JP2003072136A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of adequately adjusting in a short time a position on an image carrier body where a laser light is emitted. SOLUTION: A curved surface in a shape tracing an arc R1 around one point an a virtual straight line L1 perpendicular to both of a virtual segment X and a laser scanner unit attachment face 42a at the center XC of the virtual segment X is formed on a lower face of an optical grounding section 94 formed on an optical frame 90. In four optical grounding sections 94, a lower face of each of two optical grounding sections 94 in four optical grounding sections 94 which are away from a photosensitive drum 22 is in a curved face tracing an arc R2 around one point C2 on a virtual straight line L2 which is perpendicular to the virtual straight line L1 and parallel to the laser scanner unit attachment face 42a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser printer,
The present invention relates to an image forming apparatus using an optical scanning device that scans a laser beam to record an image, such as a copying machine or a facsimile machine.

[0002]

2. Description of the Related Art Conventionally, a photosensitive drum is irradiated with laser light carrying image information to form an electrostatic latent image, the electrostatic latent image is developed to form a developed image, and the developed image is recorded. An image forming apparatus that transfers to a medium is known. As such an image forming apparatus, an optical scanning device (hereinafter referred to as a laser scanner unit) is arranged side by side in the lateral direction of a photoconductor unit including a photoconductor drum, a developing device, etc. There is known a type in which a paper feeding device, a paper conveying device, a fixing device, and other parts and members for image formation are arranged side by side in the vertical direction. This type of image forming apparatus is an image forming apparatus having a so-called vertical path configuration, and irradiates the photosensitive drum with laser light from a substantially horizontal direction to write an image on the photosensitive drum.

The laser scanner unit of the image forming apparatus having the above-described vertical path generally includes a laser emitting section for emitting a laser beam carrying image information, a deflection scanning apparatus including a polygon motor and a rotary polygon mirror, an fθ lens, and the like. An optical unit having an imaging lens system is provided.

In this laser scanner unit, the laser light emitted from the laser emitting section is scanned by a polygon mirror which is rotated by a polygon motor of a deflection scanning device to generate fθ.
An image is formed on the surface of the charged photosensitive drum by passing through an imaging lens system such as a lens, whereby an image (electrostatic latent image) is formed on the surface of the photosensitive drum.

By the way, in the image forming apparatus having the laser scanner unit as described above, generally, the laser scanner unit, the photosensitive drum, the paper feeding device, the paper conveying device, the fixing device, and other image forming means are vertically arranged. The main body is composed of the main body frames mounted side by side. In this structure, the laser scanner unit emits laser light in a substantially horizontal direction to irradiate the photosensitive drum. Therefore, due to the accuracy of the position where the laser scanner unit is attached to the main body frame and the accuracy of each component, especially the accuracy of the vertical mounting position, the image writing position on the photosensitive drum may be misaligned or tilted. Deterioration has become a problem, and measures have been taken to resolve this problem. Regarding such measures, FIG. 6 to FIG.
The description will be made with reference to 0.

FIG. 6 is a side view schematically showing the internal structure of an image forming apparatus in which the above measures have been taken. Figure 7
7 is a perspective view showing a laser scanner unit and a photosensitive drum of the image forming apparatus of FIG. FIG. 8 is an example of an image formed by the image forming apparatus of FIG. 6, and FIG. 8A is a schematic diagram showing an image that is inclined and deviated from the main scanning line,
(B) is a schematic diagram showing an image that is shifted in parallel from the main scanning line. FIG. 9 is a side view showing a mechanism for adjusting the position of the laser scanner unit. Figure 10
(A) is a side view showing another mechanism for adjusting the position of the laser scanner unit, and (b) is a side view showing another mechanism.

As shown in FIG. 6, a paper cassette 12 incorporating a cassette tray 14 is detachably attached to the lower portion of the image forming apparatus 10. Cassette tray 1
The recording paper 16 is stacked on the sheet 4. This recording paper 16
Is fed to the feed roller 18 and is paired with the registration roller 20.
Be transported to.

