JPS639033A - Track jump detector - Google Patents

Abstract

PURPOSE:To attain the improvement of an information processing speed and reliability by stopping the operation of a track jump detecting means during the generation of disturbance in a tracking control system or a prescribed period just after the generation of disturbance to suppress misdirection. CONSTITUTION:A recording period signal is sent from a modulating circuit 26 for outputting a signal to modulate a light source 3 in accordance with signals obtained from input terminals 24, 25 to a track jump detecting circuit 22 through a line 23. The circuit 22 neglects an output signal obtained from a window comparator 20 immediately after the start of recording and immediately after the end of recording, and in case of detecting the optical beam 4 scanning of an index area on the basis of an output signal of a gate circuit 21, neglects the output signal of the comparator 20 during the period and immediately after the period to prevent the generation of misdirection. In case of detecting track jump during recording, the circuit 22 sends a signal to a circuit 26 to stop recording and outputs a track jump signal to a control device through an output terminal 30.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention focuses and irradiates a light beam generated from a light source onto a record carrier, and performs tracking control so that the light beam on the record carrier always scans over a track. It relates to a device for recording or reproducing signals while recording or reproducing signals, especially when track skipping occurs while recording a signal on a record carrier or reproducing a signal recorded on a record carrier. This invention relates to a track jump detection device that detects this when the track jump occurs.

BACKGROUND ART An example of an invention related to this type of device is Japanese Patent Application Laid-open No. 1986-
There is one shown in Publication No. 11546.

This invention is configured to detect that a track skip has occurred in a light beam on a record carrier based on a signal from a track shift detection means, and to immediately reduce the light intensity of the light beam if a track skip occurs during recording. This is what I did.

Problems that the invention sought to solve In the conventional device described above, track skipping was detected only during recording, so if track skipping occurred just before recording, the signal was recorded in the wrong recording area and the signal was recorded in the wrong recording area. Already recorded signals may be damaged.

Furthermore, even if track skipping occurs during signal reproduction, this is not detected, so there is a problem in that an incorrect reproduction signal is sent out.

In order to solve the above-mentioned problem, if track skipping is detected even during playback, it is possible to detect track skipping by detecting track jumps during playback. Because of this structure, disturbances are likely to occur, and track skipping may be assumed to have occurred even though it has not occurred, significantly reducing the information processing speed of the device.

In view of this, the present invention aims to provide a highly reliable track jump detection device that does not reduce the information processing speed of the device.

Means for Solving the Problems The present invention provides a first area in which a signal is recorded in the form of unevenness and a first area in which the signal is recorded or a signal in a form different from that recorded in the first area. converting means for reproducing a signal recorded on the record carrier from a light beam reflected from or transmitted through the record carrier having a track constituted by a second recorded area; A moving means for moving the light beam irradiated onto the record carrier in the width direction of the track, and detecting a positional deviation between the light beam on the record carrier and the track from light reflected from the record carrier or transmitted light transmitted through the record carrier. tracking control means that controls the light beam on the record carrier to constantly scan the track by driving the moving means according to the signal from the track deviation detection means, and the scanning position of the conversion means A period detection means for detecting a period during which the period passes over the first region or a predetermined period immediately after passing the first region, and a signal of the control system of the tracking ff1i+) control means except for the period detected by the period detection means. It is constructed of a light beam on the record carrier and track jump detection means for detecting when the positional deviation of the track exceeds a predetermined value.

According to the above-described structure, even if a disturbance occurs in the tracking control system due to the address part of a track or sector, the track jump detection means does not operate during this period or a predetermined period immediately after, so that it is possible to detect that a track jump has occurred. No spurious signals are generated.

Example The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

A disk-shaped record carrier 1 having a spirally uneven track is fixed to a rotating shaft of a motor 2 and rotated at a predetermined rotational speed.

