JPH0727648B2 - Track skip detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to irradiating a light beam generated by a light source on a record carrier having tracks for recording a signal,
The present invention relates to an optical recording / reproducing apparatus for recording by modulating the intensity of a light beam strongly and weakly while performing tracking control so that the light beam on a record carrier always scans a track. The present invention relates to a track jump detecting device that reduces the light quantity of a light beam when a track jump occurs during the operation, and prevents damage to a signal or the like already 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 device, the detection sensitivity of the track deviation detecting means changes due to the light amount of the light beam, the reflectance change of the record carrier, the sensitivity change of the photodetector, etc. It was difficult to perform high track skip detection.

Further, immediately after the start of recording, the light amount of the light beam suddenly increases, so that disturbance is likely to occur and it is considered that the disturbance has occurred even when the track skip has not occurred, and the recording may be stopped.

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 is directed to a moving means for moving a light beam irradiated on a record carrier in the width direction of a track, and a position shift between the track and the light beam on the record carrier from the record carrier. From the record carrier, track deviation detecting means for detecting from the reflected light, tracking control means for driving the moving means in response to the signal of the track deviation detecting means to control the light beam on the record carrier to be positioned on the track. Reflected light amount detecting means for detecting the amount of reflected light, a dividing means for outputting a signal corresponding to a value obtained by dividing the signal of the track deviation detecting means by the signal of the reflected light amount detecting means, and the light on the record carrier from the signal of the dividing means. And a track jump detecting means for detecting that the positional deviation between the beam and the track exceeds a predetermined value.

Further, the present invention provides a moving means for moving a light beam irradiated on a record carrier having a track for recording a signal in the width direction of the track, and a positional deviation between the track and the light beam on the record carrier. Track deviation detecting means for detecting from reflected light from the disk or transmitted light transmitted through the record carrier, and driving means for driving the moving means according to the signal of the track deviation detecting means so that the light beam on the record carrier is positioned on the track. Tracking control means for controlling, 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 based on the signal from the track deviation detection means, and the light quantity of the light beam from the reproduction light quantity. Also, when the signal of the track jump detection means is generated during the recording of the signal, the light amount of the light beam is immediately reduced to stop the recording. And a recording stop means for a predetermined period of recording immediately after the start of the signal is obtained not configured to stop recording also generates a track jump detection means signal.

Effect The present invention has the above-mentioned configuration and divides the signal of the track deviation detecting means by the signal corresponding to the amount of reflected light from the record carrier,
Since it is detected from the divided signal that the positional deviation between the light beam on the record carrier and the track exceeds a predetermined value, it is not affected by changes in the reflectance of the record carrier, changes in the light amount of the light beam, etc. It is possible to perform highly reliable and stable track skip detection.

Further, since the track jump detection means is configured not to stop the recording even if the signal is generated for a predetermined period immediately after the start of the signal recording, the positional deviation between the light beam and the track becomes a predetermined value immediately after the recording is started. Recording does not stop even if a pseudo signal indicating that it has exceeded is generated by the track jump detection means.

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 a converging lens 8 and a λ / 4 plate.
7. The light passes through the polarization beam splitter 6 and is irradiated onto the photodetector 10 having a two-divided 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 both input signals, the adder circuit 14 is a signal according to the sum of both input signals, and the signal processing circuit 15 is a signal recorded on the record carrier 1 by processing both input signals. Output the playback signals of.

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 55 shown in FIG. A, 56 is a substrate having groove tracks on the surface of polycarbonate resin, 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 , LOW state, 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 the track deviation. For example, if the light amount of the light beam 4 is doubled, the output for the unit track deviation is also doubled. However, since the signal of the divider 16 is divided by the signal of the adder circuit 14, the light amount of the light beam 4, the reflectance change of the record carrier 1, the photodetector 10
The output with respect to the unit track deviation is always constant without being affected by a change in the sensitivity of the above. 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 66.

53 cycles of the ID area shown in FIG. 2, that is, a pattern detection circuit
If the period of the pulse signal of 62 is T ₀ and the period in which the pulse is input to the monomulti 64 and is in the LOW state is T ₁ , then T ₀ > T ₁
Is set so that the output of Mono Multi 64 is LO.
In the W 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 addresses A0 and A2.
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 the 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 tracking control, applies an acceleration pulse to the tracking element 11 to move the light beam 4 on the record carrier 1 in the outer peripheral direction, detects crossing of the track, and sends a deceleration pulse for braking to the tracking element 11. After the addition, 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 that does not detect a track jump in an unnecessary period except the recording period. For example, a signal indicating a signal reading period is input and the track jump is detected only in 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 the recording period signal input through the line 23 in FIG. 1, 82 is a delay circuit for delaying the signal at the input end 81 by a predetermined time, and 83 is an input signal of the window comparator 20 in FIG. Input terminal for inputting the signal of the gate circuit 21, 85 is a mono-multi that changes from the HIGH state to the LOW state in synchronization with the rising edge of the signal of the input terminal 84, and becomes the HIGH state again after a predetermined time T ₃ , 86 is synchronized with the fall of Mono Multi 85
From LOW state to HIGH state, LOW again after a predetermined time T ₄
It is a state of mono-multi. The relationship between T ₀ , T ₃ , T ₄ is T ₃
It is set so that <T ₄ <T ₀ .

87 is an input terminal 81, a delay circuit 82, an input terminal 83, monomulti 85 and 8
It is an AND circuit that outputs a signal according to the logical product of each signal of 6. The signal from the output terminal 88 of the AND circuit 87 is input to the OR circuit 89 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 window comparator 20 is changed to the modulation circuit 26. And to the information processing control device via the output terminal 30.

90 and 91 are inverting circuits for inverting the signals of the input terminal 81 and the delay circuit 82.

The input terminal 92 is an input terminal for a still operation period signal sent from the control circuit 17, and receives a signal that is in the LOW state only during the still operation period.

Reference numeral 93 is an AN that outputs a signal corresponding to the logical product of the signals of the input terminal 83, the inverting circuits 90, 91, the monomultis 85, 86, and the input terminals 29,
The OR circuit 89 is a D circuit and outputs a signal corresponding to the logical sum of the signals of the AND circuits 87 and 93.

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 84, that is, the gate circuit 21, the waveform C is the signal waveform of mono-multi 85, the waveform D is the signal waveform of mono-multi 86, and the waveform. E is the input terminal 81, that is, the recording period signal waveform, waveform F is the signal waveform of the delay circuit 82, waveform G is the signal waveform of the reduction pass filter 19 of FIG. 1, waveform H is the input terminal 83, that is, the signal waveform of the window comparator 20, The waveform I is a still operation period signal output from the input terminal 92, that is, the control circuit 17,
The waveform J is the signal waveform of the input terminal 29, the waveform K is the signal waveform of the AND circuit 87, and the waveform L is the signal waveform of the OR circuit 89.

Describing the waveform G, 101 represents the track shift when the tracking control is disturbed by the ID area 53, but the signals representing the track jump are output to the AND circuits 87 and 93 by the signals of the monomultis 85 and 86. Not done. Ten
Reference numeral 2 denotes a disturbance generated at the start of recording, and 103 denotes a disturbance generated at the end of recording.
Due to the signal 81, the signal indicating the track skip is not output to the AND circuit 87 and the OR circuit 89. Reference numeral 104 denotes a case where a track jump occurs during recording. When the AND circuit 87 sends the information about the track jump to the modulation circuit 26 of FIG. 1, the modulation circuit 26 immediately closes the recording gate and stops recording. . Reference numerals 105 and 106 represent the case where a track skip occurs during reproduction. Input end 2 when 105 track jumps occur
Since 9 is in the LOW state, the signal indicating that a track jump has occurred is not output to the OR circuit 89, and when the track jump of 106 has occurred, the input terminal 29 is in the HIGH state, so the OR circuit A signal indicating that a track jump has occurred is output to 89. Reference numeral 107 indicates a track jump due to a still jump, and since the signal (waveform I) at the input end 92 is in the LOW state during the still operation period, the signal indicating that the track jump has occurred is not output to the OR circuit 89.

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.

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

EFFECTS OF THE INVENTION By applying the present invention, it is possible to perform extremely reliable and stable track skip detection that is not affected by changes in the reflectance of the record carrier, changes in the light amount of the light beam, and the like.

Further, since the track skip signal which is pseudo generated immediately after the start of recording can be removed, it is possible to prevent a decrease in recording capacity or a decrease in information processing speed of the apparatus, and it is possible to perform accurate and efficient recording.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of a record carrier 1, FIG. 3 is a block diagram of a gate circuit 21,
FIG. 4 is a timing chart 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 for 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.

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

Claims (2)

[Claims] 1. A moving means for moving a light beam irradiated on a record carrier in a track width direction, and a track shift for detecting a position shift between the track on the record carrier and the light beam from reflected light from the record carrier. Detecting means, tracking control means for driving the moving means in response to the signal from the track deviation detecting means to control the light beam on the record carrier to be positioned on the track, and detecting the amount of light reflected from the record carrier. Reflected light amount detecting means, dividing means for outputting a signal corresponding to a value obtained by dividing the signal of the track deviation detecting means by the signal of the reflected light amount detecting means, and a light beam on the record carrier from the signal of the dividing means. A track jump detection device comprising track jump detection means for detecting that a track position deviation exceeds a predetermined value. 2. A moving means for moving a light beam radiated on a record carrier having a track for recording a signal in the width direction of the track, and a position difference between the track and the light beam on the record carrier. Track deviation detecting means for detecting from reflected light from or transmitted light transmitted through the record carrier,
Tracking control means for driving the moving means according to the signal of the track deviation detecting means to control the light beam on the record carrier to be positioned on the track, and tracking control means on the record carrier from the signal of the track deviation detecting means. Track jump detection means for detecting that the positional deviation between the light beam and the track exceeds a predetermined value, and the track jump detection means during recording a signal by increasing the light quantity of the light beam above the reproduction light quantity. Recording stop means for immediately reducing the light amount of the light beam and stopping the recording when the signal is generated so that the recording is not stopped even if the track jump detecting means generates the signal for a predetermined period immediately after the start of the recording of the signal. A track jump detection device having the above-mentioned configuration.