JP2007296680A - Light emitting device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the yield of a light emitting device which has a plurality of light emitting elements on a surface of a substrate. <P>SOLUTION: The light emitting device H has a plurality of unit sections U (U1, U2) which are arranged side by side in an X direction. Each of the unit sections U is formed of a substrate 10 which is different from each other, the plurality of light emitting elements E arranged on the surface of the substrate along the X direction, and IC chips 15 for driving the light emitting elements of the corresponding unit section U. The unit sections U are secured to a single support body 20 which is opposed to the substrates 10 in a manner pinching the light emitting elements E of the unit sections U. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a light emitting device in which a plurality of light emitting elements are arranged, and an image forming apparatus using the same.

Conventionally, light-emitting devices in which various light-emitting elements such as organic light-emitting diode elements are arranged on the surface of a substrate have been proposed. For example, Patent Document 1 discloses an electrophotographic image forming apparatus that employs a light emitting device as means for exposing an image carrier such as a photosensitive drum. The light emitting device of Patent Document 1 includes a long substrate arranged in a posture having the main scanning direction as a longitudinal direction, a number of light emitting elements arranged on the surface of the substrate along the main scanning direction, and the surface of the substrate. And an integrated circuit for driving each light emitting element.
JP 2006-51703 A (FIG. 2)

However, it is difficult to form a large number of light-emitting elements having desired characteristics on the surface of a single substrate for reasons of manufacturing technology. In a light emitting device in which a light emitting element is miniaturized for high definition of an image, a defect (for example, non-lighting) of the light emitting element is particularly likely to occur. For example, when any of the light emitting elements is not lit in the light emitting device employed in the image forming apparatus, streaky unevenness in the sub-scanning direction is present at a position corresponding to the light emitting element in the actually formed image. appear. In addition, since it is practically impossible to repair a defective light emitting element, the light emitting device is determined to be defective during the inspection process even when the defect is only one light emitting element. . Therefore, the conventional light emitting device has a problem that the yield is low. In view of the above circumstances, an object of the present invention is to solve the problem of improving the yield of a light emitting device in which a plurality of light emitting elements are formed on a surface of a substrate.

In order to solve the above problems, a light-emitting device according to the present invention includes a plurality of unit portions arranged in a predetermined direction, and each of the plurality of unit portions is a separate substrate for each unit portion; A plurality of light emitting elements arranged on a surface of the substrate along a predetermined direction. In other words, the plurality of light-emitting elements included in the light-emitting device are arranged in a distributed manner on a plurality of separate substrates. In this configuration, for example, if any one of the plurality of unit parts is determined to be defective, the remaining unit part can be used as it is if the unit part is replaced with a non-defective unit part. . Therefore, the yield of the light emitting device can be improved as compared with the conventional configuration in which all the light emitting elements are formed on a single substrate.

In addition, a configuration in which each of the plurality of unit units includes a drive circuit that drives the plurality of light emitting elements of the unit unit is also employed. According to this configuration, when a defect is found in the drive circuit of one unit unit, the remaining unit unit can be used as it is for the production of the light emitting device if the unit unit is replaced with another unit unit. There is. Note that the driving circuit may be mounted in the form of an IC chip or may be formed of a thin film transistor formed on the surface of the substrate.

In a preferred aspect of the present invention, a single support body to which a plurality of unit portions are fixed is provided, and the support body faces each substrate with each light emitting element of the plurality of unit portions interposed therebetween. According to the above aspect, the substrate of each unit portion is supported by the common support, and the light emitting element of each unit portion is protected by the gap between the support and the substrate. Therefore, the configuration of the light emitting device can be simplified as compared with the configuration in which the member that supports each substrate and the member that protects each light emitting element are separately arranged. Instead of the configuration in which each substrate is fixed to the support as described above (or with this configuration)
A configuration in which end surfaces of adjacent substrates are bonded to each other is also preferably employed.

The support according to the above aspect includes, for example, a plate-like portion facing each substrate of a plurality of unit portions, and a side wall portion protruding from the plate-like portion toward each substrate and having an end surface bonded to each substrate. . Each light emitting element of the plurality of unit parts in this aspect is sealed in a space surrounded by the side wall part in the gap between the substrate and the plate-like part. According to the above aspect, it is possible to prevent the external air and moisture from adhering to each light emitting element and to suppress each deterioration.

