JPS63834A - Optical recording carrier - Google Patents

Abstract

PURPOSE:To attain the reproduction or the recording of an information signal by specifying the refractive indexes and the thickness of a substrate and a protecting layer, in a recording carrier to make incident a light beam also from a protecting layer side. CONSTITUTION:On one plane of a base 64 made of a material having a refractive index of (n1) and having thickness of (d1), a groove 61, and a projecting part 62 are provided, and a thin film 63, and a protecting layer 141 are laminated on them, and the thickness (d2) of the layer 141 is formed around as (n1/n2)d1 with the material having a refractive index of (n2). In this case, it is preferable to set the thickness (d1) and (d2) in almost equal, and to form the base 64 and the layer 141 with the same material. In this way, it is possible to make incident the light beam both from a base 64 side, and a layer 141 side. Also, it is possible to reduce crosstalk by projecting on the groove 61, at the time of making incident the light beam from the base 64 side, and projecting on the projecting part 62, at the time of making incident the light beam from the layer 141 side.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical record carrier used in an optical reproducing device or an optical recording/reproducing device.

PRIOR ART A conventional optical record carrier comprises a substrate provided with information trunks on one surface, a thin film of at least 1M on the substrate, and an information track on the thin film or substrate. It was composed of a protective S layer for protection.

(Problems to be Solved by the Invention) The protective layer of a conventional record carrier is used to protect a thin film or base material from scratches, dirt, dust, etc., and is used to reproduce signals recorded on the record carrier. In this case, the light beam could only be incident from the base material side.

An object of the present invention is to provide an optical recording system capable of eliminating the above-mentioned conventional drawbacks, allowing a light beam to enter from the protective layer side, and improving recording density or retrieval speed of desired information. The purpose is to provide a carrier.

(Means for Solving the Problems) The optical record carrier of the present invention comprises a base material having a thickness of d and a light refractive index of nl, on one surface of which an information track is provided, and information on the base material. at least one provided on the track surface
It is composed of a thin film and a protective layer which is provided to cover the thin film and has a refractive index of light of n2 and a thickness of d2 of approximately n and d1.

(Function) When a light-transmitting material with a thickness of d, -=d is used as a protective layer, when a light beam is incident from the protective layer side, the aberration of the light beam on the information carrier surface of the base material is reduced. becomes less,
Information signals can be reproduced or recorded with the same high quality as when a light beam is incident from the base material side.

(Example) Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

Note that among the numbers used in the explanation of one drawing, the same numbers represent the same thing.

FIG. 1 shows an optical recording and reproducing apparatus suitable for reproducing information No. 1a recorded on the optical record carrier of the present invention or recording an information signal. Explain playback.

A disk-shaped recording medium 1 (hereinafter referred to as a recording disk) is connected to a motor 2.
The light beam 5 generated from a light source 4 (for example, a semiconductor laser) is made into parallel light by a coupling lens 6, and is sent to a converging lens 9 via a semi-transparent mirror 72 and a reflecting mirror 8. The light is incident on the recording disk 1 and focused on the recording disk 1. The reflected light 10 reflected by the recording disk 1 passes through the converging lens 92, the reflecting mirror 8, and the semi-transparent fi7 to the photodetector 11.
irradiated on top.

The recording disk 1 can be made of a resin or glass with concentric or spiral grooves and a recording material coated or vapor-deposited thereon. Explain things. To explain the recording disk 1 along with FIG. 2, (a) is a schematic plan view of the recording disk 1, (b) is an enlarged view of a part of the surface of the recording disk 1, and (c) is a diagram showing the recording disk 1 along the X axis. It is a partially enlarged view of a cross section when cut. 61 is a concentric groove;
62 is a convex portion between the grooves; 63 is a recording material coated or deposited on the recording disk 1; and 64 is a base material of the recording disk 1. The ratio of the widths of the grooves 61 and the protrusions 62 can be set arbitrarily, and signals can be recorded on both the grooves 61 and the protrusions 62. When recording a circular image signal, crosstalk occurs, so it is desirable to record on either the groove 61 or the convex part 62. In this case, the width of the groove 61 or the convex part 62 where the signal is recorded is It is desirable to make the width of the convex portion 62 or the groove 61 on which no signal is recorded wide. Further, when recording a digital signal for use in a document file or the like, since some crosstalk is allowed, it is possible to record signals on both the ridge 61 and the convex portion 62 with the same convergence. When recording signals on both the groove 61 and the convex part 62, the groove 61 and the convex part 62 are recorded from one direction.
However, for example, when the light beam 5 is irradiated from the base material 64 side and a signal is read using the reflected light 10, the reflected light 10 from the groove 61 is stronger than the reflected light 10 from the convex portion 62. It also has a large amount of light. Therefore, when reproducing the signal on the convex portion 62, the amount of crosstalk becomes large. Base material 64
When recording or reproducing a signal by entering the light beam 5 from the side, the groove 61 is irradiated, and the light beam 5 is entered from the side opposite to the base material 64 to record or reproduce a signal. In this case, if the convex portion 62 is irradiated,
Crosstalk can be reduced.

