JPH09197332A - Light deflector and its assembling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and highly accurately correct the tilt of a rotary polygon mirror. SOLUTION: Ring-like correcting projections 74, 76 are concentrically formed on the flange 58 of a rotor 48 to which a rotary polygon mirror 44 is to be fixed. Each of the projections 74, 76 has prescribed rotational oscillation quantity and tilts the fixed mirror 44 at a different angle. Clearance grooves 84, 86 are respectively formed on the end faces 80, 82 of the mirror 44 correspondingly to the projections 74, 76 so that the mirror 44 can be put on either one of the projections 74, 76. Plane tilt amount of the mirror 44 is measured and the mirror 44 is put on either one of the projections 74, 76 which can generate a tilt approximately equivalent to the measured plane tilt amount. Consequently, the plane tilt amount of the mirror 44 assembled on the rotor 48 can be suppressed to a small value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical deflector, and more particularly to an optical deflector for deflecting a light beam by a rotating polygonal mirror.

[0002]

2. Description of the Related Art Generally, in a digital copier, a digital printer or the like, when an image is formed on a recording medium such as paper, a light beam emitted from a light source such as a semiconductor laser is deflected. A scanning surface such as the surface of the photoconductor is scanned by the deflected light beam to form an electrostatic latent image on the surface of the photoconductor.
The formed electrostatic latent image is then developed by a developing device, transferred onto a recording medium by a transfer device, and then fixed by a fixing device (a so-called electrophotographic process) to form a digital image. It

By the way, as described above, as an optical deflector for deflecting the light beam from the light source toward the photoconductor,
There is one that deflects and reflects a light beam by a rotating polygon mirror (polygon mirror) that rotates at a high speed in one direction. According to this type of optical deflector, since a plurality of mirror surfaces (reflection surfaces) formed on the outer periphery of the rotary polygon mirror can sequentially deflect the light beam to scan the surface of the photoconductor or the like line by line, high speed scanning is possible. There are advantages such as less scanning unevenness.

However, since the conventional optical deflector has a structure in which the rotary polygon mirror is directly mounted on a rotatable flat pedestal, the amount of surface tilt of the rotary polygon mirror itself (with respect to the end surface (mounting surface) of the rotary polygon mirror) There is a problem that the reflecting surface of the rotating polygon mirror after assembly may fall due to an error in the perpendicularity of the reflecting surface) or the inclination of the upper surface of the pedestal to which the rotating polygon mirror is attached. When the rotating polygon mirror tilts, the light beam reflected by the reflecting surface of the rotating polygon mirror is periodically displaced in the direction (sub scanning direction) perpendicular to the deflection scanning direction (main scanning direction) by the reflecting surface and sub scanning. Unevenness occurs in the direction, and the quality of the formed image is degraded.

In order to prevent the rotary polygon mirror from tilting, Japanese Patent Laid-Open No. 2-176715 proposes an optical deflecting device in which an adjusting member for adjusting the tilt of the rotary polygon mirror is interposed between the rotary polygon mirror and the pedestal. Has been done. But with this proposal,
Since the tilt of the rotary polygonal mirror is adjusted at one point, the adjustment work is extremely complicated when two or more reflecting surfaces of the rotating mirror are opposed to each other, and fine adjustment cannot be performed. Moreover, since it is necessary to perform the adjustment after the rotary polygon mirror is mounted on the pedestal, the adjustment work is extremely troublesome also in this respect.

Particularly in recent years, in order to reduce the number of rotations and the load of the drive motor for rotating the rotary polygon mirror, it has been attempted to increase the number of reflecting surfaces with a small (small diameter) rotary polygon mirror. However, if the number of reflecting surfaces of the rotating polygon mirror is increased, the swing angle of the light beam reflected by each reflecting surface becomes smaller, and the optical path length between the rotating polygon mirror and the photoconductor must be lengthened. Even if there is a slight tilt, the position of the light beam on the photoconductor is largely displaced in the sub-scanning direction. As described above, the tilting of the rotary polygon mirror has been an obstacle to realizing a highly reliable optical deflector.

The present invention has been made in consideration of the above facts, and an object of the present invention is to obtain an optical deflector capable of correcting tilting of a rotary polygon mirror extremely easily and with high accuracy.

[0008]

In order to achieve the above object, the invention according to claim 1 has a pedestal that rotates, and a rotary polygonal mirror that is coaxially mounted on the pedestal and that rotates integrally. In the optical deflector, a support means is provided which projects from the mounting surface of the pedestal to which the rotary polygon mirror is mounted and which causes the rotary polygon mirror to tilt differently.

According to the first aspect of the invention, the supporting means for causing the rotary polygon mirror to tilt differently from the mounting surface of the rotating body is projected. Since the rotary polygon mirror has a surface tilt amount based on its processing accuracy, if the rotary polygon mirror is mounted on the support means so that the surface tilt amount of the rotary polygon mirror is canceled by the support means, the rotary polygon after mounting The tilt amount of the mirror disappears, and the reflecting surface of the rotating polygon mirror is kept substantially parallel to the rotation axis.

In the invention according to claim 1, the supporting means may be constituted by a plurality of annular projections provided concentrically around the rotation axis of the pedestal as in claim 2. As described in No. 3, three or more protrusions may be provided on each of a plurality of circular orbits drawn concentrically around the rotation axis of the pedestal. In this way, if multiple projections with different distances from the rotation axis are prepared, one projection (projection at a predetermined distance from the rotation axis) corresponding to the amount of surface tilt of the rotary polygon mirror is selected, and the selected projection is selected. The tilt of the rotary polygon mirror can be reduced simply by mounting the rotary polygon mirror on top.

As the supporting means, a single spiral protrusion as described in claim 4 may be used in addition to the one constituted by a plurality of protrusions as described above.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, a rotary polygon mirror is provided at a predetermined position on the supporting means on a mounting surface of the rotary polygon mirror to the rotating body. It is characterized in that a convex portion for supporting is formed.
According to the invention of claim 5, it is possible to support the rotary polygon mirror at a predetermined position on the support means (for example, a position corresponding to the amount of surface tilt of the rotary polygon mirror) only by placing the rotary polygon mirror on the pedestal. You can

According to a sixth aspect of the invention, in the fifth aspect of the invention, the convex portions are formed on both axial end faces of the rotary polygon mirror. If convex portions are formed on both end faces of the rotary polygon mirror, the position on the support member on which the rotary polygon mirror is supported (that is, the tilt amount of the rotary polygon mirror) can be changed simply by turning the rotary polygon mirror over and attaching it. Therefore, even if there are variations in the amount of surface tilt of the rotary polygon mirror, it is possible to mount the rotating polygon mirror in accordance with the amount of surface tilt.

According to a seventh aspect of the present invention, when the rotary polygon mirror is coaxially assembled on the rotating pedestal, different tilt amounts are generated in the rotary polygon mirror on the mounting surface of the pedestal on which the rotary polygon mirror is mounted. Supporting means is provided, an area on the supporting means that causes the amount of tilt substantially equal to the amount of surface tilt of the rotary polygon mirror is selected, and the rotary polygon mirror is supported on the selected area. To do.

According to the seventh aspect of the present invention, the plane tilt of the rotary polygon mirror can be achieved only by selecting a region on the support means corresponding to the amount of plane tilt of the rotary polygon mirror and supporting the rotary polygon mirror in the selected region. Since it is possible to correct the error, it is extremely easy to correct the trouble. Moreover, by selecting an area on the supporting means, even if the amount of surface tilt of the rotary polygon mirror varies, it can be supported in an area corresponding to the amount of surface tilt.

According to an eighth aspect of the invention, in the seventh aspect of the invention, before the rotary polygon mirror is supported on the area of the selected supporting means, the area other than the selected area is deleted or deformed. It is characterized by According to the invention described in claim 8, even when the mounting surface of the rotary polygon mirror is flat, the rotary polygon mirror can be easily and reliably supported on the predetermined region of the support member.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] FIG. 1 shows a state in which an optical deflector according to a first embodiment of the present invention is applied to a digital printer. The digital printer 10 is connected to an information processing device such as a workstation or a computer (not shown) via a cable, and records an image on a recording medium such as paper based on an image signal input from the information processing device. Has become. As shown in FIG. 1, the recording sheet 3
The photoconductor drum 12 is rotatably provided on the delivery path 0. A charger 1 is provided on the outer peripheral side of the photosensitive drum 12.
4, the developing device 16 and the transfer charging device 20 are arranged in this order, and the drum surface between the charging device 14 and the developing device 16 is irradiated with a light beam from the scanning optical device 18.

