JP3440574B2 - Optical disk drive - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to a least also handle recordable optical disc, an optical disc apparatus for detecting an off-track.

[0002]

2. Description of the Related Art Conventionally, as disc-shaped recording media, there are optical discs such as so-called compact discs (CD) and mini discs (MD: Mini Disc, trademark of Sony Corporation).

Among the above disc-shaped recording media,
For example, the MD is provided with a recordable / reproducible disc (recordable disc), a reproduction-only disc (premaster disc), a recordable recordable region in the disc, and a premaster region in which pits are preliminarily formed. There are discs (hybrid discs) and the like. In these various MDs as well, the basic parameters and recording density in optical recording are the same as those of CDs.

FIG. 9 shows an outline of the disc formats of the above three types of MDs. The premaster disc is shown in FIG. 9A and the recordable disc is shown in FIG. 9B. FIG. 9C schematically shows a cross section of the hybrid disc.

In these discs, the innermost peripheral portion of the information area is a lead-in area, and here, information for setting laser power called TOC (Table Of Contents) and discs are handled. Basic information is recorded as pit information. Further, the information areas other than the lead-in area at the innermost circumference of each of these discs are pit areas or recordable grooves depending on the characteristics of the disc such as the above-mentioned read-only and recordable / reproducible discs.

Further, the recordable disc shown in FIG. 9B will be described in more detail with reference to FIG. 10, and the disc has a radius of 30.5 mm and is divided into the lead-in area and the recordable area. The boundary is 16.0 mm from the center of disk rotation,
Further, the recordable area is 14.5 mm from the lead-in area to the outer peripheral side.

In the above recordable disc,
The recording groove on the entire circumference of the recordable area is AD when the disc is molded.
Cluster and sector address information called IP (ADdress In Pregroove) is formed by wobbling. Using this, not only the tracking and control of the CLV (constant linear velocity) spindle servo but also the system control including the access operation at the time of recording and reproduction is performed.
The ADIP signal is obtained by modulating a 22.05 kHz carrier with address information, and the recording groove meanders by about 30 nm with this carrier. The optical pickup can read the address information by the wobbling groove independently of the recording signal, and at the time of recording, recording is performed in cluster units based on the address information.

[0008]

By the way, the above-mentioned MD
In an optical disc device that handles an optical disc capable of writing information such as the above, for example, when an external shock is applied to the optical disc device while writing the above information, a beam spot on the optical disc is aimed. Off-track may occur off the track. When an off-track occurs due to the external impact while the information is being written in this way, there is a risk that the information already written on another track close to the target track may be destroyed.

In addition, it is difficult for the conventional optical disk device that handles the MD for music to detect whether or not the off-track is directly caused by an external impact due to the influence of defects on the optical disk, electric noise, and the like. It was

From the above, the MD for conventional music is used.
In the optical disc device that handles the above, a guard band for several tracks is provided between songs that form a group of music data, and the track crossing signal obtained by the beam spot crossing the tracks is monitored, Off-track due to impact is detected. Specifically, the number of pulses of the track crossing signal is, for example, 2
A method is adopted in which it is determined that the off-track due to an external impact has occurred only when the value exceeds the limit (that is, when the off-track for two tracks, for example).

However, in recent years, the above-mentioned MD optical disk has been used for recording / reproducing data other than music such as program data, video, and characters (hereinafter, this MD will be referred to as MD.
(Referred to as data) is required, and in this case, the group of data is smaller than the above music data, and therefore,
If the guard bands for several tracks as described above are provided, the recording capacity of the optical disk is wasted. Therefore, the same method as described above cannot be used as the method for the off-track determination.

Therefore, the present invention has been proposed in view of the above-mentioned circumstances, and an off-track can be performed accurately and in a short time regardless of the influence of a defect or electric noise on the disk without providing a guard band. It is an object of the present invention to provide a disc device capable of detecting the same and preventing the information already recorded on another track close to the target track from being destroyed.

[0013]

DISCLOSURE OF THE INVENTION The optical disk device of the present invention is proposed in order to achieve the above-mentioned object, and whether the magnitude of the tracking error is within a predetermined first range from the track center. A first off-track signal generating means for generating a first off-track signal, which indicates whether or not the signal is present, from the light amount detection signal; and a second off-track signal whose magnitude of tracking error is narrower than the first range from the track center. A second off-track signal generating means for generating from the tracking error signal a second off-track signal indicating whether or not it is within the range of Gate means for passing the first off-track signal only when the magnitude is in a state indicating that the magnitude is equal to or larger than the second range; The output from the gate means first
Shock-off signal for enabling the off-track detection operation when the state of the off-track signal changes and the magnitude of the tracking error changes from within the first range to above the first range. Latching means for latching the output of the latch means, and the output of the latch means is used as an off-track detection signal due to an external impact.

The optical disk device of the present invention also has a laser output switching means for switching the output of the laser oscillator between at least recording and reproducing, and if the off-track due to the external impact is detected during recording, The laser output switching means switches the output of the laser oscillator for reproduction.

[0015]

According to the present invention, when the second range is narrower than the first range with respect to the track center, for example, the first off-track signal and the second off-track signal are used. By detecting the off-track, the detection accuracy of the off-track above the first range is increased.

Further, according to the present invention, if an off-track due to an external impact is detected at the time of recording, the output of the laser oscillator is switched to the reproducing mode so that the tracks other than the target track are irradiated with the laser beam. , The already recorded data will not be destroyed.

[0017]

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

FIG. 1 shows a schematic structure of a disk device of the present invention.

First, prior to the description of off-track detection due to an external impact performed in the optical disk device of the embodiment of the present invention, the overall configuration and operation of the device of the present embodiment will be described.

That is, in the optical disk device shown in FIG. 1, first, as a recording medium, a magneto-optical disk 2 such as the recordable MD which is rotationally driven by a spindle motor 9 is used. Here, the magneto-optical disc 2 is used for recording / reproducing data other than music such as program data, video, and characters (disc for MD data). Therefore, since the group of data recorded on the disc 2 is finer than the music data and the recording capacity of the disc is effectively used, the apparatus of the present embodiment is arranged so that each disc has the same music data as the above-mentioned disc for music data. A guard band for several tracks will not be provided.

The optical pickup 4 is composed of, for example, a laser light source such as a laser diode, a collimator lens, an objective lens 3, optical components such as a polarizing beam splitter and a cylindrical lens, and a photodetector having a light receiving portion of a predetermined pattern. . The photodetector corresponds to a sub-spot in addition to a so-called four-division photodetector corresponding to the 0th order light of the main spot and two photodetectors corresponding to ± 1st order light used in a normal CD reproducing apparatus. Two photodetectors are provided. The objective lens 3 is driven by a biaxial actuator, and the optical pickup 4 is movable in the radial direction of the magneto-optical disk 2 by a stepping motor 10.

The optical pickup 4 is provided at a position facing the recording magnetic head 1 with the magneto-optical disk 2 in between. When data is recorded on the magneto-optical disk 2, the recording magnetic head 1 is driven by an OWH (overwrite head) driver (write driver) 5 which is a head driving circuit of a recording system, and a modulation magnetic field according to the recording data is generated by the optical signal. While applying to the recording surface of the magnetic disk 2,
By irradiating the target track of the magneto-optical disk 2 with laser light of a predetermined power (recording power) through the objective lens 3 by the optical pickup 4, thermomagnetic recording by a so-called magnetic field modulation method is performed.

At the time of this recording, the data to be recorded is SC
It is supplied from, for example, a host computer or the outside through an SI (small computer systems interface) controller 24 and a terminal 35. The data supplied via the terminal 35 and the SCSI controller 24 is an MD / ECC encoder / decoder that performs addition and error correction processing of a buffer memory controller unit that controls the dynamic RAM 22 as a buffer memory and an error correction code for MD. The RAM 22 via the control IC 21 including
After being temporarily stored in, the signal is read out and sent to the encoder of the signal processing circuit 6.

The control IC 21, the SCSI controller 24, and the system controller 15 are connected to the ROM (read only memory) 2 via a bus.
Various control operations are performed based on the program data stored in 3.

RAM as the buffer memory
The reference numeral 22 also functions as a shock-proof memory for accumulating data for the time required to return to a desired track when tracking of the optical pickup 4 is lost due to a shock or the like during recording or reproduction.

The signal processing circuit 6 adds an error correction code and 8-14 modulation (EFM) to the data to be recorded and converts it into a recording signal. This recording signal is sent to the OWH driver 5, and the driver 5 drives the recording magnetic head 1 according to the recording signal. At the same time, the optical pickup 4 is operated by the PWM
(Pulse width modulation) The driver 12 controls the laser light to have recording power, which raises the temperature of the recording surface of the recording track to the so-called Curie point.

At the time of reproduction, the recording track of the magneto-optical disk 2 is traced by the laser light by the optical pickup 4 to perform magneto-optical reproduction utilizing the so-called Kerr effect.

The optical pickup 4 detects the reflected light of the laser light applied to the target track and sends this detection signal to the RF amplifier 8. This detection signal includes a reproduction signal corresponding to the difference in the polarization angle (Kerr rotation angle) of the reflected light of the laser beam from the target track during reproduction, and a focus error signal during recording and reproduction, for example, by the so-called astigmatism method. And a tracking error signal by a so-called push-pull method, and address information by the wobbling groove used at the time of recording.

When reproducing data from the magneto-optical disk 2, the RF amplifier 8 extracts the reproduction signal from the output signal of the optical pickup 4 and sends it to the signal processing circuit 6. At this time, the signal processing circuit 6 obtains reproduced data by performing demodulation of the EFM and error correction processing on the reproduced signal by the decoder section. Further, the RF amplifier 8 also includes respective components for off-track detection due to an external impact of this embodiment described later.

The reproduced data via the RF amplifier 8 is
The data is temporarily stored in the RAM 22 via the control IC 21 and then read out, and sent to the host computer or the like via the SCSI controller 24.

When the data read from the magneto-optical disk 2 is compression-encoded audio data in MD format, the control IC is used.
The compressed audio data from 21 is expanded and decoded by the expansion and decoding circuit 31 and then digital / digital
The analog conversion circuit 32 converts the analog audio signal. This analog audio signal is sent to the external line connection terminal via the line amplifier 33 and the terminal 36, or to the headphone connection terminal via the headphone amplifier 34 and the terminal 37.

As compression encoding of the audio data, the so-called ATRAC (trademark of Sony Corporation, Adaptive, which is adopted in the MD format and which compresses the information amount to about ⅕ in consideration of human auditory characteristics. TRansform A
A method called coustic coding is used. Although not shown, the apparatus of this embodiment also has a configuration in which, when an audio signal is supplied, it is compression-encoded and recorded on the MD disc 2.

The RF amplifier 8 extracts the focus error signal and the tracking error signal from the output signal of the optical pickup 4 during recording and reproduction, and sends these error signals to the servo circuit 13.

The servo circuit 13 uses the focus error signal and the tracking error signal read by the optical pickup 4 to generate a focus servo signal and a tracking servo signal, and these servo signals are passed through the PWM driver 12. Optical pickup 4
Send to. As a result, focus servo and tracking servo are performed in the optical pickup 4. That is,
For the focus servo, focus control of the optical system of the optical pickup 4 is performed so that the focus error signal becomes zero. Further, for the tracking servo, tracking control of the optical system of the optical pickup 4 is performed so that the tracking error signal becomes zero.

Further, the servo circuit 13 has a structure for the rotary servo of the spindle motor 9 for rotating the magneto-optical disk 2 in addition to the structure for the focus servo and the structure for the tracking servo described above. is doing. That is, the servo circuit 13 of the spindle motor 9 drives the spindle motor 9 so as to rotate the magneto-optical disk 2 at a predetermined rotation speed (for example, a constant linear velocity: CLV). Servo.

The rough servo of the spindle motor 9 is
The motor control and command conversion circuit 14 performs based on the FG signal from the spindle driver 11. Further, the motor control and command conversion circuit 14 controls the rotational speed (CLV control) of the magneto-optical disk 2 according to the position of the optical pickup 4 with respect to the magneto-optical disk 2. The CLV control in the motor control and command conversion circuit 14 is performed based on the count value for the feed amount of the stepping motor 10. Furthermore, the motor control and command conversion circuit 14 also performs serial / parallel conversion and various command conversions.

Also, in this optical disk device, the optical pickup 4 and the recording magnetic head 1 are moved to the target track position of the magneto-optical disk 2 designated by the system controller 15.
These movements are performed by the motor control and command conversion circuit 14 based on the designation from the system controller 15.
Is realized by controlling the stepping motor 10 as a drive source of the thread feeding mechanism. In other words, the system controller 15 uses the count value obtained by counting the number of steps of the stepping motor 10 (corresponding to the number of steps corresponding to the thread feed amount, that is, the step address) in the radial direction of the optical pickup 4 on the magneto-optical disk 2. You can know the position. Further, the system controller 15 can know the position of the optical pickup 4 in the radial direction on the magneto-optical disk 2 from the address information corresponding to the wobbling groove read by the optical pickup 4.

The address decoder 7 is used only at the time of writing, for example, and generates an address signal and an FM carrier signal according to a signal corresponding to the wobbling groove on the magneto-optical disk 2 extracted through the RF amplifier 8. , And sends it to the encoder section of the signal processing circuit 6.

At this time, the signal processing circuit 6 sends the address signal to the OWH driver 5, compares the FM carrier signal with a predetermined reference clock signal, and depending on the comparison result, the motor control and command conversion circuit. The spindle motor control unit 14 is controlled.

The system controller 15 is composed of, for example, a CPU (central processing unit), controls each section, and also controls data transmission / reception with a host computer connected to the outside through a terminal 38.

In the optical disk device of the embodiment of the present invention having the above-mentioned structure, the off-track detection by the external impact is realized by the following structure.

That is, in the optical disk device of the embodiment of the present invention, as shown in FIG. 2, the magnitude of the tracking error is within a predetermined first range from the track center (for example, within ± 1/4 track from the track center of the target track). Jo state of whether it is in the range) or a signal ( "H" or "L"
1 as a first off-track signal indicating the state) /
A first off-track signal generating means (1/4 off-track detection circuit shown in FIG. 3 described later) for generating a 4-off-track signal and the magnitude of the tracking error are within a predetermined second range from the track center ( A second off-track signal indicating whether or not it is within ± 1/8 track from the track center of the target track or over ± 3/8 track) by the signal status (“H” or “L” status ) Second off-track signal generating means (1/8 off-track detection circuit shown in FIG. 4 to be described later) for generating the 1/8 off-track signal as the first off-track signal (1 / 4 off-track signal) from state <br/> signal of the second off-track signal (1/8 off-track signal), the generated by an external impact, except for defects and electrical noise of the disk And a shock detection circuit shown in FIG. 7 described later for detecting an off-track of more than one range.

To explain the specific operation, in the optical disk device of this embodiment, the 1/8 off-track signal is "H".
At this time, when the 1/4 off-track signal rises, it is detected that the off-track has occurred due to an external impact. In this case, the shock detection signal from the shock detection circuit described later becomes "H".

The 1/4 off-track detection circuit will be described below in order.

The 1/4 off-track detection circuit is shown in FIG.
It is configured as shown in. The 1/4
The off-track detection circuit is a circuit normally used to generate a traverse signal when a light beam spot crosses a track formed by a groove on a disc.

In FIG. 3, the terminal 46 is connected to the four-division photodiode (each photodiode is usually represented by four of A, B, C, and D) provided in the optical pickup 4 described above. Four signals are provided. The four signals corresponding to A, B, C, and D of the four-division photodiode supplied to the terminal 46 are capacitors C
It is AC-coupled and amplified by the 1 and the inverting amplifier 41 and sent to the comparator 42. The comparator 4
In step 2, the AC-amplified and amplified signal is compared with the level in which the signal has an offset.
These configurations are for detecting that the amount of light is maximized on the track (the center of the groove), and by applying an offset, the off-track signal becomes "L" during normal tracking ON. The output of the comparator 42 is output from the terminal 47 to 1 via the changeover switch 43.
It is output as a / 4 off-track signal.

Here, the changeover switch 43 has the terminal 4
The off-track signal based on the signal from the four-division photodiode and the mirror signal, which will be described later, supplied via the terminal 44 are switched in accordance with the switching control signal supplied from the terminal 5. The mirror signal is used when the signal from the optical disk is a signal from a track consisting of pits, and the signal from the four-division photodiode is obtained from the recording area (that is, groove) of the magneto-optical disk. It is a signal.

The 1/4 off-track signal based on the mirror signal and the signal from the 4-division photodiode is a signal which becomes "L" on the track and "H" between the tracks in any case. The 1/4 off-track signal may have a whisker-like noise due to a defect on the disk, electric noise, or the like.

Next, the 1/8 off-track detection circuit is constructed as shown in FIG. This ⅛ off-track detection circuit detects the ⅛ off-track signal of FIG. 2 based on the tracking error signal.

In FIG. 4, a window comparator composed of open collector comparators 52 and 51 compares a tracking error signal TE supplied through a terminal 50 with a voltage dividing resistance composed of resistors R10, R11 and R12. Take out in comparison with the level. The signal extracted by this window comparator is
The signal is output from the terminal 54 as a 1/8 off-track signal via the low-active inverter 53.

Next, the mirror circuit is constructed as shown in FIG. The mirror circuit is usually a circuit for producing a traverse signal when a light beam spot crosses a track formed by pits on a disc, and is "L" on the track and "at the mirror section between tracks".
The traverse signal of "H" is output as a mirror signal. The mirror circuit outputs a mirror signal of "H" even when a defect on the disk is detected.

In FIG. 5, the RF from the optical pickup 4 as shown in FIG.
Signal is supplied. This RF signal is inverted and amplified by the inverting amplifier 81 via the DC component cutting capacitor C41 to be a signal shown in FIG. 6B, and is sent to the peak hold circuit 82 and the bottom hold circuit 83 in the subsequent stage.

The peak hold circuit 82 is, for example, 30
Capacitor C to follow the traverse of kHz
The capacitance of the capacitor C43 is set, while the bottom hold circuit 83 sets the capacitance of the capacitor C43 so as to set a time constant that can follow the envelope variation of the mirror portion of the disk rotation period. The signal held by the peak hold circuit 82 becomes a peak hold signal H as shown in FIG. 6C, and the signal held by the bottom hold circuit 83 is a bottom hold signal as shown in FIG. 6D. It becomes signal I.

The hold signals H and I are differentiated by the differential amplifier 84, so that the signal J in FIG.
Is made. In the configuration including the voltage dividing resistors of the resistors R44 and R45 in the next stage, the differential amplifier 85, and the diode D41, the level of 2/3 of the peak value of the signal J is peak-held with a large time constant (e) in FIG. Signal K is generated, the signal K is compared with the signal J by the comparator 86, and the output of the comparator 86 is output from the terminal 87 as a mirror signal as shown in (f) of FIG.

Next, the shock detection circuit will be described with reference to FIG.

In FIG. 7, the terminal 65 is supplied with the 1/4 offtrack signal from the 1/4 offtrack detection circuit of FIG. 3 described above, and the terminal 66 is supplied with the 1/8 offtrack signal of FIG.
The 1/8 off-track signal is supplied from the off-track detection circuit, and the terminal 64 is supplied with a shock enable signal for activating the shock detection operation in the shock detection circuit only during signal recording. Further, the terminal 67 is supplied with a shock clear signal for clearing the shock detection operation in the shock detection circuit, and the terminal 68 is supplied with a reset signal for resetting the circuit.

The terminal 65 to which the ¼ off-track signal is supplied is connected to the data input terminal D of the D latch 61, and the terminal 66 to which the ⅛ off-track signal is supplied.
Is connected to the enable terminal E of the D latch 61.

The output terminal Q of the D-latch 61 is connected to the clock input terminal of the D-flip-flop 62. The data input terminal of the D-flip-flop 62 is a terminal 6 to which the shock enable signal is supplied.
It is connected with 4.

Further, a terminal 67 to which the shock clear signal is supplied and a terminal 68 to which the reset signal is supplied.
Is connected to the two input terminals of the NOR gate 63,
The output terminal of the NOR gate 63 is connected to the low active clear terminal of the D-flip-flop 62. The output from the output terminal Q of the D-flip-flop 62 is output via the terminal 69 as an external shock detection output, that is, a shock detection signal.

With respect to the shock detection circuit of FIG. 7 having the above-described structure, when recording a signal, the 1/4 offtrack signal from the 1/4 offtrack detection circuit and the 1/4 offtrack detection circuit from the 1/8 offtrack detection circuit. By supplying the / 8 off-track signal, the shock detection circuit outputs an external shock when the ¼ off-track signal rises when the ⅛ off-track signal is “H” as described above. By ±
It is possible to detect the occurrence of 1/4 track off-track, and it is possible to detect a shock detection signal which becomes “H” at the time of shock detection, that is, ± 1/4 track off-track due to an external shock. In other words, the 1/4 off-track signal may have a whisker-like noise due to a defect on the disk, electric noise, or the like.
According to the above-described configuration of this embodiment, it is possible to accurately detect the ± 1/4 off-tracks due to the external impact in a short time regardless of the influence of defects on the disk, electric noise, and the like.

By the way, even in the optical disc apparatus of the present embodiment capable of writing information on an optical disc such as an MD, as described in the above-mentioned conventional example, for example, an impact from the outside when writing the above-mentioned information. If a signal is added, an off-track may occur in which the beam spot on the optical disc deviates from the target track, and the information already written on another track close to the target track may be destroyed. Therefore, in this embodiment, if the off-track of ± 1/4 track due to the external impact is detected by the configuration of FIGS. 3 to 5 and 7 described above,
With the configuration shown in FIG. 8, the output of the laser diode is immediately switched from recording to reproducing.

Therefore, the optical disk device of this embodiment is
In addition to the configuration shown in FIGS. 3 to 5 and FIG. 7 in the RF amplifier 8, for example, the optical pickup 4 and the PWM driver 12 have a laser drive circuit configured as shown in FIG. That is, in FIG. 8, the optical disk device of the present embodiment also has a transistor Tr1 as a laser output switching means for switching the output of the laser diode LD between recording and reproduction, and the off-track due to the external impact is recorded at the time of recording. If detected, the transistor Tr
When 1 is turned on, the output of the laser diode LD is switched for reproduction. In the configuration of FIG. 8, the CPU 71 and the resistors R21 and R22 are
Is provided in the PWM driver 12 of FIG. 1, for example, and the CPU 71 generates a laser power control signal of the laser diode LD according to the time of recording or reproducing the signal on the disk. The configuration after the APC (auto power control) circuit 73 is built in the optical pickup 4.

In FIG. 8, the APC circuit 73 switches the laser power of the laser diode LD for recording or reproduction by driving the transistor Tr2 based on the laser power control signal represented by the voltage value, and The laser power of the laser diode LD is controlled based on the feedback output of the laser power from the power monitor photodiode PD.

Further, a shock detection signal (off-track detection signal due to external shock) from the shock detection circuit of FIG. 7 is supplied to the terminal 70. The terminal 70 is connected to the base of the transistor Tr1, and the collector of the transistor Tr1 is connected to the laser power control signal input terminal of the APC circuit 73 via the resistor R22. The common connection point of the resistor R22 and the laser power control signal input terminal of the APC circuit 73 is
It is connected to the laser power control signal output terminal of the CPU 71 via the resistor R21. These resistors R22 and R21
When the transistor Tr is turned on by "H" of the off-track detection signal, the voltage value of the laser power control signal, which is the voltage value for recording, can be divided and lowered to the voltage value for reproduction. It is set to a value.

As described above, in the laser drive circuit, a shock detection signal from the shock detection circuit, that is, "H" when an off-track due to an external shock occurs, is supplied from the shock detection circuit through the terminal 70 during signal recording. When,
Since the transistor Tr1 is turned on, the voltage value of the laser power control signal is reduced to the voltage division value by the resistors R22 and R21 (that is, the recording voltage value is reduced to the reproducing voltage value), and based on this, the APC The circuit 73 makes the laser power of the laser diode LD the power for reproduction.

That is, in the laser drive circuit of FIG. 8, when the off-track occurs due to an external impact at the time of recording, the power of the laser diode LD can be immediately switched from the recording power to the reproduction power. In the above, it is possible to prevent the destruction of the information already written in the other tracks close to the target track as described above.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications can be made based on the technical idea of the present invention.

Further, in the above embodiment, an example in which the present invention is applied to an optical disk device for MD data has been described, but a normal optical disk for MD which handles audio data and a normal MD and MD data. It can also be applied to a device for recording / reproducing a disc.

[0069]

As described above, according to the present invention, when the second range is narrower than the first range with respect to the track center, for example, the first off-track signal and the second off-track signal are used. By detecting the off-track using the signal, it is possible to improve the accuracy of detecting the off-track in the first range or more, and the second off-track signal has the tracking error magnitude of the second range or more. The state of the gate means for passing the first off-track signal and the state of the first off-track signal output from the gate means change only when the state indicating Latches a shock enable signal for enabling the off-track detection operation when the value changes from within the first range to above the first range. And an output of the latching means is used as an off-track detection signal due to an external shock, thereby eliminating the influence of a defect on the optical disk other than the external shock or electric noise when the off-track is detected. it can.

Further, in the present invention, if an off-track due to an external shock is detected at the time of recording, the output of the laser oscillator is switched for reproduction, so that even if a track other than the target track is irradiated with the laser beam, It does not destroy the data already recorded.

That is, in the optical disk device of the present invention, the off-track due to the external impact can be detected accurately and in a short time regardless of the influence of the defect on the disk and the electric noise without providing the guard band.
Further, it is possible to prevent the information recorded on another track close to the target track from being destroyed.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a schematic configuration of an optical disk device of an embodiment of the present invention.

FIG. 2 is a waveform diagram showing a relationship between a tracking error signal, a 1/4 off-track signal, and a 1/8 off-track signal in the apparatus of this embodiment.

FIG. 3 is a circuit diagram showing a specific configuration of a 1/4 off-track detection circuit.

FIG. 4 is a circuit diagram showing a specific configuration of a 1/8 off-track detection circuit.

FIG. 5 is a circuit diagram showing a specific configuration of a mirror circuit.

FIG. 6 is a waveform diagram showing waveforms at various parts of the mirror circuit.

FIG. 7 is a circuit diagram showing a specific configuration of a shock detection circuit.

FIG. 8 is a circuit diagram showing a specific configuration of a laser drive circuit.

FIG. 9 is a diagram showing a disc type of an MD and a recording layout.

FIG. 10 is a diagram showing an outline of a recordable disc format.

[Explanation of symbols]

1 Recording magnetic head 2 magneto-optical disk 4 Optical pickup 5 OWH driver 6 Signal processing circuit 7 Address decoder 8 RF amplifier 9 Spindle motor 10 Stepping motor 11 Spindle driver 13 Servo circuit 14 Motor control circuit 15 System controller 16 ROM

─────────────────────────────────────────────────── --- Continued from the front page (56) References JP-A-6-111349 (JP, A) JP-A-4-147437 (JP, A) JP-A-6-89452 (JP, A) JP-A-6- 12695 (JP, A) JP 8-45079 (JP, A) JP 7-201042 (JP, A) JP 7-29187 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B ^7/ 08-7/10

Claims (2)

(57) [Claims] 1. A first off-track for generating a first off-track signal from a light amount detection signal, which indicates by a signal state whether or not the magnitude of the tracking error is within a predetermined first range from the track center. A signal generating means, and a second off-track signal indicating from the tracking error signal whether or not the magnitude of the tracking error is within a second range narrower than the first range from the track center. the second and the off-track signal generating means, said second off-track signal, only when the magnitude of the tracking error is a state indicating that at least said second range, said first off-track Pass the signal
A gate means for, in the state of the first off-track signal output from the gate means is changed, when the magnitude of the tracking error is changed over the first range within the first range To enable off-track detection operation
Means for latching a shock enable signal for
With the door, the output of the latch means, Luo off track by the external impact
An optical disk device, which is used as a detection signal of a. 2. A laser output switching means for switching the output of the laser oscillator between at least for recording and for reproducing is provided, and if an off-track due to the external impact is detected during recording, the laser output switching means is the laser oscillator. 2. The optical disc device according to claim 1, wherein the output of the optical disc is switched for reproduction.