JP4804391B2 - Tilt correction control device - Google Patents

Description

  The present invention relates to a technique for controlling correction for a radial tilt deviation between an optical disk and a light beam in an optical disk apparatus that records and reproduces information on an optical disk such as a DVD-RAM by a land track / groove track recording method.

  Among various high-density optical disk formats proposed in order to meet the recent demand for higher capacity for optical disks, there are land track / groove track formats (for example, DVD-RAM disks). This format has a land track with a convex structure in which the polarities of tracking control are reversed in the radial direction of the optical disk, and a groove track with a concave structure. These tracks are formed in a spiral shape on the optical disc, and are reproduced after information is recorded on these tracks.

  A header area is provided at the head of the land track or groove track sector. The header area is an area where address information called CAPA (Complementary Allocated Pit Address) is formed. The header area is composed of pre-pits for the purpose of extracting address information regardless of whether the reading optical head is at the groove track position or the land track position. An optical disc has a CAPA1 area and a CAPA2 area as header areas.

  In an optical disk apparatus (such as an optical recording / reproducing apparatus) for recording / reproducing information on an optical disk, focus control for controlling the light beam to be always in a predetermined focused state on the material film, and the light beam always on a predetermined track. Tracking control for controlling scanning correctly is performed in parallel.

In the state where the spot of the light beam is perpendicularly incident on the disk surface (no radial tilt) after the focus control and the tracking control as described above are performed, the both outputs of the photodetector are symmetrical. reflection diffraction distribution is obtained, in a state in which the other La Jiaruchiruto there, the light intensity is shifted between the two outputs of the photodetectors. As a result, when the beam spot is located at the center of the land track or the groove track, the amplitudes of the CAPA1 region and the CAPA2 region are equal.

When a radial tilt occurs with respect to the optical disc, as a conventional technique (for example, refer to Patent Documents 1 and 2), when the light beam passes through the CAPA1 region and the reflected light when the light beam passes through the CAPA1 region, The second RF signal is generated on the basis of the reflected light and the radial tilt described above is corrected based on the generated second RF signal, thereby correcting the radial tilt deviation between the light beam and the track. For this reason, a configuration in which the accuracy of tilt control is further improved has been proposed.
JP 2000-293868 A JP 2000-149296 A

  However, in the conventional optical disc apparatus as described above, the recording / reproduction quality is extremely deteriorated for the optical disc having the land track and the groove track as described above due to the factor of radial tilt.

  In that case, there is a difference in amplitude between the RF component signal obtained from the CAPA1 region and the RF component signal obtained from the CAPA2 region. To control the radial tilt so as to correct the difference, a corresponding difference is generated. Processing time is required.

  Recently, it has been demanded to increase the recording / reproducing speed and random access for such an optical disc apparatus. However, the above-described problem relating to the correction processing speed of the radial tilt deviation meets the demand for increasing the recording / reproducing speed. It is a serious issue.

The present invention solves the above-mentioned conventional problems, can reliably increase the recording / reproducing speed and random access to the optical disc, and can sufficiently meet the market demand for higher recording / reproducing speed. providing a tilt correction control equipment which can realize an optical disk device.

