JPH02128369A - Information signal recording and reproducing method - Google Patents

Abstract

PURPOSE:To prevent the distortion of the waveform of a reproduced information signal from occurring and to obtain interchangeability between recording and reproducing devices by varying the delay amount of either of 1st and 2nd reproduced dividing signals when a synthetic rectangular wave is deviated from 50% duty. CONSTITUTION:1st and 2nd dividing signals which are triggered at the rise and the fall of a rectangular wave obtained by shaping an FM modulation signal being an information signal so that the rectangular wave is 1/2 divided are recorded in a recording medium 19. Variable delay circuits 22 and 23 vary the delay amount of either of the 1st and the 2nd reproduced dividing signals reproduced from the recording medium 19 and delay them. A synthesis circuit 26 obtains the synthetic rectangular wave by performing the exclusive OR operation of both reproduced dividing signals and obtains the information signal after FM-modulating the synthetic rectangular wave. A control signal generation circuit 31 obtains a control signal for varying the delay amount of the variable delay circuits 22 and 23 according to the changing quantity of the synthetic rectangular wave when it is changed from 50% duty. Thus, the distortion of the waveform of the reproduced information signal is prevented from occurring and the interchangeability between the recording and reproducing devices is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an information signal recording and reproducing method, and more particularly to an information fC1 recording and reproducing method for recording and reproducing information signals on a recording medium.

[Conventional technology]

The present applicant previously filed a patent application dated November 7, 1988, entitled "Information Signal Recording and Reproducing System," to transmit information signals to FM.
It is modulated and shaped into a rectangular wave, and the frequency is divided into 1/2 by triggers at the rise and fall of this rectangular wave. A second frequency-divided signal is obtained, these are recorded together on a recording medium, and the first frequency-divided signal is reproduced from the recording medium. Information signal recording that can widen the band of information signals to be recorded and reproduced by reproducing the second frequency-divided signal to obtain a reproduced rectangular wave by exclusive decoding, and FM demodulating this reproduced rectangular wave. A rebirth ceremony was proposed.

[Problem to be solved by the invention]

If the recording medium is an optical disc, 1. The two laser diodes are driven by the second frequency-divided signals, respectively, and the first and second frequency-divided signals are used to drive two laser diodes. Bits are formed on the disk F by each of the second laser beams and recorded as two tracks.

Also, 1st. Irradiating the disk with a second laser beam,
Each beam is photoelectrically converted by two photodiodes and reproduced.

Here, if the optical disk device that performs recording and the optical disk device that performs reproduction are the same, the first reproduction frequency division signal and the second reproduction frequency division signal to be reproduced are as shown in FIG. 4(A). ,
As shown in (B), the phases have a phase difference of 90 degrees, similar to when recording.

However, if the optical disk devices used for recording and reproduction are different, the second reproduction frequency division signal may differ from the first reproduction frequency division signal due to installation errors of the two laser diodes, etc. in Figures 4 (C) and (D).
) each produces a phase difference as expected. (C) of the same figure shows a case where the second reproduction frequency division signal lags behind the first reproduction frequency division signal, and (D) of the same figure shows a case where it advances.

If such a phase shift exists, there is a problem in that waveform distortion occurs in the reproduced information signal when a reproduced rectangular wave is obtained and FM demodulated.

The present invention has been made in view of the above points, and it is an object of the present invention to provide an information signal recording and reproducing method that prevents the occurrence of waveform distortion of reproduced information signals and obtains n-compatibility between recording and reproducing devices.

(Means for Solving the Problems) In the information signal recording and reproducing method of the present invention, the first frequency divider is triggered by the rising edge of a rectangular wave obtained by shaping the FM modulated signal obtained by FM modulating the information signal. A first frequency-divided signal is obtained by dividing the square wave by 1/2.

The second frequency divider is triggered by the falling edge of the rectangular wave, and obtains a second frequency-divided signal obtained by dividing the rectangular wave by 1/2.

