JP2006323065A - Optical apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce thermal influence from a rotating polygon mirror to an optical component, without having to partition the rotating polygon mirror and the optical component. <P>SOLUTION: The optical apparatus has the rotating polygon mirror 1, which rotates and deflects and scans a light beam, the optical component for focusing the deflected and scanned light beam on an image carrier, and a heat radiating member, which has an exposed part which is exposed to the outside of the optical apparatus, conducts heat from the inside of the optical apparatus to the exposed part and radiates the heat from the exposed part. At least a part of the heat radiating member for radiating the heat of an air flow, which is directed from the rotating polygon mirror to the optical component due to the rotation of the rotating polygon mirror, is arranged along the rotating polygon mirror on the upstream side of the air flow. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical device used in an image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile.

  A conventional technique will be described with reference to FIGS. FIG. 10 shows an image forming apparatus (printer) for printing a color image.

  The image forming apparatus includes a photosensitive drum (image carrier) 20 for forming an image of each color of yellow, magenta, cyan, and black. The photosensitive drum 20 is obtained by applying a photosensitive layer to a conductor. The image forming apparatus also includes an optical device 21, a developing device 22, an intermediate transfer belt 23, a paper feed cassette 24 for storing sheets (recording material; transfer material), a fixing device 25, a paper discharge tray 26, and a charger 27. .

  The image forming operation is performed as follows. First, the charger 27 uniformly charges the surface of the photosensitive drum 20. Based on image information input from an image reading device (not shown) or a personal computer, the optical device 21 irradiates laser light to form an electrostatic latent image on the photosensitive drum 20. Next, the developing unit 22 applies the frictionally charged toner to the electrostatic latent image on the photosensitive drum 20 to form a toner image. The respective color toner images respectively formed by the four photosensitive drums 20 are sequentially transferred onto the intermediate transfer belt 23. The superposed toner images (unfixed images) are retransferred to the sheet conveyed from the paper feed cassette 24 and fixed on the sheet by applying heat and pressure from the fixing unit 25. The sheets after image formation are stacked on the paper discharge tray 26.

  FIG. 11 is a diagram showing the image forming unit of FIG. The optical apparatus shown in FIG. 11 has a configuration in which four photosensitive drums (image carriers) are exposed at once. In addition to this configuration, there are an optical device configured to expose only one photosensitive drum, an optical device configured to expose two photosensitive drums, and the like.

  In general, the optical apparatus includes a polygon mirror (rotating polygonal mirror) 29 that deflects and scans laser light (light beam), fθ lenses 30a and 30b that perform spot imaging on a photosensitive drum and constant speed scanning of the laser light, and predetermined laser light. It has the reflective mirror 31 which reflects in the direction. The light beam emitted from the light source based on the image information is guided onto the photosensitive drum through the polygon mirror 29, the fθ lenses 30a and 30b, and the reflection mirror 31. The polygon mirror 29 is fixed to a polygon motor (not shown) and is rotationally driven by the polygon motor. These parts are accommodated in the optical box 32. Each component is attached to the optical box 32 with screws or springs. By attaching an upper lid 33 to the optical box 32, the inside of the optical device is sealed to prevent intrusion of dust.

  12 is a view of the optical device as seen from the direction of arrow A in FIG. In FIG. 12, the reflection mirror and the optical box are not shown. At the time of image formation, the polygon mirror 29 rotates in the direction of arrow a in the figure, and deflects and scans the light beam emitted from the light source 34. In the optical apparatus of FIG. 12, two fθ lenses 30a and 30b are arranged symmetrically with respect to the polygon mirror, and light beams emitted from the two light sources 34 are deflected and scanned by the polygon mirror 29, respectively, and fθ dedicated to each optical path. The light is guided to the photosensitive drum through the lenses 30a and 30b and the reflecting mirror.

In an optical device having a polygon mirror, the temperature rise due to heat generated by the polygon motor becomes a problem. This is because the heat of the motor causes the optical components such as a lens disposed around to thermally expand, causing spot fluctuation, magnification change, irradiation position fluctuation, and the like, thereby reducing the image quality.

  Conventionally, the following method has been proposed for this problem. As described in Patent Document 1, the heat of the substrate is absorbed by the steel plate attached to the back surface of the substrate of the polygon motor, and the heat is released from the other end of the steel plate to the outside of the machine.

  Even with such a configuration, in the vicinity of the polygon motor, the amount of heat generated is greater than the amount of heat released depending on the frequency of use, and the temperature rises. As a result, heat is sprayed onto optical components such as lenses as the polygons rotate. As a result, the blown lens or the like undergoes thermal expansion. For this reason, it is preferable to reduce the influence of heat in the vicinity of the polygon motor regardless of the frequency of use of the polygon motor.

On the other hand, in order to prevent the heat from the polygon motor from being blown to the lens or the like, the polygon mirror part is partitioned from the optical parts such as the lens as described in Patent Document 2 and Patent Document 3, and There is a configuration in which the heat of the polygon mirror part is radiated to the outside.
JP 11-242177 A JP 2000-2854 A JP-A-10-123447

  However, if the polygon mirror portion is configured to be partitioned from optical components such as lenses, a new partitioning component is required, which increases the number of components and increases the size of the optical device. Therefore, it is preferable to reduce the influence of heat generated from the polygon motor on the optical component without partitioning the polygon mirror, which is a rotating polygon mirror, from the surrounding optical components.

  Accordingly, an object of the present invention is to reduce the influence of heat from the rotary polygon mirror on the optical component side without partitioning the rotary polygon mirror and the optical component.

  In order to achieve the above object, the present invention employs the following configuration.

  According to a first aspect of the present invention, a rotary polygon mirror that rotates and deflects and scans a light beam, an optical component that forms an image of the deflected and scanned light beam on an image carrier, and an outside of the optical device are exposed. And a heat radiating member that conducts heat from the inside of the optical device to the exposed portion and dissipates heat from the exposed portion. At least a part of the heat dissipating member for dissipating the heat of the air flow toward the optical device is arranged along the rotary polygon mirror on the upstream side of the air flow.

  According to a second aspect of the present invention, there is provided a rotary polygon mirror that rotates and deflects and scans the first light beam and the second light beam, and an image for forming the first light beam that has been deflected and scanned on the first image carrier. A first optical component, a second optical component disposed on the opposite side of the first optical component with respect to the rotary polygon mirror, and a second optical component for forming an image on the second image carrier, which is deflected and scanned; In an optical device having first and second heat dissipating members that extend from the inside of the optical device to the exposed portion, and the internal heat is conducted to the exposed portion and dissipated from the exposed portion, rotation of the rotating polygon mirror Therefore, at least a part of the first and second heat radiating members for radiating the heat of the air from the rotary polygon mirror toward the optical component side corresponds to the side where each laser scan starts with respect to the rotary polygon mirror. Arranged along the rotary polygon mirror, the heat dissipation by the first heat dissipation member and the second heat dissipation member An optical device characterized by comprising.

  According to a third aspect of the present invention, there is provided an image forming apparatus having an unfixed image forming unit that forms an unfixed image and a fixing unit that fixes an unfixed image on a recording material. The image forming apparatus having the optical device according to the second aspect is characterized in that the heat dissipating member that dissipates the heat of the air toward the heat dissipates less than other heat dissipating members.

  According to the present invention, since the air propagation of heat inside the optical device can be suppressed with a simple configuration, the influence of heat from the rotary polygon mirror on the optical component side can be reduced without partitioning the rotary polygon mirror and the optical component. can do.

  In addition, in an optical device including a plurality of optical systems, it is possible to reduce the occurrence of color misregistration with a simple configuration by alleviating the uneven temperature increase due to the environmental temperature unevenness.

  Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. The optical apparatus described below is used in an image forming apparatus such as an electrophotographic copying machine, a printer, or a facsimile. Regarding the configuration of the image forming apparatus and the entire configuration of the optical apparatus, a known configuration can be adopted in addition to the configurations shown in FIGS. 10 and 11, and thus description thereof is omitted here.

(First embodiment)
FIG. 1 is a perspective view showing the main part of the optical device according to the first embodiment of the present invention, FIG. 2 is a schematic view showing the arrangement of components near the polygon mirror and the flow of wind, and FIG. It is a figure which shows the structure of a cover and a cooling member.

  This optical device (scanning optical device) forms a polygon mirror 1 (rotating polygonal mirror) that deflects and scans a light beam and the light beam deflected and scanned by the polygon mirror 1 onto a photosensitive drum (image carrier). A lens 2 (optical component), an optical box 4 (housing) and lid 5 for storing them, a cooling member 3 that is a heat radiating member that cools an air flow blown to the lens 2 by rotation of the polygon mirror 1, Is provided.

