JPS6141166Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a player such as a PCM disk or a video disk in which tracking of a recording track is performed by tracing a pick-up needle against a spiral guide groove.

Disc players that track using spiral guide grooves are used for audio disc records because they can perform reliable tracking even if the pick-up feed is quite rough or the disc rotation is slightly eccentric. It is also applied to PCM discs, video discs, etc., which have high-bandwidth, high-density recording methods, and is widely used, taking advantage of the fact that the purpose can be achieved with a relatively simple tracking machine groove. It is put into practical use.

By the way, in most of such PCM disks, video disks, etc., high-density recording is performed as mentioned above, and therefore the interval between guide grooves, that is, the track pitch is extremely narrow, for example, about 2 μm.

For this reason, it is generally impossible to manually set or remove a pickup disk, and most of the operations are fully automatic.

Therefore, in most cases, the so-called pause operation, which temporarily stops the playback operation, is performed automatically by operating a push button, etc., but with conventional disks. The player had a drawback in that part of the signal was lost when performing a pause operation.

This will be explained with reference to FIGS. 1 and 2.

In FIG. 1, 1 is the disk, 2 is the center of the disk, 3 is the center of rotation, 4 is the recording track,
5 is a pick-up arm, and 6 is a pick-up. Note that although the recording track 4 actually has a spiral shape, it is drawn as a circle for the sake of simplicity.

During the playback operation, drive disk 1 at a predetermined speed, e.g.
Rotating at 450 rpm, the arm 5 is moved parallel to a straight line from the outer periphery of the disk 1 toward the center 2, and the recording track 4 is traced with the pick-up needle provided on the pick-up 6 to reproduce the signal. As mentioned above, the advantage of a disk player using the tracking method using the guide groove is that even if there is some eccentricity in the rotation of the disk, it has almost no effect on the tracking of the pick-up needle itself; It is customary to reduce costs by maintaining the necessary degree of precision for the disk and its rotation mechanism in order to make the most of For example, a deviation of about 100 μm is allowed between the two.

Therefore, when the disc player is actually playing, track 4 of disc 1 does not have the maximum value.
As shown in FIG. 2, eccentricity of up to 200 μm (±100 μm) occurs each time the disk 1 rotates. Of course, as mentioned above, this does not cause any problem in normal playback operation.

However, suppose now that you perform a pause motion. Assume that the moment when the needle of the pick-up 6 leaves the track 4 of the disk 1 after entering the pause operation is point A in FIG. After that, when the pause operation is canceled and the pick-up 6 descends, and the pick-up needle reaches track 4 of disk 1 again, if it happens to be point C, the amount of eccentricity is almost the same, and therefore the pause There is no particular problem because the pick-up needle will enter track 4, which is almost the same as when the operation started, the playback signal will also enter the pause operation, and the signal will start playing again from the position where the playback operation was interrupted. The rotation phase of disk 1 when the pick-up needle leaves the surface of disk 1 after entering the pause operation, and the rotation phase of disk 1 when the pause operation is canceled and the pick-up needle descends onto the surface of disk 1 again. It is extremely rare that they match, and in most cases the rotational phases will be different.For example, it will naturally happen that you leave at point A in Figure 2 and then return to point B, and in this case the pose will be different. The track just before starting operation is 100μm (maximum is 200μm).
The pick-up needle ends up in a track that is far away (up to m), and the reproduced signal may not be continuous and may be missing. It should be noted that, of course, there may be cases where the reproduced signals overlap, but this does not pose much of a problem.

In the above example, the playback signal loss associated with this pause operation can reach up to 100 tracks and approximately 13 seconds of playback time, resulting in an extremely unpleasant playback condition, which is difficult for such disc players to perform. This has become a major drawback.

SUMMARY OF THE INVENTION An object of the present invention is to provide a guide groove tracking type disc player that eliminates the drawbacks of the prior art described above and prevents playback signals from being dropped even during pause operations.

In order to achieve this purpose, the present invention includes, while the pick-up hand is away from the surface of the disk at the beginning of the pause operation, the pick-up hand is returned by a predetermined amount in the direction opposite to the direction of movement of the pick-up arm during playback. The feature is that the pause operation can be canceled while remaining in that state.

Embodiments of the disc player according to the present invention will be described below with reference to FIGS. 3 to 7 of the drawings.

FIG. 3 shows an embodiment of the present invention, and FIG. 4 is a waveform diagram for explaining the operation of FIG.
is a recording track, 5 is a pick-up arm, 6 is a pick-up, 7 is a pulley, 8 is a belt, 9 is a motor, 10 is a motor drive circuit, 11 is a control circuit,
12 is an operation switch, and 13 is a pickup up/down coil.

Next, the operation will be explained.

The arm 5 is moved left and right by a motor 9 via a belt 8 that is stretched around a pulley 7, and during regeneration operation, it is moved by a forward rotation signal (FIG. 4C) from a control circuit 11. The disk 1 is moved by the disk 1, and moves in accordance with the movement of the spiral track 4 as the disk 1 rotates.

Now, at time t ₁ in FIG.
2 is operated and a pause signal b is given to the control circuit 11. As a result, the control circuit 11 stops supplying the normal rotation signal C to the motor 9, and
stop moving. At the same time, a pickup up/down signal e is supplied to the pickup up/down coil 13 to remove the pickup 6 from the surface of the disk 1 and stop the signal reproducing operation. The player will now enter a pause state.

Next, when the operation switch 12 is operated to cancel the pause operation at time _t2 , the supply of the pause signal b to the control circuit 11 is stopped. Therefore, the control circuit 11 supplies a reversal signal d to the motor 9, causing the motor 9 to rotate in the reverse direction, thereby returning the arm 5 in the opposite direction by a predetermined amount. The time during which the reversal signal d is supplied at this time is from time _t2 to time _t3 , and this time is set to a length necessary for the arm 5 to return approximately 200 μm. In other words, when the voltage of the reversal signal d supplied to the motor 9 is set to a constant value, the amount of movement of the arm 5 is determined by the time during which the reversal signal d is supplied, so the time t ₂ when the reversal signal d should be supplied. This means that the amount by which the arm 5 is returned can be set to a predetermined value, for example 200 μm, depending on the length from t ₃ to t 3 .

When the arm 5 is returned by a predetermined amount at time _t3 , the control circuit 11 switches the pick-up/up/down signal e supplied to the pick-up/up/down coil 13.
Lower the pick-up 6 onto the surface of the disk 1,
Trace by the pick-up needle is started and the signal reproduction operation is resumed. Therefore, this ends the pause operation, but at this time, the arm 5 always returns to its original direction by a predetermined amount, that is, 200 μm, from the position immediately before entering the pause operation. on the other hand,
The signal loss that occurs when entering the pause operation due to the eccentricity of disk 1 is at most the amount of eccentricity of disk 1, that is, 200 μm, so as shown in a in Figure 4, the signal is , B...G, and when a pause operation is started with signal G, the next time the pause is released, the signal that is played back will always start from the part before signal G (in the case of Fig. 4, F ), and it is possible to completely prevent signal loss and discontinuity.

5 and 6 show other embodiments of the present invention, in which a displacement coil 1 is connected to the pick-up 6 as shown in FIG.
4, and when entering the pause operation, the position of the pick-up needle of the pick-up 6 is displaced by a predetermined amount, that is, 200 μm, in a direction opposite to the moving direction of the arm during the playback operation by the displacement coil 14. It is. Note that the other configurations are the same as in the case of FIG. 3. FIG. 6 shows a mechanism for displacing the pick-up needle by the displacement coil 14, where 15 is the pick-up needle, 16 is a cantilever, 17 is the fulcrum of the lever 16, and 18 is a small permanent magnet.

When a current is supplied to the displacement coil 14, a magnetic field is generated, the direction and strength of which are determined by the polarity and magnitude of the current flowing through the coil 14. and permanent magnet 18
rotates around the fulcrum 17 due to this magnetic field,
Since the cantilever 16 is moved left and right, by controlling the current flowing through the displacement coil 14 with the control circuit 11, the pick-up needle 15 can be returned by a predetermined amount when entering the pause operation, similar to the embodiment shown in FIG. It is possible to prevent the reproduction signal from being lost due to the pause operation, and to prevent the signal from becoming discontinuous.

In the embodiment shown in FIG. 3, for example, a circuit as shown in FIG. 7 may be used to rotate the motor 9 driving the arm 5 in the forward or reverse direction.

In the figure, 19, 20 are inverters, 22-
25 is a power transistor.

When the normal rotation signal C is supplied, the transistor 22,
25 becomes conductive, a current in the forward direction flows through the motor 9, and the motor 9 rotates in the forward direction.

Further, when the reverse rotation signal d is supplied, the transistors 23 and 24 become conductive, so that current flows in the opposite direction to the motor 9, causing the motor 9 to rotate in the opposite direction. Of course,
It goes without saying that the motor 9 must be a direct current motor whose rotational direction is opposite depending on the direction of current, for example a permanent magnet field type motor.

In the above embodiment, the operation of returning the pick-up needle by a predetermined amount in the direction opposite to the feeding direction during playback by the reverse rotation of the motor 9 or by the displacement coil 14 is performed when the pause operation is canceled and the pick-up needle moves to the disk. Although it is designed to be performed immediately before descending to the surface, this action may be performed at any time during the pose action, so it may be determined arbitrarily.

As explained above, according to the present invention, it is possible to completely prevent the loss of the reproduced signal due to the pause operation with a simple configuration, so that the invention fully utilizes the advantages of the guide groove tracking method while eliminating the drawbacks of the conventional technology. It is possible to provide a reliable and low-cost disk player.

[Brief explanation of the drawing]

FIGS. 1 and 2 are conceptual diagrams and waveform diagrams for explaining signal loss in the conventional example, and FIGS. 3 and 4 are schematic diagrams showing an embodiment of the disc player according to the present invention and its operation. Waveform diagram for explanation,
5 and 6 are schematic diagrams showing other embodiments of the present invention and a diagram of the displacement mechanism of the pick-up needle, and FIG. 7 is a circuit diagram showing an embodiment of the circuit for rotating the motor in the forward and reverse directions. be. 1: Disk, 5: Pick up arm, 6:
Pickup, 9: Motor, 10: Motor drive circuit, 11: Control circuit, 12: Operation switch, 1
3: Pickup up and down coil, 14: Displacement coil.

Claims (1)

[Scope of utility model registration request] In a disk player that uses a spiral guide groove to track a recording track, there is a means for moving the pick-up needle away from the disk surface in response to a pause operation signal, and a means for moving the pick-up needle away from the disk surface when in the pause state. and a means for returning the pick-up needle to the disk surface by a pause operation cancellation signal while the pick-up needle is returned by the predetermined amount by the means, and the reproduction signal is prevented from being lost due to the pause operation. A disk player characterized in that it is configured to prevent such occurrence.