JPH0318810A - Polygon motor - Google Patents

Abstract

PURPOSE:To miniaturize the whole system by installing a laser diode being a light source on a substrate on which a motor driving circuit is mounted. CONSTITUTION:On the inside peripheral surface of a resin formed body 11, reflecting surfaces 12 of six surfaces to which an A1 reflecting film and an SiO2 protective film are brought to coating are provided, and an annular projecting part 13 is installed in order to be joined to a driving motor. Also, the subject motor is structured so that a luminous flux 14 from a light source of a laser diode 17 is reflected by the reflecting surface 12, and deflected by rotating a rotary polygon mirror by a driving motor. In this regard, the laser diode 17 is installed on a substrate on which the circuit of the driving motor is mounted, and in the same way, the circuit for driving the laser diode 17 is also constructed so as to be mounted onto the same substrate. In such a way, the whole system is miniaturized, and the system constitution can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a polygon motor that optically scans a laser beam using a rotating polygon mirror. More specifically, the present invention relates to a polygon motor in which a laser diode is installed within the motor that drives a rotating polygon mirror made of a resin molded body and having a plurality of reflective surfaces on its inner periphery.

[Conventional technology] FIG. 4 shows an external view of a conventional polygon motor.

Optical scanning using the polygon mirror 41 is performed by rotating the polygon mirror 41, which has a plurality of reflective surfaces 42 formed on the outer periphery by precision processing on a material such as aluminum or glass, by a drive motor 43, and scanning from a light source such as a laser diode 44. The beam of light was being scanned. The laser diode was installed outside the motor.

[Problems to be Solved by the Invention] However, as mentioned above, in the conventional polygon motor using a rotating polygon mirror, the light source is located outside the motor, so when used as an optical scanning device for a laser beam printer, for example, After temporarily installing the motor and laser diode on the frame of the main body, it was necessary to adjust the position of the motor or laser diode so that the light beam hits a prescribed position on the photosensitive drum for forming a latent image, and then fix the position.

Furthermore, since the optical system requires a large area, the entire system becomes large.

[Means for Solving the Problems] The polygon motor of the present invention has a plurality of planes on the inner circumference having an inclination angle of 2 degrees or more and less than 80 degrees with respect to the rotation axis, and a metal reflective film is coated on these planes. A polygon motor comprising a rotating polygon mirror made of resin and a drive motor for the rotating polygon mirror is characterized in that a laser diode is installed in the drive motor.

Furthermore, the polygon motor is characterized in that the laser diode and the laser diode drive circuit are installed within a board on which the motor drive circuit is mounted.

[Example] FIG. 1 is a cross-sectional view of a device according to the present invention. Resin molded body 1
1 has six reflective surfaces 12 coated with an A1 reflective film and a SiO2 protective film on the inner peripheral surface thereof, and an annular protrusion 13 is provided for connection with a drive motor. The light beam 14 from the light source of the laser diode 17 passes through the above-mentioned reflecting surface 12.
The beam is reflected by the mirror and deflected by rotating the rotating polygon mirror with a drive motor. The laser diode 17 is installed on a substrate on which a drive motor circuit is mounted. Similarly, the circuit for driving the laser diode is also mounted on the same substrate.

The dimensions of the resin molded body in this example are an outer diameter of 50 mm, an inscribed circle radius r = 8 mm, a thickness t = 8 mm, and an inclination angle of 0245 degrees from the rotation axis.

Next, a method for manufacturing a rotating polygon mirror made of the above-mentioned resin molded body will be described. A resin having a light transmittance of 80% or more was poured into a mold as shown in the cross-sectional view of FIG. 2 to form a resin shape. Since the annular joint with the drive motor can be formed at the same time in the upper mold for molding the reflective surface, the parallelism and coaxiality between the reflective surface and the rotation axis can be formed with high accuracy. In the embodiment, a polymethyl methacrylic resin having high light transmittance and low absorption in the rotating polyhedron was used as the resin, but other resins may be used as long as the resin has a light transmittance of 80% or more.

Next, a method for forming a reflective metal film on the obtained resin molded body will be described. As a pretreatment, the resin molded body is washed to remove surface contaminants. Thereafter, the resin molded body is dried to remove unnecessary water content.

In this state, it is set in an electron beam evaporation apparatus and thoroughly evacuated. As an exhaust system for electron beam evaporation equipment, a diffusion pump alone is insufficient to remove water molecules, so a polycold chiller (trade name) is used in combination with a diffusion pump, or an exhaust system equipped with a cryopump is used. . After sufficient evacuation, silicon monoxide (Sin) 31 is deposited to a thickness of 500 Å, as shown in the partial cross-sectional view of FIG.

Aluminum (Al) is applied as a reflective layer after SiO deposition.
32 was deposited by 1000 people. 81 performance as a rotating polygon mirror is sufficient in this state, but since aluminum is easily oxidized, an SiO protective film 33 of 2000 Å was formed on top of the aluminum layer 32 to ensure reliability. In conventional rotating polygon mirrors that have a reflective film on the outer circumferential surface, if the protective film layer is too thick, it causes a decrease in reflectance.
With the structure of the present invention, the reflective surface is on the inner surface and does not affect the reflectance, so it can be made sufficiently thick and reliability is improved. Furthermore, conventionally, when depositing a metal film and a protective film, it was not possible to form a reflective surface in one step without rotating a rotating polygon mirror, but in the case of the present invention, the reflective surface can be formed by depositing from 34 directions. It can be easily manufactured without a mechanism to rotate the polygon mirror.

[Effects of the Invention] As described above, according to the present invention, the laser diode that is the light source is installed on the board on which the motor drive circuit is mounted, so an optical system that takes up much less space than the conventional one can be realized. This makes it possible to downsize the entire system.

It also eliminates the need for positioning the light source and polygon mirror during system assembly, simplifying the system configuration.

Furthermore, since a rotating polygon mirror made of a resin molded body can be manufactured using only two molds, an upper mold and a lower mold, compared to conventionally proposed products, the coaxiality of the reflective surface and the rotating axis and the mutual interaction of the reflective surfaces are improved. It has the advantage of being easy to manufacture because the positioning of the mold is determined only by the accuracy of one of the molds.

Further, when forming a reflective surface, a metal reflective film and a protective film can be formed without rotating the resin molded body, and productivity is superior to conventional products. Furthermore, since the protective film does not affect the reflection characteristics, it can be made sufficiently thick, and reliability is improved over conventional products.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a polygon motor of the present invention. FIG. 2 is a schematic cross-sectional view of the mold. Figure 3 shows A partial cross-sectional view of a rotating polygon mirror. Figure 4 shows Optical scanning device using conventional rotating polygon mirror Schematic diagram. that's all

Claims (2)

[Claims] (1) A rotating polygon mirror made of resin, which has a plurality of planes on its inner circumference with an inclination angle of 2 degrees or more and less than 80 degrees with respect to the rotation axis, and a metal reflective film is provided on the planes, and the rotating polygon. A polygon motor comprising a mirror drive motor, characterized in that a laser diode is installed inside the motor. (2) The polygon motor according to claim 1, wherein the laser diode and the laser diode drive circuit are installed within a board on which a motor drive circuit is mounted.