JP2010243747A - Scanning optical device and manufacturing method thereof - Google Patents

Abstract

A scanning optical device having a favorable laser spot shape over the entire scanning region and a method for manufacturing the same are provided by effectively correcting the tilt of the rotating shaft of a rotating polygon mirror by a simple method.
A deflector 4 for deflecting a laser beam 11 irradiated from a light source 1, a scanning lens 7 for imaging a deflected beam 12 deflected by the deflector 4 on a surface to be scanned, and the deflector 4 are accommodated. The optical box 10 includes a plurality of deflector seat surfaces 10a having the same height to which the deflector 4 is fixed, and at least one lower height than the deflector seat surface 10a. A sub-seat surface 10b is projected.
[Selection] Figure 1

Description

  The present invention relates to a scanning optical apparatus used for writing an image on a photoreceptor such as a laser printer and a digital copying machine using an electrophotographic process, and a method for manufacturing the same.

  2. Description of the Related Art Conventionally, there has been a scanning optical device that scans a photosensitive member that reflects and deflects modulated light modulated by image data with a rotary polygon mirror and forms an image by an electrophotographic system via an imaging optical system. This scanning optical device is required to have a very fine and uniform laser spot shape over the entire scanning area in order to obtain a high-definition and uniform image density on the photosensitive member.

  As a factor for deteriorating the laser spot shape, the rotation of the rotary polygon mirror is known to be tilted. In view of this, there has been proposed a shaft tilt correction method in which the tilting direction of the rotating shaft is displayed in advance on the driving motor of the rotary polygon mirror, and the driving motor is fixed so that this is a direction insensitive to spot shape deterioration. (See Patent Document 1).

JP 2006-171561 A

  However, in the conventional example, since the driving motor for the rotary polygon mirror is fixed at an arbitrary angle, it is difficult to connect a power source or a harness for supplying a driving signal. In addition, it is necessary to make the shape of the drive motor substantially circular or square so as not to collide with peripheral components such as a scanning lens and a laser light source, and it is possible to secure a space for mounting a drive circuit for driving the drive motor. It becomes difficult.

  In addition, a separate process for displaying the axis tilt direction in advance with the rotating polygon mirror unit alone is required, which increases the number of steps. When the rotary polygon mirror unit is assembled, the axis tilt changes depending on the component accuracy and the assembly accuracy, so that there is a situation in which accurate assembly cannot be performed only with the axis tilt direction measured in advance.

  The technical problem of the present invention has been made in view of the above circumstances, and its purpose is to effectively correct the tilting of the rotating shaft of the rotary polygon mirror by a simple method, and to cover the entire scanning area. A scanning optical apparatus having a good laser spot shape and a method for manufacturing the same are provided.

  To achieve the above object, a typical configuration according to the present invention includes a deflector that deflects a laser beam emitted from a light source, and a scan that forms an image on the surface to be scanned on the laser beam deflected by the deflector. In a scanning optical device comprising a lens and an optical box that accommodates the deflector, a plurality of deflector seat surfaces of the same height to which the deflector is fixed project from the optical box, At least one sub-seat surface having a height lower than that of the deflector seat surface is protruded.

  A deflector for deflecting the laser beam emitted from the light source; a scanning lens for forming an image of the laser beam deflected by the deflector on a surface to be scanned; and an optical box for housing the deflector. In the scanning optical device, a plurality of deflector seat surfaces of the same height to which the deflector is fixed are projected from the optical box, and at least one sub seat surface is projected, and the sub seat surface Has a fragile portion having substantially the same height as the deflector seat surface.

  A deflector that deflects the laser beam emitted from the light source; a scanning lens that forms an image of the laser beam deflected by the deflector on a surface to be scanned; and an optical box that houses the deflector. The optical box is provided with a plurality of deflector seat surfaces having the same height to which the deflector is fixed, and at least one sub seat surface having a height lower than that of the deflector seat surface. In the manufacturing method of the scanning optical device, the step of measuring the tilting direction of the rotating shaft of the deflector fixed to the optical box, and the sub-seat surface opposite to the tilting direction of the rotating shaft of the deflector And a step of fixing the deflector to the selected sub-seat surface.

  A deflector that deflects the laser beam emitted from the light source; a scanning lens that forms an image of the laser beam deflected by the deflector on a surface to be scanned; and an optical box that houses the deflector. The optical box is provided with a plurality of deflector seat surfaces having the same height to which the deflector is fixed, and at least one sub seat surface projecting, the sub seat surface comprising the deflector In a method of manufacturing a scanning optical device having a weakened portion having substantially the same height as a seating surface, a step of measuring a tilt direction and a tilt amount of a rotating shaft of the deflector fixed to the optical box, The step of selecting the sub-seat surface opposite to the direction of tilting of the rotating shaft, and the amount of tilting of the rotating shaft of the deflector on the sub-seat surface selected by the deflector become a predetermined amount or less. And a step of tightening and fixing the screw.

