JP2001130051A - Exposure device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure device capable of forming a latent image at a high speed, capable of preventing optical cross talk and capable of forming a highly fine latent image. SOLUTION: In an exposure device 30 equipped with a light emitting element row group constituted of light emitting element rows CH12, CH21 wherein a large number of light emitting elements are arranged on a plane zigzag over two or more stages and an image forming means forming an image on an image carrier 2 by the luminous flux from the light emitting element row group, the light emitting element rows are formed on a light emitting element chip equipped with an electrode controlling the respective light emitting elements and the electrode is positioned on the light emitting element chip at the end part in the light emitting element arranging direction thereof and wiring for applying voltage or current to the electrode is connected to the electrode and the image forming means comprises the lens groups corresponding to the light emitting element rows in a ratio of 1: 1 and the lenses 3b, 3c of the lens groups are constituted so as not to form the images of the electrode and the wiring and light emitting timing is controlled at every light emitting element row corresponding to the distance on the image carrier on which luminous flux is formed into an image from each of the light emitting element rows.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus used as an exposure system of a printer, a facsimile, a copying machine, etc. for forming a monochrome image and a color image, and an image forming apparatus equipped with the exposure apparatus.

[0002]

2. Description of the Related Art Conventionally, many image forming apparatuses such as printers, facsimile machines, digital copiers and the like use an electrophotographic system, in which an image signal output from an external computer or an image reading system is included. An exposure system using a light source in which light emitting elements such as light emitting diodes are arrayed has been used as an exposure system for forming a latent image corresponding to an image on a photosensitive member. The exposure apparatus is small and can easily constitute a quiet image forming apparatus.

[0003] Here, the light emitting element is composed of a light emitting diode or the like, which emits diffused light from a certain point or a certain surface. It is necessary to form an image of the diffused light emitted from the light emitting element on each minute spot. Therefore, an exposure apparatus using many light emitting element rows is provided with a rod lens array as an image forming means to form a good spot. For this reason, the relative positional relationship between the light emitting element and the imaging element is made to have high positional accuracy.

On the other hand, there is a demand for a high-speed and high-definition image to be formed in an image forming apparatus itself.

[0005]

However, when the rod lens array as described above is used as an image forming means, the amount of light transmitted by a single row of rod lenses is low, and the latent image is formed on the image carrier by forming an array of several rows. In many cases, the required light amount for forming is achieved. The image forming means in which the rod lenses are arranged in several rows becomes very expensive. When high-speed image formation is performed, the light amount may be insufficient.

Further, since the required amount of light is achieved by superimposing images by individual rod lenses,
Sufficient positional accuracy is required between the individual elements so as to achieve high-accuracy image superposition, and a sophisticated adjustment mechanism and high accuracy of the element alone are required.

Therefore, in the present invention, it is possible to obtain a good image by a simple means in an exposure apparatus in which light emitting elements are arrayed, and to perform high-definition and high-speed image formation in an image forming apparatus using the exposure apparatus. With the goal. Also,
At the same time, the cost of the light emitting element chip on which the light emitting element is formed is also reduced.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an exposure apparatus according to the present invention comprises a plurality of light-emitting element arrays in which a plurality of light-emitting elements are arranged in a staggered manner on a plane in two or more stages to form a light-emitting element array group. And an image forming means for forming a light beam from the light emitting element array on the image carrier.Each of the light emitting element arrays includes an electrode for controlling each light emitting element. The electrodes are formed on the light emitting element chip provided, the electrodes are located at the ends in the light emitting element arrangement direction on the light emitting element chip, and wires for applying a voltage or a current are connected to the electrodes. Wherein the imaging means comprises a lens group corresponding to each light emitting element row in a 1: 1 relationship, and each lens of the lens group is configured not to form an image of the electrode and the wiring. In addition, light beams from each light emitting element array are imaged. And controlling the emission timing for each light-emitting element array according to the distance on the carrier.

