JPH02128370A - Information signal recording and reproducing method - Google Patents

Abstract

PURPOSE:To record and reproduce an information signal in a wide band by recording and reproducing 1st and 2nd dividing signals respectively obtained at the fall and the rise of a PWM(pulse width modulation) signal and performing the exclusive OR operation of 1st and 2nd reproduced dividing signals which are reproduced so that a reproduced PWM signal may be obtained. CONSTITUTION:A 1/2 frequency divider 13 obtains the 1st dividing signal triggered at the fall of the PWM signal which is obtained by modulating the pulse width of the information signal so that the PWM signal is 1/2 divided and a 1/2 frequency divider 14 obtains the 2nd dividing signal triggered at the rise of the PWM signal so that the PWM signal is 1/2 divided. Both dividing signals are recorded in a recording medium 19 together. A synthesis circuit 22 performs the exclusive OR operation of the 1st and the 2nd reproduced dividing signals reproduced from the recording medium 19 to obtain the reproduced PWM signal and the information signal is obtained by demodulating the pulse width of the reproduced PWM signal. Thus, the pulse width of each pulse of the PWM signal is accurately restored even if the variation of a recording and reproducing state such as the variation of a beam spot, etc., occurs and recording and reproducing the information signal in the wide band is accomplished.

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 signal recording and reproducing method for recording and reproducing information signals on a recording medium.

[Conventional technology]

2. Description of the Related Art Conventionally, information signals such as video signals have been recorded on optical disks or magnetic tapes and then reproduced.

In the case of the above recording, the video signal shown by the solid line in FIG. 3(A) is compared with the sawtooth wave shown by the solid line
PWM) to obtain the PMW signal shown in the same figure (B),
Normally, recording is performed using this PWM signal.

Here, the rising edge of the rectangular wave coincides with the falling edge of the sawtooth wave, so the PWM signal is triggered at the falling edge and the frequency is divided by 2 to record using the divided signal shown in the same figure (C). Even if this is done, video signals can be recorded and reproduced.

In this case, the frequency of the sawtooth wave, which is limited by the frequency recordable on the recording medium, can be doubled, and the band of video signals that can be recorded and reproduced can be widened.

When the recording medium is an optical disk, the intensity of the laser beam is varied in accordance with the above-mentioned frequency division signal, and bits as shown in the figure (D>) are formed on the disk.

(Problem to be Solved by the Invention) However, during recording, the beam spot is uniformly narrowed due to the focus rotation of the laser beam, and the width of the bit formed on the CZ and disk is as shown in (E) in the same figure. It changes as shown in (F). The bit width in figure (D) is dl, which corresponds to the H level period of the frequency-divided signal, but in figure (E), (
F) bit width d2 (d2 < d+ ), d3 (
d+<63) does not correspond to the 1'' level period of the frequency divider:;).

Furthermore, during reproduction, if the beam spot is not uniformly narrowed, the reproduced signal will not correspond to pitch 1 to width.

For this reason, the pulse width of the PWM signal in Figure (B) is 10 to 1
There was a problem in that it was not possible to accurately restore each of the five video signals, and wideband recording and reproduction of video signals could not be realized.

Also, write the above frequency division im number on the magnetic j----B.'&A1r
Even when the value is +1, the same problem occurs due to fluctuations in the contact state of the magnetic head with respect to the magnetic tape.

The present invention has been made in view of the above points, and it is possible to accurately restore the pulse width of each pulse of the PWM signal even if there are fluctuations in the recording/reproduction state, and information (1:"+Kffυl wide?i!・
The purpose is to capture and provide 10,000 types of information signal recording 1r) that can realize recording and reproduction of the area.

[Cenari to solve problems]

In the information signal recording and reproducing method of Mizumoto 15, the first frequency divider is used to change the pulse width of the information signal J1 (,.../: PWM
The falling edge of the signal e is triggered and the first frequency divided signal is obtained by dividing the +'WM signal by 1/2.1, the second frequency divider is PW
When the M signal rises, it is triggered and the PWM signal is halved.
Obtain the 20th frequency divider number. No. 1 above. The second frequency division A3 (C1.) are both recorded on the W recording medium.

The synthesis circuit performs an exclusive OR operation on the first reproduced frequency-divided signal and the second reproduced frequency-divided signal reproduced from the recording medium to obtain a reproduced PWM signal, and pulse-width demodulates the reproduced PWM signal. Obtain information signals.

[Effect]

In the method of the present invention, the rise of the PWM signal.

L' from each rising point? No. 1. The second frequency-divided signal is recorded and reproduced, and the reproduced '1. In order to obtain the reproduced PWM signal by the exclusive OR operation of the second reproduced frequency-divided signal, the reproduced PWM signal is
The pulse width of each pulse of the WM signal is the same as the pulse width of each pulse of the PWM signal during recording, regardless of fluctuations in the recording/reproduction state.
Therefore, this PWM signal can be restored. This realizes broadband recording and reproduction of information signals.

〔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, a video signal is input to terminal 10, and PW
The signal is supplied to the M modulator 11, where it is compared with the sawtooth wave to obtain a WM signal as shown in FIG.

