JPS6344382A - Reproducing device for information signal recording medium - Google Patents

Abstract

PURPOSE:To prevent a 3rd reference signal in a reproducing operation from interfering the beat of main information by switching a 1st and a 2nd reference signals based on the 3rd reference signal that a 2nd detection means detects. CONSTITUTION:A detection sensor 4 and a pickup 5 detect a main information signal and the 1st and the 2nd tracking control reference signals fP1 and fP2, all of which are recorded in the program section 24 of a video disk 21, and supply said signals to a switching circuit 14 through BPFs 9 and 10. A detection sensor 25 being the 2nd detection means, and a pickup 26 detect an index reference signal fP3 recorded in a read-in section 22, and supply said signal to a fP3 compensating circuit 16 through a preamplifier 27. The circuit 16 outputs a switching pulse to the circuit 14, which switches the polarities of the signals fP1 and fP2 outputted to a differential amplifier 17 with the aid of the switching pulse every time the video disk 21 makes one turn.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a reproducing apparatus for an information signal recording medium such as a disk.

<Summary of the Invention> The present invention is characterized in that main information signals such as video signals and audio signals are modulated to form a spiral main track as a change in geometrical shape and are recorded. First and second tracking control reference signals having different frequencies are alternately switched and recorded every one rotation period in a substantially intermediate portion, and an outer peripheral portion corresponding to this switching position.

In an apparatus for reproducing an information signal recording medium in which a third reference signal is recorded at one or both positions of the inner peripheral portion, the main information signal and the first reference signal are recorded. a first detection means for detecting a second reference signal; and a second detection means for detecting the third reference signal; Based on this, by performing a switching operation between the first and second reference signals, it is possible to prevent the third reference signal from overlapping the main information signal during playback.

<Prior art> Hereinafter, as a reproducing apparatus for this type of information signal recording medium, a VH
This will be explained using a D format video disc system as an example.

FIG. 3 is a plan view showing a signal recording pattern of a conventional video disc, and FIG. 4 is a block diagram of a tracking servo system circuit of a reproducing apparatus for reproducing the conventional video disc.

That is, in a conventional video disc, main information signals such as video signals, audio signals, or various data are modulated and continuously recorded on a spiral main track 1 as geometrical changes in a program section on the disc. At the same time, on the sub-truck 2 approximately in the middle between the trunks of the main truck 1,
First and second tracking control reference signals fPi fP2 having different frequencies are alternately switched and recorded every rotation period of the video disc, and the first and second reference signals fP1 . A third index reference signal f,3 having a different frequency from the above frequency is recorded at switching position A of fP2.

The video disk is rotated at a constant speed, and four fields of signals are recorded in one rotation. It is recorded superimposed on one of the signals V.

Next, a description will be given of a playback device that plays back a video disc on which each signal is recorded as described above.
Each signal recorded on the detection sensor 4. It is detected by the pickup 5, amplified by the preamplifier 6, and then divided into two parts.
One of them is supplied to a demodulator (not shown) to reproduce the main information signal. Moreover, the other side is a band pass filter 7
After the reference signal is separated into ν waves, it is supplied to the AGC amplifier 8. The reference signal supplied to the AGC amplifier 8 is controlled to a constant level, divided into parts, and supplied to band pass filters 9, 10, and 11, where they are discriminated and separated. The tracking control reference signals fPi'P2 outputted from the bandpass filters 9 and 10 are passed through the switching circuit 14 via the detectors 12 and 13, respectively.
supplied to On the other hand, the index reference signal fP3 outputted from the bandpass filter 11 is supplied to the compensation circuit 16 via the detector 15, and the compensation circuit 16 outputs a switching pulse to the switching circuit 13.

The switching circuit 13 switches the polarity of fPi and fP2 outputted to the differential amplifier 17 every rotation period of the video disc 3 using the switching pulse. The differential amplifier 17 outputs a signal according to the level difference between the supplied fPl and fP2, which passes through a phase compensation circuit 18 and a drive circuit 19, and then moves the detection sensor 4 appropriately in the radial direction of the video disc 3 by a tracking coil 20. let

<Problems to be solved by the invention> As mentioned above, the current VHD system is a CAV (Constant Angular HD system) in which a video disc rotates at a constant speed.
arMelocity) type,
In this method, since the vertical synchronization signal is recorded radially, the index reference signal is recorded over the vertical synchronization signal to prevent the index reference signal from interfering with the video signal. .

However, if we were to record information at a constant linear velocity in order to record it at a high density, we would have the following CL V (C
(instant Linear Velocity) type, the position at which the vertical synchronization signal is recorded is shifted between adjacent tracks, so the index reference signal cannot be recorded over the vertical synchronization signal, and repeat interference occurs between the reference signal and the video signal. happens. For this reason, conventional VHD video discs have CL, which allows high-density recording of information.
It was not possible to adopt V.

<Means for Solving the Problems> In order to solve the above problems, the present invention has the following features:
The outer periphery corresponds to the switching position of the reference signal.

The present invention provides a reproducing apparatus for reproducing an information signal recording medium in which a third reference signal is recorded at one or both positions of the inner circumference.

In other words, the main information signal and the above-mentioned 1. a first detecting means for detecting a second reference signal; and a second detecting means for detecting the third reference signal, the third reference signal being detected by the second detecting means; By performing a switching operation between the first and second reference signals, the third reference signal prevents the third reference signal from interfering with the main information signal during reproduction.

<Example> Embodiments of the present invention will be described below with reference to the drawings.

Incidentally, the same reference numerals are used for the same parts as in the conventional example, and the description thereof will be omitted.

FIG. 2 is a plan view showing a signal recording pattern of a video disc reproduced by the information signal recording medium reproducing apparatus of the present invention. Part lead-out section 2
3, and these lead-in section 22 lead-out section 23
The program is divided into three sections, with a wide program section 24 provided in between.

That is, the information signal recording medium targeted by the reproducing apparatus of the present invention contains the main information signal and the first . The second tracking control reference signal fil, fP2 is recorded in the program section 24 as in the past, and the third index reference signal fP3
Lead-in section 22. One side of lead-out section 23,
Alternatively, both the first and second reference signals fP1. It is recorded at a position corresponding to switching position A of f.

Next, a reproducing apparatus of the present invention for reproducing the video disc 21 will be explained. Here, it is assumed that the index reference signal f,3 is recorded only in the lead-in section 22.

The main information signal recorded in program section 24 and the first
．． The second tracking control reference signals fPI and fP2 are supplied to the detection sensor 4. The signal is detected by a pickup 5, amplified by a preamplifier 6, and then divided, and one of the signals is supplied to a demodulator (not shown) to reproduce the main information signal. The other signal is separated from the reference signal by a bandpass filter 7 and then supplied to an AGC amplifier 8. AGC amplifier 8 controls the supplied reference signal to a constant level,
Thereafter, this signal is divided into parts and supplied to band pass filters 9 and 10, respectively, where they are discriminated and separated. The tracking control reference signals fP1 and fP2 output from the bandpass filters 9 and 10 are sent to the detector 12, respectively.
．． 13 to a switching circuit 14.

On the other hand, the index reference signal f,3 recorded in the lead-in section 22 is detected by a detection sensor 25. It is detected by a pickup 26, a preamplifier 27, a bandpass filter 11. The signal is supplied to a compensation circuit 16 via a detector 15. The compensation circuit 16 outputs a switching pulse to the switching circuit 13, and the switching circuit 13 outputs the switching pulse to the differential amplifier 17.
, 1°f, and 2 are switched every rotation period of the video disc 21. The differential amplifier 17 receives the supplied f, 1 . f
, 2 outputs a signal according to the level difference between the phase compensation circuit 1
8. The detection sensor 4 is appropriately moved in the radial direction of the video disc 21 by the tracking coil 20 via the drive circuit 19.

The detection sensor 25 is fixedly provided at a position that does not interfere with the movement of the detection sensor 4. In this way, the index reference signal is recorded in the lead-in section 22 and detected by the dedicated detection sensor 25. For example, the index reference signal does not cause beat interference with the video signal, and high-quality video can be reproduced.

Although the above embodiment has been described using a CAV type video disc, the same applies to a CLv type video disc since an index reference signal is required for each revolution period. Further, the same effect can be obtained even if the index reference signal is recorded in the lead-out section 23.

When reproducing a recording medium in which index reference signals are recorded in both the lead-in section 22 and the lead-out section 23, the lead-in section 22. Dedicated detection sensors may be placed at locations corresponding to the lead-out section 23, and in this case, even if any index reference signal is missing due to scratches on the disc, dust, etc., tracking errors will occur. There is no risk of this happening.

<Effects of the Invention> As described above, the information signal recording medium reproducing apparatus of the present invention has the following effects:
Main information signal and 1st. The first detecting the second reference signal
and a second detection means for detecting a third reference signal, the first and second reference signals are detected based on the third reference signal detected by the second detection means. Since the signal switching operation is performed, it is possible to prevent the third reference signal from overlapping the main information signal, and to perform a reliable tracking operation.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a tracking servo system circuit of an information signal recording medium reproducing apparatus of the present invention, FIG. 2 is a plan view showing a signal recording pattern of a video disc reproduced by the apparatus, and FIG. 3 is a conventional FIG. 4 is a plan view showing a signal recording pattern of a video disc. FIG. 4 is a block diagram of a tracking servo system circuit of a conventional video disc playback device. 0 4.25...Detection sensor 5.26... Pickup, 6, 27...Preamplifier, 14...Switching circuit, 20...Tracking coil.

Claims (1)

[Claims] 1. Main information signals such as video signals and audio signals are modulated and recorded as a change in geometrical shape to form a spiral main track, and a frequency difference is recorded approximately in the middle between each track of the main track. Different first and second tracking control reference signals are alternately switched and recorded every rotation period, and a third reference signal is provided at one or both of the outer circumference, inner circumference, and the like, corresponding to this switching position. A device for reproducing an information signal recording medium on which a reference signal of
a first detection means for detecting the main information signal and the first and second reference signals; and a second detection means for detecting the third reference signal; A reproducing apparatus for an information signal recording medium, characterized in that a switching operation between the first and second reference signals is performed based on the detected third reference signal.