JP6123496B2 - Optical writing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an optical writing device and an image forming apparatus including the optical writing device.

  Conventionally, a heat radiating plate is generally used for heat dissipation of a heat generating member such as a light emitting substrate of an optical writing device, and this heat radiating plate is attached to a flat portion on the heat generating member with an adhesive or the like. Has been given a heat dissipation effect. However, when the linear expansion coefficients of the heat generating member and the heat radiating plate are different, distortion occurs due to the difference in the amount of thermal expansion when a temperature change occurs.

Therefore, in order to solve the above problem, for example, a technique for absorbing a difference in thermal expansion amount by providing a bent portion having a spring property in the middle of the radiating fin has been proposed (for example, see Patent Document 1).
In addition, a technique has been proposed in which a vertical surface portion and a parallel surface portion are formed in a zigzag shape so that the difference in thermal expansion is absorbed over the entire area using elastic deformation of the vertical surface portion (for example, a patent). Reference 2).
Moreover, the technique which absorbs the difference of thermal expansion amount with the distortion | strain of a pillar part by contacting the heat-emitting member and heat-dissipating the several pillar part standingly arranged from the flat plate is proposed (for example, refer patent document 3). .

JP 2009-196228 A JP 2004-71643 A JP 2004-87612 A

However, in the technique described in Patent Document 1, the difference in thermal expansion can be absorbed with respect to the portion where the bent portion is provided, but the portion where the radiating fin is provided cannot be absorbed. Accordingly, distortion occurs due to the difference in thermal expansion that cannot be absorbed, and thus it is difficult to apply to an apparatus that requires high-precision positioning such as an optical writing apparatus.
In the techniques described in Patent Documents 2 and 3, the contact area between the heat generating member and the heat radiating plate is greatly reduced, so that heat transfer to the heat radiating plate is difficult to be performed, and the heat radiating efficiency is lowered and the heat radiating efficiency is lowered. Inconveniences such as uniformity occur.

Further, the light emitting substrate of the optical writing device is formed in a substantially rectangular shape, and the length in the longitudinal direction is as long as 300 mm or more. A plurality of light emitting points (light emitting elements) are arranged along the longitudinal direction on the light emitting substrate, but temperature unevenness at each light emitting point leads to performance deterioration of the optical writing device. Certain heat dissipation is required.
At the same time, the required specification of the relative positional accuracy between the light emitting point and the optical element in the direction in which the light emitting substrate emits light is very high. For example, the distortion at the time of temperature change due to the difference in linear expansion coefficient between the light emitting substrate and the heat sink is 1 In the case where the elastic portion is absorbed, the strain at the portion where the elastic portion is not provided affects the performance, and thus a mechanism for uniformly absorbing the strain in the entire length direction is required.

  Furthermore, the light-emitting substrate of the optical writing device is formed very thin and generally has a lack of rigidity alone. Therefore, it is preferable to improve the rigidity of the light emitting direction by the heat radiating plate because there is a risk of bending in the light emitting direction with both ends in the long direction as nodes due to attachment distortion when fixing the light source unit to the apparatus main body. .

  The present invention provides an optical writing device capable of improving the rigidity in the light emission direction and preventing the occurrence of distortion due to the difference in linear expansion coefficient between the light emitting substrate and the heat radiating plate without reducing the heat dissipation efficiency, and An object of the present invention is to provide an image forming apparatus including the optical writing device.

