JPH10268225A - Adjusting method of optical deflection device and adjusting device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adjusting method and an adjusting device so as to improve the accuracy of a tilt angle of an optical deflection device using a polygon mirror. SOLUTION: This device is composed of a light source 301 irradiating the mirror surface 101A of a polygon mirror 101 and a light receiving element 302 receiving a reflected light beam from the mirror surface 101A, has a tilt angle adjusting means 400 composed of a tilt angle measuring instrument 300 for measuring the tilt angle of the mirror surface 101A and a pushing-up member 401A (B) acting in parallel with the axial direction of the polygon mirror 101 and, by measuring the tilt angle of the mirror surface 101 A and finely adjusting the tilt angle adjusting means 400 so as to decrease the variance of tilt angle of the mirror surface 101A, positional adjustment of the polygon mirror fitted over the outside cylinder 102 of the radial shaft is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for adjusting a light deflector used for writing an image in an image recording apparatus.

[0002]

2. Description of the Related Art In an image recording apparatus such as a laser beam printer, a laser beam is incident on a polygon mirror rotating at a high speed based on information read as writing means of the image, and the reflected light is scanned on the photosensitive member surface. The image is recorded by projection. FIG. 7 is a perspective view of a writing optical system to which the light deflecting device 100 is mounted. The output laser light from the semiconductor laser 1 becomes parallel light by the collimator lens 2 of the beam shaping optical system, passes through the first cylindrical lens 3 and is reflected and deflected by the polygon mirror 101 of the optical deflector 100. The beam is transmitted through the second cylindrical lens 5, subjected to beam correction, and projected on the photosensitive drum 6 via the reflecting mirror 5 at a predetermined spot diameter in the sub-scanning direction. Synchronization detection for each line
This is performed by causing the light beam before the start of scanning to enter the synchronization detector 8 via the mirror 7.

In such a scanning optical system, even a slight inclination angle error of the polygon mirror causes scanning unevenness on the screen, resulting in image distortion and degraded image quality. This becomes more remarkable by rotating the polygon mirror at a high speed to increase the recording density.

[0004] In the case of low-speed rotation, the polygon mirror is used directly fixed to the rotating shaft of the motor. However, in the case of high-speed rotation, the polygon mirror is fixed to the radial shaft outer cylinder and touches the radial shaft inner cylinder. The drive rotation is performed using an air bearing that rotates in a floating manner. The present applicant has disclosed a technology of an optical polarizing device having a dynamic pressure bearing in each specification such as Japanese Patent Application Laid-Open Nos. 7-243337, 7-259849, 8-114219 and 8-112471. FIG. 8 shows a cross-sectional configuration of an optical polarization device having a dynamic pressure bearing composed of an upper thrust plate 124, a lower thrust plate 123, and a radial shaft inner cylinder 125. In FIG. 8, the radial shaft inner cylinder 125 and the lower thrust plate 12
3 and a coil 126 constituting a static magnetic field of the motor are attached to form a dynamic pressure bearing unit 120. Further, a rotor 110 is constructed by concentrically assembling a ring-shaped magnet 106 for a rotating magnetic field, an outer ring portion 104 made of aluminum, a radial shaft outer cylinder 102 made of ceramic, a polygon mirror 101 and a mirror holder 103 concentrically. I have. After the rotor 110 is fitted into the radial shaft inner cylinder 125, the upper thrust plate 124 is fixed concentrically to the radial shaft 125. The radial shaft inner cylinder 125, the lower thrust plate 123 and the upper thrust plate 124, and the radial shaft outer cylinder 1
A gap S of about 3 to 10 μm is formed between the upper and lower surfaces and the inner peripheral surface of the fitting 02. When the rotor 110 rotates, the rotor 110 floats up in the air without touching the dynamic pressure bearing portion 120 and rotates smoothly. Is maintained.

[0005]

In order to obtain good image quality, it is necessary to reduce the tilt angle of the polygon mirror, and the machining accuracy of the polygon mirror, the rotor portion to which the polygon mirror is fixed, and the dynamic pressure bearing portion are reduced. In addition, the assembly processing accuracy must be particularly high.

