JP2011150005A - Optical device, image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical device in which thermal deformation is hardly caused in a substrate or a holding member thereof even when heat is generated in a polygon motor, thus the variation in an optical path and color shift is reduced. <P>SOLUTION: A seat part 50 is interposed between a polygon motor substrate 10 to which the polygon motor 12 is provided for rotatively driving a polygon mirror 11 and a polygon motor substrate holding member 20 which holds the polygon motor substrate 10. A compression spring 40 is provided between the substrate 10 and the flange 32 of a stepped screw 30 and the male screw part 31 of the stepped screw 30 is screwed in the female screw part 21 of the holding member 20; thus the substrate 10 is elastically pressurized against the holding member 20 with a predetermined distance. The cylindrical part 60 of the polygon motor 12 projected from the back side of the substrate 10 is fitted to the cylindrical reception hole 61 of the holding member 20; thus the substrate 10 is positioned to the holding member 20 centering on the rotary shaft 11a of the polygon mirror 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical device and an image forming apparatus that are mounted on an image forming apparatus that uses electrophotographic technology.

  An optical device mounted on an image forming apparatus using electrophotographic technology is generally composed of a polygon mirror that deflects light rays from a light source toward a scanned object such as a photosensitive drum, and the polygon mirror is driven to rotate. A polygon motor, a substrate on which the polygon motor is provided, an apparatus housing for supporting these, and the like. In such an optical device, the heat generation of the polygon motor including the bearing causes thermal deformation in the device housing such as the substrate, and the optical path of each color changes by changing the positional relationship of the optical components such as the polygon mirror and the lens. As a result, a problem of color misregistration occurs.

  To solve such a problem, the polygon mirror unit that generates heat and the driver board necessary to move the polygon mirror are fixed to a metal member with little thermal deformation, and the optical components other than the polygon scanner unit are installed in the device casing. There is an optical scanning device having a structure that is not in direct contact (see, for example, Patent Document 1).

  Further, in a configuration in which a plurality of deflection scanning means (polygon mirrors, motors) are arranged in parallel, the optical box is fixed to the frame of the image forming apparatus between two adjacent deflection scanning means of the bottom surface of the optical box. There is a scanning optical device provided with a fixing portion for this purpose (for example, see Patent Document 2).

  Furthermore, there is a polygon motor unit in which heat dissipation means (heat conducting material, fins) for radiating heat from a heat generating portion (bearing) of the polygon motor is provided in the polygon motor unit (see, for example, Patent Document 3).

  Furthermore, in the optical box, an optical scanning provided with a fixing portion for fixing to the frame of the image forming apparatus at a relatively low rigidity portion away from the corner near the outer shape apex of the bottom portion having a relatively high rigidity. There is an apparatus (for example, refer to Patent Document 4).

JP 2008-191254 A Japanese Patent Laid-Open No. 2004-226884 JP 2001-242408 A JP 2000-180766 A

  In each of the conventional techniques described in Patent Documents 1-4, basically, the substrate on which the polygon motor is provided and the holding member that holds the substrate are completely fixed. However, while the substrate is generally made of iron, the holding member is often made of resin when pursuing cost and made of aluminum when priority is given to heat dissipation. For this reason, in most cases, the substrate and the holding member, which are made of different materials having different linear expansion coefficients, are fastened.

  That is, both the substrate and the holding member try to expand due to the heat generated by the rotation of the polygon motor, but the substrate and the holding member made of different materials having different linear expansion coefficients are fastened. As a result, the substrate and the holding member are warped, and there is a problem that color misregistration occurs due to changes in the mounting posture of the polygon motor and the optical member.

  The present invention has been made paying attention to such problems, and even when heat is generated in the polygon motor, the substrate and its holding member are unlikely to be thermally deformed, thereby reducing optical path change and color misregistration. An object is to provide an apparatus and an image forming apparatus.