The recording paper 16 being conveyed is a pair of registration rollers 2.
It is temporarily stopped by 0. In this state, the registration roller pair 20 starts to rotate so that the timing at which the electrostatic latent image is written on the photosensitive drum 22 by the laser light emitted from the laser scanner unit 50 matches the timing at which the recording paper 16 is conveyed. The recording paper 16 starts to be conveyed again.

The electrostatic latent image formed on the photosensitive drum 22 is developed by the developing device 24 to form a developed image. The developed image is transferred as a toner image onto the surface of the recording paper 16 sent to the photosensitive drum 22 by the transfer device 26 (hereinafter referred to as a transfer roller). The recording paper 16 on which the toner image has been transferred is conveyed on the conveying path 28 by the photosensitive drum 22 and the transfer roller 26, and reaches the fixing device 30. The toner image on the recording paper 16 transported to the fixing device 30 is fixed on the recording paper 16 by heat and pressure by passing through the heat roller 30a and the pressure roller 30b. As a result, an image is formed on the recording paper 16. The recording paper 16 on which the image is formed is ejected while being sandwiched by the paper ejection rollers 32.

Now, a structure for irradiating the photosensitive drum 22 with the laser light 52 from the laser scanner unit 50 will be described.

A laser beam 52 emitted from a laser emitting portion (not shown) of the laser scanner unit 50 scans a polygon mirror (hereinafter referred to as a polygon mirror) 56 rotated by a polygon motor 54 of a deflection scanning device. Then, the light passes through the image forming lens system of one or a plurality of fθ lenses 58, irradiates the photosensitive drum 22 of the photoconductor unit 40 arranged on the side of the laser scanner unit 50, and an image is formed on the surface thereof. It The polygon motor 54, the polygon mirror 56, the fθ lens 58, and the like described above are included in the optical frame 60 of the laser scanner unit 50.
Is built into. The optical frame 60 has a rectangular shape, and plate-shaped mounting portions 62 for adjusting the position, which will be described later, are formed at four corners of the optical frame 60.

The laser scanner unit 50 and the photoconductor unit 40 are fixed to a body frame 42 made of sheet metal or resin. Therefore, the accuracy of the position (laser writing position) where the laser light is applied to the photosensitive drum 22 is determined by the position where the laser scanner unit 50 is attached to the main body frame 42 and the position where the photosensitive body unit 40 is attached to the main body frame 42. It is affected by the relative positional relationship in the vertical direction.

The laser scanner unit 50 shown in FIG.
As shown in, the polygon mirror 56 and the fθ lens 58
May be displaced or tilted in the sub-scanning direction (the direction of arrow F) due to the accuracy of parts and the accuracy of assembly. When such positional deviation occurs, the position where the laser beam 52 irradiates the photosensitive drum 22 (laser writing position) deviates from the main scanning line X parallel to the longitudinal axis direction of the photosensitive drum 22.

Further, the laser writing position may deviate from the main scanning line X due to the plane accuracy of the laser scanner unit mounting surface 42a of the main body frame 42, the lateral position accuracy in the sub scanning direction, and the like.

As described above, the laser writing position is indicated by the arrow F.
If the main scanning line X is displaced parallel to the direction, the recording paper 1
In the case of No. 6, as shown in FIG. 8B, a phenomenon occurs in which the image lines G are shifted in parallel as a whole. Further, when the laser writing position deviates from the main scanning line X so as to be inclined, the phenomenon that the image line G is obliquely written on the recording paper 16 occurs as shown in FIG. 8A. Among these phenomena, the phenomenon in which the image line G is entirely displaced from the main scanning line X as shown in FIG. 8B can be corrected by software. However, when the image line G is written obliquely with respect to the main scanning line X as shown in FIG. 8A, correction by software processing involves difficulty in processing capacity and processing time. It is necessary to mechanically correct the position where the laser scanner unit 50 is attached to the laser scanner unit attachment surface 42a of the main body frame 42.

