10 having a long lifetime, the lifetime of the device can be extended.

  Further, 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 the gate of each switch element T can be reduced. It is not necessary to connect a load resistor or the like connected between the diode for designating the transfer direction and the power source. 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 the transmission path for supplying the power required for the scanning start switch element T0 is specially provided. There is no need to provide it.

  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, the scanning start switch element T0 does not emit light unless a trigger signal is given to a predetermined portion and the scanning signal φ is not given, so that even if the trigger signal is given undesirably, it is prevented from emitting light. be able to.

  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, it is possible to prevent the light amount of the light emitting element L from being reduced or increased, and a stable light amount 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 line 12 are prevented from being short-circuited.

  Further, according to the optical transfer array device 1 of the present embodiment, the light emitting unit 100 and the light receiving unit 101 of the switch element T are provided in a stacked manner in the fifth direction Z1, which is a direction perpendicular to the waveguide direction X2. Compared with the case where the part 100 and the light receiving part 101 are arranged in a direction parallel to the waveguide direction X2, the switch element T can be reduced in size with respect to the waveguide direction X2. Therefore, since the integration density of the switch elements T in the switch element array 13 can be increased, the degree of freedom in designing the switch element array 13 can be increased.

  In the optical transfer array device 1 of the present embodiment described above, the switch element T which is a light transfer light emitting element is the light emitting thyristor 20, but the light transfer light emitting element is not limited to the light emitting thyristor. In the optical transfer array device according to another embodiment of the present invention, the light transfer light emitting element is a light emitting diode (abbreviated as LED), a laser diode (abbreviated as LD), a photodiode (abbreviated as PD) or a phototransistor. It may be an element. By appropriately combining these semiconductor elements, a light-emitting element for light transfer is realized. For example, the light transfer light emitting element may include a light emitting diode as a light emitting portion and a photodiode as a light receiving portion.

  Further, in the optical transfer array device 1 of the present embodiment, the light emitting unit 100 and the light receiving unit 101 of the switch element T that is a light transmitting light emitting element are stacked in the fifth direction Z1, which is a direction perpendicular to the waveguide direction X2. However, in the optical transfer array device according to still another embodiment of the present invention, the light emitting unit and the light receiving unit of the light transmitting light emitting element may be arranged side by side in a direction parallel to the waveguide direction X2. In this case, each light transfer light emitting element is arranged such that the light emitting part is adjacent to the light receiving part of the light transferring light emitting element adjacent to the waveguide direction X2, and the light receiving part is in a direction opposite to the waveguide direction X2. Are arranged so as to be adjacent to the light emitting portion of the light emitting element for light transfer adjacent to the second direction X1. When the light emitting unit and the light receiving unit are arranged side by side in a direction parallel to the waveguide direction X2, the light-transmitting light emitting element includes, for example, a light emitting element that is a light emitting unit and a light receiving element that is a light receiving unit. . For example, a light emitting diode or a laser diode is used as the light emitting element. For example, a photodiode or a phototransistor is used as the light receiving element.

  In the light emitting device according to yet another embodiment of the present invention, between the substrate 31 and the first N type semiconductor layer 32 of the light emitting element L, between the substrate 31 and the first N type semiconductor layer 42 of the switch element T. A buffer layer made of an N-type semiconductor may be provided between the substrate 31 and the first N-type semiconductor layer 42 of the scanning start switch element T0. With this configuration, a semiconductor layer with improved crystallinity can be formed on the substrate 31, 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.

  In the light emitting device according to still another embodiment of the present invention, an ohmic contact layer made of a P-type semiconductor may be provided between the light emission signal transmission line 12 and the second P-type semiconductor layer 35. By providing this ohmic contact layer, the ohmic property between the light emission signal transmission line 12 and the second P-type semiconductor layer 35 can be improved.