In order to solve the above problems, an optical device of the present invention comprises the following components a to e.
a) A polygon motor that is arranged coaxially with the rotation axis of a polygon mirror that deflects light rays in the direction of the scanning object, and that has a cylindrical portion on its outer shape to rotationally drive the polygon mirror.
b) A polygon motor board provided with a polygon motor.
c) A polygon motor substrate holding member for holding the polygon motor substrate.
d) A positioning unit for positioning the polygon motor substrate with respect to the polygon motor substrate holding member about the rotation axis of the polygon mirror.
e) An elastic member that holds the polygon motor substrate by elastically pressing the polygon motor substrate against the polygon motor substrate holding member.
In this optical apparatus, the polygon motor substrate is held by being elastically pressed against the polygon motor substrate holding member by the elastic member. That is, the polygon motor substrate is only held elastically pressed by the polygon motor substrate holding member, and is completely fixed to the polygon motor substrate holding member by screws or the like as in the prior art. Not held in.
In addition, the positioning unit positions the polygon motor substrate with respect to the polygon motor substrate holding member about the rotation axis of the polygon mirror.
For this reason, for example, even if the polygon motor substrate is made of general iron, the polygon motor substrate holding member is made of aluminum or resin, and the substrate and the substrate holding member are made of different materials having different linear expansion coefficients. The polygon motor substrate and the polygon motor substrate holding member expand radially independently from each other about the rotation axis of the polygon mirror (coaxial with the positioning portion) due to heat generated by the rotation of the polygon motor. That is, this optical device has a structure in which the expansion of the polygon motor substrate and the polygon motor substrate holding member due to the heat generated by the polygon motor do not affect each other. As a result, thermal deformation is unlikely to occur in the polygon motor substrate and the polygon motor substrate holding member.
The elastic member is not specified as long as the polygon motor substrate can be elastically pressed against the polygon motor substrate holding member. For example, in addition to the compression spring (coil spring) described in the following embodiment, A member having elasticity such as a leaf spring or rubber can be used.
In this optical apparatus, the positioning part is a cylindrical part of the polygon motor and a cylindrical receiving part that is formed on the polygon motor substrate holding member in the direction of the rotation axis of the polygon mirror and fits the cylindrical part of the polygon motor. A cylindrical receiving portion for positioning the polygon motor substrate with respect to the polygon motor substrate holding member about the rotation axis of the polygon mirror by inserting the cylindrical portion of the polygon motor into the cylindrical receiving portion; It is preferable to comprise.
When the polygon motor substrate is held on the polygon motor substrate holding member by having the cylindrical receiving portion on the polygon motor substrate holding member, the positioning portion is fitted with the cylindrical portion of the polygon motor. By fitting the cylindrical portion of the motor, the polygon motor substrate can be positioned with respect to the polygon motor substrate holding member around the rotation axis of the polygon mirror.
The positioning unit may include rotation direction positioning means for preventing rotation of the polygon motor substrate about the rotation axis of the polygon mirror and positioning the polygon motor substrate about the rotation axis of the polygon mirror. preferable.
Since the positioning unit has the rotation direction positioning means, the polygon motor substrate can be positioned with respect to the polygon motor substrate holding member around the rotation axis of the polygon mirror, and the rotation axis of the polygon mirror of the polygon motor substrate can be centered. It is also possible to prevent the rotation.
For example, the rotation direction positioning means includes a protrusion provided on the polygon motor substrate side and protruding in the radial direction of the cylindrical portion of the polygon motor, and a protrusion provided on the polygon motor substrate holding member side and attached to the protrusion. And a mounting groove.
Alternatively, the rotation direction positioning means is provided on the polygon motor substrate side or the polygon motor substrate holding member side in addition to the one constituted by the projection and the projection mounting groove, and is arranged in a radial direction around the rotation axis of the polygon mirror. The formed oval hole is fixed to the polygon motor substrate side or the polygon motor substrate holding member side and is attached to the oval hole so that the polygon motor substrate is fixed to the polygon motor substrate holding member by a predetermined distance. And an engaging member (for example, a stepped screw of the following embodiment) that is held and held.
According to the above configuration, the engagement member is mounted in the oval hole even when a relative positional shift due to heat generation occurs between the polygon motor substrate side and the polygon motor substrate holding member side during mounting. Therefore, the oval hole is displaced with respect to the engaging member at the engaging member portion, and the relative positional deviation can be absorbed, and the polygon motor substrate side and the polygon motor substrate holding member side can be absorbed. It is possible to avoid warping between them.
Such rotation direction positioning means may include only one of the protrusion and the protrusion mounting groove and the one having the oval hole, but it includes both. It doesn't matter.
Furthermore, the optical device includes a plurality of engaging members, and any one of them is located at a position closer to the positioning portion or farther from the positioning portion than the other engaging members. It may be provided.
The above-described optical device can be applied to an image forming apparatus including a copying machine, a printer, a facsimile, or a complex machine of these.