  In this optical apparatus, as shown in FIG. 2, the polygon mirror 1 rotates in the direction of arrow a, and the light beam X emitted from the laser light source is deflected and scanned in the range from Y1 to Y2. Hereinafter, the region upstream of the lens 2 in the rotational direction of the polygon mirror 1 is referred to as “scanning start side region”, and the region downstream of the lens 2 in the rotational direction of the polygon mirror 1 is referred to as “scanning end side region”.

  When the polygon mirror 1 rotates, an air flow is generated around the polygon mirror 1 (see “wind flow” in FIG. 2). The heat generated by the rotational drive of the polygon motor is diffused inside the optical device by this air flow. Since no partition is provided between the polygon mirror 1 and the lens 2, warm air flows to the lens 2 side by the rotation of the polygon mirror 1, and a part of the air is blown directly onto the lens 2.

  The temperature rise of the polygon motor itself and the heat conduction through the surrounding parts can be suppressed, for example, by attaching a heat sink or the like to the shaft portion of the polygon motor. However, even if the shaft portion is cooled, it is not possible to solve the temperature rise factor in which the heat generated from the coil of the polygon motor, the driving IC, etc. is propagated by the air flow.

Therefore, in this embodiment, in order to suppress such heat air propagation, a metal such as aluminum or a material having high thermal conductivity is used in the vicinity of the polygon mirror 1 in the scanning start side region, even if it is other than a metal. A configured cooling member 3 is provided. The cooling member 3 is disposed outside the optical device including the cooling unit disposed in the vicinity of the polygon mirror 1 (that is, in the air flow blown to the lens 2 by the rotation of the polygon mirror 1), and the optical box 4 and the lid 5. And an exposed portion that is exposed. Since the exposed part is exposed to a lower temperature space than the inside of the optical device, the heat of the polygon motor that has propagated air (that is, the heat of the air flow) is absorbed by the cooling part and dissipated outside the apparatus by the exposed part. Is done. The material of the cooling member 3 should just be a thing with high heat conductivity, for example, may be a single material, such as an aluminum plate and a steel plate, and may be a thing like a Peltier device.

  The arrangement of the cooling member 3 will be described in detail. The cooling member 3 suppresses heat propagation to the optical component (lens 2) due to the air flow, and thus is provided in the air flow blown to the lens 2. A part (cooling part) of the cooling member 3 is disposed along the polygon mirror 1 on the upstream side of the air flow. Specifically, as shown in FIG. 2, the cooling unit 3 is disposed on the side of the polygon mirror 1 and the polygon motor, and in the scanning start side region. The cooling part of the cooling member 3 extends in the rotation direction of the polygon mirror 1 to the vicinity of the reflection part where the polygon mirror 1 reflects the light beam. In particular, in the present embodiment, the line connecting the center of the lens 2 (optical axis center) and the rotation center of the polygon mirror 1, the center of the cooling member 3, and the rotation center of the polygon mirror 1 in the rotation plane of the polygon mirror 1. The cooling member 3 is arranged in a positional relationship such that the connected lines are substantially orthogonal.

  Since the cooling member 3 cools the air flow generated by the polygon mirror 1, the cooling effect decreases as the distance from the polygon mirror 1 increases. Further, the lens 2 has the greatest influence by the heat of the polygon motor. Therefore, the cooling part of the cooling member 3 is preferably arranged closer to the polygon mirror 1 than the lens 2. Specifically, as shown in FIG. 4, the distance between the rotation center of the polygon mirror 1 and the cooling member 3 is r1, and the maximum between the rotation center of the polygon mirror 1 and the effective scanning range (dashed line portion) of the lens 2 is maximum. The cooling member 3 is preferably arranged so that r1 <r2 when the distance is r2.

  According to such an arrangement, the air flow toward the lens 2 flows between the polygon mirror 1 and the cooling member 3, and the heat of the air flow can be effectively absorbed by the cooling member 3. As a result, the temperature rise of the lens 2 can be suppressed. In this embodiment, since the cooling part has an arc shape that follows the shape of the polygon mirror 1, the heat around the polygon mirror can be absorbed substantially evenly, and a good cooling effect can be obtained. The shape of the cooling unit is not limited to the arc shape, and may be a flat plate shape.

  The cooling effect increases as the surface area of the cooling member 3 increases. Therefore, in order to increase the surface area, the cooling member may cover most of the periphery of the polygon mirror 1 (for example, the cooling member is provided not only on the scanning start side but also on the back side or the scanning end side). ). However, at that time, at least a part of the cooling member needs to be arranged in the vicinity of the polygon mirror on the scanning start region side. Further, it is also preferable that the cooling member 3 is composed of a plurality of plate-like bodies as shown in FIG. 5 or a plurality of ribs (fins) 7 are provided in the cooling part of the cooling member 3 as shown in FIG. The ribs are preferably provided in parallel with the air flow.

