JPS5817972B2 - Jiyouhoukirokuuchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for testing information such as video and audio signals on a disk coated with a photosensitive material at high density.

In recent years, information such as video signals and computer data has been converted into binary
The modulated data is modulated into a concave and convex shape and recorded on a disc-shaped recording medium, which is then used as a master to create numerous copies of the disc. Information is accurately transmitted from the copies of the disc using a light beam without contact. There are attempts to reproduce.

The problem with this attempt is how to reproduce recorded information in an orderly and accurate manner without contact.

For example, if a 30-minute television program is recorded in binary form on a disk with a diameter of 30 degrees rotating at 1800 rpm, the recording density will be extremely high, and the disk on which such recording is made It is extremely difficult to reproduce information in an orderly and accurate manner using a beam of light.

Specifically calculating the recording density assuming that the highest frequency of the video signal is 7 MHz, the radial width of the information groove is 0.92μ, and the gap between adjacent information grooves is 0.92μ.
This is clear from the fact that it is 92μ.

When recording information on a disk at high density and reproducing it, the recording system achieves high precision by carefully designing the mechanical accuracy of the disk rotation system and suppressing disturbances caused by disk eccentricity, motor vibration, etc. Although it is possible to perform high-density recording, it is not possible to suppress disturbances caused by disk eccentricity, motor vibration, etc. in the reproduction system due to cost considerations.

In the playback system, the eccentricity of the disk is usually about 200μ, and the rotation speed of the motor that rotates the disk is, for example, 30Hz.
(1800 r, p, m), disturbance vibration occurs up to three times that amount, that is, about 100 Hz.In this case, on a high-density disk, the speed is about 100 Hz, and if the track spacing of the information groove is 2 μ, then the disturbance vibration is 100 Hz. This will result in a discrepancy of approximately one book.

In other words, it is extremely difficult to reproduce information in a non-contact manner in an orderly and accurate manner using a light beam from a disc on which information is recorded at high density.

In order to accurately reproduce recorded information even in the presence of the above-mentioned disturbances and vibrations, the following method has been considered.

(For details, see the specification of Japanese Patent Application No. 12968-1973, "Information Recording and Reproducing Method and Apparatus" [filed on February 2, 1972])
Please refer to

) In order to perform accurate tracking during playback, the information signal to be recorded and played back is subjected to binary modulation such as FM modulation, pulse width modulation, pulse position modulation, etc. in addition to a standard signal for synchronization detection during recording. , intensity modulates the light beam for processing the recording medium by the modulated signal,
Information is recorded by irradiating the optical beam in a spiral manner onto a rotating disk while slightly vibrating it in the radial direction of the disk using a signal having the same frequency and phase as the standard signal for synchronization detection.

A large number of duplicate discs are created using the disc on which information has been recorded in this way as a master disc.

A method for accurately reproducing information from this duplicate disc will be described below.

First, the disk is rotated at a predetermined speed of 30 Hz, and an original beam of a laser or the like is irradiated along the information groove on the disk, and the reflected light or transmitted light (hereinafter collectively referred to as secondary light) is emitted.

) is converted into an electrical signal using photoelectric conversion means.

Then, the electric signal is demodulated and the above-mentioned standard signal for synchronization detection is extracted.

A tracking control signal is obtained by synchronously rectifying the envelope signal of the electrical signal using this standard signal for synchronous detection.

This tracking control signal indicates the amount and direction of the deviation in the disk radial direction between the center of the original beam and the vibration center line of the minutely vibrating information groove on the disk, so this signal is used. By deflecting the light beam in the direction opposite to the deviation, the light beam can accurately track the vibration center line J of the recorded information groove.

Finally, by extracting only the information signal from the demodulated signal of the electrical signal, the information can be accurately reproduced.

In the method described above, during recording, it is necessary to modulate the intensity of the light beam 4 and to deflect it with a signal having the same frequency and phase as the standard signal for synchronization detection.

In this case, due to the requirements of the tracking servo system during playback, the frequency of the standard signal for synchronization detection, that is, the deflection frequency of the light beam, is required in order for the light spot to accurately track the information groove on the video disc, which has a large amount of eccentricity. 30-100
It needs to be set to KHz.

It is impossible to obtain such a high deflection frequency using a mechanical method such as a galvanometer mirror.

As a deflector that can obtain a high deflection frequency, there is an AO deflector that applies ultrasonic light diffraction.

However, when using an AO deflector, it is difficult to match the phase of the standard signal for synchronization detection and the optical deflection.

Since the AO deflector applies ultrasonic light diffraction, there is time for the ultrasonic waves to travel to the point where light and ultrasonic waves interact.

In other words, there is a time lag between when a signal is input and when the light is actually deflected, and some means is required to compensate for this.

In order to overcome the above-mentioned problems, the present invention allows light deflection and light modulation to be performed by the same ultrasonic optical element.

In ultrasonic diffraction, the intensity of the diffracted light is determined by the amplitude of the ultrasonic wave, and the diffraction angle is determined by the frequency of the ultrasonic wave.

In other words, when vibration modulation and frequency modulation of ultrasound are performed at the same time, the light beam diffracted thereby undergoes intensity modulation,
and deflected.

According to the present invention, it is possible to easily match the phase of the synchronization detection signal and the optical deflection, which was a problem when the AO deflector was used independently of the optical modulator.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a disk, 2 is a center of rotation, and 3 is a t-polarized light-sensitive material coated on the disk surface, such as a photoresist that forms unevenness by irradiation with light, an emulsion (silver salt material) that forms shading, or M that causes magnetic changes
4 is an information groove, 5 is a light beam source, for example, an Ar laser that sensitizes a photoresist, Mn
6 is a light beam, 7 is a micro spot, 8 is a focusing optical system, 9 is a mirror, 10 is an ultrasonic light modulation deflector, 11 is an ultrasonic light modulation deflector, such as a He-Ne laser that changes the direction of the magnetic pole of B1. 12 is a modulated and deflected light beam, 13 is an addition and modulation means, 14° 14' is a modulation means, 15 is an information source, 16 is a standard signal generation means for synchronization detection, 17 18 is the output of the high frequency generator 11, and 19 is a standard signal for synchronization detection.

In addition, in the figure, the mechanism for rotating the disk 1 and moving the microspot 7 at a constant speed from the outer edge of the disk toward the rotation center 2 to form a spiral information groove is a well-known matter and is therefore omitted. do.

In this device, first, the information source 15 and the standard signal for synchronization detection are added.

In order to add them, it is desirable that the two signals be separated in frequency.

14 and 14' are modulation means for frequency-separating the two signals.

The signal 17 thus obtained is binary-modulated.

This binary-modulated signal enters a high frequency generator 11 which drives an ultrasonic light modulating deflector.

The high frequency wave 18 output from the high frequency generator 11 is amplitude-modulated by a signal 17 that is the sum of the information signal and the standard signal for synchronization detection, and is frequency-modulated by the signal 19 from the standard signal generation means for synchronization detection 16. .

The ultrasonic light modulation deflector 10 is a transducer (for example, ZnO1LiNb03) that converts an electrical signal into mechanical vibration.
etc.) and a medium (eg p b MO, TeO2, glass, etc.) through which the ultrasound waves are diffracted.

High frequency generator. The amplitude-modulated, frequency-modulated high-frequency electrical signal 18 outputted from 11 enters the ultrasonic light modulating deflector 10, where it is first converted into ultrasound by a transducer and then converted into a light beam in an ultrasound-light interaction medium. 6 is diffracted.

As a result, the light beam is subjected to an intensity modulation corresponding to the electric signal 17 and at the same time is deflected corresponding to the signal from the standard signal generating means 16 for synchronization detection.

The light beam 12 which has undergone intensity modulation and deflection is deflected by a mirror 9 and rotated by a focusing optical system 8.

The light is focused on the photosensitive material 3 on the disk 1, forming a spiral information groove 4 on the disk 1.

At this time, the information grooves are recorded in a spiral shape while slightly vibrating in the radial direction of the disk in accordance with the synchronization detection standard signal so that adjacent grooves do not overlap.

An example of details of the high frequency generator 11 is shown in FIG.

In the figure, 20 is an oscillator, 21 is a mixer, and 22 is an amplifier.

In order to modulate the oscillation frequency of the oscillator 20 with the synchronization detection standard signal 19, the oscillator 20 is configured with a Hartley circuit, and the capacitance of the capacitor that determines the time constant of the circuit is made variable, and is changed by the synchronization detection standard signal 19. etc., using conventional techniques.

Next, in the mixer 21, the frequency-modulated signal is amplitude-modulated with a binary-modulated signal 17 of the information signal and the standard signal for synchronization detection, and is appropriately amplified in the amplifier 22.

The output 18 is then input to the ultrasonic light modulation deflector 10.

As described above, according to the present invention described in detail, it is possible to match the phase of optical deflection with the standard signal for synchronization detection contained in intensity-modulated light, and it is possible to reproduce information from a disc in an orderly and accurate manner without contact.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the present invention, and FIG. 2 is a diagram showing an example of partial details of FIG. 1. In the figure, 1 is the disk, 2 is the rotation center of the disk,
3 is a photosensitive material, 4 is an information groove, 5 is a light beam source, 6
is a light beam, 7 is a micro spot, 8 is a focusing optical system, 9 is a mirror, 10 is an ultrasonic light modulation deflector, 11 is a high frequency generator, 12 is an intensity modulated and deflected light beam, 13 is a Addition modulation means, 14, 14' modulation means, 15 information source, 16 standard signal generation means for synchronization detection, 17 output of addition/modulation means 13, 18 output of high frequency generator 11, 1
9 is a standard signal for synchronization detection, 20 is an oscillator, 21 is a mixer, and 22 is an amplifier.

Claims (1)

[Claims] 1. An information source that generates an information signal to be recorded, a means for generating a standard signal for synchronization detection, and a means for frequency-separating the information signal and the standard signal for synchronization detection. first and second modulation means; and an adder that adds outputs from the first and second modulation means. a signal generating means for generating a signal amplitude modulated by the output from the adding means and frequency modulated by the synchronization detection standard signal; and an ultrasonic optical element to which the output from the signal generating means is applied. , a recording medium, and the ultrasonic light beam onto the recording medium. It is characterized by comprising a light beam irradiation means that irradiates through a wave optical element, and records the information signal and the synchronization detection signal by causing the light beam to vibrate minutely in a direction perpendicular to the direction in which information is formed. Information recording device.