JPS63148879A - Parking brake device - Google Patents

Abstract

PURPOSE:To improve a high-speed response characteristic, by increasing the frequency of a bias signal higher than the frequency of a reel motor. CONSTITUTION:A tape reel 12 around which a magnetic tape is wound is set rotatably free with a reel motor 1, to the rotating shaft of which a rotating plate 13 is installed to rotate integrally. On the outside circumference of the rotating plate 13 magnetic patterns are provided at specified intervals, of which the flux change is detected with a pair of magnetic sensors 2a and 2b respectively and sent to a rotating angle detector 3 to generate the voltage S2 on a predetermined level. Furthermore, a reference signal generator 4 and a comparator 5 are provided, with which an error signal S4 is generated to drive and control the reel motor 1 with a motor driver 9 through a switch 8 along with a bias signal S5 from a bias generator 6 with an adder. As to the bias signal S5, the frequency signal sufficiently larger in frequency than the response frequency of the reel motor 1 is used.

Description

TECHNICAL FIELD The present invention relates to a parking brake device, and more particularly to a parking brake device for a reel motor of a magnetic recording/reproducing device using magnetic tape.

A magnetic recording/reproducing apparatus using a U1 ball magnetic tape has an operation of moving the tape to a specific address on the tape and then waiting at that specific address position until the next start command is given. In such a start standby state, there are two methods: using a tape tension servo function to balance the tensions in the tape feeding direction and the tape winding direction to keep the tape stationary, or applying a parking brake to the reel motor to stop the reel. There is a method of reducing the power of the motor and keeping it stationary.

In a magnetic recording/reproducing device using a rotating head, in the case of the former method, that is, a method in which the tape is brought to a standstill by balancing the tape tensioner, the rotating head and the tape are in contact with each other in the start position, so this method is The latter method, which applies the parking brake, is usually used only for special applications.

The parking brake device for applying the parking brake generally uses a system in which the brake belt is driven by a plunger solenoid, etc., which causes wear on the moving parts, slow operation speed, and There are drawbacks such as variations in characteristics. Furthermore, this method requires a complicated mechanism, which results in high cost, and furthermore, it has the drawback of requiring maintenance costs in order to maintain reliability.

Purpose of the invention Therefore, the present invention was made to solve the above-mentioned drawbacks of the conventional ones, and its purpose is to:
To provide a parking brake device which has a high operating speed and has no variation in characteristics.

Structure of the Invention The parking brake device according to the present invention includes a rotation angle detection means for detecting the rotation angle of the motor in response to a parking pre-key-on command and generating a detection signal corresponding to the rotation angle, and a reference angle at which the motor should be stopped. a comparison means for generating an error signal corresponding to a difference between a reference signal corresponding to the detection signal and the detection signal; a bias means for generating a bias signal having a frequency sufficiently larger than the response frequency of the motor; and a bias signal for generating the error signal. and the bias signal to obtain a drive signal for the motor.

Example Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a block diagram of an embodiment of the invention.

In the figure, a tape reel 12 on which a magnetic tape 11 is wound is rotatable by a reel motor 1, and a rotating plate 13 is attached to the rotating shaft of the reel motor 1. The rotating plate 13 is also configured to rotate.

On the outer periphery of this rotary plate 13, there are magnetic patterns provided at regular intervals, for example, and changes in magnetic flux that occur in the vicinity of this rotary plate 13 due to the rotation of these magnetic patterns are reduced to 1.
The pair of magnetic sensors 2a and 2b respectively detect the rotation signal 3.
1a, 311).

The rotation angle detector 3 receives rotation signals 31a and 31b from the pair of sensors 2a and 2b and generates a voltage S2 at a level corresponding to the angle at which the reel motor 1 rotates. The external signal S8 is a parking brake on command signal for the parking motor 1, and in response to this parking brake on command signal S8, the rotation angle detector 3 starts a rotation angle detection operation.

On the other hand, a reference signal generator 4 is provided, which generates a voltage S3 at a level corresponding to the stop position (stop rotation angle) at which the reel motor 1 is to be stopped, and this voltage level S3 is set in advance. It is assumed that there is

The comparator 5 compares the detection signal S2 and the reference signal S3 and generates an error signal S4 which is the difference between the two signals.
This error signal S4 becomes the input of the adder 7. A bias signal S5 from the bias generator 6 is used as the other input to the adder 7, and a signal having a frequency sufficiently higher than the response frequency of the reel motor 1 is used as the bias signal S5. The output S6 of the adder 7 is supplied to the motor driver 9 via the switch 8 and becomes a drive signal S7, which becomes a drive control signal for the reel motor 1.

A control signal S9 from the reel motor control section 10 is applied to the other input of the switch 8, and during normal reel motor operation other than when the parking brake is applied, the switch 8 receives this control signal S9 as an input to the motor driver 9. The selection operation is performed to control the playback of the tape 11, fast forwarding, two rewinding operations, etc.

When the parking brake of the reel motor 1 is turned on, the switch 8 operates to select the addition output S6 of the adder 7, and the rotation angle detector 3 starts operating. Therefore, a closed loop servo system for the reel motor 1 is formed, and the reel motor 1 operates to stop rotating at the stop position corresponding to the reference signal S3.

That is, in response to generation of the parking brake on command S8, the rotation angle of the reel motor 1 is detected by the sensors 1a and 1b, and the rotation angle detector 3 generates a detection signal S2 of a level corresponding to this rotation angle. The reel motor 1 is driven depending on the magnitude of the difference (83-32') between this detection signal S2 and the reference signal S3, and this difference (83-82')
It will operate as a closed-loop servo such that is zero.

Therefore, the reel motor 1 is moved to the preset stop position.
will rotate and stop, but the above difference (S3-32
) approaches zero, the driving force of the reel motor 1 also approaches zero, the above-mentioned servo system becomes open, and no braking force can be applied to the reel motor 1.

Therefore, in order to prevent such a phenomenon, it is conceivable to provide the comparator 5 as an error generating means with an excessive loop gain. However, with this method, loop hunting occurs around the point where the error signal (83-82) becomes zero.

Therefore, by generating the bias signal S5 by the bias generator 6 and adding it to the error signal (33-82), even if this error signal (33-82) becomes zero, this bias signal S5 can be applied to the reel motor 1. If the bias signal S5 is applied as a drive signal, positive and negative torques are always applied alternately in accordance with the positive and negative levels of the bias signal S5. Here, if the frequency of the bias signal S5 is set to be sufficiently higher than the response frequency of the reel motor 1, the motor torque generated by this bias signal S5 will be absorbed by the inertia of the reel motor system, and the motor 1 will rotate. Instead, it acts as a braking force. Due to this binding and application of the bias signal S5, the servo system always operates in a closed loop without becoming an open loop, and it becomes possible to generate a barking brake force.

As this bias signal S5, the reel motor 1 is
In the case of a frequency response characteristic of about H2, 1KHz to several KH
It is sufficient to use a signal having a frequency of z.

Although the above embodiment has been described as a parking brake device for a tape reel motor of a magnetic recording/reproducing device using magnetic tape, it is obvious that the parking brake device may be used for a motor of another device.

Effects of the Invention As described above, according to the present invention, the parking brake is applied electronically, and therefore no mechanical parts are required, so there is no wear or deterioration of parts and high-speed response characteristics are achieved. Moreover, it has the effect of being inexpensive. It is particularly suitable for use in video tape recorders that frequently perform start-stop operations.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. Explanation of symbols of main parts 1... Reel motor 3... Rotation angle detector 4... Reference signal generator 5... Comparator

Claims (1)

[Claims] A parking brake device for a motor, comprising a rotation angle detection means for detecting a rotation angle of the motor in response to a parking brake on command and generating a detection signal corresponding to the rotation angle, and a reference angle corresponding to a reference angle at which the motor should be stopped. comparing means for generating an error signal corresponding to the difference between the reference signal and the detection signal; bias means for generating a bias signal having a frequency sufficiently larger than the response frequency of the motor; A parking brake device comprising: an adding means for adding a bias signal to a drive signal for the motor.