In each light emitting element chip, a large number of light emitting thyristors capable of electrically controlling a threshold voltage or a threshold current are arranged as light emitting elements, and adjacent light emitting thyristors are mutually connected in one direction of voltage or current. A driving unit is formed by connecting with electric elements having a property, and each light emitting element row in one light emitting element chip shares this driving unit,
Light emission of a plurality of light emitting element arrays may be scanned by a two-phase transfer clock.

Further, the lens group as the image forming means may form a light beam from the light emitting element array at substantially the same magnification.

Alternatively, the lens group as the image forming means may form an image by reducing or enlarging a light beam from the light emitting element array.

[0012] In each lens forming a lens group as an image forming means, at least one of the surfaces of the lens may be constituted by a spherical surface or an aspherical surface.

In each lens forming a lens group as an image forming means, at least one of the surfaces of the lens may be formed in a Fresnel lens shape.

Each lens forming a lens group as an image forming element is formed by forming at least one of the surfaces of the lens into a binary lens shape having a plurality of stepped convex surfaces on the surface. Is also good.

Further, a part or the whole of the lens group may be integrally formed of glass or a plastic material.

Further, the image forming apparatus of the present invention forms an electrophotographic image by forming a light beam emitted from a light source by an image forming means and exposing the formed light beam on an image carrier. An image forming apparatus of the formula, wherein the exposure apparatus of the present invention is provided as the light source, and the exposure apparatus is arranged such that an arrangement direction of the light emitting element rows is a direction orthogonal to a rotation direction of the image carrier. It is characterized by the following.

[0017]

In the exposure apparatus of the present invention, a high-speed latent image can be formed by using an imaging element having a large transmitted light amount.
Further, since the configuration is such that optical crosstalk of each imaging element is prevented, a high-definition latent image can be formed. Further, in an image forming apparatus using the present exposure apparatus, high-speed image formation and high-definition image formation can be performed. Further, cost reduction of the light emitting element chip can be achieved at the same time.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on specific examples.

[0019]

<Embodiment 1> A first embodiment of an exposure apparatus and an image forming apparatus according to the present invention will be described with reference to FIGS.

First, a method for arranging light emitting element arrays according to the present invention will be described with reference to FIG.

In FIG. 1, CH11, CH12, CH1
3, CH14 is a light emitting element chip on which a light emitting element array is formed, and CH21, CH22, and CH23 are light emitting element chips on which a light emitting element array is formed. Also, CH1
The light-emitting element chip group consisting of CH1, CH12, CH13, and CH14 is arranged at a certain distance from the light-emitting element chip group consisting of CH21, CH22, and CH23, and is arranged in a staggered pattern as shown in the figure. L1 is the length of the light emitting element row,
P is the distance between the light emitting elements in the light emitting element row, CH11
The light emitting element chips CH11 and CH21 are positioned so that the distance in the light emitting element array direction between the light emitting element S11e at the end of the light emitting element and the light emitting element S21b at the end on the CH11 side of CH21 is also the same. Similarly, the other light-emitting element chips also have CH
11 and CH21 are positioned so as to have the same positional relationship.

At both ends of each light emitting element chip, electrodes T for applying a voltage for controlling the light emitting element are provided on each chip.
Each one is provided. The electrodes T are connected by wires W to the patterns LN on the substrate on which the light emitting element chips are mounted. The pattern LN is connected to a driver chip (not shown) for driving the light emitting element chip.

By arranging such electrodes at the ends of the chip, the light emitting element chip of this embodiment has a sufficient distance from the light emitting element on the side of the end to the chip end face. High-precision positioning at the time of cutting is not required, and cutting can be performed easily. Further, the width of the light emitting element chip can be made smaller in the width direction than in a configuration in which the electrodes are provided in the width direction of the light emitting element chip. As a result, the number of chips that can be cut out from one wafer can be increased, so that cost reduction can be realized. . The driving of the light emitting element will be described later. Here, the entire exposure apparatus 30 will be described with reference to FIGS.

