JPH03282511A - Optical scanning device - Google Patents

Abstract

PURPOSE:To improve the scanning accuracy by fitting a rotary polygon mirror to the rotor yoke of a scanner motor or the outer periphery of a magnet. CONSTITUTION:A printed board 2 is mounted on a fixed housing 1 and a stator coil 3 is wound on a substrate 2. A rotary shaft 5 is supported on this housing 1 accross upper and lower bearings 4a and 4b and a rotor 7 is fixed on the rotary shaft 5 through a bracket 6. This rotor 7 is provided with the rotor yoke 8, whose surface facing the stator coil is magnetized in specific pattern to constitute a permanent magnet. The the rotary polygon mirror 10 is mounted on the outer periphery of the yoke 8. This rotary polygon mirror 10 is constituted by vapor-deposition an AlO2 film 13 on the surface of a regular polygonal annular body 11. Consequently, the scanning accuracy can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical scanning device, and particularly to an optical scanning device in which a rotating polygon mirror is rotated by a scanner motor to linearly scan a laser beam on a scanning surface. Regarding equipment.

[Prior Art] A laser beam printer irradiates a rotating polygon mirror with a laser beam projected from a semiconductor laser unit, deflects it, and then scans the surface of a photoconductor at a constant speed through a condensing scanning lens to write and print. It was designed to do this. The rotating polygon mirror is fixed on the rotating shaft of the scanner motor and rotated at equal angles, and is required to have high deflection angle accuracy and accurate rotation performance.

In conventional scanner motor devices, the rotating polygon mirror is either fitted onto the rotating shaft of the motor and fixed with a set screw, or a flange is integrally formed on the rotating shaft, and the flange is attached to a surface. The rotating polygon mirror is attached tightly using spring washers. (Refer to Japanese Utility Model Publication No. 1287/1987) [Problems to be Solved by the Invention] In the conventional optical beam scanning device described above, a rotating polygon mirror is mounted on the output shaft of the motor at a position away from the center of the motor. Because of this, the axial dimension tends to increase, and as it moves away from the center of the motor, the amount of deflection of the rotating polygon mirror increases, resulting in poor scanning accuracy. In addition, parts such as mirror retaining springs, mirror retaining screws, and mounting screws are required to secure the rotating polygon mirror to the shaft of the motor, and the installation process using these parts is indispensable for assembly.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical scanning device in which the mounting position of a rotating polygon mirror is brought closer to the center of the motor to reduce vibration and improve accuracy, and the number of parts for mounting is reduced.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides an optical scanning device in which a rotating polygon mirror is rotated by a scanner motor to scan a laser beam on a scanning surface. is attached to the rotor yoke of the scanner motor or the outer periphery of the magnet.

[Function] According to the present invention, when the scanner motor is rotated, the rotating polygon mirror rotates together with the rotor, and the laser beam irradiated on the rotating polygon mirror is directed in a straight line on the scanning surface. can be scanned in a specific manner.

[Embodiment] An embodiment of the optical scanning device according to the present invention will be described below with reference to the drawings.

FIG. 1 shows an example in which the present invention is applied to an axial brushless DC motor. Reference numeral 1 indicates a fixed housing, and a printed circuit board 2 is mounted on the fixed housing 1. Although not shown, electronic components constituting the drive circuit are mounted. Also,
A stator coil 3 is wound on the printed circuit board 2.

A rotary shaft 5 is rotatably supported in the housing 1 via an upper bearing 4a and a lower bearing 4b. A rotor 7 is fixed onto the rotating shaft 5 via a bracket 6. The rotor 7 has a rotor yoke 8, and the surface of the rotor yoke 8 facing the stator coil is magnetized in a predetermined pattern to constitute a permanent magnet.

According to the present invention, the rotary polygon mirror 1 is provided on the outer periphery of the rotor yoke 8.
0 is installed. This rotating polygon mirror 10 has AIt on the surface of a regular polygonal annular body 11, as shown in FIG.
It is constructed by depositing an O2 film 13. This annular body 11 is glued or press-fitted onto the outer peripheral surface of the rotor yoke 8.
It can be fixed by means such as shrink fitting.

Furthermore, according to another embodiment of the present invention, as shown in FIG. 3, the rotor yoke 8 itself may be formed in advance into a regular polygon, and the A I O2 film 13 may be formed on the surface thereof. good.

FIG. 4 shows an example in which the present invention is applied to a radial brushless DC motor, in which the fixed housing 14 is connected to the hub 15.
and a flange 16.

A stator core 17 is provided around the hub 15, and an armature coil 12 is wound around this core. A rotating shaft 20 is rotatably supported at the center of the hub 15 via upper bearings 18a and 18b. A rotor yoke 22 is fixed to the rotating shaft 20 via a flange 21, and a rotor coil 23 is wound inside the rotor yoke 22. Further, a rotating polygon mirror 24 is mounted on the outer periphery of the rotor yoke in the same manner as in the previous embodiment.

Further, a reflective photo encoder 25 is provided on the upper surface of the fixed housing 14 in close proximity to the rotating polygon mirror, so that the rotational position of the rotor can be detected and the speed of the scanner motor can be controlled.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, since the rotating polygon mirror is directly attached to the rotor yoke or magnet, the rotating polygon mirror can be installed at a position close to the center of the scanner motor in the axial direction. The scanning accuracy can be improved by reducing the shake of the image. Further, since the rotating polygon mirror does not protrude outward in the axial direction of the motor as in the conventional case, the length in the axial direction can be shortened and the motor can be configured compactly.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example in which the optical scanning device according to the present invention is applied to an axial motor, Fig. 2 is a plan view of a rotating polygon mirror, and Fig. 3 is a plan view showing another example of the rotating polygon mirror. , 4th
The figure shows an example in which the present invention is applied to a radial motor.・1
It is also a side view. 7... Rota, 8... Rota yoke, 10... Rotating polygon mirror, 11... Annular body.

Claims (1)

[Claims] An optical scanning device in which a rotating polygon mirror is rotated by a scanner motor to scan a laser beam on a scanning surface, characterized in that the rotating polygon mirror is attached to the rotor yoke of the scanner motor or the outer periphery of a magnet. .