  According to the present invention, the tilting of the rotating shaft of the rotary polygon mirror is effectively corrected by a simple method, and a good laser spot shape can be obtained over the entire scanning area.

It is a perspective view explaining the scanning optical apparatus which concerns on Embodiment 1 of this invention. It is a top view of the scanning optical apparatus shown in FIG. (a), (b) is a figure explaining the assembly process of the scanning optical apparatus of FIG. (a), (b) is a figure explaining the mode of an assembly of the scanning optical apparatus of FIG. It is a perspective view of the sub bearing surface which concerns on Embodiment 2 of this invention. (a), (b) is a figure explaining the mode of an assembly of the scanning optical apparatus concerning Embodiment 2 of this invention.

[Embodiment 1]
Hereinafter, the scanning optical apparatus according to the first embodiment of the present invention will be described in detail with reference to the drawings. 1 is a perspective view of the scanning optical device, and FIG. 2 is a plan view of the scanning optical device.

  1 and 2, the scanning optical apparatus has an optical box 10, in which a laser light source 1, an anamorphic lens 2, an optical diaphragm 3, a scanning lens 7, a folding mirror 8, a laser drive circuit board 9 and a deflector. 4 is housed. The deflector 4 includes a scanner motor 6 and a polygon mirror 5 that is a rotating polygon mirror that rotates about a rotation shaft 6 a of the scanner motor 6.

  The optical box 10 has a pair of deflector seat surfaces 10 a protruding from the polygon mirror 5 and a pair of sub seat surfaces 10 b protruding from the polygon mirror 5. Specifically, the pair of sub-seat surfaces 10b are arranged so that a straight line 22 passing through the center thereof is substantially parallel to an angle bisector formed by the laser beam 11 incident on the deflector 4 and the optical axis 21 of the scanning lens 7. The pair of deflector seat surfaces 10a are arranged such that a straight line 23 passing through the center thereof is substantially perpendicular to the straight line 22. A through hole (not shown) is formed at a position facing the deflector seat surface 10a and the sub seat surface 10b.

  The height of the sub seat surface 10b is slightly lower than that of the deflector seat surface 10a, and pilot holes for female screws or tapping screws are provided in the deflector seat surface 10a and the sub seat surface 10b. A screw 14 is fastened to the pilot hole of the deflector seat surface 10a, and a screw 15 is fastened to the pilot hole of the sub seat surface 10b. The deflector 4 is fixed to the optical box 10. However, the screw 15 is fastened after one of the pair of sub-seat surfaces 10b is selected depending on the direction in which the rotating shaft 6a of the scanner motor 6 is tilted.

  Next, the operation of the scanning optical device will be described. That is, the laser drive circuit board 9 emits a laser beam 11 that blinks in response to an image signal from a controller (not shown).

  This laser beam 11 is converted by the anamorphic lens 2 into a parallel beam or a convergent beam having a desired convergence rate in the main scanning direction, and a beam formed on the reflecting surface 5a of the polygon mirror 5 in the sub-scanning direction. After that, the optical diaphragm 3 limits the beam width to a desired value and makes it incident on the reflecting surface 5 a of the polygon mirror 5.

  The polygon mirror 5 is rotationally driven by the scanner motor 6, and the laser beam 11 becomes a deflected beam 12 by the reflection surface 5 a of the polygon mirror 5. The deflected light beam 12 passes through the scanning lens 7, is changed in direction by the folding mirror 8, and then is scanned and imaged on a surface to be scanned outside the scanning optical device to form a scanning line 13.

  Further, a part of the deflected light beam 12 passes through the anamorphic lens 2 again, enters a photosensor (not shown) mounted on the laser drive circuit board 9, and generates a synchronization signal. In this case, the anamorphic lens 2 has a form in which two lens portions are integrally formed, one of which is arranged in the optical path from the laser light source 1 to the polygon mirror 5, and the other is from the polygon mirror 5 to the photosensor. It is arranged in the optical path between.

  Next, correction of the axis tilt of the deflector 4 when manufacturing the scanning optical device will be described with reference to FIG. FIG. 3 schematically shows an assembling process of the deflector 4, and is a cross-sectional view with a straight line 22 connecting the centers of the sub-seat surfaces 10b as a cutting line.

  In FIG. 3A, reference numeral 31 denotes an assembly tool. The optical box 10 is fixed to the assembly tool 31 with high accuracy, and the laser autocollimator 32 is attached with high accuracy.

  The laser autocollimator 32 includes a light source 32a, a half mirror 32b, a lens 32c, and an area sensor 32d. The laser light emitted from the light source 32a is converted into a parallel light beam by the lens 32c, and is irradiated onto the upper surface 5b of the polygon mirror 5 and reflected therefrom. The light is imaged on the area sensor 32d through the lens 32c and the half mirror 32b. Then, the inclination of the polygon mirror 5 is measured by measuring the position of the imaging point on the area sensor 32d by a processing device (not shown).

  When assembling the deflector 4 to the optical box 10, the optical box 10 is first fixed on the assembly jig 31, and then the deflector 4 is installed on two deflector seat surfaces 10 a of the optical box 10 and screwed. Fix with 14. Next, the scanner motor 6 of the deflector 4 is driven to rotate, and the upper surface 5 b of the polygon mirror 5 is measured by the laser autocollimator 32.

  Here, when the upper surface 5b of the polygon mirror 5 has a surface shake, the image on the area sensor 32d becomes an annular image 33 as shown in FIG. 3B, and the rotation shaft 6a of the scanner motor 6 is rotated. The inclination is the center 34 of the annular image 33. Then, the tilting direction of the rotating shaft 6a in the plane including the straight line 22 perpendicular to the main scanning plane and connecting the centers of the two sub-seat surfaces 10b is detected.

  FIG. 4 (a) shows a case where the tilting direction of the rotating shaft 6a obtained by measurement is counterclockwise. In this case, as shown in FIG. 4 (b), the screw 15 is screwed and fastened to the sub-seat surface 10b1 on the side opposite to the direction in which the rotating shaft 6a is tilted to correct the tilting of the rotating shaft 6a. If the rotation direction of the rotating shaft 6a is clockwise, the screw 15 is screwed into the sub-seat surface 10b2 for correction.

  The tilt of the rotating shaft 6a of the scanner motor 6 that can be corrected is only the inclination in the plane including the straight line 22 connecting the centers of the two sub-seat surfaces 10b (10b1, 10b2), but it is highly resistant to the deterioration of the laser spot shape. What contributes is the direction of the bisector of the angle formed by the laser beam 11 incident on the deflector 4 and the optical axis of the scanning lens 8.

  For this reason, the sub-seat surface 10b is arranged in the direction of the bisector, and the deflector seat surface 10a is arranged in a direction orthogonal to the direction of the bisector, so that the rotation shaft 6a can be effectively tilted. It can be corrected.

  Further, in this embodiment, since it is not necessary to rotate the assembly direction of the scanner motor 6, it is easy to connect a harness for supplying power and drive signals. Or it is not necessary to make it into a square shape. Furthermore, since the axis tilt when the deflector 4 is assembled to the optical box 10 is measured, the axis tilt direction can be accurately grasped.

  Therefore, the tilting of the rotating shaft 6a of the scanner motor 6 is corrected by a simple process, and a scanning optical device having a good laser spot shape can be obtained.

  In this embodiment, two deflector seat surfaces 10a are provided. However, when the scanner motor 6 has a flat and substantially rectangular shape, the deflector seat surface 10a is separated from the deflector seat surface 10a and the sub seat surface 10b in order to suppress vibration. Other seating surfaces may be provided at different positions.

  As mentioned above, although embodiment of this invention was explained in full detail, this invention is not limited to the said embodiment description, In the range which does not deviate from the mind of the invention described in the claim of this invention, Various changes can be made.

[Embodiment 2]
For example, FIG. 5 shows a perspective view of the sub seat surface 10b according to the second embodiment. The sub seat surface 10 b includes a circular bottom surface 41, a screw hole 42, and a plurality of protrusions 43. The height of the bottom surface 41 is formed lower than that of the deflector seat surface 10a, and the screw hole 42 is formed substantially at the center of the bottom surface 41. The plurality of protrusions 43 are formed so that the height thereof is substantially the same as that of the deflector seat surface 10 a, and are protruded from the outer peripheral portion of the bottom surface 41 at intervals.

  FIG. 6A shows a state in which the deflector 4 is installed in the optical box 10, the screw 14 is fastened to the deflector seat surface 10a, and the screw 15 is not fastened to the sub seat surface 10b. In this case, since the projection 43 of the sub seat surface 10b and the deflector seat 10a are substantially the same height, the scanner motor 6 is in contact with the projection 43.