  In the light emitting device according to still another embodiment of the present invention, the retracting portion has a cross section perpendicular to the thickness direction Z that gradually decreases as the distance from the interface with the projecting portion 47 increases in the thickness direction Z1. It may be a simple shape. Further, the retracting portion may have a shape such that a cross section perpendicular to the thickness direction Z continuously decreases as the cross section moves away from the interface with the protruding portion 47 in the fifth direction Z1, which is one of the thickness directions.

  In the light emitting device according to still another embodiment of the present invention, the distance between the side surfaces in the first direction X1, which is one of the arranging directions of the retracting portion 46 and the protruding portion 47, and the other of the arranging direction of the retracting portion 46 and the protruding portion 47 are the other. The interval W between the side surfaces in the second direction X2 and the interval W8 between the side surfaces in the fourth direction Y2, which is the other in the width direction of the retracting portion 46 and the protruding portion 47, may be selected to be different from each other.

  In the light emitting device according to yet another embodiment of the present invention, the substrate 31 may be an insulating substrate or a semi-insulating substrate. 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 above-described back electrode layer 36 is not formed on the other surface 31b in the thickness direction Z of the substrate 31, and the first N-type semiconductor layer 32 of the light emitting element L, the first of the switch elements T A cathode electrode is formed on one N-type semiconductor layer 42 and the first N-type semiconductor layer 42 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, a metal layer that functions as an anode terminal together with the scanning signal transmission path 15 may be formed by being stacked on the ohmic contact layer 25 of the switch element T. With such a configuration, the electric field to each semiconductor layer of the switch element T can be made uniform, and the emission intensity of light emitted from the switch element T can be increased. As a result, the adjacent switch element T can be turned on more reliably, so that the light emitting element L that should emit light can be made to emit light more reliably.

  In the light emitting device of still another embodiment of the present invention, a metal layer that functions as an anode terminal together with the light emitting signal transmission path 12 may be formed by being stacked on the second P-type semiconductor layer 35 of the light emitting element L. . 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 the light emitting device according to still another embodiment of the present invention, the light shielding layer 18 is made of a material having a high reflectance of light having a wavelength emitted from the switch element T and a lower refractive index than the insulating layer 17 that is the waveguide body 17. It may be formed. When formed of such a material, the light transmitted through the waveguide body 17 among the light from the switch element T is reflected without being absorbed by the light shielding layer 18. As a result, the amount of light incident on the adjacent switch element T can be increased, and the light receiving efficiency of the switch element T can be increased. Therefore, the switch element T can be turned on more reliably.

  In a light emitting device according to still another embodiment of the present invention, the conductivity type of each semiconductor layer may be reversed, the P type semiconductor layer may be an N type semiconductor layer, and the N type semiconductor layer may be a P type semiconductor layer. In this case, three layers close to the substrate 31 function as a PNP type phototransistor portion, which is the light receiving portion 101, and two layers close to the light emission signal transmission path 12 or the scanning signal transmission path 15 function as a PN type light emission portion. Even if the conductivity type of each semiconductor layer is reversed, by reversing the polarity of the bias voltage, the same effect as that of the light-emitting device of the above-described embodiment can be obtained. In this case, the substrate 31 is a P-type semiconductor substrate made of a P-type semiconductor material.

  In a light emitting device according to still another embodiment of the present invention, a high level voltage or current of the light emission signal φE output from the driving unit 73 is given by a trigger signal by the switch element T connected to the light emission signal transmission path 12. A higher voltage or higher current than the lowest value of the threshold voltage or threshold current of other light emitting elements L other than the light emitting element L may be selected. The light emission signal transmission path 12 is connected to the connection means 14 via the resistance element Rφ, and the light emission signal transmission path to which the light emission element L whose threshold voltage or threshold current has been reduced by the application of the trigger signal is connected. When a light emission signal φE having a voltage or current higher than the minimum value of the threshold voltage or threshold current of another light emitting element L connected to the light emission signal transmission line 12 is applied to the light emission signal φE, A voltage divided by the resistance element Rφ is applied to the light emitting signal transmission path 12 via Rφ. A voltage divided by the resistance element Rφ is gradually applied to each light emitting element L, and among the plurality of light emitting elements L connected to the light emitting signal transmission path 12, the light emitting element to which a trigger signal is given. The voltage or current given to L becomes the earliest 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 control of the light emission signal φE by the driving means 73 becomes easy.

