JP2000162536A - Light beam scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an accurately adjusted line interval from being changed. SOLUTION: A laser holder 11a holding a multibeam semiconductor laser 11 emitting plural laser beams P1 and P2 is freely rotatably supported in an engagement hole formed at the side wall 8a of an optical box 8 and clamped to the box 8 by a machine screw 8c after the angle thereof is adjusted to the prescribed rotating angle for adjusting the line interval. In order to prevent the holder 11a from being rotated by disturbance such as impact after it is assembled, the tip of a fixing screw 8e is engaged with the groove part 11b of the holder 11a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, in an electrophotographic apparatus such as a laser beam printer, a light 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 simultaneously scanned. As shown in FIG. 7, two laser beams from a multi-beam semiconductor laser 111 (see FIG. 8) as a light source of a multi-beam light source unit 101 are used. After a laser beam is generated and collimated by a collimator lens 112, the laser beam is radiated to a reflecting surface of a rotary polygon mirror 103 via a cylindrical lens 102, thereby forming an image forming lens 1
The image is formed on the photoreceptor on the rotating drum through the mirror 04 and the return mirror 105.

The two laser beams are incident on the reflecting surface of the rotary polygon mirror 103 and are respectively scanned in the main scanning direction. The two laser beams are exposed along with the main scanning by the rotation of the rotary polygon mirror 103 and the sub-scan by the rotation of the rotary drum. Form an electrostatic latent image on the body.

[0005] The cylindrical lens 102 condenses each laser beam linearly on the reflection surface of the rotary polygon mirror 103. This is because the point image formed on the photoreceptor
It has a function of preventing distortion from occurring due to the tilting of the rotating polygon mirror 103, and the imaging lens 104 is composed of a spherical lens unit and a toric lens unit, and is formed on the photosensitive member similarly to the cylindrical lens 102. It has a function of preventing distortion of the point image and a function of correcting the point image so that the point image is scanned at a constant speed in the main scanning direction on the photoconductor.

The two laser beams 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.
The data is converted into a write start signal by a controller (not shown) and transmitted to the multi-beam semiconductor laser 111. Upon receiving the write start signal, the multi-beam semiconductor laser 111 starts writing modulation of each laser beam.

[0007] By adjusting the timing of the write modulation of both laser beams in this way, the write start (write) position of the electrostatic latent image formed on the photosensitive member on the rotating drum 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).

As shown in FIG. 8, the multi-beam semiconductor laser 111 emits a plurality of laser beams simultaneously as described above, and is integrated with a lens barrel 112a having a collimator lens 112 via a laser holder 111a. Is mounted on the side wall 108a of the optical box 108 together with the laser drive circuit board.

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 a fitting hole 108b provided in the collimator lens 112a, cover the laser holder 111a with the lens barrel 112a of the collimator lens 112, perform three-dimensional adjustment such as focus adjustment and optical axis alignment of the collimator lens 112, and then perform mirror adjustment. The cylinder 112a is bonded to the laser holder 111a. Subsequently, as shown in FIG. 9A, the laser holder 111a is
The rotation within 08b adjusts the straight line connecting the light emitting points B ₁ and B ₂ of each laser beam, that is, the tilt angle θ of the laser array N. This is because, as shown in (b) of FIG.
This is an adjustment operation of adjusting the beam interval between the two laser beams, that is, adjusting the pitch S in the main scanning direction and the pitch T in the sub-scanning direction of the imaging points A ₁ and A ₂ on the rotating drum to the designed 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 prior art, as described above, the multi-beam light source unit is rotated and adjusted, and then fixed to the side wall of the optical box using screws or the like. Due to insufficient fixing with screws etc., the multibeam light source unit is rotated by disturbance such as impact after the above adjustment, and the position of the light emitting point and the line interval, that is, the pitch in the sub scanning direction fluctuates. Issues.

In the adjustment of the line interval, the allowable value of the error is several μm.
m or less, the image performance of the light beam scanning device is significantly deteriorated even if the adjustment position of the rotation angle of the multi-beam light source unit is slightly shifted due to impact or the like.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned unresolved problems of the prior art, and has a high-performance light beam in which a line interval or the like adjusted with high accuracy is not likely to be changed by disturbance such as an impact. It is an object to provide a scanning device.

[0014]

In order to achieve the above object, a light 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. Scanning imaging means for scanning each of a plurality of laser beams generated from a laser to form an image on a photoreceptor; a housing having a fitting portion rotatably supporting the multi-beam light source unit; The multi-beam light source unit includes a rotation preventing unit configured to prevent a rotation shift after adjusting a rotation angle of the light source unit, and a fastening unit configured to fasten the multi-beam light source unit to the housing.

The adjusting means for adjusting the rotation angle of the multi-beam light source unit with respect to the fitting portion of the housing may also serve as the rotation preventing means.

[0016]

The multi-beam light source unit is rotated in a state where the multi-beam light source unit is fitted into the fitting hole of the optical box as a housing, and the line spacing of a plurality of laser beams is adjusted. The multi-beam light source unit is fastened to the optical box by fastening means such as screws and screws.