The scanning optical device 18 includes a laser diode 32 used as a light source, an optical deflector 34 for deflecting a laser beam (light beam) LB from the laser diode 32 toward the photoconductor, and various optical systems. The laser diode 32 is on / off controlled based on an image signal input line by line from the information processing device, and emits a laser beam LB modulated according to the image signal. The laser beam LB emitted from the laser diode 32 reaches the rotary polygon mirror 44 of the optical deflector 34 via the collimator lens 38 and the cylinder lens 40. The rotating polygon mirror 44 is formed in a regular polygonal column shape and has a plurality of reflecting mirror surfaces 60 on the outer circumference. The laser beam LB that has reached the rotary polygon mirror 44 is reflected by the reflecting mirror surface 60 of the rotary polygon mirror 44, and then is imaged on the photosensitive drum 12 via the fθ lens 42.

The rotary polygon mirror 44 is also rotated at a high speed by a drive motor 46. For this reason, the laser beam LB incident on the rotary polygon mirror 44 is deflected at a predetermined swing angle by the movement of the reflecting mirror surface 60 accompanying the rotation of the rotary polygon mirror 44, and the laser beam LB is moved along the line direction (axial direction) on the drum surface. Scan (main scan). At this time, the surface of the photoconductor drum 12 has already been uniformly charged by the charger 14, and an electrostatic latent image having a reduced potential is formed on the surface of the photoconductor drum 12 according to the pattern of the image to be recorded. To be done.

Toner is attached to the electrostatic latent image formed on the surface of the photoconductor drum 12 by the developing device 16 to make it visible, and then it is superposed on the recording paper 30. In this state,
The toner image on the photosensitive drum 12 is transferred onto the recording paper 30 by the electrostatic force from the transfer charger 20. The toner image transferred onto the recording paper 30 is then transferred to the fixing device 28.
Heat or pressure is applied by the heat treatment to fix the fusion.

A cleaner 26 is also provided on the outer peripheral side of the photosensitive drum 12 to remove the toner remaining on the surface of the photosensitive drum 12. The drum surface from which the residual toner has been removed is again subjected to a series of processes such as charging, exposure, and development described above, and an image is recorded on the recording sheet 30 that is conveyed at any time.

FIG. 2 shows a schematic structure of an optical deflector 34 applied to the scanning optical device 18. Optical deflector 3
4 is a rotating body 4 rotatably supported by a housing 50.
8, a rotary polygon mirror 44 mounted on the rotating body 48 and rotating integrally with the rotating body 48, a drive motor 46 provided between the rotating body 48 and the housing 50 to rotate the rotating body 48 in a predetermined direction, Is equipped with. The housing 50 has a plate shape and is detachably attached to the casing of the scanning optical device 18 (not shown). A cylindrical support portion 50A is formed in the center of the housing 50 so as to penetrate the housing 50. The rotating body 48 has a cylindrical rotating shaft portion 52, and a disc-shaped flange (base) 58 extending radially outward from the outer periphery of the rotating shaft portion 52. The portion of the rotary shaft portion 52 below the flange 58 is the support portion 50.
A is inserted in the inner peripheral side of A, and the bearing 54 is provided in the supporting portion 50A.
It is rotatably supported via A and 54B. The bearings 54A and 54B are arranged to face each other with a predetermined gap, and a preload spring 56 is provided between the bearings 54A and 54B. The preload spring 56 eliminates the radial clearance between the bearings 54A and 54B and applies a preload to the bearings 54A and 54B in the axial direction.

The rotary polygon mirror 44 is detachably mounted on the flange 58 of the rotary body 48. The rotary polygon mirror 44 has a regular octagonal prism shape, and a reflecting mirror surface 60, which is mirror-finished, is formed on each side surface of the octagon. A through hole 62 penetrating along the axial direction is formed in the central portion of the rotary polygon mirror 44, and the rotary polygon mirror 44 can be concentrically mounted on the flange 58 by fitting the rotary polygon mirror 44 on the outer circumference of the rotary shaft portion 52. It is like this.

The rotary polygon mirror 4 is provided on the upper end of the rotary shaft 52.
A pressing plate 64 is attached to press 4 toward the flange 58 (downward). The pressing plate 64 is the rotary shaft 52.
It is fitted in a groove formed on the outer circumference of the rotary polygon mirror 4
4 is held between the pressing plate 64 and the flange 58. The pressing force of the pressing plate 64 is determined within a range in which the rotary polygon mirror 44 does not shift due to rotation without deforming the rotary polygon mirror 44 (that is, so that the flatness of the reflecting surface 60 is kept good). To be done.

