JPH0562297A - Motor brake control device - Google Patents

Abstract

PURPOSE:To perform an optimum brake control by scrupulously controlling the braking action in accordance with the motor speed reduction condition. CONSTITUTION:Assume that a DC motor section 20 changes its forward rotational speed from five times of standard speed to the standard speed then, the deviation amount data, which is inputted to a brake judgement processing circuit 14, becomes a negative number indicating a speed reduction. When this negative number becomes lower than -N, a brake decision processing circuit 24 reverses a forward/reversal rotation switching signal 500 and applies a brake to the DC motor section 20. This braking operation continues until the revolving speed of the motor section 20 becomes approximately the standard speed and furthermore, the speed control data outputted from the circuit 24, i.e., the brake voltage outputted from a D/A converter 25 varies in accordance with the rotational speed of the motor section 20. When the speed of the motor section 20 becomes the target speed, the circuit 24 puts the signal 500 back to the original and generates a speed control data based on the deviation data inputted from a frequency discriminator 22 through a gain phase compensator 23, outputted to the D/A converter so as to maintain the speed of the motor section 20 at the standard revolving speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor brake control device for braking a DC motor used in a home video tape recorder (VTR).

[0002]

2. Description of the Related Art Conventionally, in a domestic VTR, a DC motor called a capstan motor has been used to convey a magnetic tape as a recording medium. This DC motor can perform forward rotation and reverse rotation so that fast-forward reproduction and rewind reproduction can be performed quickly. In the VTR, when shifting from the fast-forward playback or rewinding playback mode to the normal playback mode, from the viewpoint of improving the speed of the shifting operation, the motor is braked and decelerated to change from normal rotation to reverse rotation and reverse rotation. The operation speed for switching to normal rotation is improved. That is, when the motor is rotating in the forward direction, a constant braking voltage that rotates the motor in the reverse direction is applied to brake the motor, or when the motor is rotating in the reverse direction, a constant braking voltage that rotates the motor in the forward direction. Then, the operation of applying a brake to this motor is performed.

By the way, there are a method of setting the brake release timing after the motor is braked as described above after a certain period of time, and a method of dynamically observing the deceleration state of the motor. In the former method, since the brake voltage is constant, the brake must be set weakly so as not to decelerate too much, and the brake time must also be set short so that the motor can be decelerated quickly. From the perspective, it is not enough. In the latter method, an FG signal provided for controlling the speed of the motor is measured, and when the cycle of the FG signal reaches a preset target cycle, the brake of the motor is released. Therefore, the braking operation of the motor can be made faster than the former method.

FIG. 3 is a block diagram showing a conventional example of a brake control device for a motor adopting the latter method. A portion indicated by a dotted line 1 in the drawing is a DC motor section showing a DC motor such as a capstan motor. Reference numeral 11 denotes a rotor magnet which constitutes a DC motor, and the rotating magnetic field generated by the armature 13 causes the rotor magnet 11 to rotate. The rotation position of the rotor magnet 11 is the Hall sensor 1
2 and the position information is detected by the position detection circuit 18
Entered in. The position detection circuit 18 uses the switching transistor group 17 based on the position information input from the hall sensor 12 and the speed information input from the amplifier 21.
Is switched to generate a rotating magnetic field that causes the armature 13 to rotate in an arbitrary direction at an arbitrary speed.

The pattern coil 14 is the rotor magnet 1
An FG signal proportional to the rotation of 1 is generated, the amplifier 15 amplifies this FG signal, the Schmitt circuit 16 shapes the waveform of the amplified FG signal, and the speed control device 2
Is output to the speed detector 3. The speed control device 2 compares the input FG signal with the target speed signal and generates a speed control voltage 100 so as to match the frequency of the FG signal with that of the target speed signal. Output to. During normal operation, the switch 7 is switched to the terminal a side, so that the control voltage 100 is input to the inverting input terminal of the amplifier 20. Since the control reference bias voltage V _f is input to the non-inverting input terminal of the amplifier 20, the difference between the control voltage 100 and the bias voltage V _f is the amplifier 2.
1 is input to the inverting input terminal. Since the voltage corresponding to the current flowing through the switching transistor group 17 is input to the non-inverting input terminal of the amplifier 21, the difference between the difference voltage and this voltage is input to the phase detection circuit 18 as speed control information of the rotor magnet 11. To be done. As a result, the rotor magnet 11 rotates at the target speed.

