JP2003315710A - Multi-beam scanning device and image forming device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a light source system for combining and emitting light beams from a plurality of semiconductor lasers, a combined light beam is shifted by an optical axis shifting means without requiring a complicated adjustment mechanism. Provided is a multi-beam scanning apparatus and an image forming apparatus that can easily adjust a scanning line pitch. SOLUTION: In a multi-beam scanning apparatus having a plurality of semiconductor laser light sources 11 and 12 and scanning a plurality of light beams, a plurality of light beams are shifted by an optical axis shifting means 100 capable of adjusting an angle at least in a sub-scanning direction. The scanning interval in the sub-scanning direction at the light beam scanning position is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to an optical scanning device used in a writing optical system such as a digital copying machine and a laser printer, and in particular, a multi-beam scanning device in which a recording speed is improved by forming a multi-beam, and The present invention relates to an image forming apparatus.

[0002]

2. Description of the Related Art As a method of increasing the recording speed in an optical scanning device used in a writing optical system such as a digital copying machine and a laser printer, there is a method of increasing the rotation speed of a rotary polygon mirror as a deflecting means. However, in this method, the durability of the motor and the material of the polygonal mirror become problems, and the recording speed is limited. Therefore, in order to reduce the rotation speed of the polygon mirror without decreasing the recording speed, scanning with a plurality of laser beams at one time can be considered. As such a multi-beam scanning device, as disclosed in Japanese Patent Application Laid-Open No. 60-32019, a light source system that combines and emits light beams from a plurality of semiconductor lasers, and Japanese Patent Application Laid-Open No. 2-54211.
As disclosed in the publication, a light source method using a semiconductor laser array in which a plurality of light emitting sources are arranged in an array has been proposed. In the former, the adjustment of the scanning line pitch is performed in the sub-scanning optical axis. The tilt is adjusted by the tilt of the light source around the optical axis in the latter case. Further, the former is characterized in that it can be used in a wide range because the wavelength and output can be selected because a semiconductor laser is used. Further, in order to solve the fluctuation of the beam pitch due to the fluctuation of the environment, there is one disclosed in Japanese Patent Application No. 5-216800. Furthermore, JP-A-9-15994
Japanese Unexamined Patent Publication 7 discloses that a plurality of light sources having different angles in the sub-scanning direction are provided and the light source is selected so as to have a predetermined beam pitch in the sub-scanning direction. Further, Japanese Patent No. 2942721 discloses that light beams from a plurality of light sources are combined via a prism, and the combined light beams are rotated around the optical axis to adjust the beam pitch. Further, Japanese Patent Laid-Open No. 5-208523 discloses rotating a transparent parallel plate in the sub-scanning direction as a light beam irradiation position control means.

[0003]

However, in general, in a multi-beam scanning device, when the light source unit is mounted on the device frame, a predetermined scanning line pitch cannot be obtained due to a mounting error, a processing error of an optical element, etc. There is a problem that is required. The present invention has been made to solve the above-mentioned problems, and in a light source system that combines and emits light beams from a plurality of semiconductor lasers, the combined light is obtained without requiring a complicated adjustment mechanism. It is an object of the present invention to provide a multi-beam scanning device and an image forming apparatus that can easily adjust the scanning line pitch by shifting the beam optical axis.

[0004]

In order to solve the above-mentioned problems, the invention according to claim 1 has at least a multi-beam scanning device having a plurality of semiconductor laser light sources and scanning a plurality of light beams. The most main feature is a multi-beam scanning device configured to control the scanning interval in the sub-scanning direction at the scanning positions of the plurality of light beams by means of optical axis shifting means that allows the angle to be adjusted in the sub-scanning direction. According to a second aspect of the invention, in a multi-beam scanning device having a plurality of semiconductor laser light sources and scanning a plurality of light beams, the other light beams are angled at least in the sub-scanning direction with respect to the reference light beam. The most main feature is a multi-beam scanning device configured to control the scanning interval in the sub-scanning direction at the scanning positions of the plurality of light beams by means of an optical axis shifting means that makes it adjustable. According to a third aspect of the invention, there is provided a multi-beam scanning device having a plurality of semiconductor laser light sources and a means for synthesizing beams emitted from the semiconductor laser light sources, and scanning a plurality of light beams,
The main feature of the multi-beam scanning device is configured to control the scanning interval in the sub-scanning direction at the scanning position of the plurality of light beams by means of optical axis shifting means that makes the angle adjustable at least in the sub-scanning direction. . According to a fourth aspect of the invention, in a multi-beam scanning device having a plurality of semiconductor laser light sources and a means for combining beams emitted from the semiconductor laser light sources, a reference light beam is provided in a multi-beam scanning device for scanning a plurality of light beams. On the other hand, a multi-beam configured to control the scanning interval in the sub-scanning direction at the scanning position of the plurality of light beams by means of optical axis shifting means for adjusting the angle of the other light beams at least in the sub-scanning direction The scanning device is the most important feature.

According to a fifth aspect of the invention, the semiconductor laser light source is mainly characterized in that it comprises an LD having a single light emitting point or an LD array having a plurality of light emitting points. According to a sixth aspect of the invention, the optical axis shift means is a vari-angle prism, and the main feature is the multi-beam scanning device according to any one of the first to fifth aspects. In the invention according to claim 7, the multi-beam scanning device according to claim 6, wherein the optical axis of the incoming and outgoing light of the vari-angle prism, which is the optical axis shifting means, does not coincide with the normal line of each surface of the vari-angle prism. Is the main feature. The invention according to claim 8 is characterized mainly in the multi-beam scanning device according to any one of claims 1 to 5, wherein the optical axis shifting means is a vari-angle mirror. In the invention according to claim 9, the means for synthesizing the beams emitted from the plurality of light sources is a prism, and the optical axis shifting means is provided between the prism and the light source. The main feature is the scanning device. According to the invention of claim 10,
8. A coupling lens for coupling divergent light fluxes from the plurality of light sources, and the optical axis shifting means after the coupling lens.
The multi-beam scanning device according to any one of 8 and 9 is a main feature. In the invention described in claim 11, claims 1 to 10
An image forming apparatus using any one of the above multi-beam scanning devices is a main feature.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. 1 shows a multi-beam scanning device as an example of an embodiment of the present invention.
At, the laser light from the semiconductor laser light source 12 is
The polygon mirror 31 passes through the coupling lens 17 and a variable angle prism (optical axis shifting means) 100 that shifts the optical axis by varying the apex angle in at least the sub-scanning direction, and transmits the cylindrical lens 30.
Incident on. Further, the laser light from the semiconductor laser light source 11 passes through the cylindrical lens 30 via the coupling lens 16 and enters the polygon mirror 31. Here, on the reflecting surface of the polygon mirror 31, the laser light from the light source 12 and the laser light from the light source 11 have an angle in the main scanning direction and an angle in the sub scanning direction. In this case, the reference light is the laser light from the light source 11. The vari-angle prism 100 has mutually parallel planes of entrance and exit. When the vari-angle prism 100 is perpendicular to the optical axis, the reflected light returns to the light source and enters the PD for detecting the amount of light, which adversely affects the output control of the LD. It is arranged so that the optical axis of the laser beam and the normal line of each surface do not coincide with each other so as to prevent the influence. This allows
Since the composite optical system of a plurality of beams is not used, the number of parts is small and the beam pitch on the scanning surface can be controlled. Since the reference light of the plurality of beams is provided, the optical axis of the other beam can be shifted. Furthermore, since a vari-angle prism used for preventing camera shake of a video camera or the like is provided, the optical axis can be easily adjusted. Furthermore, it is possible to prevent the generation of ghost light due to the reflected light and reduce the adverse effects on the light source output control and the like. Moreover, since the vari-angle mirror is used, a layout with a high degree of freedom can be realized. The semiconductor laser light source may be composed of an LD having a single light emitting point, or an L having a plurality of light emitting points.
You may comprise from a D array.

FIG. 2 is a schematic diagram of the optical axis shift of the vari-angle prism 100. In FIG. 2, θ indicates the apex angle of the vari-angle prism 100. Here, the light source 12
May be an LD array having a plurality of light emitting points. Figure 3
Shows an example using a vari-angle mirror (optical axis shifting means) 101 and a prism 102 in the embodiment of the present invention. The vari-angle mirror 101 shifts the optical axis at least in the sub-scanning direction, and A prism 102 such as a PBS (Polarization Beam Splitter) combines the traveling directions of the light speeds of the laser lights, passes through the cylindrical lens 30, and then enters the polygon mirror 31.
Here, the direction of the laser light at the angle 2β changes by tilting by β in the sub-scanning direction with the main scanning direction as the rotation axis, and in this case, the reference light is the laser light from the light source 11. In the figure, the same symbols as those in FIG. 1 are the same. This makes it possible to increase the degree of freedom in the optical layout by using the multiple beam combining optical system. Also, the optical axis of the other beam can be shifted. Further, since the optical axis shift means is provided between the prism and the light source device, the beam pitch can be effectively corrected. 4 is a schematic view showing the image forming apparatus,
In FIG. 4, the beam pitch is detected by the fat sensor 102a before scanning the photoconductor 101a, and the calculation unit 103
The semiconductor laser drive unit 36a that controls the writing start timing and light emission of the semiconductor laser, and the vari-angle prism 100 or the vari-angle mirror 101 in the light source unit 105 by the drive control unit 104 of the optical axis shifting means.
Control the angle of the laser light freely,
Adjust the beam pitch on the photoconductor. As a result, the beam pitch is optimized and a good image is obtained. In the figure, 31 is a polygon mirror, and 32 and 33 are scanning lenses of a scanning optical system. Therefore, an image forming apparatus is realized by combining these light source devices with an electrophotographic process. FIG. 5 shows an example in which the vari-angle prism 100 and the prism 21 are combined in the embodiment of the present invention.
In the figure, the same symbols as those in FIG. 1 are the same. Figure 6
An example of a vari-angle mirror is shown. The vari-angle mirror uses piezoelectric elements 101a, 1
01b is deformed, and the mirror 101 is inclined by β and the laser beam changes its direction by an angle of 2β.

[0008]

As described above, according to the first aspect of the present invention, since the multiple beam combining optical system is not used, the number of parts is small and the beam pitch on the scanning surface can be controlled. According to the second aspect, since the reference light of the plurality of beams is provided, the optical axis of the other beam can be shifted. Also, a plurality of optical axis shifting means may be provided, but the number of parts can be reduced here. According to the third aspect, it is possible to increase the degree of freedom of the optical layout by using the multiple beam combining optical system. Both prism and mirror methods can be used. According to the fourth aspect, like the second aspect, the optical axis of the other beam can be shifted. A plurality of optical axis shifting means may be provided, but the number of parts can be reduced here. According to the fifth aspect, since the semiconductor laser light source can be appropriately configured, the number of parts can be surely reduced and the optical axis can be adjusted more easily. According to the sixth aspect, since the vari-angle prism used for preventing camera shake of a video camera is provided,
The optical axis can be easily adjusted. According to the seventh aspect, it is possible to prevent generation of ghost light due to reflected light, and reduce adverse effects on light source output control and the like. According to the eighth aspect, since the vari-angle mirror is used, a layout with a high degree of freedom is possible. According to the ninth aspect, since the optical axis shifting means is provided between the prism and the light source device, the beam pitch can be effectively corrected. Claim 10
According to this, since the optical axis shifting means is provided after the coupling lens is emitted, it is possible to absorb the coupling lens assembling error and the like. According to the eleventh aspect, it is possible to form a good image having a uniform beam pitch.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of an embodiment of the present invention.

FIG. 2 is a schematic diagram of shifting the optical axis of a vari-angle prism.

FIG. 3 is a schematic diagram showing an example using a variangle mirror and a prism in the embodiment of the present invention.

FIG. 4 is a schematic diagram showing an image forming apparatus.

FIG. 5 is a schematic view showing an example in which a vari-angle prism and a prism are combined in the embodiment of the present invention.

FIG. 6 is a schematic view showing an example of a vari-angle mirror.

[Explanation of symbols]

11 light sources, 12 light sources, 16 coupling lenses,
17 coupling lens, 21 prism, 100
Vari-angle prism (optical axis shifting means), 101 Vari-angle mirror (optical axis shifting means)

Claims (11)

[Claims] 1. A multi-beam scanning device having a plurality of semiconductor laser light sources and scanning a plurality of light beams,
A multi-beam scanning device, characterized in that it is configured to control a scanning interval in the sub-scanning direction at a scanning position of the plurality of light beams by means of an optical axis shifting means that can adjust an angle at least in the sub-scanning direction. 2. A multi-beam scanning device having a plurality of semiconductor laser light sources and scanning a plurality of light beams,
An optical axis shift means for adjusting the angle of at least the other light beams with respect to the reference light beam in the sub-scanning direction is used to control the sub-scanning direction scanning interval at the scanning position of the plurality of light beams. A multi-beam scanning device characterized by being configured. 3. A plurality of semiconductor laser light sources, and means for synthesizing beams emitted from the semiconductor laser light sources,
In a multi-beam scanning device that scans a plurality of light beams, at least a scanning interval of the plurality of light beams in a sub-scanning direction is controlled by an optical axis shift means that is adjustable in angle in the sub-scanning direction. A multi-beam scanning device having the above structure. 4. A plurality of semiconductor laser light sources, and means for synthesizing beams emitted from the semiconductor laser light sources,
In a multi-beam scanning device that scans a plurality of light beams, the plurality of light beams are moved by an optical axis shifting means that makes it possible to adjust the angle of at least the other light beams with respect to the reference light beam in at least the sub-scanning direction. A multi-beam scanning device characterized in that it is configured to control a scanning interval in the sub-scanning direction at the scanning position. 5. The multi-beam scanning device according to claim 1, wherein the semiconductor laser light source is an LD having a single light emitting point or an LD array having a plurality of light emitting points. apparatus. 6. The multi-beam scanning device according to claim 1, wherein the optical axis shifting means is a vari-angle prism. 7. The multi-beam according to claim 6, wherein the optical axis of the incoming and outgoing light of the vari-angle prism, which is the optical axis shifting means, does not coincide with the normal line of each surface of the vari-angle prism. Scanning device. 8. The multi-beam scanning device according to claim 1, wherein the optical axis shift means is a vari-angle mirror. 9. A prism for synthesizing the beams emitted from the plurality of light sources, and the optical axis shifting device between the prism and the light source.
9. The multi-beam scanning device according to any one of 8 above. 10. A coupling lens for coupling divergent light beams from the plurality of light sources, and the optical axis shifting means after the coupling lens. The multi-beam scanning device according to any one of 7, 7, 8 and 9. 11. An image forming apparatus using the multi-beam scanning device according to claim 1.