JP2001066533A - Laser scanning optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser scanning optical device capable of securing a good-quality image by stably generating a laser beam and making beam shape stable. SOLUTION: This device is equipped with a laser diode 1 generating the laser beam L, a collimating lens part 2 making the laser beam L parallel laser beams L, a 1st aperture part 6 having a through-hole deciding the shape of the parallel laser beams L, and a laser beam scanning means 7 performing scanning with the laser beam L sent from the aperture part 6. A converging lens part 3 converging the parallel laser beams L, a 2nd aperture part 4 having a complete circular through-hole having a diameter nearly equivalent to the diameter of the converged laser beam, and a collimator lens part 5 making the converged laser beam the parallel laser beams are disposed between the lens part 2 and the aperture part 6. The aperture part 4 is arranged so that the focal position of the laser beam L converged by the lens part 3 is aligned with the center of the through-hole of the aperture part 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser scanning optical device, and more particularly to a laser printer, a laser facsimile,
The present invention relates to a laser scanning optical device used for a copying machine or the like.

[0002]

2. Description of the Related Art A conventional laser scanning optical device is shown in FIGS. 5 and 6, a laser scanning optical device includes a laser diode 101, a laser-side optical system 113 on a laser emitting side, and a laser beam L transmitted from the laser-side optical system 113 converted into a scanning laser beam L. And a photosensitive drum side optical system 114 that irradiates the photosensitive drum 112 with the scanning laser beam L sent from the polygon mirror 108. Here, the laser-side optical system 113 includes the collimator lens 102, the aperture 106, and the cylinder lens 107, and the photosensitive drum-side optical system 114 includes the Fθ lens 1
10, 111 are provided. The polygon mirror 108 is driven to rotate by a polygon motor 109.

[0003] The laser beam L generated by the laser diode 101 is formed into an appropriate light beam via a collimating lens 102 and an aperture 106, and is sent to a cylinder lens 107. Next, the laser light L
Are converged linearly by the cylinder lens 107 and are irradiated to the polygon mirror 108. Here, this laser light L
Is scanned in the main scanning direction by being reflected by a polygon mirror 108 rotated and driven by a polygon motor 109. Next, the scanned laser light L is condensed by the Fθ lenses 110 and 111 so as to be focused on the photosensitive drum 112, and is irradiated onto the charged photosensitive drum 112. Thus, an image pattern of an electrostatic latent image is formed on the photosensitive drum 112. Then, charged toner is applied to the electrostatic latent image on the photosensitive drum 112 described above, and the visible image formed by this is transferred to recording paper.

Here, the light trace of the laser light L from the laser diode 101 to the cylinder lens 107 will be described with reference to FIG. The laser light L generated by the laser diode 101 is converted into a parallel light by the collimating lens 102. Next, the laser beam L, which has become a parallel light beam, is shaped into an appropriate beam diameter by passing through the aperture 106, and is then transmitted to the cylinder lens 107.

[0005]

In the conventional laser scanning optical apparatus constructed as described above, a part of the laser beam L is cut off and reflected by the aperture 106 which is shaped into an appropriate beam diameter. I do. Then, the reflected laser light La returns to the laser diode 101 and may enter. In this case, the incident reflected laser light La acts on the laser diode 101 as return induced noise, and the generation of the laser light L may become unstable. When this is used in a printer or the like, There has been a problem that printing is adversely affected.

Further, the laser diode 101 may enter a multi-mode transmission state due to the influence of changes in temperature and humidity conditions. In this case, the beam shape of the laser beam L generated from the laser diode 101 becomes unstable, and
As described above, side peaks occur, which adversely affects printing.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a laser scanning optical device which can solve the above-mentioned disadvantages of the prior art, and in particular, can stabilize the generation of a laser beam and a beam shape and can secure a high quality image. Is its purpose.