  In still another embodiment of the present invention, the high level of the scanning signal φ output from the driving means 73 is a switch whose threshold voltage or threshold current is reduced by receiving light from the adjacent switch element T. The voltage or current is selected to be higher than the average value of the threshold voltage or threshold current of the other switch elements T connected to the scanning signal transmission line 15 to which the element T is connected. 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 average value of the 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. 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, adjacent switch elements 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.

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

  In the light emitting device according to yet another embodiment of the present invention, the high level of the scanning signal φ output from the driving means 73 is the threshold voltage or threshold of all the switch elements L connected to the scanning signal transmission line 15. It may be selected higher than the current. Even with such a configuration, the same effect can be achieved, and the high-level voltage or current of the scanning signal φ is changed by the driving unit 73 to the threshold voltage or threshold current that fluctuates in the switch element T. Since it can be determined regardless, the design of the driving means 73 is facilitated.

  In the light emitting device according to the embodiment of the present invention, the numbers of the light emitting elements Li and the switch elements Tj are configured to be equal. However, in the light emitting device of still another embodiment of the present invention, a plurality of switch elements T are included in the switch element T. The light emitting element L may be made to correspond. That is, the gate 24 of one switch element T and the gates 19 of a plurality of light emitting elements L may be connected. 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. For example, the first N-type semiconductor layer 42 may be configured by stacking a plurality of N-type semiconductor layers, and the first P-type semiconductor layer 43 is configured by stacking a plurality of P-type semiconductor layers. The second N-type semiconductor layer 44 may be formed by stacking a plurality of N-type semiconductor layers, and the second P-type semiconductor layer 45 may be formed by stacking a plurality of P-type semiconductor layers. The ohmic contact layer 25 may be configured by stacking a plurality of P-type semiconductor layers.

(Example)
The optical transfer array device 1 shown in FIG. 1 was manufactured as follows. First, a switch element T having a mesa structure was produced on the substrate 31. The interval W3 between two adjacent switch elements T was 20 μm. The dimension of the laminated body X composed of the substantially rectangular parallelepiped retracting portion 46, the second P-type semiconductor layer 45, and the ohmic contact layer 25 was 24 μm, and the width direction Y was 34 μm. In addition, the dimension in the arrangement direction X of the stacked body including the first N-type semiconductor layer 42, the second P-type semiconductor layer 45, and the protrusion 47 is set to 30 μm, and the dimension in the width direction Y is set to 40 μm. The evacuation part 46 was formed so as to extend from the central part in the arrangement direction X and the width direction Y of the protrusions 47 in the fifth direction Z1, which is one of the thickness directions. The thickness in the thickness direction Z of the first N-type semiconductor layer 42 is 500 nm, the thickness in the thickness direction Z of the first P-type semiconductor layer 43 is 200 nm, and the thickness in the thickness direction Z of the protrusion 47 is 500 nm. The thickness of the retracting portion 46 in the thickness direction Z is 500 nm, the thickness of the second N-type semiconductor layer 44 in the thickness direction Z is 1000 nm, and the thickness of the second P-type semiconductor layer 45 in the thickness direction Z is 800 nm.

  Next, as shown in FIG. 11, a translucent material was applied using a spin coater to form a first application layer 111 having a thickness S1 of 5 μm. The light-transmitting material contains 20% by weight of a polybenzoxazole precursor obtained by reacting 3,3′-dihydroxybenzidine and isophthalic acid by the acid chloride method, and β, β-bis (4 -Hydroxyphenyl) propane-type bisnaphthoquinone- (1,2) -diazide- (2) -5-sulfonic acid positive-type photosensitive translucent material (solvent: γ-butyrolactone, solid A component content of 40% by weight was used. The rotation speed of the spin coater was 3000 rotations / minute. The substrate 31 on which the first coating layer 111 was formed was pre-baked on a hot plate heated to 180 ° C. for 3 minutes to remove the solvent, thereby forming the first light transmitting layer 110.