A light beam 4 generated from a light source 3 such as a semiconductor laser is converted into substantially parallel light by a coupling lens 6 and reflected by a polarizing beam splitter 6. The light beam 4 reflected by the polarizing beam splitter 6 passes through a λ/4 plate 7 (λ is the wavelength of the light beam 4), is focused by a converging lens 8 to a diameter of about 1 μm, and is irradiated onto the record carrier 1. . The reflected light 9 of the light beam 4 reflected by the record carrier 1 is passed through a converging lens 8. λ/
The light passes through the four plates 7 and the polarizing beam splitter 6, and is irradiated onto the photodetector 1o, which has a two-split structure.

The converging lens 8 is fixed to the movable part of the tracking element 11, and when a current is applied to the tracking element 11, the converging lens 8
is arranged to move approximately parallel to the plane of the record carrier 1 and in the radial direction, ie in the tracking direction.

Further, the light source 3, coupling lens 5, polarizing beam splitter 6, λ/4 plate 7, photodetector 10, and tracking element 11 are fixed to a transfer stage 12 so that they move together in the tracking direction. It is composed of

The two signals from the photodetector 1o are input to a differential amplifier 13, an adder circuit 14, and a signal processing circuit 15, respectively. The signal processing circuit 15 processes the two human input signals and outputs a reproduction signal of the signal recorded on the record carrier 1, respectively, according to the sum of the human input signals.

The photodetector 1o is installed so that the direction of the dividing line is the track direction on the photodetector 10, and the differential amplifier 13 generates a signal representing the positional deviation between the light beam 4 on the record carrier 1 and the track, that is, Outputs a track deviation signal.

The signals of the differential amplifier 13 and the adder circuit 14 are respectively input to a divider 16, and the divider 16 is connected to the differential amplifier 13.
A signal corresponding to the value obtained by dividing the signal by the signal from the adder circuit 14 is output. The signal from the divider 16 is applied to the tracking element 11 via a control circuit 17 and a drive circuit 18 for power amplification, and the tracking element 11 is configured such that the light beam 4 on the record carrier 1 constantly scans the track. Tracking is controlled as follows.

The record carrier 1 will be explained with reference to FIG. The figure shows a plan view of the record carrier 1, in which a spiral track 51 is cut from the outer circumference toward the inner circumference. The track 51 is divided into sectors 62 in which a predetermined amount of data can be recorded, and the sector 52 is composed of an index area 53 (hereinafter referred to as an ID area) for index storage and a recording area 54 for recording signals. . Example is 1
It shows that the circumferential track is divided into four sectors.

Figure B is an enlarged cross-sectional view of the record carrier 1 cut along the dashed line 55 shown in the λ diagram, 66 is a base having groove-like tracks on the surface of polycarbonate resin, etc., and 67 is the light beam 4.
The recording material layer 68 is a protective layer that protects the recording material layer.

To explain the detection of track skips in FIG. 1, the signal from the divider 16 is input to the window comparator 2o via a reduction pass filter 19 for reducing high-frequency noise. The window comparator 2o is in the Lot state when the input signal level vx is v1≧vx≧v2, and V
It is configured to be in a HIGH state when x>V or vx<v2. Here vl and v2 are the comparator levels of the window comparator, v, 〉v
It is 2.

As described above, the signal from the differential amplifier 13 represents the track deviation, and for example, if the amount of light beam 4 doubles, the output for a unit track deviation also doubles. However, since the signal from the divider 16 is divided by the signal from the adder circuit 14, it is not subject to fluctuations due to the light intensity of the light beam 4, changes in the reflectance of the record carrier 1, changes in the sensitivity of the photodetector 1o, etc. The output for a unit track deviation is constant. Therefore, even if the comparator level of the window comparator 2o is set to a constant value, the amount of track deviation to be detected is constant and stable detection can be performed.

The gate circuit 21 outputs a signal indicating the spread area 53 shown in FIG. 2 based on the signal from the signal processing circuit 16, and sends this signal to the track jump detection circuit 22.

The circuit configuration of the gate circuit 210 will be further explained with reference to FIG.