In a further preferred aspect, the side wall portion is a portion interposed in a gap between the plurality of light emitting elements of each unit portion and the plurality of light emitting elements of other unit portions adjacent to the unit portion (for example, the portion of FIGS. 2 and 3). 22
3). That is, each light emitting element is sealed in a space partitioned for each unit. According to this aspect, each light emitting element can be reliably sealed.

In a preferred aspect of the present invention, each of the plurality of unit parts has the same structure. According to this aspect, since the light emitting device is manufactured by combining a plurality of unit parts without distinguishing the plurality of unit parts, the manufacturing efficiency and yield of the light emitting device are reduced as compared with the configuration in which the structure of each unit part is different. It is possible to improve. Note that “the unit portions have the same structure” includes not only the case where the physical structures are completely the same, but also the case where the structures are substantially the same. The structure of the plurality of unit parts is “substantially the same” means, for example, a relationship in which the function and function of the light emitting device do not change even if one unit part is replaced with another unit part. . Therefore, for example, when the number of light emitting elements and the pattern of the array are common over a plurality of unit parts, and the plurality of unit parts are line symmetric with respect to the direction of each array and the axis in the direction perpendicular thereto, It can be said that each unit part has the same structure. Note that even though each of the plurality of unit portions has the same structure, it is not necessary until all the unit portions constituting the light emitting device have the same structure.

The light emitting device according to the present invention is used in various electronic devices. A typical example of this electronic apparatus is an image forming apparatus using the light emitting device of the present invention as an exposure device (exposure head). The image forming apparatus of the present invention is an image carrier (for example, the photosensitive drum 70 in FIG. 1) on which a latent image is formed by exposure.
And a light emitting device of the present invention that exposes the image carrier, and a developing unit that forms a visible image by adding a developer to the latent image formed on the image carrier. According to the light emitting device of the present invention, the yield can be improved. Therefore, according to the image forming apparatus equipped with the light emitting device, the manufacturing cost can be reduced.

In the image forming apparatus according to one aspect, the image carrier includes an image forming surface that proceeds in the sub-scanning direction, and the light-emitting device is arranged such that a plurality of unit portions are arranged in the main scanning direction. In an image forming apparatus in which a plurality of light emitting elements are arranged in the main scanning direction as in this aspect, when any of the light emitting elements is defective (for example, when not lit), the light emission of the actually formed image Streaky irregularities in the sub-scanning direction occur at positions corresponding to the elements. Therefore, if a plurality of light-emitting elements are formed on a single substrate, the light-emitting device as a whole must be determined as a defective product even if only one light-emitting element is defective. . The light-emitting device of the present invention that can use the other unit portion even when a defect is found in the light-emitting element of one unit portion is particularly suitable for an image forming apparatus in which a plurality of light-emitting elements are arranged in the main scanning direction. It can be said that there is.

The application of the light emitting device according to the present invention is not limited to the exposure of the image carrier. For example, in an image reading apparatus such as a scanner, the light emitting device according to the present invention can be used for illuminating a document. This image reading apparatus includes a light emitting device according to the present invention and a light receiving device (for example, a CCD (Charge Coupl) that converts light emitted from the light emitting device and reflected by a reading target (original) into an electrical signal.
ed Device). A light-emitting device in which a large number of light-emitting elements are arranged in a matrix is used as a display device for various electronic devices.

<A: Light emitting device>
FIG. 1 is a perspective view showing a partial structure of an image forming apparatus according to an embodiment of the present invention.
As shown in the figure, the image forming apparatus includes a light emitting device H, a converging lens array 30 and a photosensitive drum 70. The photosensitive drum 70 is supported by a rotation shaft extending in the X direction (main scanning direction), and rotates with the image forming surface 72 (outer peripheral surface) facing the light emitting device H.

The converging lens array 30 is disposed in the gap between the light emitting device H and the photosensitive drum 70, and forms an erect image of light emitted from the light emitting device H on the image forming surface 72 of the photosensitive drum 70. SLA (Selfoc Lens Array) available from Nippon Sheet Glass Co., Ltd. is suitably used as the converging lens array 30. “SELFOC / SELFOC” is a registered trademark of Nippon Sheet Glass Co., Ltd.

2 is a plan view showing the configuration of the light emitting device H as seen from the side opposite to the photosensitive drum 70 (upper side in FIG. 1), and FIG. 3 is a cross-sectional view taken along the line III-III in FIG. The light emitting device H
An exposure head for forming a latent image on the image forming surface 72 of the photosensitive drum 70 by irradiation of light, as shown in FIGS. 1 to 3, a support 20 and two unit portions U (U1 and U2) including. The two unit parts U1 and U2 are arranged in the X direction.