When recording a signal on the groove 61 and the convex part 62 from one direction, if the signal is modulated and recorded by means such as FM modulation, and the groove 61 and the convex part 62 are recorded in different frequency bands, it is possible to cross Talk can be reduced.

When the recording disk 1 is rotated by the motor 2, the concentric grooves 61 and the convex portions 62 cause eccentricity, so that the recording disk 1
It is necessary to perform control so that the upwardly focused light beam 5 tracks the groove 61 or the convex portion 62 (hereinafter this will be referred to as tracking control).

To explain this tracking control, in FIG. 1, the photodetector 11 has a two-divided structure, and the direction of the dividing line is the groove direction of the pattern of grooves 61 included in the reflected light 10 6 Therefore, A differential amplifier 12 obtains the difference between the respective outputs of the photodetectors 11.

This signal is transferred to switch 25. The reflecting mirror 8 is rotated via a compensation circuit 13 and a drive circuit 14 for compensating the phase of the tracking control system, and a direction substantially perpendicular to the groove direction on the recording disk 1 (approximately in the radial direction of the recording disk 1) is rotated. Tracking control is performed by driving an element 15 for scanning the light beam 5 that has been converged. Also.

The output of the differential amplifier 12 is connected to the switch 25. Compensation circuit 27
The transfer motor 29 is driven via the drive circuit 28 to transfer the transfer table 30 in the radial direction of the recording disk 1 (this is called transfer control). The relationship between tracking control and transfer control is such that tracking control corrects relatively high-speed track deviations such as eccentricity and vibration, and so that the element 15 rotates approximately in its natural state.
In other words, transfer control is performed so that the output of the drive circuit 14 becomes zero on average. The compensation circuit 27 is for compensating the phase of the five transfer control shifts. The transfer table 30 also has a light 'g4. Coupling lens 6, semi-transparent mirror 79 reflecting mirror 8. Converging lens9. Photodetector 11. A movable part 32 of a speed detector 31 that detects the moving speed of the element 15 and the transfer table 30 is attached, and is configured to move together with the transfer table 30. Speed detector 31 is possible
It consists of a section 32 and a fixed section 33, and magnetically detects the moving speed of the transfer table 30.

Reproduction number 44 is obtained by combining the respective outputs of the photodetectors 11 in a synthesis circuit 45, and this reproduction signal is input to an address extraction circuit 16 to extract address number a.
The information is input to the information processing control device 17. The addresses are 1 and 2 from the outer circumference of the recording disk 1 to the inner circumference (or from the inner circumference to the outer circumference).
,3. . . . However, the method of recording the address signal is already known and will not be described in detail.

Searching for a desired track will be explained. The track used in the explanation refers to the groove 61 or the protrusion 62 in which the signal is recorded when a signal is to be recorded only in either the groove 61 or the protrusion 62; When recording signals, both the grooves 61 and the protrusions 62 are called tracks. However, if the light beam 5 is incident from the base material 64 side and a signal is recorded in the groove 61, and the light beam 5 is incident from the side opposite to the base material 64 side and a signal is recorded in the convex portion 62, the base material 64 When the light beam 5 is incident from the side, the groove 61 is called a track, and when the light beam S is incident from the side opposite to the base material 64 side, the convex portion 62 is called a track.

