JP2804645B2 - Double-sided simultaneous playback disc record - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided simultaneous reproduction disc record in which reverse mounting can be easily identified.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 61-214244 (G1)
1B 7/24) discloses a disk record in which spiral recording tracks are formed in opposite directions, and information to be reproduced is recorded at substantially the same position on the front and back at the same timing.

If these disc records are reproduced and synthesized simultaneously, it is possible to reproduce wideband information. However, if the disc record is turned upside down when it is mounted, the disc will rotate in the reverse direction, and the recording track will scan backwards, making reproduction difficult. Therefore, it has been proposed to attach a label for identifying the front and back of the disk to the disk and warn the user not to mount the disk upside down.

[0004]

However, if the operator mistakenly mounts the camera upside down, reproduction becomes difficult. Therefore, it is necessary to detect reversal mounting even after mounting. However, providing a special detection means for the disk record increases the cost and is not easy to adopt. Therefore, there is a need for easy and quick discrimination between front and back without adding a special configuration to the disc.

[0005]

Therefore, the present invention is characterized in that the pitch of the lead-in track of the disk is set to be larger than the recording track pitch.

[0006]

According to the present invention, the absolute value level of the reverse polarity tracking error signal generated by the lead-in track scanning when the mounting is reversed is increased.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments.

First, according to the present invention, a wide-band high-definition video signal is distributed for each line to form narrow-band two-channel video information, and these video information are recorded on two disks whose rotation directions are reversed. The present invention is applied to a disc record for double-sided simultaneous reproduction which is bonded so that video information to be reproduced simultaneously is located at the same position on the front and back.

This embodiment is characterized in that, as shown in FIG. 1, an information recording track TI for recording the above-described two-channel video information and a lead formed on the inner peripheral side thereof for recording a lead-in signal. When forming the in-track TR, the pitch P0 of the lead-in track TR is formed to be larger than the pitch P1 of the information recording track TI.

When recording the disk record of this embodiment, it is only necessary to set the moving speed of the recording beam high during the recording period of the lead-in area, and no special change is required for the recording apparatus.

The main circuit blocks of a double-sided reproduction high-definition video disk player for reproducing the above-mentioned disk record are shown.

As is apparent from FIG. 1, in this embodiment,
A first pickup block 1 and a second pickup block 2 are opposed to each other with a disc interposed therebetween, and the reproduced signals are processed by first and second reproduced signal processing circuits 3 and 4, respectively, and then input to a reproduced signal synthesizing circuit 5. Then, it is converted into a high-quality reproduced video signal and derived. Each pickup block includes a pickup and a pickup motor, and inputs a reproduction signal reproduced by the pickup to first and second tracking control circuits 6 and 7 and first and second focus control circuits 8 and 9, respectively. A tracking control signal and a focus control signal are supplied to each pickup, and a DC component obtained by inputting each tracking control signal to the first and second DC separation circuits 10 and 11 is supplied to each pickup motor.

On the other hand, the disk motor 12 is driven by the output of a disk drive circuit 13. The disk drive circuit 13 inputs a servo signal to control the rotation of the disk motor 12 at a constant linear speed.

Hereinafter, the rising operation of this embodiment will be described. First, when a playback operation is performed with a disc record loaded, the first pickup 1A and the first focus control means 8 in the first pickup block 1 already arranged opposite to the lead-in area on the lower surface of the disc operate. To execute focus control. As a result, when the focus state is reached, the first focus control circuit 8 considers that a disk is mounted and
Activate 3 By this operation, the disk motor 12
Is activated and drives the disk record to rotate in one direction. During this activation period, the second pickup block 2
Moves from the retract position outside the disk to above the innermost lead-in area, and starts reproduction in the same manner as the first pickup 1A.

When the first pickup 1A reproduces and scans the lead-in area, the first tracking control circuit 6
Generates a tracking error signal, but when the disc is mounted in reverse, the tracking error signal is generated toward the negative side, that is, toward the inner peripheral side, and when the disc is mounted correctly, toward the positive side, that is, toward the outer peripheral side. Occur. Of course, the amplitude of the error signal increases faster than usual due to the large track pitch, and the inversion detection circuit 14 for identifying the polarity thereof.
Indicates that the disk drive circuit 1
3 to quickly and accurately supply the inversion command signal, and invert the disk motor 12 while the disk record is rotating at a low speed.

As a result, even in the case where the disk is mounted upside down, reproduction is possible in this embodiment.

[0017]

Thus, according to the present invention, the reversal mounting of a disc record can be detected quickly and reliably without adding any special detecting means, and the effect is great.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a disc record of the present invention.

FIG. 2 is a block diagram of a reproduction circuit of a disk player for reproducing a disk record according to the present invention.

[Explanation of symbols]

 TR Lead-in track TI information recording track

Claims (1)

(57) [Claims] 1. A disk record in which spiral recording tracks are formed in opposite directions and information to be reproduced is recorded at substantially the same place on the front and back at the same timing. A double-sided simultaneous reproduction disk record characterized in that an in-track pitch is formed larger than an information recording track pitch.