JPS6323754B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a reel motor in a VTR, for example.
This invention relates to motor control circuits for drum motors, capstan motors, etc.

In the above-mentioned VTR motor control, for example, when starting, conventionally, electric power was simply applied to each motor and the motors were rotated. However, when the motor rotates, power consumption is greatest during acceleration such as during startup. Therefore, if each motor is started at the same time as described above, the overall power consumption will become extremely large.

In addition, in motor control as mentioned above, so-called
When performing AFC, conventional AFC circuits cannot control the rotation speed at one or several predetermined points.

In view of these points, the present invention uses a microprocessor to perform various controls such as reducing power consumption during startup as described above and performing AFC at any speed.

However, when such control is performed by a microprocessor, precise control cannot be performed because the microprocessor has a slow signal processing speed.

The present invention has been made taking such points into consideration. An embodiment of the present invention will be described below with reference to the drawings.

First, FIG. 1 shows an example of the basic configuration of the present invention. In the figure, 1 is a microprocessor, and this microprocessor 1 includes a central processing circuit (CPU).
A read-only memory (ROM) and a random access memory (RAM) are built-in, and these are connected by a data bus, a control bus, and an address bus. When the clock signal from the oscillator 2 is supplied, the CPU processes the data stored in the RAM according to the program written in the ROM.

Furthermore, a bus 3 including a data bus, a control bus, and an address bus is led out, and various circuits are connected to this bus.

Reference numeral 4 is, for example, a drum motor, and the motor 4 is provided with a frequency generator (FG) 5 as a frequency generator for detecting rotational speed and a pulse generator (PG) 6 for detecting rotational phase. The signal from the pulse generator 6 is supplied to a phase comparator 7, and the clock signal from the oscillator 2 is supplied to a frequency divider 8, which serves as a reference signal generation circuit, to form, for example, a vertical period reference signal. This reference signal is supplied to the phase comparator 7. This comparison output is then supplied to bus 3.

Further, the signal from the frequency generator 5 is supplied to a frequency measuring circuit 9 to measure the frequency, and this measured value is supplied to the bus 3.

Furthermore, a signal from the frequency generator 5 is supplied to the AFC circuit 10. Further, the signal on the bus 3 is supplied to the DA conversion circuit 11, and the signal from this DA conversion circuit 11 is supplied to the AFC circuit 10.

The signal from this AFC circuit 10 is sent to the switch 12.
is supplied to one contact of the DA converter circuit 11.
is applied to the other contact of switch 12. Furthermore, the signal from bus 3 is applied to parallel output port 13, from which one bit is applied to the control terminal of switch 12.

The signal taken out from the switch 12 is then supplied to the motor 4.

Furthermore, from the system control circuit 14
A signal indicating the operating state of the VTR is supplied to the bus 3.

In this configuration, the signal from the phase comparator 7 and the signal from the frequency measurement circuit 9 are supplied to the microprocessor 1 via the bus 3. When the signal from the system control circuit 14 is in a predetermined recording/reproduction mode, a digital signal corresponding to the APC signal is formed in the microprocessor 1, and this signal is supplied to the DA conversion circuit 11. A signal from the output port 13 connects the switch 12 to the AFC circuit side as shown.

Therefore, in this configuration, in a predetermined recording/reproducing mode, the signal from the microprocessor 1
While APC is performed, AFC is performed using analog signals as they are. Therefore, AFC is performed without time delay such as during signal processing, and precise control can be performed.

Further, at the time of startup, a signal indicating the time of startup is supplied from the system control circuit 14. At this time, the switch 12 is connected to the DA conversion circuit 11 side by the signal from the output port 13, contrary to the illustration, and the signal that enables the microprocessor 1 to obtain the target startup characteristics is connected to the DA conversion circuit. It is supplied to the circuit 11.

However, when considering the startup for normal recording and playback, it is necessary to start the reel motor in synchronization with the rise of the capstan to keep the tape tension constant, and also to start the drum motor and perform fast forwarding and winding. If the return operation is performed at the same time, the power consumption will instantly increase considerably. Therefore, a circuit from the motor 4 to the switch 12 described above is provided for each reel motor, drum motor, and capstan motor, and the signals supplied to each DA conversion circuit are adjusted.

That is, if the reel motor is started as shown in FIG. 2A, the power consumption at this time will be as shown in FIG. 2B. If the tram motor and capstan motor are started at the same time, the motors will start up as shown by the solid line in Figure 2C, and the power consumption of this motor will be as shown in the solid line in Figure 2D. The total power consumption becomes as shown by the solid line in FIG. 2E. On the other hand, if the microprocessor 1 controls signals to start the motor as shown in the broken line in Figure 2C, the power consumption of this motor will be as shown in the broken line in Figure 2D, and the overall power consumption will be as shown in the broken line in Figure 2D. Since the power consumption becomes as shown by the broken line in FIG. 2E, the maximum power consumption at startup can be reduced.