According to the present invention, even when the polygon motor substrate and the polygon motor substrate holding member are made of materials having different linear expansion coefficients, the polygon motor substrate and the polygon motor substrate holding member are centered on the rotation axis of the polygon mirror. While maintaining both positioning states, the heat generated by the rotation of the polygon motor can be independently expanded radially about the rotation axis of the polygon mirror (since each expansion does not affect each other). Therefore, it is difficult to cause thermal deformation such as relative warping due to the polygon motor substrate and the polygon motor substrate holding member fixed due to the heat generated by the polygon motor, thereby providing an optical device with little optical path change and color shift.
Further, when the polygon motor substrate is held by the polygon motor substrate holding member, the polygon motor substrate is held by the polygon motor substrate holding member by fitting the cylindrical portion of the polygon motor substrate to the cylindrical receiving portion of the polygon motor substrate holding member. The member can be easily positioned around the rotation axis of the polygon mirror.
Furthermore, as described above, the polygon motor substrate can be positioned with respect to the polygon motor substrate holding member around the rotation axis of the polygon mirror, and also prevented from rotating around the rotation axis of the polygon mirror of the polygon motor substrate. be able to.

1 is an external perspective view of an optical device according to an embodiment. It is an external appearance perspective view in the state where the outside dustproof cover of the optical device was removed. It is an external appearance perspective view of the whole principal part of the optical apparatus. It is an expanded sectional view of the stepped screw part of the optical device. It is a perspective view which shows the back side of a polygon motor board | substrate in the principal part of the same optical apparatus. It is a perspective view which shows the front side of the polygon motor board | substrate holding member in the principal part of the same optical apparatus. It is a perspective view which shows the back side of the polygon motor board | substrate holding member of the state which hold | maintained the polygon motor board | substrate in the principal part of the same optical apparatus. It is a perspective view which shows the back side of the polygon motor board | substrate which has a cylindrical part of another form in the principal part of the same optical apparatus. It is a perspective view which shows the back side of the polygon motor board | substrate holding member which has a cylindrical receiving hole of another form in the principal part of the same optical apparatus. It is a perspective view which shows the front side of the polygon motor board | substrate which has an elliptical screw insertion hole in the principal part of the same optical apparatus. FIG. 2 is a cross-sectional view of a color printer that is an example of an image forming apparatus including the optical device.

First, the outline of the image forming apparatus X according to the embodiment of the present invention will be described. The image forming apparatus X will be described here using a color printer as an example, but is not limited thereto, and may be a copier, a facsimile, a monochrome printer, or the like.
As shown in FIG. 11, the image forming apparatus X includes four image forming units 101, two optical devices 102, and an intermediate transfer belt 103 in the same manner as a general intermediate transfer type image forming apparatus. . Further, a secondary transfer device 104, a paper feeding device 105, a fixing device 106, a paper discharge unit 107, and the like are provided.
Here, the four image forming units 101 execute an image forming process for transferring toner images of respective colors of black, yellow, cyan, and magenta to the intermediate transfer belt 103, and the right side (intermediate transfer belt in FIG. 1). 103 in the order of black, yellow, cyan, and magenta. These image forming processes of the image forming unit 101 are not different for each color, but have the same configuration, and hence are collectively referred to as an image forming unit 101.
The image forming unit 101 includes a photosensitive drum 111 that carries a toner image (an embodiment of the image carrier), a charging device that charges the surface of the photosensitive drum 111, and laser beam light on the charged surface of the photosensitive drum 111. A developing device for developing an electrostatic latent image written by irradiation (exposure) with toner, a primary transfer device for transferring a toner image developed and formed on the photosensitive drum 111 to the intermediate transfer belt 103, and a photosensitive drum A cleaning device or the like for removing toner remaining on 111 is provided.
The two optical devices 102 are arranged below the image forming unit 101, and one of them is a laser beam L (beam light) for writing an electrostatic latent image on the photosensitive drum 111 for black and yellow. The other) outputs the laser beam L for writing the electrostatic latent image to the photosensitive drum 111 for cyan and magenta. The configuration of the optical device 102 will be described later.
The intermediate transfer belt 103 is an endless belt made of a material such as rubber or urethane, for example. The intermediate transfer belt 103 is wound around a driving roller 131 and a driven roller 132 and is driven to rotate. Pass between transfer devices.

