JP2569859Y2 - Light beam scanning device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light beam scanning apparatus used for a recording apparatus such as a laser beam and having a polygon mirror fixed to a rotating shaft rotating at a high speed.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, such a light beam scanning device 1 includes a polygonal rotary polygon mirror 2 having a mirror surface on the side and a rotary shaft 3 to which the rotary polygon mirror 2 is fixed. There is a motor provided with a brushless motor 4 that rotates at high speed and high accuracy (for example, see Japanese Utility Model Publication No. 63-1287).

A brushless motor 4 has a bottomed cylindrical casing 5a, 5b superimposed in two stages, and a bearing housing fixed to the upper casing 5a and supporting the rotary shaft 2 via bearings 6a, 6a. 6, a stator 7 fixed to the outer periphery of the bearing housing 6 and having a coil 7a wound around a salient pole, and a yoke 8 fixed to the upper part of the rotating shaft 2.
A magnet 8 a fixed to the inner peripheral surface of the yoke 8 so as to face the stator 7, a rotational position detecting disk 9 attached to the lower end of the rotating shaft 2, and a rotation facing the disk 9. A magnet 8a is rotated integrally with the rotating shaft 2 by energizing the coil 7a, and the rotation of the rotating shaft 2 causes the rotating polygon mirror 1 to rotate at high speed to scan the light beam. .

[0004]

By the way, the rotation driving device used in the light beam scanning device has less rotation unevenness and rotation blur when rotating the rotating shaft 3, and furthermore, the rotation of the oil from the bearing portion. High-speed rotation without scattering (400
(0 rpm or more) is required.

However, in the light beam scanning device 1 configured as described above, since the yoke 8 is rotated integrally with the rotating shaft 3 to satisfy such conditions, it is difficult to set the balance of the rotating shaft 3. In addition, a drive circuit (not shown) for controlling the energization of the coil 7a based on the rotation detection result from the sensor 10 is required, which not only raises the cost of parts, but also generates heat in the circuit due to heat generated by the drive circuit. In addition, there is a problem that the noise easily leaks and is difficult to handle due to a gap between the yoke 8 and the upper casing 5a.

In view of the above situation, the present invention not only can facilitate the setting of the balance of the rotating shaft, but also can reduce the cost of parts, and can prevent output saturation and noise leakage. It is an object of the present invention to provide a light beam scanning device capable of performing the above.

[0007]

According to the present invention, in order to achieve the object, a rotating shaft on which a rotating polygon mirror for scanning a light beam is fixed and an inner peripheral surface of a yoke casing which supports the rotating shaft are fixed. The rotating polygon mirror is rotated at high speed by the driving force of a brush-equipped rotary drive device including the magnet provided and a rotor core fixed to the rotating shaft and facing the magnet.

[0008]

In such a configuration, the rotary polygon mirror for light beam scanning fixed to the rotary shaft is rotated at high speed by the driving force of the rotary drive device with brush.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the light beam scanning device according to the present invention will be described with reference to the drawings.

In FIG. 1, a light beam scanning device 11 comprises:
A polygonal rotary polygonal mirror 12 having a mirror surface on the side, and a DC motor 1 as a rotary drive device with a brush for rotating a rotary shaft 13 on which the rotary polygonal mirror 12 is press-fitted and fixed with high speed and high accuracy.
4 is provided.

The DC motor 14 has a yoke casing 1 for fixing a magnet 16 on its inner peripheral surface 15a and rotatably supporting an upper portion of a rotating shaft 13 via a bearing 17.
5. The thrust bearing plate 18 fitted to the lower part of the yoke casing 15 so that the lower end of the rotating shaft 13 abuts, the rotor core 20 fixed to the rotating shaft 13 and the coil 19 wound around the salient pole, FG magnet 21 for rotation position detection fixed to the lower end, FG sensor 22 for rotation detection facing FG magnet 21, brush holder 24 for supporting lower part of rotation shaft 13 via bearing 23, rotation shaft 13
And a brush spring (including a brush) 26 attached to a brush holder 24 so as to press against the commutator 25.

The rotor core 20 has a rotating shaft 13 with the magnetic center of the magnet 16 shifted (in the illustrated example, upward).
The rotational center 13 is always attracted in one direction by shifting the magnetic center, and the supporting force of the thrust receiver is improved.

In the above configuration, when the rotating shaft 13 is rotated at a high speed by the current flowing through the coil 19 and the magnetic force of the magnet 16 while controlling the rotation, the rotating polygon mirror 12 rotates at a high speed integrally with this rotation, and the The beam is scanned.

At this time, since the DC motor 14 is an inner rotor type brush motor, the balance of the rotating shaft 13 is good, rotation unevenness and rotation blur are small, and a driving circuit is not required.

[0015]

As described above, in the light beam scanning device of the present invention, the rotating shaft on which the rotating polygon mirror for scanning the light beam is fixed, and the inner peripheral surface of the yoke casing that supports the rotating shaft. The rotating polygon mirror is rotated at high speed by the driving force of a brush-equipped rotary driving device having a magnet fixed to the rotating shaft and a rotor core fixed to the rotating shaft and facing the magnet, thereby facilitating balance setting of the rotating shaft. Not only can be realized, but also the cost of parts can be reduced, and further, adverse effects on performance and noise leakage can be prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of the light beam scanning device of the present invention.

FIG. 2 is a longitudinal sectional view of a main part of a conventional light beam scanning device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Light beam scanning device 12 ... Rotating polygon mirror 13 ... Rotating shaft 14 ... DC motor (rotation drive device with a brush) 15 ... Yoke casing 15a ... Inner peripheral surface 16 ... Magnet 20 ... Rotor core 26 ... Brush spring

Claims (2)

(57) [Scope of request for utility model registration] 1. A rotating shaft to which a rotating polygon mirror for scanning a light beam is fixed, a magnet fixed to an inner peripheral surface of a yoke casing that supports the rotating shaft, and a magnet fixed to the rotating shaft and the magnet. A light beam scanning device, wherein the rotary polygon mirror is rotated at a high speed by the driving force of a rotary drive device with a brush having opposed rotor cores. 2. The light beam scanning device according to claim 1, wherein the magnet and the rotor core are provided with their magnetic centers shifted.