JPH04226414A - Optical scanner - Google Patents

Abstract

PURPOSE:To provide the optical scanner which is simplified in constitution. CONSTITUTION:This device has a light source 1 which oscillates rays, a lens 2 which converges these rays and a reflection mirror 9 which has an inclination with the rays 12 transmitted through the above-mentioned lens 2 and has one reflection surface 10 to reflect the rays transmitted through this lens 2. The rays are reflected by this reflection mirror 9 and the reflection mirror 9 is rotated around the center 17 of the rays after the transmission through the lens as the axis of rotation by a rotating means, by which scanning is executed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device for recording characters, figures, etc. by irradiating a photoreceptor with a light beam.

0002

2. Description of the Related Art In recent years, optical scanning devices using laser beams have been increasingly used as a method for recording characters, figures, etc.

A conventional optical scanning device using this laser beam will be explained below with reference to the drawings.

FIG. 9 is a schematic perspective view of a conventional optical scanning device. Further, FIG. 10 is an optical path diagram focusing only on the convergence of the optical path of the light ray. As shown in FIGS. 9 and 10, the constituent elements 1 are a light source that oscillates a laser beam 12, 2 is a collimating lens that corrects the laser beam 12 into a parallel beam, and 3
4 is a modulator that makes the aperture of the laser beam 12 a perfect circle; 4 is a cylinder lens that corrects the traveling direction of the laser beam 12;
5 is a rotating polygon mirror that reflects the laser beam 12; 6 is an fθ lens that corrects distortion of the laser beams 13-1 to 13-n reflected by the rotating polygon mirror 5; and 7 is a lens that is caused by the tilt of the surface of the rotating polygon mirror 5. A cylindrical lens 8 is a photoreceptor that corrects vertical blurring of the laser beams 13-1 to 13-n. A photosensor 20 receives the laser beam 13-1 and synchronizes the positions of the rotating polygon mirror 5 and the photoreceptor 8.

Next, the relative operations of the above-mentioned components will be explained. Laser light emitted from a light source 1 passes through a collimator lens 2, a modulator 3, and a cylinder lens 4, and reaches a rotating polygon mirror 5. The light is reflected by the rotating polygon mirror 5, passes through the fθ lens 6 and the cylinder lens 7, and is irradiated onto the photoreceptor drum 8. How the laser beam 9 is scanned on the photoreceptor 8 at this time will be briefly explained using FIG. 8.

As shown in the figure, a laser beam 12 incident on the rotating polygon mirror 5 is reflected and becomes reflected light 13-1. Then, as the rotating polygon mirror 5 rotates, the reflected light 13-2
, the reflected light 13-3 and the reflected direction change to scan the photoreceptor 8.

[0007]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional apparatus, each surface of the rotating polygon mirror 5 must be processed to have a uniform position, angle, and surface finish from the center of rotation on each surface with high precision. However, the manufacturing process requires a considerable amount of time. Furthermore, since the rotating polygon mirror 5 has a considerable size, the fθ lens 6 must also be large accordingly. Furthermore, since the light incident on the fθ lens 6 is not normally focused on the photoconductor 8 as it is, the fθ lens 6 needs to have a characteristic that converges the light beam onto the photoconductor 8 to a required minute diameter in addition to the fθ characteristic. becomes. For this,
The degree of freedom in designing the fθ lens 6 is reduced.

In addition, since the rotating polygon mirror 5 has a bevel on each of its reflecting surfaces, cylinder lenses 4 and 7 must be provided to correct vertical blurring of the laser beam 12. If the fθ lens 6 is included, the device will become larger. Further, the reflection position of the light on the rotating polygon mirror 5 moves with rotation and is not constant, and as shown in FIG. 11, the reflection positions between the reflected light 13-1 and the reflected light 13-3 are shifted by ΔL. For this reason, an optical path difference occurs in the reflected light, resulting in poor printing accuracy.

[0009] As described above, conventional optical scanning devices have had the above-mentioned problems. The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide an optical scanning device that is small and lightweight due to its simple configuration, and has high printing accuracy.

0010

[Means for Solving the Problems] In order to achieve the above object, the optical scanning device of the present invention is an optical scanning device using a light beam such as a laser beam. It consists of a single reflecting surface that rotates around the center of the incident light, and an optical system lens that converges the incident light is provided on the incident light side of this reflecting mirror, and by rotating the reflecting mirror, the surface of the photoreceptor is scanned. be.

