JPS6226848Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is equipped with two pickups that detect the signals recorded on both sides of the disc, and can be used without the need for reversing the disc.
The present invention relates to a disc playback device capable of detecting signals from both sides of a disc.

In recent years, many types of playback devices for disks on which audio or video information is recorded, such as video disk playback devices and PCM audio disk playback devices, have been developed. This type of disc playback device is provided with a pickup for detecting signals recorded on the disc, located only on one side of the rotated disc. Therefore, when playing back a disc with signals recorded on both sides using the above-mentioned device, once the playback of one side of the disc is completed, the user must remove the disc from the device, turn it over and insert it back into the device. This requires a complicated operation. Furthermore, when the information recorded on the other side of the disc continues from the information on the first side, there is a problem that blank time occurs when reproducing the series of information.

This invention takes into consideration the above-mentioned conventional problems, and by providing pick-ups on both sides of the disc, it is possible to play back both sides of the disc without reversing the disc. will be described in detail with reference to drawings showing one embodiment thereof.

In FIGS. 1 and 2, reference numeral 1 denotes a disk rotation motor, and a motor shaft 1' is positioned in the vertical direction. 2 is a turntable fixed to the edge of the motor shaft 1'; 3 is a PCM disk on which audio or video signals are recorded as PCM codes on both sides; 4 and 5 are opposed to the top and bottom surfaces of disk 3, respectively; two stylus-type first and second pick-ups for signal detection, 6 a pick-up drive motor; 7;
8 is a worm wheel that is meshed with the worm 7; 9 is a driving reel that is coaxially mounted with the worm wheel 8; 10a,
Reference numerals 10b, 10c, 10d, and 10e are reels for changing direction, and 11 is a wire that is secured to both pickups 4 and 5 and is wound and stretched around the drive reel 9 and each of the reels 10a to 10e for changing direction. When one of the pick-ups 4 or 5 is located opposite the outermost track 3a of the disk 3, the other pick-up 4 or 5 is engaged with the wire 11 in a position opposite to the innermost track 3b of the disk 3. At the same time, both pick-ups 4,
The wires 11 are redirected so that the wires 5 are moved in opposite directions.

Next, in Figure 3 showing the block diagram,
12 is a preamplifier that amplifies the output signals of both pickups 4 and 5; 13 is an end signal detector connected to the amplifier 12; Alternatively, when detected by the second pickup 4 or 5, the end signal is extracted from the output of the preamplifier 12 and output. 14 is a motor reversing circuit that reverses the rotational direction of the disk drive motor 1 based on the output of the end signal detector 13; 15 is a control flip-flop whose set terminal S is connected to the end signal detector 13; and 16 and 17 are respective circuits. The first and second pickups 4 and 5 control respective drive mechanisms including plungers and the like that move the pickups 4 and 5 up and down.
a control circuit, the first and second control circuits 16,
17 are connected to the non-inverting output terminal Q and the inverting output terminal of the flip-flop 15, respectively.

Next, the operation of the embodiment will be explained.

Now, as shown in FIG. 1, the playback needle of the first pick-up 4 is in contact with the outermost track 3a on the top surface of the disk 3, and the second pick-up 4 is detached downward from the disk 3, and the playback needle of the first pick-up 4 is in contact with the outermost track 3a on the top surface of the disk 3, and the second pick-up 4 is released downward from the disk 3 and Assume that it faces the innermost track 3b. When the pick-up drive motor 6 rotates in the forward direction in this state, the first pick-up 4 is moved toward the inner circumference of the disk 3 and the second pick-up 5 is moved toward the outer circumference of the disk 3 at a constant speed. The signals recorded on the upper surface of the disk 3 are sequentially detected by the reproduction needle 4, and the reproduction operation of the upper surface of the disk 3 is performed. At this time, since the playback needle of the second pickup 5 has come off the bottom surface of the disk 3, the playback operation on the bottom surface of the disk 3 is not performed.

Next, when the playback needle of the first pick-up 4 reaches the innermost track 3b on the top surface of the disk 3, the second pick-up 4 is located at the outermost track 3b on the bottom surface of the disk 3, and the first pick-up 4 picks up the disk 3. The end signal on the top surface is detected and amplified by the preamplifier 12. Furthermore, this end signal is extracted by the end signal detector 13, and the detection signal of the end signal detector 13 inverts the output of the flip-flop 15, making it non-inverting. The output signal of the output terminal Q becomes low level and the output signal of the inverted output terminal becomes high level, the first control circuit 16 removes the first pickup 4 from the disk 3, and the second control circuit 17 removes the second pickup 4 from the disk 3. 5 is moved upward and its regeneration needle comes into contact with the outermost track 3a on the lower surface of the disk 3. At the same time, the detection signal from the end signal detector 13 is input to the motor reversing circuit 14, and the pickup drive motor 6 is rotated in the opposite direction. Therefore, the second pickup 5 is moved toward the inner circumference while detecting the signal recorded on the lower surface of the disk 3, and the reproduction operation of the lower surface of the disk 3 is performed. and,
When the second pickup 5 reaches the innermost track 3b of the disk 3 and detects the end signal, the output signal of the flip-flop 15 is inverted, and the second pickup 5 is in a non-contact state with the disk 3 and the first pickup 4 is in a non-contact state. It comes into contact with the disk 3, and the same operation is repeated.

In the above embodiments, the stylus-type pick-ups 4 and 5 in which the reproducing needle contacts the disk 3 have been described, but the same applies to the stylus-type pick-up, for example, a capacitance detection-type pick-up or a laser beam-type pick-up. effect can be obtained. However, in the case of a laser beam type pick-up, since using two lasers would be too expensive, an optical fiber may be used to illuminate both sides of the disk.

As described above, according to the disc playback device of this invention, a pickup is provided on one side of the disc, which has signals recorded on both sides and is rotated by a motor, for detecting signals on that side. By providing a pick-up that detects the signal of the disc, it is possible to eliminate the complicated operation of taking out the disc, flipping it over, and setting it again when one side of the disc has finished playing. damage can be reduced.

Further, one pick-up is located on the outermost track on one side of the disk, and the other pick-up is located on the innermost track on the other side of the disk, and driving means moves both pick-ups in opposite directions and at the same speed. and a control means for detecting a signal from only one of the pick-ups, it is possible to continuously reproduce both sides of the disc with almost no blank time. Furthermore, by moving both pickups in opposite directions and at the same speed, only one driving means is required for both pickups, which simplifies the configuration.

[Brief explanation of the drawing]

The drawings show one embodiment of the disc playback device of this invention, with FIG. 1 being a simplified partially cutaway front view, FIG. 2 being a partial plan view, and FIG. 3 being a block diagram. 1...Motor, 3...Disk, 4, 5...Pickup.

Claims (1)

[Claims for Utility Model Registration] A disk on which signals are recorded in a clockwise spiral on both sides; a first pick-up facing the surface of the disk and located at the outermost periphery of the disk in an initial state; and the disk. a second pick-up that faces the back surface of the disc and is located at the innermost circumference of the disk in an initial state; and when the first pick-up moves radially on the disk, the second pick-up is different from the first pick-up. selecting a single drive means for connecting and moving the two pick-ups in order to move them in opposite directions at a constant speed; and selecting one of the two pick-ups;
a pick-up selection means for scanning the disk and detecting a signal; A disc playback device comprising rotation control means for switching the rotation direction.