The variable delay circuit delays at least one of the first reproduced frequency-divided signal and the second reproduced frequency-divided signal reproduced from the recording medium by varying the amount of delay.

The synthesis circuit performs an exclusive OR operation on the first reproduced frequency-divided signal and the second reproduced frequency-divided signal that have passed through the variable delay circuit to obtain a composite rectangular wave. This synthesized rectangular wave is FM demodulated to provide 4n information.
get a number.

Further, when the composite rectangular wave changes from 50% duty, the control signal generation circuit generates a control signal for varying the paper amount of the variable delay circuit according to the amount of change.

[Effect]

In the method of the present invention, when the synthesized rectangular wave deviates from the 50% duty, the first . By varying the delay amount of at least one of the second reproduced frequency divided signals, the first.
The phase difference of the second reproduced frequency-divided signal becomes a predetermined value, and there is no deviation. As a result, waveform distortion does not occur in the reproduced information signal even if the recording and reproduction apparatuses are different.

〔Example〕

FIG. 1 shows a block diagram of an embodiment of an optical disk recording/reproducing apparatus to which the method of the present invention is applied.

In the figure, during recording, the video signal input to terminal 10 is FM.
It is supplied to the transformer 11. The FM modulated signal obtained here is supplied to the limiter 12, where the upper and lower parts of the waveform are clipped to form a rectangular wave.

This rectangular wave FM modulated signal is passed through a 172 frequency divider 13.14
is supplied to The 1/2 frequency divider 13 has a rising trigger T.
is a type flip-flop and generates the first frequency-divided signal. The 1/2 frequency divider 14 is a T-type flip 7 with a falling trigger.
0, and generates the second frequency-divided signal.

No. 1 above. The second frequency-divided signal is supplied to a laser diode driver (LDD) 16 in the optical base 15, and the LD
The laser diode (LD) 17 is driven by the first laser diode (LD) 17 by driving the laser diode D16. The first frequency-divided signal has an intensity corresponding to each level of the second frequency-divided signal.
．． A second laser beam is generated and irradiated onto a disk 19 as a recording medium that is rotated at high speed by a rotating shaft 18 .

The laser beams are applied to adjacent positions on the disk 19 in the radial direction, and the first and second positions are irradiated with the laser beams. Bits are formed on the surface of the disk 19 in response to the H level of the second frequency-divided signal, and two tracks are formed.

During playback, the LDD 16 is the first. The intensity of the second laser beam is kept constant, and the first and second reflected beams from the disk 19 are photoelectrically converted by a photodiode (PD) 20.
Figure 2 (Δ), (B) or Figure 3 (Depending on the presence or absence of bits)
A>, the first as shown in (13). Second reproduced frequency-divided signals are obtained, which are amplified by the head amplifier 21 and supplied to variable delay circuits 22 and 23, respectively.

The variable delay circuits 22 and 23 each delay the first . The second reproduced frequency-divided signal is delayed and supplied to the synthesis circuit 26.

The synthesis circuit 26 is an exclusive OR circuit, and the first
．． Exclusive OR operation of the second reproduction frequency divided signal is performed to generate a reproduction wave FMvl as shown in FIG. 2(C) or FIG. 3(C).
Obtain the tonal signal. This reproduced FM modulated signal is supplied to a low-pass filter 27 and an FM demodulator 28.

The low-pass filter 27 integrates the reproduced FM modulated signal to obtain an average voltage. As shown in Fig. 2 (A) and (B), the first. When the second reproduction signals are shifted by 90 degrees from each other and the reproduction wave FM variable WJ signal has a duty of 50% as shown in the figure (C), the average voltage shown in the real image in the figure (D) is the reference voltage VREF. . Also, as shown in FIGS. 3(A) and (B), when the second reproduction frequency division signal leads the first reproduction frequency division signal by 8T, the third reproduction frequency division signal
The average voltage shown by the solid line in Figure (C) is lower than the reference voltage VREF by ΔV. The low-pass filter 27 outputs a phase error voltage obtained by subtracting the reference voltage vRE1: from the average voltage, and this phase error voltage is supplied to the adder circuit 24, has its polarity inverted by the inverter circuit 29, and is supplied to the adder circuit 25. .