Since the multi-beam light source unit may rotate when external disturbance such as an impact is applied only by fastening with screws or the like, a rotation preventing means for preventing a rotational deviation from the adjustment position is provided. By providing the fastening means and the rotation preventing means together, it is possible to realize a highly reliable light beam scanning apparatus which does not have a possibility that a line interval or the like which is adjusted with high accuracy is deviated.

[0018]

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

FIG. 1 shows a light beam scanning device according to a first embodiment, which is a multi-beam semiconductor laser 11 (FIG.
Laser beams P ₁ , P
₂ are collimated by a collimator lens 12, and then irradiate a reflecting surface 3 a of a rotary polygon mirror 3 via a cylindrical lens 2 to form an imaging lens 4 which forms a scanning image forming means together with the rotary polygon mirror 3. Then, an image is formed on a photoreceptor on a rotating drum (not shown) via the folding mirror 5.

The two laser beams P ₁ and P ₂ are incident on the reflecting surface 3a of the rotary polygon mirror 3 and are respectively scanned in the main scanning direction. The main scanning by the rotation of the rotary polygon mirror 3 and the sub-scanning by the rotation of the rotary drum. An electrostatic latent image is formed on the photoconductor with the scanning.

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. It comprises a toric lens section and the like, has a function of preventing the distortion of a point image on the photoconductor similarly to the cylindrical lens 2, and corrects the point image so that the point image is scanned on the photoconductor in the main scanning direction at a constant speed. Has functions.

The two laser beams P ₁ and P ₂ are separated by a detection mirror 6 at the end of the main scanning plane (XY plane), respectively, and introduced into an 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 each of the laser beams P ₁ and P ₂ .

By adjusting the timing of the write modulation of the laser beams P ₁ and P _{2 in} this way, the write start (write) position of the electrostatic latent image formed on the photoconductor on the rotating drum 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 simultaneously as described above, and as shown in FIG. 3, a mirror having a collimator lens 12 built in via a laser holder 11a. As a unit integrally connected to the cylinder 12a, the unit is mounted on the side wall 8a of the optical box 8 together with the laser drive circuit board.

When assembling the multi-beam light source unit 1, the laser holder 11a holding the multi-beam semiconductor laser 11 is fitted into a fitting hole 8b, which is a fitting portion provided on the side wall 8a of the optical box 8, and rotated. Freely supported,
The lens barrel 12 of the collimator lens 12 is mounted on the laser holder 11a.
a to adjust the focus of the collimator lens 12 and the three-dimensional adjustment such as the optical axis alignment.
Is adhered 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 21 a integral with a stem 21, and laser beams P ₁ and P ₂ emitted from two emission points of the laser chip 22. 2 for monitoring the amount of light emitted from
3 and an energizing terminal 2 for energizing the laser chip 22 and the like.
4 and the laser chip 22 and the like are covered with a cap 25. The output of the photodiode 23 is used for an APC operation for keeping the light emission amount of the laser chip 22 constant.

The laser holder 11a for holding the multi-beam semiconductor laser 11 is fitted to the side wall 8a of the optical box 8 in the step of assembling as shown in FIG. By rotating in the hole 8b, a straight line connecting the light emitting points of the laser beams P ₁ and P ₂ , that is, the inclination angle θ of the laser array N is adjusted. This is because the beam spacing between the _two laser beams P ₁ and P ₂ generated from the multi-beam semiconductor laser 11 is adjusted, that is, the pitch S in the main scanning direction of the imaging points A ₁ and A ₂ on the rotating drum and the sub-scanning This is an adjustment operation in which the pitch in the direction, that is, the line interval T is made to match a design value in advance (see FIG. 4C).

The operation of rotating the multi-beam light source unit 1 for adjusting the line interval is performed in the following procedure. First, the laser holder 1 is placed on the side wall 8a of the optical box 8.
The laser holder 11a is temporarily fixed by a screw 8c which is a fastening means fitted into the long hole of the laser holder 11a. At this time, a ring-shaped spacer 8d for penetrating the screw 8c may be interposed between the laser holder 11a and the side wall 8a of the optical box 8 (FIG. 3).
reference).

The laser holder 11a is rotated, and the rotation angle is adjusted so that the laser array N has a predetermined inclination angle θ.

After such adjustment work, the screw 8c is tightened to fasten the laser holder 11a to the side wall 8a of the optical box 8.

As described above, the multi-beam light source unit 1 after the rotation is adjusted is screwed to the side wall 8a of the optical box 8, but the screw 8c alone is used when the external force such as an impact is applied. 1 rotates.
When a rotation shift occurs in the multi-beam light source unit 1, the line interval adjusted with high accuracy is out of order, and the image performance deteriorates. Therefore, a groove 11b is provided on the side edge of the laser holder 11a, and the tip of a fixing screw 8e, which is a rotation preventing means (screw member) supported by the protrusion of the side wall 8a of the optical box 8, is inserted into the groove 11b of the laser holder 11a. Press. Even if the laser holder 11a tries to rotate due to an impact or the like, there is no danger of rotational displacement occurring because the fixing screw 8e is engaged with the groove 11b of the laser holder 11a.

Note that a projection may be provided instead of providing the groove on the side edge of the laser holder, and a fixing screw may be pressed against the projection.

As described above, by providing the rotation preventing means such as the fixing screw in addition to the fastening means such as the screw, the multi-beam light source unit after the rotation adjustment is firmly fixed to the optical box, and the disturbance such as an impact is provided. Of the rotation of the multi-beam light source unit due to the above.

By simply adding a simple member such as a fixing screw, it is possible to realize a high-performance light beam scanning device in which even if an impact or the like is applied, the line interval adjusted with high precision does not change.

FIG. 5 shows a second embodiment. this is,
Instead of using a fixing screw as the rotation preventing means, a laser holder 21a for holding the multi-beam semiconductor laser 21
Is provided with a through hole 21b, and a boss 38e protruding from the side wall 38a of the optical box 38 is connected to the through hole 2 of the laser holder 21a.
1b. As described above, the laser holder 21a is rotated with respect to the optical box 38 to adjust the line interval, and then the adhesive 38f is poured into the through-hole 21b and hardened. The cured adhesive 38f adheres and fixes the laser holder 21a to the optical box 38, and constitutes a rotation preventing means for preventing the laser holder 21a after line spacing adjustment from being rotated by a disturbance such as an impact.

The operation of pouring and curing the adhesive 38f may be performed before or after the laser holder 21a is fastened to the side wall 38a of the optical box 38 by the screw 38c.

FIG. 6 shows a third embodiment. this is,
An adjusting screw 58e, which is an adjusting means, is held at the protruding portion of the side wall 58a of the optical box 58, and its tip is connected to the semiconductor laser 41.
Is screwed into the screw hole 41b of the laser holder 41a that holds the laser beam, and by rotating the adjustment screw 58e,
The rotation of the laser holder 41a can be adjusted.

In the line spacing adjustment operation, the adjustment screw 58e is turned to rotate the laser holder 41a, and the rotation of the adjustment screw 58e is stopped when the laser array reaches a predetermined inclination angle.

Subsequently, the screw 58c is tightened and the optical box 5 is tightened.
8, the laser holder 41a is fastened. In this state, the adjusting screw 58e constitutes a rotation preventing means for preventing the laser holder 41a from rotating due to an impact or the like.

That is, the adjusting screw for performing the adjusting operation with high precision also serves as the rotation preventing means, and has the added advantage that the efficiency of the adjusting operation can be improved.

[0041]

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

After adjusting the line spacing of a plurality of laser beams emitted from the multi-beam semiconductor laser and fastening the multi-beam light source unit to the optical box, the multi-beam light source unit is rotated by a disturbance such as an impact. To prevent the line interval and the like from changing. Thereby, the reliability of the device can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a light beam scanning device according to a first 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 sectional view showing a multi-beam light source unit.

FIG. 4 is a diagram illustrating an operation of adjusting a line interval.

FIG. 5 is a diagram showing a second embodiment.

FIG. 6 is a diagram showing a third embodiment.

FIG. 7 is a schematic perspective view showing a light beam scanning device according to a conventional example.

FIG. 8 is a sectional view showing a multi-beam light source unit of the apparatus of FIG.

FIG. 9 is a diagram illustrating an operation of adjusting a line interval in the apparatus of FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multi-beam light source unit 2 Cylindrical lens 3 Rotating polygon mirror 4 Imaging lens 8, 38, 58 Optical box 8a, 38a, 58a Side wall 8b Fitting hole 8c, 38c, 58c Screw 8e Fixing screw 11, 21, 41 Multi-beam semiconductor Laser 11a, 21a, 41a Laser holder 11b Groove 12 Collimator lens 12a Lens barrel 38f Adhesive 58e Adjustment screw

Claims (5)

[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. Imaging means, a housing provided with a fitting portion for rotatably supporting the multi-beam light source unit, and a rotation preventing means for preventing a rotational displacement after adjusting a rotation angle of the multi-beam light source unit, A light beam scanning device having a fastening means for fastening the multi-beam light source unit to the housing. 2. The light beam scanning device according to claim 1, wherein the rotation preventing means has a screw member pressed against a groove or a protrusion of the multi-beam light source unit. 3. The light beam scanning device according to claim 1, wherein the rotation preventing means has an adhesive for bonding the multi-beam light source unit to the housing. 4. An apparatus according to claim 1, wherein the adjusting means for adjusting the rotation angle of the multi-beam light source unit with respect to the fitting portion of the housing also serves as the rotation preventing means.
The light beam scanning device according to claim 1. 5. The light beam scanning device according to claim 1, wherein the laser holder is integrated with a lens barrel holding the collimator lens.