  The cooling member 3 is attached to the lid 5 or the optical box 4 of the optical device. FIG. 3 shows, as an example, a configuration in which the cooling member 3 is integrally provided on the lid 5 attached to the optical box 4 in order to seal the optical device. FIG. 3A is a perspective view of only the lid 5 as viewed from above, and FIG. 3B is a schematic cross-sectional view of the optical device taken along the line AA in FIG. The cooling member 3 in this example is integrated with the resin lid 5 by insert molding, and the lower end portion (cooling portion) protrudes inside the lid 5 and the upper end portion (exposed portion) extends outside the lid 5. It sticks out. By fixing the lid 5 to the optical box 4, the lower end portion (cooling portion) of the cooling member 5 is disposed in the vicinity of the polygon mirror 1.

  However, the mounting method of the cooling member is not limited to the example of FIG. For example, the cooling member may be fixed to the optical box, and the upper end portion of the cooling member may be exposed to the outside of the apparatus through a hole provided in the lid. Alternatively, the cooling member may be integrated with the optical box by insert molding, and the lower end portion of the cooling member may be exposed to the outside of the apparatus from the bottom or side wall of the optical box. Alternatively, the cooling member may be fixed by sandwiching the cooling member between the optical box and the lid. In addition, the heat dissipation member is integrally attached to the lid, and the entire lid or the portion where the heat dissipation member is attached is made of the same material as the heat dissipation material or a material having high thermal conductivity, and that portion also serves as the exposed portion of the heat dissipation member But there is no problem.

  In order to increase the heat dissipation efficiency of the cooling member 3, it is also preferable to forcibly cool the exposed portion of the cooling member. For example, as shown in FIG. 7, a duct 6 (flow path) is formed outside the optical device, the exposed portion of the cooling member 3 is exposed in the duct 6, and cooling air from a fan or the like is passed through the duct 6. Thus, the cooling member 3 may be forcibly cooled. Thereby, the cooling effect of the cooling member 3 further improves. The shape of the exposed portion of the cooling member 3 is not necessarily the same as the shape of the cooling portion, and may be a flat plate shape as shown in FIG. It is also preferable to provide a plurality of ribs (fins) in the exposed portion in order to assist heat dissipation of the cooling member 3.

  As described above, according to the present embodiment, the air flow blown to the lens 2 can be effectively cooled with a simple configuration in which the cooling member 3 is provided in the scanning start side region. Even without partitioning, the influence of heat from the rotary polygon mirror on the optical component side can be reduced. Therefore, spot fluctuations, magnification changes, irradiation position fluctuations, and the like can be suppressed, and high-quality image formation is possible.

(Second Embodiment)
FIG. 8 is a diagram showing the arrangement of components near the polygon mirror and the flow of wind in the optical device according to the second embodiment of the present invention.

  The optical apparatus according to the present embodiment includes a polygon mirror 1 (rotating polygonal mirror) that deflects and scans light beams X and X ′, and light beams Y1 and Y2 that are deflected and scanned by the polygon mirror 1 as photosensitive drums (first image carrier). ) The first lens 2 (first optical component) to be imaged on and the light beams Y1 'to Y2' deflected and scanned by the polygon mirror 1 are imaged on another photosensitive drum (second image carrier). The second lens 2 ′ (second optical component), the polygon mirror 1, the optical box and lid for storing the first and second lenses 2, 2 ′, and the air blown to the first lens 2 by the rotation of the polygon mirror 1. And a cooling member 3 for cooling the flow. The second lens 2 ′ is disposed at a position opposite to the first lens 2 and the polygon mirror with respect to the polygon mirror 1.

  This optical apparatus is applied to an image forming apparatus having a plurality of photosensitive drums. A plurality of light beams X and X ′ (first and second light beams) emitted from a plurality of laser light sources are deflected by a single polygon mirror 1 and respectively passed through a first lens 2 or a second lens 2 ′. Guided to a photosensitive drum. That is, in FIG. 8, in the scanning optical system on the left side of the polygon mirror, the polygon mirror 1 rotating in the direction a deflects and scans the light beam X in the range from Y1 to Y2, and in the scanning optical system on the right side of the polygon mirror, The mirror 1 deflects and scans the light beam X ′ in the range from Y1 ′ to Y2 ′.

