JP2000089147A - Multi-beam scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust a line pitch on a rotary drum with high accuracy and at high speed, and also to promote miniaturization of the device. SOLUTION: Two laser beams P1, P2 generated from multi-beam semiconductor laser 11 is made to scan by a polygon mirror in an optical box 8, and forms an image on a photoreceptor on the rotary drum via an image-forming lens. To adjust a line pitch T on the photoreceptor, when the multi-beam semiconductor laser 11 is assembled on a laser holder 11a, the multi-beam semiconductor laser 11 is fixed on the laser holder 11a in a turned state so that the laser array N has a predetermined inclination θ. When assembling the multi-beam light source unit 1 in the optical box 8, the whole multi-beam light source unit has only to be slightly inclined to supplement the part accuracy, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-beam scanning device used for a laser beam printer, a digital copying machine, and the like.

[0002]

2. Description of the Related Art In recent years, in an electrophotographic apparatus such as a laser beam printer, a multi-beam scanning apparatus for simultaneously writing a plurality of lines using a plurality of laser beams has been developed.

In this method, a plurality of laser beams separated from each other are scanned at the same time. As shown in FIG. 9, a multi-beam semiconductor laser 111 serving as a light source of a multi-beam light source unit 101 emits two laser beams. Beams P ₁ and P ₂ are generated, and collimator lens 1
After being collimated by 12, the light is irradiated on the reflection surface 103 a of the rotating polygon mirror 103 through the cylindrical lens 102, and is imaged on the photosensitive member on the rotating drum 105 via the imaging lens 104.

The two laser beams P ₁ and P ₂ are incident on the reflection surface 103 a of the rotary polygon mirror 103, are scanned in the main scanning direction, and are scanned by the rotation of the rotary polygon mirror 103 and the rotation of the rotary drum 105. An electrostatic latent image is formed on the photoconductor with the sub-scan.

The cylindrical lens 102 transmits the laser beams P ₁ and P ₂ to the reflecting surface 1 of the rotating polygon mirror 103.
The light is condensed linearly on 03a. This has a function of preventing the point image formed on the photoconductor from being distorted due to the tilting of the rotary polygon mirror 103 as described above, and the imaging lens 104 has a spherical lens unit. It has a function of preventing the distortion of a point image on the photoconductor similarly to the cylindrical lens 102, and has a function of correcting the point image to be scanned at a constant speed in the main scanning direction on the photoconductor. Having.

[0006] The two laser beams P ₁ and P ₂ are separated by a detection mirror 106 at the end of the main scanning plane (XY plane), respectively, and introduced into an optical sensor 107 on the opposite side of the main scanning plane, not shown. The signal is converted into a write start signal by the controller and transmitted to the multi-beam semiconductor laser 111. Upon receiving the write start signal, the multi-beam semiconductor laser 111 starts write modulation of both laser beams P ₁ and P ₂ .

By adjusting the timing of the write modulation of the two laser beams P ₁ and P _{2 in} this manner, the write start (write) position of the electrostatic latent image formed on the photoconductor on the rotating drum 105 is controlled. .

[0008] The cylindrical lens 102, the rotating polygon mirror 103, the imaging lens 104 and the like are mounted on the bottom wall of the optical box 108. After assembling the optical components into the optical box 108, the upper opening of the optical box 108 is closed by a lid member (not shown).

The multi-beam semiconductor laser 111 emits a plurality of laser beams P ₁ and P ₂ at the same time as described above, and is integrally connected to a lens barrel 112a containing a collimator lens 112 via a laser holder 111a. Of the optical box 108 together with the laser drive circuit board 113.

When assembling the multi-beam light source unit 101, the laser holder 111a holding the multi-beam semiconductor laser 111 is attached to the side wall 108 of the optical box 108.
a into the opening 108b provided in the laser holder 1
The lens barrel 112a of the collimator lens 112 is placed over the lens holder 11a, the focus of the collimator lens 112 is adjusted and the optical axis is adjusted.
10A, and by rotating the laser holder 111a by a predetermined angle θ as shown in FIG. 10A, a straight line connecting the light emitting points of the laser beams P ₁ and P ₂ , that is, the inclination of the laser array N is increased. Adjust the angle. This is shown in FIG.
(B), the multi-beam semiconductor laser 11
By adjusting the beam interval between the _two laser beams P ₁ and P ₂ generated from the laser beam P ₁ , the imaging points A ₁ and P ₂ on the rotating drum 105 are adjusted.
The distance or line interval T of the distance S and the sub-scanning direction of the main scanning direction A ₂ is an adjustment task to match the design value. After performing this operation, the laser holder 111a is fixed to the side wall 108a of the optical box 108 using screws or the like.

