JP2003270568A - Optical write-in device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the occurrence of thermal influence to an optical system and also to reduce a cost. <P>SOLUTION: The housing 50 of an optical write-in device 5 is divided into upper and lower surface sides by a partitioning member 50C, and a light deflector 62 and fθ lenses 63 and 64 are disposed on the upper surface side, and long toroidal lenses (WTL) 69-72 are disposed on the lower surface side. The fθ lenses 63 and 64 are formed of glass, and the long toroidal lenses (WTL) 69-72 which are hardly affected by the heat of the light deflector 62 are formed of plastic. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical writing device for irradiating a surface to be scanned of an image carrier with a light beam to write a latent image,
And an image forming apparatus such as a copying machine, a printer, a facsimile, and a plotter, which is provided with the optical writing device and forms an image.

[0002]

2. Description of the Related Art Light beams emitted from a plurality of light sources are
A latent image is written by irradiating four image carriers (for example, photoconductor drums) arranged side by side, and the latent images formed on the respective image carriers are developed with different color developers (for example, yellow and magenta). , Cyan, and black toner) to develop a visible image, and then transfer the transfer material such as recording paper carried on the transfer / transport belt to the transfer portion of each image carrier to sequentially transfer each image carrier. A tandem-type color image forming apparatus is known in which a visible image of each color formed above is transferred onto a transfer material in a superimposed manner, and then the transferred image is fixed on the transfer material to obtain a multicolor image. .

7 and 8 show an example of an optical writing device used in a tandem type color image forming apparatus. The optical writing device 100 includes four light source units 52, 53, 54, 5
5 and light beams L1, L2, L from each light source unit
It has an optical deflector 62 that deflects and scans 3 and L4 in two symmetrical directions. The optical deflector 62 has a driver I
It is provided with electric components for controlling the motor rotation such as C, a capacitor, and a resistor and a coil for rotating the motor. Further, a plurality of light beams which are arranged symmetrically with respect to a vertical axis passing through the light deflector 62 and are deflected and scanned by the light deflector 62 are respectively placed on the scanning surfaces of the corresponding photoconductor drums 1, 2, 3, 4. It has an optical system for guiding and forming an image. The optical system includes optical elements such as fθ lenses 63 and 64, long lenses 69, 70, 71 and 72, and mirrors 65, 66, 67 and 68 for folding the optical path. These components described above are housed in one housing 50.

The housing 50 has a partition member 50A on which an optical deflector 62 and an optical system are arranged, and a frame-shaped side wall 50B surrounding the periphery of the partition member 50A. The partition member 50A is substantially the side wall 50B. The housing 50 is provided in the central portion to partition the housing 50 into upper and lower parts. The four light source units 52, 53, 54, 55 are the side walls 5 of the housing 50.
0B, and the optical deflector 62 is arranged substantially in the center of the partition member 50A of the housing 50. The partition member 50A has light passage openings 50A-1, 50A-2, 50A for allowing the beam to reach the mirrors in the lower region.
-3, 50A-4 are formed.

In the optical writing device 100, the color-separated image data input from an unillustrated original reading device (scanner) or image data output device (personal computer, word processor, facsimile receiver, etc.) is used to drive a light source. The light is converted into a signal, and the light source (semiconductor laser (LD)) in each of the light source units 52, 53, 54, 55 is driven accordingly, and a light beam is emitted. The light beams L1, L2, L3, and L4 emitted from the light source units 52, 53, 54, and 55 pass through the cylindrical lenses 56, 57, 58, and 59 for face tilt correction, directly or via the mirrors 60 and 61. To the optical deflector 62,
Deflection scanning is performed in two symmetrical directions by two-stage polygon mirrors 62a and 62b which are rotated at a constant speed by a polygon motor.

Two-stage polygon mirror 62 of the optical deflector 62
The light beams, which are deflected and scanned in two directions by two beams by a and 62b, respectively pass, for example, fθ lenses 63 and 64 having an upper and lower two-layer structure, and a second imaging lens 69 formed of a long toroidal lens (WTL). , 70, 71, 72, and is reflected by the first folding mirrors 65, 66, 67, 68. The first folding mirrors 65, 66, 67, 68 are arranged above the partition member 50A. After that, the light beam is transmitted through the openings 50A-1, 50A-2, 50A-.
After passing through 3, 50A-4, it is reflected or transmitted by an optical element such as the second folding mirrors 73, 75, 77, 79, and irradiated on the surface to be scanned of the photoconductor drums 1, 2, 3, 4. Then, the electrostatic latent image is written.

