JP2002258188A - Laser scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser scanner whose manufacturing cost is reduced by improving the assembly efficiency while maintaining the accuracy of the mounting position of an optical device. SOLUTION: Parts such as a light source part 20, a cylindrical lens 30, a deflecting part 40 and a scanning lens 50 are directly mounted on a flat plate- like main body base plate 10 which is formed of a steel late and to which bending work is not applied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a laser scanning device provided in a digital image forming apparatus or the like.

[0002]

2. Description of the Related Art Conventionally, in a laser scanning apparatus used for exposing a photosensitive drum in an electrophotographic digital copying machine or a laser printer, a laser beam emitted from a light source such as a semiconductor laser is converted into a polygon. The mirror is deflected in the main scanning direction by a deflecting device including a mirror and a polygon motor that rotationally drives the mirror, and is configured to expose and scan the surface to be scanned through a scanning optical system including a scanning lens.

In this type of laser scanning device, components constituting the laser scanning device, such as the light source, the deflecting device, and the scanning optical system, are installed in a housing and configured as one unit. Such a housing is usually formed in a box shape by injection-molding a resin, and particularly in a portion where the components of the laser scanning device are installed, an optical positional relationship after the installation of the components is predetermined. It is formed in a complicated manner so that the relationship

[0004]

However, in the laser scanning device, since it is necessary to install each optical element within a range of an error of only a few μm, high processing accuracy is required for the housing, and as described above. In addition, it takes a great deal of time to attach the optical element to a complicated installation portion of the housing while finely adjusting the optical element to an accurate position, and it takes much time to assemble the laser scanning device.

[0005] In recent years, in the above-described laser scanning device, the cost of its components has been reduced, and a large part of the manufacturing cost of the laser scanning device is occupied by the labor costs of workers involved in the manufacturing. It has become. Therefore,
The effect of the assembly efficiency of the laser scanning device on the manufacturing cost is very large. The present invention has been made in view of the above problems, and has as its object to provide a laser scanning device capable of maintaining high accuracy and improving the efficiency of assembling the laser scanning device.

[0006]

In order to achieve the above object, a laser scanning device according to the present invention deflects a laser beam emitted from a light emitting element by a deflecting means, and scans the surface to be scanned via a scanning optical element. , Wherein the light emitting element, the deflecting means, and the scanning optical element are directly mounted on the same surface of a metal flat plate.

Further, the present invention is characterized in that the deflecting means comprises a polygon mirror and a motor for rotating the polygon mirror, and the motor is formed integrally with the metal plate. Further, the present invention has a first drive circuit for driving the light emitting element and a second drive circuit for driving the deflecting means, wherein at least one of the first and second drive circuits is formed of the metal. It is characterized by being provided on a flat plate.

Further, according to the present invention, the first and / or second driving circuit provided on the metal flat plate may be provided on a peripheral portion of the flat plate on the flat plate remote from the scanning optical element and the light emitting element. It is characterized by being arranged. Further, the present invention is characterized in that the metal flat plate has a vibration damping structure.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the laser scanning device according to the present invention will be described with reference to the drawings. Figure 1
1 is a schematic perspective view showing an overall configuration of a laser scanning device 1 according to an embodiment of the present invention.

As shown in FIG. 1, the laser scanning device 1 comprises:
A light source unit 20, a cylindrical lens 30, and a deflecting unit 4 are placed on a flat main body substrate 10 that has not been subjected to bending or the like.
0, scanning lens 50, reflection mirror 60, SOS sensor 7
0, laser drive circuit 100, polygon motor drive circuit 2
00 and the synchronization signal processing circuit 300 are directly attached.

Here, the laser driving circuit 100, the polygon motor driving circuit 200 and the synchronous signal processing circuit 3
In the case of 00, the electronic components are actually mounted on the main substrate 10, but only the area of each circuit board is shown by oblique lines to avoid complication. Such a simple flat main body substrate 1
By mounting the components of the laser scanning device 1 directly on the laser scanning device 0, workability in assembling the laser scanning device can be improved, and assembling efficiency can be improved.

Further, since the main body substrate 10 is a steel plate, expansion and shrinkage due to a temperature change of the surrounding environment and the like are small as compared with the case of a housing made of resin or the like.
There is an effect that the laser beam can be scanned under extremely stable conditions with little change in the optical positional relationship among the cylindrical lens 30, the deflecting unit 40, and the scanning lens 50.