The image forming operation on the transfer material such as recording paper by the image forming apparatus X is not particularly different from that of the general image forming apparatus X, and the outline thereof is a photosensitive drum that is first uniformly charged by the charging device. 111 is irradiated with the laser beam L by the optical device 102, so that the photosensitive drum 111 is exposed and an electrostatic latent image is written on the surface of the photosensitive drum 111. The electrostatic latent image is developed by a developing device, and a toner image is formed on the surface of the photosensitive drum 111. This is performed in the image forming unit 101 for each color.
The toner images formed on the surface of the photosensitive drums 111 of the respective colors are sequentially transferred and stacked on the intermediate transfer belt 103 by the respective primary transfer devices, and a full color toner image is formed on the intermediate transfer belt 103. The full-color toner image formed on the intermediate transfer belt 103 is transferred by the secondary transfer device 104 onto the recording paper fed one by one from the paper feeding device 105. Thereafter, the toner is fixed on the recording paper by the fixing device 106, and the recording paper on which the image is formed is discharged to the paper discharge unit 107.
After the toner image is transferred to the intermediate transfer belt 103, the toner remaining on the surface of the photosensitive drum 111 is removed by a cleaning device.
Thus, the image forming apparatus X forms a color image on a transfer material such as recording paper.

Hereinafter, the optical device 102 as an embodiment of the present invention used in the image forming apparatus as described above will be described in detail.
In FIG. 1 and FIG. 2 showing the optical device 102 according to this embodiment, an upper dustproof cover 2 is attached to the device casing 1, and the upper dustproof cover 2 is removed, as shown in FIG. Near the center of the housing 1 is located a polygon mirror 11 that deflects the light beam in the direction of a scanning object (not shown), and a polygon motor substrate 10 is disposed below the polygon mirror 11.
The main part of the optical device 102 has a structure as shown in FIGS.

3 to 7, the polygon motor substrate 10 is made of, for example, general iron, and a polygon motor 12 that rotates and rotates a rotation shaft 11 a that supports the polygon mirror 11 is provided on one end of the substrate 10. It is arranged on the same axis P as the rotating shaft 11a. In particular, as shown in FIG. 5, on the back side of the polygon motor substrate 10, a bearing portion 65 for accommodating a bearing (not shown) of the polygon motor 12 is provided concentrically with the coaxial P, and the polygon motor is provided. A cylindrical portion 60 that forms twelve outer shape portions protrudes in the direction of the alternate long and short dash line P coaxially with the rotating shaft 11 a of the polygon mirror 11. Of course, the bearing part 65 and the cylindrical part 60 are located concentrically.
Therefore, the polygon motor 12 is positioned with respect to the polygon motor substrate 10 by fitting the cylindrical portion 60 to the bearing portion 65 fixed to the polygon motor substrate 10.

  The polygon motor substrate holding member 20 that holds the polygon motor substrate 10 has a plate shape, and is made of, for example, aluminum having high thermal conductivity in order to emphasize heat dissipation. As shown in FIG. 6, on the front side of the polygon motor substrate holding member 20 (the holding side of the polygon motor substrate 10), the cylindrical portion 60 protruding from the back side of the polygon motor substrate 10 is slidable in the axial direction. A cylindrical receiving hole 61 is formed as an example of a cylindrical receiving portion to be inserted.

The cylindrical receiving hole 61 together with the cylindrical portion 60 of the polygon motor serves as a positioning portion for positioning the polygon motor substrate 10 with respect to the polygon motor substrate holding member 20 around the rotation axis 11a of the polygon mirror 11. It has an inner diameter that allows the cylindrical portion 60 of the polygon motor 12 to be fitted tightly enough to be detachable. Of course, the center of the cylindrical receiving hole 61 coincides with the rotation axis 11a of the polygon mirror 11 and the same axis P. However, the cylindrical receiving portion need not be the cylindrical receiving hole 61 (through hole), and may be a cylindrical receiving recess (groove).
It is desirable that the cylindrical receiving hole 61 is provided with a heat insulating material in order to prevent heat transfer from the polygon motor 12.