In order to perform this mechanical correction, there is known a mechanism capable of adjusting the mounting position of the laser scanner unit 50 in the sub-scanning direction (arrow F direction) of the main body frame 42. As shown in FIG. 9, one of the adjusting mechanisms includes a plate-shaped mounting portion 62 of the optical frame 60 and a laser scanner unit mounting surface 42a of the body frame 42, and a height-adjusting spring 64 interposed between the plate-shaped mounting portion 62 and the laser-scanning-unit mounting surface 42a. A mechanism for adjusting the height of the laser scanner unit 50 from the laser scanner unit mounting surface 42a by inserting a fixing screw 66 from the upper side of the mounting portion 62 to a predetermined depth.

As another adjusting mechanism, as shown in FIG. 10, a cylindrical height adjusting support column 68 having a screw thread formed on the outer peripheral surface thereof is incorporated in the plate-like mounting portion 62, and this height is adjusted. The height of the laser scanner unit 50 from the laser scanner unit mounting surface 42a is adjusted by rotating the height adjusting strut 68, and then the fixing screw 70 is provided.
Is a mechanism for fixing the laser scanner unit 50 to the laser scanner unit mounting surface 42a by tightening.

[0018]

However, in the mechanism using the height adjusting spring 64 shown in FIG. 9, the urging force (spring force) of the height adjusting spring 64 is utilized to make the laser scanner unit 50. Is fixed to the laser scanner unit mounting surface 42a, there is a possibility that a positional displacement due to vibration or shock or a permanent displacement of the height adjusting spring 64 may occur. Therefore, it is difficult to completely fix the laser scanner unit 50 to the main body frame 42.

Further, the height adjusting column 68 shown in FIG.
In the mechanism using, first, the height adjustment support 68
Is rotated to adjust the height, and then the fixing screw 70 is tightened, so that two steps are required at one place. Therefore, as the number of fixed parts increases, the height adjusting time increases and the working time increases. Further, since the height adjusting support column 68 is rotated to adjust the height and then the fixing screw 70 is tightened, the height adjusting support column 68 may rotate during the tightening. This rotation changes the adjusted height. Therefore, in order to prevent unnecessary rotation of the height adjusting support column 68, a rotation stopping jig or a rotation stopping adhesive may be used. However, the work of using these jigs takes time, and there is a problem that the adjustment time is increased and the jig cost is increased accordingly.

Further, as a problem common to the adjusting mechanism shown in FIGS. 9 and 10, since the height adjusting spring 64 and the height adjusting strut 68 are used, the number of parts increases and the cost increases. There is a problem that the assembly work becomes complicated and the working time becomes long. Further, in order to fix the laser scanner unit 50 to the main body frame 42 more stably against vibrations and shocks, when fixing it at the four corners of the optical frame 60, it is necessary to adjust the height at at least two places. There is also a problem that it becomes longer.

In view of the above circumstances, the present invention can adjust the position where the laser scanner unit is fixed to the body frame in a short time, that is, the position where the laser beam irradiates the image carrier can be adjusted appropriately in a short time. An object is to provide a forming device.

[0022]

An image forming apparatus of the present invention for achieving the above object comprises an optical scanning unit having an optical unit for emitting a laser beam carrying image information and an optical frame containing the optical unit. An apparatus, an image carrier on which a predetermined virtual line segment irradiated with the laser light emitted from the optical unit is formed, and a main body frame on which the optical frame is mounted and the image carrier is fixed. In the image forming apparatus, the electrostatic latent image is formed on the image carrier by the laser beam, the electrostatic latent image is developed, and the developed image is transferred to a recording medium to form an image. It is characterized in that it moves along an arc centered on a point on a virtual straight line orthogonal to the virtual line segment at the center of the virtual line segment.

Here, (2) the optical scanning device has an optical ground portion having a curved surface having a shape following the circular arc formed on its lower surface, and (3) the main body frame has the curved surface. A curved surface of the same shape may be formed on the upper surface of the main body grounding part on which the optical grounding part is mounted.

(4) The optical ground portion may be formed on the optical frame.

Further, (5) the optical ground portion may be fixed to the main body ground portion with a screw.