The drive motor 46 includes a drive coil 68 mounted circumferentially on the outer periphery of the upper end of the support 50A.
A drive magnet 70 is arranged on the outer peripheral side of the drive coil 68 so as to face each other with a predetermined gap. The drive coil 68 is mounted on the control board 7 on the housing 50.
The energization is controlled by a control device (not shown) connected to the control board 72 and mounted on the control board 72. The drive magnet 70 is
It is attached to the inner surface side of a bent portion 66 formed on the outer peripheral edge of the mounting flange 58, and rotates the rotating body 48 by controlling the energization of the drive coil 68.

By the way, the rotary polygon mirror 44 itself has a surface tilt (end faces 80, 82 of the rotary polygon mirror 44) based on processing accuracy.
Error in the squareness of the reflecting mirror surface 60 relative to the reflecting mirror surface 60 of the rotating polygon mirror 44 after being mounted on the flange 58.
The tilt also occurs at 0, and the laser beam LB reflected by the rotary polygon mirror 44 shifts in the sub-scanning direction, resulting in uneven pitch in the sub-scanning direction. In the first embodiment, in order to reduce the pitch unevenness as described above, a substantially annular correction projection (supporting means) 7 is provided on the flange 58 to which the rotary polygon mirror 44 is attached.
4 and 76 are formed in concentric circular projections, and correction projections 74 and 7 are formed.
The rotary polygon mirror 44 is mounted on any one of the protrusions 6.

Here, the upper and lower end surfaces (mounting support surfaces) 80 and 82 of the rotary polygon mirror 44 are provided with relief grooves 84 and 86, respectively.
Are formed. The escape groove 84 is formed in an annular shape in a region of the end face 80 of the rotary polygonal mirror 44 facing the correction protrusion 76, so to speak, a convex portion is seated (contacted) on the protrusion 74 on the end face 80 of the rotary polygonal mirror 44. It has a formed structure. The escape groove 86 is formed in a circular shape in a region of the end face 82 of the rotary polygon mirror 44 facing the protrusion 74, and a convex portion for seating (contacting) on the protrusion 76 is formed on the end face 82 side of the rotary polygon mirror 44. It has a structure. In this way, if the convex portions are formed on the upper and lower end surfaces 80, 82 of the rotary polygon mirror 44 corresponding to the protrusions 74, 76, the rotary polygon mirror 44 can be mounted on the different projections 74, 76 only by turning it over. It becomes possible (see FIG. 4).

On the other hand, the sectional shape of each portion in the circumferential direction of the correction projections 74, 76 is rectangular or trapezoidal, and the upper surfaces 74A, 76A of the correction projections 74, 76 are respectively the rotary polygon mirror 44.
It is used as a seating surface for seating. Of the correction protrusions 74, 76, the upper surface 76A of the protrusion 76 on the outer peripheral side is
The rotary polygon mirror 44 is formed with a profile that causes a relatively small tilt, and the upper surface 74 of the protrusion 74 on the inner peripheral side is formed.
A is formed so as to cause a relatively large tilt of the rotary polygon mirror 44. Therefore, the correction protrusions 74 and 76
One of the projections 74 and 76 that causes a tilt amount equivalent to the surface tilt amount α (see FIG. 5) of the rotary polygon mirror 44 is selected, and the rotary polygon mirror 44 is mounted on the selected projections 74 and 76. If it is placed, the influence of the surface tilt amount α of the rotary polygon mirror 44 can be canceled by the correction projections 74 and 76.

The tilt amount of the rotary polygon mirror 44 when placed on the correction projections 74 and 76 is determined by the rotational runout of the upper surfaces of the correction projections 74 and 76 (the direction of the rotation axis that occurs when the rotating body 48 is rotated ( It can be grasped by measuring the deflection in the vertical direction). That is, when the rotary polygon mirror 44 is placed on the correction projections 74 and 76 and rotated, the rotary polygon mirror 44 is rotated.
Causes a tilt (runout) of a size determined by the support span (diameter D of each projection 74, 76) and the runout width γ of the rotary runout. Therefore, if the swing width γ on the correction projections 74 and 76 is measured, the tilt of the rotary polygon mirror 44 caused by the correction projections 74 and 76 is determined from the relationship with the diameter D of the correction projections 74 and 76. You can know the size.

6A and 6B show the correction projection 74,
An example of a difference in the tilt amount of the rotary polygon mirror 44 due to 76 is shown. In this example, the rotary polygon mirror 44 has a larger deflection when mounted on the inner peripheral projection 74 than when mounted on the outer peripheral projection 76. The vertical axis in FIGS. 6A and 6B indicates the projections 7
A value (converted value) β obtained by converting the rotational shake widths on 4 and 76 into the tilt (tilt) of the rotary polygon mirror 44 is shown, and the horizontal axis shows the positions of the correction projections 74 and 76 in the circumferential direction.

The characteristics of the correction projections 74 and 76 as shown in FIG. 6 can be obtained, for example, as follows. Rotating body 4
8 is processed by a processing machine (for example, a lathe), FIG.
As shown in (A), the outer periphery of the flange 58 of the rotating body 48 is gripped and rotated by the chuck 200 of the processing machine. At this time, the tips of the projections previously projected from the flange 58 are simultaneously machined by a tool 202 such as a cutting tool so that the correction projections 7
I get 4,76. When the rotating body 48 thus obtained is rotatably supported on the housing 50, the rotating center 204 is assembled to the rotation center 204 during processing as shown in FIG. 7B due to the processing accuracy and the assembly accuracy of the rotating body 48 itself. Center of rotation 206 after attachment
However, the rotational runout width of the correction projection 74 and the rotational runout width of the correction projection 76 after assembly can be made substantially equal. Therefore, when the rotary polygon mirror 44 is mounted on the correction projections 74 and 76 and rotated, the amount of tilt (tilt) that occurs in the rotary polygon mirror 44 is the diameter of the correction projections 74 and 76 (distance from the rotation shaft 206). As described above, the tilting of the rotary polygon mirror 44 is larger when it is mounted on the inner peripheral projection 74 than when it is mounted on the outer peripheral projection 76.

Next, a method of assembling the optical deflector 34 will be described with reference to FIG.
This will be described with reference to FIG. The solid line in FIG. 8 shows the state at a predetermined rotation angle, and the chain double-dashed line shows the state rotated by 180 ° from the solid line state. Prior to assembling the optical deflector 34, first, the amount .alpha. Of surface tilt of the rotary polygon mirror 44 used is measured. At this time, as shown by the solid line in FIG. 8A, the light beam from the light source is directed upward (one side in the direction vertical to the optical scanning direction).
When the inclination reflected on the mirror is +, and the inclination reflected on the lower side is −, as indicated by the chain double-dashed line in FIG.
The surface tilt amount α of A to 60H is sinusoidal as a whole as shown in FIG. Next, the measured surface tilt amount α is the maximum α
_A marking is formed at a position corresponding to the reflecting mirror surface 60C that becomes the _MAX . Here, as shown in FIG. 2B, markings (marks or the like) 90 are formed in the radial direction at positions near the reflecting mirror surface 60C of the end faces 80 and 82 of the rotary polygon mirror 44.

The end faces 80 and 82 of the rotary polygon mirror 44 are marqueeed.
Once the ring 90 is formed, the rotor 50 is then attached to the housing 50.
48 is rotatably supported. Then, as shown in FIG.
Rotate the rotating body 48 around the rotating shaft 206
Rotational runout on the upper surface of the positive projections 74, 76 (in the rotation axis direction)
The shake amount) γ is measured. Deflection on the correction projections 74 and 76
When the amount γ is measured, then the measured shake amount γ is
_MINMarking 92 as shown in FIG.
Form. At this time, the correction projections 74 and 76 are as described above.
And the shake amount γ on the correction projections 74 and 76
Have the same period and phase as each other. For this reason,
As shown in (B), mark the flange 58 on the upper surface at one place in the circumferential direction.
If the braking 92 is formed, the swing amount of both pedestals 74 and 76
γ is the minimum γ _MINCan be specified.

When the markings 90 and 92 are formed on the rotary polygon mirror 44 and the flange 58, respectively, next, any one of the correction projections 74 and 76 corresponding to the maximum surface tilt amount α _MAX measured as described above is selected. To do. For example, when the maximum surface tilt amount α _MAX is relatively large as shown in FIG.
When the protrusion 74 on the inner circumferential side that causes a relatively large tilt as shown in FIG. 5A is selected, and when the maximum surface tilt amount α _MAX is relatively small as shown in FIG. The protrusion 76 on the outer peripheral side shown is selected.