Means for minimizing the angle of inclination of the polygon mirror depend on increasing the accuracy of each component and the accuracy of assembly as described above. It requires great skill and the production cost is very high. In addition, when the thermal expansion coefficients are different between parts, it is inevitably difficult to obtain stable accuracy and durability.

The present invention solves the above-mentioned problems of the prior art, and provides a high quality scanning image stably without particularly increasing the processing accuracy and assembly accuracy of each part. Another object of the present invention is to provide an adjustment method and an adjustment device for an optical deflection device, which can adjust, eliminate, and fix a tilt angle with respect to a radial shaft outer cylinder with extremely high accuracy.

[0008]

An object of the present invention is to fix a polygon mirror to a rotary shaft or a radial shaft outer cylinder before fixing the polygon mirror to a rotary shaft or a radial shaft outer cylinder.
An optical deflecting device comprising: measuring an inclination angle of each mirror surface of the polygon mirror with respect to the rotation axis or the radial axis outer cylinder; and adjusting an inclination of the polygon mirror in a direction to reduce variation in the inclination angle. An adjusting method, a light source for irradiating the mirror surface of the polygon mirror, a light receiving element for receiving reflected light from the mirror surface, and a tilt angle measuring device for measuring a tilt angle of the mirror surface; and an axial direction of the polygon mirror. A tilt angle adjusting means for a polygon mirror comprising a pushing member which operates in a pushing direction in parallel, and the tilt angle of each mirror surface are measured by the tilt angle measuring device, and the tilt angle adjustment is performed in a direction to reduce the variation of the tilt angle of the mirror surface. A controller for adjusting the means, and for adjusting the positional relationship of the polygon mirror extrapolated to the shaft portion or the radial shaft outer cylinder. It is achieved by the device.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Two embodiments of an adjusting device for an optical deflecting device according to the present invention will be described below.
However, the present invention is not limited to this.

(Embodiment 1) An adjusting device for an optical deflecting device according to Embodiment 1 will be described with reference to FIGS.

In this embodiment, a description will be given of an adjusting device for adjusting the inclination angle of a polygon mirror extrapolated to a radial shaft outer cylinder to adjust the inclination angle of each mirror surface of the polygon mirror to be extremely small. But
The adjustment is performed in exactly the same manner for the motor shaft part instead of the radial shaft outer cylinder.

The polygon mirror 101 is a regular polygonal polygon mirror made of pure aluminum or the like, and has a diagonal length of 30-8.
This is a member processed with high accuracy of about 0 mm and a thickness of about 3 to 12 mm near the shaft. The radial shaft outer cylinder 102 is a cylindrical member made of a material such as ceramic and has a length slightly longer than the thickness of the polygon mirror 101.
There is a gap S1 between the outer diameter of the radial shaft outer cylinder 102 and the inner diameter of the polygon mirror 101. This gap S1 is filled with an adhesive after being adjusted as described below, and becomes in a fixed state.

Reference numeral 201 denotes a shaft fixing means for fixing the radial shaft outer cylinder 102, by clamping both ends of the cylindrical radial shaft outer cylinder 102 and supporting the inner diameter, or by fixing the end face of the radial shaft outer cylinder 102. By suction, the radial shaft outer cylinder 10
2 is fixed. Reference numeral 202 denotes a support table which is rotatable about the central axis of the radial shaft outer cylinder 102. On the upper surface, the polygon mirror 101 extrapolated to the radial shaft outer cylinder 102 is mounted. FIG. 2 shows a state where the polygon mirror 101 is mounted. The polygon mirror 101 is supported on a support table 202 by three-point support. One of them is a fixed support portion 212 which supports the polygon mirror 101, which is supported at three points by suction or other means, so as not to cause slippage (positional displacement). The other two points are tilt angle adjusting means 400A and 40A which enable fine adjustment of the tilt angle of the polygon mirror 101 on the support table 202.
0B, the push pins 401A, 40A which come into contact with the polygon mirror 101 by the forward / reverse rotation of the motor M2A or M2B.
1B moves slightly in the vertical direction. A gear 202a is provided on the outer periphery of the support table 202, and the polygon mirror 101 is mounted on the gear G (M1) provided on the motor shaft by a gear 202a meshed through an intermediate gear by rotation of the motor M1. The placed support table 202 rotates.