Furthermore, (6) the optical grounding portion has an elliptical shape or a rectangular shape having a long axis extending parallel to the virtual line segment, and a through hole through which a screw penetrates is formed. Good.

Furthermore, (7) a plurality of the through holes are formed in the optical ground portion, and (8) at least one of the plurality of through holes has a short axis length. May have a diameter substantially equal to the outer diameter of the screw.

Furthermore, (9) the optical grounding portion and the main body grounding portion have curved surfaces whose centers coincide with those of the laser light emitted from the optical unit, which illuminates the center of the virtual line segment. It may be formed.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment]

A first embodiment of the present invention will be described with reference to FIGS. 1, 2 and 3.

FIG. 1 is a perspective view showing a laser scanner unit and a body frame of the image forming apparatus of the first embodiment. FIG. 2 is a schematic view showing an adjusting mechanism of the laser scanner unit. FIG. 3 is a schematic view showing the adjustment state of the laser scanner unit. In these figures, FIG.
The same reference numerals are given to the same components as those shown in FIG.

The laser scanner unit 80 (which is an example of an optical unit according to the present invention) includes a light source unit 82 in which a semiconductor laser and a collimator lens are unitized,
A cylindrical lens 86 for condensing the parallel light beam laser light 84 generated from the light source unit 82 on the reflecting surface of the rotary polygon mirror 56 and a scanning light 88 deflected and scanned by the rotary polygon mirror 56 are combined on the photosensitive drum 22. It has an fθ lens 58 which is an image forming optical system for forming an image. Rotating polygon mirror 56, cylindrical lens 86, and fθ lens 58
Etc. are built in an optical frame 90 integrally molded with a resin material. The light source unit 82 is attached to the side wall of the optical frame 90. Optical frame 9
An opening is formed in the upper part of 0. This opening is closed by a lid 92 after assembling each component in the optical frame 90.

The photosensitive drum 22 is disposed on the main body frame 42 integrally formed of a resin material and beside the optical frame 90. The fθ lens 5 is attached to the photosensitive drum 22.
The scanning light 88 that has passed through an opening 94 formed in the side wall 90a of the optical frame 90 via 8 is irradiated.

A motor (not shown) for rotating the rotary polygon mirror 56 is a rotor integrally formed with the rotary polygon mirror 58, and a stator (not shown) integrated with the motor substrate 57.
Have. The stator is excited by the drive current supplied from the drive circuit formed on the motor board 57 to rotate the rotor.

The scanning light 88 focused on the photosensitive drum 22 is
The photosensitive drum 22 is irradiated in the main scanning direction (arrow S direction) by the rotation of the rotary polygon mirror 56, and
The electrostatic latent image is formed on the photosensitive drum 22 by irradiating the photosensitive drum 22 in the sub-scanning direction (direction of arrow F) by the rotation of 2. Around the photosensitive drum 22, a charging device, a developing device, a transfer device, a cleaning device, a charge removing device, a fixing device, a paper feeding device, etc. are provided for forming an image by a known electrophotographic method. However, their illustration is omitted.

Optical ground portions 94 for fixing the optical frame 90 with screws are formed on the laser scanner unit mounting surface 42a of the main body frame 42 at the four corners of the optical frame 90. On the other hand, of the laser scanner unit mounting surface 42a on the body frame 42, the optical grounding portion 94
A laser scanner unit contact seating surface 42b is formed on the surface corresponding to.

When fixing the optical frame 90 to the main body frame 42, the contact seat surface 42b of the laser scanner unit is used.
The optical grounding portion 94 is placed on, adjusted as described later, and fixed with the fixing screw 96.