The invention described in claim 1 has been made to achieve the above object,
In the optical writing device,
A light emitting substrate comprising a plurality of light sources;
An optical element for condensing the light emitted from the light source on the image carrier;
A holder for holding the light emitting substrate and the optical element;
A heat radiating plate for radiating heat generated by the light emitting substrate;
With
The light emitting substrate extends in a long direction and a short direction perpendicular to the long direction in a plane perpendicular to the light emission direction,
The heat sink is
Affixed with a plurality of affixed portions spaced apart along the longitudinal direction of the light emitting substrate,
A heat dissipating part coupled to all the pasting parts;
With
The pasting part and the heat radiating part are arranged on different planes ,
The heat radiation member, in the order in which the sticking portion is arranged, characterized that you coupled alternately with one end and the other end portion in the short direction of the light emitting substrate.
The invention according to claim 2 is the optical writing device according to claim 1,
The heat radiating portion has a zigzag shape in which a parallel surface portion parallel to the longitudinal direction of the light emitting substrate and a vertical surface portion perpendicular to the light emitting substrate are repeatedly formed.
The invention according to claim 3
In the optical writing device,
A light emitting substrate comprising a plurality of light sources;
An optical element for condensing the light emitted from the light source on the image carrier;
A holder for holding the light emitting substrate and the optical element;
A heat radiating plate for radiating heat generated by the light emitting substrate;
With
The light emitting substrate extends in a long direction and a short direction perpendicular to the long direction in a plane perpendicular to the light emission direction,
The heat sink is
Affixed with a plurality of affixed portions spaced apart along the longitudinal direction of the light emitting substrate,
A heat dissipating part coupled to all the pasting parts;
With
The pasting part and the heat radiating part are arranged on different planes,
The affixing part is affixed to the surface on the light emission direction side,
The heat radiating portion is disposed on a surface opposite to the light emitting direction, and extends without bending in a direction from the proximal end toward the distal end.
According to a fourth aspect of the present invention, in the optical writing device according to the third aspect,
The heat dissipating part is coupled to one end of the light emitting substrate in the short direction.

The invention according to claim 5 is the optical writing device according to any one of claims 1 to 4 ,
The heat radiating part is disposed on a plane parallel to the light emission direction of the light emitting substrate.

The invention according to claim 6 is the optical writing device according to any one of claims 1 to 5 , wherein
The pasting part and the heat radiating part are arranged on planes perpendicular to each other.

The invention according to claim 7 is the optical writing device according to any one of claims 1 to 6 ,
The light source is an OLED;
The heat dissipation plate has a larger coefficient of linear expansion than the light emitting substrate.

The invention according to claim 8 is an image forming apparatus,
An image carrier;
A charging unit for charging the image carrier;
Optical writing device according to any one of claims 1 to 7 to form an electrostatic latent image on the image bearing member by irradiating light to the charging unit said image bearing member charged by When,
A developing unit that visualizes the electrostatic latent image into an image by a developer by supplying a developer to the image carrier irradiated with the light;
A transfer section for transferring an image formed by the developer onto a recording medium;
A fixing unit that fixes the image of the developer transferred by the transfer unit to the recording medium;
It is characterized by providing.

  ADVANTAGE OF THE INVENTION According to this invention, while improving the rigidity of a light radiation direction, generation | occurrence | production of the distortion by the linear expansion coefficient difference of a light emission board | substrate and a heat sink can be prevented, without reducing heat dissipation efficiency.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an exemplary embodiment. It is a figure which shows schematic structure of the optical print head which concerns on this embodiment. 1 is a perspective view illustrating an overall configuration of an optical print head according to an embodiment. It is a top view which shows an example of a mode that the thermal radiation part of a heat sink is bent. It is a top view which shows schematic structure of a light emitting substrate. FIG. 10 is a perspective view showing an overall configuration of an optical print head according to Modification 1. It is a bottom view which shows the structure of a heat sink. It is a top view which shows an example of a mode that the thermal radiation part of a heat sink is bent. FIG. 10 is a perspective view showing an overall configuration of an optical print head according to Modification 2. FIG. 10 is a side view showing an overall configuration of an optical print head according to Modification 2. It is sectional drawing which shows an example of the XI-XI part of FIG. It is a perspective view which shows the structure of a light-emitting substrate and a heat sink.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  An image forming apparatus 1000 according to the present embodiment is used as, for example, a printer or a digital copying machine. As shown in FIG. 1, a plurality of optical print heads (for each of cyan, magenta, yellow, and black) ( Optical writing device) 100, an image carrier 200 such as a photosensitive drum provided corresponding to the optical print head 100, a charging unit 210 for charging the image carrier 200, and an image carrier irradiated with light. A developing unit 220 that visualizes the electrostatic latent image into an image formed by the developer by supplying the developer to 200, an intermediate transfer belt 300, and a transfer roller (transfer unit) that transfers the image formed by the developer to a recording medium. 400, a fixing unit 500 that fixes an image of the developer transferred by the transfer roller 400 to a recording medium, and the like.