As shown in FIGS. 2 and 3, the unit portion U1 includes a substrate 10a, a plurality of light emitting elements E, and a plurality of IC chips 15. Similarly, the unit portion U2 includes a substrate 10b, a plurality of light emitting elements E, and a plurality of IC chips 15. Each substrate 10 (10a and 10b) is a light-transmitting flat plate formed into a rectangular shape with glass or plastic. The substrate 10a and the substrate 10b are separate bodies.
The end surface (side surface in the X direction) of the substrate 10a and the end surface of the substrate 10b are opposed to each other and bonded by an adhesive 25 filled therebetween.

As shown in FIGS. 2 and 3, the plurality of light emitting elements E and the plurality of IC chips 15 in the unit portion U1.
Is disposed on the surface of the substrate 10a opposite to the photosensitive drum 70. Similarly, the plurality of light emitting elements E and the plurality of IC chips 15 of the unit portion U2 are disposed on the surface of the substrate 10b. Each light emitting element E is an organic light emitting diode element in which a light emitting layer made of an organic EL (Electroluminescence) material is interposed in a gap between an anode and a cathode. As shown in FIG. 2, a large number of light emitting elements E belonging to each unit U are arranged in two rows and staggered along the X direction. However, the pattern of the arrangement of the light emitting elements E is arbitrary, and may be a single row, three or more rows, or another appropriate pattern.

The IC chips 15 of the unit unit U1 are arranged along the X direction on the surface of the substrate 10a to drive the light emitting elements E of the unit unit U1. Similarly, each IC chip 15 of the unit U2 is connected to the substrate 10b.
The light emitting elements E of the unit U2 are driven on the surface of the unit. Each IC chip 15 is COG (C
hip on Glass) technology. Light emitted from each light emitting element E passes through the substrate 10 and the converging lens array 30 and then reaches the image forming surface 72 of the photosensitive drum 70. While the image forming surface 72 is stepped in the sub-scanning direction, the light emitting elements E of the unit portions U1 and U2 are connected to the IC chip 15.
As a result, the desired latent image is formed on the image forming surface 72.

As described above, the unit U1 and the unit U2 have substantially the same configuration. That is,
The substrate 10a and the substrate 10b have the same shape, and the number and arrangement pattern of the light emitting elements E and the IC chips 15 are common to the unit portion U1 and the unit portion U2. Further, the configuration of each light emitting element E and each IC chip 15 is also common to the unit portion U1 and the unit portion U2. Each unit U is line symmetric with respect to an axis along each of the X direction and the Y direction. Therefore, the unit portion U1 in FIG.
Even if the unit U2 is replaced, the configuration and function of the light emitting device H do not change.

The support body 20 of FIGS. 1 to 3 is a single member molded (for example, injection molded) with various resin materials, for example. The support 20 of the present embodiment has a shape in which a plate-like portion 21 and a side wall portion 22 are integrally formed. The plate-like portion 21 is a substantially rectangular portion whose dimensions are selected so as to face the light emitting elements E of the unit portions U1 and U2 when viewed from the direction perpendicular to the substrate 10 (Z direction). The side wall portion 22 is a portion that protrudes from the surface of the plate-like portion 21 toward the substrate 10, and as shown in FIGS. 2 and 3, a portion 221 that forms a rectangular frame shape along the periphery of the plate-like portion 21. , And a portion 223 extending in the Y direction (sub-scanning direction) so as to connect the central portions of the long sides of the portion 221 to each other. That is, the part 223 is a part that partitions the space surrounded by the part 221.

The end surface (bottom surface) of the side wall portion 22 that faces each substrate 10 (10a, 10b) is bonded to each substrate 10 by an adhesive, for example. In other words, the substrates 10 a and 10 b are fixed to the support 20. As shown in FIG. 3, each light emitting element E of the unit portion U1 is in a space surrounded by the side wall portion 22 (part 221 / part 223) in the gap between the substrate 10a and the plate-like part 21 of the support 20. Sealed. Similarly, each light emitting element E of the unit portion U2 is sealed in a space surrounded by the side wall portion 22 in the gap between the substrate 10b and the plate-like portion 21. As described above, the support 2 of the present embodiment
0 has both a function of maintaining the substrates 10a and 10b in an intended posture and a function of blocking (sealing) the light-emitting elements E of the unit units U from the outside air. In the closed space where each light emitting element E is sealed, an inert gas or a desiccant is enclosed.

As described above, the light emitting device H of the present embodiment has a structure in which two unit portions U1 and U2 each including a plurality of light emitting elements E and a plurality of IC chips 15 are connected. In other words, a plurality of light-emitting elements E and a plurality of IC chips 15 included in the light-emitting device H are arranged in a unit part U1 and a unit part U2. Therefore, for example, the light emitting element E or the IC chip 1 of the unit portion U1.
If a defect is found in 5, the light emitting device H is created by replacing the unit U1 related to the defect with another unit U1 and combining it with the unit U2. In the conventional configuration in which all the light emitting elements E are formed on the single substrate 10, even if a defect is generated in one light emitting element E, the light emitting device H as a whole is determined to be defective. . On the other hand, in the present embodiment, even when the unit portion U1 is determined to be defective, the unit portion U2 having no defect can be continuously used for manufacturing the light emitting device H. Therefore, the yield of the light emitting device H can be significantly improved as compared with the conventional configuration.

Further, in the present embodiment, since the support 20 is used for supporting the substrates 10a and 10b and sealing each light emitting element E, a member that supports the substrates 10a and 10b and a member that seals each light emitting element E are used. There is an advantage that the configuration of the light emitting device H is simplified (for example, the number of parts is reduced) as compared with a configuration in which and are separately installed. Furthermore, since each light emitting element E of the unit portion U1 and each light emitting element E of the unit portion U2 are sealed by a single support 20, light emission is performed as compared with a configuration in which each is sealed by a separate member. The configuration of the device H is simplified.

By the way, if the unit U1 and the unit U2 are different in configuration, for example, in the case of mass production of the light emitting device H, there is a problem that the unit U2 becomes redundant when defects occur in the unit U1. Can do. When the unit U1 and the unit U2 have a common configuration as in the present embodiment, the element in which the light emitting element E and the IC chip 15 are arranged on the surface of the substrate 10 is set as any of the unit U1 and U2. Therefore, the situation where only one of the unit parts U1 and U2 becomes excessive is avoided. In addition, since the manufacturing process is made common between the unit part U1 and the unit part U2, the manufacturing cost of the light emitting device H is reduced as compared with the case where the unit part U1 and the unit part U2 have different configurations. There are also advantages. Furthermore, since a combination of a plurality of (two) unit portions U is arbitrary, for example, a plurality of unit portions U whose characteristics (for example, light emission efficiency) of the light emitting element E are approximated from among a large number of unit portions U that are mass-produced. It is also possible to manufacture the light emitting device H by selecting appropriately. Therefore, a high-quality light-emitting device H in which the characteristics of the respective light-emitting elements E are made uniform can be manufactured with a high yield.

<B: Modification>
Various modifications can be made to the above embodiment. An example of a specific modification is as follows. In addition, you may combine each following aspect suitably.

(1) Modification 1
The number of unit parts U constituting the light emitting device H is arbitrary. That is, as shown in FIG.
It is good also as a structure by which the unit part U (board | substrate 10) of the piece or more was connected. In addition, illustration of the support body 20 is abbreviate | omitted in FIG. As described above, the yield of the light emitting device H is improved as the total number of unit parts U is increased. Further, the number of light emitting elements E and IC chips 15 provided in one unit U is arbitrary. For example, a configuration in which only one IC chip 15 is mounted on the substrate 10 of each unit unit U is also employed.

(2) Modification 2
The shape of the support 20 is not limited to the above examples. For example, in the above embodiment, the configuration in which each light emitting element E of the unit portion U1 and each light emitting element E of the unit portion U2 are sealed in individual closed spaces partitioned by the portion 223 is exemplified. The portion 223 is omitted as shown in FIG.
It is good also as a structure where the area | region which seals each 1 * U2 light emitting element E continues. However, according to the configuration in which individual closed spaces are defined for each unit portion U as shown in FIG. 2, each light emitting element E can be reliably sealed as compared with the configuration in FIG. 5.

In the above embodiment, the configuration in which each light emitting element E of the unit portion U1 and each light emitting element E of the unit portion U2 are sealed by a single member (support 20) is described. A configuration in which a member that works to seal each light emitting element E is installed separately for each unit U is also adopted. The substrates 10a and 10b in this configuration may be bonded to each other only by the adhesive 25,
Each may be fixed to a single member prepared separately from the member for sealing each light emitting element E.