When any one of the correction projections 74 and 76 is selected, the rotary polygon mirror 4 is placed on the selected projections 74 and 76.
Place 4. FIG. 2 shows an example of mounting in the case where the amount of surface tilt α of the rotary polygon mirror 44 is relatively large, and the end face 80 of the rotary polygon mirror 44 faces downward so that the rotary polygon mirror 44 is fitted to the outer peripheral side of the rotary shaft portion 52 to rotate. The polygon mirror 44 is mounted on the inner protrusion 74. Further, FIG. 4 shows an example of mounting when the surface tilt amount α of the rotary polygon mirror 44 is relatively small.
4 is placed on the outer protrusion 76 by fitting the outer end side 82 of the No. 4 face down on the outer peripheral side of the rotary shaft 52.

After the rotary polygon mirror 44 is placed on the projections 74 and 76, the rotary polygon mirror 44 is rotated to mark 9
The positions of 0 and 92 are made to coincide with each other, and in this state, the rotary shaft 52
The pressing plate 64 is attached to the upper end portion of and the rotary polygon mirror 44 is fixed. As a result, the influence of the surface tilt amount α of the rotary polygon mirror 44 is canceled by the rotational shake of the correction projections 74 and 76, and each reflecting mirror surface 60 of the rotary polygon mirror 44 is shown in FIG.
As shown in (C), it is kept substantially parallel to the rotary shaft 206.

As described above, in the first embodiment, the annular correction projection 7 for causing the rotary polygon mirror 44 to be tilted differently is provided on the flange 58 to which the rotary polygon mirror 44 is attached.
Since a plurality of projections 4 and 76 are formed, one of the projections 74 and 76 corresponding to the amount of surface tilt α of the rotary polygon mirror 44 is formed.
The rotary polygon mirror 44 can be assembled with a minimum amount of tilting simply by mounting it on the upper surface.
It is possible to keep 0 substantially parallel to the rotation axis 206. Therefore, the deviation of the light beam LB reflected from each reflecting mirror surface 60 of the rotary polygon mirror 44 in the sub-scanning direction, that is, the pitch unevenness in the sub-scanning direction can be reduced as much as possible, and a highly reliable optical deflector can be obtained. Obtainable.

Further, by preparing a plurality of correction projections 74 and 76 for causing different tilts of the rotary polygon mirror 44, one correction projection 74 corresponding to the surface tilt amount α of the rotary polygon mirror 44, Select 76 and select the selected protrusions 74, 76.
Simply attach the rotating polygon mirror 44 to the
Since the tilt of the rotary polygon mirror 44 can be greatly reduced, the tilt of the rotary polygon mirror 44 can be reduced very easily.

In particular, when the reflecting mirror surface 60 of the rotary polygon mirror 44 is processed, a plurality of rotary polygon mirrors 44 are formed as shown in FIG.
Since they are processed at a time in a stacked state, the surface tilt amount α of the rotary polygon mirror 44 differs depending on the processing lot, the stacking position, and the like. Even in such a case, if a plurality of correction projections 74 and 76 are prepared as in the present embodiment, the optimum projection 7 can be provided in accordance with the variation in the surface tilt amount α for each processing lot.
It becomes possible to mount it on 4,76.

Further, in the first embodiment, the rotary polygon mirror 4
4, markings 90 and 92 are respectively formed at the position corresponding to the maximum surface tilt amount α _MAX and the position corresponding to the minimum rotational runout amount γ _MIN of the mounting flange 58.
Since the rotary polygon mirror 44 is attached so that the positions of 92 coincide, the rotary polygon mirror 44 can be easily attached on the flange 58 also in this respect.

In the first embodiment, the escape grooves 84, 8 are formed in the upper and lower end surfaces 80, 82 of the rotary polygon mirror 44.
6 is formed so that the rotary polygon mirror 44 can be selectively mounted on the correction projections 74 and 76. However, a groove is formed only on one end surface 80, 82 of the rotary polygon mirror 44 and the predetermined projections 74, 7 are formed.
It may be configured to be mounted on the table 6. However, the rotating polygon mirror 4
If grooves 84 and 86 are formed on the upper and lower end surfaces 80 and 82 of 4, the rotary polygon mirror 44 can be mounted on the rotary body 48 by reversing the mounting, so that the different projections 74 and 76 can be mounted. Even if there is variation in α, it can be dealt with well.

