KR940006555B1 - Capstan motor driving circuit - Google Patents

Abstract

The circuit detects a phase of counter electro motive force for 3 phase motor in stead of a hall device, reduces a design burden to wire-noise and cost-down, and stably drives 3 phase motor by adjustment of motor coil currents. The circuit includes a predrive unit (60), a motor drive unit (70), a 3 phase motor (80),a magnetic resisance device (40), a counter electromotive force sensor (140) which senses a counter electro motive force from coils (81-83) of 3 phase motor (80), a zero sensor (150), a latch(160), a comparator (170), a pulse generator (180) which controls a motor speed, and a magnetic resistor (40) which detects a output pulse width of pulse generator (180).

Description

Capstan motor driving circuit

1 is a schematic side cross-sectional structural view of a capstan motor.

2 is a conventional capstan motor driving circuit diagram.

3 is a circuit diagram of the present invention.

* Explanation of symbols for main parts of the drawings

10: rotor 12,13: magnet magnet

40: magnetoresistive element 60: free drive unit

70: motor drive unit 80: three-phase motor unit

90: microcomputer unit 100: current sensing unit

140: counter electromotive voltage sensing unit 150: zero sensing unit

160: latch portion 180: pulse generator

The present invention relates to a drive control circuit of a capstan motor for a VCR, and more particularly, to a capstan motor driving circuit capable of precisely controlling the motor speed and minimizing an output noise component without a phase detection sensor by a hall element or the like.

The capstan motor for driving the head drum in the VCR has a structure as schematically shown in FIG.

As described herein, a low-height cylindrical magnet 13 magnetized to 24 poles is formed on the inner wall surface of the rotor 10 in which the shaft 11 is inserted into the boss 21 on the substrate 20 so as to be rotatable. A cylindrical magnet 12 magnetized to a 360 pole is attached to an outer wall of the rotor 10. The number of magnetizing poles of the magnetizing magnets 12 and 13 may be changed according to design needs.

On the other hand, a plurality of coils 81 are arranged in a circular shape on the substrate 20 to face the 24 pole magnet magnet 13 to the mutual repulsion force and suction force of the plurality of coils 81 and the 24 pole magnet magnet 13. As a result, the rotor 10 is rotated, and the substrate 20 is provided with a plurality of Hall elements 30 for phase detection. In general, three Hall elements are installed in a three-phase motor-driven capstan motor.

A magnetoresistive element 40 is disposed near the 360-pole magnetized magnet 12 installed on the outer wall of the rotor 10 to adjust the motor speed.

The existing circuit for controlling the capstan motor of such a structure is shown in FIG.

As referred to herein, the phase detection signals of the Hall elements 30, 30 ', 30 " for detecting the position of each phase are passed to the predrive section 60 via the amplifiers 50, 50', 50 ", respectively. When input, the pre-drive unit 60 sequentially turns on / off each transistor 71-76 of the motor driver 70 to drive a driving current to each coil 81-83 of the three-phase motor unit 80. For example, when the transistors 71 and 76 are first turned on by the predrive unit 60, the motor driving current through the transistor 71 is passed through the transistor 76 through the coil 83 and the coil 82. Next, the pre-drive unit 60 turns on the transistors 73 and 75 so that the motor driving current through the transistor 73 exits through the transistor 75 through the coil 82 and the coil 81. Then, the transistors 72 and 74 are turned on so that the motor driving current through the transistor 72 passes through the coil 81 and the coil 83 through the transistor. It will exit through the stud 74.

Therefore, the driving current flows sequentially through each of the coils 81-83 of the three-phase motor unit 80 so that the rotor 10 of the motor rotates.

At this time, the magnetoresistive element 40 generates a pulse proportional to the rotational speed of the rotor 60 from the 360-pole magnetized magnet 12 and provides it to the microcomputer 90, thus pre-drive the microcomputer 90. By providing a control signal to the unit 60 to maintain a constant rotation speed of the three-phase motor.

However, such a conventional capstan motor driving control circuit brings a rise in product cost according to the demand of a relatively expensive Hall element, which results in a limited accuracy of the phase pulse signal by the element, thereby limiting sophisticated motor control. In particular, since the installation of a plurality of hall elements brings about an increase in the wiring length, a phase control error is easily caused by noise introduced on the wiring.

The present invention proposes a new capstan motor drive control furnace which can solve the problems of the existing capstan motor control circuit as described above.

The present invention achieves the phase signal for motor drive control by detecting the counter electromotive voltage of the three-phase motor and processing the same.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

3 is a circuit diagram of the present invention, in which the output of the pulse generator 180 and the start-up oscillator 200 are provided to the predrive unit 60 and connected to the output of the predrive unit 60. Accordingly, each transistor of the three-phase motor driver 70 composed of six transistors 71-76 is sequentially driven to sequentially supply current to each of the coils 81-83 of the three-phase motor unit 80.

The magneto-resistive element 40 is placed close to the three-phase motor unit 80 so that the speed-proportional pulse waveform detected by the magnetoresistive element 40 is compared to the reference voltage VR in the comparator 190 so that the pulse generator At 180, a pulse output control signal is provided.

Meanwhile, the output terminals of the transistors 71-76 of the motor driver 70 are connected to the counter electromotive voltage sensing unit 140 so that the counter electromotive voltage of the three-phase motor is detected, and the counter electromotive voltage sensing unit 140 is detected. The output of is configured to be compared to the output of the pulse generator 180 to the comparator 170 via the zero sensing unit 150 and the latch unit 160 is provided to the predrive unit 170.

In addition, the motor driver 70 is provided with a current sensing unit 100 by the resistor 101, the voltage detected by the current sensing unit 100 is compared with the reference voltage (Vr ') in the comparator 110 After that, the speed control output of the microcomputer unit 90 is again compared with the comparator 120, and then again compared with the reference voltage VR in the comparator 130 and configured to be provided as a motor speed control signal to the predrive unit 60. do.

Here, the two reference voltages VR are the same voltage and the reference voltage VR 'is a voltage due to the current limit signal.

Referring to the operation and effects of the present invention configured as described above are as follows.

In FIG. 3, when a start signal is input from the outside to the startup oscillator 200, the startup oscillator 200 sequentially drives each transistor 71-76 of the motor driver 70 by the startup oscillator 200. Generates an output to turn on / off.

For example, when the transistors 71 and 76 are first turned on by the pre-drive unit 60, the motor driving current through the transistor 71 exits through the transistor 76 via the coil 83 and the mid coil 82. Predrive 60 then turns on transistors 73 and 75 so that motor drive current through transistor 73 exits through transistor 75 via coil 82 and coil 81 and then The transistors 72 and 74 are turned on so that the motor driving current through the transistors 72 passes through the transistors 74 through the coils 81 and 83.

Therefore, the driving current flows sequentially through the respective coils 81-83 of the three-phase motor unit 80 to rotate the rotor 10 of the motor.

At this time, the magnetoresistive element 40 generates a pulse proportional to the rotational speed of the rotor 10 from the 360-pole magnetized magnet 12 and is compared to the reference voltage VR in the comparator 190 and then the pulse generator 180. To provide. Accordingly, the pulse generator 180 may provide the pulses adjusted to maintain the rotational speed of the three-phase motor to the microcomputer 90 and the predrive 60 directly and through the comparator 170, respectively. do.

On the other hand, the counter electromotive voltage signal drawn from each coil 81-83 of the three-phase motor unit 80 is detected by the counter electromotive voltage sensing unit 140 and compared through the phase zero sensing unit 150 and the latch unit 160. The unit 170 is compared with the output of the pulse generator 180 and then provided to the predrive unit 60.

That is, the phase zero error of the motor driver 70 of the pre-drive unit 60 is obtained by finding the phase zero point at the zero sensing unit 150 from the output of the counter voltage sensing unit 140 and latching the phase value to the latch unit 160. Will be corrected.

On the other hand, when a large current is supplied to the three-phase motor unit 80, the current sensing unit 100 detects this. That is, a current change flowing between both ends of the emitter resistor 10l of the motor driver 70 is drawn as a voltage component, and the external reference current limit signal VR 'voltage is compared with the comparator 110, and this is again referred to as the microcomputer 90. After comparing the current control signal with the comparator 120, the current limiting signal is provided to the predriver 60 through a comparison in the comparator 130 with the reference voltage VR. Therefore, by controlling the output of the motor driving unit 70 flowing the driving current under the control of the pre-drive unit 60 to the three-phase motor unit 80, the current provided to the three-phase motor unit 80 according to the load fluctuations. Stabilize it.

Therefore, the present invention accurately compensates the motor control phase error by detecting the phase by detecting the phase voltage of the three-phase motor instead of the phase detection hall element, thereby reducing the cost of eliminating expensive Hall elements and designing the wire noise countermeasures. It is possible to alleviate the overcurrent caused by the abnormal state of the three-phase motor and to ensure the stable operation of the capster motor by optimizing the supply of the motor coil current.

Claims (2)

In the capstan motor driving control circuit including the predrive unit 60, the motor driving unit 70, the three-phase motor unit 80, and the magnetoresistive element 40, each coil 81- of the three-phase motor unit 80 is provided. The counter voltage generated at 83 is configured to be sensed by the counter voltage sensing unit 140, and the phase is detected by the zero sensing unit 150 using the sensing counter voltage of the counter voltage sensing unit 140. After the phase detection signal of the sensing unit 150 is compared with the output of the pulse generator 180 by the comparator 170 via the latch unit 160, and provides a phase control signal to the predrive 60, Capstan motor drive circuit, characterized in that the output pulse width of the pulse generator (180) provided to the pre-drive unit 60 to limit the motor speed is controlled by the detection waveform of the magnetoresistive element (40). According to claim 1, wherein the motor driving unit 70 is provided with a current sensing unit 100 made of a current detection resistor 101, the detection signal voltage and the reference current signal voltage (VR ') of the current sensing unit (100). And a current control signal of the microcomputer (90) and a reference voltage (VR) to be connected to the pre-drive unit 60 to be provided as an output current control signal.