This PWM modulated signal j is divided by +/2 frequency divider 13, 1
4. The 1/2 frequency divider 3 is a T-type flip-flop with a rising edge and a rising edge.
A first frequency-divided signal is generated. The 1/'2 frequency divider 14 is a positive-triggered ■-type flip;
Shown in figure (C)? A second frequency-divided signal is generated.

No. 1 above. The second frequency division number is a laser diode driver (LDD) '16G in the optical base 15.

A laser diode (LD) 17 is supplied to the first laser diode (LD) 17 to drive the LDDI 6. The first . A second beam (f) is generated,
A disk 19 as a recording medium which is rotated at high speed by a rotating shaft 18 is irradiated with light. Redbeam is disk 19
radially adjacent positions are irradiated.

As a result, a rack is formed on the surface of the disk 19 corresponding to the H level of the first frequency-divided signal to the first 1 of the bits shown in FIG. The bits shown in FIG. 3E are formed corresponding to 1 level of the frequency-divided signal, forming a second track. Figure 2 (D), (
E) shows the bit shape formed in the standard state where the beam spot is -, but when the beam spot changes, the bit shape of each of the 1st and 2nd tracks changes as shown in Fig. 2 (F).
.

The bit width becomes smaller as shown in (G), and the bit width becomes smaller as shown in (G).
K>, the bit width increases as shown in (L). The starting points of the arrows in Figure 2 ([2], (G), (K), and (L)) correspond to the bit end position formed in the standard state, and the length of the arrow represents the displacement of the bit end. ing.

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 that reach the disk 19 are photoelectrically converted by a photodiode (PD) 20, and depending on the presence or absence of a bit, the first and second reflected beams are (+) or 1. as shown in FIGS. 2(M) and (N). Second reproduced frequency-divided signals are obtained, which are amplified by the head amplifier 21 and supplied to the synthesis circuit 22. Figure 2 (1-1>, (I)
is the same figure (G).

Figure 2 (M) is the reproduced frequency divided signal from the track in (G).
, (N) are reproduced frequency-divided signals from the tracks (K) and (L) in the figure.

The synthesis circuit 22 is an exclusive OR circuit, and the second
(H), (1) or as shown in FIG. 2 (L), (M). Exclusive OR operation is performed on the second reproduction frequency divided signal to obtain the reproduction PWM signal shown in FIG. 2(J) or FIG. 2(0). Figure 2 (J).

(0) The pulse width T o = T s of each pulse of the reproduced PWM signal shown in each case is the pulse width T of each pulse of P WM length divided by the width shown in FIG. - Matches T5. Second
Figures (D) and (E) show the pulse width of each pulse of the reproduction PWM signal obtained from the reproduction frequency division signal of the indicated track (A
It goes without saying that the pulse width of each pulse of the PWM signal of > matches the pulse width of each pulse of the PWM signal.

The PWM demodulator 23 includes, for example, a low-pass filter.

The reproduced PWM signal is demodulated into a video signal and output from the terminal 24. In PWM demodulation, if the pulse width of each pulse is the same as that during recording, demodulation is possible even if the phases are different, so the original video signal can be obtained from each of LJ) and (0) in FIG.

Also, the first . Since the second frequency-divided signal has half the frequency of the PWM signal, the carrier frequency can be raised to twice the upper limit frequency that was previously possible, thereby widening the video signal band. becomes possible.

Although the above embodiment has been explained using an optical disk recording/reproducing apparatus as an example, this may be applied to a rotary head type magnetic recording/reproducing apparatus. In this case, the first rotary drum is oriented approximately 180 degrees from the rotating drum. Attach the two heads to the second head mounting position by arranging them in the direction of the rotational axis and cutting them.
Four heads are required.

〔Effect of the invention〕

As described above, according to the information signal recording and reproducing method of the present invention,
The pulse width of each pulse of the PWM signal can be accurately restored even if there is a change in the recording/reproducing state such as a change in the beam spot.
It is possible to record and reproduce information signals over a wide TI range, which is extremely useful in practice.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of an optical disk recording and restoring device to which the method of the present invention is applied, Fig. 2 is a waveform diagram for explaining the operation of the method of the present invention, and Fig. 3 is a waveform diagram for explaining the conventional method. It is a diagram. 11... PWM modulator, 13.14... 1/2 frequency divider, 19... disk, 22... synthesis circuit, 23.
...l'WMm adjuster. Patent applicant TIATSUKU Co., Ltd. Kimidazu Rinzu Fl +Gl (==) l-CD-4 (==)

Claims (1)

[Claims] Video signal processing in which a PWM signal obtained by pulse width modulating an information signal is recorded on a recording medium, and the reproduced signal obtained by reproducing from the recording medium is pulse width demodulated to obtain an information signal. In the recording/reproducing method, the PWM signal is triggered by the falling edge of the PWM signal.
a first frequency divider that obtains a first frequency-divided signal divided by /2, and a first frequency divider that is triggered at the rising edge of the PWM signal and divides the PWM signal into
a second frequency divider that obtains a second frequency-divided signal divided by /2, and an exclusive OR operation of the first reproduced frequency-divided signal and the second reproduced frequency-divided signal reproduced from the recording medium. Perform regeneration PWM
and a synthesis circuit for obtaining a signal, records both the first and second reproduced frequency-divided signals on the recording medium, and demodulates the reproduced PWM signal in pulse width to obtain an information signal. Signal recording and playback method.