JP2006209820A - Optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk device capable of making an optical pickup shift smoothly to a next zone, without increasing the seek time, even when the optical pickup erroneously lands on a zone boundary. <P>SOLUTION: An optical disk device 60 is equipped with a header detection signal generating part 78, 100 which generates a header detection signal which shows a header area, based on the signal difference of a first beam spot and a second beam spot obtained by bisecting a light beam; a zone boundary determining part 101, which determines the boundary area of zones by the change of the pattern of the header detection signal; and a tracking control circuit 88, which, when an optical spot lands on the boundary area of zones when seeking which moves the the optical spot to recording sectors becoming an object of recording/reproduction, makes the optical spot jump to tracks other than the boundary area of the zones. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical disc apparatus.

  The DVD-RAM has a recording area divided into zones including a plurality of tracks. In the DVD-RAM, both lands and grooves adjacent to each other are used as recording / reproducing areas in order to increase the recording capacity.

  Each track is composed of a plurality of sectors, and a PID (Physical ID) is recorded in the header area of each sector by a CAPA (Complimentary Allocated Pit Addressing) method. PID is address information used for reproduction and recording. The header area storing the PID is arranged as a pair of staggered pit rows between the land track and the groove track.

  The first half of the pair of header areas stores the land track address, and the second half stores the groove track address. Further, the address of the first half part and the address of the second half part of the header area have an address difference of one track, and the smaller address value becomes the address information of the track being accessed.

  In the DVD-RAM format, the first track of each zone is a groove, and the last track is a land. Further, the number of sectors per disk circumference varies from zone to zone, and the number of sectors per disk circumference increases by one as the number of zones increases from the inner circumference toward the outer circumference. Accordingly, at the boundary between adjacent zones (hereinafter referred to as zone boundary), there is a deviation in the arrangement of the first half of the header area and the latter half of the last land track (first last track) of the zone. As a result, the zigzag shape of the header region is broken, and the first half and the second half thereof are arranged at illegal intervals (see FIG. 4). Accordingly, the generation of the tracking error signal (TE signal) becomes irregular, and the generation interval of the header detection signal generated based on the TE signal becomes illegal. As a result, since the flywheel cannot be locked, there arises a problem that the generation interval of the header gate signal is not guaranteed.

  In order to cope with this problem, there has been proposed a technique of jumping to the next zone while avoiding a land track that is a zone boundary when the pickup is in the last groove track of the zone (Patent Document 1). In this technique, switching between land / groove polarity signals (hereinafter referred to as LG polarity signals) is executed based on PID data.

  However, the zone boundary track does not record user information as a guard area. Therefore, although the target track at the time of seek is not set, if the pickup accidentally lands on the zone boundary, the header signal generation interval is not guaranteed as described above, and it becomes difficult to detect the PID.

Further, there is a technique for determining land / groove polarity based on a TE signal (Patent Document 2). However, since the TE waveform at the zone boundary is difficult to predict the header, the servo hold is not performed at the correct position, and the CAPA appears only on one side due to the deviation of the header area. Can't get. Thereby, it may be difficult to determine the switching between the land and the groove. As a result, if the pickup accidentally lands on the zone boundary during seek, the land track at the zone boundary cannot move to the first groove track of the next zone, and may remain in the same land track. . This operation may continue forever like an infinite loop without reading the PID. In such a case, the CPU needs to end this operation with a timer. As a result, there is a problem that the seek time is increased.
Japanese Patent Laid-Open No. 11-110663 Japanese Patent Laid-Open No. 10-11760

  Provided is an optical disc apparatus capable of smoothly moving a pickup to the next zone without increasing a seek time even when the pickup has accidentally landed on a zone boundary.

  An optical disk device according to an embodiment of the present invention is an optical disk device that records or reproduces information by irradiating an optical disk medium with a light beam, and includes a first beam spot obtained by dividing the light beam into a plurality of parts. A header detection signal generation unit configured to generate a header detection signal indicating a header region based on a difference signal or a sum signal with respect to the second beam spot; and a plurality of groove tracks based on a change in the header detection signal. And a zone boundary determination unit that determines that the zone is a boundary region between zones composed of a plurality of land tracks, and the light beam is moved when the light beam is moved with a certain recording sector as a target. A tracking control circuit for jumping the light beam to a track other than the boundary region of the zone It is provided with.

  The optical disc apparatus according to the present invention can smoothly move the pickup to the next zone without increasing the seek time even when the pickup accidentally lands on the zone boundary.

  Embodiments according to the present invention will be described below with reference to the drawings. This embodiment does not limit the present invention. In the following embodiment, the zone boundary of the DVD-RAM is determined by the change in the pattern of the header detection signal. As a result, it is possible to reliably detect that the pickup is at the zone boundary in a short time and to prevent an increase in seek time.

(First embodiment)
FIG. 1 is a configuration diagram of the DVD-RAM 1. In general, the DVD-RAM 1 employs a ZCLV (Zoned Constant Linear Velocity) method. The DVD-RAM 1 is divided into a plurality of zones 43a to 43x. Each of the zones 43a to 43x includes a plurality of tracks (not shown). The track is a recording area formed on the disk in a circular shape and corresponding to one round of the disk. The track includes a groove track and a land track, and the groove track and the land track are alternately formed on the disc. At the switching point between the groove track and the land track, the pickup shifts from the groove track to the land track or from the land track to the groove track. As a result, the pickup continuously and alternately scans the groove track and the land track every round of the disk. In each zone, the first track is a groove and the last track is a land. In the DVD-RAM 1, both the groove track and the land track are recording areas. The track is divided into a plurality of recording sectors, and user data is recorded in the recording sectors. The number of sectors per track for each zone is the same, and the number of sectors per track sequentially increases by one each time the zone shifts from the inner zone to the outer zone.

  2 and 3 are diagrams showing a configuration in the vicinity of the header area between adjacent recording sectors. FIG. 2 shows the header area at the groove / land switching point. FIG. 3 shows a header area in the middle of the groove track or land track.

  A header area HDR0 is provided at the head of each recording sector. The header area HDR0 includes a first header part HDR1 and a second header part HDR2. The first header portion HDR1 is shifted from the land track by a half pitch in the inner radial direction of the disc, and is provided corresponding to the recording sector in the land track. The second header portion HDR2 is shifted by a half pitch in the direction opposite to that of the first header portion HDR1, and is provided corresponding to the recording sector in the groove track. As described above, between the adjacent recording sectors, the first header portion HDR1 and the second header portion HDR2 are adjacent to each other in the circumferential direction of the disc while being shifted by one pitch in the radial direction of the disc. That is, the first header portion HDR1 and the second header portion HDR2 are arranged in a staggered manner as shown in FIGS.

  In the header area HDR0, address information of the corresponding recording sector is recorded. Further, the land / groove polarity can be determined from the size relationship of the address information stored in the first header portion HDR1 and the second header portion HDR2. Therefore, it is important to detect the header area HDR0 when recording / reproducing data.

  FIG. 4 is a diagram schematically showing the reproduction waveform of the recording sector and the header area in the boundary area between adjacent zones when the disk rotation speed is constant. When the number of revolutions of the disk is constant, the generation interval of each recording sector S is the same in the same zone and is different between the zones. Further, due to the physical arrangement with respect to the disk, the arrangement of headers that are normally arranged in a staggered manner at the zone boundary portion is destroyed. In FIG. 4, G indicates a groove sector, and L indicates a land sector.

  FIG. 5 is a configuration diagram of the optical disc device 60 according to the embodiment of the present invention. The optical disk device 60 is a device that records data using focused light on an optical disk (DVD-RAM) 40 as a recording medium, and reproduces the data recorded on the optical disk 40. The optical disk device 60 includes an optical disk control device 62 that instructs recording or reproduction.

  The optical disc 40 is rotated by the motor 63 at, for example, a different rotational speed for each zone. The motor 63 is controlled by a motor control circuit 64.

  Data recording or reproduction is performed by the optical head 65. The optical head 65 is fixed to a drive coil 67 that constitutes a movable part of the linear motor 66, and the drive coil 67 is connected to a linear motor control circuit 68.

  A speed detector 69 is connected to the linear motor control circuit 68 and sends a speed signal of the optical head 65 to the linear motor control circuit 68. Further, a permanent magnet (not shown) is provided in the fixed portion of the linear motor 66, and the optical head 65 is moved in the radial direction of the optical disk 40 by exciting the drive coil 67 by the linear motor control circuit 68. The

  An objective lens 70 is supported on the optical head 65 by a wire or a leaf spring (not shown). The objective lens 70 is moved in the focusing direction (the optical axis direction of the lens) by the drive coil 71 and is tracked by the drive coil 72. It is movable in a direction (perpendicular to the optical axis of the lens).

  Further, when the semiconductor laser oscillator 79 is driven by the laser control circuit 73, laser light is generated. The laser control circuit 73 corrects the amount of laser light from the semiconductor laser oscillator 79 in accordance with the monitor current from the monitoring photodiode PD of the semiconductor laser oscillator 79.

  The laser control circuit 73 operates in synchronization with a recording clock signal from a PLL circuit (not shown). The PLL circuit divides a basic clock signal from an oscillator (not shown) to generate a recording clock signal.

  Laser light generated from the semiconductor laser oscillator 79 driven by the laser control circuit 73 is irradiated onto the optical disc 40 through the collimator lens 80, the half prism 81, and the objective lens 70. The reflected light from the optical disc 40 is guided to the photodetector 84 through the objective lens 70, the half prism 81, the condenser lens 82, and the cylindrical lens 83.

  The light detector 84 is constituted by four divided light detection cells 84a, 84b, 84c, and 84d. The output signal of the light detection cell 84a of the light detector 84 is supplied to one end of the adder 86a via the amplifier 85a, and the output signal of the light detection cell 84b is supplied to one end of the adder 86b via the amplifier 85b. The output signal of the photodetection cell 84c is supplied to the other end of the adder 86a via the amplifier 85c, and the output signal of the photodetection cell 84d is supplied to the other end of the adder 86b via the amplifier 85d.

  The output signal of the light detection cell 84a is supplied to one end of the adder 86c via the amplifier 85a, and the output signal of the light detection cell 84b is supplied to one end of the adder 86d via the amplifier 85b, and the light detection cell 84c. Is supplied to the other end of the adder 86d via the amplifier 85c, and the output signal of the light detection cell 84d is supplied to the other end of the adder 86c via the amplifier 85d.

  The output signal of the adder 86a is supplied to the inverting input terminal of the differential amplifier OP2, and the output signal of the adder 86b is supplied to the non-inverting input terminal of the differential amplifier OP2. Thereby, the differential amplifier OP2 supplies a signal (focus error signal) relating to the focus point to the focusing control circuit 87 in accordance with the difference between the adders 86a and 86b. The output signal of the focusing control circuit 87 is supplied to the focusing drive coil 71. The focusing drive coil 71 is controlled so that the laser light is always kept in focus on the optical disc 40.

  The output signal of the adder 86c is supplied to the inverting input terminal of the differential amplifier OP1, and the output signal of the adder 86d is supplied to the non-inverting input terminal of the differential amplifier OP1. Thereby, the differential amplifier OP1 supplies a tracking error signal to the tracking control circuit 88 and the data reproduction circuit 78 in accordance with the difference between the adders 86c and 86d. The tracking control circuit 88 creates a track drive signal according to the tracking error signal supplied from the differential amplifier OP1.

  The track drive signal output from the tracking control circuit 88 is supplied to the drive coil 72 in the tracking direction. The tracking error signal used in the tracking control circuit 88 is supplied to the linear motor control circuit 68.

  When the objective lens 70 is moved by the tracking control circuit 88, the linear motor control circuit 68 moves the linear motor 66, that is, the optical head 65 so that the objective lens 70 is positioned in the vicinity of the center position in the optical head 65. Let

  The sum signal of the outputs of the light detection cells 84a to 84d of the light detector 84 in the state where focusing and tracking are performed as described above, that is, a signal obtained by adding the output signals from the adders 86c and 86d by the adder 86e. Reflects the change in reflectance from the pits (recording data) formed on the track. This signal is supplied to the data reproduction circuit 78, and the data reproduction circuit 78 reproduces the recorded data.

  The zone boundary determination circuit 101 is connected to the output of the adder 86e and the output of the differential amplifier OP1. Further, the zone boundary determination circuit 101 is connected so as to receive a header detection signal from the data reproduction circuit 78 and the header protection circuit 100. Further, the output of the zone boundary determination circuit 101 is connected to the tracking control circuit 88, and a determination result indicating whether or not the pickup has landed on the zone boundary can be output to the tracking control circuit 88.

  Hereinafter, basic operations of the optical disc apparatus will be described.

[Recording operation to DVD-RAM]
A data generation circuit 74 is provided in front of the laser control circuit 73. The data generation circuit 74 includes an ECC block data generation circuit 74a and a modulation circuit 74b. The ECC block data generation circuit 74a converts the format data of the ECC block as the recording data supplied from the error correction circuit 92 into the format data of the ECC block for recording to which the synchronization code for the ECC block is added. The modulation circuit 74b modulates the recording data from the ECC block data generation circuit 74a by the 8-16 code conversion method.

  The data generation circuit 74 is supplied with the record data to which the error correction code is given by the error correction circuit 92 and the error check dummy data read from the memory 10. The error correction circuit 92 is supplied with recording data from the optical disk control device 62 via the interface circuit 95 and the bus 89.

  The error correction circuit 92 assigns the error correction codes (ECC1, ECC2) in the horizontal direction and the vertical direction to the recording data in units of sectors for every 2 Kbytes to the recording data of 32 Kbytes supplied from the optical disc control device 62. . At the same time, the error correction circuit 92 assigns a sector ID (logical address number) and generates format data of the ECC block.

  The optical disc device 61 includes a focusing control circuit 87, a tracking control circuit 88, and a D / A converter 91. The D / A converter 91 is used for transmitting and receiving information between the linear motor control circuit 68 and the CPU 90 that controls the entire optical disk apparatus.

  The motor control circuit 64, linear motor control circuit 68, laser control circuit 73, data reproduction circuit 78, focusing control circuit 87, tracking control circuit 88, error correction circuit 93 and the like are controlled by the CPU 90 via the bus 89. The CPU 90 executes a predetermined operation according to the control program recorded in the memory 93.

  The memory 93 stores a control program and is used for data recording. In the memory 93, the number of rotations (speed data) for each zone 43a,... 43x in FIG.

  FIG. 6 is a circuit diagram showing a configuration of the tracking control circuit 88. The tracking control circuit 88 includes a changeover switch 101, a polarity inversion circuit 102, a phase compensation circuit 103, and a drive circuit 104.

  The changeover switch 101 is switched based on a tracking polarity switching signal (land / groove switching signal) from the CPU 90. When the polarity of the tracking polarity switching signal is groove, the changeover switch 101 outputs the track error signal from the differential amplifier OP1 to the phase compensation circuit 103. When the polarity of the tracking polarity switching signal is land, the changeover switch 101 outputs a track error signal whose polarity has been inverted by the polarity inversion circuit 102 to the phase compensation circuit 103. The CPU 90 determines from the read address (PID) information whether the track being accessed is a land or a groove. The CPU 90 further outputs a tracking polarity switching signal. This switching process occurs every round.

  The polarity inversion circuit 103 inverts (in reverse phase) the polarity of the track error signal supplied from the differential amplifier OP1. The output of the polarity inversion circuit 103 is supplied to the changeover switch 102.

  The phase compensation circuit 103 compensates the phase of the positive polarity (normal phase) track error signal or the reverse polarity (reverse phase) track error signal supplied from the changeover switch 101, and outputs it to the drive circuit 104.

  The drive circuit 104 moves the objective lens 70 in the tracking direction by driving the drive coil 71 with the track drive signal from the phase compensation circuit 103.

[Mechanism of optical disc device 61]
The optical head 65 mounted on the optical disk device 61 of FIG. 1 has a home position, and is controlled so that the optical head 65 is always located at this position when the power is turned on. The home position is mechanically designed so that the radial position becomes a predetermined value. The CPU 90 knows what zone the home position is, and determines the rotational speed of the optical disc 40 in accordance with this zone. Reads the sector address of the current position at the home position.

  When it is desired to seek a certain sector at the time of data recording / reproduction, the CPU 90 calculates the distance between the address of the seek destination sector and the address of the current position, and a linear motor 67 as a coarse movement mechanism of the optical head 65. Drive. Since the zone number and the rotational speed can be known from the address of the sector to which the data is sought, the motor 63 rotates the optical disc 40 at the rotational speed.

  Thereafter, when the optical head 65 moves, the moving position is confirmed by reading the header area. The CPU 90 calculates the difference between the moved position and the target sector of the seek destination, and uses the tracking control circuit 88 to jump to the target sector. Actually, the optical head 65 moves with a track about one or two laps before the seek destination address as a target. The CPU 90 calculates in advance whether the target sector is a land or a groove.

[Recording operation across zone boundaries]
For example, it is assumed that recording (writing) is performed from a predetermined ECC block (zone 0). At this time, a data recording instruction and data to be recorded are supplied from the optical disc control device 62 into the optical disc device 61 via the interface circuit 95. Thereby, the data recording instruction is supplied to the CPU 90, and the recording data is stored in the memory 93.

  As a result, the CPU 90 determines recording from the head sector of the ECC block. The CPU 90 determines the rotation speed corresponding to the zone 0 including the head sector, together with the address including the track number and the sector number corresponding to the head sector.

  In response to this determination, the CPU 90 rotates the optical disc 40 at a rotational speed corresponding to the zone 0, and moves the irradiation position of the laser light from the optical head 65 to a position corresponding to the address. This is called access processing.

  After this access processing is performed, the CPU 90 newly assigns a correction code to generate recording data of the first ECC block, and records this on the optical disc 1.

  Thereafter, data is recorded in ECC blocks supplied from the optical disc control circuit 62 and continuous in the same zone. After recording the data in the last ECC block of zone 0, the CPU 90 determines the shift to zone 1 and changes the rotation of the optical disc 40 to the rotation speed corresponding to zone 1.

  As a result, data is recorded sequentially from the first ECC block in the user area of zone 1. When data is recorded across the zone boundary, a constant transfer rate can be ensured over the entire surface of the optical disk due to the relationship between the rotational speed of the optical disk 40 and the number of sectors per track as described above.

[Playback operation across zone boundaries]
For example, assume that reproduction (reading) is performed from a predetermined ECC block (zone 0). At this time, a data reproduction (read) instruction is supplied from the optical disc control device 62 to the CPU 90 in the optical disc device 61 via the interface circuit 95. Thereby, the CPU 90 determines the reproduction from the head sector of the predetermined ECC block. The CPU 90 determines the rotation speed corresponding to the zone 0 including the head sector, together with the address including the track number and the sector number corresponding to the head sector. In response to this determination, the CPU 90 performs access processing.

  After the access processing is performed, the CPU 90 outputs data in units of ECC blocks demodulated by the demodulation circuit 208 (see FIG. 8) in the data reproduction circuit 78 to the error correction circuit 92 for each sector area. As a result, data for one ECC block is supplied to the error correction circuit 92, and error correction processing is performed using ECC1 and ECC2.

  When the error correction process ends normally, the CPU 90 outputs the reproduction data of the ECC block to the optical disc control circuit 62 through the interface circuit 95 as a reproduction result.

  Thereafter, the reproduction data of consecutive ECC blocks in the same zone is output to the optical disc control circuit 62. After the reproduction data of the last ECC block in the user area of zone 0 is output to the optical disc control circuit 62, the CPU 90 determines the transition to zone 1 and rotates the optical disc 40 at the rotational speed corresponding to zone 1.

  As a result, the reproduction data is output to the optical disc control circuit 62 in order from the data of the first ECC block in the user area of zone 1. When reproducing over zone boundaries, the transfer rate can be stabilized by the relationship between the rotational speed of the optical disc 40 and the number of sectors per track.

  Hereinafter, the configurations and operations of the data reproduction circuit 78, the header protection circuit 100, and the zone boundary determination circuit will be described in more detail. The data reproduction circuit 78 and the header protection circuit 100 function as a header detection signal generation unit.

[Generation of reproduction signal by data reproduction circuit 78]
7 and 8 are configuration diagrams of the data reproduction circuit 78. FIG. The data recovery circuit 78 includes a switch SW1, a full-wave rectifier 201, binarization circuits 202 and 204, a switch SW2, a low-pass filter (LPF) 203, a sync detection circuit 205, an AM detection circuit 206, A PLL circuit 207 and a demodulation circuit 208 are provided.

  The data reproduction circuit 78 receives the push-pull signal and the sum signal of the reproduction RF waveform. The push-pull signal is an output signal from the differential amplifier OP1. The sum signal is an output signal from the adder 86e.

  The switching element SW1 selects either the push-pull signal or the sum signal by the gate signal HEADGT. The full wave rectifier 201 converts the negative polarity signal of the push-pull signal into a positive polarity signal. The binarization circuit 202 converts the push-pull signal or the sum signal into binary data (reproduced binary signal).

  The reproduced binary signal is input to the sync detection circuit 205, the AM detection circuit 206, and the PLL circuit 207 shown in FIG. The PLL circuit 207 generates a channel clock from the binarized signal, and supplies the channel clock to the sync detection circuit 205, the AM detection circuit 206, and the demodulation circuit 208. The sync detection circuit 205 detects a desired sync pattern sequence recorded in the user area from the reproduced binary signal, and generates data demodulation timing of the user area, that is, serial-parallel conversion timing. Similarly, the AM detection circuit 206 detects a desired AM pattern string formed in advance in the header area from the reproduced binary signal, and generates data demodulation timing in the header area. The header area address information (PID information) and the like are obtained based on the demodulation timing obtained by the sync detection circuit 205 and the AM detection circuit 206.

  FIG. 9 is a waveform diagram of a reproduction signal processed by the data reproduction circuit 78. In this figure, signal waveforms corresponding to two recording sectors S (hereinafter also referred to as user area S) and two header areas HDR0 are shown.

  The push-pull signal is a signal indicating a signal difference between a first beam spot and a second beam spot obtained by dividing a light beam used as a pickup into a plurality of parts. For example, the light beam may be divided into two, with one beam as the first beam spot and the other beam as the second beam spot. The light beam may be divided into four A, B, C, and D, the first beam spot may be (A + D), and the second beam spot may be (B + C). The light beam may be further divided into 2 m or more (m is an integer of 3 or more). In this case, m beams out of the light beams are used as first beam spots, and the other m beams are used as second beam spots.

  In the push-pull signal, no waveform appears in the user area S, and an RF waveform appears only in the header area HDR0. Therefore, the push-pull signal is suitable for reproducing information in the header area HDR0. The push-pull signal in the header part has different polarities between the first header part HDR1 and the second header part HDR2 by the CAPA method. The first header part HDR1 has a negative polarity. A full wave rectification circuit 201 performs full wave rectification on the push-pull signal. When the gate signal HEADGT becomes high in the header region HDR0, the switch SW1 in FIG. 7 is connected to the push-pull side (N1). Thereby, the RF signal of the header area HDR0 is extracted.

  On the other hand, the RF signal of the user area S is extracted from the sum signal. The sum signal is the sum of the signal from the first beam spot and the signal from the second beam spot obtained by dividing the light beam into two. In the sum signal, an RF waveform appears in the user area S and the header area HDR0. When the gate signal HEADGT goes low in the user area S, the switch SW1 in FIG. 7 is connected to the sum signal side (N2). Thereby, the RF signal of the user area S is extracted.

  The selection signal input to the binarization circuit 202 in FIG. 7 is a reproduction signal obtained by combining the RF signals in the header area HDR0 and the user area S as shown in FIG. This RF signal is binarized by the binarization circuit 202 and further demodulated by the demodulation circuit 208 shown in FIG. Thereby, demodulated data and PID information are obtained.

  In general, playback is performed using a push-pull signal and a sum signal in a 2.6 GB disc, and both signals in the header area and user area are extracted from the sum signal in a 4.7 GB disc. The

[Generation of Header Detection Signal by Data Recovery Circuit 78]
As shown in FIG. 7, the sum signal and the push-pull signal after full-wave rectification are connected to the switch SW2. The sum signal input to the switch SW2 and the push-pull signal after full-wave rectification are used to generate a header detection signal. At this time, when recording / reproducing data using a 2.6 GB disc, the switch SW2 is connected to the push-pull side (N1). When recording / reproducing data using a 4.7 GB disk, the switch SW2 is connected to the sum signal side (N2). The switch SW2 is switched by the control CPU of the optical disc control device 62.

  FIG. 10 is a waveform diagram of various signals in the case of a 2.6 GB disk, that is, when a header detection signal is generated using a push-pull signal. The RF signal, push-pull signal, and push-pull signal after full-wave rectification are the same as those shown in FIG. The LPF 203 cuts a high-frequency component of the push-pull signal after full-wave rectification. Thereafter, the binarization circuit 204 binarizes the push-pull signal. Thereby, a binarized header detection signal is generated. Thus, the header detection signal obtained using the RF signal is referred to as a header detection signal (byRF).

  FIG. 11 is a waveform diagram of various signals in the case of a 4.7 GB disk, that is, when a header detection signal is generated using a sum signal. The RF signal and the sum signal are the same as those shown in FIG. The LPF 203 cuts high frequency components of the sum signal. Thereafter, the binarization circuit 204 binarizes the sum signal. Thereby, a header detection signal (byRF) is generated.

  Usually, since only one of 2.6 GB disk and 4.7 GB disk is used, the header detection signal (byRF) of the 2.6 GB disk and the header detection signal (byRF) of the 4.7 GB disk are not particularly distinguished here.

[Generation of Header Detection Signal by Header Protection Circuit 100]
12 and 13 are block diagrams showing the configuration of the header protection circuit 100. FIG. FIG. 14 is a waveform diagram of signals processed by the header protection circuit 100. Normally, the TE signal is stable in the user area S as shown in FIG. 14 due to the influence of the tracking servo. However, in the header area HDR0, there is a large fluctuation due to the influence of the first header part HDR1 and the second header part HDR2 arranged in a staggered manner. Usually, in the header area HDR0, the tracking servo is held or the tracking servo gain is reduced.

  The TE signal is a signal indicating how much the pickup is deviated from the center position of the track. The TE signal is zero when the pickup is located at the center of the track, and increases as an absolute value in the positive or negative direction as the distance from the center increases.

  In the header protection circuit 100 shown in FIG. 12, the LPF 301 first cuts the high frequency component of the TE signal. Thereafter, the TE signal is input to each of the comparators 302 and 303. The comparator 302 compares the TE signal with the upper potential A and cuts a signal portion higher than the upper potential A. The comparator 303 compares the TE signal with the lower potential B and cuts a signal portion lower than the lower potential B. Thereby, as shown in FIG. 14, an upper slice signal and a lower slice signal are obtained.

  The output of the comparator 302 and the inverted output of the comparator 303 are connected to the OR circuit 304. The OR circuit 304 performs an OR operation on the inverted signal of the lower slice signal and the upper slice signal. As a result, as shown in FIG. 14, a signal obtained by ORing the inverted signal of the lower slice signal and the upper slice signal is obtained.

  The output of the OR circuit 304 is connected to the single signal generation circuit 305. The unification signal generation circuit 305 unifies the signal after the OR operation for each header area HDR0. More specifically, the single signal generation circuit 305 masks the second rise of the signal after the OR operation. This makes it possible to generate a pulse that continues from the first rising edge of the signal after the OR operation to the end point of the header area HDR0 (period T1). The unification is to generate a pulse that continues in one shot from the first rising edge of the signal after the OR operation to the end point of the header area HDR0. This unified signal becomes a header detection signal. Thus, the header detection signal obtained from the TE signal is referred to as a header detection signal (byTE).

  The header detection signal (byTE) is input to the header protection counter 308 and the period measurement counter 309 shown in FIG. The period measurement counter 309 measures the generation interval of the header detection signal (byTE). The header protection counter 308 is controlled based on the generation interval of the header detection signal (byTE). Under the control of the header protection counter 308, the flywheel is executed for the header detection signal. The flywheel suppresses the TE signal from becoming unstable due to fluctuations in the disc playback rate and the effects of disc scratches. Thereby, the distinction between the header area and the user area becomes more stable.

  Note that the rising position and the pulse width of the pulse of the header detection signal (byRF) are approximated to the start point and the width of the header region HDR0 compared to those of the header detection signal (byTE).

  The PID data reproduced by the data reproduction circuit 78 shown in FIG. 1 is output to the CPU 90 shown in FIG. 1, and the control MPU grasps the pick position from the PID data. The user data reproduced by the data reproduction circuit 78 is error-corrected by the error correction circuit 92 using the assigned error correction code ECC, and then transmitted to the optical disk control device 62 as an external device via the interface circuit 95. Is output.

[Generation of Track Jump Signal by Zone Boundary Determination Circuit 101]
FIG. 15 is a block diagram showing a configuration of the zone boundary determination circuit 101. The zone boundary determination circuit 101 includes a switch SW3, a period measurement circuit 401, a width measurement circuit 402, and a zone boundary determination unit 403. The switch SW3 is configured to be able to select either the header detection signal (byTE) or the header detection signal (byRF). The header detection signal (byTE) can be obtained from the header protection circuit 100 shown in FIG. The header detection signal (byRF) can be obtained from the data reproduction circuit 78 shown in FIG.

  Whether to select the header detection signal (byRF) or the header detection signal (byTE) is systematically determined by the detection accuracy of each header detection signal at the zone boundary. Practically, it is preferable to select a header detection signal (byRF) that is not easily affected by tracking and has good header width reproducibility. Hereinafter, the header detection signal (byRF) or the header detection signal (byTE) selected by the switch SW3 is simply referred to as a header detection signal.

  The header detection signal selected by the switch SW3 is input to the period measurement circuit 401 and the width measurement circuit 402. The period measurement circuit 401 measures the interval of the occurrence time of the rise of the header detection signal. The width measurement circuit 402 measures the pulse width of the header detection signal.

  Thereafter, the header detection signal is input to the zone boundary determination unit 403. In the zone boundary determination unit 403, zone boundary conditions are set in advance by the CPU. When the header detection signal satisfies the zone boundary condition, the zone boundary determination unit 403 determines that the pickup has landed on the zone boundary.

  The zone boundary determination unit 403 outputs the determination result to the tracking control circuit 88 as a track jump signal. Thereby, the track jump is executed in the forward direction or the reverse direction (method A). Alternatively, the zone boundary determination unit 403 may output a track jump signal to the CPU 90, and the CPU 90 that has received the track jump signal as an interrupt signal may output the track jump signal to the tracking control circuit 88 (method B).

  The jump direction (forward direction or reverse direction) is determined in advance depending on whether the search target track is a track in the next zone with respect to the zone boundary or a track in front of the guard area in the same zone. In the case of the method A, it is necessary to set the direction to jump to the CPU 90 in advance. In the case of method B, the jump direction may be determined after the CPU 90 receives the interrupt signal. This allows track jumping when the pickup is at the zone boundary.

  FIG. 16 is a timing diagram showing a zone boundary determination method according to the first embodiment of the present invention. In FIG. 16, the zone boundary determination operation is shown, and the track jump according to the determination result is not shown.

  The upper side of FIG. 16 shows a recording sector (user area) S and header portions HDR1 and HDR2 at the zone boundary as in FIG. L indicates a land sector, and G indicates a groove sector. The pickup scans the land track in the direction of arrow A. The land track circulates on the disk and is connected to the land track indicated by the arrow A '. The pickup scans the land track in the direction of arrow A 'and reaches the land / groove switching point. At this time, the pickup moves from the land to the groove. Thereafter, the pickup scans the groove track in the direction of arrow B. This groove track goes around the disk and is connected to the groove track indicated by arrow B '. This pickup is repeated, and the pickup is performed by the groove track indicated by arrow B ′, the land track indicated by arrow C, the land track indicated by arrow C ′, the groove track indicated by arrow D, the groove track indicated by arrow D ′, and the land indicated by arrow E. Move to the track. That is, the pickup moves from the inner side to the outer side of the disc while repeatedly scanning the land track and the groove track.

  Note that the zone boundary is a land track indicated by arrows C and C '. In tracks other than the land tracks indicated by arrows C and C ', the first header portion HDR1 and the second header portion HDR2 are adjacent to each other in the circumferential direction while being shifted by one pitch in the radial direction of the disc. On the other hand, in the land tracks indicated by arrows C and C ', the first header portion HDR1 and the second header portion HDR2 are in a state shifted by one pitch in the radial direction of the disc, but are separated in the circumferential direction.

  FIG. 16 is a conceptual diagram showing a header detection signal when the pickup scans the tracks indicated by arrows B ′ and C ′, and a zone boundary determination method using the header detection signal.

  Tracks indicated by arrows A, A ', B, and B' before the zone boundary are set as zone Z, and tracks indicated by arrows D, D ', and E after the zone boundary are set as zone Z + 1. In the zone Z, the sector length is detected by X ± α including an error of ± α in the actual sector length X. In the zone Z + 1, the sector length is detected as Y ± α including an error of ± α in the actual sector length Y. Since the zone Z + 1 is located on the outer periphery of the zone Z, the relationship X> Y is established.

  Referring to the header detection signal, since the first header portion HDR1 and the second header portion HDR2 are adjacent to each other in the track indicated by the arrow B ', normal pulses P1 to P3 are generated. The rising interval of the pulses P1 to P4 (hereinafter referred to as pulse generation interval) is X ± α. However, in the track indicated by the arrow C ′ that is the zone boundary, the first header portion HDR1 and the second header portion HDR2 are separated from each other, so that abnormal (illegal) pulses P5 to P18 are generated. The pulse generation interval of the pulses P5 to P18 is narrower than X ± α. In this way, the waveform pattern of the header detection signal changes at the zone boundary.

  Note that the pulse generation intervals of the pulses P1 to P18 are measured by the period measurement circuit 401 in FIG. The period measuring circuit 401 measures the pulse generation interval with a high-speed clock or the like. The high-speed clock is preferably a fixed clock such as crystal precision, and it is better to avoid a clock whose rate varies such as a channel clock or a wobble signal.

  The zone boundary determination unit 403 in FIG. 15 stores a threshold value, and activates “zone boundary determination signal 1” when the pulse generation interval falls below this threshold value. The threshold is a value sufficiently smaller than X-α, and is, for example, (X-α) / 2.

  The zone boundary determination circuit 101 determines that the pickup is at the zone boundary when the pulse generation interval falls below the threshold value and this continues for n times (n is a natural number). The zone boundary determination circuit 101 outputs a track jump pulse based on this determination result.

  More specifically, when the pickup enters the zone boundary, an interval ("-" or "*") shorter than X-α occurs. “-” In FIG. 16 represents a case where the pulse generation interval is shorter than X-α but is equal to or greater than the threshold value. At this time, no pulse is generated in the zone boundary determination signals 2a and 2b. “*” Represents a case where the pulse generation interval is smaller than the threshold value. The zone boundary determination signal 1 becomes active when “*” occurs.

  If n = 1, the zone boundary determination circuit 101 detects that the zone boundary determination signal 1 becomes active, and transmits a track jump signal. As a result, the tracking control circuit 88 controls the optical head so that the pickup jumps from the zone boundary.

  Further, the zone boundary determination circuit 101 may determine that the pickup is at the zone boundary when the pulse generation interval is continuously lower than the threshold value two times or more (when n ≧ 2). That is, the zone boundary determination circuit 101 may transmit the track jump signal when “*” in FIG. 16 appears twice or more times (at the time of the pulse P13).

  Furthermore, in the present embodiment, since the zone boundary is determined only by the pulse generation interval, the header detection signal may be either a header detection signal (byRF) or a header detection signal (byTE).

  According to the first embodiment, it can be detected reliably and in a short time that the pickup is at the zone boundary. As a result, it is possible to prevent an increase in seek time by automatically causing the pickup to track jump.

(Second Embodiment)
FIG. 17 is a conceptual diagram showing a zone boundary determination method according to the second embodiment of the present invention. The second embodiment differs from the first embodiment in that an interval from the rising edge of the header detection signal pulse to the rising edge of the second pulse is used. That is, the zone boundary determination circuit 101 measures the generation interval every two pulses. The configuration of the optical disc apparatus of the second embodiment may be the same as that of the first embodiment.

  “One-edge distance 2a” in FIG. 17 indicates a rising interval (referred to as a first pulse generation interval) of odd-numbered pulses P1, P3, P5. “Distance between two edges 2b” indicates a rising interval (referred to as a second pulse generation interval) of even-numbered pulses P2, P4, P6. The “zone boundary determination signal 2a” can be obtained from the “one-edge distance 2a”, and the “zone boundary determination signal 2b” can be obtained from the “one-edge distance 2b”.

  The first and second pulse generation intervals are measured by the period measurement circuit 401 using two measurement counters.

  In zone Z, the first and second pulse generation intervals are both twice the sector length X ± α, that is, 2 × (X ± α). In zone Z + 1, the first and second pulse generation intervals are both twice the sector length Y ± α, that is, 2 × (Y ± α).

  The zone boundary determination unit 403 in FIG. 15 stores the threshold value, and activates (zones) the “zone boundary determination signal 2a” when the first pulse generation interval becomes substantially equal to the threshold value to generate the second pulse. When the interval becomes substantially equal to the threshold value, the “zone boundary determination signal 2b” is made active (high). The threshold value is, for example, (X ± α) or (Y ± α).

  When the pickup enters the zone boundary, the first and second pulse generation intervals become smaller than both 2 × (X ± α) and 2 × (Y ± α). “−” In FIG. 17 represents a case where the pulse generation interval is shorter than 2 × (X ± α) and 2 × (Y ± α) but is equal to or greater than the threshold value. At this time, no pulse is generated in the zone boundary determination signals 2a and 2b.

  A pulse is generated in the zone boundary determination signal 2a when the first pulse generation interval becomes substantially equal to the threshold value (Y ± α). When the second pulse generation interval becomes substantially equal to the threshold (X ± α), a pulse is generated in the zone boundary determination signal 2b ″. The first pulse generation interval and the second pulse generation interval are 2 × (2 × ( A pulse occurs when halving from Y ± α) and 2 × (X ± α).

  When a pulse occurs in either the zone boundary determination signal 2a or 2b, the zone boundary determination circuit 101 generates a track jump signal. Alternatively, the zone boundary determination circuit 101 may generate a track jump signal when a pulse is continuously generated n times in either the zone boundary determination signal 2a or 2b.

  In order to improve the detection accuracy of the zone boundary, the zone boundary determination circuit 101 may determine that the pickup is at the zone boundary when a pulse occurs in both the zone boundary determination signals 2a and 2b. Further, in order to improve the detection accuracy of the zone boundary, the zone boundary determination circuit 101 determines that the pickup is at the zone boundary when the pulse is generated n times continuously in both the zone boundary determination signals 2a and 2b. May be.

  In the second embodiment, either the header detection signal (byTE) or the header detection signal (byTE) may be used.

  As described above, in the second embodiment, the generation interval is measured every two pulses of the header detection signal. At the zone boundary, this interval coincides with the sector length (X ± α or Y ± α) in each zone. Therefore, the second embodiment has a high accuracy of zone boundary determination. Furthermore, the second embodiment has the same effect as the first embodiment.

(Third embodiment)
FIG. 18 is a timing diagram showing a zone boundary determination method according to the third embodiment of the present invention. In the third embodiment, the measurement result of the header width is used for zone boundary determination. As described above, since the header detection signal (byRF) can reproduce the header width more faithfully than the header detection signal (byTE), the header detection signal (byTE) is not used here. In the third embodiment, the pulse width of the detection signal is measured using the header detection signal (byRF). The configuration of the optical disk device of the third embodiment may be the same as that of the first embodiment.

  The pulse width measurement result in FIG. 18 represents the width from the rising edge to the falling edge of the header detection signal pulse. This pulse width is approximately equal to the width of the header area. The “zone boundary determination signal 3” can be obtained from the pulse width measurement result. This pulse width measurement result is obtained from the width measurement circuit 402 in FIG.

  In the zone Z, since the header portions HDR1 and HDR2 are adjacent to each other, the pulse width becomes a value (C ± β) including an error ± β in the width C of the header region HDR0. Also in the zone Z + 1, since the header portions HDR1 and HDR2 are adjacent to each other, the pulse width becomes a value (D ± β) including an error ± β in the width D of the header region HDR0 in the zone Z + 1.

  The zone boundary determination unit 403 in FIG. 15 stores a threshold value, and activates “zone boundary determination signal 3” when the pulse width becomes substantially equal to the threshold value. The threshold is, for example, (C / 2 ± β) or (D / 2 ± β).

  When the pickup enters the zone boundary, the pulse width of the header detection signal becomes smaller than (C ± β). “-” In FIG. 18 represents a case where the pulse width is smaller than (C ± β) but is equal to or larger than the threshold value. At this time, no pulse is generated in the zone boundary determination signal 3.

  Further, when the header portions HDR1 and HDR2 are separated from each other, the pulse width of the header detection signal becomes substantially equal to the threshold value (C / 2 ± β) or (D / 2 ± β). As a result, a pulse is generated in the zone boundary determination signal 3. That is, a pulse is generated when the pulse width of the header detection signal is almost halved from (C ± β) or (D ± β).

  When a pulse is generated in the zone boundary determination signal 3, the zone boundary determination circuit 101 generates a track jump signal. Alternatively, in order to improve the detection accuracy of the zone boundary, the zone boundary determination circuit 101 may generate a track jump signal when a pulse is continuously generated n times in the zone boundary determination signal 3.

  Thus, the third embodiment measures the pulse width of the header detection signal. Since the header portions HDR1 and HDR2 are separated at the zone boundary, the pulse width at the zone boundary is a half of the pulse width in each zone. Therefore, the third embodiment has high accuracy of zone boundary determination. Furthermore, the third embodiment has the same effect as the first embodiment.

The block diagram of DVD-RAM1. The figure which shows the structure of the header area | region vicinity between adjacent recording sectors. The figure which shows the structure of the header area | region vicinity between adjacent recording sectors. The figure which shows arrangement | positioning of the recording sector and header area | region of the boundary area | region of an adjacent zone. The block diagram of the optical disk apparatus 60 according to embodiment which concerns on this invention. FIG. 6 is a circuit diagram showing a configuration of a tracking control circuit 88. 1 is a configuration diagram of a data reproduction circuit 78. FIG. 1 is a configuration diagram of a data reproduction circuit 78. FIG. FIG. 7 is a waveform diagram of a reproduction signal processed by a data reproduction circuit 78. The wave form diagram of various signals in the case of a 2.6 GB disk. The wave form diagram of various signals in the case of a 4.7 GB disk. 2 is a block diagram showing a configuration of a header protection circuit 100. FIG. 2 is a block diagram showing a configuration of a header protection circuit 100. FIG. 4 is a waveform diagram of signals processed by the header protection circuit 100. FIG. FIG. 3 is a block diagram showing a configuration of a zone boundary determination circuit 101. FIG. 3 is a timing chart showing a zone boundary determination method according to the first embodiment of the present invention. The conceptual diagram which shows the zone boundary determination method according to 2nd Embodiment which concerns on this invention. The timing diagram which shows the determination method of the zone boundary according to 3rd Embodiment which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Optical disk apparatus 78, 100 Header detection signal generation part 101 Zone boundary determination part 88 Tracking control circuit HDR0 Header area HDR1 1st header part HDR2 2nd header part

Claims (5)

An optical disc apparatus for recording or reproducing information by irradiating an optical disc medium with a light beam,
A header detection signal generation unit that generates a header detection signal indicating a header region based on a difference signal or a sum signal between a first beam spot and a second beam spot obtained by dividing the light beam into a plurality of parts;
A zone boundary determination unit that determines that the light beam is in a boundary region between zones composed of a plurality of groove tracks and a plurality of land tracks based on a change in the header detection signal;
A tracking control circuit for jumping the light beam to a track other than the boundary region of the zone when the light beam arrives at the boundary region of the zone when the light beam is moved to a certain recording sector; An optical disc apparatus comprising: The zone boundary determination unit
A measuring unit that measures a first distance from a header area to the next header area using the header detection signal, and the light beam is in the zone when the first distance is equal to or less than a predetermined value; 2. The optical disk device according to claim 1, wherein the optical disk device is determined to be in the boundary area of the optical disk. The zone boundary determination unit
Including a measurement unit that measures a first distance from a header area to the next header area using the header detection signal, and counts the number of consecutive times when the first distance is equal to or less than a predetermined value. 2. The optical disc apparatus according to claim 1, wherein when the number of times reaches a predetermined number, it is determined that the light beam is in a boundary region of the zone. The zone boundary determination unit
A measurement unit that measures a distance from the header area to the second header area using the header detection signal, and the optical beam is reduced when the distance is halved from a predetermined value; 2. The optical disc apparatus according to claim 1, wherein the optical disc apparatus is determined to be in a zone boundary region. The zone boundary determination unit
Using the header detection signal, a measuring unit for measuring the length of a certain header area, and determining that the light beam is in the boundary area of the zone when the length of the header area is halved from a predetermined value 2. The optical disk device according to claim 1, wherein

Images