In the optical writing device in such a tandem type color image forming apparatus, as described above, the optical deflector 62 including the polygon mirror and the driving motor for the polygon mirror, and fθ provided near the optical deflector 62. The fθ lenses 63 and 64 having the characteristics are arranged, and then the long lenses 69, 70, 71, and 72 are located in the same space (on the same surface).
It is located in. The optical deflector 62 has a heat source such as a driver IC for driving a drive motor, a condenser, a resistor, and a coil, and heat is generated by friction due to high-speed rotation of the rotary shaft of the motor. For this reason, when the polygon mirror rotates, the driver IC and the like generate heat, and due to the airflow during rotation, the temperature of the space on the upper surface of the partition member where the optical deflector is arranged rises more than that of the space on the lower surface of the partition member. To do.

Due to this temperature rise, the fθ lenses 63, 6
4. The long lenses 69, 70, 71, 72 are thermally affected, causing a change in the write magnification and a change in the write position (beam spot position and beam diameter), which causes image deterioration. There is. To prevent these problems,
fθ lenses 63, 64 and long lenses 69, 70, 71,
72 is a glass lens having a relatively small linear expansion coefficient.

Further, the circumference of the optical deflector 62 is hermetically closed to fθ.
It is also attempted to reduce the thermal influence on the lenses 63, 64 and the like. That is, as shown in FIG. 8, the optical deflector 62 is provided by the housing wall 600 shown by hatching and the sealing glass (used for the passage of the optical path) 601.
The surrounding area is hermetically sealed.

[0010]

However, when glass is used for the lens, there is a problem that an increase in cost cannot be avoided. In the configuration that seals around the optical deflector,
Although the temperature influence on the fθ lens and WTL is reduced, the temperature rise of the optical deflector itself becomes high and the driver IC
Since it will be used beyond the operating temperature range of (1), a member (fan, heat sink, etc.) for cooling it will be required, resulting in an increase in cost. Further, there is a problem that extra cost is generated for the glass for sealing the space.

Therefore, the main object of the present invention is to provide an optical writing device capable of suppressing the thermal influence on the optical system and reducing the cost, and an image forming apparatus equipped with the optical writing device. .

[0012]

In order to achieve the above object, in the invention described in claim 1, a light source, an optical deflector for deflecting and scanning a light beam from the light source, and a deflective scanning by the optical deflector. In an optical writing device comprising an optical system that guides a focused light beam onto a corresponding surface to be scanned and forms an image, the light source, the optical deflector, and the optical system are housed in one housing. The optical deflector is divided by a partition member, the optical deflector is disposed on one surface side of the partition member, and the optical system is separately disposed with the partition member interposed therebetween. The optical element arranged on the opposite side is made of a material having a larger linear expansion coefficient than the optical element arranged on the same side.

According to a second aspect of the present invention, in the optical writing apparatus according to the first aspect, the optical element arranged on the same side as the optical deflector is made of glass and the optical element arranged on the opposite side. The element is made of plastic.

According to a third aspect of the present invention, in the optical writing device according to the first aspect, the partition member is formed of a material having a lower thermal conductivity than the main body of the housing. .

According to a fourth aspect of the invention, in the optical writing device according to the first aspect, the partition member is made of a material having a smaller linear expansion coefficient than the main body of the housing. .

According to the invention of claim 5, claim 1 or 2
In the optical writing device described above, a configuration is adopted in which an optical element having a large volume in the optical system is arranged on the side opposite to the optical deflector.

According to a sixth aspect of the present invention, in the optical writing device according to the first aspect, the partition member has an opening for passing light, and the opening is closed with a light transmitting material. , Is adopted.

According to a seventh aspect of the present invention, in the optical writing device according to the first aspect, a part of the optical deflector projects to the opposite side, and the periphery of the projecting portion is made of the same material as the partition member. The structure is such that it is covered in a sealed state.

According to an eighth aspect of the present invention, in the optical writing device according to the first aspect, a part of the optical deflector projects to the opposite side, and an enclosing portion surrounding the projecting portion is formed. The part is made of the same material as that of the partition member, and is open to the outside of the housing.