The signal of the signal processing circuit 15 is input to the pattern detection circuit 62 through the input terminal 61, and the pattern detection circuit 62
A special pattern recorded in the ID area 53 shown in the figure is detected and a pulse-like signal is sent to an AND gate 63.

When this signal is sent from the AND gate 63 to the mono staple multi vibrator 64 (hereinafter referred to as mono multi), the output of the mono multi vibrator 64 changes from HIGH to LOW.
state, and returns to the HIGH state after a predetermined period of time. The edge detection circuit 66 detects that the output of the monomulti 64 is f(IGH
It detects that the signal changes from the state to the LOW state, and turns this signal to O.
It is sent to the monomulti 67 via the R circuit 66.

The period of the ID area 63 shown in FIG. 2, that is, the period of the pulse signal of the pattern detection circuit 62 is T. , the period during which the pulse is input to the monomulti 64 and is in the LOW state is T1.
Then, To>T, and the configuration is such that even if a pseudo pulse is output to the pattern detection circuit 62 when the output of the monomulti 64 is in a LOW state, it will not malfunction.

The monomulti 6 end is a retriggerable monomulti, and is configured to always be in a HIGH state if a pulse is input at a predetermined cycle T2 (T2>To). The edge detection circuit 68 detects that the output of the monomulti 67 changes from a HIGH state to a LOW state, and sends this pulse signal to an OR circuit 66.

Therefore, even if the edge detection circuit 65 does not generate a pulse signal, two pulses are output to the OR circuit 66 at a cycle, so if there is a defect in the ID area 53 in FIG. 2, a pulse signal is output to the pattern detection circuit 62. OR circuit 66
An isometric pulse is output.

The period is T. The closer it is, the better, but since the record carrier 1 has rotational fluctuations, it is necessary to take this into consideration when setting.

The operation of the gate circuit 21 shown in FIG. 3 will be further explained with reference to the timing chart shown in FIG. 4.

A waveform is an input signal of the input terminal 61, and 71 indicates the period of the ID area 63 in FIG. 2, and 72 indicates the period of the recording area 540, respectively. ID area 63 is ID mark 7
It consists of 3 and an address signal.

Data 1.2 is recorded in each recording area of 2 people.
ing. Further, 74 indicates a pseudo ID mark, indicating that the ID mark of addressee 2 is missing.

Waveform B is the output waveform of the pattern detection circuit 62, waveform C is the output waveform of the monomulti 64, and waveform B is the output waveform of the edge detection circuit 65.
The output waveform of and the waveform E indicate the output waveform of the OR circuit 66, respectively.

As shown in waveform C, the pseudo ID mark 74 is removed from the output of the monomulti 64, and as shown in waveform E, the isometric ID mark 74 of the address person 2 is removed from the output of the OR circuit 66.
is interpolated.

The operation for preventing erroneous recording when track skipping occurs during recording will be explained with reference to FIG. 1.

24 is an input terminal for the recording period signal, 26 is an input terminal for the recording signal, 26 is a modulation circuit that outputs a signal for modulating the light source 3 according to the signals at the input terminals 24 and 25, and 27 is a signal of the modulation circuit 26. This is a drive circuit that drives the light source 3 according to the following.

A window comparator 2o detects that the light beam 4 on the record carrier 1 has skipped tracks.
Immediately after the start or end of recording, noise occurs in the output of the divider 16, and this noise causes the window comparator 20 to malfunction, outputting a pulse that assumes that a track jump has occurred even though it has not actually occurred. There is.

In order to prevent this false detection, the modulation circuit 26 sends the recording period signal to the track jump detection circuit 22 via the line 23.
The track jump detection circuit 22 detects the start and end of recording from this signal, and is configured to ignore the output signal of the window comparator 2o immediately after the start and end of recording.

This ignoring time is very short, for example 200 to 30
Since the time is approximately 0 μsec, track skipping will not occur within this time even if the device receives a large impact from the outside.

Furthermore, since the ID area 63 shown in FIG.
3, a disturbance may occur in the output of the divider 16 and the tracking control may be disturbed, and for this reason, a pulse that is considered to have occurred even though no track jump has occurred is sent to the window comparator 2o. It may be output. In order to prevent this false detection, the track jump detection circuit 22 detects that the light beam 4 is scanning over the ID area 63 from the output signal of the gate circuit 21, that is, the signal from the output terminal 69 in FIG. , the output signal of the window comparator 20 during and immediately after scanning the ID area 63 is ignored.

Furthermore, the track 51 on the record carrier 1 has a spiral shape, and if the tracking control is left in operation, the light beam 4 on the record carrier 1 will move from the outer circumference to the inner circumference. A still operation is performed to scan the image.

This methyl operation will be briefly explained. When a pulse indicating one rotation of the record carrier 1 is input to the input terminal 28, the control circuit 1 disables the tracking control, applies an acceleration pulse to the tracking 11, and moves the light beam 4 on the record carrier 1 in the outer circumferential direction. , after detecting that the vehicle is crossing the track and applying a deceleration pulse for braking to the tracking element 11, the tracking control is operated again to scan the same circumference.

This still operation naturally causes track skipping, but since it is performed forcibly, there is no need to detect it. The track jump detection circuit 22 is configured to detect from the control circuit 17 that the still operation is in progress, and to ignore the output signal of the window comparator 20 during this period.

The input terminal 29 is an input terminal that prevents track jump detection from being performed during an unnecessary period except for the recording period;
For example, the track jump detection circuit 22 is configured to input a signal indicating a signal read period and detect track jumps only during this period.

The operation when the track jump detection circuit 22 detects a track jump will be described below.

If a track jump is detected during recording, the track jump detection circuit 22 sends a signal to the modulation circuit 26 to immediately stop recording, and also informs the information processing control device controlling the device through the output terminal 3° of the track jump. Let me know what happened.

The information processing control device records a mark indicating invalidity in that sector and records the signal again in a new sector. If a track jump is still detected during playback, the track jump detection circuit 22 notifies the information processing control device through the output terminal 3° that a track jump has occurred. The information processing control device searches for the desired track again and reads the signal.

In this way, a reproduced signal with very high reliability can be obtained.

The configuration of the track jump detection circuit 22 will be explained with reference to FIG.

81 is an input terminal for the recording period signal inputted via the line 23 in FIG. This is the input terminal for the still operation period signal sent from the control circuit 17, and only during the still operation period is h
A signal that becomes the OW state is manually input.

85 is a delay circuit that delays the signal at the input end 81 for a predetermined time; 86 and 87 are inverting circuits that invert the delay circuit 85 and the signal at the input end 81; and 88 is a delay circuit that delays the signal at the input end 81 by a predetermined time. A monomulti 89 changes from a HIGH state to a Lot state and returns to a HIGH state after a predetermined time 3. 89 changes from a Low state to a HI state in synchronization with the fall of the monomulti 88
This is a mono multi-function device that enters the GH state and returns to the Lot state after a predetermined time T4.

Incidentally, the period T of the pulse signal of the pattern detection circuit 62 in FIG. The relationship between T3 and T4 is T, < T4 × T. It is set so that

9o is an oscillator that generates a rectangular wave signal of, for example, 10M11z, and 91 is a counting circuit.

The counting circuit 91 counts the pulse signals of the oscillator 90 when the input terminal 82 becomes HIGH, and when the counted value exceeds a predetermined value, the output becomes HIGH. Needless to say, when the input terminal 82 is in the LOW state, no counting operation is performed and the output is in the Lot state.

92 is a D-type 7 lip-flop, and the input terminal 82
When is in the Lot state, the output is in the LOW state, and when the input terminal 82 is in the HXC, H state and the output of the counting circuit 91 is in the HIGH state, the output is in the HIGH state.

Therefore, if there is a scratch on the record carrier, the window comparator 2
Even if a pulse signal is output at 0, if the time width of this pulse is shorter than T5, no signal is generated at the output of the flip-flop 92. However, T5 is the period of the oscillator 9o.
, where N is the count value required for the output of the counting circuit 91 to be in the HIGH state, T5=T6X'N. Matatade 5
is the time without track skipping, for example 200
It is set to be ~300 μsec or less.

The AND circuit 93 receives respective signals from the input terminal 81, the delay circuit 85, the flip-flop 92, and the monomultis 88 and 89, and outputs a signal corresponding to the logical product of these signals.

The signal at the output end 94 of the AND circuit 93 is input to an OR circuit 96 and the modulation circuit 26 shown in FIG. 26 and output end 3
o to the information processing control device.

II) The circuit 96 receives the signals from the inverting circuits 86, 87, the flip-flop 92, the monomultis 88, 89, and the input terminals 29 and 84, and outputs a signal according to the logical product of these signals. do.

The OR circuit 96 outputs a signal corresponding to the logical sum of the signals from the ND circuits 93 and 96.

The operation of the track jump detection circuit 22 will be explained with reference to the timing chart shown in FIG.

The waveform is the signal waveform of the signal processing circuit 15 in FIG. 1, waveform B.
is the signal waveform of the input terminal 83, that is, the gate circuit 21, waveform C is the signal waveform of the monomulti 88, and waveform C is the signal waveform of the monomulti 88.
Waveform E is the signal waveform of the input terminal 81, that is, the recording period signal waveform, waveform y is the signal waveform of the delay circuit 85, waveform G is the signal waveform of the low-pass filter 19 in FIG. The signal waveform of the window comparator 2o, the waveform J is the signal waveform of the flip-flop 92, the waveform J is the still operation period signal output from the input terminal 84, that is, the control circuit 17, the waveform is the signal waveform of the input terminal 29, and the waveform is the signal waveform of the input terminal 29. The signal waveform of the AND circuit 93 and waveform M are the signal waveforms of the OR circuit 95.

To explain the waveform G, 1o1 represents a track deviation when the tracking control is disturbed by the ID area 63, but the signals from the monomulti 88 and 89 cause the AND circuit and the OR circuit 95 to receive a signal representing a track skip. is not output.

102 represents a disturbance that occurs at the start of recording, and 103 represents a disturbance that occurs at the end of recording.
AND circuit 93 and OR circuit by the signal of input terminal 81
No signal indicating track skipping is output to the circuit 95. Reference numeral 104 indicates a case where a track skip occurs during recording, and when the AND circuit 93 sends information that a track skip has occurred to the modulation circuit 26 in FIG. 1, the modulation circuit 26 immediately closes the recording gate and stops recording. . 106 and 106 represent cases where track skipping occurs during playback. 1
When a track jump occurs as in 06, the input terminal 29 becomes L.
Since it is in the ot state, a signal indicating that a track skip has occurred is not output to the OR circuit 95, and when a track skip like 106 occurs, the input terminal 29 is in a HIGH state, so the OR circuit A signal indicating that track skipping has occurred is output to 95. 107 represents a track jump due to still jump, and the input terminal 84
Since the signal (waveform J) is in the LOW state indicating the still operation period, no signal indicating that a track skip has occurred is output to the OR circuit 95.

Further, 10B represents a disturbance caused by a scratch on the record carrier, and a pulse is output to the output of the window comparator 2o, that is, the waveform H, but the pulse width is greater than T5 to the output of the flip-flop 92, that is, the waveform H. It is too short to be output.

The gate circuit 21 shown in FIG. 1 can be configured as shown in FIG. Note that the same numbers are used for the same parts as in FIG. 3, and the explanation thereof will be omitted.

111 is a phase comparator, 112 is a low-pass filter, 1
13 is a voltage controlled oscillator that outputs a signal with a frequency corresponding to the input voltage.

The phase comparator 111 compares the phases of the signal from the edge detection circuit 65 and the signal from the voltage controlled oscillator 113, and outputs a signal according to the phase difference.

Since the signal of the phase comparator 111 is input to the voltage controlled oscillator 113 via the low-pass filter 11e, even if the In mark 73 shown in FIG. ID marks are interpolated.

As explained with reference to FIG. 3, although the ID mark may be missing in the output of the edge detection circuit 65, there is a low probability that a pseudo ID mark is included in the output of the edge detection circuit 65. By configuring the phase comparison to be performed only when a signal is output, it is possible to reduce the disturbance that occurs when the ID mark is missing, and the voltage controlled oscillator 113
The accuracy of the signal can be improved.

Although the present invention has been described in detail above, the present invention is not limited to the embodiments.

For example, although the configuration is such that the signal from the window comparator 2o is ignored during and before and after the ID area 63, it may be configured to ignore only the period immediately after the ID area 53.

Further, although the scanning of the light beam 4 over the XD region 63 is detected by the signal of the signal processing 16, it may be configured to be detected by the rotation of the motor 2.

Effects of the Invention By applying the present invention, even if tracking control is disturbed by the address part of a track or sector, a false signal indicating that track skipping has occurred will not be generated, thereby reducing the information processing speed of the device. It is possible to prevent this, and at the same time, it is possible to improve reliability.

[Brief explanation of the drawing]

1 is a block diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of the record carrier 1, FIG. 3 is a block diagram of the gate circuit 21, and FIG. 4 is a diagram for explaining the operation of the gate circuit 21. Timing chart, Figure 5 is track jump detection circuit 2
2, the block diagram of FIG. 6 is the track jump detection circuit 2.
7 is a block diagram of a simple embodiment of the gate circuit 21. FIG. 1...Record carrier, 3...Light source, 1o.
...Photodetector, 11...Tracking element, 16...Divider, 19...Low pass filter, 20...Window Comparator, 21...-gate circuit, 22...track jump detection circuit, 26... modulation circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Foil 4 Figure 5

Claims (4)

[Claims] (1) A first area in which a signal is recorded in the form of unevenness and a second area in which the signal is recorded in a form different from the signal recorded in the first area.
A device for recording a signal on a record carrier having a track consisting of an area, or for reproducing a recorded signal, using a light beam reflected from the record carrier or a light beam transmitted through the record carrier. a converting means for reproducing a signal recorded on the carrier; a moving means for moving a light beam irradiated onto the record carrier in the width direction of the track; and a positional deviation between the light beam on the record carrier and the track. track deviation detection means for detecting the light beam reflected from the record carrier or transmitted light transmitted through the record carrier; and the moving means is driven in accordance with a signal from the track deviation detection means so that the light beam on the record carrier is directed onto the track. tracking control means for controlling to always scan; and a period for detecting a period during which the scanning position of the conversion means passes over the first area or a predetermined period immediately after passing through the first area. a detection means, and a track jump detection means for detecting that the positional deviation between the light beam and the track on the record carrier exceeds a predetermined value from a signal from a control system of the tracking control means, excluding the detection period by the period detection means. A track jump detection device comprising: (2) The period detecting means is configured to detect a period during which the scanning position of the converting means passes over the first area or a predetermined period immediately after passing the first area from the signal of the converting means. A track jump detection device according to claim 1, characterized in that: (3) The first region is continuously detected from the signal of the conversion means, and when the second signal is not detected even after a predetermined period of time has passed after the first signal is detected, an alternative second region is detected. 3. The track jump detection device according to claim 2, wherein the device generates a signal and obtains a predetermined period from this signal. (4) a first detection means that continuously detects the first region from the signal of the conversion means; a voltage controlled oscillation means that changes the frequency of the output signal according to the input signal; Comparing means compares the phase of the signal and the signal of the voltage controlled oscillation means and generates a signal according to this phase difference,
3. The track jump detection device according to claim 2, wherein the period detection means is configured to control the voltage controlled oscillation means using the signal from the comparison means.