When the address of the desired track is input to the address input device 18, the information processing control device 17 calculates the difference A2 between the address of the track where the light beam 5 is currently located and the address of the desired track.
is calculated and sent to the presettable up/down counter 19 to the preseller 1 through the line Q1, and a search start signal is sent to the flip-flop 20. Flip-flop 20 sends a signal to switches 21 and 22 and OR gate 23 to short circuit switches 21 and 22, and at the same time
Switch 25 is opened via gate 232 inverting circuit 24, opening the tracking control loop and the transport control loop. The output of the counter 19 is input to the DA converter 26, and the output of the DA converter 26 is input to the switch 2.
2 to the drive circuit 28 to drive the transfer motor 29 and move the transfer table 30. The transfer table 30 records the recording circle f
Moving in the radial direction of f1l, the light beam 5 focused on the recording disk 1 traverses the track. Immediately after the transfer platform 30 starts moving and immediately before it stops moving, the speed is slow, so it crosses the same track many times due to eccentricity or the like. If the eccentricity is expressed as A sin ω, then the speed of the trunk due to the eccentricity will be Aωcosωt, and the maximum speed will be Aω. A is the amplitude, ω is the angular frequency of the recording disk 1, and t is the time. When the movement ΔJ speed of the transfer platform 30 is greater than or equal to Aω, it will not cross the same track more than once, but when it is smaller than Aω, it may cross the same I-rack more than once, so simply count the trunks that cross it. If so, errors will occur due to duplicate counting. In order to eliminate this error, it is possible to detect the direction in which the light beam 5 converged on the recording disk 1 crosses the tracks so that the same track is not counted twice. 30 moves at high speed and the time to cross the track becomes short, direction detection becomes a national fortune. Detection of the cross-track direction is carried out by inputting the respective outputs of the photodetector 11 to waveform shaping circuits 34 and 35, respectively, and comparing the phases of the outputs of the waveform shaping circuits 34 and 35 with a phase comparator 36. For example, track pitch 2
11, if the speed of the transfer platform 30 is 1 m/sec, the time from one truck to the next is 2 μsec,
Furthermore, if the track width is 1 μm, the time to cross one track is 1 μsec. Since each output of the photodetector 11 is minute, it is necessary to amplify it, and this amplification must be a DC amplification. Furthermore, if the phase difference between the signals obtained by amplifying the respective outputs of the photodetectors 11 changes, it becomes impossible to detect the cross-track direction, and two amplifiers with the same frequency characteristics must be used. It is difficult to create two DC amplifiers with similar broadband characteristics, and the adjustment becomes complicated.

In order to eliminate such complicated adjustments, when the transfer table 30 is moving at high speed, the track-crossing direction is not detected, but the track-crossing signal is counted.

The signal of the speed detector 31 is input to the level detector 37,
When the speed of the transfer table 30 exceeds a certain constant speed v0, a signal is sent to the OR gate 38 and the inversion circuit 39.

This speed v0 is preferably set to v0≧Aω in consideration of eccentricity. Also, the level detector 37 sends a signal of the moving direction of the transfer table 30 to the OR gate 40. The output of the 1-inverting circuit 39 is sent to the OR gate 40. input, OR gates 38 and 4
The output of 0 is input to the AND gate 41. The output of the waveform shaping circuit 35 is inputted to the clock input terminal of the counter 19 via the delay circuit 42 and the switch 21, and
The output of the D gate 41 is the UP/DOWN of the counter 19.
It is input to the input terminal. Therefore, when the speed of the transfer table 30 is slow, the output of the level detector 37 is LOW, and the output of the inverting circuit 39 and OR gate 40 is HI.
GH, and the signal from the phase comparator 36 passes through the OR gate 38 and the AND gate 41 to the UP/D of the counter 19.
When the speed of the transfer table 30 is high, the output of the level detector 37 becomes HIGH, the output of the OR gate 38 becomes HIGH1, and the output of the inverting circuit 39 becomes LOW, and the output of the level detector 37 becomes HIGH. The moving direction signal is output from the OR gate 40. It is transmitted to the UP/DOWN input terminal of the counter 19 via the AND gate 41. The counter 19 performs counting according to the signals from the waveform shaping circuit 35 and the AND gate 41, and the output of the counter 19 is input to the coincidence detection circuit 43, and the minus number generation circuit 43 detects that it has come near the desired track. do. The level detector 372, phase comparator 36, etc. will be described in detail later. - The output of the output circuit 43 is input to the flip-flop 20, which opens the switches 21 and 22 and at the same time shorts the switch 25 through the OR gate 23 and the inverting circuit 24 to control tracking and transfer. multiply. The information processing control device 17 reads the address again, and if it matches the address of the desired track, ends the search (this search is called a coarse search); if it does not match, the address difference is If the absolute value of the address difference is greater than a certain value M (M is a positive integer), the coarse search described above is performed again, and if it is less than -a certain value M, a fine search is performed. . The fine search is performed by opening the tracking control and driving the element 15. The information processing control device 17 sends a signal indicating the address difference and its direction to the fine search circuit 44, and the fine search circuit 44 connects the OR gate 23. Then, the switch 25 is opened via the inversion circuit 24, and at the same time, a drive signal for fine search is sent to the drive circuit 14 to drive the probe 15.The fine search circuit 44 sends a termination signal to the line Q.
2 to the information processing control device 17, the information processing control device 17 reads the address again, and if it matches the address of the desired track, ends the search.