According to a ninth aspect of the present invention, an image carrier, an optical writing unit that irradiates a scanning surface of the image carrier with a light beam to write a latent image, and the latent image is visualized. 9. An image forming apparatus, comprising: a developing unit for performing a transfer, a transfer unit for transferring the visible image to a transfer material, and a fixing unit for fixing the image transferred on the transfer material.
The optical writing device according to any one of the above is adopted.

[0021]

DETAILED DESCRIPTION OF THE INVENTION A first embodiment of the present invention will be described below with reference to FIGS. It should be noted that parts common to those of the conventional configuration will be denoted by common reference numerals, and redundant description will be omitted. 1 is a cross-sectional view of the optical writing device, FIG. 2 is a plan view of the optical writing device, FIG. 3 is a diagram showing a scanning state in FIG. 2, and FIG. 4 is a schematic configuration of an image forming apparatus including the optical writing device. It is a figure. First, the outline of the configuration and operation of the image forming apparatus will be described with reference to FIG. The image forming apparatus having the configuration shown in FIG. 4 is a full-color image forming apparatus in which a plurality of drum-shaped photoconductive photoconductors (photosensitive drums) 1, 2, 3, 4 are juxtaposed as a plurality of image carriers. The four photoconductor drums 1 to 4 are, for example, yellow (Y), magenta (M), cyan (C), and black (B
The image corresponding to each color of k) is formed. The order of colors is not limited to this and can be set arbitrarily.

A charging unit (charging roller, charging brush, charging charger, etc.) for forming an image by an electrophotographic process is provided around each of the four photosensitive drums 1 to 4.
6, 7, 8, 9 and the light beams L1 to L1 from the optical writing device 5.
L4 exposure section, developing section (developing device for each color of Y, M, C, Bk) 10, 11, 12, 13 and transfer / conveying belt 2
2a and transfer means (transfer roller
(Transfer brush, etc.) 14, 15, 16, 17 and a transfer / transport device 22 and cleaning units (cleaning blade, cleaning brush, etc.) 18, 19, 20, 21 etc. It is possible to form an image of each color in 1 to 4.

Below the four photosensitive drums 1 to 4 arranged side by side, a transfer roller 22a stretched around a driving roller and a plurality of driven rollers is arranged. It is being conveyed in the direction shown. Further, a plurality of paper feed units 23 and 24, which accommodate transfer materials such as recording paper, are installed at the bottom of the main body of the image forming apparatus.
The transfer material accommodated in the transfer rollers 3 and 24 passes through the transfer roller 2 via the paper feed roller, the transfer roller pair, and the registration roller pair 25.
The sheet is fed to 2a, and is carried and conveyed by the transfer / conveying belt 22a.

The latent images formed on the photoconductors 1 to 4 by the optical writing device 5 correspond to Y, M, C and B of the developing units 10 to 13, respectively.
The toner image of each color of Y, M, C, and Bk is developed with the toner of each color of k and visualized. The images are transferred onto the transfer material carried on top of each other in sequence. The transfer material on which the four-color image is transferred is the fixing device 26.
After being conveyed to the sheet, the fixing device 26 fixes the image, and the sheet is discharged onto the sheet discharge tray 28 by the sheet discharge roller pair 27.

As shown in FIG. 2, in the optical writing device 5, 4
One light source unit 52, 53, 54, 55 is the optical deflector 6
They are arranged symmetrically with respect to an axis passing through 2. Further, as shown in FIG. 1, the optical writing device 5 includes a plurality of light beams L1 to L4 which are deflected and scanned by the optical deflector 62.
Optical systems (image forming lenses 63, 64, 69) that guide and form images on the surfaces to be scanned of the corresponding photosensitive drums 1 to 4, respectively.
-72, mirrors 65-68, 73-8 for folding the optical path
Optical members (optical elements) such as 0), and these constituent members are housed in one housing 50. In the housing 50, fθ lenses 63 and 64 (first image forming lenses), long toroidal lenses (WTL) 69 to 72 (second image forming lenses), which are optical elements forming an optical system, and optical paths. Mirrors 65-5 for folding back
8, 73 to 80 and the like are arranged separately on both surfaces (upper surface side and lower surface side) of the partition member 50C. Also, the housing 5
0 are provided with covers 87 and 88 on the upper and lower portions thereof, and a cover 87 on the lower side is provided with an opening through which a light beam passes, and the dust-proof glasses 83, 84, 85, and
86 is attached.

