JPH06174410A - Position detecting device - Google Patents

Abstract

PURPOSE:To reduce the number of part items and the production cost of a position detecting detector and miniaturize it by providing a position detecting magnetic means on the end face at the center section of driving magnetic poles, and providing a driving magnetic detecting means concurrently detecting the driving magnetic field and the position detecting magnetic field. CONSTITUTION:When voltage is applied to driving coils L to rotate a rotor 2, N-poles and S-poles of rotor magnets 2a are faced to hole elements 4 in turn, and a position detecting magnetization 2b is faced to output a sine wave having a pulse-like peak once per rotation. The peak of the output signal is removed by a hole signal differential amplifier 8, and it is inputted to a motor driving circuit 6 to rotate the rotor 2. The sine wave having the pulse-like peak is amplified as it is by a linear amplifier 7, it is compared by a differential amplifier 9 with the sine wave removed with the peak, and the wave-form signal having the peak is extracted. When this wave-form signal is shaped by a wave-form shaping amplifier 10, the position detecting pulse signal can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting device,
More specifically, it relates to a device for detecting the position of a motor rotor.

[0002]

2. Description of the Related Art Conventionally, in position detection of a motor, as shown in FIG. 7, a magnetic field from a magnet piece 21a provided on the outer peripheral surface of a rotor 21 of the motor is opposed to the outer peripheral surface of the rotor 21. Detecting with a magnetic head 22 or the like arranged at a position, amplifying an output signal from this magnetic head 22 with an amplifier 23, and obtaining a pulse signal having one cycle of one rotation of the rotor 21 as shown in FIG. Is done by.

[0003]

However, the above position detecting device has the following problems. That is, in the position detecting device, the magnet piece 21a and the magnetic head 2 are
2 is required, and the magnetic head 22 and the magnet piece 21a are required.
Must be newly installed for the position detection device, so
There is a problem that the number of parts increases and the cost increases.

Further, when a magnetic detector such as the magnetic head 22 is used, electric wiring is required on the substrate (printed circuit board), which complicates the work, and the magnetic detector is provided on the outer peripheral surface of the rotor magnet 21. There is a problem in that it is not possible to reduce the size of the board because the boards are arranged at opposite positions and a large space for electric wiring is required on the board.

Therefore, it is an object of the present invention to provide a position detecting device in which the number of parts is reduced and the cost is reduced, the manufacturing cost is reduced, and the size of a substrate can be reduced.

[0006]

In order to achieve the above-mentioned object, the position detecting device of the present invention has an N pole and an S pole of a driving magnetic pole.
Rotor magnets whose poles are alternately magnetized and rotate integrally with the rotating shaft, at least one magnetic pole for position detection of the same pole provided on the end face of the central portion of the drive magnetic pole, and this magnetic pole for position detection And a drive magnetic detector arranged at a position facing the means for simultaneously detecting the magnetic field of the drive magnetic pole and the magnetic field of the position detecting magnetic means, and amplifying an output signal from the drive magnetic detector. A linear amplifier, a drive magnetic detector signal differential amplifier for amplifying and logarithmically compressing the output signal from the drive magnetic detector, an output signal from the drive magnetic detector signal differential amplifier, and A differential amplifier that compares the output signal from the linear amplifier and a waveform shaping amplifier that waveform-shapes the output signal from the differential amplifier and uses the output signal as a position detection signal. There.

[0007]

According to the position detecting device in such means, the drive magnetic detector used in the motor is also used as the position detecting magnetic detector, and the magnetic detector and the magnet piece which have been used conventionally are used. In addition to working to reduce the number of parts and cost, it also works to reduce the manufacturing cost by eliminating the mounting of magnet pieces and the mounting of the magnetic detector on the board, and the space for the magnetic detector and its wiring space are eliminated, and the board is Work to miniaturize.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a motor including a position detection device showing a first embodiment of the present invention. The motor used in this embodiment is a three-phase brushless motor. In the figure, reference numeral 1 indicates a rotary shaft, and the rotary shaft 1 is rotatably supported by a circuit board 3 via a bearing 5. A rotor 2 which rotates integrally with the rotary shaft 1 is fixed to the rotary shaft 1, and an N-pole and an S-pole as shown in FIGS. 2 and 3 are formed on the inner peripheral surface of the rotor 2. Rotor magnets 2a that are magnetized alternately in the circumferential direction are arranged. The end face of the rotor magnet 2a is magnetized for position detection 2b as the magnetic means for position detection as shown in FIG. 3, and in this embodiment, it is formed in the central portion on the N pole. A circuit board 3 is disposed at a position facing the end surface of the rotor 2 and a Hall element 4 as a driving magnetic detector is disposed at a position on the circuit board 3 facing the position detecting magnetization 2b. It is provided. A drive IC 11 provided on the circuit board 3 is connected to each output terminal of the Hall element 4. This drive I
As shown in FIG. 2, C11 are respectively connected to the output terminals of the Hall element 4, and amplify the output signal from the Hall element 4 and logarithmically compress it. Connected to the differential amplifier 8 and the output terminals of these Hall signal differential amplifiers 8,
A motor drive circuit 6 for sending a drive current to a drive coil L arranged at a position opposite to the inner peripheral surface of the rotor magnet 2a in accordance with an output signal from the Hall signal differential amplifier 8.
And connected to one of the output terminals of the Hall element 4,
A linear amplifier 7 that amplifies the output signal from the Hall element 4, one end of the linear amplifier 7 at the output terminal of the linear amplifier 7, and the other end of the linear amplifier 7 at the output terminal of the differential Hall signal amplifier 8 downstream of the selected Hall element 4. A differential amplifier 9 which is connected to each other and compares the output signal of the linear amplifier 7 with the output signal of the differential amplifier 8 for Hall signals, and the output from the differential amplifier 9 which is connected to the output terminal of the differential amplifier 9. A waveform shaping amplifier 10 which shapes the waveform of the signal and uses the output signal as a position detection signal. 2, the Hall element 4 is drawn at a position facing the outer peripheral surface of the rotor magnet 2a and the coil L is drawn at a position outside the rotor magnet 2a in order to avoid complication of the drawing. As shown in FIG. 1, the Hall element 4 is arranged on the circuit board 3 at a position facing the position detecting magnetized 2b, and the coil L is arranged at a position facing the inner peripheral surface of the rotor magnet 2a.

Next, the operation of this position detecting device will be described. When a predetermined voltage is applied to the drive coil L, the rotor 2
Rotates and the rotor magnet 2a with respect to the Hall element 4 is rotated.
The N poles and the S poles alternately face each other, and a sine wave waveform is output from the Hall element 4 according to the direction of the magnetic field, but the rotor magnet 2a is magnetized for position detection 2b as described above. Therefore, a sine wave-like waveform having a pulse-shaped peak once per rotation shown in FIG. 4A is output.
This output signal is amplified by the Hall signal differential amplifier 8 and logarithmically compressed, converted into a peaked waveform shown in FIG. 4B, input to the motor drive circuit 6, and driven in accordance with these signals. The drive current is sent to the respective coils L to rotate the rotor 2. On the other hand, the sine wave-like output signal having a pulse-like peak once per rotation shown in FIG.
As shown in (c), the signal is amplified in its original shape and compared with the peaked output signal shown in FIG. 4 (b) in the differential amplifier 9. Then, the differential amplifier 9 outputs a waveform signal having a peak as shown in FIG. 4D, and the output signal is the waveform shaping amplifier 1.
The waveform is shaped by 0, and the pulse signal as shown in FIG. 4E is obtained as the position detection signal.
The waveform diagrams of FIGS. 4A to 4E respectively correspond to the points a, b, c, d, and e in FIG.

As described above, in this embodiment, the magnet piece which has been conventionally required is not required, and the Hall element 4 used for driving the brushless motor is also used as the magnetic detector for position detection. Therefore, the number of parts can be reduced and the cost can be reduced. Further, it is possible to eliminate the mounting of the magnet pieces and the mounting of the magnetic detector on the board, and further, it is possible to eliminate the space for the magnetic detector and the wiring space therefor, which makes it possible to reduce the manufacturing cost and downsize the substrate. ing.

FIG. 5 is a perspective view of a rotor magnet 2a showing a second embodiment of the present invention. The difference between the rotor magnet 2a of the second embodiment and that of the first embodiment is that
The point is that a protrusion 2c for position detection is formed in place of the position detection magnetized 2b as the position detection magnetic means provided on the end surface of the rotor magnet 2a. Even with this configuration, the Hall element 4 obtains a sinusoidal output signal having a pulse-like peak once per rotation, as shown in FIG. 4A, due to the change in the air gap with the protrusion 2c. Will be
It goes without saying that the same effect as the first embodiment can be obtained.

FIG. 6 is a top view of a rotor magnet 12a showing a third embodiment of the present invention. This third embodiment is an example of application to a plane-opposed motor, and since the shape of the rotor magnet 12a changes, the N and S poles of the rotor magnet 12a are magnetized accordingly.
The position detection magnetizing 12b is applied to the center of the end face in the vicinity of the outer peripheral surface of the N pole, as shown in FIG. 5, but the other main configuration is the same as that of the first embodiment. It goes without saying that the same effect as that of the first embodiment can be obtained even with the above configuration.

The invention made by the present inventor has been specifically described based on each embodiment, but the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say, for example, in the above embodiments, the position detecting magnetic means 2 is used.
Although b, 2c, and 12b are provided in the N pole, they may of course be in the S pole and may be in two or more locations.

Further, in each of the above-mentioned embodiments, the application example to the three-phase brushless motor is described.
It is also applicable to brushless motors other than the phase type.

Furthermore, in each of the above-mentioned embodiments, the application example to the brushless motor using the Hall element 4 as the driving magnetic detector is described, but the present invention uses the driving magnetic detector other than the Hall element. Of course, it can be applied to a brushless motor.

[0016]

As described above, according to the position detecting device of the present invention, the magnetic detector for driving used in the motor is also used as the magnetic detector for detecting the position. The detector and the magnet piece are not required, and the cost can be reduced. Also, the attachment of the magnet piece and the mounting of the magnetic detector on the substrate are eliminated, which reduces the manufacturing cost, and the space for the magnetic detector and its wiring space are also unnecessary. Therefore, the size of the substrate can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a motor including a position detection device showing a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram schematically showing FIG.

FIG. 3 is a perspective view of a rotor magnet shown in FIG.

FIG. 4 is a signal waveform diagram for explaining a circuit operation.

FIG. 5 is a fragmentary perspective view of a rotor magnet showing a second embodiment of the present invention.

FIG. 6 is a top view of a rotor magnet showing a third embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of a position detection device showing a conventional technique.

8 is a waveform diagram showing a position detection signal according to FIG. 7.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotating shaft 2a, 12a rotor magnets 2b, 2c, 12b position detecting magnetic means 4 driving magnetic detector (Hall element) 7 linear amplifier 8 driving magnetic detector signal differential amplifier 9 differential amplifier 10 waveform shaping amplifier

Claims (1)

[Claims] 1. A rotor magnet, in which N poles and S poles of a driving magnetic pole are alternately magnetized and rotates integrally with a rotating shaft, and at least one or more same poles provided on an end face of a central portion of the driving magnetic pole. Position detecting magnetic means, and a driving magnetic detector arranged at a position facing the position detecting magnetic means, for simultaneously detecting the magnetic field of the driving magnetic pole and the magnetic field of the position detecting magnetic means, A linear amplifier for amplifying an output signal from the driving magnetic detector, a differential amplifier for driving magnetic detector signal for amplifying and logarithmically compressing the output signal from the driving magnetic detector, and the driving magnetic detector A differential amplifier that compares the output signal from the detector signal differential amplifier with the output signal from the linear amplifier, and the output signal from this differential amplifier is waveform-shaped, and the output signal is used as a position detection signal. Waveform Position detection device consisting of shaping amplifier.