JP2006150836A - Optical writing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a distortion of a body chassis of an image forming apparatus from being transferred to an optical housing and to prevent a relative position or an angle of an optical member from being greatly varied, thereby preventing occurrence of color shift. <P>SOLUTION: There is disclosed an optical writing device wherein the optical housing 70 is fixed to the body chassis of the image forming apparatus at a plurality of fixing positions 41-44. The directions X, Y, Z on each of the fixing positions are defined such that X represents an axial direction of an image carrier body, Y represents a sub-scanning direction of an image and Z represents a height direction of the optical housing 70. A condition that the optical housing 70 is pressed against a reference face and is able to be displaced in the other direction is defined to be semi-fixing. The restriction condition with respect to each direction at each fixing position is as follows. One of the restriction positions (restriction [1]) is in the restriction condition: X=fixing or semi-fixing, Y=fixing or semi-fixing and Z=fixing or semi-fixing. One of the other restriction positions (restriction [2]) is in the restriction condition: X=free, Y=fixing or semi-fixing, and Z=semi-fixing. The other restriction position (restriction [3]) is in the restriction condition: X=free, Y=free and Z=semi-fixing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical writing device that forms an electrostatic latent image on an image carrier with a light beam, and an image forming device such as a copying machine, a printer, a plotter, and a facsimile equipped with the optical writing device. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical writing apparatus that emits a light beam and an image forming apparatus that includes the optical writing apparatus and a plurality of image carriers to form a color image. The present invention relates to a technique for preventing the occurrence of deviation.

  In general, a color image forming apparatus such as a laser printer or an electrophotographic copying machine that outputs a multicolor image or a full color image has cyan (C), magenta (M), yellow (Y), and black (K) output three primary colors. A color image is formed by forming a toner image of each color component on an image carrier such as a photosensitive drum and transferring the toner image of each color component in a superimposed manner on a recording medium.

Such a color image forming apparatus includes one optical scanning type optical writing device (optical scanning device) for a plurality of photosensitive drums, and is emitted from an optical housing of the optical writing device (optical scanning device). There is a configuration in which the photosensitive drum is scanned and exposed with the four color light beams.
As described above, in the optical writing device in which the optical system for four colors is provided in one optical housing, a plurality of locations of the optical housing are attached to the main body chassis (metal and resin frame, etc.) of the image forming apparatus. Thus, scanning (image recording) accuracy is ensured.
In this optical writing apparatus, light beams emitted from four beam light sources corresponding to Y, M, C, and K are scanned bidirectionally by a deflector (for example, a rotating polygon mirror) that rotates at a constant speed. Thereafter, after passing through the imaging optical system, the light beam is reflected by the corresponding mirror and guided to the photosensitive drum corresponding to each color.

In such a color image forming apparatus, the optical housing of the optical writing device (optical scanning device) expands and contracts due to a temperature change inside the device, the position where the light beam irradiates the photosensitive drum fluctuates, and color misregistration occurs. There is a problem that it ends up.
As a prior art for solving this problem, in Patent Document 1, the linear expansion coefficient of the housing of the optical writing apparatus is made larger than the linear expansion coefficient of the chassis of the image forming apparatus, and the optical writing apparatus is attached to the image forming apparatus. There has been proposed a method of reducing color misregistration in the process direction by fixing one method and allowing the other to move relatively.

  However, in the first embodiment of the prior art, the direction orthogonal to the process direction is not considered, and the housing of the optical writing device is deformed unevenly due to expansion or contraction due to heat. The change in the mounting posture of the internal optical member is different for each color, and color misregistration cannot be suppressed. Furthermore, in this prior art, it is described that the light beam moves in the process direction by an amount corresponding to the extension of the housing due to the heat extension of the housing of the optical writing device. However, since the housing is not actually a flat plate, Thermal deformation of the housing causes angular variations of the optical member. Therefore, the variation in the scanning position of the light beam is more greatly affected by the angular variation than the variation in the position of the optical member (parallel movement), and the variation in the scanning position of the light beam (color shift) cannot be suppressed.

  In addition, as a method for making it strong against disturbance, there is a method in which the optical housing of the optical writing device is firmly fixed to the chassis of the image forming apparatus at four or more locations. In this case, a color image forming apparatus is installed in the market. Then, the chassis of the image forming apparatus is deformed according to the state of the floor to be installed, and the housing of the optical writing apparatus fixed to the chassis is deformed following the deformation of the chassis. As a result, there is a problem in that the relative positional relationship between the plurality of beams is shifted and the image quality is deteriorated.

  On the other hand, in recent years, in order to reduce the cost of an image forming apparatus, research for manufacturing an optical housing of an optical writing device (optical scanning device) using a low-cost resin material has been conducted. However, the resin is less rigid than the metal and is likely to be thermally deformed. In particular, under conditions where the maintenance of the installation environment is further reduced by reducing the thickness and accuracy of the chassis of the image forming apparatus in order to reduce the cost, it is necessary to pay attention to the linear expansion coefficient of the resin material. (Suppression of color misregistration) could not be achieved.

  Further, in the conventional image forming apparatus, since the inclination of the scanning line on the recording material is determined only by the positional accuracy of the optical writing device and the photosensitive member, the processing error of the constituent parts is accumulated and the structure is deformed or installed due to its own weight. In some cases, the flatness of the location varied greatly. In addition, the optical writing device may require repair / replacement due to a failure or life of a rotating polygon mirror or light source (semiconductor laser, etc.), and the ease of attaching / detaching or replacing the optical housing is important. Furthermore, there is a problem that the image is disturbed by the occurrence of so-called banding in which relative vibration to the photosensitive member occurs due to vibration using the main body drive unit as a vibration source or vibration of the rotary polygon mirror itself.

As a conventional technique for solving the above-described problems, as described in Patent Document 2, the housing of the optical writing device has a protrusion and a reference plane, and the housing is mounted on the mounting portion inside the image forming apparatus. It is known that the optical writing device is positioned on the apparatus main body by forming a positioning hole and a reference plane for mounting the.
However, in the invention described in Patent Document 2, since the attachment reference is both the front end face both ends and the bottom rear end, the accumulation of machining errors is large, the positional accuracy is difficult to be obtained, and there is room for improvement.

JP-A-1-169466 JP-A-8-190256

  In the optical writing device, when the casing expands, contracts, or twists due to temperature changes, the laser light source, the scanning lens, An optical member such as a folding mirror is displaced. In addition, when the fixing position of the optical writing device changes due to temperature changes, installation conditions of the main body, etc., the main body chassis also causes a large displacement in the arrangement of these optical members. As described above, there is a problem in that the spot position of the light beam on the surface of the image carrier changes due to the displacement of the optical member.

The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the amount by which the spot position of the light beam irradiated to the image carrier by the optical writing device varies depending on the temperature change or the installation status of the device. is there.
More specifically, the distortion of the main body chassis of the image forming apparatus is prevented from being directly transmitted to the optical housing, and the occurrence of color misregistration or the like is prevented by preventing a large change in the relative position or angle of the optical member or the like. It is an object of the present invention to provide an optical writing device having a configuration capable of achieving the above and an image forming apparatus including the optical writing device.

In order to achieve the above object, the present invention employs the following technical means.
According to a first aspect of the present invention, there is provided an optical housing that is provided in an image forming apparatus and in which an optical member that constitutes an optical system that deflects a light beam emitted from a light source and guides the light beam onto an image surface is positioned therein, An optical writing apparatus for forming an electrostatic latent image on an image carrier by a light beam emitted from the optical housing, wherein the optical housing is fixed to a plurality of fixing portions of a main body chassis of the image forming apparatus. Direction X, Y, Z at each fixed location
X: axial direction of the image carrier,
Y: image sub-scanning direction,
Z: the height direction of the optical housing,
Defined as quasi-fixed, a state that is pressed against the reference surface by the pressing member and can be displaced in other directions, and the constraint condition for each direction at each fixed location is the constraint condition for only one constraint location The
X: Fixed or semi-fixed,
Y: fixed or semi-fixed,
Z: fixed or semi-fixed,
And one constraint condition among other restraint points,
X: Free
Y: fixed or semi-fixed,
Z: semi-fixed,
And the restraint conditions of other restraint points,
X: Free
Y: Free
Z: semi-fixed,
(Claim 1).

  According to a second means of the present invention, in the optical writing device of the first means, a plurality of cylindrical fixed shapes are formed in the X direction on the outer periphery of the optical housing, and the fixed shape of the optical housing is formed on the body chassis side. Two V-shaped fixed shapes are provided, one end of the cylindrical end surface is pressed against the chassis reference surface by a pressing member, and there is pressing means for pressing the optical housing in the Y direction toward the V-shape. The shape is a plate shape that is received only in the Z direction, and is semi-fixed by a pressing member (claim 2).

  According to a third means of the present invention, in the optical writing device of the first means, a plurality of plate-like projection shapes are formed on the XY plane on the outer periphery of the optical housing, and one of them has a reference round hole shape. The other one has a long hole shape, and the body chassis side is provided with a mounting portion that receives the Z-direction of the plate-like projection and a pin shape that fixes the position at a position corresponding to the hole shape. The other fixed portions are semi-fixed received only by the pressing member in the Z direction (Claim 3).

  According to a fourth means of the present invention, in the optical writing device of the second means, a lever member that is rotatable in a cylindrical shape of the optical housing as a pressing means for pressing the optical housing in the Y direction toward the V shape. And mounting the optical housing in the Y direction toward the V shape by providing a slanting receiving portion on the main body chassis and pressing the protruding portion of the lever member against the sloping receiving portion of the main body chassis by the pressing member. In addition to pressing, pressing means for pressing in the Z direction against other chassis fixing points is provided (claim 3).

  According to a fifth means of the present invention, in the optical writing device of any one of the first to fourth means, a spring member such as a leaf spring or a spring is used as the pressing member. 5).

  According to a sixth means of the present invention, in the optical writing apparatus according to any one of the first to fifth means, a plurality of light sources and light beams emitted from the plurality of light sources are placed in the optical housing. A deflecting means for deflecting; and an optical system for guiding the light beams deflected by the deflecting means onto the image plane, and electrostatic latent images are formed on a plurality of image carriers by a plurality of light beams emitted from the optical housing. It is characterized by forming (Claim 6).

The seventh means of the present invention comprises an image carrier, a charging means for charging the image carrier, an optical writing means for irradiating the charged image carrier with a light beam to form an electrostatic latent image, Developing means for developing and developing the electrostatic latent image formed on the image carrier, transfer means for transferring the visible image on the image carrier to a recording material directly or via an intermediate transfer member, and An image forming apparatus including a fixing unit that fixes an image transferred onto a recording material, wherein the optical writing unit includes any one of first to sixth optical writing devices. (Claim 7).
The eighth means of the present invention is the image forming apparatus of the seventh means, comprising a plurality of image carriers, forming images of different colors on the plurality of image carriers, and images on each image carrier. A multi-color or full-color image is formed by transferring the toner image onto the recording material directly or via an intermediate transfer member (claim 8).

In the present invention, as in the first means, in the optical writing device in which the optical housing is fixed to a plurality of fixed locations of the main body chassis of the image forming apparatus, the directions X, Y, and Z at the respective fixed locations. The
X: axial direction of the image carrier,
Y: image sub-scanning direction,
Z: the height direction of the optical housing,
Defined as quasi-fixed, a state that is pressed against the reference surface by the pressing member and can be displaced in other directions, and the constraint condition for each direction at each fixed location is the constraint condition for only one constraint location The
X: Fixed or semi-fixed,
Y: fixed or semi-fixed,
Z: fixed or semi-fixed,
And one constraint condition among other restraint points,
X: Free
Y: fixed or semi-fixed,
Z: semi-fixed,
And the restraint conditions of other restraint points,
X: Free
Y: Free
Z: semi-fixed,
Thus, when the optical housing expands and contracts in the X and Y directions due to thermal expansion due to environmental temperature changes, the other light beam locations can be displaced in the X and Y directions with reference to one restraint location. The optical housing is not twisted, and the relative position and angle of the optical member in the housing do not change greatly. In addition, even when the optical housing receiving surface is displaced due to a change in the installation location of the main body chassis, the restraint portion other than the reference portion is separated from the receiving portion of the main body chassis due to the rigidity of the optical housing, so that the distortion of the main body chassis becomes optical. Since there is no significant change in the relative position or angle of the optical member or the like without being directly transmitted to the housing, the occurrence of color misregistration or the like can be prevented.

  According to the present invention, as in the second means, in the optical writing device of the first means, a plurality of cylindrical fixed shapes are formed in the X direction on the outer periphery of the optical housing, and the optical chassis is disposed on the main body chassis side. Two V-shaped fixed shapes that receive the fixed shape of the housing are provided, and the cylindrical end surface on one side is pressed against the chassis reference surface by a pressing member such as a spring member, and the optical housing is pressed in the Y direction toward the V-shape. The other chassis fixing shape is a plate shape that receives only in the Z direction and is semi-fixed by a pressing member, so that the same effect as the first means can be obtained and the removal of the optical housing can be performed laterally. This can be done easily from the direction, and the optical housing can be easily attached and detached.

  Further, according to the present invention, as in the third means, in the optical writing device of the first means, a plurality of plate-like protrusion shapes are formed on the XY plane on the outer periphery of the optical housing, and one of them is a reference. It has a round hole shape, the other one has a long hole shape, a mounting portion that receives the Z-direction of the plate-like projection on the main body chassis side, and a position fixed at a position corresponding to the hole shape. By providing a pin shape and semi-fixing the other fixing points that are received only in the Z direction by a pressing member such as a spring member, the same effect as the first means can be obtained, and the optical housing can be easily removed from the vertical direction. The optical housing can be easily attached and detached.

  Further, in the present invention, as in the fourth means, in the optical writing device of the second means, the optical housing rotates as a pressing means for pressing the optical housing in the Y direction toward the V shape. By attaching a possible lever member, providing a slanted receiving portion on the main body chassis, and pressing the protruding portion of the lever member against the sloping receiving portion of the main body chassis by a pressing member such as a spring member, the V-shaped By pressing the optical housing in the Y direction and having pressing means for pressing in the Z direction against other chassis fixing points, the same effect as the second means can be obtained, and the optical housing can be operated in two directions with a simple configuration. The optical housing can be securely fixed, and the optical housing can be easily removed from the side. Can be performed in, it facilitates attachment and detachment of the optical housing.

  In the image forming apparatus according to the present invention, the optical writing device having the above-described configuration and effect is provided as the optical writing unit, so that the spot position of the light beam irradiated to the image carrier by the optical writing device changes the temperature. It is possible to reduce the amount that fluctuates depending on the installation status of the apparatus, and it is possible to prevent the distortion of the main body chassis of the image forming apparatus from being directly transmitted to the optical housing, so that the relative position and angle of the optical member and the like do not change greatly. In this way, occurrence of color misregistration and the like can be prevented.

Hereinafter, the configuration, operation and action of the present invention will be described in detail with reference to the drawings.
First, an embodiment of an image forming apparatus using an optical writing device according to the present invention will be described. FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. This image forming apparatus is a color laser printer 1 adopting an electrophotographic image forming process. In the image forming unit 2 of the color laser printer 1, four photosensitive drums 10Y, 10C, 10M, and 10K as image carriers are arranged in parallel along a belt-like intermediate transfer member (intermediate transfer belt) 11. Around each of the photosensitive drums 10Y, 10C, 10M, and 10K, a charging unit 8, an optical writing device 6 that is an exposure unit, a developing unit 9, a primary transfer unit 12, and a cleaning unit 7 are arranged in order of rotation. It is arranged. A sheet feeding unit 3 for feeding a recording material 3a such as a recording sheet is provided at the lower part of the image forming apparatus. A sheet feeding roller 3b, a registration roller 3c, a secondary roller are arranged along the conveying direction of the recording material 3a. A transfer unit 13, a fixing unit 4, a transport roller 3d, and a paper discharge roller 3e are provided. There is also a support member 3f that supports the paper feed roller 3b.

The charging means 8 is a conductive roller formed in a roller shape. A charging bias voltage is supplied to the conductive roller from a power supply device (not shown), and the surface of each of the photosensitive drums 10Y, 10C, 10M, and 10K is uniform. To charge.
The optical writing device 6 serving as an exposure unit includes four laser light source units, a deflection scanning unit, and an optical system. Based on the image data of each color, the laser light to be turned on / off is supplied to each photosensitive drum 10Y, 10C, 10M. , 10K surface to form an electrostatic latent image on the photosensitive drum.
The developing means 2 develops the electrostatic latent images formed on the photoconductive drums 10Y, 10C, 10M, and 10K in yellow (Y), cyan (C), magenta (M), and black (K). Visualize at.
In the illustrated example, the primary transfer unit 12 is a primary transfer roller to which a transfer bias is applied, and transfers a visible image of each color on each of the photosensitive drums 10Y, 10C, 10M, and 10K to the intermediate transfer body 11.
The cleaning unit 7 removes the developer remaining on the photosensitive drums 10Y, 10C, 10M, and 10K after the transfer.
In the illustrated example, the secondary transfer unit 13 is a secondary transfer roller to which a transfer bias is applied, and transfers the image on the intermediate transfer body 11 to the recording material 3a.
In the illustrated example, the fixing unit 4 is a fixing device having a heating roller and a pressure roller, and fixes the image on the recording material by heating and pressing.

  In the color laser printer 1 having the configuration shown in FIG. 1, when the printing operation is started, the surface of each of the photosensitive drums 10Y, 10C, 10M, and 10K is uniformly charged by the charging unit 8 and then the optical writing device. 6, the surface of each of the photoconductive drums 10Y, 10C, 10M, and 10K is irradiated with laser light based on the image data of each color to form an electrostatic latent image on the photoconductive drum. Then, the electrostatic latent images formed on the respective photosensitive drums 10Y, 10C, 10M, and 10K are visualized with each color developer of the developing means 9. The visualized images on the photosensitive drums 10Y, 10C, 10M, and 10K are transferred to the intermediate transfer member 11 by the primary transfer unit 12 in a superimposed manner. In synchronization with the image transfer to the intermediate transfer body 11, the recording material 3a such as recording paper is separated one by one by the paper feed roller 3b of the paper feeding means 3 and conveyed to the registration roller 3c, and is fed by the registration roller 3c. It is conveyed to a secondary transfer roller 13 which is a secondary transfer means. Then, the image on the intermediate transfer member 11 is collectively transferred to the recording material 3 a by the secondary transfer roller 13. The recording material 3a after the image transfer is conveyed to the fixing unit 4 and heated and pressed by the heating roller and the pressure roller of the fixing unit 4 to fix the image on the recording material 3a. The recording material 3a after fixing is conveyed by a conveyance roller 3d and discharged to a discharge tray by a discharge roller 3e.

  Next, the optical writing device will be described. FIG. 2 is a plan view showing a configuration example of the optical writing device, and FIG. 3 is a schematic sectional view of the optical writing device shown in FIG. The optical writing device 6 includes four laser light source units (LD units) 61Y, 61C, 61M, and 61K that oscillate laser light, and deflection scanning means (rotation) that deflects and scans laser light modulated based on image signals. A deflector 62 such as a polygon mirror), an imaging optical system 63 that forms an image of the laser beam that has been deflected and scanned on the photosensitive member to a desired size, and a synchronization detection unit 64 that detects the scanning start timing of the laser beam. These components (optical members) are held by an optical howling 70 including a housing and a cover. In the present embodiment, four light sources are mounted to irradiate the four photosensitive drums 10Y, 10C, 10M, and 10K with laser light, and the two photosensitive drums 10Y, 10C, 10M, and 10K are divided into two from each side of the rotary polygon mirror that is the deflection scanning means 62. This is an example of a so-called counter scanning system that makes the light incident. A semiconductor laser is used as a light source, and each laser light source has a configuration in which the semiconductor laser, a collimating lens that substantially collimates divergent light emitted from the semiconductor laser, and a semiconductor laser driving circuit board are held by a holding member. Units (LD units) 61Y, 61C, 61M, 61K are configured. Laser light emitted from the LD units 61Y, 61C, 61M, and 61K passes through the aperture 65 and the cylinder lens 66, and reaches the rotary polygon mirror 62 that is a deflection scanning unit. Note that a mirror 67 is inserted in one of the optical paths in order to allow two lights to enter the rotary polygon mirror 62 independently from one side.

When the rotational speed of the rotary polygon mirror 62 is fast enough to exceed 30000 rpm, the soundproof glass 68 is often used in front of the rotary polygon mirror 62 for noise countermeasures or the like. In the figure, a soundproof glass 68 is disposed on both sides of the rotary polygon mirror 62.
The laser beam deflected and scanned by the rotary polygon mirror 62 is incident on the imaging lens 63 again through the soundproof glass 68. Thereafter, the light guided to each of the photoconductive drums 10Y, 10C, 10M, and 10K returns to the photoconductive drums 10Y, 10C, 10M, and 10K by using two mirrors 69 to return the optical path. The imaging lens 63 is composed of a single lens having both the fθ characteristic and the characteristic of narrowing the main and sub beam diameters. The irradiation angle with respect to each photosensitive drum is substantially the same for each of the four.

On the other hand, the synchronization detection means 64 for determining the timing of starting writing returns the beam that has passed through the imaging lens 63 by the synchronization detection mirror 64a. The synchronization detection means 64 includes an imaging lens 64b, an electric circuit board 64d having a photoelectric element 64c, and a holding member (not shown) that holds them.
Since the original meaning of the synchronization detection is to take the timing of the scanning light, it is usually sufficient that it is installed prior to scanning. Further, in order to detect a change in the speed (or time) of one scan, a detection unit may be provided at the rear end of the scan. FIG. 2 shows a configuration in which synchronization is obtained before and after such scanning. In addition, as shown in FIG. 2, the two upper and lower scanning lights are detected by one synchronization detecting means 64.