Further, in the first embodiment, a plurality of correction projections 74, 8 are provided on the flange 58 of the rotating body 48.
Although 6 is formed, a single protrusion may be used. In short, the rotating body 4
It suffices that the tilting amount of the rotary polygon mirror 44 varies depending on the distance from the rotation axis of 8. Therefore, instead of the correction protrusions 74 and 76, for example, a single spiral protrusion having a substantially spiral shape around the rotation axis may be used.

Further, in the first embodiment, the rotating body 4
Although the annular correction protrusions 74 and 76 are formed on the flange 58 of No. 8, a plurality of columnar protrusions may be formed as shown in FIG. In the example of FIG. 11, circular orbits 110A to 110A drawn concentrically on the flange 58 centering on the rotation axis.
Three correction projections 112 and 1 on 110C, respectively.
14 and 116 are formed at every predetermined angle (120 °).

Further, in the first embodiment, when the rotary polygon mirror 44 is assembled on the flange 58, the marking 90 is attached to the portion where the surface tilt amount α of the rotary polygon mirror 44 becomes the maximum α _MAX, and the correction projection. The rotational shake amount γ of 74 and 76 is the minimum γ
_{Although the} markings 92 are formed on the areas where _MIN is reached, on the contrary, even if the markings 90 and 92 are applied to the areas where the amount of surface _tilt α is minimum α _MIN and the amount of rotational shake γ is maximum γ _MAX , respectively. Good. [Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIGS. 9 and 10. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. As shown in FIGS. 9 and 10, in the optical deflector 100 according to the second embodiment, a plurality of annular correction projections 102 to 106 are concentrically formed on the flange 58 of the rotating body 48 (here, three are provided). ) Formed, these correction projections 102 to
The rotary polygon mirror 44 is mounted on any one of the correction projections 106 (the innermost projection 1 in the figure).
02 is shown mounted).

Here, the upper and lower end surfaces 8 of the rotary polygon mirror 44
Nos. 0 and 82 are flat, and the escape groove as in the first embodiment is not formed. In addition, the correction projections 102 to 1
06 is made of a resin that can be easily processed,
Prior to the mounting of No. 4, the unused protrusions 102 and 104 are previously removed by a cutting tool such as a nipper or a cutter, or deformed by applying heat or the like.

According to the second embodiment, the annular correction projections 102 to 106 are concentrically formed on the flange 58 of the rotating body 48, and the correction projections 102 to 106 are formed.
Since any one of the projections is selected and the rotary polygon mirror 44 is mounted on the selected projection, the surface tilt of the rotary polygon mirror 44 is corrected easily and with high accuracy as in the first embodiment. can do.

Further, since the correction projections 102 to 106 are made of resin and the projections other than the selected projections are deleted or deformed, even if there is a projection that hinders the mounting of the rotary polygonal mirror 44, the rotary polygonal mirror 44 is provided. Can be easily mounted on the desired projection. Moreover, since it is possible to mount the rotary polygon mirror 44 without any processing on the end surface,
It is possible to prevent adverse effects associated with the processing of the rotary polygon mirror 44 and reduce the manufacturing cost of the rotary polygon mirror 44.

In the second embodiment, when the rotary polygon mirror 44 is mounted on the desired projections 102 to 106, a projection other than the target projection (a projection other than the projection corresponding to the amount of surface tilt of the rotary polygon mirror). ) Is deleted or deformed, but it may be attached on a predetermined protrusion via a sheet material or the like. Further, when the rotary polygon mirror 44 is mounted on the projections 102 to 106, if there is no projection that hinders the mounting, it is not necessary to delete or deform the projection.

[0049]

As described above, according to the first to fourth aspects of the invention, the supporting means for causing the rotary polygon mirror to tilt differently is projected from the mounting surface of the rotating body. It has an excellent effect that tilt of the rotary polygon mirror can be corrected easily and with high accuracy.

According to the fifth aspect of the present invention, since the convex portion is formed on the mounting surface of the rotary polygon mirror, the rotary polygon mirror can be mounted at a predetermined position on the support means only by mounting the rotary polygon mirror on the pedestal. This has an excellent effect that the work can be simplified and the work can be simplified.

