JPS592976B2 - Information recording medium and its reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an information recording medium and a reproducing apparatus thereof, which uses a plurality of signals of different frequencies between information signal recording tracks as reference signals for tracking control, and further uses the signals on a time axis. By using it as a signal for error detection, it can reduce interference such as bead interference to the main information signal when recording signals other than video signals, and it can also facilitate time axis error detection. It is an object of the present invention to provide an information recording medium and its reproducing apparatus that can obtain a time axis error detection signal with a good signal-to-noise ratio even when the signal to noise ratio is 30.

Conventionally, in order to correct time axis errors, there has been a method of controlling the speed of a turntable such as a video disc or driving an arm stretcher to move a signal conversion element such as a scanning needle in the track scanning direction. If the recorded information is a video signal, a color burst signal or a horizontal synchronization signal could be used to detect the time axis error signal.

However, when using a color burst signal, there is a problem that the color burst signal is interrupted during the vertical blanking period and the frequency is too high, and when using a horizontal synchronization signal, it is necessary to keep the S/N ratio sufficiently high at all times. There were many problems, such as the fact that it was difficult to do so, and if tracking was not performed, it was impossible to extract any of the signals mentioned above.

Furthermore, when the recorded information is an audio signal, since none of the above signals are present, another signal must be added. The present invention eliminates the above-mentioned drawbacks, and an embodiment thereof will be described below with reference to the drawings.

The present invention is designed to constantly obtain a time axis error detection signal with a good S/N ratio.
This invention is based on one of the two or more inventions proposed in No. 809 (Japanese Unexamined Patent Publication No. 52-123205), and uses the reference signal for tracking control for detecting a time axis error signal.

In other words, the above-mentioned invention proposed by the applicant is “
A plurality of reference signals having different frequencies are respectively inserted and recorded in at least adjacent first and second information signal non-recorded portions of a track formed by recording information signals on a recording medium, and the information two signals are recorded. , an information signal recording system characterized in that a reference signal is recorded so as to be reproduced by a signal conversion means that scans and reproduces the recording medium during reproduction. FIG. 1 shows a block system diagram of three recording systems of an embodiment of the information recording medium according to the present invention.

As an example, a video disk in which the information signal is a video signal and the recording medium is a rotating recording disk (hereinafter referred to as disk) will be explained. In the figure, 1 is an oscillator, which oscillates the color subcarrier frequency of the video signal to be recorded, for example, 3.58 MHz. The signals are output to the circuit 7 respectively. The circuit 2 counts down the input frequency to n1/m1 (m1 and n1 are positive integers), and the circuit 3 counts down the input frequency to N2/M2 (M2 and N2 are positive integers).

Here, as an example, n1=N2-1, m1=4, M2=
6, the respective outputs of the circuits 2 and 3 have 894.
9kHz and 596.6kHz are obtained. These respective output signals (shown in FIG. 3B and C) are sent to the switching circuit 4.
Here, the signal is alternately switched and outputted every rotation of the disk to be recorded by the output of the synchronizing signal generator 5, and is modulated by the modulator 6. On the other hand, in the video signal processing circuit 7, the video signal to be recorded is subjected to signal processing together with the synchronization signal from the synchronization signal generator 5 and the oscillation output signal of the oscillator 1 to produce the signal shown in FIG. Modulator 8
, where it is frequency modulated.

As a result, the video signal frequency-modulated by the frequency modulator 8 is written on the spiral or concentric track shown by I in FIG. A single frequency signal from the modulator 6 is recorded as a reference signal for tracking control in a part of the track I, for example, with a period of one horizontal scanning period (1H) and alternately for one rotation of the disk, as shown in FIG. 3D. be done.

Since a reference signal for tracking control is recorded on a disc recorded in this way, there is no need to specifically form a guide groove for a scanning needle for reproduction, and countless pits are formed on a disc with a flat surface. Ru.

Therefore, this makes it possible to increase the contact area between the scanning needle and the disk, thereby making it possible to extremely extend the life of the scanning needle and the disk. However, a needle guide groove may be provided as in the conventional case. Therefore, the information recording medium according to the present invention changes the frequency of a plurality of (one) signals recorded as tracking control reference signals to a certain constant frequency n1.
/m1・N2/M2, ・・・・・・・・・ Ni/Mi
(m1, M2, ......, Mi, and n1,
N2, ......, Ni is any positive integer)
This was selected because of the double relationship.

FIG. 2 shows a block diagram of an embodiment of the information recording medium reproducing method according to the present invention.

The three types of signals, the video signal and two single frequency signals picked up by the head 9, are supplied to a demodulator 10 and band filters 11 and 12, respectively, and the video signal demodulated by the demodulator 10 is sent to a sync separation circuit. The signal is supplied to a signal processing circuit 14 together with the synchronization signal separated by 13, where the signal is processed and converted into a video signal in the original signal form. On the other hand, since the center frequencies of the pass frequency bands of the band filters 11 and 12 are selected to be 894.9 kHz and 596.6 kHz, the 894.9 kHz and 596.6 kHz
The Hz signal is separated and supplied to one of the detection circuits 16 and 17 via the switching circuit 15, respectively.

Here, the polarity of the signal obtained as the tracking control reference signal differs every time the disk rotates, and the driving direction to the tracking control element is reversed every time the disk rotates.
The switching circuit 15 switches the input to the detection circuits 16 and 17 every rotation of the disk in response to a synchronization signal from the synchronization separation circuit 13. The two tracking control reference signals are envelope-detected by detection circuits 16 and 17 and converted into DC voltages, and then supplied to a differential amplifier 18 .

The tracking control signal of polarity and level obtained from the differential amplifier 18 according to the track deviation direction and deviation amount causes the servo mechanism (not shown) to constantly track and scan the track I. make it work as it should. By the way, in this embodiment, the output tracking reference signals of the band filters 11 and 12 are k1/11
, K2/12 (11, 12, k1, K2 are positive integers) are applied to down-down and multiplier circuits 19 and 20, respectively.

Now, as an example, k1-K2-1, 11=3, 12=2
Then, 298.
A signal of the same frequency of 3 kHz is obtained. Since these signals are frequency modulated by the time axis error component,
The error signal is supplied to a detection circuit 21 to be detected, and further passes through a driver 22 to drive the rotation speed of the turntable or the arm stretcher. In this way, since the output frequencies of the down-converter and multiplier circuits 19 and 20 are made the same and both frequencies are used, there may be cases where tracking is lost for some reason and only one of the tracking control reference signals is reproduced. The time axis error signal can be detected without any problem. Note that the present invention is not limited to the above embodiments; for example, n1=3, N2=2, m
1=M2l3, k1-K2=1, 11-3, 12=2, and in this case, the tracking control error signal becomes 826.0kHz and 1550.7kHz, respectively.
The frequencies are respectively three times and twice 35/2 of the horizontal scanning frequency.

It is possible to take other integers other than these, in short, n
The relationship 1/M, x k1/11, N2/M2 x K2/12 may be satisfied. According to this method, even on a disc on which audio signals are recorded, time axis errors can be detected using the same signal. Furthermore, the invention is not limited to disks, and can also be applied to cylindrical recording media. Further, the tracking control reference signal may be a signal having a certain band instead of a single frequency. Furthermore, in the above embodiment, it has been explained that the reference signal is recorded cyclically between the tracks provided with the guard band, but in a recording body with a track pattern without a guard band, the reference signal is recorded at a position different from the scanning center position of the information recording track. The desired purpose can be achieved by cyclically recording reference signals on a reference signal track formed with the center at .