Thus, when the polygon motor substrate 10 is held by the polygon motor substrate holding member 20, the cylindrical portion 60 of the polygon motor substrate 10 is fitted into the cylindrical receiving hole 61 of the polygon motor substrate holding member 20. The polygon motor substrate 10 can be easily positioned with respect to the polygon motor substrate holding member 20 around the rotation axis 11a of the polygon mirror 11.
Note that a heat sink 25 is provided integrally on the back side of the polygon motor substrate holding member 20 in order to further improve heat dissipation. Further, the polygon motor substrate holding member 20 may be made of resin in order to reduce the cost.

As apparent from FIGS. 3 to 4, stepped screws 30 are provided at four locations as engaging members for holding the polygon motor substrate 10 to the polygon motor substrate holding member 20 at a predetermined distance. Here, as shown in FIG. 3, for example, the stepped screw 30 is provided at three locations near the polygon motor 12 (the rotating shaft 11 a of the polygon mirror 11) and at one location away from the polygon motor 12. The stepped screw 30 has a shape as shown in FIG. 4 and includes a male screw portion 31 (the screw groove is not shown in detail in the drawing) and a flange 32 that separates the screw head from the male screw portion 31. Have.
As apparent from FIG. 5, corresponding to the stepped screws 30, circular screw insertion holes 13 through which the stepped screws 30 are inserted are formed at four positions of the polygon motor substrate 10. As apparent from FIGS. 4 and 4, the screw insertion hole 13 has a larger diameter than the male screw portion 31 of the stepped screw 30, and the male screw portion 31 of the stepped screw 30 is inserted into the screw insertion hole 13. In this case, an appropriate clearance is generated between the screw insertion hole 13 and the stepped screw 30. Also, female screw portions 21 into which the male screw portions 31 of the stepped screws 30 are screwed are formed at corresponding four positions of the polygon motor substrate holding member 20.

Further, a seat portion 50 in contact with the polygon motor substrate 10 is formed around the female screw portion 21 of the polygon motor substrate holding member 20. The seat portion 50 has an insertion hole 51 through which the stepped screw 30 is inserted. The seat 50 is brought into contact with the polygon motor board 10 in a small area to minimize heat conduction from the polygon motor board 10 to the polygon motor board holding member 20, and to hold the polygon motor board 10 and the polygon motor board. This is to achieve holding the member 20 at a predetermined distance. The illustrated seat 50 is integral with the polygon motor substrate holding member 20, but may be a metal fitting such as a separate washer.
As shown in FIG. 6, the seat portion 50 may be fixed to the periphery of the female screw portion 21 on the front side of the polygon motor substrate holding member 20 with an adhesive or the like in advance, or may be screwed on the back side of the polygon motor substrate 10. It may be fixed around the hole 13.

  Furthermore, a compression spring 40 as an elastic member is interposed between the polygon motor substrate 10 and the flange 32 of the stepped screw 30. That is, one end of the compression spring 40 is engaged with the front side of the polygon motor substrate 10, and the other end is engaged with the flange 32 of the stepped screw 30. The compression spring 40 presses the polygon motor board 10 toward the seat 50, the polygon motor board 10 is fixed in the axial direction of the polygon motor 12, and is relatively free in the radial direction of the polygon motor 12. It is kept floating so that it can be moved to.

  In this embodiment, the stepped screw 30 is inserted into the screw insertion hole 13 and the screw insertion hole 51 in a state where the polygon motor substrate 10 is pressed against the seat 50 integrated with the polygon motor substrate holding member 20 by the compression spring 40. , The male screw portion 31 is screwed into the female screw portion 21, whereby the polygon motor substrate 10 is held by the polygon motor substrate holding member 20 while maintaining a predetermined distance (thickness of the seat portion 50).

In this embodiment, as described above, the cylindrical portion 60 of the polygon motor substrate 10 that is an element of the positioning portion is fitted into the cylindrical receiving hole 61 of the polygon motor substrate holding member 20 that is the same element. The polygon motor substrate 10 is positioned with respect to the polygon motor substrate holding member 20 around the rotation axis 11a of the polygon mirror 11.
Therefore, even if the polygon motor substrate 10 is made of general iron and the polygon motor substrate holding member 20 is made of aluminum (or resin) and both are made of different materials having different linear expansion coefficients, The motor substrate 10 and the polygon motor substrate holding member 20 maintain the positioning state of both about the rotation shaft 11a of the polygon mirror 11, and the rotation of the rotation shaft 11a of the polygon mirror 11 is caused by the heat generated by the rotation of the polygon motor 12. As a center, each expands radially independently.
As a result, warpage due to thermal deformation is less likely to occur between the polygon motor substrate 10 and the polygon motor substrate holding member 20 due to heat generated by the polygon motor 12, and optical path changes and color misregistration are suppressed.