In order to solve the above-mentioned problems, a tilt correction control device according to claim 1 of the present invention is a circular disk body, and is arranged in the disk radial direction from the center of land tracks and groove tracks provided along the disk circumferential direction. Meanwhile with respect to the optical disc having a first pit train provided deviated to the side, and a second pit arrays provided offset from the center of the land track and the groove track on the other side of the disk radial direction, wherein An optical head unit that scans and irradiates a light beam along a land track and a groove track, and a reproduction signal that detects information recorded on the optical disc obtained by scanning and irradiating the light beam by the optical head unit as a reproduction signal a detector, and the RF signal detector for detecting an RF signal based on the reproduction signal, wherein the reproduced signal detector detects the R Based on the RF signal signal detector detects the light beam and the land as a track and a signal indicating the displacement between the groove track, the first CAPA1 signal amplitude and said second pit based on pit row comprising a CAPA portion signal detector for detecting the amount of difference between the signal amplitude of CAPA2 based on columns, and then set a desired first radial tilt in the optical head section, by the CAPA portion signal detector, the It detects the amount of difference between the signal amplitude of the signal amplitude and CAPA2 of CAPA1 on the land track, and detects the amount of difference between the signal amplitude of the signal amplitude and CAPA2 of CAPA1 on the groove track, the first radial tilt set different second radial tilt in the optical head unit and, by the CAPA portion signal detector, said Randotora It detects the amount of difference between the signal amplitude and the signal amplitude of CAPA2 of CAPA1 on click, to detect the amount of difference between the signal amplitude of the signal amplitude and CAPA2 of CAPA1 on the groove track, the first radial tilt and The CAPA section signal detector is configured such that third,..., M-th (m = 4, 5,...) Different radial tilts different from the second radial tilt are set in the optical head section . Accordingly, the each radial tilt of the third to m, and detects the amount of difference between the signal amplitude and the signal amplitude of CAPA2 of CAPA1 on the land track, CAPA1 signal amplitude and CAPA2 signal on the groove track By detecting the amount of difference from the amplitude , the C on the land track detected in each of the first to m-th radial tilts is detected. APA1 signal amplitude and the difference of m data or al linear function approximation determined Me Equation Rutotomoni the signal amplitude of CAPA2, the first to m the groove detected in, respectively, respectively of the radial tilt of A linear function approximate expression is obtained from m pieces of data of the difference between the CAPA1 signal amplitude and the CAPA2 signal amplitude on the track, and the radial tilt at the intersection of the two linear function approximate expressions is determined as the optimal radial tilt. It is detected as a value, and its radial tilt value is set.

Further, the tilt correction control device according to claim 2 of the present invention is a circular disk body, and is provided so as to be shifted from the center of the land track and groove track provided along the circumferential direction of the disk to one side in the disk radial direction. first and pit row has, with respect to the land track and a second optical disk having a pit array which is provided offset from the center of the groove track on the other side of the disk radial direction, along the land track and groove track a reproduction signal detector for detecting an optical head, the light beam information recorded on the optical disk obtained by scanning irradiation of by the optical head section as a reproduction signal for scanning a light beam Te, the reproduction signal an RF signal detector for detecting an RF signal based on the reproduction signal detector detects, the reproduction signal detector detects A wobble signal detector for detecting a wobble signal based on the serial reproduction signal, based on the wobble signal the RF signal or the wobble signal detector detects the RF signal detector detects the light beam and the land A CAPA signal detector for detecting the difference between the signal amplitude of CAPA1 based on the first pit row and the signal amplitude of CAPA2 based on the second pit row as a signal indicating the positional deviation between the track and the groove track And an arbitrary first radial tilt is set in the optical head unit , and the CAPA unit signal detector detects a difference amount between the CAPA1 signal amplitude and the CAPA2 signal amplitude on the land track. as well as to detect the amount of difference between the signal amplitude and the signal amplitude of CAPA2 of CAPA1 on the groove track, the first The radial tilt by setting different second radial tilt in the optical head section, by the CAPA portion signal detector, for detecting the amount of difference between the signal amplitude of the signal amplitude and CAPA2 of CAPA1 on the land track together with the signal amplitude CAPA1 on the groove tracks and detects the amount of difference between the signal amplitude of CAPA2, the first radial tilt and the second different third radial tilt, ..., the m ( m = 4, 5,...) are set in the optical head unit , and the CAPA signal detector detects the radial tilt on the land track for each of the third to mth radial tilts . detects the amount of difference between the signal amplitude of the signal amplitude and CAPA2 of CAPA1, signal amplitude CAPA1 on the groove track and CAPA2 M of by detecting the difference of the signal amplitude, the difference amount between the first to signal amplitude and the signal amplitude of CAPA2 of CAPA1 on the land track detected in, respectively, respectively of the radial tilt of the m pieces of data or al linear function approximation determined Me equation Rutotomoni, the difference between the signal amplitude and the signal amplitude of CAPA2 of CAPA1 on the groove track detected in, respectively, respectively of the radial tilt of the first to m amount seeking of m linear function approximation formula from the data, the radial tilt at the intersection of the two first-order function approximation expression is detected as the optimum radial tilt values, and Turkey set the radial tilt value It is characterized by.