  The image forming apparatus 1000 forms an electrostatic latent image on the image carrier 200 with light emitted from the optical print head 100. Next, the image forming apparatus 1000 supplies the developer to the image carrier 200 on which the electrostatic latent image is formed, thereby visualizing the electrostatic latent image into an image using the developer, and the image is formed on the intermediate transfer belt 300. The image by the developer is transferred. Next, the image forming apparatus 1000 presses and transfers the developer image transferred to the intermediate transfer belt 300 onto the paper P as a recording medium by the transfer roller 400. Next, the image forming apparatus 1000 heats and pressurizes the paper P by the fixing unit 500, thereby fixing the developer image on the paper P. The image forming apparatus 1000 performs the image forming process by conveying the paper P by a paper discharge roller (not shown) and discharging the paper onto a tray (not shown).

  As shown in FIGS. 1 and 2, the optical print head 100 forms an electrostatic latent image on the image carrier 200 by irradiating the image carrier 200 charged by the charging unit 210 with light L. Device. The optical print head 100 includes a light emitting substrate 11 having a plurality of light emitting elements (light sources) 112 that emit light L, and light L emitted from the plurality of light emitting elements 112 provided on the light emitting substrate 11 on the image carrier 200. Refractive index distribution type rod lens array (SLA (registered trademark); Selfoc (registered trademark) Lens Array) 12 (hereinafter referred to as SLA 12), which is an optical element to be condensed, and a heat radiating plate 14 that radiates heat generated by the light emitting substrate 11 These are configured to be held by the holder 13.

In the following description, the long direction of the light emitting substrate 11 shown in FIGS. 2 to 4 and the like is the Y direction, the short direction is the Z direction, and the direction perpendicular to the Y direction and the Z direction is the X direction. In the optical print head 100 shown in FIG. 2 to FIG. In the present embodiment, light L is emitted downward from the light emitting substrate 11 of the optical print head 100 in the X direction. That is, the X direction coincides with the optical axis direction of the light L.
In addition, about FIG. 3, description of SLA12 and the holder 13 is abbreviate | omitted.

  The light emitting substrate 11 is configured by arranging a plurality of light emitting elements 112 in a substantially straight line on a base 111 formed in a substantially rectangular shape (see FIG. 5). Note that a plurality of light emitting elements 112 may be arranged in a plurality of rows on a substantially straight line. When a plurality of light emitting elements 112 are arranged in a plurality of rows, the light emitting elements 112 are arranged in a zigzag pattern, and are arranged slightly shifted in the long direction so that the light emitting elements 112 do not overlap in the short direction of the light emitting substrate 11. In the present embodiment, an organic light-emitting diode (OLED) is used as the light-emitting element 112, and the base 111 of the light-emitting substrate 11 is formed of glass having a small linear expansion coefficient.

  The SLA 12 is disposed between the light emitting substrate 11 and the image carrier 200, and is configured such that a plurality of rod lenses are arranged substantially parallel to the column direction of the plurality of light emitting elements 112 on the light emitting substrate 11. Each of the plurality of rod lenses is formed such that the refractive index at the central axis, that is, the optical axis is low, and the refractive index increases as the distance from the central axis increases. The light beams emitted from the plurality of light emitting elements 112 of the light emitting substrate 11 pass through the plurality of rod lenses of the SLA 12 and are imaged as fine spots on the surface of the image carrier 200.