  FIG. 3 shows an example of a configuration in which laser light is emitted from one optical writing device 6 to all the photosensitive drums with respect to a plurality of photosensitive drums 10Y, 10C, 10M, and 10K. A dustproof member 60 is provided at the exit from the optical writing device 6 to the photosensitive drums 10Y, 10C, 10M, and 10K in order to prevent dust from entering the optical housing 70 of the optical writing device 6. The dustproof member 60 is often flat glass. In FIG. 3, the dustproof member 60 is attached to the cover 71 of the optical writing device 6.

  Next, specific examples of fixing means for the optical housing of the optical writing device will be described.

Example 1
As a first embodiment, FIG. 4 shows an example of a four-point receiver that fixes the optical housing 70 to the main body chassis of the image forming apparatus at four locations. In the case of the four-point receiving, as shown in FIG. 4, the optical writing device 6 is inserted into the receiving portions 41 and 42 (with positioning pins) and the receiving portions 43 and 44 (without pins) of the optical housing formed in the main body chassis. The optical housing 70 is fixed.
Further, in the case of a three-point receiver for fixing the optical housing 70 to the main body chassis of the image forming apparatus at three positions, as shown in FIG. 5, receiving portions 41 and 42 (positioning pins) of the optical housing formed in the main body chassis. The optical housing 70 of the optical writing device 6 is fixed to the presence) and the receiving portion 43 (no pin).

4 or 5, first, the fixed shape of the optical housing restraint [1] corresponding to the receiving portion 41 has a round hole shape that fits into the positioning pin without any gap, and is a pressing member for fixing in the Z direction ( For example, it is positioned by a fastening member such as a leaf spring member 100 or a screw (not shown). The constraint condition of the fixed place of this constraint [1] is
X: Fixed or semi-fixed,
Y: fixed or semi-fixed,
Z: Fixed (when using a fastening member such as a screw) or semi-fixed (pressed against a reference surface by a pressing member such as a leaf spring and displaceable in other directions),
It becomes.

Furthermore, the fixed shape of the restraint [2] of the optical housing 70 corresponding to the receiving portion 42 has a long hole shape that fits the positioning pin in the Y direction without any gap and is free in the X direction, and is in the Z direction. It is positioned by a pressing member (for example, a leaf spring member) 100 for semi-fixing to. The restraint conditions for this fixed location are
X: Free
Y: Fixed,
Z: semi-fixed,
It becomes.

The fixed shape of the restraint [3] of the optical housing 70 corresponding to the receiving portions 43 and 44 is a flat plate shape for restricting only in the Z direction, and a pressing member (for example, a leaf spring member) for semi-fixing in the Z direction. ) 100. The restraint conditions for this fixed location are
X: Free
Y: Free
Z: semi-fixed,
It becomes.

(Example 2)
Next, a second embodiment is shown in FIGS. 7 is a view of the optical housing of the optical writing device as viewed from the bottom surface 72 side, FIG. 8 is a view of the optical housing of the optical writing device as viewed from the side surface side, and FIG. FIG.
As shown in FIGS. 7 to 9, cylindrical fixed shapes 131, 132, 133, and 134 are formed in the X direction at the fixed portion on the outer periphery of the optical housing 70, and the restraint [1], [2] Two V-shaped fixed shapes (receiving portions) 141 and 142 for receiving the fixed shapes 131 and 132 of the optical housing 70 at the fixed location are provided, and the cylindrical end surface on one side is a chassis by a pressing member 101 such as a leaf spring. A pressing means (fixing lever) 110 for pressing the optical housing 70 in the Y direction toward the V-shape is provided at the fixing position of the constraint [3] while pressing against the reference surface. It is semi-fixed by. At this time, the constraint condition of the fixed portion of the constraint [1] (receiving portion 141) is as follows:
X: semi-fixed,
Y: Semi-fixed,
Z: semi-fixed,
It becomes.

Furthermore, the constraint condition of the fixed part of constraint [2] (receiving part 142) is:
X: Free
Y: Semi-fixed,
Z: semi-fixed,
It becomes.