Reference numeral 300 denotes a tilt angle measuring device for measuring each tilt of the mirror surface 101A of the polygon mirror 101 on the support table 202. Each measuring device 300 is polygon mirror 1
01, a light emitting unit 301 for irradiating the mirror surface 101A, and a mirror surface 1
The light-emitting portion 301 and the light-receiving portion 302 are provided in such a positional relationship as to be on the same plane as the central axis of the radial shaft outer cylinder 102. I have. The light emitting section 301 has a laser diode (LD) as a light emitting element and a lens provided on the front surface thereof, and a spot-shaped parallel light irradiates the mirror surface 101A. The light receiving unit 302 is, for example, a position sensitive detector in which light receiving elements are arranged in a line, and the light reflected from the mirror surface 101A at the position facing the light receiving unit 302 is received by the light receiving unit 3.
The tilt angle of the mirror surface 101A is measured according to the position where the light beam 02 is irradiated. At this time, the measurement accuracy can be increased by moving the light receiving unit 302 away from the mirror surface 101A.

In the adjusting device having the above-described structure, control is performed by an adjusting program of the light deflecting device included in the control unit 200 as a memory so as to minimize the variation in the tilt angle of the polygon mirror 101 between the polygon mirrors. You. Next, control by the adjustment program will be described.

The control unit 200 drives the motor M1 to rotate, thereby causing the support table 202 to rotate slowly.

The tilt angle measuring device 300 emits light toward the mirror surface 101A at a position directly facing the light emitting unit 301, and the reflected light is received by the light receiving unit 302 to measure the tilt angle. The measurement result by the light receiving unit 302 during one rotation of the support table 202 is, for example, in a state shown in FIG. The measurement points are indicated by circles in the figure. Although the figure shows the polygon mirror 101 having six mirrors, the number of mirrors is not limited to this number. Here, the control unit 200 detects a large mirror surface of most tilt angle and a small mirror of the most tilt angle in mirror, obtains the variation amount B _MAX of the maximum inclination angle.

Next, two inclination angle adjusting means 400A,
400B, for example, the inclination angle adjusting means 400
Rotated appropriate amount of motor M2A in one direction A, the push pin 401A is pressed member in a state where the push-up an appropriate amount to obtain the amount of variation B _MAX ¹ of the maximum inclination angle in one rotation of the support table 202. The control unit 200 compares the maximum variation B _MAX with the above-mentioned maximum variation B _MAX, and if B _MAX <B _MAX ¹ , the motor M2A
Is rotated in the opposite direction by an appropriate amount, and the push pin 401A is pushed down by an appropriate amount to obtain the maximum variation B _MAX ² during one rotation of the support table 202. B _MAX > B _MAX ²
If, further obtains the amount of variation B _MAX ³ of Rotate appropriate amount of motor M2A in the same direction, as compared with the previous variation amount B _MAX ^2, Note if B _MAX ^2> a B _MAX ^3, the motor M2A Is repeated in the same direction by an appropriate amount, and if B _MAX ² <B _MAX ³ , the push pin 4 that minimizes the maximum amount B _MAX ^N of variation in the tilt angle by repeating operations such as slightly rotating in the opposite direction.
The position of 01A is obtained. FIG. 3B shows the measurement result in this state.

Next, the control section 200 sets the inclination angle adjusting means 400 with the push pin 401A fixed at the above position.
B, rotate the motor M2B in one direction by an appropriate amount.
01B is pushed up by an appropriate amount.
The maximum variation B _MAX ^{N + 1} of the tilt angle during one rotation is obtained, compared with the maximum variation B _MAX ^N, and based on the comparison result, the push pin 401B is pushed up or down. In the same manner as described above, fine adjustment is gradually performed in the direction in which the variation of the maximum tilt angle becomes smaller, and the amount of the variation is set to the preset limit value B _AL.
Adjustment is completed when the value becomes smaller than. Also, the comparison and fine adjustment based on this maximum variation amount of the plurality of times, even when not less than a limit value B _AL previously set, press pin 401B is fixed to the position of the smallest amount of variation , Again the inclination angle adjusting means 4
Performing a fine adjustment by 00A, until the amount of variation B _MAX ^M of maximum inclination angle obtained is smaller than the limit value B _AL previously set to continue fine adjustment. FIG. 3C shows a measurement result at the time of completion of the adjustment.

