JPS6392913A - Optical recorder - Google Patents

Abstract

PURPOSE:To remove changes in the thickness of lines constituting a character by providing the titled device with a light energy adjusting means for changing the attenuation factor of light energy along a scanning direction in accordance with the incident angle of projected light on a polygonal mirror. CONSTITUTION:A laser beam generated from a laser block 1 is reflected by the polygonal mirror 2 and used for scanning at a fixed period. At that time, the laser beam is changed at is intensity due to a difference in the passing distance of a coating layer based on a difference in the incident angle of it upon the polygon mirror 2. The laser beam changed in its direction by the polygonal mirror 2 is corrected by a ftheta lens in accordance with the difference of a focal distance up to a recording body 5, changed in its direction by a reflection mirror 6, corrected in accordance with the distribution of energy after its reflection based on the polygonal mirror 2, and then forms its image on the recording body 5 under uniform energy distribution to record data in the recording body 5. Consequently, the thickness of lines constituting a character is not changed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to optical recording devices such as copying machines and laser printers.

2. Description of the Related Art Conventionally, optical recording devices that scan a photoreceptor with light to form an electrostatic image are often configured to scan light using a reflector such as a rotating polyhedral mirror.

FIG. 2 is a perspective view of a conventional optical recording device, in which 1 is a laser block having a semiconductor laser (not shown) and a collimator lens that converts the laser beam generated by the semiconductor laser into parallel light; Transparent 8I fat i' to protect the surface! A coating layer (omitted in the figure) is formed, and a polyhedral mirror (hereinafter abbreviated as polygon mirror) that successively changes the direction of the laser beam generated by the laser block 1 and reflects it, 3 is a polygon. A motor rotates the mirror 2, 5 is a recording medium that is scanned by a laser beam, and 4 is an f for focusing the laser beam deflected by the polygon mirror 2 on the surface of the recording medium 5.
The θ lens 6 is a reflecting mirror that is provided between the fθ lens 4 and the recording medium 5 and changes the direction of the laser beam.

Generally, the intensity of laser light has a Gaussian distribution as shown in FIG. In the figure, I is the power density, io is the maximum power density, W is the beam diameter of the laser beam, and the power density at this position is I.

/e becomes.

The operation of the optical recording apparatus configured as described above will be explained below.

The laser beam generated by the laser block 1 is reflected by the polygon mirror 2 which is driven and rotated by the motor 3.
Scanned at regular intervals. The laser beam reflected by the polygon mirror 2 is corrected by the fθ lens according to the difference in focal length to the recording medium 5, and after being changed in direction by the reflecting mirror 5, it forms an image on the recording medium 5. Recording is performed on the recording medium 5.

Problems to be Solved by the Invention However, in the above-mentioned conventional configuration, the distance that the laser beam passes through the coating layer of the polygon mirror 2 changes depending on the angle of incidence on the polygon mirror 2. The amount of energy loss of the light changes, the intensity of the laser light changes, and the intensity distribution of the laser light whose direction is changed by the polygon mirror 2 becomes non-uniform along the scanning direction. That is, the laser beams incident at positions ASB and C on the surface of the recording medium 5 shown in FIG. The light incident on the polygon mirror 2 at the position C has a small passing distance through the coating layer, and conversely, the light incident on the polygon mirror 2 at a large incident angle that is irradiated to the position C has a large passing distance through the coating layer. As shown in Figure (b), when comparing the energy PO of the light irradiated to position B and the energy P of the light irradiated to position C, PO is larger and the energy distribution of the light irradiated to the recording medium 5 is is uneven.

FIG. 5 shows the intensity distribution of the laser beam at positions B and C shown in FIG. Recording is performed when the beam is irradiated. Therefore, at position B, the beam diameter involved in recording is w
b, whereas at position C, the beam diameter is WC,
As shown in FIGS. 6(a) and (b), position B and position lI'
Even if the same characters were recorded using [c], the lines composing the characters would have different thicknesses, which adversely affected the print quality.

Means for Solving the Problems The present invention is equipped with a light energy adjusting means that changes the attenuation rate of light energy along the scanning direction in accordance with the angle of incidence of the irradiated light on the polyhedral mirror. It is.

Operation: With the above configuration, the intensity of the laser beam on the surface of the recording medium is constant.

Embodiment FIG. 1(a) is a block diagram of an optical recording apparatus according to an embodiment of the present invention, in which 1 is a laser block, 2 is a polygon mirror, 4 is an fθ lens, and 5 is a recording medium, which are conventional The configuration is similar to the example. Reference numeral 6 denotes a reflective mirror made of resin with a metal film formed on its surface by vapor deposition. The thickness of the metal film changes along the scanning direction so that it becomes thicker where light with a large incident angle is irradiated, and the reflection mirror 6 has a reflectance as shown in FIG. 1(c). It is configured to have a distribution.

The operation of the optical recording apparatus of this embodiment configured as described above will be described below.

A laser beam generated by a laser block 1 is reflected by a polygon mirror 2 and scanned at a constant period. At this time, as in the conventional example, the intensity of the laser beam changes as shown in FIG. 1(b) due to the difference in the passing distance of the coating layer due to the difference in the angle of incidence on the polygon mirror 2. The laser beam whose direction has been changed by the polygon mirror 2 is corrected by the fθ lens according to the difference in focal length to the recording medium 5, and the direction is changed by the reflection mirror 6. At the same time, the laser beam after being reflected by the polygon mirror 21 is After the correction corresponding to the energy distribution is performed, the recording medium 5 is placed in a state where the energy distribution is uniform as shown in FIG. 1(c).
An image is formed on the recording medium 5, and recording is performed on the recording medium 5.

In this embodiment, since the energy of the laser beam is uniform on the surface of the recording medium 5, the thickness of the lines constituting the characters does not change as in the conventional case, and high printing quality can be obtained.

In this example, a reflector whose reflectance was changed by depositing metal in multiple layers was used as a means of adjusting the energy of the laser beam, but this was achieved by coating the mirror surface with multiple layers of transparent resin, and adding a coating layer. A reflecting mirror whose light absorption rate is changed by changing the thickness of the mirror may be used. Further, as this adjustment means, it is also possible to use a filter whose light transmittance is changed.

Effects of the Invention The present invention includes a light energy adjusting means that changes the attenuation rate of the energy of the light in accordance with the angle of incidence of the irradiated light on the polyhedral mirror, so that the intensity of the light irradiated onto the surface of the recording medium is adjusted. Since the thickness is constant, it is possible to obtain an excellent optical recording device in which the thickness of the lines constituting the characters formed on the surface of the recording medium does not change.

[Brief explanation of the drawing]

FIG. 1(a) is a block diagram of an optical recording device according to an embodiment of the present invention, FIG. 1(b) is a distribution diagram of the intensity of the laser beam after passing through the same fθ lens, and FIG. 1(c) is the same. FIG. 1(d) is a characteristic diagram showing the reflectance of the reflecting mirror, FIG. 1(d) is a distribution diagram of the intensity of the laser beam on the same recording medium, FIG. Intensity distribution map of the same laser beam, Figure 4 (
a) is a block diagram of the device, FIG. 4(b) is a diagram of the intensity distribution of the laser beam on the recording medium, and FIG. 5 is a characteristic diagram showing changes in intensity at the center and edge of the recording medium. FIG. 6(a) is a plan view showing the recording state at the center, and FIG. 6(b) is a plan view showing the recording state at the end. 1...Laser block, 2...Polygon mirror, 4...Fθ lens, 5...Technical record book, 6...Reflection mirror fee J! Name of the person Patent attorney Toshio Nakao and one other person Drawing details (no changes to the contents) 4-fθ lens B ° Recone ξ error f: 83 Figure f--7 Figure 5 Figure 6 Procedural amendment (direction p November 1988 10E) 1988 Patent Application No. 145248 2. Name of the invention Optical recording device 3. Relationship with the person making the amendment Patent application Colonel Address 1006 Oaza Kadoma, Kadoma City, Osaka Name (582) Representative of Matsushita Electric Industrial Co., Ltd.
Akio Tanii 4 Agent 571 Address 1006 Oaza Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Date of 5 Amendment Order

Claims (3)

[Claims] (1) A light generator, a polyhedral mirror that rotates driven by a motor or the like and reflects the light generated from the light generator in periodically changing directions, and is placed in the optical path of the light reflected by the polyhedral mirror. and a light energy adjusting means that has a large attenuation rate in a portion of the polyhedral mirror irradiated with light having a small incident angle and a small attenuation rate in a portion irradiated with light with a large incident angle. Device. (2) The optical recording device according to claim 1, wherein the light energy adjusting means is a reflecting mirror whose reflectance is changed in accordance with the incident angle of the light onto the polyhedral mirror 1. (3) The optical recording device according to claim 1, wherein the light energy adjusting means is a filter whose transmittance is changed in accordance with the angle of incidence of light on the polyhedral mirror.