According to the sixth aspect of the present invention, since the convex portions are formed on both end surfaces of the rotary polygon mirror, it is possible to satisfactorily cope with variations in the amount of surface tilt of the rotary polygon mirror. Have.

According to the seventh aspect of the invention, since the area tilt of the rotary polygon mirror can be corrected by selecting the area of the supporting means corresponding to the amount of surface tilt and fixing the rotary polygon mirror to the selected area. It has an excellent effect that tilt of the rotary polygon mirror can be corrected easily and with high accuracy.

According to the invention described in claim 8, there is an excellent effect that the manufacturing cost of the rotary polygon mirror can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a digital printer to which an optical deflector of the present invention is applied.

FIG. 2 is a schematic view showing a first embodiment of an optical deflector of the present invention, (A) is a front sectional view, and (B) is a plan view.

3A and 3B are views showing a rotating body applied to the optical deflector of FIG. 2, FIG. 3A is a partial front sectional view, and FIG. 3B is a partial plan view of the same.

FIG. 4 is a view showing a state in which a rotary polygon mirror is turned over and attached in the optical deflector of FIG.

FIG. 5 is a graph showing the amount of surface tilt of a rotating polygon mirror,
(A) shows a comparatively large amount of trouble, and (B) shows a smaller amount of trouble than (A).

6A and 6B are graphs in which the amount of rotational shake of the correction projection is converted into the amount of tilt of the rotary polygonal mirror, where FIG. 6A shows the converted value of the outer projection and FIG. 6B shows the converted value of the inner projection.

FIG. 7 is a diagram for explaining an example of a method of processing the upper surface of the correction protrusion.

FIG. 8 is a diagram for explaining a method of assembling the optical deflector shown in FIG.

9A and 9B are schematic views showing a second embodiment of the optical deflector of the present invention, FIG. 9A is a front sectional view, and FIG. 9B is a plan view.

10A and 10B are views showing a rotating body applied to the optical deflector of FIG. 9, where FIG. 10A is a partial front sectional view and FIG. 10B is a partial plan view of the same.

FIG. 11 is a diagram showing another configuration example of the correction protrusion.

FIG. 12 is a diagram showing a state in which a plurality of rotary polygon mirrors are stacked when processing the reflecting surface of the rotary polygon mirror.

[Explanation of symbols]

 18 Scanning Optical Device 34 Optical Deflector 44 Rotating Polygonal Mirror 48 Rotating Body 58 Flange (Pedestal) 60 Reflecting Mirror Surface 68 Drive Coil (Drive Motor) 70 Drive Magnet (Drive Motor) 74 Correction Protrusion (Support Means) 76 Correction Protrusion ( Supporting means) 80, 82 End surface (mounting support surface) 90, 92 Marking

Claims (8)

[Claims] 1. An optical deflector having a rotating pedestal and a rotary polygonal mirror mounted coaxially on the pedestal and rotating integrally, wherein the optical deflector is projected from a mounting surface of the pedestal to which the rotary polygonal mirror is mounted. An optical deflector characterized by comprising supporting means for causing different amounts of tilting of the rotary polygon mirror. 2. The optical deflector according to claim 1, wherein the supporting means comprises a plurality of annular projections provided concentrically around the rotation axis of the pedestal. 3. The optical deflector according to claim 1, wherein the supporting means is formed by providing three or more protrusions on a plurality of circular orbits concentrically drawn about the rotation axis of the pedestal. . 4. The optical deflector according to claim 1, wherein the supporting means is a spiral protrusion formed in a spiral around the rotation axis of the pedestal. 5. A mounting surface of the rotary polygon mirror to a rotating body,
The optical deflector according to claim 1, wherein a convex portion for supporting the rotary polygon mirror is formed at a predetermined position on the supporting means. 6. The optical deflector according to claim 5, wherein the convex portions are formed on both axial end faces of the rotary polygon mirror. 7. When coaxially assembling a rotary polygon mirror on a rotating pedestal, a support means is provided on a mounting surface of the pedestal to which the rotary polygon mirror is mounted, for causing different tilt amounts to the rotary polygon mirror. A set of optical deflectors, characterized in that a region on the support means that causes the amount of tilt substantially equal to the amount of surface tilt of the rotary polygon mirror is selected and the rotary polygon mirror is supported on the selected region. Attaching method. 8. The optical deflector according to claim 7, wherein regions other than the selected region are deleted or deformed before supporting the rotary polygon mirror on the region of the selected supporting means. Assembly method.