JPS6138540B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an arm feeding device for a video disc player.

FIG. 1 shows a conventional arm feeding device for a video disc player, and its operation will be explained. The recorded signal on the video disk 9 is read with the pick-up stylus tip 1. This read signal includes a video signal (including an audio signal) and a track signal. This signal is supplied to the signal processing circuit 2, and the two signals are separated using a bandpass filter or the like.
The video signal is transmitted to the video circuit 3, subjected to appropriate processing, and supplied to a cathode ray tube (not shown) to reproduce the image recorded on the video disk 9.

On the other hand, the track signal is transmitted to the coil drive circuit 5 via the needle control circuit 4 to drive the needle control coil 6. That is, the pick-up needle 8 is moved by using the magnetic field caused by the current of the coil 6 and the attraction and repulsion of the magnet 7.
is controlled so that the pick-up stylus tip 1 reproduces the signal recorded on the video disk 9 without track deviation.

Further, the displacement amount of the pick-up needle 8 is detected by the coil drive circuit 5, and the detection output that has passed through the low-pass filter 10 is supplied to the comparator 11 and compared with the reference voltage 12. When the value exceeds the value, a signal is output to the operation circuit 13 to drive the drive motor 15 of the arm 19 for a predetermined set time. Then, the motor 15 is driven for a scheduled time via the motor drive circuit 14, and the deceleration mechanism 16 and pulley 1 are driven.
7. Arm 19 moves a predetermined distance via belt 18.

FIG. 2 shows a detailed circuit configuration example of the coil drive circuit, low-pass filter, and motor drive circuit, and FIG. 3 shows a waveform diagram of the main parts. A needle control coil 6 is driven by a coil drive circuit 5 to control a pickup needle 8. Therefore, there is a proportional relationship between the current flowing through the needle control coil 6 and the amount of displacement of the pickup needle 8. The current flowing through the needle control coil 6 is extracted by changing the voltage with a resistor r. This is filtered by a low-pass filter 10 and its output is amplified by an amplifier 20.

The arm 19 is stationary and the pick-up needle 8
Since the control is performed such that no tracking deviation occurs, the amplifier 20 outputs a voltage that changes over time as shown in FIG. 11 is a comparator, and its 1 input has a reference voltage obtained by dividing the voltage of the power supply 21 by a resistor.
V ₁ is applied, and the output of the amplifier 20 is connected to the other input. Therefore, when the output of the amplifier 20 exceeds the reference voltage V ₁ , the comparator 11
The output of is inverted.

This inverted output is supplied to differentiating circuits C and R, and the monostable multivibrator 22 is triggered by the differentiating output. The waveform is shown in FIG. The output of the monostable multivibrator 22 drives the motor drive circuit 14 for a preset scheduled time _t1 , as shown in FIG. Therefore, the motor 15 is
The arm 19 is driven by a predetermined amount after being driven for ₁ hour. As a result, the pick-up needle control current flowing through the needle control coil 6 returns to its original state.

The arm 19 is controlled by the method described above, but in the conventional device, the arm drive motor 15 is suddenly driven, so the arm 19 moves rapidly, and the moment the motor 15 is driven, the pick-up needle 8 This has a major disadvantage in that the image may be misaligned from the playback track on the video disk 9, and the playback image may be disturbed.

SUMMARY OF THE INVENTION An object of the present invention is to provide an arm feeding device for a video disc player that eliminates the above-mentioned drawbacks of the prior art and solves the problems associated with pulse driving the arm drive motor.

The feature of the present invention is that the drive waveform of the arm feed motor is set to a waveform in which the voltage increases over time, such as a sine wave, a triangular wave, a staircase wave, etc., so that the motor is not driven suddenly. be.

An embodiment of the present invention is shown in FIG. 4, and a waveform diagram of its essential parts is shown in FIG. In these figures, the second,
The same symbols as in Figure 3 represent equivalent parts. As is clear from a comparison of FIG. 4 with FIG. 2, the present invention differs from the conventional example in that a triangular wave generator 23 and a drive circuit 24 are newly provided.

The needle control coil 6 is driven by the coil drive circuit 5,
The operation up to supplying a drive pulse to the motor drive circuit ₁₄ for the scheduled time t2 in response to the inversion of the output of the comparator 11 is the same as described above with reference to FIG.

The trigger pulse shown in FIG. 3 is supplied to the monostable multivibrator 22 and at the same time, it is also supplied to the triangular wave generation circuit 23. As a result, a triangular wave (FIG. 5a) whose voltage begins to rise in response to the application of the trigger pulse is supplied to the drive circuit 24. Therefore, the motor 15 is driven by a triangular wave, and its activation is performed gradually.

The triangular wave generating circuit described above may be of any known type, and very simply may be an integrating circuit using a resistor and a capacitor. Further, instead of the triangular wave, a sine wave or a staircase wave may be used, and examples of this are shown by waveforms b and c in FIG. in this case,
Since the motor 15 is started with voltages having waveforms indicated by b and c, respectively, the start-up is performed slowly as described above.

As described above, according to the present invention, since the arm drive motor is started with a voltage that gradually increases over time, the arm is not suddenly driven in a pulsed manner and does not move suddenly. Therefore, when the motor is driven and the arm moves, the pickup needle will not be displaced from the playback track on the video disk, and the playback image will not be disturbed.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional arm feeding device for a video disc player, Fig. 2 is a partial detailed block diagram of Fig. 1, Fig. 3 is a waveform diagram of its main parts, and Fig. 4 is a block diagram of an arm feeding device of a conventional video disc player.
The figure is a block diagram of one embodiment of the present invention, and FIG. 5 is a waveform diagram of its essential parts. 1... Pick-up needle tip, 2... Signal processing circuit, 4... Needle control circuit, 5... Coil drive circuit,
6... Needle control coil, 7... Magnet, 8... Pick-up needle, 9... Video disk, 11... Comparator, 13... Operating circuit, 14... Motor drive circuit, 15... Motor, 16... Reduction mechanism, 1
9... Arm, 22... Monostable multivibrator, 23... Triangular wave generation circuit, 24... Drive circuit.

Claims (1)

[Claims] 1 A pick-up needle drive circuit, a pick-up needle control coil, a circuit that detects the current flowing through the control coil and detects the amount of displacement of the pick-up needle, and when the amount of displacement of the pick-up needle reaches a predetermined value, In an arm feeding device for a video disc player, which is equipped with a circuit for driving an arm feeding motor for a predetermined time, the arm feeding motor is driven by:
An arm feeding device for a video disc player, characterized in that the arm feeding device for a video disc player is configured to operate using a voltage that gradually increases over time.