FIG. 2 is a sectional view of the exposure device 30 and the photosensitive drum 2 which is an image carrier on which a light beam from the exposure device 30 is formed to form a latent image. In FIG. 2, CH12, CH
21 is a light emitting element chip and 50 is a driver chip. Reference numeral 4 denotes a common substrate on which the CH12, CH21 and other light emitting element chips, the driver chip 50, and other driver chips are mounted in common. Reference numeral 5 denotes a member having a heat dissipation function to which the common substrate 4 is fixed by bonding or screwing. Reference numeral 6 denotes a cover member formed of a material that does not substantially transmit at least the wavelength of a light beam from each light emitting element. Reference numeral 3 denotes a lens that forms a light beam from the light emitting element chip on a photosensitive drum serving as an image carrier. Are integrated with each other, and each light emitting element chip is provided with an independent lens unit. In other words, the lens portion for imaging the light beam from the light emitting element chip CH12 is 3c, and the light emitting element chip CH21
3b is a lens unit that forms an image of a light beam from the lens. For this reason, as shown in FIG. 3, the lens array 3 also has lens portions arranged in a zigzag pattern corresponding to each light emitting element chip.

Here, the image forming state of the lens array 3 will be described with reference to FIG.

FIG. 4 is a cross-sectional view of a part of the exposure apparatus in the arrangement direction of light emitting element chips. Here, a cross section on the light emitting element chips CH11 and CH12 side is shown. CH21, C
H22,. . . The cross section on the side is also equivalent.

In FIG. 4, CH11 and CH12 are light emitting element chips, 4 is a common mounting board, and 3 is a lens array. Reference numeral 3a denotes a lens unit that forms an image of a light beam from each light emitting element on the light emitting element chip CH11, and 3c denotes a lens unit that forms an image of the light beam from each light emitting element on the light emitting element chip CH12. 2a is the surface of the photosensitive drum 2. Here, the lens portions 3a and 3c are formed of a single lens having a biconvex surface.

Here, the light-emitting element array of the light-emitting element chip CH11 will be described. As described in FIG. 1, the light-emitting element array on the light-emitting element chip CH11 has a length of L1. Here, the lens portions 3a and 3c are located between a predetermined light emitting element chip and the photosensitive drum surface 2a, and are designed and positioned so as to form a light flux from the light emitting element chip at approximately equal magnification. Therefore, as shown in FIG. 4, the light emitting element chip C is formed on the photosensitive drum surface 2a.
The irradiation range of H11 is also L1, and similarly, the irradiation range of light emitting element chip CH21 is also L1.

Further, the light emitting element chips CH11 and CH12 and the light emitting element chip C are arranged in the positional relationship described with reference to FIG.
By arranging H21 and forming an image of the light-emitting element array on the light-emitting element chip CH21 by the same lens unit as shown in FIG.
12 is L1 + 2 × P during the irradiation range by 12, and L1 at the center in FIG. 4 is the irradiation range by the light emitting element chip CH21.

Similarly, the other light emitting element chips have the same structure as shown in FIGS.
An image from each light emitting element chip can be formed on the top without any gap in the light emitting element arrangement direction.

Although the lens diameter of each of the lenses 3a and 3c in the light emitting element arrangement direction in FIG. 4 is sufficiently larger than the light emitting element row length L1, the light emission side so as not to form an image of the electrode T and the wire W. Lens diameter L2 and aperture sections 3α, 3
β is composed. Such a configuration can prevent flare light from electrodes and wires that should not be imaged. In addition, the structure is such that light beams from light emitting element chips other than the light emitting element chip corresponding to a certain lens are hard to enter, and optical crosstalk can be prevented. Further, these lens groups can transmit a higher amount of light than a conventional rod lens, and as a result, can form a latent image at a higher speed.

Here, referring to FIG. 5, FIG. 6, and FIG. 7, a method for controlling the timing of the light flux from each light emitting element chip in a staggered arrangement and using the present exposure apparatus as a single light emitting element row will be described. explain.