As described above, the information recording medium and the reproducing apparatus thereof according to the present invention are characterized in that the information signal recording tracks are formed with their centers at positions different from the track scanning center position on the recording medium in which they are arranged next to each other. , n at a certain frequency
1/m1, N2/M2, Ni/M
i(n1, N2, ......, Ni,.ml,
A plurality of reference signals selected by M2, . In addition to differentially reproducing the tracking control signals, these reference signals are respectively k1/11, K2/12,...K
j/1j(k1, K2,...Kj.ll
, 12, ......, 1j is a positive integer) times, and multiplication is performed to obtain Nk/ml (N
．． k. m, 1 is any positive integer) times the frequency, then
By using the information signal as a signal for time axis error detection, the information signal is reproduced by a signal conversion means that can correct the time axis error, so it is possible to detect the time axis error regardless of the recorded signal. When recording signals other than signals, interference such as bead interference to the main information signal can be suppressed to a minimum, and even if a tracking error occurs, the Nlc/ml of the above-mentioned multiple constant frequencies can be suppressed.
One of the double frequency signals is always output, so
The time axis error signal can be detected even when tracking is not achieved, and compared to the conventional method of detecting the time axis error signal using a color burst signal, the signal is not affected by interruptions during the vertical blanking period. Without,
It has many advantages, such as being able to obtain a time axis error detection signal with a good S/N ratio, and having little time delay and little distortion because it does not demodulate the reference signal.

[Brief explanation of the drawing]

FIG. 1 is a block system diagram of a recording system of an embodiment of an information recording medium according to the present invention, FIG. 2 is a block system diagram of an embodiment of an information recording medium reproducing apparatus according to the present invention, and FIG. 3A -C and D are partially enlarged plan views of signal waveforms and track patterns at various parts in FIG. 1, respectively. 1... Oscillator, 2, 3, 19, 20...
・Down-down, multiplier circuit, 4, 15... switching circuit, 6, 8... modulator, 9... head, 10... demodulator, 11, 12...
band filter, 14...signal processing circuit, 16,
17, 21...Detection circuit, 18...Differential amplifier.

Claims (1)

[Scope of Claims] 1. A reference signal track formed with its center at a position different from the scanning center position of the track on a recording medium in which information signal recording tracks are arranged next to each other is provided with a certain frequency. n_1/m_1, n_2/m_2,...
..., ni/mi(n_1, n_2, ...
..., n_1, m_1, m_2, ......
・A signal conversion method in which a plurality of reference signals, each of which is selected by a number of times (mi is an arbitrary positive integer), is recorded cyclically at a predetermined period, and the plurality of reference signals scan the recording medium during reproduction. From the reproduction signal picked up by the means, the plurality of reference signals are differentially reproduced to produce a tracking control signal, and the plurality of reference signals are k_1/l_1 and k_1, respectively.
2/l_2, ......, kj/lj(k_1
, k_2, ......, kj, l_1, l_2
, . . . , lj is a positive integer) times, and multiplication is performed to obtain nk/ml (n, k
, l, m are arbitrary positive integers) times the frequency, and then
An information recording medium characterized in that the information is recorded so as to be used as a signal for time axis error detection. 2. On a recording medium in which information signal recording tracks are arranged next to each other, a reference signal track formed with its center at a position different from the scanning center position of the above track has a certain frequency of n_1/m_1, n_2/ m_2,...
..., ni/mi(n_1, n_2, ...
・, ni, m_1, m_2, ......, mi
is an arbitrary positive integer) from the reproduced signal picked up by the signal converting means that scans the information recording medium on which a plurality of reference signals are cyclically recorded at predetermined intervals. The reference signals are differentially reproduced to produce tracking control signals, and the plurality of reference signals are each k_1
/l_1, k_2/l_2, ......, kj
/lj(k_1, k_2, ......, kj,
l_1, l_2, .
/ml (n, k, l, m are arbitrary positive integers) times the frequency, and then used as a signal for time axis error detection, thereby correcting the time axis error. 1. A reproducing apparatus for an information recording medium, characterized in that the information signal is reproduced by: