JPS5858732B2 - Embankment Rokusai Seisouchi - Google Patents

Description

Detailed Description of the Invention The present invention irradiates a disc-shaped recording medium (hereinafter referred to as a recording disc) with a light beam such as a laser to record and reproduce FM signals of audio and video signals in a concentric spiral pattern. Regarding the equipment,
The purpose of this is to perform stable recording and reproduction by keeping the amount of optical energy absorbed by the recording medium constant at all recording points on the recording disk.

In a disc recording/reproducing device that optically records and reproduces signals on a disc-shaped recording medium, the spot diameter of the light beam irradiated onto the disc during recording is maintained in a uniform state, and the optical energy necessary for the disc to record is maintained. It is important to keep the amount of absorption constant.

However, in reality, when the record disk is rotating at a constant speed, the moving speed on the outer circumference of the record disk is different from the moving speed on the inner circumference.

That is, as recording progresses in the inner diameter direction, the moving speed at the recording point becomes slower.

Therefore, if the light beam irradiates the record disc with a constant energy, the amount of energy of the light beam absorbed by the record disc increases as the light beam advances in the inner diameter direction.

On the other hand, in order to uniformly record information on a recording disk, it is preferable that the amount of energy of the light beam absorbed by the recording disk changes little.

For example, when an amorphous material is coated on a recording disk as a recording medium, if the energy absorbed by the amorphous material is too large, the material will evaporate, and if the energy is too small, information will not be recorded reliably.

Therefore, when recording information while rotating the recorder at a constant speed,
It is desirable that the amount of energy of the light beam absorbed by the recording material be constant at all recording positions on the recording disk.

The present invention achieves the above-mentioned object by controlling the amount of irradiation energy of a light beam as the recording disk rotates and records are recorded in the inner diameter direction.

First, an outline of an optical disc recording/reproducing apparatus will be explained with reference to FIGS. 1a and 1b and FIG. 2.

Figure 2 is an enlarged view of the FM signal recorded on the record disc, with 22
is a recording track, and there is a low reflection area 2 in the light reflection area 23.
4 small bits 25 are arranged in a concentric spiral pattern and recorded.

The width n of the small bit 25 in the radial direction is constant, and information is recorded by changing the width W in the track direction.

Next, the configuration of the recording/reproducing apparatus will be explained with reference to FIG.

1 is a light beam generator, 2 is a light beam emitted from the light beam generator 1, 3 is an optical modulator for modulating the FM signal into an optical signal necessary for recording, and 4 is modulated by the optical modulator 3. 5 is a total reflection mirror, 6 is a light beam containing an FM signal, and
7 is a converging lens, and 7 is a recording disk, which is mounted on a turntable 8 made of a transparent material and rotated by a motor 9 at a constant speed.

Further, the turntable 8 and the motor 9 are moved one track at a time in the radial direction by the transfer shaft 10 each time the recording disk 7 rotates once.

The transfer shaft 10 is driven by a drive device 11 .

An example of the drive device 11 is shown in FIG.

In the figure, reference numeral 21 denotes a motor whose shaft center interlocks with a gear 20, and rotates the motor 21 so that the recording disk 7 moves one track each time it rotates.

Furthermore, in FIG. 1a, it is assumed that an FM signal including audio, video signals, etc. is supplied from the line 12.

13 is an amplifier, the FM signal is input to the optical modulator 3, modulates the optical beam 2 irradiated from the optical beam generator 1, becomes the optical beam 4, and passes through the total reflection mirror 5 and the converging lens 6. The recorder 7 is irradiated and recorded.

In the case of reproduction, the light beam 2 from the light beam generator 1
The light is irradiated onto the recording disk 7 via the total reflection mirror 5 and the converging lens 6 without being modulated.

The transmitted light 26 of the recording disc 1 is converted into an electric signal 15 by a photoelectric converter 14, and then passed through an amplifier 16 and a limiter 17 to the F.
Audio and video signals input to the M demodulator 18 and to be reproduced are extracted to a terminal 19.

In the recording method described above, as the recording track advances in the radial direction of the recording disk 70, the amount of optical energy absorbed by the recording disk 7 increases, and there is a possibility that the material of the recording disk 7 may evaporate.

In the present invention, by detecting the amount of movement of the recording disk 7 in the radial direction, for example, the amount of movement of the transport axis, and changing the pulse width of the electric signal input to the optical modulator 3 accordingly, the recording disk 7 is irradiated. The amount of light energy of the light beam 4 is changed.

Next, FIG. 3a shows an embodiment of the disc recording/reproducing apparatus according to the present invention.
, b.

In the figure, the same parts as in FIG. 1 are given the same reference numerals.

First, the amount of movement of the light beam 4 on the recording disk I necessary to control the energy amount of the light beam 4, which is the main part of the present invention, in other words, how much the turntable 8 and motor 9 are moved by the transfer shaft 10. The transfer amount detector 27 for detecting the amount of transfer will be explained with reference to FIG.

In the same figure, 10 is the transfer shaft already explained with reference to FIG. 1, and the gear 28 rotates as the transfer shaft 10 moves.

A variable capacitance element 29 whose capacitance changes with rotation is attached to the axis of the gear 28 .

In this way, a capacitance proportional to the amount of movement of the turntable 8 can be obtained.

Next, in FIG. 3a, 12 is an input terminal of the FM signal to be recorded, 31 is a differentiating circuit, which extracts leading and trailing edge signals of the FM signal, and a full-wave rectifier circuit 32 extracts the leading and trailing edge signals of positive polarity. Extract.