The tilt correction control apparatus according to claim 3 of the present invention is the tilt correction control apparatus according to claim 1 or 2 , wherein the CAPA section signal detector includes the optical disk and the light beam. A signal output from the optical pickup to generate a focus and tracking error signal is used as an RF signal to be detected when measuring a radial tilt deviation amount, or an RF output used to read information on the optical disc is used. characterized in that it is selectably configured whether to use an aS signal obtained by adding.

As described above, an arbitrary first radial tilt (t1) is set in the optical head section , and L1 which is the difference between the CAPA1 signal amplitude and the CAPA2 signal amplitude on the land track is detected. Similarly, the groove track Also in the above, G1 which is the difference between the signal amplitude of CAPA1 and the signal amplitude of CAPA2 is detected.

Next, a second radial tilt (t2) different from the previously set radial tilt is set in the optical head unit , and L2 which is the difference between the CAPA1 signal amplitude and the CAPA2 signal amplitude on the land track is detected. Similarly, G2 which is the difference between the signal amplitude of CAPA1 and the signal amplitude of CAPA2 is also detected on the groove track.

Next, an nth radial tilt (tn) different from the radial tilt set above is set in the optical head unit , and Ln, which is the difference between the CAPA1 signal amplitude and the CAPA2 signal amplitude on the land track, is detected. Similarly, Gn, which is the difference between the CAPA1 signal amplitude and the CAPA2 signal amplitude, is also detected on the groove track.

Here, the signal amplitude difference between CAPA1 and CAPA2 with respect to the radial tilt is approximated to a linear function having a certain inclination. In other words,

RFu · L = a * t + b (Formula 1)
RFu · G = c * t + d (Formula 2)

Can be replaced by In Equations 1 and 2, L and G are the difference in signal amplitude between CAPA1 and CAPA2 of the land track and groove track, t is the radial tilt, and a, b, c, and d are numbers obtained by a linear approximation equation. Represents.

  As described above, the land track / groove track format optical disc such as the DVD-RAM has a structure having a convex land track and a concave groove track in which the polarities of the tracking error signals are reversed in the radial direction of the disc. Therefore, the polarity can be detected by switching the polarity between the land track and the groove track.

By utilizing this fact, the intersection point t = (db) / (ac) of Equation 1 and Equation 2 can be detected as an appropriate radial tilt.
Also, by obtaining the radial tilt value detected as described above at an arbitrary radial position on the optical disk and interpolating it as a radial tilt with respect to the radial position, the acquisition rate of information necessary for reproduction / recording and access is improved. It becomes possible.

  As described above, according to the present invention, the optimal radial tilt value is detected by obtaining the linear function approximate expression obtained from the relationship between the signal amplitude difference amounts of CAPA1 and CAPA2 with respect to the radial tilt for each of the land track and the groove track. By setting the radial tilt value, the time required for stabilizing the radial tilt at the time of access can be shortened, and the radial tilt value can be corrected quickly.

  As described above, it is possible to reliably increase the recording / reproducing speed and random access to the optical disk, and to realize an optical disk apparatus that can sufficiently meet the market demand for higher recording / reproducing speed.

Hereinafter, a tilt correction control apparatus and a tilt correction control method according to an embodiment of the present invention will be specifically described with reference to the drawings.
First, before describing the configuration of the tilt correction control apparatus of the present embodiment, the header area α of the optical disk in the optical disk apparatus incorporating the tilt correction control apparatus will be described.

  As shown in FIG. 8, a header area α is provided at the head of the sector of the land track L or groove track G of the optical disc. The header area α is an area where address information called CAPA (Complementary Allocated Pit Address) is formed. The header area α is composed of pre-pits for the purpose of extracting address information regardless of whether the reading optical head is at the groove track position or the land track position.