The optical writing device 5 converts the color-separated image data input from a document reading device (not shown) or the like into a signal for driving a light source in the same manner as the conventional example, and in accordance therewith, each of the light source units 52 to 55. A semiconductor laser (LD) which is a light source in the inside is driven to emit a light beam, pass through cylindrical lenses 56 to 59 for plane tilt correction, and reach an optical deflector 62 directly or via mirrors 60, 61, The polygon motor 62c is rotated at a constant speed, and the two-stage polygon mirrors 62a and 62b are deflected and scanned in two symmetrical directions. The polygon mirrors 62a and 62b are used for the light beams L2 and L.
Although it is divided into upper and lower two stages for the light beam for the light beam No. 3 and for the light beams L1 and L4, it is also possible to deflect the four light beams by a thick polygon mirror.

Polygon mirrors 62a, 6 of the optical deflector 62
The light beams, which are deflected and scanned in two directions by two beams by 2b, respectively pass through the fθ lens lenses 63 and 64, are folded by the first folding mirrors 65 to 68, and are opened by the opening portions 50C-1 and 50C- of the partition member 50C. 2,50C-
3, 50C-4, after passing through the long toroidal lens (WTL) lenses 69 to 72 disposed on the lower surface side of the partition member 50C, the second folding mirror 73, 75,
77, 79, third folding mirror 74, 76, 78, 8
0, through the dustproof glasses 83 to 86, the surface to be scanned of the photoconductor drums 1, 2, 3, 4 for each color is irradiated to write an electrostatic latent image.

Each of the four light source units 52 to 55 is composed of a semiconductor laser (LD) which is a light source and a collimator lens for collimating the luminous flux emitted from the semiconductor laser.
These are the structures that are integrated into the holder,
A light source unit for black (for example, a light source unit of reference numeral 54) that is often used when forming a black and white image is a multi-beam provided with a set of two or more light sources (LD) and a collimating lens in order to enable high speed writing. It may be configured. In the case of the multi-beam configuration, the side wall 5 of the housing 50
If the light source unit is configured to be rotatable about the optical axis with respect to 0B, the beam pitch in the sub-scanning direction can be adjusted, and the pixel density (for example, 600 dpi,
(1200 dpi etc.) can be switched.

In the optical path of each of the light beams L1 to L4, there is provided a synchronization detecting mirror (not shown) for taking out the light beam at the scanning start position in the main scanning direction, and the light beam reflected by the synchronization detecting mirror is The synchronization detectors 81 and 82 receive the light and output a synchronization signal for starting scanning. As shown in FIG. 3, the scanning direction of the light beam deflectively scanned by the optical deflector 62 is the main scanning direction.
4 in the axial direction. The direction perpendicular to the main scanning direction is the sub-scanning direction, which is the rotating direction of the photosensitive drums 1 to 4 (moving direction of the surface of the photosensitive drum), and further the conveying direction of the transfer / conveying belt 22a described later. is there. That is, the width direction of the transfer / transport belt 22a is the main scanning direction, and the transport direction is the sub-scanning direction.

As described above, the optical system installation space of the housing 50 is divided into upper and lower parts by the partition member 50C having a low heat conductivity, that is, a heat insulating property, and the optical deflector 62 which emits heat is arranged on the upper surface side. It is set up. In the present embodiment, the main body of the housing 50 is integrally formed of resin, and the partition member 50C is formed of a member having a high heat insulating property.
As the member having a high heat insulation property, for example, a resin mixed with glass fiber, a member having a low thermal conductivity or a member having a configuration in which a member having a low thermal conductivity is sandwiched between resins can be employed. In the above optical system, the fθ lenses 63 and 64 arranged on the same side (upper surface side) as the optical deflector 62 are made of glass,
Long toroidal lens (WTL) 69 disposed on the opposite side, that is, on the lower surface side that is less susceptible to the thermal influence of the polarizer 62.
Numerals 72 to 72 are formed of plastic (for example, polycarbonate or acrylic) which is a material having a larger linear expansion coefficient than glass. The polygon motor 62c of the optical deflector 62 projects to the lower surface side region, but the periphery of the polygon motor 62c extends over the range of the lower cover 87 and the partition member 50.
It is sealed with a side wall integrally formed with C. For this reason, the heat emitted from the optical deflector 62 is suppressed from moving to the lower surface side due to the heat insulating property of the partition member 50C, and stays only on the upper surface side.