As shown in FIG. 9, the fixing method of fixing the optical housing 70 corresponding to the receiving portions 143 and 144 of the constraint [3] is the fixing lever 110 as the pressing means to the cylindrical fixing portions 133 and 134 of the optical housing 70. And a pressing member (for example, a spring such as a spring) 102 is provided between the optical housing 70 and the fixing lever 110, and the protrusion 110 a of the fixing lever 110 is connected to the main body chassis 140 by the pressing member (a spring such as a spring). The optical housing 70 is pressed against the Z-direction receiving portion of the main body chassis 140 and the optical housing 70 is pressed against the V-shaped receiving portions 141 and 142 as described above. I have to. The constraint condition of the fixed part of this constraint [3] (receiving portions 143 and 144) is:
X: Free
Y: Free
Z: semi-fixed,
It becomes.

Here, the directions X, Y, and Z at the respective fixed locations are as follows:
X: axial direction of the photosensitive drum (image carrier),
Y: image sub-scanning direction,
Z: the height direction of the optical housing,
It is defined as Moreover, semi-fixation is defined as a state in which it can be displaced in another direction by being pressed against a reference surface by a pressing member such as a leaf spring.

  According to the present invention, when the main body chassis and the optical housing 70 are fixed as in the first and second embodiments, the optical housing 70 expands and contracts in the X and Y directions due to thermal expansion due to environmental temperature changes. With respect to the restraint location of the restraint [1], the restraint [2] and the restraint [3] can be freely displaced in the X and Y directions, so that the optical housing 70 is not twisted. There is no significant change in the relative position or angle of the member.

  When the main body chassis and the optical housing 70 are fixed in the Z direction at each fixing point (four locations) with fastening screws or the like as shown in FIG. 6B, the installation location of the image forming apparatus changes. The main body chassis itself is distorted, this distortion distorts the optical housing itself, the relative position and angle of the optical member etc. change, the beam irradiation position on the photosensitive drum shifts and color shift occurs, On the other hand, in the first and second embodiments of the present invention, as shown in FIG. 6A, the constraint condition of the fixed position of the constraint [3] is Z direction: semi-fixed. Since the portion of the restraint 3 is separated from the receiving portion 43 or 44 of the main body chassis due to the rigidity, the distortion of the main body chassis is not directly transmitted to the optical housing 70, and the relative position and angle of the optical member and the like are not greatly changed. Therefore, the color shift does not occur.

  As described above, the image forming apparatus of the present invention includes the optical writing device using the configuration and the fixing method as shown in the first or second embodiment, so that the photosensitive drum is used by the optical writing device. The amount of fluctuation of the spot position of the light beam applied to the light source according to the temperature change or the installation status of the apparatus can be reduced, and the distortion of the main body chassis 140 of the image forming apparatus can be prevented from being directly transmitted to the optical housing 70. Occurrence of color misregistration or the like can be prevented by preventing a large change in the relative position or angle of the optical member or the like.

As described above, the present invention can be suitably applied to an image forming apparatus such as a copying machine, a printer, a plotter, and a facsimile equipped with an optical scanning type optical writing device, and particularly includes a plurality of image carriers. It can be suitably used for a color image forming apparatus having a tandem configuration.
In the embodiment of the present invention, the example of the optical writing device that deflects and scans the light beam on both sides of the rotary polygon mirror as the deflection scanning means has been described. However, the optical writing configured to deflect and scan the light only on one side. Obviously, it may be a device. Further, although described with four colors, it may be configured with three colors, and is also effective for stabilizing the writing position (image resist) in the image forming apparatus of a monochrome machine.

1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention. It is a top view which shows the structural example of the optical writing apparatus which concerns on this invention. FIG. 3 is a schematic sectional view of the optical writing device shown in FIG. 2. FIG. 3 is a schematic diagram illustrating an example of a four-point receiver that fixes an optical housing to a main body chassis of the image forming apparatus at four positions. 3 is a schematic diagram illustrating an example of a three-point receiver that fixes an optical housing to a main body chassis of the image forming apparatus at three positions. FIG. It is explanatory drawing which shows the state of the past and this invention when a main body chassis is twisted. It is the figure which looked at the optical housing fixed to the main body chassis from the bottom face side. It is the figure which looked at the optical housing shown in FIG. 7 from the side surface side. It is a figure which expands and shows the part of restraint [3] of the optical housing of FIG.