In an optical apparatus in which a plurality of optical systems are arranged around the polygon mirror 1, a difference in environmental temperature (ambient temperature) between the optical systems causes a color shift. In the example of FIG. 8, there is a heat source such as a fixing device on the left side of the optical device, and the environmental temperature is higher on the left side than on the right side of the optical device (hereinafter, the side where the environmental temperature is far from the heat source is low). The “low temperature side” and the high temperature side that is close to the heat source is called the “high temperature side”. Due to such an environmental temperature gradient, the temperature of the first lens 2 disposed on the high temperature side is likely to be higher than that of the second lens 2 ′ disposed on the low temperature side. Then, variations such as spot variation, magnification variation, irradiation position variation, and the like occur between the left and right optical systems, and color misregistration occurs.

  Therefore, in the present embodiment, in order to suppress the propagation of heat due to the air flow and to correct the temperature difference between the optical systems as described above, the polygon mirror 1 is upstream of the first lens 2 in the rotational direction. And the cooling member 3 is provided in the rotation direction downstream side of the polygon mirror 1 rather than 2nd lens 2 '. The configuration of the cooling member 3 is the same as that of the first embodiment.

  With the above configuration, the airflow blown to the first lens 2 on the high temperature side is cooled, so that the temperature rise of the first lens 2 can be suppressed. In addition, since only the high-temperature air flow is cooled, the temperature deviation between the first lens 2 and the second lens 2 'is alleviated. Therefore, the temperature difference between the left and right optical systems can be made sufficiently small, variations in magnification, irradiation position, and the like can be suppressed, and the occurrence of color misregistration can be suppressed.

(Third embodiment)
FIG. 9 is a diagram showing the arrangement of components near the polygon mirror and the flow of wind in the optical device according to the third embodiment of the present invention.

  In the second embodiment, only the cooling member 3 (first heat radiating member) that cools the air flow blown to the first lens 2 (first optical component) on the high temperature side is provided. However, in the third embodiment, the low temperature side is provided. A second cooling member 3 ′ (second heat radiating member) is further provided for cooling the air flow blown to the second lens 2 ′ (second optical component). The other configuration is the same as that of the second embodiment.

  As shown in FIG. 9, the second cooling member 3 ′ is upstream of the second lens 2 ′ (second optical component) in the rotational direction of the polygon mirror 1, and the first lens 2 (first optical component). It is arranged downstream of the component) in the rotation direction of the polygon mirror 1.

  The distances between the first cooling member and the second cooling member from the polygon mirror are substantially equal, and the surface area of the second cooling member 3 'is smaller than that of the cooling member 3. As a result, the heat dissipation condition of the second cooling member 3' is reduced. Is smaller than the cooling member 3. That is, the cooling portions of the first cooling member 3 and the second cooling member 3 ′ are arranged along the polygon mirror 1 corresponding to the side where the scanning of the respective optical lasers starts with respect to the polygon mirror 1, The first cooling member 3 and the second cooling member 3 ′ are different from each other in heat dissipation (heat dissipation amount, cooling effect). The difference in heat dissipation between the cooling members 3 and 3 ′ is such that the temperature difference between the optical systems due to the above-described gradient of the environmental temperature is eliminated, that is, toward the optical component close to the heat source such as a fixing device. It is preferable that the heat radiation amount of the cooling member 3 that radiates the heat of the air is set to be smaller than the heat radiation amount of the other cooling member 3 '.

  With the above configuration, the temperatures of the left and right optical systems can be made substantially equal, and the occurrence of color shift can be further suppressed.

  With respect to the material and shape of the second cooling member 3 ′, the same effect can be obtained by adopting the same configuration as the cooling member 3 of the first embodiment.

  In addition, in this example, the heat dissipation condition (heat dissipation amount) by the heat dissipation member was made different by changing the surface area of the heat dissipation member, but in addition, the distance (interval) of the heat dissipation member from the rotating polygon mirror was changed. By making it different, even if it is the heat radiating member of the same structure, a heat radiating condition can be varied.

As described above, according to the present invention, the influence of heat from the rotating polygon mirror on the optical component side can be reduced without partitioning the rotating polygon mirror and the optical component.

