JP2000275558A - Optical deflecting scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and speedily incorporate a multibeam light source unit and adjust a line interval. SOLUTION: When a laser holder 11a holding a multibeam semiconductor laser 11 is built in a base 14, the line interval needs to be adjusted by rotating the laser holder 11a. For the purpose, loose fit is set to the state being ϕA<ϕB at room temperature and ϕA>ϕB at the temperature raised by a heater H1, where ϕA is the internal diameter of an engagement hole 14b of the base 14 and ϕB is the external diameter of an engagement part 11b of the laser holder 11a. In the temperature-raised state of the loose fit, the laser holder 11a is rotated to adjust the line interval and after the temperature is put back to the room temperature, they are fixed in a shrink fit state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical deflection scanning apparatus having a multi-beam writing optical system using a plurality of laser beams in a laser beam printer, a digital copying machine, or the like.

[0002]

2. Description of the Related Art An image information writing optical system used in a laser beam printer, a digital copying machine, a laser facsimile, and the like, uses a laser beam deflected and scanned by a rotating polygon mirror rotating at a high speed by using an imaging lens or the like. An image is formed on the photosensitive member on the drum. A point image (spot) formed on the photoconductor forms a two-dimensional electrostatic latent image by main scanning by rotation of a rotating polygon mirror and sub-scanning by rotation of a photosensitive drum. Thereafter, a hard copy is output by a known electrophotographic recording technique, and printing (printing) and the like are performed.

In recent years, with the demand for higher print output and higher recording density, the rotational speed of the rotary polygon mirror tends to be higher. However, when the rotation speed of the rotary polygon mirror is as high as 30,000 rpm or more, it is not easy to solve the problems of vibration and noise.

Therefore, a technique for simultaneously scanning two lines using a multi-beam light source having two light-emitting points has been developed as another corresponding means. This means that the printing speed and recording density can be reduced by two without changing the rotation speed of the rotating polygon mirror.
The future is expected as a multi-beam writing optical system that can be doubled.

When a multi-beam light source such as a multi-beam semiconductor laser having two or more light-emitting points is used, a plurality of scanning lines scanned on the photosensitive drum by a plurality of laser beams emitted from the light-emitting points. It is necessary to adjust to the interval. As one of the means, there is a method of rotating and adjusting a multi-beam semiconductor laser.

More specifically, first, a base having an annular support centered on the optical axis of the multi-beam semiconductor laser is fixed to a housing for supporting a rotary polygon mirror or the like of the optical deflection scanning device. The multi-beam semiconductor laser is held by a laser holder, and the laser holder is fitted to an annular support portion of the base, so that the laser holder is rotatable around a central axis of the annular support portion. .

A rotary polygon mirror is driven to rotate, a multi-beam semiconductor laser emits light to form a plurality of scanning lines,
The interval between the plurality of scanning lines, that is, the line interval is detected by the detecting means, and the laser holder is rotated so that the line interval becomes a predetermined value. When the predetermined value is obtained, the laser holder is screwed to the base or the like. Fixed by.

[0008]

However, according to the above prior art, there are the following unsolved problems.

(1) When a laser holder is fitted to a fitting portion (supporting portion) such as a base and the fitting portion is rotated as a guide, there is generally a few gaps between the laser holder and the fitting portion. 1
Since there is a gap of 0 μm, the laser holder rattles and staggers due to the gap while rotating. If there is such a fluctuation, a fixed mutual relationship is not established between the position of the scanning line and the rotation angle of the laser holder, and it takes time to adjust the line interval.

(2) To fix the laser holder to the base at a predetermined rotation position, fastening is performed with screws. However, during the fastening operation for rotating the screws, the laser holder rotates together with the screws, causing adjustment failure. Easy to occur. If adjustment is lost, readjustment is required, and the work efficiency is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and can perform a work for adjusting a line interval of a multi-beam with high accuracy, quickly and easily. An object of the present invention is to provide an optical deflection scanning device which does not require fastening means such as screws and can greatly contribute to simplifying an assembling process and reducing the number of assembled parts.

[0012]

To achieve the above object, an optical deflection scanning apparatus according to the present invention comprises a multi-beam semiconductor laser for generating a plurality of laser beams, a laser holder for holding the multi-beam semiconductor laser, Scanning image forming means for scanning the laser beam to form an image on an image forming surface, and a light source supporting member for supporting the laser holder, wherein the light source supporting member rotates the laser holder in a predetermined temperature rising state. It is characterized in that it comprises a supporting portion which is fitted freely and fixedly supports the laser holder at a normal temperature by a shrink fit.

A multi-beam semiconductor laser for generating a plurality of laser beams, a laser holder for holding the plurality of laser beams, a scanning image forming means for scanning each of the plurality of laser beams to form an image on an image forming surface; The laser holder, the laser holder is rotatably fitted to the support portion of the housing in a predetermined temperature rising state, and at a normal temperature to the support portion of the housing. The light deflection scanning device may include a fitting portion configured to be fixed by a shrink fit.

The material of the fitting portion of the laser holder may be different from the material of the remaining portion excluding the fitting portion.

[0015] The housing may be an optical box containing a scanning image forming means.

[0016]

When assembling a multi-beam light source unit including a multi-beam semiconductor laser and a laser holder to a light source supporting member, the supporting portion is heated to a temperature rising state, and the laser holder is rotated to separate a plurality of laser beams from each other. Do the work of adjusting. When the adjustment operation is completed, the heating of the light source support member is stopped and the temperature is returned to room temperature, and the laser holder is fixed to the light source support member by a shrink fit by cooling and shrinking.

When the multi-beam light source unit is directly mounted on a housing such as an optical box without interposing a light source supporting member, the fitting portion of the laser holder over the supporting portion of the housing is heated and raised. With the temperature maintained, the laser holder is rotated to adjust the line spacing. The temperature is returned to room temperature, the laser holder is cooled and contracted, and fixed by shrink fit.

Only the fitting portion of the laser holder is made of a material such as a synthetic resin which is easily thermally expanded, and the remaining portion is made of a metal which easily secures rigidity and dimensional accuracy for stably holding the multi-beam semiconductor laser. Is also good.

After adjusting the line interval, compared to the case where the laser holder is fastened to the housing or the light source support member by using a screw or the like, there is no trouble such as adjustment collapse due to co-rotation when fastening the screw, and the line interval can be reduced. The time spent for adjustment work can be greatly reduced.

The assembly process is simplified, the assembly is performed quickly, and the number of parts to be assembled can be significantly reduced by omitting screws and the like.

Since there is no need to secure a space for a tool for fastening a screw, there is an advantage that the entire light source unit can be reduced in size.

This can greatly contribute to downsizing of the apparatus and reduction of the manufacturing cost.

[0023]

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

FIG. 1 shows an optical deflection scanning apparatus according to a first embodiment, which is composed of a multi-beam semiconductor laser 11 as a light source of a multi-beam light source unit 1 and a laser beam P as two light beams. ₁ and P ₂ are generated,
After being collimated by the collimator lens 12, the light is radiated to the reflecting surface of the rotary polygon mirror 3 through the cylindrical lens 2, and passed through the image forming lens system 4 which forms a scanning image forming means together with the rotary polygon mirror 3, and the photosensitive drum 5 The image is formed on the photoreceptor which is the image forming surface.

The two laser beams P ₁ and P ₂ are incident on the reflecting surface of the rotary polygon mirror 3 and are respectively scanned in the main scanning direction. The main scanning in the Y-axis direction by the rotation of the rotary polygon mirror 3 and the photosensitive drum 5 An electrostatic latent image is formed on the photoconductor along with the sub-scan in the Z-axis direction due to the rotation of.

The cylindrical lens 2 condenses the laser beams P ₁ and P ₂ linearly on the reflection surface 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 system 4 includes a spherical lens 4a. And the toric lens 4b have the function of preventing the distortion of the point image on the photoconductor, similarly to the cylindrical lens 2, and correct the point image so that the point image is scanned on the photoconductor at a constant speed in the main scanning direction. It has a function to do.

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) and pass through a condenser lens 7a on the opposite side of the main scanning plane to the optical sensor 7. Is converted into a write start signal by a controller (not shown) and transmitted to the multi-beam semiconductor laser 11. Multi-beam semiconductor laser 11
Receive the write start signal and receive the laser beams P ₁ , P ₂
Starts write modulation.

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 photosensitive member on the photosensitive drum 5 is controlled. .

Note that only the preceding laser beam may be detected by the optical sensor 7, and the modulation timing of the subsequent laser beam may be controlled with a certain time difference.

A cylindrical lens 2, a rotating polygon mirror 3,
The imaging lens system 4 and the like are assembled to the frame 8 shown in FIG.

The multi-beam semiconductor laser 11 has the above-described structure.
So that multiple laser beams P₁ , P _Two Flash at the same time
And a collimator lens via a laser holder 11a.
Unit 12 integrally connected to a lens barrel 12a containing
The light source support section together with the laser drive circuit board 13
It is assembled on a base 14 which is a material.

The assembly of the multi-beam light source unit 1 is performed by adjusting the focus of the collimator lens 12 by placing the lens barrel 12a of the collimator lens 12 on the laser holder 11a to which the multi-beam semiconductor laser 11 is fixed by a known method such as press-fitting or bonding. After three-dimensional adjustment such as optical axis alignment and the like, the lens barrel 12a is bonded to the laser holder 11a.

When assembling the multi-beam light source unit 1 to the base 14, it is necessary to rotate the multi-beam light source unit 1 to adjust the line interval between the laser beams P ₁ and P ₂ . Therefore, the cylindrical portion 14 of the base 14
a is provided with a fitting hole 14b as a support portion and a reference surface 14c orthogonal to the center axis thereof, and heats the cylindrical portion 14a of the base 14, expands the inner diameter of the fitting hole 14b by thermal expansion, The laser holder 1 is brought into a temperature rising state of a clearance fit in which the fitting portion 11b of the laser holder 11a is rotatably fitted.
1a into the fitting hole 14b, and
The contact portion 11c of the laser holder 11a is brought into contact with the reference surface 14c. In this state, an adjustment operation for rotating the laser holder 11a to an angle to obtain a predetermined line interval is performed.

When the heating of the base 14 is stopped and returned to room temperature after the adjustment work, the laser holder 11a can be fixed to the base 14 by a so-called shrink fit by cooling and shrinking the cylindrical portion 14a.

More specifically, the fitting hole 14 of the base 14
The relationship of φA <φB is established at room temperature between the inner diameter dimension φA of b and the outer diameter dimension φB of the fitting portion 11b of the laser holder 11a fitted into the fitting hole 14b. . When assembling the laser holder 11a to the base 14, the line spacing is adjusted as follows.

Firstly, heating the cylindrical portion 14a of the base 14 with the heater H _1, such as a high-frequency heater. At this time, the heater H ₁ is heated so that only the vicinity of the fitting hole 14b is heated.
Is brought into contact with the fitting hole 14b as close as possible. The fitting hole 14b is heated and expanded by thermal expansion so that its inner diameter φA becomes larger than the outer diameter φB of the fitting part 11b of the laser holder 11a. The fitting hole 14 of the base 14
b, and the contact portion 11c of the laser holder 11a is brought into contact with the reference surface 14c. By controlling the temperature of the heat generating portion of the heater H _1, slightly larger than the outer diameter φB of the fitting portion 11b inner diameter φA of the laser holder 11a of the fitting hole 14b, for example, gap having a clearance of several μm It can be in a fit state. As a result, the fitting hole 14b of the base 14 and the fitting portion 14b of the laser holder 11a are rotatably fitted to each other in a state where there is very little play.

The contact portion 11c of the laser holder 11a
It is necessary that both the reference surface 14c of the base 14 and the reference surface 14c have a high degree of perpendicularity to the optical axis.

Next, the multi-beam semiconductor laser 11 emits light while rotating the rotary polygon mirror 3, and the laser beam P
_1, to form a plurality of scan lines by P _2. A screen is provided on a scanning surface on which the laser beams P ₁ and P ₂ are focused to form a spot, that is, at a position corresponding to the surface of the photosensitive member of the photosensitive drum 5, and an objective lens and a camera are provided behind the screen. The distance between the scanning lines in the sub-scanning direction, that is, the line interval is detected, and the laser holder 11a is rotated to a predetermined value to adjust the line interval.

When the line interval reaches a predetermined value,
Lowering the temperature of the heat generating portion of the heater H ₁ that heating the cylindrical portion 14a of the base 14. As a result, the cylindrical portion 14a of the base 14
Is shrunk, and its inner diameter φA tends to return to its original size.
The laser holder 11a is firmly fixed to the base 14 by a so-called shrink fit.

In the present embodiment, as described above, the inner diameter of the fitting portion provided in the laser holder and the outer diameter of the fitting hole provided in the laser holder are normally in a shrink fit relationship.
When adjusting the line interval by fitting both, the base is temporarily heated. In this way, the fitting hole of the base is thermally expanded and fitted with a very small gap of about several μm between the fitting hole of the laser holder and the laser holder. Make adjustments. When the line interval becomes a predetermined value, the base is returned to room temperature and contracted to firmly fix the laser holder to the base.

In the step of adjusting the rotation using the fitting portion of the laser holder as a guide, there is only a gap of several μm at the fitting portion, and there is very little backlash, so that the laser holder fluctuates and rotates as in the conventional example. Never do. Therefore, it is easy to adjust the line interval without shifting the position of the scanning line due to the fluctuation of the laser holder.

Further, when the laser holder is fixed to the base after the adjustment, the fixing is performed by a shrink fit which does not require any fastening work such as screwing or the like and does not apply an external force in the direction of rotating the laser holder. Therefore, there is no possibility that the adjustment may be lost.

The operation of adjusting the line spacing of a plurality of laser beams can be performed quickly and with high precision, which can greatly contribute to higher precision and lower cost of the optical deflection scanner.

As the material of the laser holder, a metal material such as zinc die-casting is often used when heat radiation of the light emitting portion is required, and a reinforced resin containing glass fiber is generally used in terms of rigidity and dimensional accuracy. It is commonly used. On the other hand,
The material of the base is a non-reinforced resin from the viewpoint of the function, and the thermal expansion coefficient of the base is generally much larger than the thermal expansion coefficient of the laser holder. In the present embodiment, the base having the larger thermal expansion coefficient is heated so that the shrink fit is performed at a lower heater temperature.

In this embodiment, since the base is a single-function member used only for holding the laser holder, there is an advantage that an access space for the heater can be easily secured around the base.

Further, the fixing by the shrink fit does not require a fastening member such as a screw, so that the required number of parts can be reduced. Further, there is no need to secure an extra working space for fastening work of screws and the like, and there is a great advantage in terms of space saving, that is, miniaturization.

FIG. 3 shows a second embodiment. this is,
The rotating polygon mirror 3 and the like are built in an optical box 28 as a housing, and the multi-beam light source unit 2 is directly provided on a side wall 28a of the optical box 28.
In this configuration, a fitting portion 28b, which is a cylindrical support portion, protrudes from a side wall 28a of the optical box 28, and the fitting portion 28b is attached to the multi-beam semiconductor laser 31.
Hole 3 which is a fitting portion of laser holder 31a for holding
1b is fitted by the same shrink fit as in the first embodiment.

More specifically, the laser holder 31a is provided with a fitting hole 31b coaxial with the hole for holding the multi-beam semiconductor laser 31, and the side wall 28a of the optical box 28 is provided with a laser beam incident on the rotary polygon mirror 3. The fitting portion 28b having the optical path as a central axis is provided. Optical box 2
A reference surface 28c for contacting the contact portion 31c of the laser holder 31a is provided on a side surface of the laser holder 8, and both surfaces are finished to a high-precision flatness in order to obtain a right-angle accuracy with respect to the central axis.

Outer diameter φC of fitting portion 28b of optical box 28
And the inner diameter φD of the fitting hole 31b of the laser holder 31a.
Are configured such that the relationship of φC> φD is established at room temperature.

The rotary polygon mirror 3, the collimator lens 12 and the like are the same as those in the first embodiment, and are represented by the same reference numerals.
Description is omitted. Next, the multi-beam light source unit 21
The method of fixing the optical disk to the optical box 28 after adjusting the rotation will be described.

Firstly, heating the outer peripheral portion of the laser holder 31a with a heater of H ₂ such as a high-frequency heater. At this time,
The heating portion of the heater H ₂ to heat only the vicinity of the fitting hole 31b is as close as possible to the fitting hole 31b. Heating causes the fitting hole 31b of the laser holder 31a to thermally expand, and the inner diameter φD of the fitting hole 31b becomes equal to the outer diameter φ of the fitting portion 28b of the optical box 28.
It becomes larger than C. Here, by controlling the temperature of the heater H ₂ , the inside diameter φD of the fitting hole 31 b of the laser holder 31 a becomes the outside diameter φ of the fitting portion 28 b of the optical box 28.
The gap is slightly larger than C, for example, several μm. That is, the fitting portion 28b of the optical box 28 and the fitting hole 31b of the laser holder 31a are fitted in a clearance-fitted state with an extremely small gap, and the contact portion 31c of the laser holder 31a is fitted to the reference surface 28c of the optical box 28. Abut

Next, the multi-beam semiconductor laser 21 emits light with the rotating polygon mirror 3 being rotated, thereby forming a plurality of scanning lines. A gap in the sub-scanning direction of a plurality of spots being scanned, that is, a line interval is detected, and adjustment is performed by rotating the laser holder 31a so that the gap becomes a predetermined value. Lowering the temperature of the heater H ₂ that heat the laser holder 31a upon reaching a predetermined line interval.
As a result, the fitting hole 31b of the laser holder 31a contracts, and its inner diameter dimension D attempts to return to the original dimension. As a result, the fitting hole 31b of the laser holder 31a is
8, the laser holder 31a is firmly fixed to the optical box 28 by a so-called shrink fit.

In this embodiment, as in the first embodiment, the operation of adjusting the line interval can be performed quickly with high accuracy.

As the material of the optical box, a reinforced resin containing glass fiber is used from the viewpoint of rigidity and dimensional accuracy required for the optical box. Generally, the laser holder has a larger thermal expansion coefficient. Therefore, when the laser holder having a larger thermal expansion coefficient is heated, the shrink fit can be performed at a lower temperature. The other points are the same as in the first embodiment.

FIG. 4 shows a modification of the second embodiment. This is the same as the laser holder 31a, except that the outer peripheral portion 41c having the fitting hole 41b of the laser holder 41a is made of resin, and the remaining main body portion 41d is made of metal.

By using a metal material having good heat dissipation and high rigidity for the main body portion 41d for holding the multi-beam semiconductor laser 41, dimensional accuracy and the like are ensured, while thermal expansion occurs on the outer peripheral portion 41c of the laser holder 41a. An additional advantage is that a resin material having a large coefficient can be used to perform a clearance fit with the fitting hole 41b at a low heating temperature.

[0057]

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

The operation of adjusting the line interval of the multi-beam can be performed quickly and easily with high accuracy.
Since fastening means such as screws are not required, it is possible to greatly contribute to simplification of the assembling process, reduction of the number of assembled parts, and downsizing of the apparatus.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view illustrating an optical deflection scanning device according to a first embodiment.

FIG. 2 is a partial sectional view showing a main part of the apparatus of FIG.

FIG. 3 is a partial sectional view showing a main part of a second embodiment.

FIG. 4 is a partial sectional view showing a modification of the second embodiment.

[Explanation of symbols]

 1, 21 Multi-beam light source unit 2 Cylindrical lens 3 Rotating polygon mirror 4 Imaging lens system 5 Photosensitive drum 8 Frame 11, 31, 41 Multi-beam semiconductor laser 11a, 31a, 41a Laser holder 11b, 28b Fitting part 12 Collimator lens 12a Lens tube 14 Base 14b, 31b, 41b Fitting hole 28 Optical box 41c Outer periphery 41d Main body

Claims (4)

[Claims] 1. A multi-beam semiconductor laser for generating a plurality of laser beams, a laser holder for holding the same,
Scanning image forming means for scanning each of the plurality of laser beams to form an image on an image forming surface; and a light source supporting member for supporting the laser holder, wherein the light source supporting member is a laser light source in a predetermined temperature rising state. An optical deflection scanning device, comprising: a holder configured to rotatably fit a holder and fixedly support the laser holder by shrink fitting at room temperature. 2. A multi-beam semiconductor laser for generating a plurality of laser beams, a laser holder for holding the multi-beam semiconductor laser,
Scanning imaging means for scanning each of the plurality of laser beams to form an image on an image forming surface, and a housing having a support portion for supporting the laser holder, wherein the laser holder is in a predetermined temperature rising state. And a fitting portion configured to be rotatably fitted to the support portion of the housing and to be fixed to the support portion of the housing by a shrink fit at normal temperature. Light deflection scanning device. 3. The optical deflection scanning device according to claim 2, wherein a material of a fitting portion of the laser holder is different from a material of a portion other than the fitting portion. 4. The light deflection scanning device according to claim 2, wherein the housing is an optical box containing a scanning image forming means.