[0011]

[Operation] The reflecting mirror of the optical scanning device of the present invention having the above configuration has only one reflecting surface and is inclined with respect to the optical axis of the light beam,
Even if the reflecting mirror rotates in order to reflect the center of the light beam on the center of the rotation axis, the reflection position of the reflected light beam is always unchanged, so that no optical difference occurs. Therefore, convergence is performed only by the optical system lens on the incident light side of the reflecting mirror, and scanning can be performed with a reliably converged image. Furthermore, since it is a single surface, there is no scanning blur due to each reflective surface that occurs with a polygon mirror, and a lens for correcting the blur is not required, resulting in a simple configuration.

0012

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 are diagrams showing embodiments of the present invention, respectively. FIG. 1 is a schematic perspective view of an optical scanning device according to an embodiment of the present invention, and FIG. 2 focuses only on the convergence of the optical path of the light beam. This is an optical diagram.

Note that in FIG. 1, the same components as in the conventional example are given the same reference numerals as in FIG. 9, and a description thereof will be omitted. As shown in FIG. 1, 9 is a reflecting mirror that reflects the laser beam 12, and 10 is a reflecting surface of the reflecting mirror 9. As shown in FIG.

Next, the constituent elements and their related operations will be explained below. First, a laser beam 12 emitted from a light source 1 is converged by a lens 2 into a light beam, and a modulator 3 corrects the aperture to a perfect circle. Next, the laser beam 12 is incident on the reflective surface 10 of the reflective mirror 9 . Now, the reflecting mirror 9 rotates about its rotation axis 17 or vibrates alternately clockwise and counterclockwise. Therefore, the laser beam 12 incident on the reflective surface 10 is swung horizontally and scans the photoreceptor 8.

Further, as shown in FIG. 3, since the reflected light 13 is reflected from the reflecting surface 10 of the single-sided reflecting mirror 9, there is no need for surface tilt correction, and therefore a cylinder lens is not required. Further, the optical system lens of the lens 2 forms an image of the light beam onto the photoreceptor 8.

From the above, the lens configuration consists of only the converging lens 2, as shown in the converging configuration of light rays in FIG. Therefore, the configuration can be significantly simplified.

FIG. 4 is an explanatory diagram of the scanning angle of the optical scanning device of the present invention, and FIG. 5 is an explanatory diagram of the scanning angle of the conventional case for comparison. In FIG. 4a, the incident laser beam 12 is Reflected laser beam 13 by reflector 9
-1.

FIG. 4b shows that the reflecting mirror 9 is rotated by an angle θ, and in this case the reflected laser beam (13-
2) is scanned by an angle θ from the reflected laser beam 13-1 in FIG. 4a. On the other hand, in the conventional device shown in FIG. 5, when the rotating polygon mirror 5 rotates by θ, the reflected laser beam 13-2
The difference is that the reflected laser beam 13-1 is scanned by an angle of 2θ, and the scanning angle relative to the rotation angle of the reflecting mirror is smaller than that of the conventional method, but the reflection point remains unchanged and distortion due to the optical path difference is small. In addition, the rotation angle can be adjusted because the configuration of the reflector is simple.
You can increase the rotation speed.

Next, other embodiments will be explained. FIG. 6 is a side sectional view of the optical scanning device.

In this embodiment, mirrors 71a, 71b, 7
1c, a light source unit 72, etc., which are disposed within a chassis 73. The chassis 73 is made of, for example, resin. FIG. 7 shows a perspective view of the optical scanning device from the back side. Mirrors 71a, 71b, and 71c are fixed at predetermined positions on the chassis 73, and these fixed portions are formed in consideration of the direction in which light is reflected by the mirrors 71a, 71b, and 71c. Mirrors 71a, 71b, 7
1c extends across the width direction of the chassis 73 (direction of arrow W in FIG. 7) and reflects the laser beam from the mirror unit 85 toward the photoreceptor 8. Further, a mounting portion 75 for fixing the entire optical scanning device to the image recording device is provided at a predetermined position of the chassis 73. On the other hand, the chassis 73 is provided with an opening 76 . The opening 76 has a rectangular shape, and is disposed at a position that faces the mirror 71c and allows the reflected light from the mirror 71c to pass through.

Here, the mirrors 71a, 71b, 71c are housed within the chassis 73, and the mirrors 71a, 71b, 71c are
Since the opening 76 of No. 3 also has only the size and shape necessary for passing the reflected light from the mirror 71c, the amount of dust entering into the chassis 73 is extremely small.

As shown in FIG. 6, the light source unit 72 includes a light source 1, a collimator lens 2, and a chassis 73, which are integrally provided on the chassis 73. For example, a semiconductor laser is used as the light source 1.
The laser light from the mirror unit 85 enters the mirror unit 85 via the collimator lens 2.

The mirror unit 85 is composed of a 45° mirror 9 and a drive motor 88, and the laser beam from the light source 81 is incident on the rotation axis of the 45° mirror 9 and is reflected in the right angle direction. The 45° mirror 9 is driven by a drive motor 88
rotates at a predetermined speed. Thereby, the laser beam from the light source 1 is scanned in the horizontal direction with the 45° mirror 9 as the center.

Furthermore, like the mirror 71b shown in FIG.
The light beam is reflected multiple times in the space between the reflecting mirror rotated by the rotating means and the photoreceptor, and by creating a configuration in which there is only one mirror that reflects multiple times on the same surface, the number of mirrors can be reduced and the overall can be made compact.

Furthermore, the chassis of the optical system may be located on the opposite side of the mounting surface, and the chassis may also serve as a cover. This allows the number of parts and assembly man-hours to be reduced.

Furthermore, the reflecting mirror rotated by the rotating means or the base of the reflecting mirror may be made of resin. This can be expected to improve the mass productivity of reflective mirrors.

FIG. 11 shows the configuration of another embodiment. It is also possible to provide an fθ lens 11 in the space between the reflecting mirror and the photoreceptor, and use this as a second optical system to correct distortion aberration. In this way, it is possible to provide a high-performance optical scanning device with good distortion aberration while having a simple configuration.

Further, the second optical system does not need to have surface tilt correction characteristics.

[0029]

Effects of the Invention As is clear from the above description, the present invention has a light source that oscillates light rays, an optical system lens that converges the light rays, and a reflecting surface that reflects the light rays subjected to the convergence action. A reflector and the light beam reflected by the reflector exit, and the only reflecting surface of the reflector is tilted with respect to the traveling direction of the incident light beam and rotates around the center of the incident light. Since the incident light ray is always reflected from the same part of the reflecting surface, no optical path difference occurs in the reflected light rays, so that printing accuracy is improved. In addition, since the structure of the reflecting mirror is simple and the reflected light beam does not blur in the vertical direction, there is no need for a lens to correct this blurring, making it possible to reduce the size and weight and reduce costs.

Furthermore, since the reflected light is a single surface and does not require surface tilt correction, a cylinder lens is not necessary, and the lens configuration is only a converging lens. Therefore, the configuration can be significantly simplified.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an optical scanning device according to an embodiment of the present invention.

[
FIG. 2: Optical path diagram in an apparatus according to an embodiment of the present invention

[
FIG. 3: A perspective view of essential parts of an apparatus according to an embodiment of the present invention

[Fig. 4] Diagram explaining the operation in one embodiment of the present invention

[Fig. 5] Diagram explaining the operation in the conventional example

FIG. 6 is a side sectional view showing another embodiment of the present invention.

FIG. 7 is a perspective view showing another embodiment of the present invention.

[
FIG. 8 is a configuration diagram showing another embodiment of the present invention

[Fig. 9] Configuration diagram showing a conventional optical scanning device

[Figure 10] Optical path diagram in a conventional device

[Fig. 11] Enlarged view of main parts showing a conventional device

[Explanation of symbols]

1 Light source 2 Lens 9 Reflector

Claims (5)

[Claims] 1. A light source that oscillates a light beam, a converging lens that forms an image of the light beam on a photoreceptor, and a convergent lens that has an inclination with respect to the light beam that has passed through the lens, and that reflects the light beam that has passed through the lens. scanning is performed by rotating the reflecting mirror with a rotating means about the center of the ray of light after passing through the lens as a rotation axis; An optical scanning device. 2. The optical scanning device according to claim 1, wherein the component is integrally provided with a chassis, and the chassis serves as a cover covering an upper surface of the component. 3. In the space between the reflecting mirror rotated by the rotating means and the photoreceptor, there are a plurality of mirrors that reflect the light beam multiple times, and only one mirror that reflects the light beam multiple times exists on the same surface. The optical scanning device according to claim 1, characterized in that: 4. The optical scanning device according to claim 1, wherein the reflecting mirror rotated by the rotating means or the base of the reflecting mirror is made of resin. 5. Optical scanning according to claim 1, characterized in that the second optical system is provided with a lens in the space between the reflecting mirror and the photoreceptor, and the second optical system does not have a surface tilt correction characteristic. Device.