When the operation mode for breaking the DC motor is entered, the brake control circuit 6 switches the switch 7 to the terminal b side and supplies the brake voltage V _B to the amplifier 20. Together with the forward / reverse rotation switching signal 200
Is output to the position detection circuit 18. As a result, the position detection circuit 18 controls the switching transistor group 17 to reverse the rotation direction of the rotating magnetic field generated by the armature 13 and brake the rotor magnet 11 with a constant force. At this time, the speed detector 3 inputs the FG signal 100 output from the Schmitt circuit 16 to detect the speed of the rotor magnet 11, and outputs the detection signal to the comparator 4. Since the brake release data is input from the brake release data setting circuit 5 to the comparator 4, this data is compared with the speed data input from the speed detector 3, and if the two match, a match signal is output. Is output to the brake control circuit 6. When the coincidence signal is input, the brake control circuit 6 switches the switch 7 to the terminal a side and restores the normal / reverse rotation switching signal 200. As a result, the braking operation on the rotor magnet 11 is released, and the normal speed control mode is restored.

In the conventional brake control apparatus as described above, the DC voltage applied to the DC motor unit 1 is constant, so that the DC voltage is applied to the DC motor unit 1 at the start time and the end time of the brake. It will apply the same strength to the brakes. Therefore, there is a risk that the DC motor will be decelerated too much or reversed. Therefore, the brake voltage must be set lower than the maximum, and the brake release operation must be set earlier, which makes it difficult to perform optimum brake control. ..

[0008]

As described above, the motor is decelerated by applying a constant brake voltage for rotating the motor in the direction opposite to the rotation direction of the motor, and the motor is decelerated. Is stopped at a predetermined speed, the application of the brake voltage is stopped to cancel the brake operation.
In the brake control device, since the brake voltage is constant, the motor may slow down too much or may reverse. Therefore, the brake voltage should be set lower than the maximum value. However, there is a drawback that it is difficult to perform optimum brake control because the brake release operation must be set earlier.

In view of the above, the present invention eliminates the above-mentioned drawbacks, and it is possible to perform optimum brake control by finely controlling the strength of the brake according to the deceleration state of the motor. An object is to provide a table brake control device.

[0010]

The motor brake control apparatus of the present invention obtains the deviation amount between the data proportional to the rotation speed of the motor and the target speed data, and rotates the motor so that the deviation amount becomes substantially zero. In a control system that creates a speed control voltage for obtaining a speed and applies the speed control voltage to the motor to control the rotation speed of the motor, the motor is in a deceleration state based on the deviation amount. It comprises a determination means for determining and a control means for reversing the rotation direction of the motor when the determination means determines that the motor is decelerating.

[0011]

In the motor brake control device of the present invention, the determining means determines from the deviation amount that the motor is in the decelerating state. The control means reverses the rotation direction of the motor when the determination means determines that the motor is decelerating. As a result, the motor is braked according to its deceleration state.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the brake control device of the present invention. Reference numeral 20 is a DC motor unit (details are the same as in FIG. 3) for running a magnetic tape such as a VTR, 21
Is a frequency dividing circuit for dividing the FG signal 300 corresponding to the rotation speed of the DC motor unit 20, and 22 is a deviation amount from the target speed data 400 by counting the divided FG signal with a reference clock. Is a frequency discriminator for obtaining a gain phase compensator for compensating the gain and phase of the control system so that the control system is stable,
Reference numeral 24 indicates the normal rotation of the DC motor unit 20 based on the deviation amount.
A brake determination processing circuit that outputs a reverse rotation switching signal 500 and control data 600 that controls the rotation speed of the DC motor unit 20, and 25 is control data input from the brake determination processing circuit 24. Is an analog voltage and outputs it to the DC motor unit 20.

Next, the operation of this embodiment will be described. When the motor is rotating, the DC motor unit 20 outputs an FG signal 300 proportional to its speed. This FG signal 3
00 is frequency-divided by the frequency dividing circuit 21 to generate a frequency discriminator 22.
Entered in. The frequency discriminator 22 inputs the frequency division FG
After counting the signals with the reference clock 50, the amount of deviation from the target speed data 400 is calculated, and this is calculated as the gain phase compensator 23.
Output to. The gain phase compensator 23 compensates the gain and phase of the input deviation amount data so that the control system is stable,
This is output to the brake determination processing circuit 24. The brake determination processing circuit 24 outputs a forward / reverse rotation switching signal 500 that determines the rotation direction of the DC motor unit 20 and creates speed control data 600 that makes the input deviation amount data zero. To the D / A converter 25. The D / A converter 25 converts the input speed data 600 into a corresponding analog voltage and supplies this to the DC motor unit 20 as a motor control voltage. Thereby, the DC motor unit 20 is controlled to rotate at the speed specified by the target speed data 400.

FIG. 2 shows the above-mentioned brake judgment processing circuit 24.
FIG. 7 is a diagram showing the input / output characteristics and output state of a forward / reverse rotation switching signal 500. In (A), the horizontal axis represents the deviation amount input to the brake determination processing circuit, and the vertical axis represents the speed control data of the motor unit output from the brake determination processing circuit 24. There is. However, if the deviation amount data is positive, it indicates acceleration, and if it is negative, it indicates a deceleration command. That is, the deviation amount data when the motor unit 1 is under speed control is in the vicinity of φ in the figure. The characteristic indicated by the dotted line shows the input / output characteristic of this type of conventional control system which does not have a brake judgment processing function.
Dynamic range of the A / A converter 25 (in this case, 12
It has only the limiter characteristic that limits it within (bit).
The characteristic indicated by the solid line is the input / output characteristic of the brake determination processing circuit 24 shown in FIG. 1, and it corresponds to the negative input deviation amount data (deceleration state) below a certain value (-N). The characteristic of inverting the sign of the speed control data output from the key determination processing circuit 24. Here, the constant value -N secures a margin for preventing the brake operation in the stable state (servo lock state) of the control system shown in FIG. Input deviation amount at
It is set a little larger than the fluctuation amount of the data. (B) shows the forward / reverse rotation switching signal 500 output from the brake determination processing circuit 24, and shows the conditions under which the input / output characteristics of the brake determination processing circuit 24 shown in FIG. Under the same condition, the output state of the normal / reverse rotation switching signal 500 is reversed.

Here, for example, it is assumed that the DC motor unit 20 is rotated in the forward direction at 5 times the standard speed, and the operating mode is changed to 1 time. At this time, the deviation amount data input to the brake determination processing circuit 24 is a negative number indicating deceleration. When this negative number becomes less than or equal to −N in FIG.
The brake determination processing circuit 24 inverts the forward / reverse rotation switching signal 500 as shown in FIG.
Break 0. This breaking operation continues until the number of rotations of the DC motor unit 20 becomes almost 1 time, and
As shown in FIG. 2 (A), the speed control data output from the brake determination processing circuit 24, that is, the brake voltage output from the D / A converter 25 in this case is the DC motor unit 20. Changes according to the rotation speed of. That is, when the rotation speed of the DC motor unit 20 is high, the brake voltage is large, and when the rotation speed of the motor is decelerated by the brake operation to approach the target speed, the brake voltage is changed. To be smaller
It is controlled by the brake determination processing circuit 24. In this way, when the DC motor unit 20 reaches the target speed, which is the operation mode of 1 time in this case, the brake determination processing circuit 24 restores the normal / reverse rotation switching signal 500 to the original state, and the frequency discriminator 22 outputs it. Velocity control data is created based on the deviation data input via the gain / phase compensator 23, and this is D / A.
It outputs to the converter 25, and returns to the normal speed control operation for maintaining the DC motor unit 20 at the rotation speed of 1 time.

According to this embodiment, for example, the DC motor unit 2
By changing the operation mode of 0 from 5 times to 1 time, the DC motor unit 2 can be used without setting a special brake mode.
0 can be braked, and the brake voltage at this time, that is, the motor control voltage, has a characteristic of gradually decreasing in proportion to the deceleration of the DC motor unit 20, so that the motor unit 20 is decelerated too much. Alternatively, problems such as reverse rotation can be avoided, and the DC motor unit 2 is the fastest.
0 can be braked to control the target speed or stop condition. Therefore, the VTR fast-forward reproduction or rewinding reproduction mode can be quickly and smoothly switched to the normal reproduction mode. Further, when the motor unit 20 is shifted from the normal stop state to the reproduction state, even if the acceleration state of the motor unit 20 causes an overshoot, the brake operation is automatically activated to obtain a good response characteristic. ..

[0017]

As described above, the motor tray of the present invention is used.
According to the key control device, it is possible to perform the optimum brake control by finely controlling the strength of the brake according to the deceleration state of the motor.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a brake control device for a motor of the present invention.

FIG. 2 is a characteristic diagram illustrating operating characteristics of the brake control device shown in FIG.

FIG. 3 is a block diagram showing an example of a conventional motor rake control device.

[Explanation of symbols]

20 ... DC motor part 21 ... Dividing circuit 22 ... Frequency discriminator 23 ... Gain phase compensator 24 ... Break judgment processing circuit 25 ... D / A converter

Claims (1)

[Claims] 1. A speed control voltage for obtaining a rotation speed of the motor such that the deviation amount between the data proportional to the rotation speed of the motor and the target speed data is obtained, and the deviation amount becomes substantially zero, In a control system for controlling the rotation speed of the motor by applying the speed control voltage to the motor, there is provided a judging means for judging that the motor is in a decelerating state from the deviation amount, and the judging means And a control unit for reversing the rotation direction of the motor when it is determined that the motor brake is decelerating.