JPS639273Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a capstan motor of a magnetic recording/reproducing device, for example, and particularly corrects torque ripple.

For example, to rotate a capstan motor at a constant speed, a servo system using so-called AFC and APC is often used. In Fig. 1, a frequency generator (FG) 2 and a pulse generator (PG) 3 are provided in association with a motor 1. A signal from this FG 2 is supplied to a frequency-to-voltage converter 5 through an amplifier 4, and the resulting voltage is output by a combiner 6 to a terminal 7.
The signal from PG3 is supplied to the combiner 6 through the APC circuit 9.

In this way, constant speed servo of the motor is performed.

However, in the case of this device, the frequency characteristics of the device do not extend to a sufficiently high range, and corrections are not made for high frequency rotational irregularities such as uneven magnetization of the magnet and so-called torque ripple that occurs between coils. It won't happen. Note that torque ripple exists uniquely in each motor, and the same torque ripple is repeatedly generated for each rotation of the motor.

In response to this problem, the following device has been proposed which is capable of correcting the above-mentioned torque ripple.

In FIG. 2, a constant voltage from terminal 7 is supplied directly to motor 1 through amplifier 8. In FIG. Here, the motor 1 normally rotates at a constant speed. However, in reality, the rotational speed fluctuates due to torque ripple. Therefore, by extracting this rotational speed by FG2 and supplying this signal to the frequency-voltage converter 12 through the amplifier 11, the converter 12 outputs a signal that responds to the rotational unevenness at each position of one rotation of the motor 1 caused by torque ripple. voltage is taken out. This voltage is supplied to the data terminal of memory device 13.

On the other hand, the signal from the amplifier 11 is supplied to the counter 14, and the signal from PG3 is supplied to the reset terminal of the counter 14. As a result, the counter 14
Numerical values corresponding to each position of one rotation of the motor 1 are taken out from . This numerical value is supplied to the address terminal of the memory device 13 through the decoder 15.

Therefore, in this device, the amount of torque ripple generated at each position during one rotation of the motor 1 is stored at an address corresponding to each position in the memory device 13, respectively. Note that the torque ripple can also be detected by other methods, for example, by measuring changes in the current flowing through the motor 1.

In order to rotate this motor 1 at a constant speed, it is done as shown in FIG.

In the figure, part of the signal supplied from FG2 to the frequency-voltage converter 5 through the amplifier 4 is supplied to the counter 14, and part of the signal supplied from PG3 to the APC circuit 9 is supplied to the reset terminal of the counter 14. be done. Furthermore, the value of this counter 14 is supplied to the address terminal of the memory device 13 through a decoder 15. The signal from the data terminal of the memory device 13 is then supplied to the synthesizer 6.

Therefore, in this device, the amount of torque ripple stored in the memory device 13 is sequentially output corresponding to each rotational position of the motor 1, and this signal is supplied to the synthesizer 6 to correct the torque ripple.

Torque ripple is corrected in this way. According to this device, the amount and position of torque ripple generated are stored in the storage means, and a signal from the storage means is supplied to the drive circuit during driving to correct the torque ripple. Since this is done, even high-frequency torque ripple can be corrected satisfactorily.

Therefore, when this device is applied to, for example, a capstan motor of a magnetic recording/reproducing device, the performance of wow, flutter, jitter, etc. can be greatly improved. In this case, the torque ripple of the entire tape drive system, such as the capstan shaft, may be detected and stored.

Furthermore, according to this device, since a motor with low characteristics can be used, the overall price can be reduced.

However, this device requires a counter and a memory device for detecting and storing the amount of torque ripple generated and the device that generates it, resulting in a complicated and large-scale configuration.

In view of these points, the present invention is intended to enable good torque ripple correction with a simple configuration.

In FIG. 4, a ferrite ring 21 is provided in association with the motor 1, and a head 22 is provided adjacent to the ferrite ring 21 to constitute an FG 2. By supplying a constant voltage from the terminal 7 to the motor 1 through the amplifier 8, a signal corresponding to the uneven rotation of the motor 1 is extracted from the head 22. By supplying this signal to the frequency-voltage converter 12 through the amplifier 11,
A voltage is generated according to rotational unevenness. This voltage then passes through the amplifier 23 to the ferrite ring 21.
The magnet is supplied to a head 24 provided opposite the edge of the magnet, and magnetization is performed according to the voltage.

Therefore, in this device, the torque ripple of one revolution of the motor 1 is recorded in one revolution around the edge of the ferrite ring 21.

Furthermore, when the motor 1 is driven, it is operated as shown in FIG.

In the figure, a magnetic flux responsive head 25 is provided opposite the edge of the ferrite ring 21, and a signal from this head 25 is supplied through an amplifier 26 to a combiner 27 where it is combined into a driving voltage.

Therefore, in this device as well, the torque ripple corresponding to each rotational position of the motor 1 is read out by the head 25, and is combined with the drive voltage to correct the torque ripple.

In this case, a ferrite ring is used as the storage means, eliminating the need for a counter or memory device, allowing the device to be realized with an extremely simple configuration.

By forming the portion surrounded by a broken line in FIG. 5 integrally with the motor 1, this device can be handled in exactly the same way as a conventional motor alone.

Thus, according to the present invention, torque ripple can be corrected satisfactorily with an extremely simple configuration.

[Brief explanation of the drawing]

Figures 1 to 3 are configuration diagrams of conventional equipment;
FIG. 5 is a configuration diagram of an example of the present invention. 12 is a frequency-voltage converter, 21 is a ferrite ring, and 22, 24, and 25 are heads.

Claims (1)

[Scope of utility model registration request] A drive circuit that drives the motor, a rotating body with magnetism that rotates integrally with the rotating shaft of the motor, and a magnetic rotating body that detects a signal corresponding to the torque ripple of the motor and sends the detection output to the outer periphery of the rotating body. and means for reproducing the signal recorded on the outer peripheral portion during driving and supplying it to the drive circuit to correct the torque ripple.