(3) Modification 3
In FIG. 2 to FIG. 5, for the sake of convenience, the intervals between the light emitting elements E adjacent to each other across the boundary of each substrate 10 are the same as each light emitting element adjacent on one substrate 10. E
The structure which is made wider than the interval is shown. However, if there is a difference in the interval between the light emitting elements E, the image formed by the image forming apparatus is uneven (particularly, stripe-like unevenness extending in the sub-scanning direction).
May occur. Therefore, in practice, each light emitting element E is arranged in the entire array (each substrate 1
Are arranged at equal intervals (same pitch).

For example, in the light-emitting device H in which the plurality of light-emitting elements E are arranged in two rows and staggered like each of the above embodiments, the configuration of FIG. 6 is adopted. FIG. 6 is an enlarged plan view showing a boundary portion between the substrate 10a and the substrate 10b in the light emitting device H according to one embodiment. As shown in part (a) of the figure, on the end surface of the substrate 10a facing the substrate 10b, two light emitting elements E belonging to the unit unit U1 are located at the end on the unit unit U2 side. Inclined surface 11 along light emitting element E
Is formed. Similarly, on the end surface of the substrate 10b facing the substrate 10a, the inclined surface 11 is formed along the two light emitting elements E located at the end of the unit portion U2 on the unit portion U1 side. As shown in part (b) of FIG. 6, the substrate 10a and the substrate 10b are joined so that the inclined surfaces 11 are in contact with each other. According to the above aspect, since all the light emitting elements E of the light emitting device H are arranged at equal intervals with high accuracy, it is possible to form a high-quality image with suppressed unevenness.

(4) Modification 4
In the above embodiment, the configuration in which the IC chip 15 is mounted on the substrate 10 is illustrated, but the arrangement of the circuits for driving the light emitting elements E is arbitrary. For example, the IC chip 15 may be mounted on a wiring substrate bonded to the substrate 10, or the driving circuit may be configured by a thin film transistor including a semiconductor layer formed of, for example, low-temperature polysilicon on the surface of the substrate 10. Good.

(5) Modification 5
An organic light emitting diode element is only an example of a light emitting element. For example, light-emitting elements and light-emitting diode elements including light-emitting layers made of inorganic EL materials, field emission (FE) elements, surface-conduction electron-emitter (SE) elements, ballistic electron emission (BS) The present invention can be applied to a light emitting device having various light emitting elements such as a ballistic electron surface emitting element.

<C: Application example>
Next, an image forming apparatus is illustrated as one form of equipment using the light emitting device according to the present invention.
FIG. 7 is a cross-sectional view showing a configuration of an image forming apparatus employing the light emitting device H according to each of the above embodiments. The image forming apparatus is a tandem type full-color image forming apparatus, and the four light emitting devices H (HK, HC, HM, HY) according to the above-described form and four photosensitive drums corresponding to the respective light emitting devices H. 70 (70K, 70C, 70M, 70Y). One light emitting device H is disposed so as to face the image forming surface 72 (outer peripheral surface) of the corresponding photosensitive drum 70. In addition,
The subscripts “K”, “C”, “M”, and “Y” of each symbol mean that they are used for forming each visible image of black (K), cyan (C), magenta (M), and yellow (Y). is doing. Further, in FIG. 7, illustration of the converging lens array 30 is omitted.

As shown in FIG. 7, an endless intermediate transfer belt 72 is wound around the driving roller 711 and the driven roller 712. The four photosensitive drums 70 are arranged around the intermediate transfer belt 72 at a predetermined interval from each other. Each photosensitive drum 70 rotates in synchronization with driving of the intermediate transfer belt 72.

In addition to the light emitting device H, a corona charger 731 (731K,
731C, 731M, 731Y) and developing unit 732 (732K, 732C, 732M, 732Y)
And are arranged. The corona charger 731 corresponds to the image forming surface 7 of the photosensitive drum 70 corresponding thereto.
2 is charged uniformly. Each of the light emitting devices H exposes this charged image forming surface 72 to form an electrostatic latent image. Each developing device 732 forms a visible image (visible image) on the photosensitive drum 70 by attaching a developer (toner) to the electrostatic latent image.

Each color (black, cyan, magenta, yellow) formed on the photosensitive drum 70 as described above.
Are sequentially transferred (primary transfer) to the surface of the intermediate transfer belt 72 to form a full-color visible image. Inside the intermediate transfer belt 72 are four primary transfer corotrons (transfer devices).
74 (74K, 74C, 74M, 74Y) are arranged. Each primary transfer corotron 74 electrostatically attracts a visible image from the corresponding photosensitive drum 70, thereby the photosensitive drum 7.
The visible image is transferred to the intermediate transfer belt 72 that passes through the gap between 0 and the primary transfer corotron 74.

The sheets (recording material) 75 are fed one by one from the paper feed cassette 762 by the pickup roller 761 and conveyed to the nip between the intermediate transfer belt 72 and the secondary transfer roller 77. The full-color visible image formed on the surface of the intermediate transfer belt 72 is transferred (secondary transfer) to one side of the sheet 75 by the secondary transfer roller 77 and is fixed to the sheet 75 by passing through the fixing roller pair 78. . The paper discharge roller pair 79 discharges the sheet 75 on which the visible image is fixed through the above steps.

Since the image forming apparatus exemplified above uses an organic light emitting diode element as a light source, the apparatus is made smaller than a configuration using a laser scanning optical system. Note that the present invention can also be applied to image forming apparatuses having configurations other than those exemplified above. For example, a rotary development type image forming apparatus, an image forming apparatus that directly transfers a visible image from a photosensitive drum to a sheet without using an intermediate transfer belt, or an image forming that forms a monochrome image The light emitting device of the present invention can also be used for the device.

Further, the use of the light emitting device according to the present invention is not limited to the exposure of the image carrier. For example, the light-emitting device of the present invention is employed in an image reading device as a line-type illumination device that irradiates a reading target such as an original with light. As this type of image reading apparatus, there is a scanner, a copying machine or a reading part of a facsimile, a barcode reader, or a two-dimensional image code reader for reading a two-dimensional image code such as a QR code (registered trademark).

1 is a perspective view showing a partial configuration of an image forming apparatus according to the present invention. It is a top view which shows the structure of a light-emitting device. It is sectional drawing seen from the III-III line in FIG. It is a top view which shows the structure of the light-emitting device which concerns on a modification. It is sectional drawing which shows the structure of the light-emitting device which concerns on a modification. It is a top view which shows the structure of the light-emitting device which concerns on a modification. 1 is a cross-sectional view illustrating a configuration of an image forming apparatus according to the present invention.

Explanation of symbols

H: Light emitting device, U (U1, U2) ... Unit, 10 (10a, 10b) ... Substrate, E ...
Light emitting element, 15 ... IC chip, 20 ... support, 21 ... plate-like part, 22 ... side wall part, 2
5: Adhesive, 30 ... Converging lens array, 70 ... Photosensitive drum, 72 ... Image forming surface.

Claims (9)

Comprising a plurality of unit parts arranged in a predetermined direction;
Each of the plurality of unit parts is
A substrate that is a separate body for each unit;
And a plurality of light emitting elements arranged on the surface of the substrate along the predetermined direction. Each of the plurality of unit parts is
The light-emitting device according to claim 1, further comprising: a drive circuit that drives the plurality of light-emitting elements of the unit part. Comprising a single support to which the plurality of unit parts are fixed;
The light-emitting device according to claim 1, wherein the support body faces each of the substrates across the light-emitting elements of the plurality of unit portions. The support includes a plate-like portion facing each substrate of the plurality of unit portions, and a side wall portion protruding from the plate-like portion toward the substrate and having an end surface bonded to the substrate,
The light emitting device according to claim 3, wherein each light emitting element of the plurality of unit parts is sealed in a space surrounded by the side wall part in a gap between the substrate and the plate-like part. 5. The light emitting device according to claim 4, wherein the side wall portion includes a portion interposed in a gap between the plurality of light emitting elements of each unit portion and the plurality of light emitting elements of other unit portions adjacent to the unit portion. The light emitting device according to claim 1, wherein end surfaces of adjacent substrates are bonded to each other. The light emitting device according to any one of claims 1 to 6, wherein each of the plurality of unit portions has the same structure. An image carrier on which a latent image is formed by exposure; and
The light emitting device according to any one of claims 1 to 7, wherein the image carrier is exposed;
An image forming apparatus comprising: a developing unit that forms a visible image by adding a developer to the latent image formed on the image carrier. The image carrier includes an image forming surface that travels in the sub-scanning direction,
The image forming apparatus according to claim 8, wherein the light emitting device is arranged such that the plurality of unit portions are arranged in a main scanning direction.

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