Next, detection of the cross-track direction will be explained with reference to FIG.

FIG. 3 is a simple representation of the waveform when the light beam 5 crosses the track, with time t on the horizontal axis.

(a) shows the recording disk 1, with grooves 61 on the base material 64.
The convex portions 62 and 62 are arranged at equal pitches, and the direction in which the light beam 5 crosses the track is in the opposite direction from the zero point. (b) and (c) are the respective outputs of the photodetector 11 when the light beam 5 is irradiated from the base material 64 side, (d) is the output of the differential amplifier 12, and (e) is the waveform. The output of the shaping circuit 35, (f) the output of the waveform shaping circuit 34, (g) the output of the phase comparator 36, and (h) the output of the delay circuit 42, respectively. The delay circuit 42
This is to prevent signals from being input to the P/DOWN input terminal and the clock input terminal at the same time. Phase comparator 3
6 can be composed of a D-TYPE flip-flop.

When using a two-person up/down counter for UP CLOCK and DOWN CLOCK, it may be configured as shown in FIG. That is, the 1-phase comparator 71 is composed of differentiating circuits 72 and 73 such as monostable multivibrators that generate a signal at the rising edge of an input signal, AND circuits 74 and 75, and an inverting circuit 76, and the outputs of the waveform shaping circuits 34 and 35 is input to the differentiating circuits 72 and 73, and the output of the waveform shaping circuit 34 and the output of the differentiating circuit 73 are input to the AND circuit 74.
The output of the waveform shaping circuit 35 is input to the inverting circuit 76, and the output of the inverting circuit 76 and the output of the differentiating circuit 72 are
The outputs of AND circuits 74 and 75 are input to the UP CLOCK and DOWN CLOCK input terminals. Also, without using the inverting circuit 76, the differentiating circuit 7
Counter 19.2 may be configured with a monostable multivibrator or the like that generates a signal at the falling edge of the input signal. D-A converter 26 and negative number output circuit 4
The configuration of No. 3 will be explained with reference to FIG. Now, if the address of the track where the light beam 5 is located is Y and the address of the desired track is 71, the information processing control device I7
, -Yl, and if Z knee Y engineering〉O, set this value to 2
The converted value is output to outputs D~DN-□, 1 is output to output D8 at the same time, a set command signal is sent through line Q, and counter 19 is preset. Also, if Zx Yt<0, output the two's complement of this value D
Output the output signal to the output line Q~D N-1, output O to the output line at the same time, send a set command signal through the line Q, and preset the counter 9. The D-A converter 26 is a D-A converter 26.
It is composed of a signal generator 81 that generates an A-converted signal and a differential amplifier 82. Signal generator 81 is counter 1
The outputs Q□~Q of 9 are input, and the counter 19
An analog signal corresponding to the signals of the outputs Q1 to Q is sent to the differential amplifier 82. At one input of the differential amplifier 82, the output Q of the counter 19 is 1 and the other output Q is 1 to QN-8.
A signal v equal to the output of the signal generator 81 when the total is zero
L is input, therefore, the output Q of counter I9
, is l and all other outputs are zero, the output of the differential amplifier 82 is configured to be zero. - Number configuration circuit 43
is an inverting circuit 83. for inverting the signal of the output Q)1 of the counter 19. It is composed of an N-input OR gate 84 and a differentiating circuit 85 such as a monostable multivibrator, and the output of the OR gate 84 becomes LOW when the outputs Q and I of the counter 19 are 1 and all other outputs are 0. Differentiator circuit 85 generates a signal when the output of OR gate 84 changes from a HIGH state to a LOW state, and transmits this signal to flip-flop 20.

For example, the track addresses are 1, 2, 3, etc. on the recording disk 1 from tracks on the outer circumference to tracks on the inner circumference.・
..., a signal is generated at the output of the differential amplifier 82 that causes the transfer table 30 to move from the outer circumference to the inner circumference of the recording disk 1 when Zl-Yl>0. , zl-y is 0, the opposite signal is generated.

Further, when the light beam 5 focused on the recording disk 1 crosses the track from the outer circumference to the inner circumference, the counter 19 performs addition, and when it crosses the track in the opposite direction, it performs subtraction.

The output of the D-A converter 26 generates a signal according to the output of the counter 19, and the absolute value of the output of the D-A converter 26 is the output Q. When the output Q is 1, the larger the binary number of the other outputs is, the larger the binary number of the other outputs is. If the output Q is zero, the smaller the binary numbers of the other outputs, the larger the output Q.

The level detector 37 includes a comparator '1' as shown in FIG.
1.93. It is composed of an inversion circuit 92 and an OR gate 94. The output of the speed detector 31 is input to a comparator 91 and an inverting circuit 92, the inverting circuit 92 inverts the output of the speed detector 31, and the comparator 91 detects that the output of the speed detector 31 has exceeded a certain value. If the comparator 9
3 generates a signal when the output of the inverting circuit 92 exceeds a certain value. The outputs of the comparators 91 and 93 are input to the OR gate 94. Therefore, the OR gate 94
The output of the speed detector 31 generates a signal when the absolute value of the output exceeds a certain value, and the OR as shown in FIG.
The signal is transmitted to the gate 38 and the inversion circuit 39. The moving direction of the transfer table 30 can be determined using the output of the comparator 91 or 93; for example, the output of the comparator 91 is input to the OR gate 40.

The moving direction of the transfer table 30 may be determined using the output QN of the counter 19.

Further, the moving direction of the transfer table 30 may be determined by storing the output DH of the information processing control device 17 in a flip-flop or the like, and using a signal from this flip-flop.

Alternatively, instead of using the speed detector 31, a differentiating circuit for detecting the differential coefficient of the output of the DA converter 26 may be provided, and the speed level signal and the moving direction may be detected from the output of this differentiating circuit.

When a video signal or the like is recorded on the recording disk 1 and a desired image or the like is retrieved, the output of the photodetector 11 shown in FIGS. 3(b) and 3(c) is affected by the recorded signal. Since video signals and the like have frequency fluctuations, for example, if they are recorded using FM modulation, the envelope of the reproduced signal will fluctuate due to the frequency fluctuations, making it difficult to detect the cross-track direction.

With the configuration shown in FIG. 7, extremely accurate track crossing direction can be detected. The respective outputs of the photodetector 11 are input to filters 101 and 102, and are also input to a combining circuit 45. The filters 101 and 102 are composed of low-pass filters, and reduce the reproduced signal and the envelope fluctuation component due to the frequency fluctuation of the reproduced signal, and prevent the truck from moving when the speed of the transfer platform 30 moves at a constant speed v0 or less. It is set to pass the track crossing signal output from the photodetector 11 which changes when the track is crossed. The outputs of the filters 101 and 102 are input to waveform shaping circuits 103 and 104, and the outputs of the waveform shaping circuits 103 and 104 are input to a phase comparator 36.
The output of the waveform shaping circuit 104 is connected to the switch 107. The output of the 0 synthesis circuit 45 is input to the filter 105. The output of the filter 105 is input to the waveform shaping circuit 106. The waveform shaping circuit 106 is connected to the switch 108. ing. The filter 105 is a low-pass filter that passes a higher frequency than the filters 101 and 102, and is set to pass the track crossing signal output from the photodetector 11 when the transfer platform 30 moves at the highest speed. . The waveform shaping circuits 103, 104, and 106 can have hysteresis, and the waveform shaping circuit 1
The hysteresis width of waveform shaping circuits 103 and 104 is made larger than that of waveform shaping circuits 103 and 104, and is configured to prevent malfunction even if some reproduced signal and envelope fluctuation components of the reproduced signal are superimposed on the output of waveform shaping circuit 106. There is. Therefore, the output of the waveform shaping circuit 106 generates a track crossing signal without malfunctioning with respect to the reproduced signal and the envelope fluctuation component due to the frequency fluctuation of the reproduced signal. The outputs of the switches 107 and 108 are connected to each other and input to a delay circuit 42, and the output of the delay circuit 42 is input to the clock input of the counter 19. O
The output of the phase comparator 36 and the speed level signal of the level detector 37 are input to the R gate 38, and the OR gate 40 receives the signal obtained by inverting the speed level signal of the level detector 37 by the inverting circuit 39 and the level detector. 37 movement direction signals are input. The outputs of the OR gates 38 and 40 are input to an AND gate 41, and the output of the AND gates 1-41 is input to the UP/DOWN input terminal of the counter 19.