FIG. 5 schematically shows an image forming state on the surface of the photosensitive drum when the light emitting element chip rows shown in FIG. 1 emit light simultaneously. Here, each circle indicates an image formed with respect to a light beam from each light emitting element. FIG. 6 shows an image forming state on the surface of the photosensitive drum when the timing control is performed. FIG. 7 is an enlarged view of the cross section of the exposure device 30 and the photosensitive drum 2 shown in FIG. The arc-shaped distance D in FIG. 7 is the distance on the photosensitive drum surface 2a at which each of the light-emitting element chip rows arranged in a staggered pattern is formed, and the same applies to D in FIG.

The timing control will be described.
First, the light emitting element chips (CH21, CH22, CH2) on the column side represented by the light emitting element chip CH21 in FIG.
3. . . ) To emit light. Then, the photosensitive drum 2 in FIG.
Since the imaging point is located at the position A on the position a, a latent image is formed at the position A. The photosensitive drum is rotated in the direction of the arrow in the drawing. Assuming that the peripheral speed of the photosensitive drum on the photosensitive drum surface 2a is v, the latent image formation position by CH21 after the time t = D / v from the latent image formation by CH21. Position B is reached. Therefore, the light emitting element chips on the column side (CH11, CH12, CH
13, CH14. . . ) To emit light. By controlling the light emission timing in each light emitting element chip row in this manner, the latent image formation similar to the latent image formation by one light emitting element chip row as shown in FIG. Can be performed. When attention is paid to the light emitting elements on the end side of each light emitting element chip as shown in FIG. 1, the light emitting elements adjacent to the light emitting element chips CH21 and CH12 are S21e and S12b, respectively, but as shown in FIG. On the drum surface, that is, in the image forming state, each lens portion is formed in a single lens shape, and since it is an inverted system, the light emitting element images which are close to the image of CH21 and the image of CH12 are the image of S21b and the image of S12e. . The same applies to the relationship between the entity of the other light emitting element chip and the image.

As shown in FIG. 8, the exposure device 30 is incorporated in an image forming apparatus as an exposure device.

Here, the operation will be described with reference to FIG. 8 taking a copying machine as an example of an image forming apparatus in which the exposure apparatus of the present embodiment is incorporated.

A document placed on the document table 24 is read by the reading system 90 and converted into image data. On the other hand, the recording material 80 is fed to the feeding rollers 13 and 14 in the main body.
Alternatively, the recording material 80 is fed from the outside of the main body via the feeding roller 15, and when it reaches the position of the registration rollers 16a and 16b, the position of the leading end of the recording material 80 is detected by a sensor (not shown). 16b. On the other hand, in accordance with the image data, charging is performed by the charger 17 in advance according to the image data, and the photosensitive drum 2 which is an image carrier rotated in the direction of the arrow in the drawing is exposed to form an electrostatic latent image. . A developer (not shown) is applied to the image carrier 2 from the developing device 18 in accordance with the electrostatic latent image. Then, at the same time as the photosensitive drum 2 to which the developing material is applied is rotated to a position on the transfer device 19, the recording material 80 also reaches the transfer device 19, and the developing material is transferred to the recording material 8.
The image data is transferred onto the “0” by the transfer device 19. As a result, the recording material 80 reaches the fixing devices 22a and 22b through the transport path 21, and the transferred developer is fixed to the recording material 80.
The sheet is discharged to the tray 23 to complete the image formation.

The light emitting element array in this embodiment is a light emitting thyristor array having a self-scanning shift register section, which will be described with reference to FIG.

FIG. 9 shows an equivalent circuit of one self-scanning light-emitting chip having a thyristor structure according to this embodiment. The operation principle and control of the light emitting element array will be described below.

FIG. 9 shows the inside of one light emitting element chip, but the other light emitting element chips have exactly the same configuration.
Here, 2001 indicates a shift register unit, and 2002 indicates a light emitting unit.

One row of light emitting elements is provided in this light emitting element chip, and each light emitting element row in the light emitting section 2002 has, for example, 128 light emitting thyristors. The number of light emitting thyristors may be two or more. Here, L1001, L1002, ..., L1128 are light emitting thyristors. Also, R1001, R1002, ...
R1128 is a load resistance, D1001, D1002,...
D1127 is a diode, T1001, T1002,...
.., T1128 denotes a switch element formed of a light emitting thyristor. VGA is a power supply line, φS is a start pulse line, and DATA is a write signal line to the light emitting thyristor of the light emitting element array. In order to apply these five signals, five electrodes are provided on each light emitting element chip as described with reference to FIG.

Here, for example, T1001 and T100
The gate terminal of the second switch element is a diode D1001.
Are connected to each other via a load resistor R1.
001 and R1002 are connected to the power supply VGA. On the other hand, transfer clocks φ1, φ
2 are applied to the respective cathodes of T1001 and T1002, respectively.

Here, the light emitting operation of the light emitting element array will be described.

At a certain time, if one of the switch elements T1001 is turned on by the transfer clock φ1, the gate potential thereof becomes almost zero volt, and this potential affects rightward through the diode D1001. After a certain time has elapsed, the next transfer clock φ
Only the elements in the right direction are selectively turned on by the transfer clock φ2 which is 180 degrees out of phase with 1, so that the transfer in the right direction is possible. From the start of the ON state by φ1 to the turn-on of the rightward element by φ2,
T1001 is addressed, during which a DATA clock corresponding to the image information is applied and a pulse is applied from the write signal line DATA, thereby causing the corresponding light emitting thyristor L
1001 emits light. Depending on the image signal given here, each light emitting element can be turned off. After the turn-on by φ2, L1002 can emit light because T1002 is addressed. By synchronizing such a transfer operation with ON / OFF of the write signal and repeating this, a predetermined light-emitting thyristor can emit light in accordance with image data.

Although the above description has been made on the driving of one light emitting element chip, the same applies to the other light emitting element chips. Therefore, since signals other than DATA can be common to each light emitting element chip, the driver section can be common to each light emitting element chip.

Further, a Fresnel lens may be used for the lens portion of the lens group. Here, the Fresnel lens array will be described with reference to FIG.

FIG. 10 is a cross-sectional view of a part of the exposure apparatus in the light emitting element chip arrangement direction. Here, a cross section of the light emitting element chips CH412 and CH413 is shown. The same applies to the light emitting element chip rows on the other side of the staggered arrangement.

In FIG. 10, CH412, CH413
Denotes a light emitting element chip, 404 denotes a common mounting substrate, and 403 denotes a Fresnel lens array. Reference numeral 403c denotes a lens unit that forms an image of a light beam from each light emitting element on the light emitting element chip CH412, and 403e denotes a lens unit that forms an image of a light beam from each light emitting element on the light emitting element chip CH413. Also, 402
a is the surface of the photosensitive drum. Here, the lens unit 403c,
Reference numeral 403e denotes a Fresnel lens obtained by dividing a biconvex single lens on a concentric circle to form a Fresnel lens. The configuration in which no image is formed on the electrode T and the wire W is the same as in the above-described spherical lens system.

By configuring the lens portion as a Fresnel lens in this manner, a lens having a larger curvature can be configured as a lens having a smaller thickness, and as a result, it contributes to miniaturization of the exposure apparatus and, consequently, the image forming apparatus. .

Further, a binary lens having a plurality of steps of a convex surface on the surface of the lens portion of the lens array may be used. This binary lens array will be described with reference to FIG.

FIG. 11 is a sectional view of a part of the exposure apparatus in the arrangement direction of the light emitting element chips. Here, a cross section on the light emitting element chips CH512 and CH513 side is shown. The same applies to the light emitting element chip rows on the other side of the staggered arrangement.

In FIG. 11, CH512, CH513
Is a light emitting element chip, 504 is a common mounting substrate, and 50
3 is a binary lens array. A lens unit 503c forms an image of a light beam from each light emitting element on the light emitting element chip CH512, and a lens unit 503e forms an image of a light beam from each light emitting element on the light emitting element chip CH513. Also,
502a is a photosensitive drum surface. Here, the lens unit 50
Reference numerals 3c and 503e denote a binary lens in which a single lens having a convex surface on one side and a flat surface on one side is divided concentrically into a binary lens. Here, the convex side is the object side,
That is, it is provided on the light emitting element side. The configuration in which no image is formed on the electrode T and the wire W is the same as in the above-described spherical lens system.

By configuring the lens portion as a binary lens in this manner, a lens having a larger curvature can be configured as a lens having a smaller thickness, and as a result, it contributes to the miniaturization of the exposure apparatus and, consequently, the image forming apparatus. At the same time, since the binary lens can be manufactured in the same manner as the process of the LSI or the like, mass production becomes easy.

As described above, in the exposure apparatus according to the present embodiment, a high-speed latent image is formed by increasing the transmission efficiency of the lens serving as the image forming element, and the influence on the image formation of the electrode portion and the wire is obtained. Is removed, and optical crosstalk by each lens is small, so that a latent image of a high-definition image can be formed. Therefore, by applying the present exposure apparatus to an image forming apparatus, high-speed and high-quality image output can be performed. In addition, cost reduction can be realized by arranging the electrode portion at the end of the light emitting element chip in the light emitting element arrangement direction.

<Embodiment 2> A second embodiment of the exposure apparatus and the image forming apparatus of the present invention will be described below with reference to FIGS. This embodiment is an embodiment in which a lens system as an imaging element is configured as a reduction system.

Here, the method of driving the light emitting element array of the exposure apparatus of the present embodiment and the image forming apparatus in which the exposure apparatus is installed are the same as those of the first embodiment, and therefore the description thereof will be omitted.

First, a method for arranging light emitting element arrays according to the present invention will be described with reference to FIG.

In FIG. 12, CH311, CH312,
CH313 and CH314 are light-emitting element chips on which light-emitting element rows are formed, and CH321, CH322, and CH32
Reference numeral 3 denotes a light emitting element chip on which a light emitting element array is formed. In addition, CH311, CH312, CH
The light emitting element chip group composed of CH 313 and CH 314 is CH
321, CH 322, CH 323, and CH 324 are arranged in a staggered pattern as shown in FIG. L3 is the length of the light emitting element row. The light emitting elements S311e at the end of CH311 and C
The position of the end of H321 on the CH311 side with respect to the light emitting element S321b is positioned such that the distance in the light emitting element row arrangement direction overlaps by the distance L4. Similarly, the other light emitting element chips are positioned so as to have the same positional relationship as CH311 and CH321. Further, as in the first embodiment, the element pitch of the light emitting elements is P.

As in the first embodiment, five electrodes T for applying a voltage for controlling the light emitting element are provided at each end of each light emitting element chip. The wiring T is connected from the electrode T to the pattern LN on the substrate on which each light emitting element chip is mounted. The pattern LN is connected to a driver chip (not shown) for driving the light emitting element chip. The effects of these are the same as those in the first embodiment, and thus will not be described.

Further, the configuration of the entire exposure apparatus is the same as that of the first embodiment, and the description is omitted.

Here, the image forming state of the lens array will be described with reference to FIG.

FIG. 13 is a cross-sectional view of a part of the exposure apparatus in the light emitting element chip arrangement direction. Here, a cross section on the light emitting element chips CH312 and CH313 side is shown. CH
321, CH322,. . . The cross section on the side is also equivalent.

In FIG. 13, CH312, CH313
Is a light emitting element chip, 304 is a common mounting substrate and 303
Is a lens array. 303c is a light emitting element chip CH
A lens unit that forms an image of a light beam from each light emitting element on 312;
Reference numeral 303e denotes a lens unit that forms an image of a light beam from each light emitting element on the light emitting element chip CH313. Reference numeral 302a denotes a photosensitive drum surface. Here, the lens units 303c and 30
Reference numeral 3e denotes a biconvex single lens.

The light emitting element array of the light emitting element chip CH312 will be described. As described in FIG. 12, the light emitting element array on the light emitting element chip CH312 has a length of L3. Here, the lens portions 303c and 303e are located between a predetermined light emitting element chip and the photosensitive drum surface 302a, and are designed and positioned so as to reduce and form a light beam from the light emitting element chip. This reduces the object having the length of L3 to L3 ″ as shown in FIG. 13. P ″ is the length when the element pitch P is imaged at the same reduction magnification.

Here, as shown in FIG. 13, in order to use overlapping light-emitting element rows in a staggered arrangement as in the first embodiment, timing control is performed to use them as one light-emitting element row with an equal pixel pitch. As shown in FIG. 13, the range between the irradiation range L3 ″ by the light emitting element chip CH312 and the irradiation range L3 ″ by the light emitting element chip CH313, that is, the irradiation range by the light emitting element chip CH322 is L3 ″ + 2 × P ″ at the same time. It must be. When the imaging magnification for satisfying this is obtained, considering that the distance between the light emitting elements at the end of each light emitting element chip is equivalent to the light emitting element interval on the light emitting element chip in the image forming state, the object side, that is, the actual When the light emitting element interval on the light emitting element chip on the side is P and the imaging magnification is β, β = L3 ″ / L3 = (L3-L4-P) / (L3-P) (β <1).

As described above, by using the reduction lens together with the light emitting element rows in a staggered arrangement, a latent image can be formed with a higher definition than the pixel pitch of the light emitting element rows.

Since the description of the timing control is the same as that of the first embodiment, the description is omitted.

Similarly, for the other light emitting element chips, images from the respective light emitting element chips are formed on the photosensitive drum surface 302a without any gap in the light emitting element arrangement direction by the configuration shown in FIGS. be able to.

Further, each lens 303c in FIG.
Although the lens diameter of 303e in the light emitting element arrangement direction is sufficiently larger than the light emitting element row length L3, the exit side lens diameter L5 and the stop portions 303α and 303β are configured so as not to form an image of the electrode T and the wire W. Have been. Such a configuration can prevent flare light from electrodes and wires that should not be imaged. In addition, the structure is such that light beams from light emitting element chips other than the light emitting element chip corresponding to a certain lens are hard to enter, and optical crosstalk can be prevented. Further, these lens groups can transmit a higher amount of light than a conventional rod lens, and as a result, can form a latent image at a higher speed.

As described above, in the exposure apparatus of this embodiment, in addition to the effects of the first embodiment, the use of the reduction system lens enables the formation of a latent image with higher definition than the light emitting element interval. Therefore, by applying the present exposure apparatus to an image forming apparatus, it is possible to output a high-quality image at high speed.

In this embodiment, the imaging system is a reduction system. However, this is also effective as an enlargement system. In this case, in FIG. 13, the distance between the light emitting element rows is set to L4 by reversing the overlap of L4, and the light emitting element rows are enlarged and imaged to reduce the size of the light emitting element chip with respect to the latent image range. As a result, the cost of the light emitting element chip can be reduced.

[0072]

As described above, in the exposure apparatus according to the present invention, a high-speed latent image can be formed by using an imaging element having a large amount of transmitted light, and an image of electrodes and wires on a light emitting element chip can be formed. , Optical crosstalk of each imaging element can be prevented, and a high-definition latent image can be formed. Further, by using the present exposure apparatus for an image forming apparatus, an image forming apparatus that provides high-speed and high-definition images can be provided. Further, cost reduction can be realized by disposing the electrode portion on the light emitting element chip at the end of the light emitting element chip in the light emitting element arrangement direction.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an arrangement of light emitting element chips according to a first embodiment of the present invention.

FIG. 2 is a sectional view of an exposure apparatus and a photosensitive drum according to the first embodiment of the present invention.