Since the temperature increase on the lower surface side is suppressed, even if the long toroidal lenses (WTL) 69 to 72 are made of plastic, they are not easily affected by heat. When the optical element arranged on the lower surface side is made of inexpensive plastic, it is possible to prevent the deterioration or change in the characteristics of the optical element due to heat and improve the performance, and when the optical element arranged on the lower surface side is also made of glass. The cost can be reduced compared to. In the present embodiment, in particular, a long toroidal lens (WTL) 6 which is an optical element having a large volume, in other words, a large projection area from the top (large size).
Since 9 to 72 are disposed on the lower surface side and made of plastic, the cost reduction rate is high.

The partition member 50C may be formed of a material (for example, aluminum) having a linear expansion coefficient smaller than that of the main body (plastic) of the housing 50. In this case, the thermal influence on the position of the optical element can be suppressed with high accuracy.

Next, a second embodiment will be described with reference to FIG. Note that the same parts as those in the above-described embodiment are denoted by the same reference numerals, and unless otherwise necessary, the description of the configuration and the function that has already been made will be omitted and only the main parts will be described (the same applies to other embodiments below). In the present embodiment, openings 50C-1, 50C-2, 50C- that allow light to pass from the upper surface side to the lower surface side.
3, 50C-4 is glass 90A as a light transmissive material,
It is characterized by being blocked by 90B, 90C and 90D. The heat generated on the upper surface side is applied to the openings 50C-1 and 50.
The purpose is to prevent convection to the lower surface side through C-2, 50C-3, and 50C-4 and to reduce the characteristics of the optical element formed of plastic or the like and susceptible to thermal influence. Although cost reduction cannot be expected so much by newly providing the glasses 90A, 90B, 90C, and 90D, it is possible to highly accurately prevent deterioration of the characteristics of the optical element formed of plastic or the like.

Next, a third embodiment will be described with reference to FIG. In each of the above-described embodiments, the periphery of the polygon motor 62c, which is a part of the light deflector 62 protruding to the lower surface side, is sealed with the same material as the partitioning member 50C in the lower surface side region. There is a possibility that the temperature will rise on the lower surface side, and the purpose is to prevent this. The periphery of the polygon motor 62c is surrounded by an enclosing portion 91 made of the same material as the partition member 50C.
The lower end of 1 penetrates the lower cover 87 and opens to the outside of the housing 50. That is, the polygon motor 62c
Is exposed to the air outside the housing 50. Since the heat of the polygon motor 62c is diffused to the outside of the housing 50 and is cooled by the air outside the housing 50, the temperature rise in the lower surface side region can be suppressed with high accuracy and the optical deflector 62 can be air-cooled. .

[0035]

According to the present invention, the light source, the light deflector for deflecting and scanning the light beam from the light source, and the light beam deflected and scanned by the light deflector are associated with the object. An optical system for guiding and forming an image on the scanning surface, and the light source,
In an optical writing device in which the optical deflector and the optical system are housed in one housing, the housing is partitioned by a partition member, and the optical deflector is disposed on one surface side of the partition member. The optical system is arranged separately with the partition member interposed therebetween, and the optical element disposed on the opposite side of the optical deflector in the optical system has a linear expansion coefficient higher than that of the optical element disposed on the same side. Since it is made of a large material, a part of the optical system can be made of plastic which is cheaper than glass, for example, and it is possible to reduce the cost and suppress the adverse effect of the heat of the optical deflector. can do.

According to the invention of claim 2 or 9, in the optical writing device of claim 1, the optical element arranged on the same side as the optical deflector is made of glass and arranged on the opposite side. Since the installed optical element is made of plastic, it is possible to improve the writing performance and to reduce the cost by using the glass optical element only on one side of the partition member. You can

According to the third or ninth aspect of the invention, in the optical writing apparatus according to the first aspect, the partition member is made of a material having a lower thermal conductivity than the main body of the housing. Therefore, the adverse effect of heat of the optical deflector can be further suppressed.

According to the invention of claim 4 or 9, in the optical writing device of claim 1, the partition member is formed of a material having a smaller linear expansion coefficient than the main body of the housing. Therefore, the adverse effect of the heat of the optical deflector on the position of the optical element can be suppressed with high accuracy.

According to the invention described in claim 5 or 9, in the optical writing device according to claim 1 or 2, an optical element having a large volume in the optical system is arranged on the side opposite to the optical deflector. Since the configuration is adopted, the cost reduction rate can be increased.

