JPH02128368A - Information signal recording and reproducing system - Google Patents

Abstract

PURPOSE:To widen the band of an information signal such as a video signal, etc., which is recorded and reproduced by recording 1st and 2nd reproduced dividing signals in a recording medium together, FM-demodulating a synthetic rectangular wave and obtaining the information signal. CONSTITUTION:A 1/2 frequency divider 13 obtains a 1st dividing signal whose rectangular wave is 1/2 divided by being triggered at the rise of the rectangular wave obtained by shaping a signal to be FM-modulated which is FM- demodulated with a video signal and a 1/2 frequency divider 14 obtains the 2nd dividing signal whose rectangular wave is 1/2 divided by being triggered at the fall of the rectangular wave and both signals are recorded in the recording medium 19 together. A synthesis circuit 22 obtains the synthetic rectangular wave by performing the exclusive OR operation between the 1st reproduced dividing signal and the 2nd reproduced dividing signal reproduced from the recording medium 19 and the synthetic rectangular wave is FM-demodulated to obtain the video signal. Thus, the band of the information signal recorded and reproduced is widened.

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 are FM modulated, recorded on optical disks or magnetic tapes, and then reproduced.

In order to widen the band of the video signal in the above-mentioned FM modulation, it is necessary to set the carrier frequency to a high frequency. FIG. 3 shows the frequency spectrum of the FM modulated signal, in which the video signal band is expressed as fp.

(Problems to be Solved by the Invention) In order to record and reproduce the FM modulated signal, it is necessary to record and reproduce at least a carrier frequency corresponding to the white level.

However, there is an upper limit to the frequency that can be recorded on an optical disk or magnetic tape, and the above-mentioned carrier frequency is regulated by this upper limit frequency, resulting in a problem that a wide band of video signals that can be recorded and reproduced cannot be obtained.

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 allows a wide band of information signals to be recorded and reproduced.

[Means to solve the problem]

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 an FM modulated signal that has been FM demodulated using a video signal, and the first frequency divider divides the frequency of the rectangular wave into 1/2. Obtain the frequency-divided signal.

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

No. 1 above. The second frequency-divided signals are both recorded on the recording medium.

The synthesis circuit performs an IJF (l!!-like OR operation) on the first reproduced frequency-divided signal and the second reproduced frequency-divided signal reproduced from the recording medium to obtain a composite rectangular wave, and converts this composite rectangular wave into an FM signal. Demodulate to obtain a video signal.

(Function) In the method of the present invention, the first .
Since the second frequency-divided signal is recorded and reproduced, the carrier frequency of the FM modulated signal can be twice that of the conventional frequency, and the band of the information signal to be recorded and reproduced can be widened.

〔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 as shown in FIG. 2(A) is input to the terminal 10 and is supplied to the FM modulator 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 as shown in FIG. 2(B).

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.
It is a type flip-flop, and generates a first frequency-divided signal as shown in FIG. 2(C).

The 1/2 frequency divider 14 is a falling-trigger T-type flip-flop and generates the second frequency-divided signal shown in FIG. 2(D).

No. 1 above. The second frequency-divided signal is supplied to a laser diode driver (LDD) 16 in the optical pace 15, and the LD
By driving the laser diode (LD>17, the laser diode (LD>17 is the first laser diode with the intensity corresponding to the level of the first and second frequency divided signals, respectively).
．． 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 1'' 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.
Depending on the presence or absence of bits, first and second reproduced frequency-divided signals as shown in FIG.

The combining circuit 22 is an exclusive OR circuit, and the first . After performing an exclusive OR operation on the second reproduction frequency divided signal, a reproduction wave F shown in FIG.
Obtain M modulated signal @ (combined square wave). This reproduced FM modulated signal is demodulated by an FM demodulator 23 to obtain a video signal as shown in FIG. 2(A), and this video signal is outputted from a terminal 24.

In this way, since the first and second frequency-divided signals recorded on the disk 19 have a frequency that is 1/2 that of the FM modulated signal,
The carrier frequency can be raised to twice the upper limit frequency that was conventionally possible, thereby widening the band of the video signal.

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 one facing the rotating drum at a 180 degree position. Attach the two heads to the second head mounting position so that they are adjacent to each other in the direction of the rotation axis.
A head is required.

(Effect of the invention) As described above, according to the information signal recording and reproducing method of the present invention,
It is possible to widen the band of information signals such as video signals to be recorded and reproduced, and the quality of the reproduced video is improved, 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/reproducing device applying the method of the present invention, Fig. 2 is a waveform diagram for explaining the operation of the method of the present invention, and Fig. 3 is a frequency spectrum of an FM modulated signal. be. 11...FM modulator, 12...Limiter, 13°1
4...1/2 frequency divider, 19...disk, 22...
・Composition circuit, 23...FM demodulator 1゜Patent applicant: TIATSUKU Co., Ltd. Figure

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 synthesis circuit that performs an exclusive logic operation on the reproduced frequency-divided signal and the second reproduced frequency-divided signal to obtain a composite rectangular wave, the first and second reproduced frequency-divided signals are both transmitted to the recording medium. 1. An information signal recording and reproducing method characterized in that the synthesized rectangular wave is recorded on a FM signal, and the information signal is obtained by FM demodulating the synthesized rectangular wave.