JPH0638481A - Brushless servo motor - Google Patents

Abstract

PURPOSE:To satisfactorily control a rotation by reducing in size an apparatus and accurately detecting a rotating speed signal. CONSTITUTION:A brushless servo motor comprises annular detecting coil members 20 provided on flat driving coils 12 annularly disposed on a motor board 10 in an insulating manner, and a rotor 30 having an annular driving main magnet 33 mounted at a position opposed to the members 20 thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin brushless servomotor suitable for use in, for example, driving a floppy disk.

[0002]

2. Description of the Related Art Conventional brushless servomotors are
For example, as shown in FIG. 5, a motor substrate 1, a rotor 3 rotatably supported by the motor substrate 1 via a bearing portion 2, an annular main magnet 4 supported by the rotor 3 and integrally provided, and A power generation magnet (FG magnet) 5, a plurality of flat drive coils 6 provided on the motor substrate 1 so as to face the lower surface of the rotor 3, and a pattern formed on the motor substrate 1 so as to face the power generation magnet 5. And a coil 7 for power generation.

With the above-mentioned structure, the rotor 3 is rotated by the repulsive force generated between the flat drive coil 6 and the main magnet 4 when a drive current is applied to the flat drive coil 6, and this rotation causes the rotor 3 to rotate. A rotation speed signal induced between the power generation coil 7 and the power generation magnet 5 is obtained, the drive current is controlled so that the rotation speed signal matches the set speed signal, and the rotor 3 is always rotated at a constant speed. Is configured to.

[0004]

In the above-mentioned conventional structure, the power generation coil 7 is located on the outer periphery of the flat drive coil 6 on the motor substrate 1 and therefore has the following problems.

First, since the power-generating coil 7 is located on the outer periphery of the flat driving coil 6, the motor substrate 1 to be used is inevitably increased accordingly, which hinders downsizing of the device.
On the contrary, when the size of the motor substrate 1 is constant, the flat drive coil 6 needs to be designed small, and in that case, the rotation performance of the motor is deteriorated.

Also, the connection land 9 of the flat driving coil 6
Etc. are provided in the ring-shaped power generation coil 7, the power generation coil 7 forms an open coil P at that portion in order to draw it out to the outside, and for this reason the rotation speed signal as a normal detection signal. Was not obtained, and the rotation accuracy was reduced. That is, if the open coil P is present in the power generation coil 7, the rotational speed signal obtained at that portion decreases, and in that case, when the rotor 3 rotates while rattling, the power generation magnet 4 causes the open coil portion of the power generation coil 7 to rotate. Because it rotates while approaching and separating repeatedly, the amount of rotation speed signal obtained with time increases and decreases,
As a result, in the rotation speed signal, as shown in FIG.
Distortion will occur. When the rotation speed signal is distorted in this manner, the matching operation with the set speed signal is not normally performed, and the rotation accuracy is reduced.

The present invention has been made by paying attention to such an actual situation, and makes it possible to downsize the equipment, and at the same time, a brushless servo in which the rotation speed signal is accurately detected and the rotation control is performed well. The purpose is to provide a motor.

[0008]

In order to achieve the above object, the brushless servomotor of the present invention is provided with a bearing portion, and a plurality of flat driving coils are annularly arranged so as to surround the bearing portion. A motor substrate configured as described above, and an annular detection coil member that is provided insulatively on each of the flat drive coils arranged in the annular shape,
The rotor is rotatably supported by the bearing portion, and the rotor is provided with an annular driving main magnet at a position facing the detection coil member.

[0009]

According to the above structure, since the annular detection coil member is provided insulatively on each of the flat drive coils arranged in an annular shape, the detection coil arrangement on the motor substrate which has been conventionally required is required. Space is reduced.

Further, since the detection coil member is annular and there is no open coil, the rotation speed signal as a detection signal does not decrease.

[0011]

1 is an exploded perspective view of a brushless servomotor according to the present invention, and FIG. 2 is a sectional view of the brushless servomotor.

In these drawings, reference numeral 10 is a motor substrate. The motor substrate 10 is provided with a rotor bearing portion 11 to be described later, and a plurality of flat drive coils 12 are provided so as to surround the bearing portion 11. Hall element 1
An annular drive coil member 14 configured by combining 3 and 3 is provided, and an oscillator 15,
An output circuit element 16, a drive control IC 17 and the like are mounted.

A detection coil member 20 is formed by printing a coil pattern 21 on the surface of an annular insulating sheet and providing an overcoat layer on the upper surface thereof. This detection coil member 20 is the drive coil member. It is provided by being adhered onto 14 by an adhesive.

Reference numeral 30 denotes a rotor, and the rotating shaft 3 is provided at the center of the lower surface.
1 is projectingly provided, and an annular driving main magnet 33 is mounted on the lower surface around the rotary shaft 31. The rotor 30 has a rotary shaft 31 having the bearing portion 1 described above.
It is rotatably provided by being supported by the bearing 1, and the drive main magnet 33 faces the detection coil member 20 in that state.

As described above, by disposing the detecting coil member 20 relative to the main magnet 33, the main magnet 33 is also used as a conventional power generating magnet, and the coil pattern of the detecting coil member 20 is used. Since the motor board 21 is not formed on the motor board 1, the area of the motor board 10 can be reduced accordingly, and the coil pattern 21 is formed without providing the open coil portion.

FIG. 3 is a block diagram of the brushless servomotor. The output circuit element 16 for performing a power supply output operation to the flat drive coil 12 to the drive control IC 17, the oscillator 15, and the detection coil member 20, Each of them is connected to the hall element 13.

The operation will be described below.

A drive control signal from the drive control IC 17 gives a drive current to the flat drive coil 12 via the output circuit element 16, whereby the flat drive coil 1 is supplied.
2 is driven, a repulsive force is generated between the driving magnet 2 and the driving main magnet 33, and the rotor 30 rotates. The basic rotation control at this time is performed based on the rotation position detection signal from the hall element 13. Next, when the rotor 30 rotates, a rotation speed signal as a detection signal is generated between the detection coil member 20 and the driving main magnet 33. This rotation speed signal is shown in FIG. 4A because the coil pattern 21 of the detection coil member 20 does not have an open coil portion.
As shown in, a distortion-free one is always obtained.

When the rotation speed signal thus obtained is different from the set speed signal from the oscillator 15,
A drive control signal is output from the drive control IC 17 so that they coincide with each other, whereby the drive current from the output circuit element 16 is controlled and the rotor 30 always rotates at a constant speed.

[0020]

As described above, according to the present invention,
Since the annular detection coil member is provided insulatively on each of the flat drive coils arranged in an annular shape, the arrangement space of the detection coil on the motor board, which is conventionally required, is reduced, and thus the device is reduced. Can be downsized.

Further, since the detection coil member is annular and there is no open coil, the rotation speed signal as a detection signal at that portion does not decrease at the time of rotor rotation, so that the rotor rotates with rattling. Even in such a case, the rotation speed signal can be stably obtained, and as a result, the rotation speed control can be accurately performed.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a brushless servomotor according to the present invention.

FIG. 2 is a sectional view of a brushless servomotor according to the present invention.

FIG. 3 is a block diagram of a brushless servomotor according to the present invention.

FIG. 4 is an explanatory diagram of a rotation speed signal.

FIG. 5 is an exploded perspective view of a conventional brushless servomotor.

[Explanation of symbols]

 10 Motor Board 11 Bearing Part 12 Flat Driving Coil 20 Detection Coil Member 30 Rotor 33 Driving Main Magnet

Claims (1)

[Claims] 1. A motor substrate having a bearing portion and a plurality of flat drive coils annularly arranged so as to surround the bearing portion, and each of the flat drive coils arranged annularly. An annular detection coil member provided in an insulating manner on the above, a rotor rotatably supported by the bearing portion, and a rotor having an annular driving main magnet mounted at a position facing the detection coil member, A brushless servomotor equipped with.