The perspective view which shows the principal part of the optical apparatus which concerns on 1st Embodiment. The schematic diagram which shows the components arrangement | positioning of the polygon mirror vicinity of the optical apparatus which concerns on 1st Embodiment, and the flow of a wind. The figure which shows the structure of the cover and cooling member of the optical apparatus which concern on 1st Embodiment. The figure which shows the positional relationship of a polygon mirror, a lens, and a cooling member. The figure which shows the modification of a cooling member. The figure which shows the modification of a cooling member. The figure which shows the structural example for forcibly cooling a cooling member. The schematic diagram which shows the components arrangement | positioning of the polygon mirror vicinity of the optical apparatus which concerns on 2nd Embodiment, and the flow of a wind. The schematic diagram which shows the components arrangement | positioning of the polygon mirror vicinity of the optical apparatus which concerns on 3rd Embodiment, and the flow of a wind. 1 is a diagram illustrating a configuration of an image forming apparatus. The figure which shows the structure of the conventional optical apparatus. The schematic diagram which shows the components arrangement | positioning of the polygon mirror vicinity of the conventional optical apparatus, and the flow of a wind.

Explanation of symbols

1 Polygon mirror (rotating polygon mirror)
2 Lens (optical component, first optical component)
2 'Second lens (second optical component)
3 Cooling member (heat radiating member, first heat radiating member)
3 'second cooling member (second heat dissipation member)
4 Optical box 5 Lid 6 Duct 7 Rib (fin)

Claims (10)

A rotating polygon mirror that rotates and deflects and scans the light beam, an optical component that images the deflected and scanned light beam on the image carrier, and an exposed portion that is exposed to the outside of the optical device, In an optical device having a heat radiating member that conducts heat from the inside of the optical device to the exposed portion and dissipates heat from the exposed portion,
At least a part of the heat radiating member for radiating the heat of the air flow from the rotary polygon mirror toward the optical component side by the rotation of the rotary polygon mirror is disposed along the rotary polygon mirror upstream of the air flow. An optical device.   The optical device according to claim 1, wherein the heat radiating member is disposed closer to the rotary polygon mirror than the optical component.   The optical device according to claim 1, wherein the heat radiating member has an arc shape that follows the shape of the rotary polygon mirror.   The optical device according to any one of claims 1 to 3, wherein the heat dissipating member extends in the rotation direction of the rotating polygon mirror to the vicinity of the reflecting portion where the rotating polygon mirror reflects the light beam.   The optical device according to any one of claims 1 to 4, wherein the optical device is a unit in which a lid is attached to a housing, and the lid is a part of a heat dissipation member. A rotating polygon mirror that rotates and deflects and scans the first light beam and the second light beam, a first optical component that forms an image of the deflected and scanned first light beam on the first image carrier, and a rotating polygon A second optical component disposed on the side opposite to the first optical component with respect to the mirror, for imaging the second light beam that has been deflected and scanned on the second image carrier, and from the inside of the optical device to the exposed portion In the optical device having the first and second heat radiating members that are stretched and the internal heat is conducted to the exposed portion and radiated from the exposed portion,
At least a part of the first and second heat dissipating members for radiating the heat of the air from the rotating polygon mirror toward the optical component side by the rotation of the rotating polygon mirror starts scanning of the laser with respect to the rotating polygon mirror. An optical device, wherein the optical device is arranged along a rotary polygon mirror corresponding to the side, and the heat radiation by the first heat radiation member and the second heat radiation member is different.   In an image forming apparatus having an unfixed image forming unit for forming an unfixed image and a fixing unit for fixing an unfixed image on a recording material, heat of air directed toward an optical component close to the fixing unit is radiated. The image forming apparatus having an optical device according to claim 6, wherein the heat dissipating member has a smaller heat dissipating amount than other heat dissipating members.   The optical device according to claim 6, wherein the first heat radiating member and the second heat radiating member have different surface areas.   The optical device according to claim 6 or 8, wherein a distance between the first heat radiating member and the rotating polygon mirror is different from a distance between the second heat radiating member and the rotating polygon mirror. A rotating polygon mirror that rotates and deflects and scans the light beam, an optical component that images the deflected and scanned light beam on the image carrier, and an exposed portion that is exposed to the outside of the optical device, In an optical device having a heat radiating member that conducts heat from the inside of the optical device to the exposed portion and dissipates heat from the exposed portion,
At least a part of the heat radiating member for radiating the heat of the air flow from the rotating polygon mirror toward the optical component side by the rotation of the rotating polygon mirror is along the rotating polygon mirror on the side where laser scanning starts with respect to the rotating polygon mirror. An optical device characterized by being arranged.

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