The FM demodulator 28 demodulates a video signal from the reproduced FM modulated signal, and the video signal is output from a terminal 30 and supplied to a jitter detection circuit 31. The jitter detection circuit 31 generates a jitter correction voltage according to the jitter by comparing, for example, the horizontal synchronization signal of the video I& signal with a reference horizontal synchronization signal, and supplies this to each of the adder circuits 24 and 25.

The adder circuit 24 adds the phase shift error voltage to the jitter correction voltage to obtain a control m+ voltage and supplies it to the variable delay circuit 22.

The adder circuit 25 outputs the phase shift error voltage inverted to the jitter correction voltage and supplies it to the variable delay circuit 23 as a control voltage.

In the case of FIG. 2(D), since the phase shift error voltage is zero, the delay amount μ of each of the variable delay circuits 22 and 23 is the same, and only jitter correction is performed. In the case of FIG. 3(D), since the phase shift error voltage is -ΔV, the variable delay circuit 22 decreases the delay amount and the variable delay circuit 23 increases the delay amount accordingly. As a result, the first . The phase difference of the second reproduced frequency-divided signal is 90 degrees, and the reproduced FM modulated signal has a duty of 50%.

Therefore, no waveform distortion occurs in the video signal output from the terminal 30.

In addition, the first. The phase shift of the second reproduction frequency divided signal can be corrected, and the circuit structure is simple.

In addition, 1. The second reproduction frequency division (, the phase shift of H is the first
It is also possible to correct by varying the delay amount of either the reproduced frequency-divided signal or the second reproduced frequency-divided signal, and is not limited to the above example.

(Effects of the Invention) As described above, according to the information signal recording and reproducing method of the present invention,
It is possible to prevent waveform distortion of the reproduced information signal when the recording and reproducing apparatuses are different for recording and reproducing, and it is possible to obtain compatibility between the recording and reproducing apparatuses, which is extremely useful in practice.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of an optical disk recording/reproducing apparatus to which the method of the present invention is applied, and FIGS. 2, 3, and 4 are waveform diagrams for explaining the operation of the method of the present invention. 11...FM modulator, 12...Limiter, 13°1
4...1/2 frequency divider, 19...Disk, 22゜2
3... Variable delay circuit, 24.25... Kajun circuit, 2
6...Synthesizing circuit, 27...Low pass filter, 28...
- FM demodulator, 29...inverting circuit, 31... jitter detection circuit.

Claims (1)

[Claims] An FM modulated signal obtained by FM modulation of an information signal is recorded on a recording medium, and a reproduced signal obtained by reproducing from the recording medium is FM-modulated.
In an information signal recording and reproducing method that obtains an information signal by performing M demodulation, a first frequency-divided signal that is triggered by the rising edge of a rectangular wave obtained by shaping the FM modulated signal and divides the frequency of the rectangular wave by 1/2 is obtained. a second frequency divider that is triggered by the falling edge of the rectangular wave and obtains a second frequency-divided signal obtained by dividing the frequency of the rectangular wave by 1/2; a variable delay circuit that delays at least one of the reproduced frequency-divided signal and the second reproduced frequency-divided signal by varying the amount of delay; A synthesis circuit that performs an exclusive OR operation with a reproduced frequency divided signal to obtain a synthesized rectangular wave, and when the synthesized rectangular wave changes from 50% duty, the amount of delay of the variable delay circuit is varied according to the change. and a control signal generation circuit for obtaining a control signal for recording the first and second reproduction divided signals together on a recording medium,
An information signal recording and reproducing method characterized in that the synthesized rectangular wave is FM demodulated to obtain an information signal.