  The holder 13 is formed of a liquid crystal polymer and is configured to hold the light emitting substrate 11 and the SLA 12. The liquid crystal polymer is desirably made close to the linear expansion coefficient of the base 111 of the light emitting substrate 11 by preparing a material to be blended. The material of the holder 13 is not limited to the liquid crystal polymer, and other resin or metal may be used.

The heat radiating plate 14 is formed by processing a sheet metal such as copper, steel, or aluminum having a larger linear expansion coefficient than glass (the base 111 of the light emitting substrate 11), and includes a pasting portion 141 and a heat radiating portion 142. It is configured.
As shown in FIGS. 3 and 4, a plurality of pasting portions 141 are arranged on the upper surface of the light emitting substrate 11, that is, on the surface opposite to the light emitting direction, with a gap along the longitudinal direction (Y direction). It is pasted. The pasting part 141 is disposed on a plane (YZ plane) perpendicular to the light emission direction of the light emitting substrate 11.
The heat radiating part 142 is coupled to one end part in the short direction (Z direction) of all the pasting parts 141. The heat radiating part 142 is disposed on a plane (XY plane) parallel to the light emission direction of the light emitting substrate 11. That is, the pasting part 141 and the heat radiating part 142 are arranged on a plane perpendicular to each other.

Next, the operation of the optical print head 100 according to the present embodiment will be described with reference to FIG.
According to the optical print head 100 according to the present embodiment, the light L emitted from the plurality of light emitting elements 112 provided on the light emitting substrate 11 passes through the SLA 12 and is a minute spot on the surface of the image carrier 200. Is imaged.
At this time, the plurality of light emitting elements 112 generate heat as the light L is emitted. In the present embodiment, since the heat radiating plate 14 is attached to the upper surface of the light emitting substrate 11, heat generated by the plurality of light emitting elements 112 can be radiated through the heat radiating plate 14.
By the way, the linear expansion coefficient differs between the light emitting substrate 11 made of glass and the heat sink 14 formed by processing a sheet metal. For example, the linear expansion coefficient of glass is 8.5 to 9.0 × 10 ⁻⁶ / ° C., and the linear expansion coefficient of aluminum is 23 × 10 ⁻⁶ / ° C. Therefore, when a temperature change occurs, distortion occurs due to the difference in thermal expansion amount of each member. Therefore, in the present embodiment, a plurality of attaching portions 141 are attached, and the heat radiating portion 142 is coupled to one end portion of all attaching portions 141 in the Z direction. For example, when the temperature of the light emitting substrate 11 is lowered due to a change in ambient temperature, as shown in FIG. 4, the gap between the adhering portions 141 adjacent to each other increases due to the difference in the thermal expansion amount. The difference in thermal expansion amount is absorbed by bending the light emitting substrate 11 in a direction perpendicular to the light emission direction (Z direction in the figure).
In the present embodiment, the pasting portion 141 is pasted over the entire upper surface of the light emitting substrate 11. Therefore, a sufficient contact area between the light emitting substrate 11 and the heat sink 14 can be ensured. Further, heat can be radiated reliably over the entire Y direction of the light emitting substrate 11. Further, the strain can be uniformly absorbed in the entire Y direction of the light emitting substrate 11.
Moreover, in this embodiment, the heat radiating part 142 is arrange | positioned on XY plane. Therefore, the distortion at the time of temperature change can be released in the direction perpendicular to the light emission direction of the light emitting substrate 11 (Z direction in the figure).
Further, in the present embodiment, the attaching part 141 and the heat radiating part 142 are arranged on a plane perpendicular to each other. Therefore, the rigidity of the light emitting substrate 11 in the light emission direction (X direction) can be improved.