Explanation of symbols

1: Color laser printer (image forming device)
3: Paper feeding means 4: Fixing means 6: Optical writing device 8: Charging means 9: Developing means 10Y, 10C, 10M, 10K: Photosensitive drum (image carrier)
11: Intermediate transfer body 12: Primary transfer means 13: Secondary transfer means 41-44: Receiving portions on the main body chassis side 61Y, 61C, 61M, 61K: Laser light source unit (LD unit)
62: Rotating polygon mirror (deflection scanning means)
63: imaging lens 64: synchronization detection means 65: aperture 66: cylinder lens 69: folding mirror 70: optical housing 100: pressing member such as a leaf spring member 101: pressing member such as a leaf spring member 102: pressing member such as a spring 110: Fixing lever (pressing means)
140: body chassis 141, 142: V-shaped receiving portion 143, 144: receiving portion

Claims (8)

A light beam emitted from the optical housing is provided with an optical housing, which is provided in the image forming apparatus and has an optical member that is positioned inside to deflect the light beam emitted from the light source and guide it onto the image plane. In the optical writing device that forms an electrostatic latent image on the image carrier by the optical housing, the optical housing is fixed to a plurality of fixing points of the main body chassis of the image forming device.
The directions X, Y, Z at each fixed point are
X: axial direction of the image carrier,
Y: image sub-scanning direction,
Z: the height direction of the optical housing,
Defined as quasi-fixed, a state that is pressed against the reference surface by the pressing member and can be displaced in other directions, and the constraint condition for each direction at each fixed location is the constraint condition for only one constraint location The
X: Fixed or semi-fixed,
Y: fixed or semi-fixed,
Z: fixed or semi-fixed,
And one constraint condition among other restraint points,
X: Free
Y: fixed or semi-fixed,
Z: semi-fixed,
And the restraint conditions of other restraint points,
X: Free
Y: Free
Z: semi-fixed,
An optical writing device characterized by that. The optical writing device according to claim 1,
A plurality of cylindrical fixed shapes are formed in the X direction on the outer periphery of the optical housing, two V-shaped fixed shapes for receiving the fixed shape of the optical housing are provided on the main body chassis side, and the cylindrical end surface on one side is formed by a pressing member. It has pressing means that presses against the chassis reference surface and presses the optical housing in the Y direction toward the V shape, and the other chassis fixing shape is a plate shape that receives only in the Z direction and is semi-fixed by a pressing member An optical writing device. The optical writing device according to claim 1,
A plurality of plate-like protrusions are formed on the XY plane of the outer periphery of the optical housing, one of which has a reference round hole shape, the other has a long hole shape, A mounting portion for receiving the Z-direction of the plate-like projection and a pin shape for fixing the position at a position corresponding to the hole shape are provided, and other fixing portions are semi-fixed receiving only in the Z direction by a pressing member. An optical writing device. The optical writing device according to claim 2,
As a pressing means for pressing the optical housing in the Y direction toward the V shape, a lever member that can be rotated in a cylindrical shape of the optical housing is attached, and a receiving portion that is inclined obliquely is provided on the main body chassis, and the lever is moved by the pressing member. It has pressing means for pressing the optical housing in the Y direction toward the V-shape by pressing the protruding portion of the member against the inclined receiving portion of the main body chassis, and pressing in the Z direction against other chassis fixing points. An optical writing device. In the optical writing device according to any one of claims 1 to 4,
An optical writing apparatus using a spring member such as a leaf spring or a spring as the pressing member. The optical writing device according to any one of claims 1 to 5,
The optical housing includes a plurality of light sources, deflecting means for deflecting each light beam emitted from the plurality of light sources, and an optical system for guiding the light beams deflected by the deflecting means onto the image plane, An optical writing apparatus, wherein electrostatic latent images are formed on a plurality of image carriers by a plurality of light beams emitted from the optical housing. An image carrier, a charging unit for charging the image carrier, an optical writing unit for irradiating the charged image carrier with a light beam to form an electrostatic latent image, and an electrostatic unit formed on the image carrier. Developing means for developing and developing the latent image, transfer means for transferring the visible image on the image carrier directly to the recording material or via an intermediate transfer body, and fixing the image transferred to the recording material In an image forming apparatus provided with a fixing unit that performs
An image forming apparatus comprising the optical writing device according to claim 1 as the optical writing unit. The image forming apparatus according to claim 7.
Multi-color by providing multiple image carriers, forming images of different colors on multiple image carriers, and transferring the images on each image carrier directly onto the recording material or via an intermediate transfer member Alternatively, an image forming apparatus that forms a full-color image.

Images