When the adjustment until the amount of variation of the tilt angle becomes equal to or less than a preset limit value is completed, an adhesive is filled in a gap S1 between the polygon mirror 101 and the radial shaft outer cylinder 102, Integration with the adjusted state is performed.

The adjusting device of the first embodiment described above performs the fine adjustment of the tilt angle fully automatically by the control unit 200, but is configured to realize this through a manual operation in the middle of this process. It may be.

(Embodiment 2) An adjusting device for an optical deflecting device according to Embodiment 2 will be described with reference to FIGS. Here, members having the same functions as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. In the present embodiment, an adjustment device that adjusts the inclination angle of the polygon mirror extrapolated to the motor shaft to adjust the inclination angle of each mirror surface of the polygon mirror to be extremely small has been described. Adjustment of the radial shaft outer cylinder in place of the motor shaft portion is performed in exactly the same manner by separately providing a rotary drive member instead of the motor MO described below.

The motor MO is a drive motor capable of high-speed rotation. A polygon mirror 101 is inserted into a motor shaft 501 of the motor MO, and the distance between the motor shaft 501 and the inner diameter of the polygon mirror 101 is about 0.1 mm. There is a gap S2, and the gap S2 is filled with an adhesive such as an inorganic adhesive, and adjustment is performed in a semi-fixed state before the adhesive is fixed.

A marking 101B is provided on the upper surface of the polygon mirror 101, and a marking detecting means 502 is provided.
Thus, the marking 101B is detected in a non-contact state. The control unit 500 includes a marking detection unit 502
Angle measuring device 30 based on the detection of marking by
A circuit is configured to determine which number of the first to sixth mirror surfaces the mirror surface 101A to which 0 faces is the mirror surface. In this embodiment, the polygon mirror 101 having six mirrors will be described. However, the number of mirrors is not limited to this.

In this embodiment, only one set of angle adjusting means 400 is provided. As shown in the plan view of FIG. 5, the center axis of the motor shaft, the push pin 401 of the angle adjusting means 400, The light emitting unit 301 and the light receiving unit 302 of the tilt angle measuring device 300 are provided in such a positional relationship as to be on the same plane.

In the adjusting device of the present embodiment, the following adjustment is performed by the adjusting program of the light deflecting device included in the control section 500.

The control unit 500 rotates the motor MO to emit light toward the mirror surface 101A located directly opposite the light emitting unit 301 of the tilt angle measuring device 300, and transmits the reflected light to the light receiving unit 30.
The light is received by 2 and the tilt angle is measured for all 6 mirror surfaces. At that time, the marking detection unit 502 detects the marking 101B, and associates the mirror surface number with the tilt angle of the mirror surface. In FIG.
This is indicated by a mark. FIG. 5A shows an example of such a case, in which the control unit 500 has the mirror surface with the smallest tilt angle (No. 4) and the mirror surface with the largest tilt angle (No. 1) among the mirror surfaces.
Detecting the door to determine the amount of variation B _MAX of the maximum inclination angle. Then, the mirror surface (No. 1) having the largest tilt angle is rotated to the position facing the tilt angle measuring device 300, stopped, and the motor M2 of the angle adjusting means 400 is driven to push the push pin as a push member. No. 401 by No. 401. 1 is pushed down by a predetermined amount ΔH _{1 in the} direction in which the tilt angle of the mirror surface decreases.

The motor MO is rotated again to measure the mirror surface numbers and the inclination angles of the mirror surfaces for all six mirror surfaces. FIG. 5B shows an example of this, and the control unit 50
0 detects the mirror surface with the smallest inclination angle (No. 1) and the mirror surface with the largest inclination angle (No. 4) among the mirror surfaces, and obtains the maximum variation B _MAX ′ of the inclination angle. Then, the mirror surface (No. 4) having the largest tilt angle is rotated to a position facing the tilt angle measuring device 300, and stopped.
00 is driven by the push pin 401 and the motor M2 of No. 00 is driven. A predetermined amount ΔH ₂ (Δ
Press down by H ₂ <ΔH ₁ ).

The above operation is repeated until the maximum tilt angle variation B _MAX ^p becomes smaller than a preset limit value B _AL . After the adjustment is completed, the process waits until the adhesive filled in the gap S2 between the motor shaft 501 and the inner diameter of the polygon mirror 101 is completely fixed.

The adjusting device of the second embodiment described above performs the fine adjustment of the tilt angle fully automatically by the control unit 500, but is configured to realize this through a manual operation in the middle of this process. It may be.

[0031]

Heretofore, almost no adjustment or assembly for improving the tilt angle accuracy of the optical deflecting device has been introduced. The present invention provides an adjustment method and an adjustment device for performing adjustment so as to reduce variation in the tilt angle while measuring the tilt angle of the mirror surface of the polygon mirror. Along with the adjustment of the angle of inclination of the polygon mirror with respect to the cylinder, the angle of inclination of each mirror surface of the polygon mirror is also corrected, and the angle of inclination that was previously not obtained is corrected, and high-quality image recording is performed. A deflection device has been provided.

In the above adjustment, a slight gap is provided between the rotary shaft or the radial shaft outer cylinder and the polygon mirror, and when the adjustment is completed, it is fixed by the adhesive injected into the gap. As a result, assembly with low man-hours, which cannot be imagined in the past, can be performed with high accuracy.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an adjustment device of an optical deflection device according to a first embodiment.

FIG. 2 is a plan view of a polygon mirror part according to the first embodiment.

FIG. 3 is an explanatory diagram illustrating a process of adjusting a tilt angle according to the first embodiment.

FIG. 4 is a configuration diagram of an adjustment device for an optical deflection device according to a second embodiment.

FIG. 5 is a plan view of a polygon mirror part according to the second embodiment.

FIG. 6 is an explanatory diagram illustrating a process of adjusting a tilt angle according to the second embodiment.

FIG. 7 is a perspective view of a writing optical system to which an optical deflection device is attached.

FIG. 8 is a sectional configuration diagram of an optical deflection device having a dynamic pressure bearing.

[Explanation of symbols]

 Reference Signs List 101 polygon mirror 101A mirror surface 101B marking 102 radial axis outer cylinder 200, 500 control unit 300 tilt angle measuring device 301 light emitting unit 302 light receiving unit 400 angle adjusting means 401 push pin 501 motor shaft 502 marking detecting means MO, M1, M2 motor S1, S2 gap

Claims (5)

[Claims] 1. Prior to fixing a polygon mirror to a rotary shaft or a radial shaft outer cylinder, a tilt angle of each mirror surface of the polygon mirror with respect to the rotary shaft or the radial shaft outer cylinder is measured to reduce variation in the tilt angle. Adjusting the inclination of the polygon mirror in a direction in which the light is deflected. 2. The method according to claim 1, wherein the polygon mirror is fixed to the rotary shaft or the radial shaft outer cylinder at an adjustment position by using an adhesive. 3. A tilt angle measuring device comprising: a light source for irradiating a mirror surface of a polygon mirror; and a light receiving element for receiving light reflected from the mirror surface, the tilt angle measuring device measuring a tilt angle of the mirror surface, and an axial direction of the polygon mirror. And a tilt angle adjusting means of a polygon mirror comprising a pushing member which operates in a pushing direction in parallel with the tilt angle measuring means for measuring the tilt angle of each mirror surface by the tilt angle measuring device, and the tilt angle in a direction in which the variation of the tilt angle of the mirror surface decreases. An adjustment device for an optical deflecting device, comprising: a control unit that adjusts an adjustment unit; and adjusts a positional relationship of a polygon mirror extrapolated to a shaft portion or a radial shaft outer cylinder. 4. The adjustment of the optical deflecting device according to claim 3, further comprising a shaft fixing means for fixing the shaft or the radial shaft outer cylinder, and a rotating means for rotating the polygon mirror. apparatus. 5. The system according to claim 3, wherein the polygon mirror is in a semi-fixed state with the shaft portion or the radial shaft outer tube, and the shaft portion or the radial shaft outer tube is rotatable. An adjustment device for the optical deflection device according to claim 1.