Of the portion covering the switch element T of the first light transmissive layer 110, a predetermined portion to be the concave portion 112 was exposed for 13 seconds at an irradiation intensity of 17 mW / cm ² using a mask. Alkaline developer (trade name: TMAH 2.38%, manufactured by Tama Chemical Industry Co., Ltd.), which is an aqueous solution containing 2.38% by weight of tetramethylammonium hydroxide, for the substrate 31 including the exposed first light-transmitting layer 110. The film was dipped in, rocked for 90 seconds, and developed. As a result, the switch element T was partially exposed, and a recess 112 was formed as a through hole. The width W10 of the recess 112 in the waveguide direction X2 was 12 μm. The developed first light transmissive layer 110 was heated to 350 ° C. and cured. The amount of dent d1 between the switch elements T of the first light transmissive layer 110 after curing was 0.85 μm.

  Next, the electrode layer is formed by exposing the semiconductor layer in the portion where the electrode is to be formed by wet etching using a mixed solution of sulfuric acid and hydrogen peroxide solution, and then, in the same manner as the first coating layer 111, The material was applied by a spin coater to form a second coating layer 114 having a thickness S2 of 5 μm. In the same manner as the first coating layer 111, pre-baking was performed to remove the solvent, and the second light-transmitting layer 113 was formed. A predetermined portion of the formed second light transmitting layer 113 as a through hole 115 was exposed in the same manner as the first light transmitting layer 110 and developed to form the through hole 115. The second light transmissive layer 113 in which the through hole 115 was formed was cured by heating to 350 ° C. to form the waveguide body 17. As shown in FIG. 19A, the formed waveguide body 17 has a convex curved surface shape in which the first surface 103 turns into a convex shape between the switch elements T and protrudes away from the substrate 31, that is, outward. It was formed in a convex curved surface shape. The protruding amount d2 of the waveguide body 17 between the switch elements T was 0.66 μm. A conductive layer was formed as an anode terminal in the through hole 115, and a back electrode layer 36 was formed on the second surface 31 b of the substrate 31 to obtain an optical transfer array device. The obtained optical transfer array apparatus is hereinafter referred to as “optical transfer array apparatus A”.

(Comparative example)
As a comparison for comparing the characteristics of the optical transfer array device of the present invention, only the method of forming the waveguide is changed, and the other fabrication conditions are the same as those of the optical transfer array device A of the embodiment. A transfer array device was manufactured. The waveguide material contains 20% by weight of the benzocyclobutene (BCB) compound represented by the structural formula (5) described above, and bis (β-β-bis (4-hydroxyphenyl) propane) as a photosensitizer. Positive photosensitive BCB-based translucent material containing 20% by weight of naphthoquinone- (1,2) -diazide- (2) -5-sulfonic acid ester (solid component content 40% by weight, manufactured by Dow Chemical Co., Ltd.) ) Was used. The thermosetting shrinkage ratio of the layer formed of the light transmissive material is about 8%. The optical transfer array device obtained in this comparative example is hereinafter referred to as “comparative optical transfer array device B”.

  Specifically, the optical transfer array apparatus B was manufactured as follows. First, the switch element T was fabricated in the same manner as the optical transfer array apparatus A. Subsequently, an adhesion layer having a thickness of 10 nm (100 mm) was formed so as to cover the switch element T and the substrate 31 using an adhesion enhancer for BCB (trade name: AP3000, manufactured by Dow Chemical Co., Ltd.). The aforementioned adhesion enhancer for BCB contains, as a main component, a siloxane compound having a structural unit represented by the following structural formula (8), and this siloxane compound is a hydroxyl group (—OH) or oxygen atom ( O) improves the adhesion between the semiconductor layer and the BCB compound.

The BCB-based translucent material described above was applied to the surface of the formed adhesion layer using a spin coater to form a first coating layer 120 having a thickness of 5 μm as shown in FIG. The rotation speed of the spin coater was 5000 rotations / minute. The substrate 31 on which the first coating layer 120 was formed was pre-baked for 20 minutes in a clean oven heated to 70 ° C. to remove the solvent, thereby forming the first light transmissive layer 121. A predetermined portion of the formed first light transmitting layer 121 as a concave portion 122 was exposed for 10 seconds at an irradiation intensity of 10 mW / cm ² . The exposed first light-transmitting layer 121 was subjected to paddle development using a developer for a BCB-based light-transmitting material (trade name: DS2100, Dow Chemical Company, mixed solution of glycol ether and synthetic isoparaffin-based hydrocarbon). As a result, a pattern in which the switch element T was partially exposed was formed. The width W12 of the recess 122 in the waveguide direction X2 is the same as the width W10 of the recess 112 formed in the first light transmitting layer 110 in the above-described embodiment. The developed first light transmitting layer 121 was heated to 300 ° C. and cured. The dent L3 between the switches T of the first light-transmitting layer 121 after curing was 1.8 μm.

  Next, by wet etching using a mixed solution of sulfuric acid and hydrogen peroxide solution, an electrode layer is formed by exposing a portion of the semiconductor layer where the electrode is to be formed, and then a second layer having a thickness of 5 μm is formed in the same manner as the first light-transmitting layer 121. After forming the light transmissive layer 123, the through hole 115 was formed by exposure and development, and further heated and cured to form the waveguide 124. As shown in FIG. 19B, the formed waveguide 124 has the first surface 124a recessed toward the substrate 31 between the switch elements T, and the amount L4 of the recess is 0.7 μm. A conductive layer was formed as an anode terminal in the through hole 115, and a back electrode layer 36 was formed on the second surface 31 b of the substrate 31 to obtain a comparative optical transfer array device B.

[Evaluation]
In order to compare the light transfer efficiency of the light transfer array device A and the comparison light transfer array device B, the light emission intensity of the light emission side switch element, which is the switch element T on the light emission side, and the light emission side switch element T are adjacent to each other. The relationship between the photocurrent generated by light reception in the light-receiving-side switch element, which is the switch element T, was investigated. Specifically, in a state where light having a predetermined intensity is incident on the light emission side switch element, the light emission intensity of the light emission side switch element is increased by increasing the voltage applied between the anode terminal and the back electrode layer 36. Then, the magnitude of the photovoltaic current flowing through the light receiving side switching element was measured. The voltage between the anode terminal of the light emitting side switch element and the back electrode layer 36 and the photocurrent flowing through the light receiving side switch element were measured by bringing the probe of the ampere meter into contact with the anode terminal and the back electrode layer 36. .

  FIG. 20 is a graph showing a measurement result of the relationship between the light emission intensity of the light emitting side switch element and the photocurrent flowing in the light receiving side switch element in the light transfer array device A and the comparative light transfer array device B. . In the graph shown in FIG. 20, the horizontal axis represents the light emission intensity of the light emitting side switch element, and the vertical axis represents the photocurrent flowing through the light receiving side switch element. In the graph shown in FIG. 20, the light emission intensity is represented by a relative magnitude based on a predetermined value E, and the photocurrent is represented by a relative magnitude based on a predetermined value I. In the graph shown in FIG. 20, the measurement result of the relationship between the light emission intensity of the light emitting side switch element and the photocurrent of the light receiving side switch element in the light transfer array device A of the present invention is represented by a solid line, and the comparison light transfer array device The measurement result of the relationship between the light emission intensity of the light emission side switch element and the photocurrent of the light reception side switch element in B is represented by a broken line.

  From the measurement results shown in FIG. 20, the light transfer array device A of the present invention is generated in the light receiving side switch element when light is emitted from the light emitting side switch element with the same intensity as compared with the comparative light transfer array device B. It was found that the magnitude of the photocurrent was about 20% larger. From this, it can be seen that the optical transfer array device A of the present invention has a higher light guide rate and higher optical transfer efficiency than the comparative optical transfer array device B. This is because, in the optical transfer array apparatus A of the present invention, the angle formed between the normal 150 of the first surface 103 of the waveguide 17 and the incident light 151 shown in FIG. Is an incident angle θ ′ that is an angle formed between the normal line 152 of the first surface 124a of the waveguide 124 of the comparative optical transfer array device B shown in FIG. 19B and the incident light 153. This is thought to be due to the increase.

