JPH11142754A - Laser orientation adjusting method of image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and accurately enable the orientation adjustment by making the Y coordinate component of the optical axis of a collimator lens zero by rotating a rotary holder rotating about an axis being eccentric to the optical axis of the collimator lens and compensating the deviation between the X coordinate component of the optical axis of the collimator lens and the origin. SOLUTION: A semiconductor laser 14 and a collimator lens 16 are fixed to a through-hole 30 and a lens barrel 34, respectively, the lens barrel 34 is inserted into a through-hole 32 of a holder 28. Until the semiconductor laser 14 is activated and a laser beam is transmitted in Z direction (horizontal direction), the lens barrel is rotated about the rotary axis 36. Namely, when the laser beam passed through the collimator lens 16 is transmitted in the Z direction, the optical axis 40 of the collimator lens 16 is in coincident with the Y coordinate component of the optical axis 42 of the semiconductor laser 14 with each other. When the alignment of optical axis in the Y axial direction is completed, the lens barrel 34 is fixed to the holder 28. The deviation of optical axis in X direction is compensated by a photodetector in the period of image forming operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting laser directivity of an image forming apparatus, and more particularly to a laser printer and a digital copying machine which form an image by scanning a photosensitive member with a laser beam corresponding to image data. The present invention also relates to a laser pointing adjustment method for an image forming apparatus that forms a desired beam spot on a photoconductor by making the optical axis of a laser light source (laser light output means) coincide with the optical axis of a collimator lens.

[0002]

2. Description of the Related Art An example of this kind of conventional technology is disclosed in
It is disclosed in Japanese Patent Application Laid-Open No. 5-225575 [G11B 7/08], which was published on March 3, 2003. This conventional technique supports a rotator having a rotation axis decentered with respect to the optical axis of a collimator lens so as to be movable in a direction orthogonal to the optical axis of the collimator lens, and a horizontal direction orthogonal to the optical axis of the semiconductor laser element. The rotating body (lens holding tube) is rotated until the optical axis of the collimator lens is positioned inside the lens, and the lens holding tube is moved in a direction perpendicular to the optical axis of the collimator lens so that the optical axis of the collimator lens and the semiconductor laser This is to match the optical axis of the element.

[0003]

In the prior art, a semiconductor laser device and a collimator lens (lens holding cylinder) are used.
Is required to be manually displaced in the XY axis direction with the optical axis of the semiconductor laser element as the origin. Therefore, unless a skilled person, the XY coordinate components are satisfied at the same time, and a highly accurate optical axis is obtained. It is difficult to perform matching (directivity adjustment).

Further, according to the above-mentioned prior art, the optical axis can be easily aligned in the Y-axis direction by rotating the lens holding tube. However, when the processing accuracy of the lens holding tube and the support frame is extremely poor, However, since the optical axis is aligned in the X-axis direction, there is also a problem that when the lens holding cylinder is displaced along the movement groove, the adjusted Y coordinate is shifted.

[0005] Therefore, a main object of the present invention is to align the optical axis (directivity adjustment) of the collimator lens and the laser light source.
To provide a laser pointing adjustment method for an image forming apparatus, which can easily and accurately perform the above.

[0006]

SUMMARY OF THE INVENTION The present invention provides a laser light output means for outputting a laser light, a collimator lens for deflecting the laser light into parallel light, a rotation holding the collimator lens and eccentric to the optical axis of the collimator lens. A rotation holding member that rotates around an axis, a photoconductor that scans a laser beam to form an electrostatic latent image on a surface, and a scanning start position control that is provided in association with the photoconductor and controls a scanning start position of the laser beam A laser direction adjusting method for an image forming apparatus, comprising: an XY coordinate system having an optical axis of a laser light output unit as an origin; A laser pointing adjustment method for an image forming apparatus, wherein a component is set to zero and a deviation between an X coordinate component of an optical axis of a collimator lens and an origin is corrected by a scanning start position control unit.

[0007]

The collimator lens is held by a rotation holder which rotates around a rotation axis decentered from the optical axis. When the rotation is applied to the rotation holder, the optical axis of the collimator lens is displaced along a locus of a perfect circle when viewed from the rotation axis direction of the rotation holder. Therefore, by applying rotation to the rotation holder and directing the laser light passing through the collimator lens in the horizontal direction, the Y coordinate components of the optical axis of the laser light output unit and the optical axis of the collimator lens can be made to coincide with each other. it can.

At this time, there is a deviation between the X-axis component of the optical axis of the collimator lens and the optical axis of the laser light output means. This deviation can be corrected by the scanning start position control means during the image forming operation. That is, the deviation of the X coordinate components of both optical axes occurs as a deviation in the main scanning direction of the laser light, that is, a deviation of the scanning start position (writing position) of the laser light, and controls the scanning start position of the laser light. Can be corrected by the scanning start position control means.

[0009]

According to the present invention, the deviation of the X coordinate component between the optical axis of the laser light output means and the optical axis of the collimator lens can be calculated.
Since the correction is performed by controlling the scanning start position during the image forming operation period, the optical axis alignment need only be made to manually match only the Y coordinate components of both optical axes. Therefore, the optical axis alignment can be performed easily and accurately ( Pointing adjustment).

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A light source device 10 of this embodiment shown in FIG. 1 is a laser printer, a digital copying machine, or the like that forms an image by scanning a laser beam output in accordance with image data on a photosensitive member 24 described later. This is applied to the image forming apparatus 12 (see FIG. 2). That is, the image forming apparatus 12 shown in FIG.
Includes a light source device 10 to be described later.
Are collimated (collimated) with a semiconductor laser 14 as a laser light output unit and a radiant light beam from the semiconductor laser 14.
and e) a collimator lens 16. Image data transmitted from an image reading device such as an image scanner (not shown) is provided to the semiconductor laser 14, and a laser beam is output from the semiconductor laser 14 accordingly. After being deflected by the collimator lens 16 into parallel light, the laser light is guided via the cylindrical lens 18 to the deflector 20 composed of a polygon mirror or the like. The deflector 20 has a plurality of reflecting surfaces 20a, and imparts rotation to the deflector 20 in a direction indicated by an arrow A to displace each of the reflecting surfaces 20a. Light main scanning is performed. Then, the deflected laser light is condensed by the fθ lens 22, and then is incident on the photoconductor 24 to form an electrostatic latent image on the photoconductor 24.

The laser beam is repeatedly scanned by the deflector 20 on the photosensitive member 24 in the direction of arrow B.
If there is a variation in the division angle of 0a, the exposure width differs for each scan, that is, a variation occurs in the scanning start position (write start position). A photodetector 26 such as a diode is provided to control the scanning start position of the laser beam. That is, the laser light for the scanning start position signal reflected by the deflector 20 is detected by the photodetector 26 provided in association with the photoconductor 24, and the obtained start position signal and the reference clock signal are synchronized. By letting
The scanning start position (write start position) on the photoconductor 24 is controlled. That is, the photodetector 26 constitutes a scanning start position control unit.

Returning to FIG. 1, the light source device 10 includes a holder 2
1 and the right side of FIG. 1 (Z-axis direction)
From the viewpoint, substantially circular through holes 30 and 32 are formed. The semiconductor laser (laser light output means) 14 is engaged with the through-hole 30, and the cylindrical lens barrel (rotation holder) 34 is engaged with the through-hole 32. More specifically, the diameter of the through-hole 30 is made substantially equal to the outer diameter of the semiconductor laser 14, and the semiconductor laser 14 is fixed to the through-hole 32 by press-fitting and bonding, and the semiconductor laser 14 is positioned. On the other hand, the diameter of the through hole 32 is set slightly larger than the outer diameter of the lens barrel 34.
The lens barrel 34 is rotatably held around the rotation shaft 36 in a state of being inserted (engaged) into the lens barrel 2.

The collimator lens 16 is fixedly provided in the through hole 38 of the lens barrel 34. 1, the optical axis 40 of the collimator lens 16 and the rotation axis 36 of the lens barrel 34 are decentered, and the collimator lens 16 is mounted inside the lens barrel 34. As described above, since the lens barrel (rotation holding member) 34 is held rotatably about the rotation axis 36 with respect to the holding member 28,
By applying rotation to the lens barrel 34, the optical axis 40 of the collimator lens 16 is displaced along a locus of a true circle centered on the rotation axis 36 when viewed from the Z-axis direction in FIG. Therefore, by rotating the lens barrel 34 around the rotation axis 36 in the XY coordinate system whose origin is the optical axis (light emitting point) of the semiconductor laser 14, the optical axis 4 of the collimator lens 16 is
The X coordinate component and the Y coordinate component of 0 can be respectively displaced.

Next, a method of aligning the optical axis of the semiconductor laser 14 and the collimator lens 16, that is, a method of adjusting the directivity of the laser light will be described. First, the semiconductor laser 14 is fixed to the through hole 30, and the collimator lens 16 is fixed to the lens barrel 34 by press-fitting and bonding, and then the lens barrel 34 is inserted into the through hole 32 of the holder 28. Then, the semiconductor laser 14 is activated, and the lens barrel 34 is rotated around the rotation axis 36 until the laser light is emitted in the Z-axis direction (horizontal direction). That is, when the laser light that has passed through the collimator lens 16 is emitted in the Z-axis direction (horizontal direction), the Y-axis components of the optical axis 40 of the collimator lens 16 and the optical axis 42 of the semiconductor laser 14 match each other. When the optical axis alignment in the Y-axis direction is completed in this way, the lens barrel 34 is fixed to the holder 28 with an adhesive or the like. In this state, although the optical axis alignment in the X-axis direction has not been performed, the deviation of the optical axis in the X-axis direction can be corrected during the image forming operation period.

That is, the shift of the optical axis in the X-axis direction does not adversely affect the optical performance, and occurs as a shift of the scan start position (write start position) of the image data. Therefore, the difference between the X-axis component of the optical axis 40 of the collimator lens 16 and the X-coordinate component of the optical axis 42 of the semiconductor laser 14 is determined by detecting the laser beam reflected by the deflector 20 by the photodetector 26 and detecting the start position signal. The correction is made in the process of controlling the scanning start position on the photosensitive member 24 based on the above. Therefore, XY with the optical axis 42 (light emitting point) of the semiconductor laser 14 as the origin.
In the coordinate system, the optical axis alignment (directivity adjustment) between the collimator lens 16 and the semiconductor laser 14 that is manually performed may be performed only by adjusting the optical axis in the Y-axis direction by rotating the lens barrel 34.

In this embodiment, the collimator lens 16 is held rotatably about a rotation axis 36 eccentric to the optical axis 40, and rotation is given to the collimator lens 16 (barrel 34). The Y-coordinate component of the optical axis 42 and the Y-coordinate component of the optical axis 40 of the collimator lens 16 are made coincident with each other, and the shifted X-coordinate component is corrected by scanning start position control during the image forming operation period. In addition, the optical axis alignment (laser pointing adjustment) can be performed with high accuracy.

[Brief description of the drawings]

FIG. 1 is an illustrative view showing one embodiment of the present invention;

FIG. 2 is a configuration diagram illustrating an image forming apparatus to which the light source device of FIG. 1 is mounted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Light source device 12 ... Image forming apparatus 14 ... Semiconductor laser 16 ... Collimator lens 24 ... Photoconductor 26 ... Photodetector 28 ... Holder 34 ... Barrel 36, 40, 42 ... Optical axis

Claims (1)

[Claims] 1. A laser light output means for outputting laser light, a collimator lens for deflecting the laser light into parallel light, and holding the collimator lens and rotating about a rotation axis decentered from the optical axis of the collimator lens. A rotation holding member, a photosensitive member that scans the laser light to form an electrostatic latent image on a surface, and a scanning start position control unit that is provided in association with the photosensitive member and controls a scanning start position of the laser light. A laser pointing adjustment method for an image forming apparatus, comprising: an XY coordinate system having an optical axis of the laser light output unit as an origin; A laser of the image forming apparatus, wherein the coordinate component is set to zero, and a deviation between the X coordinate component of the optical axis of the collimator lens and the origin is corrected by the scanning start position control means. Direction adjustment method.