FIG. 3 is an external view of a lens array according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating an image forming state according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating an image forming state on a photosensitive drum when timing control according to the first embodiment of the present invention is not performed.

FIG. 6 is a diagram illustrating an image forming state on a photosensitive drum after timing control according to the first embodiment of the present invention.

FIG. 7 is a diagram illustrating an interval for performing timing control according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating an example of an image forming apparatus into which the exposure apparatus according to the first embodiment of the present invention is incorporated.

FIG. 9 is an example of an equivalent circuit in the light emitting element chip according to the first embodiment of the present invention.

FIG. 10 is a diagram illustrating an image forming state by the Fresnel lens array according to the first embodiment of the present invention.

FIG. 11 is a diagram illustrating an image forming state by the binary lens array according to the first embodiment of the present invention.

FIG. 12 is a diagram illustrating an arrangement of light emitting element chips according to a second embodiment of the present invention.

FIG. 13 is a diagram illustrating an image forming state according to the second embodiment of the present invention.

[Explanation of symbols]

2, 302, 402, 502 Photosensitive drum 3, 303, 403, 503 Lens array CH11, CH12, CH13, CH14, CH21,
CH22, CH23, CH311, CH312, CH3
13, CH314, CH321, CH322, CH32
3, CH324 light emitting element chip T electrode W wire β imaging magnification

Claims (9)

[Claims] 1. A light emitting element array in which a plurality of light emitting elements are arranged in a staggered manner in two or more stages on a plane to form a light emitting element array group, and a light beam from the light emitting element array group is image-bearing. An exposure apparatus comprising: an image forming means for forming an image on a body, wherein each light emitting element array is formed on a light emitting element chip having electrodes for controlling each light emitting element, and the electrodes emit light. The electrode is connected to an end of the light emitting element arrangement direction on the element chip, and a wiring for applying a voltage or a current is connected to the electrode. : An image carrier on which each lens of the lens group is formed so as not to form an image of the electrode and the wiring, and a light beam from each light emitting element array is formed. Light emitting tie for each light emitting element row according to the above distance An exposure apparatus characterized in that the exposure is controlled. 2. Each light emitting element chip is provided with a plurality of light emitting thyristors capable of electrically controlling a threshold voltage or a threshold current as light emitting elements, and adjacent light emitting thyristors are arranged in one direction of voltage or current. A drive unit is formed by connecting the light emitting element rows in one light emitting element chip, and the light emission of the plurality of light emitting element rows is scanned by a two-phase transfer clock. The exposure apparatus according to claim 1, wherein the exposure is performed. 3. The exposure apparatus according to claim 1, wherein the lens group serving as an image forming unit forms an image of a light beam from the light emitting element array at substantially the same magnification. 4. The exposure apparatus according to claim 1, wherein the lens group serving as an image forming unit forms an image by reducing or enlarging a light beam from the light emitting element array. 5. The lens according to claim 1, wherein each of the lenses forming the lens group serving as the image forming means has at least one of the surfaces of the lens formed of a spherical surface or an aspherical surface. An exposure apparatus according to any one of the above. 6. An individual lens forming a lens group as an image forming means, wherein at least one of the surfaces of the lens is formed in a Fresnel lens shape.
The exposure apparatus according to any one of claims 1 to 5, 7. An individual lens forming a lens group as an image forming means is formed in a binary lens shape in which at least one of the surfaces of the lens has a plurality of steps of convex surface on the surface. The exposure apparatus according to claim 1, wherein: 8. The exposure apparatus according to claim 1, wherein a part or the whole of the lens group is integrally formed of glass or a plastic material. 9. An electrophotographic image forming apparatus which forms a light beam emitted from a light source by an image forming means and exposes the formed light beam on an image carrier to visualize the light beam. An exposure apparatus according to any one of claims 1 to 8, which is provided as the light source, and the exposure apparatus is arranged such that an arrangement direction of the light emitting element rows is a direction orthogonal to a rotation direction of the image carrier. An image forming apparatus comprising: