JPH0685223B2 - Track skip detector - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to recording by irradiating a light beam generated from a light source on a record carrier having a track for recording a signal or a track of a recorded signal. The present invention relates to an optical recording / reproducing apparatus for recording a signal on a record carrier or reproducing a signal recorded on a record carrier while performing tracking control so that a light beam on the carrier always scans a track. The present invention relates to a track jump detection device for detecting a track jump during recording of a signal on a record carrier or during reproduction of a signal recorded on a record carrier.

2. Description of the Related Art As an invention related to this type of device, for example, Japanese Patent Laid-Open No. 59-11
There is one disclosed in Japanese Patent No. 546.

The present invention is configured to detect that a light beam on a record carrier has caused a track jump from a signal of a track shift detection means, and to immediately reduce the light amount of the light beam when a track jump occurs during recording. It is the one.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the above-described conventional apparatus, if there is a scratch on the record carrier, the recording may be stopped assuming that the track skip has not occurred.

In the case of a record carrier which cannot be erased and recorded again after being recorded once, when the recording is stopped, the recording area cannot be used and the recording capacity is reduced.

Also, in the case of a record carrier that can be erased and recorded again in the same area, time for erasing and newly recording is required, which significantly reduces the information processing speed of the device.

In view of the above point, the present invention is to provide a track skip detection device having high reliability without reducing recording capacity and information processing speed.

Means for Solving the Problems The present invention relates to a converging means for converging and irradiating a light beam generated from a light source onto a record carrier, and a moving means for moving the light beam on the record carrier in the track width direction. Track deviation detecting means for detecting the positional deviation between the track on the record carrier and the light beam from the reflected light or transmitted light from the record carrier, and the light beam on the record carrier by driving the moving means in response to the signal of the track deviation detecting means. Tracking control means for controlling so that the track always scans the track, and comparator means for detecting that the positional deviation between the light beam on the record carrier and the track exceeds a predetermined value from the signal of the control system of the tracking control means. , A signal generating a signal indicating that the light beam on the record carrier has caused a track jump when the comparator means generates a signal exceeding a predetermined time width. And a jump jump detecting means.

With the above-described configuration, the present invention does not generate a signal in the track jump detection means if the signal is generated in the comparator means due to minute scratches on the record carrier and is shorter than the predetermined time width. Even if there are scratches on the record carrier, almost no pseudo signal indicating that a track jump has occurred is generated.

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

FIG. 1 is a block diagram of an embodiment of the present invention. A disk-shaped record carrier 1 having spiral irregular tracks is fixed to a rotation shaft of a motor 2 and is rotated at a predetermined rotation 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 5 and reflected by a polarization beam splitter 6. The light beam 4 reflected by the polarization beam splitter 6 passes through a λ / 4 plate 7 (λ is the wavelength of the light beam 4), is converged 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 convergent lens 8, λ / 4 plate
8, Passes through the polarization beam splitter 6, and is irradiated onto the photodetector 10 having a two-part structure.

The converging lens 8 is fixed to the movable part of the tracking element 11, and when a current is passed through the tracking element 11, the converging lens 8 is configured to move substantially parallel to the surface of the record carrier 1 and in the radial direction, that is, the tracking direction. There is.

Further, the light source 3, the coupling lens 5, the polarization beam splitter 6, the λ / 4 plate 7, the photodetector 10 and the tracking element 11 are fixed to the transfer table 12, and are configured to move integrally in the tracking direction. Has been done.

The two signals of the photodetector 10 are input to the differential amplifier 13, the adder circuit 14, and the signal processing circuit 15, respectively.
Is a signal corresponding to the difference between the two input signals, an adder circuit 14 is a signal corresponding to the sum of the two input signals, and a signal processing circuit 15 is a signal recorded on the record carrier 1 by processing the both input signals. Outputs each playback signal.

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

The signals of the differential amplifier 13 and the adder circuit 14 are respectively input to the divider 16, and the divider 16 outputs a signal corresponding to the value obtained by dividing the signal of the differential amplifier 13 by the signal of the adder circuit 14. . The signal of the divider 16 is applied to the tracking element 11 via a control circuit 17 and a drive circuit 18 for power amplification, the tracking element 11 being the light beam 4 on the record carrier 1.
Is controlled so that it always scans on the track.

The record carrier 1 will be described with reference to FIG. FIG. A shows a plan view of the record carrier 1, which is a spiral track.
51 is cut from the outer circumference to the inner circumference. The track 51 is divided into sectors 52 capable of recording a predetermined amount of data, and each sector 52 is composed of an index area 53 (hereinafter referred to as an ID area) for indexing and a recording area 54 for recording a signal. . The example shows that one track is divided into four sectors.

FIG. B is an enlarged cross-sectional view of the record carrier 1 taken along the alternate long and short dash line 56 shown in FIG. A, where 56 is a substrate having groove tracks on the surface of polycarbonate resin or the like, and 57 is changed by the heat of the light beam 4. The recording material layer 58 is a protective layer for protecting the recording material layer.

Describing the track skip detection in FIG. 1, the signal of the divider 16 is input to the window comparator 20 via the reduction pass filter 19 for reducing high frequency noise. The input signal level Vx of the window comparator 20 is
When V ₁ ≧ Vx ≧ V ₂ , it becomes LOW, and Vx> V ₁ or Vx <V ₂
It is configured to be in a HIGH state when. Where V ₁ and
V ₂ is the comparator level of the window comparator, and V ₁ > V ₂ .

As described above, the signal of the differential amplifier 13 represents a track deviation. For example, if the light amount of the four light beams doubles, the output for a unit track deviation also doubles. But the divider
Since the signal of 16 is divided by the signal of the adder circuit 14, it is not affected by the light quantity of the light beam 4, the reflectance change of the record carrier 1, the sensitivity change of the photodetector 10, etc. Is constant. Therefore, even if the comparator level of the window comparator 20 is set to a constant value, the track deviation amount to be detected becomes constant and stable detection can be performed.

The gate circuit 21 outputs a signal indicating the ID area 53 shown in FIG. 2 from the signal of the signal processing circuit 15, and sends this signal to the track jump detection circuit 22.

The circuit configuration of the gate circuit 21 will be further described 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 detects the special pattern recorded in the ID area 53 shown in FIG. Send to gate 63. When this signal is sent from the AND gate 63 to the monostable multivibrator 64 (hereinafter referred to as monomulti), the output of the monomulti 64 is
The HIGH state changes to the LOW state, and then the HIGH state again after a predetermined time. The output of mono-multi 64 is HI
Detecting the change from GH state to LOW state, OR this signal
It is sent to the monomulti 67 via the circuit 6.

53 cycles of the ID area shown in FIG. 2, that is, a pattern detection circuit
The period of 62 pulse signals T _0, and T ₁ a time period in which the pulse is in the input LOW state monostable multivibrator 64 are set to be T _0> T _1, the output of the multivibrator 64 Is LOW
In the state, even if a pseudo pulse is output to the pattern detection circuit 62, it does not malfunction.

The mono-multi 67 is a retriggerable mono-multi, and is always available if pulses are input at a predetermined cycle T ₂ (where T ₂ > T ₀ ).
It is configured to go high. Edge detection circuit
68 detects that the output of the monomulti 67 has changed from the HIGH state to the LOW state, and sends this pulse signal to the OR circuit 66.

Therefore, even when the pulse signal is not generated in the edge detection circuit 65, the pulse of the period T ₂ is output to the OR circuit 66, so that there is a defect in the ID area 53 of FIG. 2 and the pulse signal is output to the pattern detection circuit 62. Even if not performed, an equivalent pulse is output to the OR circuit 66.

The closer the period T ₂ is to T ₀ , the better, but since the record carrier 1 has rotational fluctuation, it is necessary to set this point.

The operation of the gate circuit 21 of FIG. 3 will be further described with the timing chart of FIG.

The waveform A is the input signal of the input terminal 61, 71 indicates the period of the ID area 53 in FIG. 2, and 72 indicates the period of the recording area 54. The ID area 53 is composed of an ID mark 73 and an address signal, and data is recorded in the recording areas of the addresses A ₀ and A _2.
1 and 2 are recorded respectively. Reference numeral 74 indicates a pseudo ID mark, indicating that the ID mark at address A ₂ is missing. The waveform B shows the output waveform of the pattern detection circuit 62, the waveform C shows the output waveform of the monomulti 64, the waveform D shows the output waveform of the edge detection circuit 65, and the waveform E shows the output waveform of the OR circuit 66.

As shown in waveform C, the output of Mono Multi 64 has a pseudo ID.
The mark 74 is removed and the equivalent ID mark 76 at address A ₂ is interpolated at the output of the OR circuit 66 as shown in waveform E.

The operation of preventing erroneous recording when a track jump occurs during recording will be described with reference to FIG.

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

The window comparator 20 detects that the light beam 4 on the record carrier 1 has caused a track jump. However, noise is generated in the output of the divider 16 immediately after the start or the end of recording, and the noise causes the window. The comparator 20 may malfunction, and a pulse considered to have occurred may actually be output even if track skipping does not actually occur.

In order to prevent this erroneous detection, the modulation circuit 26 sends a recording period signal to the track jump detection circuit 22 via the line 23, and the track jump detection circuit 22 detects the recording start and end from this signal, and immediately after the recording start and The output signal of the window comparator 20 immediately after the termination is configured to be ignored.

This time to ignore is very short, for example 200 to 300 μse
Since it is about c, no track jump occurs within this time even if the device receives a greater impact than the outside.

In addition, since an uneven signal is recorded in the ID area 53 shown in FIG. 2, a disturbance occurs in the output of the divider 16 while the light beam 4 on the record carrier 1 is passing through the ID area 53. Tracking control may be disturbed, which may cause a pulse to be output to the window comparator 20, which is considered to have occurred when no track jump has occurred. In order to prevent this erroneous detection, the track jump detection circuit 22 detects that the light beam 4 is scanning over the ID area 53 from the output signal of the gate circuit 21, that is, the signal of the output terminal 69 in FIG. , The output signal of the window comparator 20 immediately after and during the scanning of the ID area 53 is ignored.

Further, the track 51 on the record carrier 1 has a spiral shape, and if the track 51 is left with the tracking control activated, the light beam 4 on the record carrier 1 moves from the outer circumference to the inner circumference. Still operation is performed so as to scan.

This still operation will be briefly described. When a pulse indicating one rotation of the record carrier 1 is input to the input terminal 28, the control circuit 17
Disables the tracking control, applies an acceleration pulse to the tracking 11 to move the light beam 4 on the record carrier 1 in the outer peripheral direction, detects crossing of the track, and applies a deceleration pulse for braking to the tracking element 11. After that, the tracking control is operated again to scan the same circumference.

This still operation naturally causes a track jump, but since it is forcibly performed, it is not necessary to detect it. The track jump detection circuit 22 is configured so that the control circuit 17 detects that the still operation is in progress and ignores the output signal of the window comparator 20 during this period.

The input terminal 29 is an input terminal for preventing the track jump detection during an unnecessary period except the recording period.For example, a signal indicating a signal read period is input and the track jump is detected only during this period. The track jump detection circuit 22 is configured.

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

When a track jump is detected during recording, the track jump detection circuit 22 sends a signal to the modulation circuit 26 to immediately stop the recording, and a track jump occurs in the information processing control device controlling the device through the output terminal 30. Let us know. The information processing control device records a mark indicating invalidity in the sector and records the signal again in a new sector. When a track jump is detected during reproduction, the track jump detection circuit 22 informs the information processing control device through the output terminal 30 that the track jump has occurred. The information processing control device again searches for the desired track and reads the signal. In this way, it is possible to obtain a reproduced signal with extremely high reliability.

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

Reference numeral 81 is an input end of a recording period signal input via the line 23 in FIG. 1, 82 is an input end for inputting a signal of the window comparator 20, 83 is an input end for inputting a signal of the gate circuit 21,
Reference numeral 84 denotes an input terminal of a still operation period signal sent from the control circuit 17, to which a signal that is in the LOW state only during the still operation period is input.

85 is a delay circuit for delaying the signal of the input terminal 81 by a predetermined time,
86 and 87 are inverting circuits that invert the signals of the delay circuit 85 and the input terminal 81, and 88 is a mono-component that changes from the HIGH state to the LOW state in synchronization with the rising edge of the signal of the input terminal 83 and becomes the HIGH state again after a predetermined time T _3. Multi 89 is synchronized with the fall of Mono Multi 88
From LOW state to HIGH state, LOW again after a predetermined time T ₄
It is a state of mono-multi.

The period T ₀ of the pulse signal of the pattern detection circuit 62 of FIG.
And T ₃ and T ₄ are set such that T ₃ <T ₄ <T ₀ .

90 is an oscillator that generates a rectangular wave signal of 10 MHz, for example, and 91 is a counting circuit.

The counting circuit 91 counts the pulse signal of the oscillator 90 when the input terminal 82 is in the HIGH state, and the output is in the HIGH state when the counted value exceeds a predetermined value. Needless to say, when the input end 82 is in the LOW state, the counting operation is not performed and the output is in the LOW state.

92 is a D type flip-flop, and the input terminal 82 is LO
In the W state, the output is in the LOW state, and when the input terminal 82 is in the HIGH state and the output of the counting circuit 91 is in the HIGH state, the output is in the HIGH state.

Therefore, there are scratches on the record carrier and the window comparator 20
Even if a pulse signal is output to, the time width of this pulse is T ₅
If it is shorter, no signal is generated at the output of the flip-flop 92. However, T ₅ is the period of the oscillator 90, T ₆ and the counting circuit 91
If the count value required for the output of to become HIGH is N,
T ₅ = T ₆ × N. Further, T ₅ is set to a time at which no track jump occurs, for example, 200 to 300 μsec or less.

The AND circuit 93 has an input terminal 81, a delay circuit 85, a flip-flop 92,
The signals of the monomultis 88 and 89 are input, and a signal corresponding to the logical product of these signals is output.

The signal at the output terminal 94 of the AND circuit 93 is inputted to the OR circuit 95 and the modulation circuit 26 of FIG. 1, and when a track jump occurs after a predetermined time from the start of recording, the signal of the flip-flop 92 is modulated by the modulation circuit. The information processing control device is sent via 26 and the output terminal 30.

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

The OR circuit 95 outputs a signal corresponding to the logical sum of the signals of the AND circuits 93 and 96.

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

The waveform A is the signal waveform of the signal processing circuit 15 in FIG. 1, the waveform B is the signal waveform of the input terminal 83, that is, the gate circuit 21, the waveform C is the signal waveform of the mono-multi 88, and the waveform D is the signal waveform of the mono-multi 89. E is an input terminal 81, that is, a recording period signal waveform, waveform F is a signal waveform of the delay circuit 85, waveform G is a signal waveform of the low-pass filter 19 in FIG. 1, waveform H is an input terminal 82, that is, a signal waveform of the window comparator 20. , Waveform I is the signal waveform of the flip-flop 92, waveform J is the still operation period signal output from the input terminal 84, that is, the control circuit 17, waveform K is the signal waveform of the input terminal 29, waveform L is the signal waveform of the AND circuit 93, The waveform M is the signal waveform of the OR circuit 95.

Describing the waveform G, reference numeral 101 represents a track deviation when the tracking control is disturbed by the ID area 53, but the signals representing the track jump are given to the AND circuit 93 and the OR circuit 95 by the signals of the monomultis 88 and 89. Is not output. Reference numeral 102 represents a disturbance that occurs at the start of recording, and 103 represents a disturbance that occurs at the end of recording. However, due to the signals of the delay circuit 85 and the input terminal 81, the signal indicating the track skip is not output to the AND circuit 93 and the OR circuit 95. . 104 indicates the case where a track jump occurs during recording, and the AND circuit 9
When the information about the track skip is sent to the modulation circuit 26 of FIG. 1 from 3, the modulation circuit 26 immediately closes the recording gate and stops the recording. Reference numerals 105 and 106 represent the case where a track skip occurs during reproduction. When a track jump such as 105 occurs, the signal indicating that the track jump has occurred is not output to the OR circuit 95 because the input terminal 29 is in the LOW state,
When a track jump like 106 occurs, the input terminal 29 is HIGH.
Since it is in the state, a signal indicating that a track jump has occurred is output to the OR circuit 95. Reference numeral 107 represents a track jump due to a still jump. Since the signal (waveform J) at the input end 84 is in the LOW state indicating the still operation period, the signal indicating that the track jump has occurred is output to the OR circuit 95. Not done.

Reference numeral 108 represents a disturbance caused by scratches on the record carrier, and the output of the window comparator 20, that is, the waveform H.
The pulse width is shorter than T _5, but the pulse width is shorter than T ₅ because the pulse width is shorter than T ₅ .

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

For example, it is configured to ignore the signal of the window comparator 20 in the period of the ID area 53 and before and after the period,
It may be configured so that it is ignored only in the period immediately after the ID area 53.

Furthermore, although it is detected from the signal of the signal processing 15 that the light beam 4 is scanning over the ID area 53, it may be detected by the rotation of the motor 2.

EFFECTS OF THE INVENTION By applying the present invention, it is possible to eliminate a track skip signal that is artificially generated due to a scratch on a record carrier, etc., so that it is possible to prevent a decrease in recording capacity or a decrease in information processing speed of an apparatus, and Recording and reproduction can be performed efficiently.

[Brief description of drawings]

1 is a block diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of a record carrier, FIG. 3 is a block diagram of a gate circuit 21, and FIG. 4 is a timing for explaining the operation of the gate circuit 21. FIG. 5 is a block diagram of the track jump detection circuit 22, and FIG. 6 is a timing chart explaining the operation of the track jump detection circuit 22. 1 ... record carrier, 3 ... light source, 10 ... photodetector, 11 ...
Tracking element, 16-divider, 19-low pass filter, 20-window comparator, 21-gate circuit, 22-track jump detection circuit, 26-modulation circuit.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hiroyuki Yamaguchi 1006 Kadoma, Kadoma City, Osaka Prefecture, Matsushita Electric Industrial Co., Ltd. (72) Katsuya Watanabe, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A converging means for converging and irradiating a light beam generated by a light source onto a record carrier, a moving means for moving the light beam on the record carrier in the width direction of the track, and a track and a light on the record carrier. Track deviation detecting means for detecting the positional deviation of the beam from the reflected light from the record carrier or the transmitted light transmitted through the record carrier, and the moving means in response to the signal of the track deviation detecting means to drive the light on the record carrier. Comparing means for detecting that the positional deviation between the light beam on the record carrier and the track exceeds a predetermined value based on a signal from a tracking control means for controlling the beam to always scan the track and a control system of the tracking control means. And a signal indicating that the light beam on the record carrier has caused a track jump when the comparator means generates a signal exceeding a predetermined time width. Tracks characterized by having a track jump detecting means for raw skipping detecting device. 2. A track jump detecting means is configured to detect that the positional deviation between the light beam and the track on the record carrier exceeds a predetermined value from the signal level of the track deviation detecting means. The track jump detection device according to claim 1. 3. The positional deviation between the light beam on the record carrier and the track is a predetermined value from the level of the signal corresponding to the value obtained by dividing the signal of the track deviation detecting means by the signal corresponding to the light quantity of the reflected beam from the record carrier. The track jump detecting device according to claim 1, characterized in that the track jump detecting means is configured to detect that the track jump has been exceeded.