  As described above, according to the present invention, it is possible to provide an optical transfer array device in which the light guide rate of the waveguide is improved, a light emitting device including the optical transfer array device, and an image forming apparatus.

  The present invention is not limited to the above-described embodiments, and various changes and improvements can be made without departing from the scope of the present invention.

1 is a partial cross-sectional view illustrating a basic configuration of a light emitting device 10 according to an embodiment of the present invention. 2 is a partial plan view showing a basic configuration of the light emitting device 10. FIG. 2 is a partial plan view showing a basic configuration of the light emitting device 10. FIG. FIG. 4 is a partial cross-sectional view illustrating a basic configuration of the light-emitting device 10 as viewed from a section line IV-IV in FIG. 3. It is sectional drawing which expands and shows the part of the waveguide 17 of the optical transfer array apparatus 1 shown in FIG. FIG. 3 is a cross-sectional view schematically showing a waveguide body 124 having a concave curved surface 124a between switch elements T. It is sectional drawing which shows typically the relationship between the shape of the surface of a waveguide, and an incident angle. FIG. 5 is a partial cross-sectional view illustrating a basic configuration of the light-emitting device 10 as viewed from a section line VV in FIG. 3. FIG. 4 is a partial cross-sectional view illustrating a basic configuration of the light-emitting device 10 as seen from a section line VI-VI in FIG. 3. It is a flowchart which shows the procedure of the manufacturing method of the optical transmission array apparatus which is one Embodiment of this invention. FIG. 3 is a cross-sectional view schematically showing how the optical transfer array device 1 is manufactured. It is sectional drawing which shows typically a mode that the waveguide body 17 is formed using the translucent material containing a PBO precursor. It is sectional drawing which shows typically a mode that a waveguide body is formed using the translucent material containing a cyclobenzobutene compound. It is sectional drawing which shows typically a mode that a waveguide body is formed using the translucent material containing a polyimide precursor. 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. FIG. 4 is a circuit diagram showing a part of an equivalent circuit showing a basic configuration of the light emitting device 10 shown in FIG. 3. 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 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. 2 is a side view showing a basic configuration of an image forming apparatus 87 having a light emitting device 10. FIG. It is sectional drawing which shows the basic composition of the optical transfer array apparatus A and the comparative optical transfer array apparatus B. It is a figure which shows the graph showing the measurement result of the relationship between the light emission intensity of the light emission side switch element in the light transfer array apparatus A and the light transfer array apparatus for a comparison, and the photocurrent which flows into the light reception side switch element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical transfer array apparatus 10 Light-emitting device 11 Light-emitting element array 13 Switch element array (Light-emitting element array for optical transfer)
17 Waveguide (insulating layer)
18 light shielding layer 20 light emitting thyristor 31 substrate 36 back electrode layer 42 first N type semiconductor layer 43 first P type semiconductor layer 44 second N type semiconductor layer 45 second P type semiconductor layer 46 retracting portion 47 protruding portion 100 Light emitting part 101 Light receiving part

Claims (7)