As described above, the optical print head 100 according to the present embodiment includes the light emitting substrate 11 including the plurality of light emitting elements 112, the SLA 12 that condenses the light L emitted from the light emitting elements 112 on the image carrier 200, and A holder 13 that holds the light emitting substrate 11 and the SLA 12 and a heat radiating plate 14 that radiates heat generated by the light emitting substrate 11 are provided. Therefore, the heat generated by the light emitting substrate 11 can be radiated through the heat radiating plate 14.
The light emitting substrate 11 extends in a Y direction and a Z direction orthogonal to the Y direction on a plane perpendicular to the X direction, and a plurality of heat sinks 14 are arranged at intervals along the Y direction of the light emitting substrate 11. Affixed with affixed part 141 and a heat radiating part 142 coupled to all the affixed parts 141 are provided. Therefore, when the temperature of the optical print head 100 changes due to the change in ambient temperature, the light emitting board 11 and the heat radiating plate are bent by bending the heat radiating portion 142 in the direction perpendicular to the light emitting direction of the light emitting board 11 (Z direction in the figure). Since the difference in thermal expansion amount with respect to 14 can be absorbed, it is possible to prevent the occurrence of distortion in the X direction that occurs in the light emitting substrate 11 when the temperature changes, and to prevent deterioration in performance and failure due to deformation of components. Can do. Further, since a sufficient contact area between the light emitting substrate 11 and the heat radiating plate 14 can be ensured, problems such as a decrease in heat radiating efficiency and non-uniform heat radiating efficiency can be prevented. Moreover, since heat can be reliably radiated in the entire area of the light emitting substrate 11 in the Y direction, temperature unevenness among the plurality of light emitting elements 112 arranged along the Y direction can be prevented. Furthermore, since the occurrence of distortion in the X direction can be prevented uniformly across the entire Y direction of the light emitting substrate 11, the required specification of the relative positional accuracy between the light emitting element 112 and the SLA 12 can be satisfied.

Further, the pasting portion 141 and the heat radiating portion 142 are arranged on different planes. That is, the heat radiating part 142 is disposed on a plane different from the plane (YZ plane) perpendicular to the light emission direction (X plane) of the light emitting substrate 11. Thereby, since the rigidity of the X direction of the light emission board | substrate 11 can be improved, generation | occurrence | production of the bending to the X direction by the attachment distortion of a light source unit can be prevented.
In particular, according to the optical print head 100 according to the present embodiment, the attaching portion 141 and the heat radiating portion 142 are arranged on planes perpendicular to each other. Therefore, since the rigidity of the light emitting substrate 11 in the X direction can be further improved, the occurrence of bending in the X direction due to the mounting distortion of the light source unit can be prevented with higher accuracy.
Further, according to the optical print head 100 according to the present embodiment, the heat radiating part 142 is arranged on the XY plane. Accordingly, since distortion at the time of temperature change can be released in the Z direction, the occurrence of distortion in the X direction at the time of temperature change can be prevented with higher accuracy.

  As mentioned above, although concretely demonstrated based on embodiment which concerns on this invention, this invention is not limited to the said embodiment, It can change in the range which does not deviate from the summary.

(Modification 1)
For example, in the example illustrated in FIGS. 6 to 8, the structure of the heat dissipation portion 143 is different from that of the heat dissipation plate 14 of the embodiment. For simplification of description, the same reference numerals are given to the same configurations as those in the embodiment, and detailed description thereof is omitted.
In addition, about FIG. 6, description of SLA12 and the holder 13 is abbreviate | omitted.

  The heat dissipating part 143 according to Modification 1 is alternately coupled with one end and the other end in the Z direction of the light emitting substrate 11 in the order in which the pasting parts 141 are arranged. Specifically, the heat radiating portion 143 has a zigzag shape in which a vertical surface portion 143a perpendicular to the Y direction of the light emitting substrate 11 and a parallel surface portion 143b are repeatedly formed, and unevenness is alternately repeated in a plan view. It is formed in a 99-fold shape. And the heat radiating part 143 is provided so as to surround the three sides of each attaching part 141 by the vertical surface part 143a and the parallel surface part 143b.

According to the optical print head 100 according to the modified example 1, since the heat dissipating part 143 has a zigzag shape, the adhering parts 141 are brought closer to each other beyond the limit of the sheet metal punching process as shown in FIG. Can be placed. Therefore, since a sufficient contact area between the light emitting substrate 11 and the heat radiating plate 14 can be ensured, more efficient heat dissipation can be performed.
Moreover, according to the optical print head 100 which concerns on the modification 1, the heat radiating part 143 couple | bonds with one edge part and the other edge part in the Z direction of the light emission board | substrate 11 alternately in the order in which the bonding part 141 was arranged. Therefore, for example, when the temperature of the optical print head 100 is lowered due to a decrease in the ambient temperature, as shown in FIG. 8, the vertical surface portions 143a on both sides are opened outward in the Y direction with the parallel surface portion 143b as the center. It will be distorted. In the first modification, since the parallel surface portions 143b are alternately arranged with one end portion and the other end portion in the Z direction, the distortion of the heat radiating portion 143 when the temperature changes is dispersed on both sides in the Z direction. Thereby, the distortion in the X direction at the time of the temperature change can be surely released in the Z direction, so that the generation of the distortion in the X direction can be prevented with higher accuracy.

(Modification 2)
Moreover, in the example shown in FIGS. 9-12, the structure of the affixing part 144 and the thermal radiation part 145 differs compared with the heat sink 14 of embodiment. For simplification of description, the same reference numerals are given to the same configurations as those in the embodiment, and detailed description thereof is omitted.
As shown in FIG. 12, a plurality of attaching portions 144 according to Modification 2 are attached to the lower surface of the light emitting substrate 11, that is, the surface on the light emission direction side by side with a space along the Y direction. . Specifically, the affixing portion 144 is affixed to each end portion in the Z direction of the light emitting substrate 11 in a line.
The heat radiation part 145 according to the modified example 2 has a zigzag shape in which a vertical surface part 145a and a parallel surface part 145b are repeatedly formed, and is formed in a ninety-nine fold shape in which unevenness is alternately repeated in a plan view. Yes. The heat radiating portion 145 is disposed on the upper surface of the light emitting substrate 11, that is, the surface opposite to the light emission direction. Further, the parallel surface portion 145b extends downward from the end portion in the Z direction of the light emitting substrate 11 and is coupled to the pasting portion 144 disposed at a position corresponding to the parallel surface portion 145b. That is, the heat sink 14B is configured to sandwich the light emitting substrate 11 from the side.

  According to the optical print head 100 according to the modified example 2, since the affixing portion 144 is affixed to the lower surface of the light emitting substrate 11, and the heat radiating portion 145 is disposed on the upper surface of the light emitting substrate 11, a glass substrate. Heat can be radiated without passing through the nitrogen sealing layer 113 having a large thermal resistance formed between the layers 111 (see FIG. 11). Accordingly, when the heat generated by the light emitting element 112 is dissipated, the heat can be dissipated through a path having a smaller thermal resistance, so that more efficient heat dissipation can be performed.

(Other variations)
Moreover, in the said embodiment, although OLED is used as a light source, it is not limited to this. For example, you may make it use LED as a light source instead of OLED.
In the above embodiment, the light emitting substrate 11 having a substantially rectangular shape is described as an example. However, the present invention is not limited to this. The light emitting substrate 11 only needs to extend in the long direction (Y direction) and the short direction (Z direction) orthogonal to the long direction on a plane (YZ plane) perpendicular to the light emission direction. It may be a shape.

Moreover, in the said embodiment, although the thermal radiation part 142 is arrange | positioned on the plane (XY plane) parallel to the light emission direction of the light emission board | substrate 11, it is not limited to this. Any plane other than the plane (YZ plane) perpendicular to the light emission direction of the light emitting substrate 11 may be used.
Moreover, in the said embodiment, although the affixing part 141 and the thermal radiation part 142 are arrange | positioned on a mutually perpendicular | vertical plane, it is not limited to this. The pasting part 141 and the heat radiation part 142 may be arranged on any plane as long as they are not arranged on the same plane.

  Moreover, in the said modification 1, although the thermal radiation part 143 is made to have the zigzag shape in which the vertical surface part 143a and the parallel surface part 143b were formed repeatedly, it is not limited to this. The heat dissipating part 143 may have any structure as long as it is configured to alternately couple one end and the other end in the Z direction of the light emitting substrate 11 in the order in which the pasting parts 141 are arranged. The vertical surface portion 143a may be formed in a curved shape.

  In addition, the detailed configuration of each apparatus constituting the optical print head and the image forming apparatus and the detailed operation of each apparatus can be appropriately changed without departing from the spirit of the present invention.

1000 Image forming apparatus 100 Optical print head (optical writing apparatus)
11 Light Emitting Substrate 111 Base 112 Light Emitting Element (Light Source)
113 Nitrogen encapsulation layer 12 SLA (optical element)
13 Holder 14, 14 B Heat radiation plate 141, 144 Attaching part 142, 143, 145 Heat radiation part 143 a, 145 a Vertical surface part 143 b, 145 b Parallel surface part 200 Image carrier 210 Charging part 220 Developing part 300 Intermediate transfer belt 400 Transfer roller (transfer part) )
500 Fixing part

Claims (8)

A light emitting substrate comprising a plurality of light sources;
An optical element for condensing the light emitted from the light source on the image carrier;
A holder for holding the light emitting substrate and the optical element;
A heat radiating plate for radiating heat generated by the light emitting substrate;
With
The light emitting substrate extends in a long direction and a short direction perpendicular to the long direction in a plane perpendicular to the light emission direction,
The heat sink is
Affixed with a plurality of affixed portions spaced apart along the longitudinal direction of the light emitting substrate,
A heat dissipating part coupled to all the pasting parts;
With
The pasting part and the heat radiating part are arranged on different planes ,
The heat radiation member, in the order in which the sticking portion is arranged, one end and the other to alternately bonded and end optical writing device according to claim Rukoto in the short direction of the light emitting substrate. 2. The optical writing device according to claim 1 , wherein the heat radiating portion has a zigzag shape in which a parallel surface portion parallel to a longitudinal direction of the light emitting substrate and a vertical surface portion perpendicular to the light emitting substrate are repeatedly formed. A light emitting substrate comprising a plurality of light sources;
  An optical element for condensing the light emitted from the light source on the image carrier;
  A holder for holding the light emitting substrate and the optical element;
  A heat radiating plate for radiating heat generated by the light emitting substrate;
  With
  The light emitting substrate extends in a long direction and a short direction perpendicular to the long direction in a plane perpendicular to the light emission direction,
  The heat sink is
  Affixed with a plurality of affixed portions spaced apart along the longitudinal direction of the light emitting substrate,
  A heat dissipating part coupled to all the pasting parts;
  With
  The pasting part and the heat radiating part are arranged on different planes,
  The affixing part is affixed to the surface on the light emission direction side,
  The optical writing device, wherein the heat radiating portion is disposed on a surface opposite to the light emitting direction and extends without bending in a direction from the proximal end toward the distal end. The optical writing device according to claim 3, wherein the heat radiating unit is coupled to one end of the light emitting substrate in the short direction. The heat radiation member, the optical writing device according to any one of claims 1-4, characterized in that provided in the light emission direction parallel to the plane of the light emitting substrate. The bonding between the attaching portion and the heat radiating portion, the optical writing device according to any one of claims 1-5, characterized in that arranged on mutually perpendicular planes. The light source is an OLED;
The heat sink, the optical writing device according to any one of claims 1 to 6, wherein the linear expansion coefficient than the light emitting substrate is large. An image carrier;
A charging unit for charging the image carrier;
Optical writing device according to any one of claims 1 to 7 to form an electrostatic latent image on the image bearing member by irradiating light to the charging unit said image bearing member charged by When,
A developing unit that visualizes the electrostatic latent image into an image by a developer by supplying a developer to the image carrier irradiated with the light;
A transfer section for transferring an image formed by the developer onto a recording medium;
A fixing unit that fixes the image of the developer transferred by the transfer unit to the recording medium;
An image forming apparatus comprising:

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