Furthermore, for example, in a capstan motor, 2
Even when playing at variable speeds such as double speed, triple speed, 1/2 speed, etc., AFC can be performed at any speed by performing AFC through the microprocessor 1. Note that in controlling the capstan motor, the reproduced CTL signal from the CTL reproducing head is used instead of the output of the pulse generator 6.

The motor is controlled in this way, and according to the present invention, various controls can be performed by using a microprocessor, and AFC is performed using analog signals in a predetermined recording/playback mode, so precise control can be performed. It can be carried out. Note that during variable-speed playback at startup, the quality of the playback signal is not much of a problem, so the accuracy of AFC may be low.

Furthermore, since the voltage, current, power consumption, etc. of the motor can be freely controlled, the motor's capacity can be utilized to the maximum within its rating. Furthermore, by performing appropriate control, the start-up time until stable operation can be shortened.

Further, FIG. 3 shows a specific circuit example when the present invention is used to control a drum motor. In the figure, the outputs of the pulse generator 6 and the frequency generator 5 are passed through comparators 21 and 22, respectively, to a phase comparator 7,
The signal is supplied to a variable delay line 23 and a sample pulse forming circuit 24, which constitute the frequency measurement circuit 9 and the AFC circuit 10. Further, the outputs of the phase comparator 7 and the frequency measuring circuit 9 are respectively supplied to counters 25 and 26 constituting an interface circuit, and
A clock signal from the oscillator 2 is supplied to these counters 25 and 26, and this count value is sent to the bus 3.
is supplied to

Also, the bus 3 signal passes through the latch circuit 27.
The signal is supplied to the DA conversion circuit 11. The signal from this DA conversion circuit 11 is supplied to the control terminal of the variable delay line 23. The signal from this variable delay line 23 is supplied to a sample hold circuit 29 through a trapezoidal wave generating circuit 28. Further, pulses from the sample pulse forming circuit 24 are supplied to a sample hold circuit 29. The sampled and held signal is then supplied to the switch 12 through the buffer circuit 30.

Further, the control signal from the decoder 31 controls the parallel output port 13 to obtain a control signal to the switch 12, and the signal from the decoder 31 controls each interface circuit (counter 25, 26).
Latch circuit 27 and system control circuit 1
It is supplied to a control terminal such as No. 4.

A signal from the switch 12 is then supplied to the motor 4 through a driving power amplifier 32.

In this way, a drum motor control circuit is formed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the basic configuration of the present invention, FIG. 2 is a diagram for explaining the same, and FIG. 3 is a configuration diagram of an example in which the present invention is applied to a drum motor. 1 is a microprocessor, 4 is a motor, 5 is a frequency generator, 6 is a pulse generator, 7 is a phase comparison circuit, 9 is a frequency measurement circuit, 10 is an AFC circuit, 1
1 is a DA conversion circuit.

Claims (1)

[Claims] 1 A frequency generator that generates a frequency signal according to the rotational speed of the motor, a pulse generator that generates a pulse signal according to the rotational phase of the motor, and a pulse generator that instructs the operation mode of the motor and uses the motor as a driving force. a system control circuit for instructing an operating mode of a system to be used, and controlling the rotation of the motor in accordance with the frequency signal and the pulse signal based on instructions from the system control circuit; a reference signal generation circuit that generates a signal serving as a phase reference; a phase comparison circuit that compares the phase of the output signal of the reference signal generation circuit with the pulse signal; and a frequency measurement circuit that measures the frequency of the frequency signal. , a microprocessor that generates at least phase control data, frequency control data, and mode control data for controlling the rotation of the motor according to the system control circuit output, the phase comparison circuit output, and the frequency measurement circuit output; and the above phase control data and the above frequency control data generated by the above microprocessor.
A DA conversion circuit that performs DA conversion, and a DA conversion circuit that receives the frequency signal output from the frequency signal generator and forms a signal that controls the rotation speed of the motor so that the frequency of this frequency signal becomes a predetermined value.
AFC that combines the DA conversion signal of the phase control data output from the conversion circuit with the signal that controls the rotation speed.
DA of the frequency control data of the output signal of the above AFC circuit and the output signal of the above DA conversion circuit.
A motor control circuit comprising: a switch circuit that selects either one of the conversion signal and the conversion signal according to mode control data output from the microprocessor and supplies the selected signal to the motor.