A substrate,
A plurality of light-transfer light-emitting elements arranged on the substrate at intervals, each light-transfer light-emitting element being in a light receiving state for receiving light from the adjacent light-transfer light-emitting elements A light-emitting element array for light transfer whose threshold voltage or threshold current is smaller than the threshold voltage or threshold current in the non-light-receiving state;
A waveguide provided between two adjacent light transfer light-emitting elements, and guides light from one of the light transfer light-emitting elements to the other light transfer light-emitting element, The surface has a reflective condensing region, the reflective condensing region is formed in a convex curved shape that is convex outward, and light from the one light transfer light emitting element is reflected in the reflective condensing region. An optical transfer array device comprising: a waveguide formed so as to be incident on the other light transfer light emitting element when reflected. Each light-emitting element for light transfer has a light-emitting part and the light-receiving part,
2. The optical transfer array device according to claim 1, wherein the light emitting unit and the light receiving unit are provided on the substrate in the order of the light receiving unit and the light emitting unit. Each light-emitting element for light transfer is
A first N-type semiconductor layer;
A first P-type semiconductor layer stacked on one surface portion in the thickness direction of the first N-type semiconductor layer;
A second N-type semiconductor layer stacked on one surface portion in the thickness direction of the first P-type semiconductor layer;
A light-emitting thyristor including a second P-type semiconductor layer stacked on one surface portion in the thickness direction of the second N-type semiconductor layer,
A cross section perpendicular to the stacking direction of the first P-type semiconductor layer or the second N-type semiconductor layer extends from the interface between the first P-type semiconductor layer and the second N-type semiconductor layer in the stacking direction. 3. The optical transfer array device according to claim 1, wherein the optical transfer array device is formed so as to decrease as the distance increases. A plurality of light-transmitting light-emitting elements that have a threshold voltage or threshold current when receiving light from an adjacent light-transfer light-emitting element; An array forming step of forming a plurality of light transfer light emitting elements having a smaller current than the threshold current on the substrate at a distance from each other to form a light transfer light emitting element array;
A light-transmitting material containing a solid component containing a polybenzoxazole precursor and a solvent is filled between the light-emitting light-emitting elements and applied so as to cover each light-emitting light-emitting element, and the solvent is removed. A first light transmissive layer forming step of forming the first light transmissive layer by,
A step of forming a recess by partially removing a portion of the first light-transmitting layer that covers the light-emitting element for light transfer by exposing and developing the first light-transmitting layer;
A first curing step of curing the first light-transmitting layer;
The second light-transmitting layer is formed by applying the light-transmitting material so as to cover the first light-transmitting layer which is filled and hardened in the concave portion, and forming the second light-transmitting layer by removing the solvent. Process,
And a second curing step of curing the second light-transmitting layer.   5. The method for manufacturing an optical transfer array device according to claim 4, wherein the translucent material has a content of the solid component of 25 wt% or more and 80 wt% or less. 4. The optical transfer array device according to claim 1, wherein each of the light-transfer light-emitting elements has a threshold voltage or threshold current that is greater than a threshold voltage when the light-receiving element is in the light-receiving state, and is not receiving light. Scanning signal transmission means for transmitting a scanning signal having a signal voltage or a signal current smaller than a threshold voltage or a threshold current when in a state, each light-transmitting light-emitting element is in the light-receiving state and the scanning signal An optical transfer array device that generates a trigger signal at a predetermined site when
A plurality of light emitting elements arranged at intervals from each other, and each of the light emitting elements is in a non-selected state when a threshold voltage or a threshold current is in a selected state where a trigger signal is given to a predetermined portion. Threshold voltage when the threshold voltage or threshold current is lower than the threshold voltage or threshold current when the threshold voltage or threshold current is greater than the threshold voltage or threshold current when the selected state is selected and when the selected state is not selected. Or a light emitting element array that emits light when a light emission signal having a signal voltage or a signal current smaller than a threshold current is given;
A light emission signal transmission means for transmitting the light emission signal to each of the light emitting elements;
A light emitting apparatus comprising: a predetermined portion of the light emitting element; and a connecting means for connecting the predetermined portion of the light transfer light emitting element. A light emitting device according to claim 6;
Driving means for driving the light emitting device based on image information;
Condensing means for condensing light from the light emitting element of the light emitting device on a charged photosensitive drum;
Developer supplying means for supplying the developer to the exposed photosensitive drum by which light from the light emitting device is condensed on the photosensitive drum by the condensing means;
Transfer means for transferring an image formed by the developer on the photosensitive drum to a recording sheet;
An image forming apparatus comprising: fixing means for fixing the developer transferred to the recording sheet.

Images