The switch 107 operates according to the signal from the inverting circuit 39,
Switch 108 is configured to operate in response to a speed level signal from level detector 37.

The moving speed of the transfer table 30 is a certain constant speed V. , switch 108 is opened and switch 1
07 is shorted. Therefore, the clock input of the counter 19 receives the signal of the waveform shaping circuit 104 from the switch 1.
07 and the delay circuit 42. Transfer table 30
The moving speed of V is a certain constant.

In the above case, the switch 108 is short-circuited, and the switch 10
7 is in an open state, and the signal from the waveform shaping circuit 106 is transmitted to the clock input of the counter 19 via the switch 108 and the delay circuit 42. The signals input to the counter UP/DOWN input terminals due to the movement of the transfer table 30 are explained in FIG. 1 and will be omitted.

The output of the combining circuit 45 may not be input to the filter 105, but the output of either one of the photodetectors 11 may be input to the filter 105.

A light beam 5 is irradiated from the base material 64 side of the recording disk 1.

FIGS. 8 and 9 show the search for 1-rack when signals are recorded in both the groove 61 and the convex portion 62 and reproduced.

This will be explained with reference to FIG.

As shown in FIG. 3, when the optical beam 5 crosses the groove 61 and the convex portion 62, the output waveform (d) of the FII amplifier 12 is different from that when the optical beam 5 crosses the groove 61 if the traversal direction is the same. The polarity is opposite when crossing the convex portion 62.

Therefore, the polarities of the tracking control and the transfer control are also opposite, and when moving the light beam 5 from the groove 61 to the convex portion 62, the polarity of the tracking control and transfer control is changed.

In addition, it is necessary to detect the signal crossing the groove 61 and the convex portion 62 for the track crossing signal, and this signal is
It can be detected from the signals e) and (f). This will be explained with reference to FIG. 8. In FIG. 8(a), the outputs of the waveform shaping circuits 34 and 35 are input to a phase comparator 36, and further input to differentiating circuits 111 and 112. The differentiating circuits 111 and 112 are composed of monostable multivibrators and the like, and generate signals at the rising edge (or falling edge) of the output signals of the waveform shaping circuits 34 and 35. The OR gate 113 includes differentiating circuits 111 and 1.
12 outputs are input, therefore, OR gate 11
3 generates a signal when it crosses the groove 61 and the convex portion 62, and inputs the signal from the OR gate 113 to the delay circuit 42.
By inputting the signal from the delay circuit 42 to the clock input terminal of the counter 19 via the switch 21 (shown in FIG. 1), both the grooves 61 and the protrusions 62 traversed can be counted. Detection of the cross-track direction has been described in the explanation of FIG. 1, so a description thereof will be omitted. Further, even with the configuration as shown in FIG. 6(b), signals crossing the groove 61 and the convex portion 62 can be detected. That is, the outputs of the waveform shaping circuits 34 and 35 are connected to the clock input terminal and the D input terminal of a D-TYPE flip-flop for phase comparison, and at the same time, the output of the waveform shaping circuit 35 is input to the differentiating circuits 115 and 116. ing. The differentiating circuit 115 generates a signal at the rising edge of the signal from the waveform shaping circuit 35.

The differentiating circuit 116 generates a signal at the falling edge of the signal from the waveform shaping circuit 35. Therefore, the signal of the OR gate 117 to which the outputs of the differentiating circuits 115 and 116 are input is transmitted to the groove 61.
The grooves 61 and the protrusions 62 that have been crossed can also be counted by generating a signal when the grooves 61 and the protrusions 62 are crossed, and by counting the signals of this OR gate.

Next, detailed search will be explained using FIG. 9.

On the recording disk, grooves 61 and convex portions 62 are provided with 1.2, 3. They are numbered in order like... The address of the groove 61 is an odd number, and the address of the convex portion 62 is an even number (the reverse may also be possible, but this is assumed for the purpose of explanation).

The output of the differential amplifier 12 is connected to the switch 121 and the inverting circuit 1.
22, and the output of the inverting circuit 122 for inverting the polarity of tracking control and transfer control is connected to switch 12.
3 has nine inputs. The outputs of switches 121 and 123 are connected to each other and connected to compensation circuits 13 and 27, respectively. The switches 121 and 123 are never short-circuited at the same time, and one of them is short-circuited when tracking control and transfer control are applied. The polarity determining circuit 124 determines whether the switch 121 or the switch 123 is shorted. That is, No. 4a of the polarity determining circuit 124 determines whether tracking control and transfer control are applied to the groove 61 or the convex portion 62. Assume that when tracking control and transfer control are applied to the groove 61, the output of the polarity determining circuit 124 is HIGH and the switch 121 is short-circuited. When the address of a desired track is input to the address input device 18, the information processing control device 17 sends a signal indicating whether the desired track address is an odd number or an even number to the polarity determining circuit 124, and at the same time, the information processing control device 17 sends a signal indicating whether the desired track address is an odd number or an even number address to the polarity determining circuit 124. The difference A2 between the current track address and the desired track address is calculated, and when the absolute value of A is larger than a constant value M, the transport motor 29 is driven to perform a rough search, and -
If it is less than the fixed value M, the absolute value of Δ2 and a signal indicating the moving direction of the element 15 are sent to the fine search circuit 125. The fine search circuit 125 sends a signal for driving the cucumber 15 to the drive circuit 14,
At the same time, a fine search start signal is sent to the polarity determining circuit 124, and a LOW signal for opening tracking control and transfer control is sent to AND circuits 126 and 127. AND circuit 12
The outputs of switches 6 and 127 are LOW, switches 121 and 123 are both open, and element 15 rotates.

When the rope 15 rotates, the light beam 5 crosses the track,
The track crossing signal is sent to the synthesis circuit 45 and the waveform shaping circuit 1.
28, and the fine search circuit 125 is a waveform shaping circuit] A signal for counting the signals of 28 to detect that the light beam 5 has arrived on a desired track, and short-circuiting tracking control and transport control. AND circuits 126 and 127
send to When the output of the polarity determining circuit 124 is HIGH, the output of the AND circuit 126 becomes HIGH, and the switch 121 is short-circuited.

When the output of the polarity determining circuit 124 is LOW, the output of the inverting circuit 129 is HIGH, and the output of the AND circuit 127 is HIGH.
IGH, and the switch 123 is short-circuited.

As explained with reference to FIG. 2, if a detailed search is performed using a track-crossing signal and a track-crossing direction detection, the reliability will be further increased. The configuration of the polarity determining circuit 124 is as follows.
As shown in Figure 0, it consists of two D-TYPE flip-flops, and the D input terminal of the flip-flop 131 stores the lowest binary information of the desired track address, and the clock input terminal stores the lowest binary information of the desired track address. synchronization signals are input from the information processing control device 17, and the flip-flop 1
The Q output of the flip-flop 131 is input to the D input terminal of :32, the synchronization signal from the fine search circuit 125 is input to the tarok input terminal, and the Q output of the flip-flop 132 is input to the AND circuit 126 and the inverting circuit 129. input.

The synchronization signal from the fine search circuit 25 inputted to the clock input terminal of the flip-flop 132 may be generated between the start and end of the fine search, and of course may be generated at the same time as the start or at the same time as the end. If the output of the polarity determination circuit 124 generates a signal for determining the polarity of the tracking control and movement control of a desired track during the fine search, the fine search can be performed stably. This is extremely effective when a fine search is performed in synchronization with the rotation of the motor 2. Similarly, in the case of a coarse search, if the polarity of tracking control and transport control is determined during the coarse search period (including the start and end of the coarse search), a coarse search with high probability can be performed. The polarity of tracking control and transfer control is not determined using an address signal, but is determined by the difference between the address where the light beam 5 is located and the address of the desired track, that is, the number of tracks to be skipped during fine search or coarse search. You can also do that. That is, when skipping an odd number of tracks, the polarity may be reversed, and when skipping an even number, the polarity may be left unchanged.

Although the present invention has been explained above by dividing into coarse search and fine search and driving different elements, it is also possible to drive the same element.

Further, the moving speed of the transfer table 30 is detected, and when the moving speed is slow, the number of tracks crossed is counted using a track crossing signal and a truck crossing direction signal, and when the moving speed is fast, the moving direction of the transfer table 30 is counted. We have explained how to count the number of tracks crossed using the track crossing signal, but if the tracks are numbered and you are searching for a desired track, the address difference is the distance traveled, and the distance traveled is determined in advance. Therefore, the change in speed of the transfer table 30 can be determined. Therefore, the approximate speed of the transfer table 30 can be detected from the output of the counter 19, and the period during which the transfer table 30 moves by a certain distance r1 from the time when the transfer table 30 starts moving, and the period when the transfer table 30 moves from the desired track. The period from when a certain distance r2 is reached until a coincidence signal is generated is determined by counting the number of trucks crossed using a truck crossing signal and a truck crossing direction signal, and from when the transfer platform 30 has moved a distance r□. The number of trucks crossed may be counted based on the moving direction of the transfer table 30 and the trunk crossing signal until the distance r2 from the truck is reached.

FIG. 11 shows an optical record carrier according to an embodiment of the present invention, in which a light-transmitting protective layer is provided on the side opposite to the base material 64 side.

Tracking control is applied to the groove 61 when the light beam is incident on the base material 64 side for recording and reproduction, and when the light beam is incident on the side opposite to the base material 64 side for recording and reproduction, the convex portion 62 is In order to perform tracking control, the protective layer 141 should be made of the same material as the base material 64 and should have approximately the same thickness, thereby reducing lens aberration and narrowing the light beam 5. Base material 64 and protective layer 1
When the material of the base material 64 is different, the thickness of the base material 64 is d 1
If the refractive index of one light is n□, the thickness of the protective layer 141 is d x , and the refractive index of light is n2, then d 2 ""' d
The thickness of the protective layer 141 may be determined so that the thickness of the protective layer 141 is 1. Further, a space may be provided between the protective layer 141 and the base material 64.

The present invention is capable of detecting a track-crossing signal and a track-crossing direction from a playback signal not only on a grooved recording medium but also on a recording medium that has been subjected to gradation recording, uneven recording, evaporation recording, etc. Needless to say. Furthermore, the present invention can also be applied to a device that uses a magnetic material as a recording material, records or erases thermally, and reads signals using the Kerr effect or Faraday effect.

Further, the tracking method may be any method such as a three-beam method or a wobbling method.

(Effects of the Invention) The optical record carrier of the present invention is configured to read information signals recorded on the surface of the base material by inputting a light beam from the base material side and the protective layer side. In addition, the optical heads can be provided above and below the recording carrier, and it is possible to improve the information retrieval speed and the substantial information transfer speed.

By using the present invention, the device can be simplified and lowered in cost because no external scale is used, and furthermore, since the track crossing signal and the track crossing direction are detected,
This has the advantage of being able to search for a desired track with high precision and speed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an apparatus suitable for using the optical record carrier of the present invention, and FIG. 2 is a diagram showing the structure of a recording disk.
FIG. 3 is a timing chart for explaining detection of a track-crossing signal and a track-crossing direction signal;
The figure is a block diagram showing the circuit configuration when a two-person up-down counter is used, FIG. 5 is a configuration diagram of the D-A converter and the -number output circuit, and FIG. FIG. 7 is a block diagram showing another structure of the cross-track direction detection circuit. FIG. 8 is a cross-track signal and a cross-track signal when both grooves and convex portions are recorded on the track. FIG. 9 is a block diagram of the direction signal detection circuit, FIG. 9 is a circuit block diagram of the part that performs a fine search, FIG. 10 is a configuration diagram of the polarity determining circuit, and FIG.
FIG. 1 is a diagram showing the structure of an optical record carrier according to an embodiment of the present invention. 63... Recording material, 64... Base material, 141...
・Protective layer. Patent applicant Matsushita Electric Industrial Co., Ltd. Figure 2 ■ Figure 3 Figure 4 Figure 5 Figure 6 Figure 6

Claims (3)

[Claims] (1) Information tracks are provided on one surface and the thickness is d_
1, a base material having a light refractive index of n_1, and at least one thin film provided on the information track surface of the base material;
An optical record carrier comprising: a protective layer which is provided to cover the thin film and has a refractive index of light of n_2 and a thickness d_2 of approximately (n_1/n_2)d_1. (2) The optical record carrier according to claim (1), wherein the thickness d_1 of the base material and the thickness d_2 of the protective layer are approximately equal. (3) The optical record carrier according to claim (1), wherein the base material and the protective layer are made of the same material.