In the optical device 102 including the main part configured as described above, the positioning unit further prevents the polygon motor substrate 10 from rotating about the rotation axis 11a of the polygon mirror 11 of the polygon motor substrate 10. You may provide the rotation direction positioning means which positions in the rotation direction of the polygon motor 12 centering on the rotating shaft 11a of the polygon mirror 11. FIG.
Specifically, the rotational direction positioning means includes, as an example, a protrusion 62 provided on the cylindrical portion 60 of the polygon motor substrate 10 as shown in FIG. 8 and a polygon motor substrate holding member 20 as shown in FIG. The protrusion mounting groove 63 is formed in the cylindrical receiving hole 61. The protrusion 62 has a streak shape protruding in the radial direction of the cylindrical portion 60, and the protrusion mounting groove 63 in which the protrusion 62 is mounted extends in the radial direction of the cylindrical receiving hole 61.
Since the positioning portion has the rotational direction positioning means (the projection 62 of the cylindrical portion 60 and the projection mounting groove 63 of the cylindrical receiving hole 61), the polygon motor substrate 10 is moved from the polygon motor substrate holding member 20 to the polygon mirror. In addition to positioning around the 11 rotation shafts 11a, rotation of the polygon mirror 11 of the polygon motor substrate 10 around the rotation shaft 11a can also be prevented.
That is, the polygonal motor substrate 10 rotates the polygon mirror 11 with respect to the polygon motor substrate holding member 20 by fitting the cylindrical portion 60 of the polygon motor substrate 10 into the cylindrical receiving hole 61 of the polygon motor substrate holding member 20. Although the screw insertion hole 13 of the polygon motor substrate 10 has a larger diameter than the male screw portion 31 of the stepped screw 30, the rotation shaft 11a of the polygon mirror 11 of the polygon motor substrate 10 is positioned. It is necessary to adjust the positioning in the rotation direction around the center. However, by having the rotational direction positioning means, positioning in the rotational direction around the rotational axis 11a of the polygon mirror 11 of the polygon motor substrate 10 can be easily performed.

  Alternatively, the rotation direction positioning means is provided on the polygon motor substrate 10 side or the polygon motor substrate holding member 20 side, except for the one constituted by the projection 62 and the projection mounting groove 63, and is centered on the rotation axis 11a of the polygon mirror 11. The oblong hole formed in the radial direction and fixed to the polygon motor substrate 10 side or the polygon motor substrate holding member 20 side and mounted in the oblong hole, the polygon motor substrate 10 is attached to the polygon motor substrate holding member. It may be configured to include an engaging member (the stepped screw 30) that is held at 20 with a predetermined distance.

  Specifically, as shown in FIG. 10, the rotational direction positioning means in this case includes one screw insertion hole 14 of the polygon mirror 11 out of four screw insertion holes 13 formed in the polygon motor substrate 10. An ellipse is formed in the radial direction around the rotation axis 11a. The width of the oval screw insertion hole 14 in the short axis direction (the direction perpendicular to the radial direction about the rotation shaft 11a) is larger than that of the male screw portion 31 when the stepped screw 30 of FIG. 4 is inserted. The upper part (see FIG. 4) is a size that fits closely, and the width in the major axis direction (radial direction centered on the rotating shaft 11a) is the male threaded part to ensure radial clearance. The dimension is sufficiently larger than the portion above 31.

By making one screw insertion hole 13 into an elliptical screw insertion hole 14, a stepped screw 30 is inserted into the screw insertion hole 14, and the male screw portion 31 is connected to the female screw portion of the polygon motor substrate holding member 20. When the screw 21 is screwed, rotation of the polygon mirror 11 of the polygon motor substrate 10 around the rotation shaft 11a can be prevented.
Further, the three screw insertion holes 13 have a larger diameter than the male screw portion 31 of the stepped screw 30 inserted therethrough, and a clearance is formed between the stepped screw 30 and an elliptical screw insertion hole. 14, the width of the polygon motor 12 in the rotational direction (the short axis direction) is substantially the same as that of the male screw portion 31 of the stepped screw 30, thereby positioning the polygon mirror 11 of the polygon motor substrate 10 around the rotational axis 11a. It can be set only by the size of the oval screw insertion hole 14, which can contribute to cost reduction.
The rotation direction positioning means may be provided with only one of the protrusion 62 and the protrusion mounting groove 63 and the oblong screw insertion hole 14 or both. May be provided.

  In addition, in FIG. 10, of the four screw insertion holes 13 and 14 through which the stepped screw 30 is inserted, the oval screw insertion hole 14 is more positioned than the other screw insertion holes 13 (that is, polygons). The distance between the mirror 11 and the rotating shaft 11a) is close (in the drawing, it is shown at the same distance as the two screw insertion holes 13). Of course, based on the above reasons, the screw insertion hole 14 at the upper right in FIG.

  The optical apparatus according to the present invention can be applied to an image forming apparatus including a copying machine, a printer, a facsimile machine, a multi-function machine thereof.

DESCRIPTION OF SYMBOLS 10 Polygon motor board | substrate 11 Polygon mirror 11a Rotating shaft 12 of polygon mirror Polygon motor 13 Screw insertion hole 14 Oval screw insertion hole (rotation direction positioning means)
20 Polygon motor board holding member 30 Stepped screw (engagement member)
40 Compression spring (elastic member)
50 Seat 60 Cylindrical part 61 Cylindrical receiving hole (cylindrical receiving part)
62 Protrusion (rotation direction positioning means)
63 Protrusion mounting groove (rotating direction positioning means)
102 Optical device P Coaxial with the rotation axis of the polygon mirror

Claims (9)

A polygon motor that is arranged coaxially with the rotation axis of a polygon mirror that deflects the light beam in the direction of the scanned object, and that has a cylindrical portion on its outer shape to rotationally drive the polygon mirror;
A polygon motor board provided with the polygon motor;
A polygon motor substrate holding member for holding the polygon motor substrate;
A positioning unit for positioning the polygon motor substrate with respect to the polygon motor substrate holding member about the rotation axis of the polygon mirror;
And an elastic member that holds the polygon motor substrate by elastically pressing the polygon motor substrate against the polygon motor substrate holding member.   The positioning portion is formed in the columnar portion of the polygon motor and the polygon motor substrate holding member in the rotation axis direction of the polygon mirror, and the columnar receiving portion into which the columnar portion of the polygon motor is fitted. The cylindrical motor substrate is inserted into the cylindrical receiving portion so that the polygon motor substrate is centered about the rotation axis of the polygon mirror with respect to the polygon motor substrate holding member. The optical device according to claim 1, further comprising a cylindrical receiving portion for positioning.   The positioning unit includes rotational direction positioning means for preventing the polygon motor substrate from rotating about the rotation axis of the polygon mirror and positioning the polygon motor substrate about the rotation axis of the polygon mirror. The optical device according to claim 1 or 2.   The rotation direction positioning means is provided on the polygon motor substrate side and protrudes in the radial direction of the cylindrical portion of the polygon motor, and is provided on the polygon motor substrate holding member side and is provided with the protrusion. The optical device according to claim 3, further comprising a mounting groove.   The rotation direction positioning means is provided on the polygon motor substrate side or the polygon motor substrate holding member side, and has an oval hole formed in a radial direction around the rotation axis of the polygon mirror, and the polygon motor substrate. And an engagement member that is fixed to the polygon motor substrate holding member side and is attached to the oblong hole to hold the polygon motor substrate to the polygon motor substrate holding member at a predetermined distance. The optical device according to claim 3.   6. The optical apparatus according to claim 4, comprising either or both of the rotational direction positioning means according to claim 4 and the rotational direction positioning means according to claim 5.   The optical apparatus according to claim 5, comprising a plurality of the engaging members, and any one of them is provided at a position closer to the positioning portion than the other engaging members.   The optical apparatus according to claim 5, comprising a plurality of the engaging members, and any one of them is provided at a position farther from the positioning portion than the other engaging members.   An image forming apparatus comprising the optical device according to claim 1.

Images