  In this state, the assembly tool 31 is used to detect the direction in which the rotating shaft 6a of the scanner motor 6 falls and the amount of fall in that direction. Then, the screw 15 is tightened into the sub seating surface 10b opposite to the direction in which the rotating shaft 6a falls. At this time, the screw 15 is tightened while measuring the tilting amount of the rotary shaft 6a, and the tightening is finished when the tilting amount is zero or within a desired range. At that time, as shown in FIG. 6 (b), the protrusion 43 collapses in response to the tightening amount of the screw 15, and the deflector 4 can be fixed in a desired posture.

  Thus, according to this embodiment, it is possible to adjust steplessly so that the amount of tilting of the rotating shaft 6a is not more than a predetermined amount, and a scanning optical device with a better laser spot shape can be obtained. In the present embodiment, the plurality of protrusions 43 protrude from the bottom surface 41. However, it is only necessary to provide a weak portion that is crushed by the fastening force of the screw 15. For example, a thin annular protrusion is provided on the bottom surface 41. Also good.

DESCRIPTION OF SYMBOLS 1 Laser light source 4 Deflector 5 Polygon mirror 6 Scanner motor 6a Rotating shaft 7 Scanning lens
10 Optical box
10a Deflector seat
10b Sub bearing surface
11 Laser beam
12 Deflection beam
31 Assembly tool
43 Projection

Claims (9)

A scanning device comprising: a deflector that deflects a laser beam emitted from a light source; a scanning lens that forms an image of the laser beam deflected by the deflector on a surface to be scanned; and an optical box that houses the deflector. In an optical device,
A plurality of deflector seat surfaces having the same height to which the deflector is fixed project from the optical box, and at least one sub seat surface having a height lower than the deflector seat surface is projectingly provided. A scanning optical device. A straight line connecting the centers of the two sub-seat surfaces is substantially parallel to the bisector of the angle formed by the laser beam emitted from the light source and the optical axis of the scanning lens, and the two deflector seats 2. The scanning optical apparatus according to claim 1, wherein the scanning optical apparatus is substantially perpendicular to a straight line passing through the center of the surface. The scanning optical device according to claim 1, wherein the deflector includes a rotary polygon mirror and a motor that rotationally drives the rotary polygon mirror. A scanning device comprising: a deflector that deflects a laser beam emitted from a light source; a scanning lens that forms an image of the laser beam deflected by the deflector on a surface to be scanned; and an optical box that houses the deflector. In an optical device,
A plurality of deflector seat surfaces having the same height to which the deflector is fixed project from the optical box, and at least one sub seat surface projects, and the sub seat surface includes the deflector seat. A scanning optical device having a fragile portion having substantially the same height as a surface. The scanning optical apparatus according to claim 4, wherein the fragile portion is a plurality of protrusions. A straight line connecting the centers of the two sub-seat surfaces is substantially parallel to the bisector of the angle formed by the laser beam emitted from the light source and the optical axis of the scanning lens, and the two deflector seats 6. The scanning optical apparatus according to claim 4, wherein the scanning optical apparatus is substantially perpendicular to a straight line passing through the center of the surface. The scanning optical device according to claim 4, wherein the deflector includes a rotary polygon mirror and a motor that rotationally drives the rotary polygon mirror. A deflector that deflects a laser beam emitted from a light source, a scanning lens that forms an image of the laser beam deflected by the deflector on a surface to be scanned, and an optical box that houses the deflector, The optical box is provided with a plurality of deflector seat surfaces having the same height to which the deflector is fixed, and at least one sub seat surface having a height lower than the deflector seat surface. In the method of manufacturing an optical device,
Measuring a tilt direction of a rotation axis of the deflector fixed to the optical box; selecting a sub-seat surface opposite to a tilt direction of the rotation axis of the deflector; and Fixing to the selected sub-seat surface, and a method for manufacturing a scanning optical device. A deflector that deflects a laser beam emitted from a light source, a scanning lens that forms an image of the laser beam deflected by the deflector on a surface to be scanned, and an optical box that houses the deflector, A plurality of deflector seat surfaces having the same height to which the deflector is fixed project from the optical box, and at least one sub seat surface projects from the optical box, and the sub seat surface includes the deflector seat surface. In the manufacturing method of the scanning optical device having the fragile portion of substantially the same height,
Measuring a tilt direction and a tilt amount of a rotating shaft of the deflector fixed to the optical box, selecting the sub-seat surface opposite to a tilt direction of the rotating shaft of the deflector, and And a step of tightening and fixing a screw on the selected sub-seat surface so that the tilting amount of the rotation shaft of the deflector is not more than a predetermined amount. Method.