JPH069371U - Polygon mirror drive - Google Patents

Abstract

(57) [Abstract] [Purpose] The number of air-core windings of a flat type three-phase brushless motor in a polygon mirror driving device used in OA equipment such as a laser beam printer is reduced to effectively use the vacant space. Moreover, it is small and maintains excellent characteristics. In a polygon mirror driving device in which a polygon boss is fixed to a rotor having a rotor boss, a rotor yoke, and a rotor magnet 5 fixed to the shaft, and the shaft is used as a rotation axis, the rotor magnet 5 has N and S open angles. Is composed of 2P (P is an even number equal to or larger than 4) magnetic poles, and 3P / 4 air-core windings 6 are arranged so as not to overlap the open angle of the magnetic poles.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a polygon mirror driving device equipped with a flat type three-phase brushless motor that rotates a polygon mirror stably at high speed.

[0002]

[Prior art]

 In recent years, polygon mirror driving devices have been increasingly used in office automation (OA) devices such as laser beam printers, laser fax machines, and digital copying machines. Flat polygonal three-phase brushless motors are mainly used for driving polygon mirrors in terms of high speed, high accuracy, and controllability.

The polygon mirror driving device will be described below. FIG. 3 is a structural sectional view of a polygon mirror driving device. In FIG. 3, 1 is a shaft, 2 is a rotor boss, 3 is a polygon mirror, 4 is a rotor yoke, and 5 is a rotor magnet. Further, 6 is an air-core winding, 7 is a stator yoke, and 8 is a substrate.

FIG. 4 is a plan view of a flat type three-phase brushless motor of a conventional polygon mirror driving device, in which a rotor magnet 5 and an air-core winding 6 are arranged and fixed on a substrate 8. Reference numeral 9 is a position detecting element.

The operation of the polygon mirror driving device configured as described above will be described. First, with the shaft 1 as a rotation axis, a rotor boss 2 having a rotor yoke 4 and a rotor magnet 5 fixed to the shaft 1 forms a rotor, and a stator yoke 7 facing the rotor magnet 5 forms a closed magnetic circuit. A switch that is switched by a signal detected by the position detection element 9 in the air-core winding 6 arranged and fixed on the substrate 8 at a uniform angle supplies a current to the air-core winding 6 to rotate the rotor. Then, the polygon mirror 3 is fixed to the rotor and both are rotationally driven.

[0006]

[Problems to be solved by the device]

 However, in the above-described conventional configuration, for the magnetic poles 2P of the rotor magnet 5 (where P is an even number of 2 or more), 3P / 2 air-core windings 6 arranged and fixed on the opposing substrate 8 are provided. There is. Therefore, since the air-core winding 6 is arranged over the entire surface of the substrate 8, the position of the position detecting element 9 and the position of the solder processing portion at the end of the air-core winding 6 are limited, which is troublesome. Further, there is a problem in that there is little freedom in arrangement, and automation and miniaturization are difficult due to the large number of solder processing portions.

The polygon mirror driving device is a device that rotates the polygon mirror stably at high speed and with high precision, and does not require an external load, and thus does not require high torque.

The present invention solves the above-mentioned problems of the prior art, and is a flat type that can reduce the number of air-core windings by easily limiting the position of the position detection element 9 and soldering each end of the air-core winding 6. An object of the present invention is to provide a polygon mirror driving device equipped with a three-phase brushless motor.

[0009]

[Means for Solving the Problems]

 The present invention is a polygon mirror driving device in which a rotor boss, a rotor yoke, a rotor magnet, and a polygon mirror are coaxially fixed to a shaft, and the rotor magnet and an air-core winding face each other. It is composed of a rotor magnet consisting of 2P magnetic poles (where P is an even number of 4 or more) and 3P / 4 air-core windings arranged so as not to overlap the opening angle of the magnetic poles. There is.

[0010]

[Action]

 According to the present invention, the number of air-core windings can be reduced to half that of the conventional one, so that the position detecting element and the solder processing part of the air-core winding terminal are arranged at the place where the air-core winding is removed. Since it can be installed, the degree of freedom is increased, and the automation of soldering process is facilitated. Also, the cost can be reduced by halving the number of air-core windings. Moreover, the circuit driving parts other than the position detecting element can be arranged at the place where the air-core winding is removed, and the polygon mirror driving device can be further downsized.

[0011]

【Example】

 FIG. 1 is a motor plan view of a polygon mirror driving device according to a first embodiment of the present invention. As shown in FIG. 1, when the number of magnetic poles of a rotor magnet 5 is 8 (2P when P = 4). This is an embodiment, and three air-core windings 6 facing the rotor magnet 5 are arranged (3P / 4 when P = 4). The air-core windings 6 are installed and fixed at 120 ° intervals so that they do not overlap the opening angle of the rotor magnet net 5 equally. The position detecting elements 9 are arranged between the air-core windings 6 at intervals of 120 ° with the same pitch.

In this way, the position detecting element 9 can be arranged at the place where the air-core winding 6 is removed, and if necessary, circuit driving parts can be arranged. Then, the degree of freedom in arranging the position detecting element 9 and the solder processing portion of the terminal of the air-core winding 6 and the like is increased, and automation of this solder processing and the like is facilitated.

The operation of the polygon mirror driving device configured as described above will be described. First, the position detecting element 9 detects the magnetic pole of the rotor magnet 5, and the air-core winding 6 is sequentially switched by a switching transistor or the like to cause a current to flow through the air-core winding to drive the rotor. These are three-phase driving operations, and the principle operation is omitted in the present invention.

FIG. 2 is a motor plan view of a polygon mirror driving device according to a second embodiment of the present invention. As shown in FIG. 2, the number of magnetic poles of the rotor magnet 5 and the number of air-core windings 6 are the same as in FIG. Is. The difference from the configuration of FIG. 1 is that the air-core windings 6 are all arranged on the semi-circle side of the concentric circles, and the control circuit components are arranged on the semi-circle side without the air-core windings.

[0015]

As described above, the polygon mirror driving device of the present invention has the number of magnetic poles 2P (P is an even number of 4 or more) with the same opening angle of the rotor magnet 5, and the air-core winding 6 has the magnetic poles. The number of air-core windings is reduced by half and the degree of freedom of the arrangement including the position detection element 9 is increased by being composed of 3P / 4 pieces that are arranged so as not to overlap the open angle equally. It is possible to realize an excellent polygon mirror driving device that facilitates the soldering process of the terminal and can downsize the motor unit.

[Brief description of drawings]

FIG. 1 is a motor plan view of a polygon mirror driving device according to a first embodiment of the present invention.

FIG. 2 is a motor plan view of a polygon mirror driving device according to a second embodiment of the present invention.

FIG. 3 is a structural cross-sectional view of a polygon mirror driving device.

FIG. 4 is a plan view of a flat type three-phase brushless motor of a conventional polygon mirror driving device.

[Explanation of symbols]

3 ... Polygon mirror, 4 ... Rotor yoke, 5 ... Rotor magnet, 6 ... Air core winding, 8 ... Substrate, 9 ... Position detection element.

Claims (1)

[Scope of utility model registration request] 1. A polygon mirror driving device in which a rotor boss, a rotor yoke, a rotor magnet, and a polygon mirror are coaxially fixed to a shaft, and the rotor magnet and an air-core winding face each other. A rotor magnet composed of 2P magnetic poles (where P is an even number of 4 or more) and 3P / 4 air-core windings arranged so as not to overlap the opening angle of the magnetic poles. Characteristic polygon mirror drive device.