Waveform diagrams at this time are shown in Fig. 5, A22B and C.

33 is a monostable multivibrator, which operates in synchronization with the rise of the output signal from the full-wave rectifier circuit 32 mentioned above.

Since the output pulse width of the monostable multivibrator 33 can be changed depending on the resistance and capacitance that constitute it, the resistance value was set to an arbitrary value, and the capacitance was mounted on the aforementioned detector 27. Variable capacitance element 2
Using the capacitance obtained in step 9, the output pulse width of the monostable multi 33 is changed in accordance with the change in capacitance.

The output signal 34 of the monostable multi 33 is sent to the amplifier 3
5 to the optical modulator 3.

The signal input to the optical modulator 3 modulates the optical beam 2,
The signal is recorded on a recording disk 7 via a total reflection mirror 5 and a converging lens 6.

When recording in this way, for example, if the FM signal a in FIG. 5 is supplied to the line 12, since the recorder 7 is rotating at a constant speed, The moving speed at point, b point, and 0 point is from point a to point b, and from point b to 0.
The point moves slower.

Therefore, if we directly record the signal input from the line 12 at points a, b, and c, that is, the signal A in FIG. Although only a portion is irradiated, the actual irradiation time on the recording disk 7 becomes longer as the recording track advances toward the inner diameter, such as from point a to point b, from point b to point 0, and so on.

In other words, the amount of light energy absorbed by the material of the recording disk 7 is
The number increases as you get closer to the inner diameter.

When the input signal is constant as described above, there is a proportional relationship between the amount of movement of the recording track in the radial direction and the amount of optical energy absorbed by the recording material at the recording point at that time.

Therefore, if the irradiation time of the input signal light beam 4 is shortened in proportion to the amount of movement as the recording track moves toward the inner diameter, the amount of light energy absorbed at each recording point on the recording disk 7 can be made constant. .

In order to shorten the irradiation time, it is possible to shorten the width of the noise level of the input signal, but in the case of FM signals,
Since information is contained in the width of the signal, it is not possible to shorten only the width of the input signal, that is, the width of the 7-I level of the signal A in FIG.

Therefore, in the present invention, as described above, the FM signal 12 (c) is detected, the monostable multi 33 is activated in synchronization with the rising edge of the signal to create the recording signal 34, and the original FM signal is restored during playback. It is.

In this way, even if the width of the recording signal 34 (FIG. 5, 2) is changed, the information contained in the original FM signal 12 will not change.

Therefore, by reducing the variable capacitance in the detector 27 as the recording track moves toward the inner diameter, that is, in proportion to the amount of movement of the transport shaft, the output pulse width of the monostable multi 33 can be shortened.

The line 3γ connects the capacitance of the detector 27 to the monostable multi 33.

As an example, in FIG. 4, tracks a, recorded on the recording disk 7,
b and c, and waveform diagrams of the recording signal 34 at this time are shown in 2, ho, and h of FIG.

During reproduction, the light beam 2 emitted from the light beam generator 1 is directly irradiated onto the recording disc γ via the total reflection mirror 5 and the converging lens 6 without being modulated.

The transmitted light 26 at this time is detected by the photoelectric converter 14 and converted into an electrical signal.

The signal at this time is shown in FIG.

This signal is passed through the amplifier 16 to the flip-flop circuit 3.
Add to 8.

The Noritsubu flop circuit 38 receives the signal (
It operates at the rising edge of Fig. 5 h) and restores the FM signal.

The waveform at this time is shown in Figure 5.

Furthermore, the audio and video signals to be reproduced are extracted to a terminal 19 via a limiter 17 and added to an FM demodulation circuit 18 .

By performing recording and reproduction as described above, the amount of optical energy absorbed by the recording material can be kept constant no matter where the recording point is on the recording disk γ, and recording and reproduction can be performed stably. is possible.

In addition, in the example, an example was shown in which transmitted light was used for reproduction, but
It is also possible to implement the same method using reflected light.

[Brief explanation of the drawing]

Figure 1a is a block diagram showing the configuration of a conventional disc recording/reproducing device, Saikokusu is a perspective view of the drive unit for the transfer shaft used therein, Figure 2 is an enlarged view of recorded signals, and Figure 3a 1 is a block diagram of an embodiment of the present invention, the same figure is a perspective view of an example of a device for detecting the amount of movement of a transfer shaft, FIG. 4 is a plan view of a recording disk, and FIG. 5 is a detailed explanation of the present invention. FIG. 1...Light beam generator, 3...Light modulator, 7...Record disc, 12...FM signal input end, 27... ...Transfer amount detector, 33...
...”Mono stable multi.

Claims (1)

[Claims] A device for rotating a disk-shaped recording medium capable of recording an I FM signal in an optical form, a transfer device for moving a recording position in a radial direction as the disk-shaped recording medium rotates, a light beam generator, and a light beam. A disc-shaped recording and reproducing device comprising a device having a convergence device to record an FM signal on the disc-shaped recording medium, and a reproducing device including a photoelectric conversion device to receive the light beam from the light beam generator, Detecting leading and trailing edge signals of an FM signal to be recorded, recording the leading and trailing edge signals by pulse width control in a proportional relationship to the amount of movement of the phase shift device, and restoring the original FM signal from the pulse width control signal in a reproducing device. A disk recording and reproducing device characterized by: