JPH11202232A - Multibeam scanning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multibeam scanning device in which the irradiating position, focusing position and sub-scanning pitch or the like of a laser unit are not fluctuated in the state of high or low temperature. SOLUTION: This device is constituted by providing the laser unit composed of a semiconductor laser 1 having plural light emitting points, a holder 3 for holding the semiconductor laser 1 and a collimator lens 5 for making emitted beams almost parallel, a deflector for deflecting the laser beams emitted from this laser unit and various lenses for deflecting and scanning a photosensible body and attaching these components to an optical box 6. In this case, the holder 3 for holding the semiconductor laser 1 of the said laser unit and the optical box 6 are formed from the material of almost the same thermal expansion coefficient.

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 optical writing in a laser printer, a digital copying machine, or the like.

[0002]

2. Description of the Related Art General multi-beam laser unit 1
10 is shown in FIGS. The semiconductor laser 101 having a plurality of light emitting points is fixed to the fitting hole 109 of the holder 102 by press-fitting or bonding. Then the collimator lens 20
2. The lens barrel 103 containing the aperture 201 is adjusted in the XYZ directions, and is then adhesively fixed to the holder 102 by a known technique (for example, reference number 2198028). In this manner, the laser unit 110 that has been adjusted is now shown in FIG.
When fixing to the optical box 106 in which the optical parts in, for example, the Fθ lens F, the rotating polygon mirror R, etc. are attached,
As shown in FIG. 5, in order to adjust the interval between the spots 40 at a predetermined pitch (sub-scanning direction), that is, the D pitch, it is necessary to perform rotation adjustment in the AA ′ direction shown in FIG. For example, D
Pitch is about 42μm at 600DPI, 1200DP
In the case of I, a very fine pitch of about 21 μm needs to be adjusted to about ± several μm. After the rotation adjustment in the AA ′ direction as described above, the laser unit 110 is fixed to the optical box 106 with the screw 105 through the elongated hole 104 provided in the holder 102 with respect to the female screw 107 provided in the optical box 106. You.

[0003]

However, the above-mentioned prior art has the following disadvantages. After adjusting the sub-scanning pitch, the laser unit (holder) is fixed to the optical box with screws etc. If the thermal expansion coefficient of the holder and the optical box are different, the difference in thermal expansion between the holder and the optical box at high or low temperature Irradiation position, focus position,
There was a problem that the sub-scanning pitch fluctuated. The variation of the sub-scanning pitch is described as follows. For example, if the sub-scanning pitch is about 21 μm and the main scanning pitch is about 1.5 mm on the photoconductor, if the sub-scanning pitch fluctuates by 2 μm (10% fluctuation), the interval between the two light emitting points of the semiconductor laser does not change. The main scanning pitch is changed by 10%. That is, the main scanning pitch is 150 μm.
m. In this scanning device, if only one of the BD (beam detection; writing position detection) is taken, the writing position of the other will vary by 150 μm. For this reason, in the case of the conventional example, there is a problem that a dot position shift on the photoconductor causes a high quality image to not be provided.

Accordingly, the present invention has been made to solve the above-mentioned problems in the prior art, and to provide a multi-beam scanning apparatus in which the irradiation position, focus position, sub-scanning pitch and the like of a laser unit do not fluctuate in a high or low temperature state. It is an object.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a semiconductor laser having a plurality of light emitting points, a holder for holding the semiconductor laser, and a collimator lens for making the emitted beam substantially parallel light. A multi-beam scanning device comprising a laser unit having the above configuration, a deflector for deflecting laser light emitted from the laser unit, and various lenses for deflecting and scanning a photosensitive member, and attaching these to an optical box. Wherein the holder for holding the semiconductor laser of the laser unit and the optical box are formed of materials having substantially the same coefficient of thermal expansion.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, since the thermal expansion coefficient of the holder and the optical box are made of substantially the same material, the laser unit is attached to the optical box after rotation adjustment of the laser unit (holder) for adjusting the sub-scanning pitch. Even when the temperature is high or low, no external force such as expansion or contraction of the optical box is applied to the holder while the optical unit is fixed with screws, adhesive, etc., so that the irradiation position, focus position and sub-scanning pitch of the laser unit do not change. A beam scanning device can be configured.

[0007]

An embodiment of the present invention will be described with reference to FIG. In FIG. 1, a semiconductor laser 1 is fixed to a holder 3 by bonding or press-fitting. Thereafter, the lens barrel 4 holding the collimator lens 5 is moved and adjusted to a predetermined position in the XYZ directions, and then bonded. With this adjustment, the mechanical adjustment in the laser unit is completed. Also, when the adjusted laser unit 110 is mounted on the optical box 6, the holder 3 is fitted by fitting the fitting portion 8 provided on the holder 3 into the fitting hole 7 provided on the optical box 6. It is positioned in the optical box 6.

Thereafter, the sub-scanning pitch is adjusted by rotating the laser unit 110 in the BB 'direction. B
The rotation adjustment in the direction B ′ is performed by fitting the rotation adjustment pin 11 provided on the rotation adjustment jig 13 into the rotation adjustment hole 10 provided on the holder 3 and rotating the rotation adjustment jig 13. Let me do it. At the pitch corresponding to a predetermined DPI (resolution), the rotation adjustment is completed, and the screw 9 is screwed into the fixing hole 10 provided in the holder 3 into the female screw 14 provided in the optical box 6 to thereby fix the holder 3. Is fixed to the optical box 6.

Considering the materials of the holder 3 and the optical box 6 of the laser unit 110 assembled and adjusted in this way, for example, the optical box 6 is made of PC (polycarbonate) containing 30 to 50% of glass. Is easy. Further, it is possible to make the holder 2 of a similar material in recent resin scanning lenses. this is,
In a resin scanning lens, the refractive index changes due to a change in temperature, so that a phenomenon occurs that the focal position changes. However, if the thermal expansion of the holder 2 is positively used, the above-described shift of the focal position is canceled, and the focus position is changed. This is because the displacement can be made very small.

[0010]

As described above, according to the present invention,
By making the holder for holding the semiconductor laser of the laser unit and the optical box substantially the same in thermal expansion coefficient, in a high-temperature or low-temperature state, an external force of expansion and contraction due to a difference in thermal expansion between the two is applied to the holder. It is possible to realize a multi-beam scanning apparatus capable of forming a high-quality image in which the irradiation position, the focus position, and the sub-scanning pitch of the laser unit do not change without any addition.

[Brief description of the drawings]

FIG. 1 is an external view of a multi-beam laser unit according to a first embodiment of the present invention.

FIG. 2 is an external view of a general multi-beam laser unit.

FIG. 3 is a cross-sectional view of a general multi-beam laser unit.

FIG. 4 is an external view of a general multi-beam scanning device.

FIG. 5 is an enlarged view of a sub-scanning interval of a spot.

[Explanation of symbols]

 1: Semiconductor laser 3: Holder 4: Lens barrel 5: Collimator lens 6: Optical box 7: Fitting hole 8: Fitting part 9: Screw 10: Fixing hole 11: Rotation adjustment pin 12: Rotation adjustment hole 13 ： Rotation adjustment jig

Claims (1)

[Claims] 1. A laser unit comprising a semiconductor laser having a plurality of light emitting points, a holder for holding the semiconductor laser, and a collimator lens for making the emitted beam substantially parallel light, and a laser emitted from the laser unit. In a multi-beam scanning apparatus comprising a deflector for deflecting light and various lenses for deflecting and scanning a photoconductor, and attaching them to an optical box, a holder for holding a semiconductor laser of the laser unit and the optical box Are formed of materials having substantially the same coefficient of thermal expansion.