[0008]

To achieve the above object, according to the first aspect of the present invention, there is provided a laser diode for generating a laser beam, a collimating lens unit for converting the laser beam into a parallel laser beam, A first aperture having a through hole for determining the shape of the parallel laser light; and a laser light scanning means for scanning the laser light emitted from the first aperture. Further, a converging lens portion for converging the parallel laser light and a perfect circular through hole having a diameter substantially equal to the diameter of the converged laser light are provided between the collimating lens portion and the first aperture portion. And a parallel lens unit for converting the converged laser light into parallel laser light. Further, the above-described second aperture section is arranged such that the focal position of the laser beam converged by the converging lens section and the center of the through hole of the second aperture section coincide. With this configuration, a part of the laser light reflected by being shaped in the first aperture portion described above is not a uniform mirror surface because the surface shape of the first aperture portion is not uniform. It does not reflect. Therefore, most of the irradiation positions of the reflected laser light at the position of the second aperture part are shifted from the positions of the through holes. As a result, most of the reflected laser light is cut off at the second aperture section, and the reflected laser light reaching the laser diode is
Significantly reduced. Further, the converged laser light passes through the through-hole of the second aperture part,
Even when the shape of the laser light emitted from the laser diode is disturbed, the beam shape of the laser light can be adjusted, and the occurrence of side peaks can be suppressed.

According to a second aspect of the present invention, in the first aspect of the present invention, a reflection / diffusion member for irregularly reflecting the laser light is provided on the surface of the first aperture portion where the laser light is incident. With this configuration, in addition to having the function equivalent to that of the first aspect of the present invention, a part of the laser light reflected by being shaped by the first aperture portion is surely irregularly reflected. Will be
Therefore, more reflected laser light is blocked by being displaced from the position of the through hole in the second aperture portion,
As a result, the reflected laser light reaching the laser diode is further greatly reduced.

According to a third aspect of the present invention, in the second aspect of the present invention, instead of the reflection / diffusion member,
The surface of the first aperture portion on the side where the laser light was incident was a reflection / diffusion surface subjected to reflection / diffusion processing for irregularly reflecting the laser light. With this configuration, in addition to having the same function as the above-described second aspect of the present invention, there is no need to prepare a member as a separate part, so that the size can be reduced and the cost can be reliably reduced. it can.

According to a fourth aspect of the present invention, in the first aspect of the present invention, a reflection-absorbing member for suppressing the reflection of the laser light is provided on the surface of the first aperture portion where the laser light is incident. With this configuration, in addition to having the same function as the above-described invention of claim 1, furthermore,
The portion of the laser beam restricted for shaping in the first aperture portion is substantially absorbed, so that the laser beam reflected in the direction of the laser diode in the first aperture portion is greatly reduced.

According to a fifth aspect of the present invention, in the first aspect of the present invention, an annular and mountain-shaped projection is formed around the through hole in the surface of the first aperture portion on the side where the laser beam is incident. Was installed. With this configuration, in addition to having the same function as the above-described first aspect of the present invention, the reflection direction of a part of the laser light reflected for shaping in the first aperture portion is changed to the central axis. The reflected laser light reaching the laser diode is almost surely reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIG. Here, FIG. 1 shows a first embodiment of the present invention.
It is a schematic explanatory view of the laser scanning optical device showing the embodiment. The laser scanning optical device shown in FIG. 1 has a collimating lens unit 2 having a function of deflecting a laser beam L output from a laser diode 1 into a parallel laser beam L, and a laser beam L for shaping the laser beam L into an appropriate shape. And a laser beam scanning means 7 for scanning the laser beam L. Further, the laser scanning optical device includes a converging lens unit 3 having a function of converging a parallel laser beam L between the collimating lens unit 2 and the first aperture unit 6; The second aperture portion 4 having a perfect circular through hole having a diameter substantially equal to the diameter of the laser beam L at the focal position of L, and the laser beam L that is converged and then diffused is converted into a parallel laser beam L And a parallel lens unit 5 having a function of deflecting light. Here, the center position of the through hole of the second aperture section 4 is set so as to coincide with the focal position of the laser beam L converged by the converging lens section 3. Then, the center position of each member described above is arranged so as to coincide with the center of the optical axis of the laser beam L.

Next, the operation and effect of the above-described embodiment will be described. The laser light L generated by the laser diode 1 becomes parallel laser light L by the collimating lens unit 2 disposed next. Subsequently, the parallel laser light L is sent to the converging lens unit 3, is converged by the converging lens unit 3, and focuses on a predetermined position. Here, the second aperture part 4 is installed so that the center of the through hole coincides with the focal position of the laser beam L,
The converged laser light L passes through the through hole. Subsequently, after focusing, the laser light L spreading
Is deflected again by the parallel lens section 5 to be parallel laser light L, and is sent out to the first aperture section 6. Here, the laser beam L is shaped into an appropriate beam diameter by passing through the through hole of the first aperture section 6. Next, the first aperture unit 6 described above is used.
The laser light L sent out is optically scanned by the laser light scanning means 7. Here, the specific configuration and operation after the laser beam scanning means 7 are the same as those described in the above-described conventional technique.

Here, a part of the laser light L reflected by being shaped in the first aperture section 6 is reflected.
a returns to the laser diode 1 direction. In this case, the reflected laser beam La does not have a uniform specular reflection because the surface shape of the first aperture section 6 is not a uniform mirror surface, and the direction of the reflection slightly changes. Therefore,
Even in the case where the reflected laser beam La reaches the second aperture unit 4 via the parallel lens unit 5,
At the position of the second aperture part 4, the irradiation position of many reflected laser beams La does not become the same as the position of the through hole. As a result, most of the reflected laser light La
Is blocked at the aperture section 4. Therefore, the laser beam La reflected by the first aperture unit 6 is
The amount of light reaching the laser diode 1 is greatly reduced. As a result, the operating characteristics of the laser diode 1 can always be kept normal, and the generation of the laser beam L can be stabilized, and printing disturbance can be prevented when using a printer or the like, and a high-quality image can be secured. It becomes possible.

Further, even when the beam shape of the laser light L emitted from the laser diode 1 is disturbed, the converged laser light L is transmitted to the second aperture section 4 by the converged laser light L. By passing through a perfectly circular through hole having a diameter substantially equal to the diameter of the laser beam L, a portion where the beam shape of the laser beam L is disordered is cut off. This allows
The beam shape of the laser beam L can be adjusted, the occurrence of side peaks can be suppressed, and a high-quality laser beam can be always maintained, and a high-quality image can be secured in the same manner as described above.

Hereinafter, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the surface of the first aperture section 6 on the side where the laser beam L is incident is provided with a reflection / diffusion member 6 made of a material that irregularly reflects the reflection of the laser beam L.
a is installed. As a result, the first aperture section 6
Is reflected irregularly in the laser beam L. Therefore, even when the reflected laser light La reaches the second aperture part 4 via the parallel lens part 5, more reflected laser light La is irradiated at the position of the second aperture part 4. The position is shifted from the position of the through hole. Therefore, the reflected laser light La is more blocked in the second aperture unit 4, so that the reflected laser light La from the first aperture unit 6 is
The amount of light reaching the laser diode 1 can be further reduced.

Although not shown, the laser beam L of the first aperture section 6 is used instead of the above-mentioned reflection / diffusion member 6a.
May be a reflection / diffusion surface subjected to reflection / diffusion processing for irregularly reflecting the laser beam L. As a result, the same effects as those described above can be obtained, and further, there is no need to prepare a member as a separate component, so that downsizing can be achieved and cost reduction can be reliably realized.

Next, a third embodiment of the present invention will be described with reference to FIG. In this embodiment, a reflection absorbing member 6b for suppressing the reflection of the laser light L is provided on the surface of the first aperture section 6 on the side where the laser light L is incident. Here, the reflection absorbing member 6b may be made of any material that can easily absorb the laser light L. As a result, the portion of the laser beam L restricted for shaping in the first aperture section 6 is:
It will be almost absorbed. Therefore, in the first aperture section 6, the amount of the laser light L reflected in the direction of the laser diode 1 can be significantly reduced, the operating characteristics of the laser diode 1 are always kept normal, and the generation of the laser light L is performed. Contributes to stabilization.

Next, a fourth embodiment of the present invention will be described with reference to FIG. In this embodiment, a protruding portion 6c is provided around the through-hole on the surface of the first aperture portion 6 on the side where the laser light L is incident, the protruding portion 6c having a mountain-shaped protuberance having a vertex on the central axis side. ing. As a result, the reflection direction of the laser beam L at the first aperture section 6 is directed outward from the central axis. Therefore, at the position of the second aperture part 4, the irradiation position of the reflected laser light La is almost certainly shifted from the position of the through hole. Therefore, the laser light La reflected by the first aperture unit 6 is:
Reaching to the laser diode 1 can be almost certainly reduced, thus contributing to always keeping the operating characteristics of the laser diode 1 normal and stabilizing the generation of the laser light L.

Although not shown, the material of the projection 6c may be formed of the above-mentioned reflection / absorption member 6b. Accordingly, the above-described operation and effect can be obtained, and the amount of the reflected laser light La can be further reduced, so that the reflected laser light La can be more reliably prevented from reaching the laser diode 1. .

[0022]

As described above, according to the first aspect of the present invention, the laser beam converged and focused at the converging lens unit is passed through the through-hole of the second aperture unit disposed at the focal position. , And thereafter, the laser beam is shaped so as to have an appropriate beam diameter in the first aperture section, so that most of the laser light reflected by the shaping in the first aperture section is converted into the second aperture. It is cut off by being displaced from the position of the through hole of the portion, and greatly reduces reaching to the laser diode. As a result, the operating characteristics of the laser diode can be kept normal, and the generation of laser light can be stabilized.

Further, as described above, since the converged and focused laser beam passes through the through hole of the second aperture section, the shape of the laser beam generated from the laser diode is disturbed. Even in the case where it occurs, the beam shape of the laser light after the second aperture portion can be adjusted, and the occurrence of side peaks can be suppressed.
It is possible to always keep a good quality laser beam shape.

According to the second aspect of the present invention, in addition to having the above-described functions and effects of the first aspect, a reflection / diffusion member for irregularly reflecting the laser light is provided in the first aperture portion. Is irregularly reflected, so that the reflected laser light is more reliably deviated from the position of the through-hole of the second aperture portion and is blocked, so that reaching the laser diode can be further greatly reduced. Thereby, generation of laser light can be further stabilized.

According to the third aspect of the present invention, in addition to having the above-described effects of the second aspect, there is no need to prepare a member as a separate part, and it is possible to reduce the size. Thus, cost reduction can be reliably realized.

According to the fourth aspect of the invention, in addition to having the above-described effects of the first aspect, a reflection / absorption member for suppressing reflection of laser light is provided in the first aperture portion. The reflection of laser light is suppressed, and therefore, the amount of laser light reflected in the direction of the laser diode can be significantly reduced. Thereby, generation of laser light can be further stabilized.

According to the fifth aspect of the present invention, in addition to having the above-described effects of the first aspect, an annular and mountain-shaped projection is provided around the through hole of the first aperture portion. Therefore, the direction of reflection of the laser light is directed outward, so that the incidence of the laser light on the laser diode can be reliably reduced. This makes it possible to more reliably stabilize the generation of laser light.

Since the present invention is constructed and functions as described above, a laser capable of stabilizing the generation of a laser beam and the beam shape thereof, preventing the printing from being disturbed when using a printer or the like, and ensuring a high quality image. A scanning optical device can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a laser scanning optical device according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a reflection / diffusion member attached to a first aperture unit according to a second embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view showing a reflection-absorption member attached to a first aperture unit according to a third embodiment of the present invention.

FIG. 4 is a schematic sectional view showing a projection attached to a first aperture according to a fourth embodiment of the present invention.

FIG. 5 is a schematic explanatory view showing a conventional laser scanning optical device.

FIG. 6 is a schematic explanatory view showing a portion from a laser diode to a cylinder lens in FIG. 5;

[Explanation of symbols]

 L laser beam 1 laser diode 2 collimating lens unit 3 converging lens unit 4 second aperture unit 5 parallel lens unit 6 first aperture unit 6a reflection / diffusion member 6b reflection / absorption member 6c projection unit 7 laser beam scanning means

Claims (5)

[Claims] A laser diode for generating a laser beam; a collimating lens unit for converting the laser beam into a parallel laser beam; a first aperture unit having a through-hole for determining a shape of the parallel laser beam; A laser scanning optical device including a laser beam scanning unit that scans a laser beam transmitted from a first aperture unit, wherein the parallel laser beam is converged between the collimating lens unit and the first aperture unit. A converging lens portion, a second aperture portion having a perfect circular through hole having a diameter substantially equal to the diameter of the converged laser light, and a parallel lens portion for converting the converged laser light into parallel laser light Are sequentially arranged, and the second aperture section is arranged such that the focal position of the laser beam converged by the converging lens section and the center of the through hole of the second aperture section coincide with each other. Laser scanning device, characterized in that. 2. The laser scanning optical device according to claim 1, wherein a reflection diffusion member for irregularly reflecting the laser light is provided on a surface of the first aperture portion on a side where the laser light is incident. 3. The method according to claim 1, wherein the reflection-diffusion member is replaced by a reflection-diffusion surface subjected to reflection-diffusion processing for irregularly reflecting the laser light. The laser scanning optical device according to claim 2. 4. The laser scanning optical device according to claim 1, wherein a reflection-absorbing member for suppressing reflection of the laser light is provided on a surface of the first aperture portion on a side where the laser light is incident. 5. The laser scanning device according to claim 1, wherein an annular and mountain-shaped projection is provided around a through hole in a surface of the first aperture portion on a side where the laser beam is incident. Optical device.