According to the sixth or ninth aspect of the invention, in the optical writing device according to the first aspect, the partition member has an opening for passing light, and the opening is covered with a light transmitting material. Since the configuration is such that the heat is applied to the opposite side of the optical deflector, it is possible to highly accurately suppress the adverse effect.

According to the invention of claim 7 or 9, in the optical writing device of claim 1, a part of the optical deflector projects to the opposite side, and the periphery of the projected part is the partition member. Since the structure is covered with the same material in a hermetically sealed state, it is possible to highly accurately suppress the adverse effect of heat of the optical deflector on the opposite side.

According to the eighth or ninth aspect of the invention, in the optical writing device according to the first aspect, a part of the optical deflector projects to the opposite side, and a surrounding portion surrounding the projected part is formed. Since the surrounding portion is made of the same material as the partition member and is open to the outside of the housing, it is possible to suppress the adverse effect of the heat of the optical deflector on the opposite side with higher accuracy. You can

[Brief description of drawings]

FIG. 1 is a sectional view taken along line AA of FIG. 2 of an optical writing device according to a first embodiment of the present invention.

FIG. 2 is a plan view of an optical writing device.

3 is a diagram showing a scanning state in FIG.

FIG. 4 is a schematic front view of the image forming apparatus.

FIG. 5 is a sectional view of an optical writing device according to a second embodiment.

FIG. 6 is a sectional view of an optical writing device according to a third embodiment.

FIG. 7 is a cross-sectional view of a conventional optical writing device.

FIG. 8 is a plan view of a conventional optical writing device.

[Explanation of symbols]

50 housing 50C partitioning members 50C-1, 50C-2, 50C-3, 50C-4 openings 52, 53, 54, 55 light source unit 62 optical deflector 63, 64 fθ lens 69, 70, 71 as an optical element 72 Long Toroidal Lens as Optical Element 91 Enclosure

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C362 AA46 BA04 BA50 BA51 BA85                       DA33                 2H045 AA01 CA63 DA02 DA41                 5C051 AA02 CA07 DB22 DB30 DC07                 5C072 AA03 BA12 DA02 DA04 HA02                       HA06 HA09 HA13 XA05

Claims (9)

[Claims] 1. A light source, an optical deflector that deflects and scans a light beam from the light source, and an optical system that guides and images the light beam deflected and scanned by the optical deflector onto a corresponding surface to be scanned. An optical writing device in which the light source, the optical deflector, and the optical system are housed in one housing, the housing is partitioned by a partition member, and the optical deflector is provided on one surface side of the partition member. The optical system is arranged separately with the partition member interposed therebetween, and the optical element disposed on the opposite side of the optical deflector in the optical system from the optical element disposed on the same side. An optical writing device, which is also formed of a material having a large linear expansion coefficient. 2. The optical writing device according to claim 1, wherein the optical element arranged on the same side as the optical deflector is made of glass, and the optical element arranged on the opposite side is made of plastic. And an optical writing device. 3. The optical writing device according to claim 1, wherein the partition member is made of a material having a lower thermal conductivity than the main body of the housing. 4. The optical writing device according to claim 1, wherein the partition member is formed of a material having a linear expansion coefficient smaller than that of the main body of the housing. 5. The optical writing device according to claim 1, wherein an optical element having a large volume in the optical system is arranged on the opposite side of the optical deflector. 6. The optical writing device according to claim 1, wherein the partition member has an opening for passing light, and the opening is closed with a light transmissive material. Writing device. 7. The optical writing device according to claim 1, wherein a part of the optical deflector projects to the opposite side, and the periphery of the projecting portion is covered with the same material as the partition member in a hermetically sealed state. An optical writing device characterized in that 8. The optical writing device according to claim 1, wherein a part of the optical deflector projects to the opposite side, and a surrounding portion is formed to surround the protruding portion, and the surrounding portion serves as the partition member. An optical writing device, which is formed of the same material and is open to the outside of the housing. 9. An image carrier, an optical writing unit that irradiates a light beam on a surface to be scanned of the image carrier to write a latent image, a developing unit that visualizes the latent image, and An image forming apparatus having a transfer means for transferring a visible image to a transfer material and a fixing means for fixing the image transferred on the transfer material, wherein the optical writing means is any one of claims 1 to 8. An image forming apparatus comprising the optical writing device described above.