By the way, the regular portion of the photosensitive drum 22 which is irradiated by the scanning light 88 (correctly designed irradiation portion) is a line segment which coincides with the main scanning line X (the "predetermined virtual line" in the present invention). This is an example of a “minute”, and is hereinafter referred to as a virtual line segment X). On the lower surface of the optical grounding portion 94 formed at the four corners of the optical frame 90, a point on a virtual straight line L1 orthogonal to both the virtual line segment X and the laser scanner unit mounting surface 42a is centered at the center XC of the virtual line segment X. A curved surface having a shape following the circular arc R1 is formed. That is, of the four optical ground portions 94, the lower surfaces of the two optical ground portions 94 close to the photosensitive drum 22 are centered on a point C1 on the virtual straight line L2 which is orthogonal to the virtual straight line L1 and is parallel to the laser scanner unit mounting surface 42a. It is a curved surface that follows an arc. Further, the lower surface of the two optical grounding portions 94 of the four optical grounding portions 94 which are far from the photosensitive drum 22 is centered on a point C2 on the virtual straight line L2 which is orthogonal to the virtual straight line L1 and is parallel to the laser scanner unit mounting surface 42a. The curved surface follows the arc R2.

On the other hand, a curved surface having the same shape as the curved surface of the lower surface of the optical grounding portion 94 is formed on the upper surface of the laser scanner unit contact seat surface 42b. Therefore, the optical frame 9
The optical grounding portions 94 respectively formed at the four corners of 0 and the laser scanner unit grounding bearing surface 42b corresponding to the optical grounding portions 94 have arcs R1 and R2 having the same axis center.
The curved surface follows. As a result, even if the ground planes are not on the same plane, the laser scanner unit 80 is set to C1,
It can be rotated around C2.

To adjust the position for fixing the laser scanner unit 80 to the main body frame 42, refer to FIG.
As shown in (a), the laser scanner unit 80 (and thus the optical frame 90) is moved over the arcs R1 and R2 on the laser scanner unit ground contact surface 42b. As a result, the optical frame 90 moves the centers C1 and C2.
It will rotate on the arcs R1 and R2 around the center. As a result, as shown in FIG. 3, the optical grounding portion 94 rotates in the arrow K direction on the curved surface of the laser scanner unit grounding seat surface 42b. As a result, the laser writing position G on the photosensitive drum 22 is at the center C3 (the straight lines L1 and L2).
The point of intersection is the center of the movement. Therefore, the inclination θ of the laser writing position X in the sub-scanning direction (direction of arrow F)
Can be changed, and the laser writing position G can be appropriately adjusted to the virtual line segment X in a short time.

By the way, in the optical grounding portion 94, through holes 94a and 94b having a long axis extending parallel to the virtual line segment X are formed. The through-hole 94a has four optical grounding portions 9
4 are formed in two optical grounding portions 94 close to the photosensitive drum 22, while the through holes 94b are formed in two of the four optical grounding portions 94 which are farther from the photosensitive drum 22. There is. These through holes 94a, 94
“B” has an elliptical shape or a rectangular shape, and the fixing screw 96 penetrates therethrough. Therefore, even if the laser scanner unit 80 is rotated and moved as described above, the laser scanner unit 80 can be fixed to the main body frame 42. Further, the fixing screw 96 does not interfere with the optical frame 90.

Further, the inner diameters of the two through holes 94a on the minor axis side are substantially equal to the outer diameter of the fixing screw 96. Therefore,
The fixing screw 96 does not move in the laser irradiation direction within the through hole 94a. As a result, the laser scanner unit 80 is rotationally moved while keeping a constant distance (laser irradiation distance) from the photosensitive drum 22 in the laser irradiation direction. [Second Embodiment]

The second embodiment will be described with reference to FIGS. 4 and 5.

FIG. 4 is a perspective view showing a laser scanner unit and a main body frame of the image forming apparatus of the second embodiment. FIG. 5 is a schematic view showing an adjusting mechanism of the laser scanner unit. In these figures, the same components as those shown in FIG. 1 are designated by the same reference numerals.

The basic structure of the image forming apparatus of the second embodiment is the same as that of the image forming apparatus of the first embodiment. The second embodiment is different from the first embodiment in the position of the optical grounding portion 194 formed on the optical frame 190 and the position of the laser scanner unit grounding seat surface 142b corresponding to the optical grounding portion 194. .

The optical scanner 194 and the laser scanner unit grounding seat surface 142b are connected to each other by the laser scanner unit 1.
Of the laser light emitted from 80, the center X of the virtual line segment X
It is formed of a curved surface having an R center on the axis passing through C and is formed directly under the laser beam 88A for irradiating the center XC. A curved surface whose center is located directly below the laser beam 88A is formed on each of the lower surface of the optical grounding portion 194 and the upper surface of the laser scanner unit grounding seat surface 142b.

In adjusting the position where the laser scanner unit 180 is fixed to the body frame 142, as shown in FIG. 5, the laser scanner unit 180 (and hence the optical frame 190) is grounded to the laser scanner unit grounding surface 142b. Move on the arc R3 above.
This causes the optical frame 190 to rotate along an arc R3 centered on the center C4, as shown in FIG. As a result, the optical ground portion 194 rotates in the arrow K direction on the curved surface of the laser scanner unit ground seating surface 142b. As a result, the laser writing position G on the photosensitive drum 22 is at the center C4 (that is, the center X of the virtual line segment X).
Rotate around C). Therefore, since the inclination θ of the laser writing position in the sub-scanning direction (direction of arrow F) can be changed, the laser writing position G can be appropriately adjusted to the virtual line segment X in a short time. Further, since the center of the curved surface coincides with the laser beam 88A for irradiating the center of the virtual line segment X, the center of the image does not deviate from the photosensitive drum 22. Therefore, an image with higher accuracy can be obtained.

[0048]

As described above, in the image forming apparatus of the present invention, when the position (line segment) at which the laser beam emitted from the optical unit irradiates the image carrier deviates from the above virtual line segment, The frame can be moved along the above arc. This arc is an arc centered on a point on a virtual straight line that is orthogonal to this virtual line segment at the center of the virtual line segment to be irradiated by the laser light (image center), so the optical frame is moved along this arc. By doing so, the line segment irradiated with the laser light moves (rotates) around the center of the virtual line segment. Therefore, the position (line segment) where the laser beam emitted from the optical unit irradiates the image carrier can be matched with the virtual line segment. Therefore, the position (line segment) at which the laser beam irradiates the image carrier can be appropriately adjusted in a short time.

Here, the optical scanning device has an optical ground portion having a curved surface having a shape following the circular arc formed on the lower surface thereof, and the body frame has a curved surface having the same shape as the curved surface. In the case where the main body grounding portion on which the optical grounding portion is mounted is formed on the upper surface,
By appropriately sliding the lower surface of the optical grounding portion on the upper surface of the main body grounding portion, the position (line segment) at which the laser beam irradiates the image bearing member can be matched with the virtual line segment. Therefore, the position (line segment) at which the laser beam irradiates the image carrier can be appropriately adjusted in a short time.

When the optical grounding portion is formed on the optical frame, the laser can be moved by appropriately moving the optical frame irrespective of the mounting precision of various parts built in the optical frame. The position (line segment) where the light irradiates the image carrier can be matched with the virtual line segment. Therefore, the position (line segment) where the laser light is applied to the image carrier can be appropriately adjusted in a shorter time.

Further, when the optical grounding part is fixed to the main body grounding part with a screw, the optical grounding part can be fixed to the main body grounding part in a short time.

Furthermore, in the case where the optical ground portion has an elliptical shape or a rectangular shape having a major axis extending parallel to the virtual line segment and a through hole through which a screw penetrates is formed, Since the through hole has both a guide function for moving the grounding part along the above arc and a function for fixing the optical grounding part to the main body grounding part with a screw, it is only necessary to form the through hole in the optical grounding part. Therefore, the optical grounding portion has two functions, so that the optical grounding portion can have a simple structure.

Furthermore, a plurality of the through holes are formed in the optical ground portion, and at least one of the plurality of through holes has a minor axis whose outer diameter is a screw diameter. Is substantially equal, the at least one through hole cannot move in the laser irradiation direction due to the screw, so that the distance between the optical scanning device and the photosensitive drum in the laser irradiation direction can be made constant. Therefore, it is not necessary to separately form a component or the like for keeping the distance constant, and the optical performance (focal length, spot diameter, etc.) of the optical scanning device can be easily configured regardless of the movement of the optical frame. Can be maintained by

Furthermore, the optical ground portion and the main body ground portion are formed with curved surfaces whose centers coincide with those of the laser light emitted from the optical unit and which irradiate the center of the virtual line segment. In this case, since the center of the curved surface coincides with the laser beam (corresponding to the ray axis) that irradiates the center of the virtual line segment, the center of the image does not deviate from the photosensitive drum. Therefore, an image with higher accuracy can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a laser scanner unit and a body frame of an image forming apparatus according to a first embodiment.

FIG. 2 is a schematic view showing an adjusting mechanism of a laser scanner unit.

FIG. 3 is a schematic diagram showing an adjustment state of a laser scanner unit.

FIG. 4 is a perspective view showing a laser scanner unit and a main body frame of the image forming apparatus of the second embodiment.

FIG. 5 is a schematic view showing an adjusting mechanism of a laser scanner unit.

FIG. 6 is a side view schematically showing an internal configuration of an image forming apparatus in which the above measures are taken.

7 is a perspective view showing a laser scanner unit and a photosensitive drum of the image forming apparatus of FIG.

8A and 8B are examples of images formed by the image forming apparatus of FIG. 6, where FIG. 8A is a schematic diagram showing an image that is tilted and deviated from a main scanning line, and FIG. It is a schematic diagram which shows the image shifted parallel to the line.

FIG. 9 is a side view showing a mechanism for adjusting the position of the laser scanner unit.

10A is a side view showing another mechanism for adjusting the position of the laser scanner unit, FIG.
[Fig. 6] is a side view showing still another mechanism.

[Explanation of symbols]

22 Photosensitive drum 42,142 Body frame 42a Laser scanner unit mounting surface 42b Laser scanner unit contact seat surface 80,180 Laser scanner unit 84 laser light 88 scanning light 90,190 Optical frame 94 Optical grounding section 94a, 94b through holes

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C362 AA43 AA45 AA48 BA90 DA02                       DA04                 2H045 AA01 BA02 DA02 DA04 DA41                 2H071 BA03 BA16 DA02                 2H076 AB05 AB12 AB18                 5C072 AA03 BA20 HA02 HA13 HB08                       XA01 XA05

Claims (7)

[Claims] 1. An optical scanning device having an optical unit for emitting a laser beam carrying image information and an optical frame having the optical unit incorporated therein, and a predetermined virtual line irradiated with the laser beam emitted from the optical unit. And an image carrier on which the optical frame is mounted and a main body frame on which the image carrier is fixed, and an electrostatic latent image is formed on the image carrier by the laser light. In an image forming apparatus that develops and transfers a developed image to a recording medium to form an image, the optical frame has a center point on a virtual straight line orthogonal to the virtual line segment at the center of the predetermined virtual line segment. An image forming apparatus, which moves along a circular arc. 2. The optical scanning device has an optical grounding portion having a curved surface having a shape following the circular arc formed on a lower surface thereof, and the body frame has a curved surface having the same shape as the curved surface on an upper surface thereof. The image forming apparatus according to claim 1, wherein a main body grounding portion on which the optical grounding portion is mounted is formed. 3. The image forming apparatus according to claim 2, wherein the optical ground portion is formed on the optical frame. 4. The image forming apparatus according to claim 2, wherein the optical ground portion is fixed to the main body ground portion with a screw. 5. The optical ground portion has an elliptical shape or a rectangular shape having a long axis extending parallel to the virtual line segment, and has a through hole through which a screw penetrates. The image forming apparatus according to claim 4. 6. A plurality of the through holes are formed in the optical ground portion, and at least one of the plurality of through holes has a minor axis whose length is equal to the outer diameter of the screw. The image forming apparatus according to claim 5, wherein the image forming apparatuses are substantially equal to each other. 7. The optical grounding portion and the main body grounding portion are formed with a curved surface whose center coincides with laser light emitted to the center of the virtual line segment of the laser light emitted from the optical unit. 3. The method according to claim 2, wherein
The image forming apparatus according to any one of items 1 to 6.