The mounting holes 11 to 14 formed at the four corners of the main body substrate 10 are for fixing the laser scanning device 1 to a main body of an image forming apparatus or the like via bolts or the like. The light source unit 20 includes a semiconductor laser 21 that emits a laser beam, and a collimator lens 2 that converts the laser beam emitted from the semiconductor laser 21 into parallel light.
2 is press-fitted or adhered into a mounting hole of the light source holder 23 having a “U” shape.

The cylindrical lens 30 focuses the laser beam emitted from the semiconductor laser 21 only in the sub-scanning direction for so-called surface tilt correction. Deflection unit 4
Numeral 0 denotes a polygon mirror 42 and a polygon motor 41 for rotating the polygon mirror 41. The laser beam transmitted through the cylindrical lens 30 is reflected by the mirror surface on the side of the polygon mirror 42, which is rotated in a predetermined direction by the polygon motor 41. The light is reflected and deflected in the main scanning direction.

The scanning lens 50 is designed such that the laser beam deflected by the deflecting unit 40 scans the surface to be scanned at a constant speed by passing through the scanning lens 50. The reflection mirror 60 reflects a laser beam (hereinafter, referred to as a “synchronous detection beam”) emitted from the semiconductor laser 21 at a predetermined timing in order to acquire a write synchronization signal for each scanning line on the surface to be scanned. The light is incident on the light receiving surface of the SOS sensor 70. This SO
The S sensor 70 is a photoelectric sensor for detecting the synchronization detection beam reflected by the reflection mirror 60, and outputs the detection result to the synchronization signal processing circuit 300.

A laser drive circuit 100 for modulating and driving the semiconductor laser 21, a polygon motor drive circuit 200 for rotating and driving the polygon motor 41 in the deflecting section 40, and the SOS sensor 7 are provided in the peripheral area of the main body substrate 10.
A synchronization signal processing circuit 300 is provided for processing the detection result output from 0 as a write synchronization signal for each scanning line on the scanned surface.

In the main substrate 10, the deflecting section 40,
Laser drive circuit 100, polygon motor drive circuit 200
The portion of the synchronization signal processing circuit 300 where the electric component is mounted is coated in advance with an insulating member, and an electrode pattern connected to the electrode of the electric component is formed thereon, and directly on the insulating layer. It is to be implemented.

That is, the laser driving circuit 100, the polygon motor driving circuit 200, and the synchronization signal processing circuit 30
Numeral 0 is a surface-mount type circuit element, and the circuit element is directly mounted on an electrode pattern formed on an insulating layer on the main substrate 10 by, for example, soldering. Thus, since it is not necessary to separately provide a substrate for forming the circuit, the number of components constituting the laser scanning device 1 can be reduced, and the assembly time can be reduced accordingly. .

The reason why the circuits 100 to 300 are arranged on the periphery of the main body substrate 10 is that the circuits are
This is to keep as far as possible from the optical elements such as the light source unit 20 and the scanning lens 50. By such an arrangement, the adverse effect of the heat generated from the various circuits on the light emitting element and the scanning optical element is reduced as much as possible. be able to.

Reference numeral 80 denotes a connector through which power supply lines and signal lines of the laser drive circuit 100, polygon motor drive circuit 200, and synchronization signal processing circuit 300 are connected to the outside of the laser scanning device 1. It can be connected to a power supply and a control circuit provided. FIG. 2 shows a partial assembly view of the laser scanning device 1.

As shown in FIG. 1, fitting holes 10a to 10f for positioning the cylindrical lens 30 and the scanning lens 50 are formed in the main body substrate 10.
The fitting holes 10a to 10f are formed by pressing or the like.
All the fitting holes are collectively drilled. This is because, rather than individually drilling the fitting holes, it is better to manufacture a precision press die or the like in advance and collectively process the relative positions of the fitting holes with higher accuracy. This is because it can be drilled while maintaining it. Thereby, the cylindrical lens 30 and the scanning lens 50 can be easily and easily attached to accurate positions.

The light source holder 23 of the light source unit 20 is positioned on the main body substrate 10 by a predetermined jig, and is fixed by laser welding. Here, the predetermined jig is provided with fitting holes 10 a to 1 formed in the main body substrate 10.
0f or a polygon motor 41 described later.
It is desirable to use the rotation axis as a reference position. This is because the mounting position of the light source unit 20 is determined by the optical relative positions of the deflecting unit 40 and the scanning lens 50 as described above.

The cylindrical lens 30 is provided with fitting pins 30a, 30b integrally formed on the lower part thereof,
It is attached by fitting it into fitting holes 10e and 10f drilled at 0. Further, similarly to the cylindrical lens 30, the scanning lens 50 is also fitted by fitting the fitting pins 50a to 50d integrally formed at the lower part thereof into fitting holes 10a to 10d formed in the main body substrate 10. .

FIG. 3A is an enlarged view of an attachment portion of the main body substrate 10 to which the scanning lens 50 is attached, and FIG.
FIG. 3C is a diagram illustrating a state after the scanning lens 50 is attached to the main body substrate 10. In addition, FIG.
2 (c), only the main body substrate 10 is shown in a cross-sectional view so that the mounting state can be easily understood. FIG. 3 (a)
As shown in FIG. 1, a fitting pin 50a integrally formed on the lower portion of the scanning lens 50 is fitted into a fitting hole 1 formed in the main body substrate 10.
0a. The method of fixing the scanning lens 50 to the main substrate 10 may be performed via an adhesive S as shown in FIG.
As shown in (c), at the end of the fitting pin 50a,
Caulking may be performed. In the case of caulking as shown in FIG. 3C, it is necessary to make the fitting pin 50a of the scanning lens 50 longer than in the case of FIG. 3B.

The main body substrate 10 of the scanning lens 50
Needless to say, the fixing method is not limited to the above-described method. For example, the upper end of the scanning lens 50 may be fixed by pressing the upper end of the scanning lens 50 toward the main body substrate 10 using a leaf spring or the like. . Referring back to FIG.
Are integrally formed on the main body substrate 10. That is, a hole (not shown) for a rotating shaft is formed in the main body substrate 10 by the above-mentioned press working, and the rotating support shaft is fixed here by laser welding or the like as a positioning hole. On the other hand, a stator coil is provided directly on the surface of the main body substrate 10 by a technique such as patterning around the mounting hole of the rotation spindle, and a polygon mirror 42 integrated with the rotor of the polygon motor 41 is mounted thereon. Attached so that it can rotate with respect to the rotating spindle.

As described above, in the deflecting unit 40, the rotation shaft of the polygon motor 41 is formed integrally with the main body substrate 10, and the deflection unit 40 is formed around the rotation shaft.
The light source unit 2 on the main body substrate 10 is simply assembled.
The optical positional relationship between 0 and the scanning lens 50 can be a predetermined relationship. Further, the reflection mirror 60 and S
The OS sensor 70 is held by the mirror holder 61 and the sensor holder 71 via an adhesive, respectively. The mirror holder 61 and the sensor holder 71 correspond to the light source unit 2.
As in the case of 0, after positioning by a predetermined jig, the periphery thereof is laser-welded and fixed on the main body substrate 10.

(Modification) Although the laser scanning device according to the present invention has been described based on the embodiment, it goes without saying that the content of the present invention is not limited to the above-described embodiment. Such a modification can also be implemented. (1) When affected by vibration due to the rotation of the polygon motor 41 or vibration from a driving device or the like outside the apparatus, the laser beam shakes, which may degrade the drawing accuracy.

As shown in the above embodiment, the main substrate 10
The use of metal for the substrate on which the optical element is mounted makes it possible to increase the natural vibration frequency, and harmful vibration (vibration in the low-frequency range) occurs for the optical element placed there. ). However, in order to further eliminate the influence of vibration, it is desirable that the main body substrate 10 has a vibration damping structure.

For this purpose, a vibration damping steel sheet having a plastic layer as a vibration damping material formed on the surface of a steel sheet may be used as the main body substrate 10. In this case, it is desirable that the plastic layer is formed on the surface opposite to the surface on which the optical element and the like are mounted. This is because, when mounted on a plastic layer, the mounting direction of the optical element and the like may be slightly shifted due to problems such as the accuracy of the thickness of the plastic layer and the smoothness of the surface.

(2) In the above embodiment, no consideration is given to dust. However, the dust adheres to the semiconductor laser or other optical elements, so that the focusing state of the laser beam on the surface to be scanned is deteriorated. For example, a dust-proof cover 90 as shown in FIG. 4 may be placed on the main body substrate 10 as a dust-proof measure.

However, when such a dustproof cover is provided, an opening 90a must be provided on the surface of the dustproof cover 90 on the laser beam emission side so as not to hinder exposure scanning of the surface to be scanned. Further, a transparent glass may be attached to the opening 90a in order to reliably obtain the dustproof effect.

[0032]

As described above, the laser scanning device according to the present invention deflects the laser beam emitted from the light emitting element by the deflecting means, and scans the surface to be scanned via the scanning optical element. Since the light emitting element, the deflecting means, and the scanning optical element are directly mounted on the same surface of the metal flat plate, workability at the time of the mounting is improved, and the assembling efficiency of the laser scanning apparatus is improved. And the manufacturing cost can be reduced. Moreover, precision processing of metal flat plates is possible by pressing, etc.
A positioning hole or the like can be formed with high accuracy. As a result, the precision of the mounting position of the optical component is increased, and since the coefficient of thermal expansion is small due to metal, the positional relationship does not easily fluctuate due to a change in temperature, so that the surface to be scanned can be stably scanned.

Further, the deflecting means comprises a polygon mirror and a motor for driving the polygon mirror, and the motor is integrally formed on the metal flat plate. By simply attaching the light-emitting element, the deflecting means, and the scanning optical element to each other, the optical positional relationship between the light-emitting element, the deflecting means, and the scanning optical element can be accurately set.

Further, there is provided a first drive circuit for driving the light emitting element, and a second drive circuit for driving the deflecting means, wherein at least one of the first and second drive circuits is formed of the flat metal plate. If provided above, the number of parts constituting the laser scanning device is reduced, and the assembly time can be shortened accordingly. The first and / or the second drive circuit provided on the metal flat plate may be disposed on the flat plate peripheral portion remote from the scanning optical element and the light emitting element on the flat plate. The adverse effect of heat generated from the drive circuit on the scanning optical element and the light emitting element can be reduced as much as possible.

Further, since the metal flat plate has a vibration damping structure, it is hardly affected by vibration generated by driving the deflecting means or vibration transmitted from the outside.
Exposure scanning of the scanned surface can be performed stably.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an overall configuration of a laser scanning device 1 according to an embodiment of the present invention.

FIG. 2 is a partial assembly view of the laser scanning device 1 according to the embodiment of the present invention.

FIG. 3A shows a scanning lens 5 on a main body substrate 10;
0 is an enlarged view of a mounting portion, and (b) and (c) are views showing a state after the scanning lens 50 is mounted on the main body substrate 10, respectively.

FIG. 4 is a schematic perspective view of a dust cover 90 according to a modification of the present invention.

[Explanation of symbols]

 Reference Signs List 1 laser scanning device 10 main body substrate 10a to 10f fitting hole 20 light source unit 30 cylindrical lens 30a, 30b fitting pin 41 polygon motor 42 polygon mirror 50 scanning lens 50a to 50d fitting pin 70 SOS sensor 100 laser drive circuit 200 polygon motor Drive circuit 300 Synchronous signal processing circuit

Claims (5)

[The claims] 1. A laser scanning device which deflects a laser beam emitted from a light emitting element by a deflecting means and scans a surface to be scanned through a scanning optical element, wherein the light emitting element is provided on the same surface of a metal flat plate. An element, deflection means,
A laser scanning device, wherein a scanning optical element is directly mounted. 2. The laser scanning device according to claim 1, wherein said deflecting means comprises a polygon mirror and a motor for driving the polygon mirror, and said motor is formed integrally with said metal plate. . A first driving circuit for driving the light-emitting element; and a second driving circuit for driving the deflecting means, wherein at least one of the first and second driving circuits is a metal flat plate. The laser scanning device according to claim 1, wherein the laser scanning device is provided above. 4. The method according to claim 1, wherein the first and / or second driving circuit provided on the metal flat plate is arranged on a peripheral portion of the flat plate, away from the scanning optical element and the light emitting element. The laser scanning device according to claim 3, wherein 5. The laser scanning device according to claim 1, wherein the flat metal plate has a vibration damping structure.