JPS60125937A - Optical information recording and reproducting device - Google Patents

Abstract

PURPOSE:To ensure the stability when address signals are read in the inner circumference of a disk by increasing the reproduction power toward the inner circumference of the disk. CONSTITUTION:A switch S performs switching between the voltage (j) supplied from a terminal H via a position detecting circuit and the voltage O used for setting the optional reproduction power. The contacts S0-S2 of the switch S are connected when an address signal section signal (n) is kept at an H level, and the potential at a point K is controlled by the voltage (j) given from the position detecting circuit and via a resistance R3 so that the reproduction power is decided by a transistor Q1 and a resistance R2. While the contacts S0-S1 are connected when the signal (n) is kept at an L level, and the voltage O decided by a resistance R6 is applied to point K. In such constitution, the reproduction power is controlled by the disk diameter as shown by (a) during an address signal section. While a fixed level of reproduction power is delivered except the address signal section as shown by (b).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention applies a semiconductor laser to a disc-shaped information recording carrier (hereinafter referred to as a disc) coated with a photosensitive recording material, as seen in the example of a video disc. The present invention relates to a device that records or reproduces information signals such as video signals and digital signals at a high density as irregularities or changes in shading by narrowing down a light beam such as the above to a minute light of about 1 μm.

Conventional Structures and Problems In recent years, optical video discs have become generally well known among the above-mentioned technologies as devices that only reproduce signals recorded in advance at high density.

Furthermore, the above-mentioned recording technology is used in an apparatus for making master discs of video discs.

Recently, optical information recording and reproducing apparatuses have been attracting attention, which record and reproduce information signals such as video signals, audio signals, and digital signals by applying the above-mentioned photosensitive recording material onto a disk.

In an optical information recording/reproducing device, a signal is recorded by irradiating the recording thin film of the disk with a laser beam or the like to melt and evaporate the light irradiated portion of the recording thin film, or by changing the reflectance or transmittance. Recording is done. That is, it is common practice to thermally utilize the energy of laser light to change the optical properties of a recording material.

The optical information recording/reproducing apparatus as described above will be explained below with reference to the drawings.

Figure 1 shows a conventional example of an optical information recording/reproducing device. In FIG. 1, a recording signal of an information signal such as a video signal or a digital signal is input to terminal A. Reference numeral 1 denotes a semiconductor laser drive circuit that drives a light source 2 such as a semiconductor laser that generates a light beam to be recorded on a disc. C surrounded by a dotted line indicates the optical head section and the semiconductor laser 2. Lens 3. Beam splitter for splitting the light beam 4. It is composed of a tracking mirror 6 for performing tracking control, a lens 6 incorporated in a voice coil or the like for performing focus control, etc., a lens 7 for converging reproduction light, and the like. Reference numeral 8 denotes a photoelectric converter for receiving reflected light from the disk 9 and converting it into an electric signal in order to obtain a reproduction signal. The disk e has concentric and spiral guide tracks 10.
A unique address signal is provided in advance for each guide track 10. Further, the disk 9 is rotated by a motor 11 at a constant speed of, for example, 1800 rpm. 13
is a transfer motor, which moves the disk 9 in the radial direction of the trunk by means of a transfer shaft 12.

14 is a preamplifier which amplifies the reproduction signal converted into an electric signal by the photoelectric converter 8 and outputs it from the output terminal B. Therefore, the address signal and the information signal recorded in the guide trunk are outputted to the terminal B as reproduction signals. A position detection circuit 16 detects the position of the optical head C in the radial direction of the disk 9. It is generally composed of a slide resistor, etc., and is generally used to correct the amplitude and frequency characteristics of the playback signal output from terminal B with respect to the disk diameter (not shown), depending on the output signal of the position detection circuit 16. It will be done.

Also, the address signal in the reproduced signal output from terminal B is read by an address reading circuit (not shown) consisting of a microcomputer, etc.
The address signal is read and the search and other controls of this device are controlled.

When recording with the above optical recording/reproducing device,
In the semiconductor laser drive circuit 1, the 13'C beam outputted from the semiconductor laser 2 is modulated by the intensity of the light using the recording signal inputted from the terminal A, and then outputted, and the optical head section C outputs the beam by 1 μm.
The disc 9 is irradiated with servo control such as focus control, tracking control, etc., which are generally known, and recording is performed. When reproducing, a weak light beam is output from the semiconductor laser 2 by the semiconductor laser drive circuit 1, and the focus is controlled in the same way as during recording.

The servo control such as tracking control is performed to irradiate the disk 9, and the reflected light is split by the beam splitter 4 and sent to the lens 7.
The photoelectric converter 8 receives the light through the photoelectric converter 8, amplifies it with the preamplifier 14, and outputs a reproduced signal such as an address signal or information signal from the output terminal B.

FIG. 2, FIG. 3, and FIG. 4 show configuration diagrams of the disk 9.

FIG. 2(C) shows a top view of the disk 9. FIG.

A concentric or spiral guide track 10 is provided on the disc 9 (FIG. 2 shows a concentric guide track as an example). Each guide track 1o is pre-formed with a unique address signal. Address signals are generally provided in order from the outer or inner circumference, such as address 1, address 2, address 3, etc. Recording is performed along the guide track 10, and an enlarged view of the recording pit is shown in FIG. 2(B). In FIG. 2(B), 1o is a guide track, and black dots d therein indicate examples of recording bits.

FIG. 3 shows a radial cross-section of the disc 9. The disk 9 is formed of a base member f forming a groove-shaped guide track and a recording surface q on which the above-described photosensitive recording material is applied. In addition, there is a protective layer etc. on the recording surface q (as shown in Figure 4).
is being processed.

10a, 10b, 100...1Qn indicates a guide trunk, and e indicates a groove. Each guide track 10
is width W (e.g. W = 0.8μ?7Z), pitch P (e.g. P = 2.5μ??+), depth σ (e.g. a-
0.7 μm). An example of pits recorded in the guide trunk is shown in 'ff:d.

Figure 4 (5) is a plan view of the guide track 10 (in Figure 4)
2 shows a cross-sectional view of the guide track 10 in the track direction. In the guide track 10, as shown in FIG. 4(f), an address signal section 20 in which a unique address signal etc. of the guide trunk 1Q recorded in advance at the time of forming the guide track, and information signals etc. are recorded. It consists of an information recording section 21 for The black dots d shown in the information recording section 21 indicate an example of recording bits as described above.

The guide track 10 is a groove-like structure having a depth σ as shown in FIG. There is. On the other hand, the information recording section 21 is a continuous groove-like structure having a depth σ, and the information signal is recorded in the form of shading. Fourth
In Figure (B), f is a base material portion, q is a recording surface coated with a photosensitive recording material, and h is a protective layer for protecting the recording surface from dust and scratches.

FIG. 6 shows an example of output characteristics when the semiconductor laser 2 is driven by the semiconductor laser drive circuit 1. The characteristic curve is the forward current (1) flowing through the semiconductor laser and the emission output power? )
shows the relationship between Forward current (I) is threshold current (I, h)
When the value exceeds , the laser light emission region is reached and a light emission output power approximately proportional to the current value is obtained.

FIG. 5(E) shows a recording signal inputted to the terminal in FIG. 1, and the recording signal causes a forward current (I) to be
(Ac) is modulated at the center. FIG. 4 (7) shows an example of the output light of the semiconductor laser 2 when the above modulation current (Ac) is input. The output power (PD) is the output power (PD) for the forward current, and the output power (PAC') is for the modulation current (Ac). In other words, as shown in FIG. 5(g), the semiconductor laser outputs a single beam of light modulated in the range of (PAc) around CP by the signal input to terminal A in FIG. Figure 5 At the output power of η (PP
) indicates peak power, and (PB) indicates bias power.

When recording, the output light of the semiconductor laser 2 is modulated by the recording signal as shown in FIG.
The light is narrowed down to a minute amount of light and irradiated onto the guide track 10 for recording.

When performing the next reproduction, a weak output reproduction power (PL) is output from the semiconductor laser 2 by the forward current (IL), and the light is narrowed down to a minute light by the optical head (q) and irradiated onto the guide track 1o. , the information signal in the address signal section 20 and the information recording section 21 is reproduced.The reproduction power is set to a weak optical output power that does not cause the photosensitive recording material to become in a recording state.

As described above, when a signal is recorded or reproduced on a disk that rotates at a constant rotational speed, the circumferential speed differs depending on, for example, whether the reproduction position is on the inner or outer circumference of the disk. In other words, the circumferential speed at the outer circumference is higher than that at the inner circumference because the radius is larger than the rotation center. It can be said that the length of the pit in the domestic IF field becomes longer due to the appearance of this J- or Todoroki (V'r Pi 1). The same can be said for the address signal of section 2° or the information signal recorded in the information recording section 21.As mentioned above, if the outer and inner circumferences of the disk have different peer lengths, As shown in FIGS. 6(A) and 6(B), the reproduced signal amplitude differs so that it is larger at the outer circumference than at the inner circumference. The sixth diagram is
- As an example, the reproduced signal amplitude of the address signal is shown in Figure 6 (B
) indicates the reproduced signal amplitude of the information signal recorded in the information recording section 21.

As mentioned above, address signals and information signals are transmitted to the inner circumference of the disk.
If a different signal amplitude is reproduced on the outer circumference, reading the address signal on the inner circumference becomes unstable.

It also affects the reproduction of information signals, for example, when recording and reproducing information signals such as video signals and digital signals,
This makes it impossible to faithfully transmit signals, which poses a major obstacle to the reliability of the optical information recording and reproducing apparatus as described above.

OBJECTS OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and provide an optical information recording/reproducing device that can faithfully reproduce signals.

Structure of the Invention The present invention provides a disk on which a guide track and an address signal unique to the guide track are provided in advance, and a
A light source such as a semiconductor laser that generates a light beam for recording and reproduction, an optical means that focuses the light beam as a minute light, and a servo that follows and focuses the minute light on the guide trunk of the disk: Ii control and a position detecting means for detecting a recording/reproducing position on the disk, and is configured to control regenerative power output from the light source such as the semiconductor laser based on an output signal from the position detecting means.

Description of examples The present invention will be described in detail below with reference to the drawings.

FIG. 7 shows an embodiment of the optical information recording/reproducing apparatus of the present invention. In FIG. 7, the same parts as in FIG. 1 are given the same numbers and detailed explanations will be omitted.

Terminal A is an input terminal into which a recording signal of an information signal such as a video signal or a digital signal is input. 3° is a semiconductor laser drive circuit for realizing the present invention, and C surrounded by a dotted line is an optical head section, which is composed of a semiconductor laser 2, a lens 3, a beam splinter 4, a tracking mirror 5, a lens 6, a lens 7, and the like.

8 is a photoelectric converter, 9 is a disk, 10 is a guide track,
11 is a motor, 12 is a transfer shaft, 13 is a transfer motor, 14
1 is a preamplifier, 15 is a position detection circuit, and terminal B is an output terminal for outputting a reproduction signal (including an address signal) from the disk 9.

The position detection circuit 15 is composed of a slide resistor and the like as described above, and outputs a voltage j corresponding to the disk diameter as shown in FIG. 8, and supplies it to the terminal H of the semiconductor laser drive circuit 1.

FIG. 9 shows an example of the configuration of the semiconductor laser drive circuit 3Q. LD indicates a semiconductor laser (FIG. 7, 2). In this semiconductor laser LD, a current I (contrary to I in FIG. 6) in the backward direction flows from the ground potential through the semiconductor laser LD, the resistor R6, the inductance, and the transistor Q2 toward the negative potential -■. flows.

The PD uses a photoelectric converter such as a solar cell, for example, to detect a portion of the output light of the semiconductor laser LD and generate a corresponding potential at a point. The photoelectric balancing resistor R4, the operational amplifier C1, and the transistor Q2 form a servo loop for controlling the reproduction power of the semiconductor laser LD and keeping its light emission output constant regardless of the temperature of the semiconductor laser LD. . The reference of the servo loop is determined by the potential at the point.

The transistor Q and the resistors R1, R2, and R3 change the potential at a point depending on the voltage j from the position detection circuit 16 inputted to the terminal H1. Therefore, the base voltage of the transistor Q2 changes and the forward current (same as in FIG. 6I) changes, thereby making it possible to control the reproducing power output from the semiconductor laser LD. Terminal A is an input terminal for recording information signals and the like. C1 is a coupling capacitor.

The reproduction signal amplitude of an address signal or a recorded information signal has a reproduction power characteristic that is proportional to the magnitude of the reproduction power as shown in FIG.

Therefore, as shown in FIG. 11, if the voltage j from the disk diameter position detection circuit 16 is controlled so that the reproduction power increases as the inner radius side is reproduced, the address signals and information signals on both the outer and inner circumferences are The reproduction signals can be made equal.

Another embodiment of the 15 raw power control method of the present invention is shown in the 12th embodiment.
As shown in the figure. FIG. 12 shows a configuration example of a semiconductor laser drive circuit 3Q for controlling the reproduction power only in the address signal section (address signal section 20 shown in FIG. 4). In FIG. 12, parts similar to those in FIG. 9 are designated by the same numerals, and detailed explanations are omitted.

In FIG. 12, 31 is a band amplifier circuit, 32 is a limiter circuit, and 33 is a retriggerable multi-by-break (hereinafter referred to as mono-multi), which constitutes an address signal section detection circuit. FIG. 13 shows a waveform diagram of the address signal section detection circuit, and the reproduced signal 2 from the preamplifier 14 is input to terminal B. FIG. 13 (phantom) shows a waveform diagram r of the address signal part in the reproduced signal.

The band amplification circuit 31 extracts only the address signal band of the reproduced signal °C, amplifies it, and sends it to the limiter circuit 32. The limiter circuit 32 shapes the waveform of the address signal as shown in the waveform diagram of FIG. The monomulti 33 is composed of nine triggerable multivibrators as described above, and by setting the time constant longer than the lowest frequency of the address signal frequency, the address signal section is divided into one pulse as shown in Fig. 13. become The pulsed address signal section signal (n) is input to a switch S comprising an analog switch or the like. The switch S switches between the voltage j from the position detection circuit 16, which is input from the terminal H, and the voltage O for setting an arbitrary reproduction power. Voltage O is determined by resistor R6. Further, when the address signal section signal (n) is at the "H" level, the switch S closes the contact 5O of the switch S.
-82 is connected, and the potential at the point is controlled by the voltage 1 from the position detection circuit 15 via the resistor R3 to the transistor Q1 and the resistor R2 to determine the reproduction power. Also, when the address signal section signal (nl) is at the "L" level, the contacts 5O-1-31 of the switch S are connected and a 4μ voltage determined by the resistor R6 is applied to the point. In the address signal section, as shown in Fig. 14 (a), the reproduction power is varied depending on the disc diameter, and in other than the address signal section, a constant reproduction power is output as shown in Fig. 14 (b)). I can do it.

The control of these reproducing powers is configured such that the control is performed within a range where the photosensitive recording material does not enter a recorded state even on the inner circumference.

Effects of the Invention According to the present invention, the address signal and recorded information are controlled so that the reproduction power increases as the inner circumference of the disc is reproduced only in the address signal section or even outside the address signal section. It is possible to make the reproduced signal width equal on the outer circumference and the inner circumference, and in particular, the address signal can be stably read on the inner circumference, which is highly effective.

In the past, an AGC circuit or the like was provided to correct the amplitude difference between the address signal and the reproduced signal between the inner and outer circumferences of the disk, but in the present invention, this circuit can be omitted and the effect is great.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an example of a conventional optical information recording/reproducing device, Fig. 2 (8) is a top view of the disk, Fig. 2 (B) is a partially enlarged view of the same disk, and Fig. 3 is the same as Fig. 2. 4 (B) is a sectional view of the guide track in the radial direction of the disk; FIG. 6 (B) is a sectional view of the guide track in the track direction; FIG. Diagram 6 is a reproduction signal characteristic diagram for address signal disk diameter, Figure 6 (
B) is a reproduction signal characteristic diagram of a reproduction signal such as an information signal depending on the disk diameter, FIG. 7 is a block diagram of an embodiment of the optical information recording/reproducing apparatus of the present invention, and FIG. 8 is an output voltage characteristic of a position detection circuit. Figure 9 is a circuit diagram showing an example of the configuration of a semiconductor laser drive circuit, Figure 10 is an amplitude characteristic diagram of address signals and information signals when reproduced with respect to reproduction power, and Figure 11 is reproduction power with respect to disk diameter. The output of! 12 is a circuit diagram showing a configuration example of a semiconductor laser drive circuit for controlling reproduction power only in the address signal section, FIG. 13 is a waveform diagram of the address signal section detection circuit, and FIG. FIG. 4 shows an output characteristic diagram of reproduction power with respect to disk diameter in the semiconductor laser drive circuit shown in the figure. 2... Semiconductor laser, 3, 6.7... Lens, 4... Beam splitter, 6... Tracking mirror, 9... Disc, 10...・
・Guide track, 11...Motor, 12...
・Transfer axis, 13...Transfer motor, 15...
...Position detection circuit, 30...Semiconductor laser drive circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3 Figure 4 (A) Figure 5 1l (E) To Rikishogo 6 Figure 7 Figure c Figure 8 Figure 9 Figure 10 Regeneration Power Figure 11 Figure 12 Figure 1, 1/ Figure 13 Figure 14

Claims (3)

[Claims] (1) A guide trunk and a disk on which an address signal specific to the guide track is pre-provided, a light source such as a semiconductor laser that generates a light beam for recording and reproducing on the disk, and a light source such as a semiconductor laser that focuses the light beam as a minute light. servo control means for following and converging the minute light on the guiding track of the disk, and position detection means for detecting the recording/reproducing position of the disk, and the output signal from the position detection means is used to detect the semiconductor An optical information recording/reproducing apparatus characterized by comprising means for controlling reproduction power output from a light source such as a laser. (2) The optical information recording and reproducing apparatus according to claim 1, wherein the means for controlling the reproduction power is controlled by the position detection means so that the reproduction power on the inner circumference side is larger than that on the outer circumference side. (3) The means for controlling the reproduction power includes an address signal interval detection means for detecting an address signal interval of the disc, and controls the reproduction power only in the address signal interval. Optical beta information recording and reproducing device.