[0011]

However, according to the above-mentioned prior art, when the multi-beam light source unit is fixed to the optical box, the entire multi-beam light source unit is rotated together with the laser drive circuit board by a predetermined angle .theta. In order to obtain the interval T, it is necessary to provide a sufficient space for rotating the laser drive circuit board having a large area outside the optical box, which is an obstacle to downsizing the entire apparatus. Has become.

The adjustment of the line interval T is extremely strict with an allowable value of an error of several μm or less. Therefore, if the range of angle adjustment when assembling the multi-beam light source unit to the optical box is wide, high accuracy can be achieved. There is also an unsolved problem that it is difficult to complete the adjustment in a short time, and it is not possible to perform an assembly that satisfies work efficiency and reliability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned unresolved problems of the prior art, and is intended to promote miniaturization of an apparatus and to adjust a beam interval with high accuracy in a short time. It is an object of the present invention to provide a multi-beam scanning device that can perform the scanning.

[0014]

In order to achieve the above object, a multi-beam scanning apparatus according to the present invention comprises a multi-beam semiconductor laser, a multi-beam light source unit having a laser holder for holding the multi-beam semiconductor laser, and a multi-beam semiconductor laser. A scanning imaging unit configured to scan a plurality of laser beams generated from a laser to form an image on a photoconductor, and a housing that supports the scanning imaging unit and the multi-beam light source unit; A laser is fixed to the laser holder at a predetermined rotation angle for adjusting a beam interval between the plurality of laser beams or a rotation angle close thereto.

It is preferable that the multi-beam semiconductor laser has a plurality of light emitting points arranged linearly.

[0016] The multi-beam semiconductor laser may have a plurality of light emitting points arranged two-dimensionally.

Preferably, the laser holder is integral with the lens barrel holding the collimator lens.

[0018]

[Function] When assembling the laser holder to the housing after fixing the multi-beam semiconductor laser to the laser holder,
If the configuration is such that the entire multi-beam light source unit is tilted (rotated) to adjust the beam interval, precise angle adjustment is difficult, and the adjustment work takes time.
An extra space for inclining the large-area laser drive circuit board assembled in the multi-beam light source unit is also required. Therefore, in the unit assembling process of assembling the multi-beam semiconductor laser to the laser holder, the multi-beam semiconductor laser is rotated (tilted) to an angle necessary for adjusting the beam interval or an angle close to the angle, and the multi-beam semiconductor laser is mounted in this state. Unitized by fixing to laser holder.

When assembling the multi-beam light source unit to the housing, the entire multi-beam light source unit may be rotated by a small angle in order to finally adjust a slight error caused by component accuracy or the like.

As described above, since the final angle adjustment work when assembling the multi-beam light source unit to the housing is performed in a minute angle range, the angle can be adjusted with high accuracy and quickly.

Further, since there is no need to tilt the laser drive circuit board having a large area greatly, it is possible to contribute to downsizing of the entire apparatus.

[0022]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a multi-beam scanning device according to an embodiment, which is composed of multi-beam semiconductor lasers 11 to 2 which are light sources of a multi-beam light source unit 1.
Laser beams P ₁ and P ₂ , which are book light beams, are generated, collimated by a collimator lens 12, and then passed through a cylindrical lens 2 to a rotating polygon mirror 3.
Of the photosensitive drum on the rotating drum 5 via an imaging lens 4 constituting a scanning imaging means together with the rotary polygon mirror 3.

The two laser beams P ₁ and P ₂ are incident on the reflection surface 3a of the rotary polygon mirror 3 and are respectively scanned in the main scanning direction.
The electrostatic latent image is formed on the photosensitive member with the sub-scanning due to the rotation of.

The cylindrical lens 2 condenses the laser beams P ₁ and P ₂ linearly on the reflecting surface 3 a of the rotary polygon mirror 3. This has the function of preventing the point image formed on the photoreceptor from being distorted due to the tilting of the rotary polygon mirror 3 as described above, and the imaging lens 4 is provided with a spherical lens unit. A function of preventing a distortion of a point image on the photoconductor, similarly to the cylindrical lens 2, and a function of correcting the point image to be scanned at a constant speed in the main scanning direction on the photoconductor. Having.

The two laser beams P ₁ and P ₂ are separated by the detection mirror 6 at the end of the main scanning plane (XY plane), respectively, and introduced into the optical sensor 7 on the opposite side of the main scanning plane, not shown. The signal is converted into a write start signal by the controller and transmitted to the multi-beam semiconductor laser 11. Upon receiving the write start signal, the multi-beam semiconductor laser 11 starts write modulation of both laser beams P ₁ and P ₂ .

By adjusting the timing of the write modulation of the two laser beams P ₁ and P _{2 in} this manner, the write start (write) position of the electrostatic latent image formed on the photoconductor on the rotating drum 5 is controlled. .

A cylindrical lens 2, a rotary polygon mirror 3,
The imaging lens 4 and the like are mounted on the bottom wall of the optical box 8 as a housing. After assembling each optical component into the optical box 8,
The upper opening of the optical box 8 is closed by a lid member (not shown).

The multi-beam semiconductor laser 11 emits a plurality of laser beams P ₁ and P ₂ at the same time as described above, and is integrally connected to a lens barrel 12a containing a collimator lens 12 via a laser holder 11a. Of the optical box 8 together with the laser drive circuit board 13.

When assembling the multi-beam light source unit 1, the laser holder 11a holding the multi-beam semiconductor laser 11 is inserted into an opening 8b provided in the side wall 8a of the optical box 8, and the mirror of the collimator lens 12 is mounted on the laser holder 11a. After three-dimensional adjustment such as focus adjustment and optical axis alignment of the collimator lens 12 is performed by covering the cylinder 12a, the lens barrel 12a is bonded to the laser holder 11a.

As shown in FIG. 2, the multi-beam semiconductor laser 11 includes a laser chip 22 fixed to a pedestal 21a integral with a stem 21, and a laser beam emitted from two light emitting points 22a and 22b of the laser chip 22. Beam P
_1, a photodiode 23 for monitoring the light emission amount of P ₂
And an energizing terminal 24 for energizing the laser chip 22 and the like.
, And the laser chip 22 and the like are covered by the cap 25.

The multi-beam semiconductor laser 11 is a unit assembling step for assembling the same into the laser holder 11a.
As shown in FIG. 3, by rotating the multi-beam semiconductor laser 11 to a predetermined rotation angle θ or an angle close to the predetermined rotation angle θ with respect to the reference plane V of the laser holder 11a, each of the laser beams P ₁ and P ₂ The straight line connecting the light emitting points, that is, the inclination angle of the laser array N is adjusted in advance. This corresponds to the 2 generated from the multi-beam semiconductor laser 11.
The distance between the _two laser beams P ₁ and P ₂ is adjusted, and the distance S between the image forming points A ₁ and A ₂ on the rotating drum 5 in the main scanning direction and the distance between the imaging points A ₁ and A _{2 in} the sub scanning direction, that is, the line distance T are designed in advance. This is an adjustment operation for matching the values (see FIG. 3B). After the adjustment work, the multi-beam semiconductor laser 11 is fixed to the laser holder 11a and unitized.

After the lens barrel 12a of the collimator lens 12 is bonded to the laser holder 11a as described above, as shown in FIG.
1b, the laser holder 11a is moved to the side wall 8a of the optical box 8.
To the laser holder 11 for final adjustment of the line interval T while emitting the laser beams P ₁ and P _2.
a is rotated by a small angle Δθ. This work is for compensating for the component accuracy of each part of the apparatus and the error of the fitting part of the multi-beam semiconductor laser 11 itself. In practice, as shown by a broken line in FIG. Is carried out in a state where it is assembled. After such final adjustment, the laser holder 11a is fixed to the optical box 8 by tightening the screw 11b.

Although the adjustment of the line interval T on the rotating drum requires accuracy on the order of submicron, in the present embodiment, when the multi-beam semiconductor laser is assembled to the laser holder, the laser array N is set in advance. In the process of assembling the laser holder to the optical box together with the laser drive circuit board, the final adjustment of the minute angle is only necessary to correct the assembly error etc. It is. Therefore, the accuracy in the final adjustment of the line interval is extremely high, and the time required for the adjustment operation can be greatly reduced as compared with the case where the angle is adjusted over a wide range on the optical box as in the conventional example. In addition, since it is not necessary to rotate the laser drive circuit board having a large area outside the optical box, it is possible to greatly reduce the size of the apparatus.

As a result, it is possible to realize a multi-beam scanning apparatus which is small, has low assembly cost, and has extremely high accuracy.

Although a laser chip having two light emitting points is used in this embodiment, any number of light emitting points, that is, the number of laser beams may be used. The procedure for assembling the laser drive circuit board, the lens barrel, the collimator lens, and the like can be freely changed. Further, the fixing of the laser holder to the optical box is not limited to fastening means such as screws, but may be other methods such as bonding.

FIG. 6 shows a modification. This is the reference plane V
A disk-shaped laser holder 31a is used in place of the substantially rectangular laser holder 11a whose end face is.
In this case, the reference plane U of the rotation angle θ when assembling the multi-beam semiconductor laser 31 to the laser holder 31a is used.
To the notch 3 provided on the outer peripheral portion of the laser holder 31a.
1b.

As shown in FIG. 7, the laser driving circuit board 3
3 is assembled to the laser holder 31a such that the upper end surface 33a becomes a reference for attachment to an optical box (not shown).

As shown in FIG. 8, a plurality of light emitting points 42a to 42d are used instead of the edge emitting multi-beam semiconductor lasers 11, 31 in which a plurality of light emitting points are linearly arranged.
May be used. A multi-beam semiconductor laser 41 having a surface-emitting type laser chip 42 in which are two-dimensionally arranged may be used.
This has a remarkable advantage that optical aberrations can be reduced because all light emitting points can be brought close to the optical axis of the collimator lens. A positioning hole 41b is provided in the disc-shaped laser holder 41a, and the beam interval T
_It is used as a positioning reference when adjusting the rotation angle θ for adjusting _{1 to} T ₃ .

The use of a surface emitting laser also has the advantage that the degree of freedom of the position of the light emitting point and the like is increased, and the distribution of assembly tolerances is facilitated.

[0041]

Since the present invention is configured as described above, the following effects can be obtained.

The operation of adjusting the beam interval between a plurality of laser beams emitted from the multi-beam semiconductor laser can be performed in a short time and with high accuracy. As a result, high definition of the device can be promoted, assembling cost can be significantly reduced, and further, it is possible to greatly contribute to downsizing of the entire device.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a multi-beam scanning device according to an embodiment.

FIG. 2 is an enlarged perspective view showing the multi-beam semiconductor laser of the apparatus of FIG. 1 in an enlarged manner.

FIG. 3 is a diagram illustrating an operation of adjusting a line interval.

FIG. 4 is a perspective view showing a state where the laser holder is temporarily fixed to the optical box.

FIG. 5 is a diagram illustrating a final adjustment operation of a line interval.

FIG. 6 is a schematic diagram showing a modification.

FIG. 7 is a schematic diagram showing the device of FIG. 6 together with a laser drive circuit board.

FIG. 8 is a schematic diagram showing another modification.

FIG. 9 is a schematic plan view showing a conventional multi-beam scanning device.

FIG. 10 is a diagram illustrating an operation of adjusting a line interval in the multi-beam scanning device of FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multi-beam light source unit 2 Cylindrical lens 3 Rotating polygon mirror 4 Imaging lens 8 Optical box 11, 31, 41 Multi-beam semiconductor laser 11a, 31a, 41a Laser holder 11b Screw 12 Collimator lens 12a Lens barrel 13, 33 Laser drive circuit board

Claims (4)

[Claims] 1. A multi-beam light source unit including a multi-beam semiconductor laser and a laser holder for holding the multi-beam semiconductor laser, and a plurality of laser beams generated from the multi-beam semiconductor laser are scanned to form an image on a photosensitive member. An imaging unit, having a housing that supports the scanning imaging unit and the multi-beam light source unit, wherein the multi-beam semiconductor laser has a predetermined rotation angle or a predetermined rotation angle for adjusting a beam interval between the plurality of laser beams. A multi-beam scanning device, wherein the multi-beam scanning device is fixed to the laser holder at a rotation angle close to this. 2. The multi-beam scanning device according to claim 1, wherein the multi-beam semiconductor laser has a plurality of light-emitting points arranged in a straight line. 3. The multi-beam scanning device according to claim 1, wherein the multi-beam semiconductor laser has a plurality of light emitting points arranged two-dimensionally. 4. The multi-beam scanning device according to claim 1, wherein the laser holder is integrated with a lens barrel holding the collimator lens.