JPS6250907B2 - - Google Patents

Description

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

As a device for recording and reproducing video signals, there is a so-called VTR, which is becoming widely used for consumer use.

Due to the characteristics of its recording medium, magnetic tape, this VTR can easily provide both video signal recording and playback functions, allowing it to record television broadcast programs and easily operate using a television camera. It has the advantage of being able to record and enjoy certain images, but on the other hand, the device is complicated and therefore tends to be large, and in addition, the recording medium on which the program is recorded, so-called software, is relatively expensive. The drawback is that it becomes quite uneconomical as a video player that only performs playback.

However, in recent years, the demand for video software has increased in the same way as for audio disc records or music tapes, and the development of playback-only video players has become desirable. Replayers have appeared on the market.

This video disc player (hereinafter referred to as
As the name suggests, VDP uses a video disk in which signals are recorded along a spiral recording track from the outer periphery to the center (or in the opposite direction) on a disk-shaped recording medium. Therefore, as the disk rotates, the video signal must be reproduced while tracing this spiral recording track with an appropriate pickup for signal reading.

An example of such a VDP pick-up arm drive device is shown in FIG.

In the figure, 1 is an operation circuit for selecting and operating various operations required when using VDP, 2 is a pulse motor drive circuit, 3 is a pulse motor, 4 is a reduction mechanism, 5 is a DC motor drive circuit, 6 1 is a DC motor, 7 is a speed reduction mechanism, 8 is a drive switching mechanism, 9 is a pulley, 10 is a pick-up arm, 11 is a pick-up needle support lever, 12 is a pick-up needle, 13 is a video disk, and 14 is a belt.

In addition, video disk (hereinafter referred to as VD) 1
3 by appropriate means such as a turntable,
For example, the pick-up needle 12 is rotated at a constant speed of 900 rpm, and the pick-up needle 12 is rotated independently with respect to the arm 10 over a certain range, for example, a range of ±1 mm.
It is supported by a needle support lever 11 so as to be able to swing in a direction perpendicular to the tangential direction of the recording track of the VD 13, that is, parallel to the moving direction of the arm 10.
Although not shown, suitable tracking means, e.g.
Two types of tracking signals having different frequencies are recorded on the recording track of the VD 13 on both sides of the video signal at the center, and these are read out together with the video signal using the pick-up needle 12. By means such as swinging the pick-up needle support lever 11 left and right so that the levels of the two types of tracking signals are equal.
It is designed to accurately trace the recording track of VD13.

When the VDP is switched to video signal reproducing operation, a signal is given from the operation circuit 1 to the pulse motor drive circuit 2, which supplies drive power to the pulse motor 3 to rotate the motor 3. In parallel with this, a control signal is also applied from the operation circuit 1 to the switching mechanism 8, and the switching mechanism 8 is controlled so that the driving force is transmitted between the reduction gear mechanism 4 and the pulley 9.
Therefore, the drive of the pulse motor 3 is transmitted to the pulley 9 via the deceleration mechanism 4 and the switching mechanism 8, and from there the arm 10 is transferred to the VD 13 via the belt 14.
The pickup needle 12 is moved parallel to a line extending from the outer periphery toward the center, and the recording track is traced by the pick-up needle 12.

The moving speed of the arm 10 at this time is the so-called steady feed speed. For example, in a VD with a playback time of 60 minutes, the recording track width is 1.4 μm and the rotation speed is 900 rpm as described above. For example, the steady feed speed is 1.4 μm x 900 rpm
= 1.26mm/min. Therefore, the frequency of the drive power from the drive circuit 2 is determined so that the pulse motor 3 rotates at a rotational speed such that the arm 10 moves at a speed of 1.26 mm per minute.

In addition, in VDP, in order to give special effects such as slow-motion playback and high-speed playback to the reproduced image, it is necessary to make the movement speed of the arm 10 slower or faster than steady movement during playback.
For example, a feed speed such as 1/5 times faster than steady feed or 5 times faster is required. Therefore, in such a case, the frequency of the driving power supplied to the pulse motor 3 is increased to 1/5 times or 5 times that during steady feeding.

By the way, the operation of the VDP includes not only the video signal playback operation described above, but also the so-called movement of the arm 10 to a position off the surface of the VD 13 when the VD 13 is set on or removed from the turntable surface. Arm removal operation,
It is also necessary to carry out a so-called cueing operation in which the pick-up needle 12 is returned to the surface of the VD 13 from the position where it came off so that it is set near the recording track of the VD 13. Since it is desirable that the time required for such an operation be as short as possible,
It is desirable that the movement speed of the arm 10 be as fast as possible during the arm removal operation and the cueing operation. Therefore, for example, in these cases, the speed is about 2000 times the steady feed speed, that is, in the above example,
It is necessary to set a high moving speed of 1.26 mm/min x 2000 = 2520 mm/min, that is, about 2.5 m/min, a so-called rapid traverse speed. However, it is difficult to obtain a rapid feed speed of 2000 times the steady feed speed using the pulse motor 3, and it is difficult to obtain a rapid feed speed of 2000 times the steady feed speed from the pulse motor 3. In this case, it becomes necessary to use a pulse motor 3 having a large torque with a sufficient margin, resulting in a large cost burden. Therefore, during fast forwarding, a signal is applied from the operation circuit 1 to the DC motor drive circuit 5 to apply driving power to the DC motor 6. In parallel with this, a signal is also given to the switching mechanism 8, so that rotational power is transmitted between the speed reduction mechanism 7 and the pulley 9 at this time. In this way, during rapid feed, the arm 10 is fed by the DC motor 6, and is
This ensures smooth operation in response to speed changes of up to 10,000 times.

However, in the conventional example shown in FIG. 1, although the pulse motor 3 can be relatively small, two systems of power transmission mechanisms are required, and a switching system is required to switch between them. Since the mechanism 8 must be used, the overall configuration becomes quite complicated, which inevitably increases the weight and size of the device and the accompanying cost increase.In addition, it tends to lead to a decrease in reliability. There was a drawback.

SUMMARY OF THE INVENTION An object of the present invention is to provide a VDP pickup arm drive device that eliminates the drawbacks of the prior art described above and allows the arm to be driven by a single motor of relatively small capacity.

To achieve this object, the present invention is characterized in that the motor is switched between continuous and intermittent driving to accommodate the large speed ratio required for arm drive.

Hereinafter, an embodiment of a VDP pick-up arm drive device according to the present invention will be described with reference to FIGS. 2 and 3 of the drawings.

FIG. 2 shows an embodiment of the present invention, including an operating circuit 1, a DC motor drive circuit 5, a DC motor 6, a speed reduction mechanism 7, a pulley 9, a pick-up arm 10, a pick-up needle support lever 11, and a pick-up needle 1.
2. The VD 13 and belt 14 are the same as in the conventional example shown in FIG. 15 is a switch, arm 10
It has a function of detecting the amount of deviation of the needle support lever 11 of the pick-up relative to the amount of deviation and generating a control signal when the amount of deviation reaches a predetermined amount.A specific example thereof will be described in detail later.

Furthermore, when a signal is given from the operation circuit 1 to the DC motor drive circuit 5, the drive circuit 5 gives the drive power corresponding to the fast forwarding speed to the DC motor 6, and this motor 6 always operates at a speed corresponding to the fast forwarding. It is configured to rotate and move the arm 10 via the speed reduction mechanism 7, pulley 9, and belt 14.

Next, the operation will be explained.

When setting the VD13 on a turntable, replacing the VD13, or repeatedly playing the same program,
During the so-called arm removal operation and cueing operation, which are necessary before the start and end of the regeneration operation, a signal is sent from the operation circuit 1 to the DC motor drive circuit 5, and the drive power is continuously applied to the DC motor 6 for a predetermined period of time. is given, the DC motor 6 also rotates continuously for a predetermined period of time, and the arm 10 moves in a predetermined direction at a rapid traverse speed to perform an arm removal operation or a cueing operation. In addition, at this time, the pick-up needle 1
2, the tracking operation does not function at all, so the pick-up needle support lever 11 is at the neutral point position, and therefore the pick-up needle 12 is also located on the center line of the arm 10. It remains as it is.

During a playback operation for playing back a video signal from the VD 13, the arm 10 must be moved at a constant feed speed, which is accomplished as follows.

Now, arm 10 is moving to VD1 due to the cueing operation.
Suppose that it reaches a predetermined position on the surface of 3 and stops there. As a result, the pickup needle 12 rides on the recording track, the tracking signal and the video signal are read out as described above, the tracking operation is started, and the video signal is reproduced in a steady state. At this time, since the recording track of the VD 13 is in a spiral shape and the arm 10 is stopped, as the reproduction state continues, the pick-up needle support lever 11 moves as shown by the dotted line in Fig. 2 for tracking operation. It deviates like this. When this amount of deviation reaches a predetermined value, switch 15
is closed and a control signal is sent to the operating circuit 1.
The operating circuit 1 sends a pulse-like signal with a predetermined time width to the DC motor drive circuit 5 in response to the control signal from the switch 15, and rotates the DC motor 6 for a predetermined time. As a result, the arm 10 moves by a predetermined amount toward the right in the figure, so that the lever 11 returns to the position indicated by the solid line in the figure, and the switch 15 opens. Therefore, the arm 10 comes to a halt again. During this time, the pick-up needle 12 is being tracked by the support lever 11, so
Even if the arm 10 moves, it will not deviate from the recording track of the VD 13, and the video signal will be continuously and stably reproduced.

Then, while the VDP is in playback mode, the above operation is repeated, and each time the amount of deviation of the needle support lever 11 of the pick-up reaches a predetermined value, the DC motor 6 is rotated in a pulsed manner for a short time, and the arm 10 is moved by a predetermined amount. The arm 10 is made to follow the tracking operation of the pick-up needle 12 on the recording track of the VD 13, albeit intermittently, and from a microscopic point of view, it rotates in accordance with the fast-forwarding speed. With the DC motor 6,
This means that it is possible to obtain a steady feed speed that is only 1/2000 of that.

To give a concrete example of this speed and the driving state of the DC motor 6, when fast forwarding, the
Moves the entire recorded track part of the VD in about 1.8 seconds,
During steady feed, it moves in 60 minutes, so the ratio of those speeds is about 2000, as already explained. During rapid feed, driving power is continuously applied to the DC motor 6, whereas during steady feed, the same driving power is applied intermittently. Therefore, during steady feed, the DC motor 6
The ratio of the time when driving power is applied to the time when driving power is turned off should be 1:2000, for example, if driving power with a pulse width of 20 msec is applied at 40 second intervals. , the average moving speed of the arm 10 is 1/2000 of the rapid feed, and steady feed can be obtained.

Also, from the above, it is exactly the same when using 1/5x speed forwarding or 5x speed forwarding to give special effects to the reproduced image. For example, in the same case as above, when using 1/5x speed forwarding, respectively. Approximately 4msec
every 40 seconds with a pulse width of
It is also clear that the configuration may be such that driving power is applied every 40 seconds with a pulse width of 100 msec. Of course, it goes without saying that combinations of pulse widths and intervals other than these may be used, and it is also clear that the speed is not limited to 1/5 times or 5 times, but can be applied to any speed.

By the way, as mentioned above, when the driving power given to the DC motor 6 during steady feeding has a pulse width of 20 msec and an interval of 40 seconds, the deviation between the center line of the arm 10 and the pick-up needle 12 is The maximum width can reach several hundred micrometers, but as already explained, the width in which the needle support lever 11 can be tracked is 1 mm on the left and right, so there is sufficient tracking width, and the arm 10 is driven intermittently. Therefore, there is no possibility that the reproduction of the video signal will become unstable. According to the embodiment of the present invention shown in FIG. 2, rapid feed, steady feed, and various double speed feeds can be performed by using only one DC motor 6. The characteristics of torque characteristics and low cost are fully utilized, and all the drawbacks of the prior art can be eliminated.

FIG. 3 shows the switch 15 in the embodiment of FIG.
The needle support lever 11 was conceptually explained as
This is an embodiment showing a specific example of a means for detecting the amount of deviation between the needle support lever 1 and the center line of the arm 10.
1 is a needle control coil for swinging left and right with respect to the center line of the arm 10 to perform tracking; 17 is a transistor; 18 and 19 are + and -
20 is a tracking control circuit, 21 is a low-pass filter, 22 is a reference voltage source, 23 is a comparator, and 24 is a control signal output terminal.

The needle support lever 11 is configured to swing to the left or right depending on the polarity of the current flowing through the needle control coil 16, and the amount of swing is determined by the magnitude of the current flowing through the coil 16. A signal is sent from the control circuit 20 to the transistor 17 based on the level difference between the tracking signals read out by the needle 12, and the needle control coil 16
A current from the + power supply 18 or - power supply 19 is applied to the needle support lever 11 to deflect the needle support lever 11, thereby performing a tracking operation. Therefore, depending on the polarity and magnitude of the current flowing through the needle control coil 16, the needle support lever 1
A signal corresponding to the amount of deviation of one arm 10 from the center line is uniquely obtained.

Therefore, the polarity and magnitude of the current flowing through this needle control coil 16 are extracted as a voltage (the coil 16
(If the resistance of
3, and its output is extracted by comparing it with the voltage from the reference voltage line 22 that is applied to the other input. As a result, the output terminal 24 of the comparator 23 is connected to the needle support lever 1.
A signal is obtained only when the amount of deviation from the center line of arm 10 reaches a predetermined amount,
The signal from this terminal 24 is sent to the switch 15 in FIG.
The signal may be given to the operating circuit 1 in the same way as the signal from the .

The magnitude of the deviation amount at this time can be arbitrarily determined by the voltage of the voltage source 22, and thereby the state of steady feeding by the arm 10 can be adjusted. Further, at this time, if a hysteresis comparator is used as the comparator 23, intermittent feeding of the arm 10 can be specified more reliably. Of course, what is shown in FIG. 3 is only one embodiment of the deviation amount detection means, and any means that can detect the position without contact using photoelectric, electrostatic, or electromagnetic methods may be used. It goes without saying that any detection means may be used.

In addition, in the embodiment shown in FIG.
Although a DC motor 6 is used as the drive motor, it goes without saying that any motor can be applied to the present invention as long as it has the torque necessary for rapid traverse, and any motor such as an induction motor or a pulse motor can be used. It is possible to sufficiently achieve the object of the present invention even by applying a motor of the type shown in FIG.

As explained above, according to the present invention, VDP
All the feed operations necessary to drive the pick-up arm can be configured with a drive system consisting of a single motor, which eliminates all the drawbacks of conventional technology, resulting in a compact, lightweight, highly reliable product, and a significant cost reduction. It is possible to obtain a VDP pick-up arm drive device that can be expected to provide high performance.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional example of a pickup arm driving device for a video disc player, FIG. 2 is a block diagram showing an embodiment of a pickup arm driving device for a video disc player according to an embodiment of the present invention, and FIG. The figure is a circuit diagram showing one embodiment of the deviation amount detection means in the present invention. 1... Operation circuit, 5... DC motor drive circuit,
6... DC motor, 7... Reduction mechanism, 9... Pulley, 10... Pick up arm, 11... Needle support lever, 12... Pick up needle, 13...
video disk.

Claims (1)

[Claims] 1. Equipped with a pick-up arm drive motor that can constantly obtain the rotational speed necessary for rapid forward movement of the pick-up arm, and a tracking function that is independent of the movement of the pick-up arm. By driving the motor sequentially and intermittently in accordance with a tracking signal representing the amount of deviation of the motor, a steady feeding operation of the pick-up arm is obtained, and by continuously driving the motor, a rapid feeding movement of the pick-up arm is obtained. A pickup arm driving device for a video disc player according to the above method is provided with a detection means for detecting a DC component of the tracking signal, and the motor is intermittently driven each time the DC component reaches a predetermined value. A pick-up arm drive device for a video desk player, characterized in that the pick-up arm drive device is configured to obtain a steady feeding motion of the pick-up arm.