  The header area α has a CAPA1 area corresponding to the first pit string and a CAPA2 area corresponding to the second pit string. The CAPA1 area is arranged at the head corresponding to the groove track G of each sector. The CAPA2 area is arranged at the head corresponding to the land track L of each sector. The CAPA1 area and the CAPA2 area are disposed between the land track L and the groove track G adjacent to each other at the head of each sector, but are not provided at the same diameter position of the optical disc, and the land track L and the groove track G are alternately arranged with different radial positions.

The CAPA 1 and 2 areas are composed of Variable Frequency Oscillators 1 and 2 (hereinafter referred to as VFO 1 and 2) and sector addresses 1 and 2, respectively. The VFOs 1 and 2 are recorded at a single frequency, and are used to pull in a Phase Locked Loop (hereinafter referred to as PLL). The sector address 1 provided in the CAPA1 area indicates the address of the corresponding groove track G sector, and the sector address 2 provided in the CAPA2 area indicates the address of the corresponding land track L sector.
(Embodiment)
FIG. 1 is a block diagram showing the configuration of an optical disc apparatus incorporating the tilt correction control apparatus of the present embodiment.

  This optical disk apparatus can divide components into two blocks. That is, the optical disc apparatus includes a disc / optical head unit 100 for irradiating the optical disc 3 with a light beam and receiving reflected light from the optical disc 3, and a tilt control unit 200. The tilt control unit 200 includes a circuit for realizing tilt correction by digital control and a circuit for reading an address.

Hereinafter, the configuration and operation of the disk / optical head unit 100 and the tilt control unit 200 will be described.
(Disk / optical head unit 100)
As shown in FIG. 2, the disk / optical head unit 100 rotates the optical disk 3 as an information recording medium, for example, a disk motor 4 comprising a spindle motor, and an optical head unit 101 for irradiating the optical disk 3 with a light beam. , And a transfer motor 13 which is an example of transfer means for moving the optical head unit 101.

  The optical head unit 101 can constitute a moving unit that moves the light beam in the radial direction of the optical disk 3, and the zone where the light beam is located can be obtained from the position of the optical head unit 101.

  The optical head unit 101 includes a light source 5 such as a semiconductor laser, a coupling lens 6 into which a light beam generated from the light source 5 is sequentially incident, a polarization beam splitter 7, a quarter wavelength plate 8, an objective lens 10, and a tilt actuator 11. And a two-divided photodetector 12 on which the light beam from the optical disk 3 is incident. The optical head unit 101 does not necessarily require the above-described components, and the configuration thereof is shown as an example. In the present embodiment, the tilt actuator 11 and the transfer motor 13 constitute a scanner, and the two-divided photodetector 12 constitutes a reproduction signal detector.

  The tilt actuator 11 is composed of, for example, a movable part having a coil for radial tilt and a fixed part having a permanent magnet. The objective lens 10 is attached to the movable part of the tilt actuator 11. The two-divided photodetector 12 has a light receiving region divided into two, and the direction of the dividing line corresponds to the track direction on the light receiving surface.

The operation of the disk / optical head unit 100 having such a configuration will be described.
The optical disk 3 is rotated at a predetermined rotational speed (rotational speed) by the disk motor 4. The light beam generated from the light source 5 is collimated by the coupling lens 6, passes through the polarization beam splitter 7 and the quarter wavelength plate 8 in this order, and is focused and irradiated onto the optical disk 3 by the objective lens 10. .

  The reflected light of the light beam irradiated on the optical disk 3 passes through the objective lens 10 and the quarter-wave plate 8 in this order, and is reflected by the polarization beam splitter 7 and then irradiated onto the two-split photodetector 12. The two light receiving regions of the two-divided photodetector 12 respectively convert the irradiation light into electrical signals TEP and TEN and RF that is an addition signal of the two-divided photodetector, and output the result to the tilt control unit 200.

The irradiation position of the light beam on the optical disk 3 is adjusted by the transfer motor 13 and the tilt actuator 11. The transfer motor 13 is used when the entire optical head unit 101 is moved in the disc radial direction of the optical disc 3. The tilt actuator 11 changes the relative position of the fixed portion with respect to the permanent magnet by using an electromagnetic force generated according to the current flowing in the coil of the movable portion, thereby allowing light to be adjusted in accordance with the warp (radial tilt) of the optical disc 3. Move the beam.
(Tilt control unit 200)
The tilt control unit 200 includes a TE signal detection circuit 21, an RF signal detection circuit 22, a wobble signal detection circuit 23, a land / groove polarity detection switch (SW) 24, a driver 25, and a CAPA unit signal detection circuit 26. A microcomputer 27, a memory unit 28, and a tilt deviation detection circuit 29.

  The TE signal detection circuit 21 constitutes a tracking error detector. As shown in FIG. 3, the TE signal detection circuit 21 includes a differential circuit 15, a low-pass filter (hereinafter referred to as LPF) 16, and a land / groove polarity detection switch 24. Prepare. The differential circuit 15 calculates a difference between the electric signals TEP and TEN output from the two-divided photodetector 12, passes the difference through the LPF 16, and outputs the difference as a TE signal. The land / groove polarity detection switch 24 outputs a tracking error (TE) signal based on the TRPOL signal supplied from the microcomputer 27.

Here, the TRPOL signal is a signal for determining the output from the land track and the output from the groove track, and is generated by the microcomputer 27.
The land / groove polarity detection switch 24 switches the output based on the TRPOL signal. That is, the land / groove polarity detection switch 24 outputs the output (difference) of the differential circuit 15 corresponding to the groove track G to the inverting amplifier 17 and the output (difference) of the differential circuit 15 corresponding to the land track L. Without passing through the inverting amplifier 17, the TE signal is output as it is.

  The wobble signal detection circuit 23 constitutes a wobble signal detector and includes a differential circuit 18 and a BPF 19 as shown in FIG. The differential circuit 18 outputs a difference between the electrical signals TEP and TEN output from the two-split photodetector 12, and the difference passes through the BPF 19 and is output as a wobble (WBL) signal.

  The RF signal detection circuit 22 constitutes an RF signal detector and includes an addition circuit 20 as shown in FIG. The adder circuit 20 adds the electrical signals TEP and TEN output from the two-divided photodetector 12 and outputs the result as an AS signal. Further, the RF signal added and output in the optical head unit 101 is output as an RF0 signal through the RF signal detection circuit 22.

  The CAPA section signal detection circuit 26 is configured to correct the radial tilt. As shown in FIG. 6, the CAPA section signal detection circuit 26 includes an RF0 / AS / wobble signal selection switch (SW) 47, a high-pass filter (hereinafter referred to as HPF). 40), a punching circuit 41, a VFO amplitude detection circuit 42, a first sample hold circuit 43, a second sample hold circuit 44, and a differential circuit 45.

  The RF0 / AS / wobble signal selection SW 47 is an electric signal RF (RF0, AS) supplied from the two-divided photodetector 12 through the RF signal detection circuit 22 or a wobble signal WBL output from the wobble signal detection circuit 23. Is selected and output to the HPF 40.

The HPF 40 removes the DC component of one signal selected from the RF0 / AS / wobble signal selection SW 47 and outputs the signal to the punching circuit 41.
Based on the CAPA detection signal (CAPA) supplied from the microcomputer 27, the punching circuit 41 extracts the signal RFc in the region corresponding to the header region α (see FIG. 8) in the electric signal RF0 or AS and detects the VFO amplitude. It outputs to the circuit 42. Here, the CAPA detection signal (CAPA) is a signal for determining the header region α (see FIG. 8) in the RF signal, and is generated by the microcomputer 27.

The VFO amplitude detection circuit 42 detects the amplitude RFc ′ from the signal RFc and outputs it to the first and second sample and hold circuits 43 and 44.
The first sample hold circuit 43 extracts the amplitude RFc′1 of the signal region corresponding to VFO1 from the amplitude RFc ′ based on the VFO1 detection signal (VFO1) supplied from the microcomputer 27, and supplies it to the differential circuit 45. Output. Here, the VFO1 detection signal (VFO1) is a signal for determining a signal area corresponding to VFO1 (see FIG. 8) in the electrical signal RF0 or AS, and is generated by the microcomputer 27.

  Based on the VFO2 detection signal (VFO2) supplied from the microcomputer 27, the second sample and hold circuit 44 extracts the amplitude RFc′2 of the signal region corresponding to VFO2 from the amplitude RFc ′, and supplies it to the differential circuit 45. Output. Here, the VFO2 detection signal (VFO2) is a signal for determining a signal area corresponding to VFO2 (see FIG. 8) in the electric signal RF0 or AS, and is generated by the microcomputer 27.

The differential circuit 45 generates a difference between the amplitude RFc′1 and the amplitude RFc′2 and outputs the difference as RFs. Here, RFs corresponds to the amount of radial tilt deviation.
The tilt deviation detection circuit 29 includes a land / groove polarity detection switch 24, an inverting amplifier 50, a gain amplifier 51, and an LPF 52, as shown in FIG.

  The land / groove polarity detection switch 24 switches and outputs the difference signal RFs based on the TRPOL signal supplied from the microcomputer 27. That is, the land / groove polarity detection switch 24 outputs the RFs signal corresponding to the groove track G to the inverting amplifier 50 and outputs the RFs signal corresponding to the land track L to the gain amplifier 51 without passing through the inverting amplifier 50. To do.

  The inverting amplifier 50 inverts the RFs signal corresponding to the groove track G supplied via the land / groove polarity detection switch 24, and then outputs it to the gain amplifier 51.

  The gain amplifier 51 adjusts the gain of RFs supplied from the land / groove polarity detection switch 24 or the inverting amplifier 50 and outputs the gain to the LPF 52. The LPF 52 removes a high frequency component from the output (gain-adjusted RFs) of the gain amplifier 51 and then outputs it as a radial tilt deviation amount RFu.

  Next, changes in the signal waveforms of the electric signal RF and the wobble signal WBL with respect to the change in radial tilt will be described with reference to FIGS. 8 to 10 and FIGS. 12 to 14. For simplicity of explanation, it is assumed that no recording mark is formed on the land track L and the groove track G excluding the header area α, that is, an unrecorded state. The fluctuation of the signal waveform is generated based on the positional consistency (tilt) between the spot (SP) of the light beam output through the objective lens 10 and the tracks L and G.

  When the spot (SP) is located at the track center of each of the tracks L and G and the optical disk 3 is not warped and has no radial tilt as shown in FIG. 12, the amplitude RFc of the electric signal RF in VFO 1 is shown in FIG. “1” is substantially equal to the amplitude RFc′2 in VFO2 (RFc′1−RFc′2 = 0). Such an amplitude difference also occurs in the wobble signal.

  Even when the spot (SP) is located at the track center of each of the tracks L and G, FIG. 9 shows a state in which the optical disc 3 is in the direction approaching the optical head unit 101 toward the outer periphery as shown in FIG. Thus, the amplitude RFc′1 of the electric signal RF in VFO1 is larger than the amplitude RFc′2 in VFO2 (RFc′1−RFc′2> 0). Such an amplitude difference also occurs in the wobble signal.

  Even when the spot (SP) is located at the track center of each of the tracks L and G, FIG. 10 shows a state where the optical disk 3 is moving away from the optical head 101 toward the outer periphery as shown in FIG. Thus, the amplitude RFc′1 of the electric signal RF in VFO1 is smaller than the amplitude RFc′2 in VFO2 (RFc′1−RFc′2 <0). Such an amplitude difference also occurs in the wobble signal.

  Next, details of the operation of the CAPA section signal detection circuit 26 will be described with reference to the waveform diagrams of FIGS. 11, 15 to 17 and FIG. 22. For simplicity of explanation, it is assumed that no recording mark is formed on the land track L and the groove track G excluding the header area α, that is, an unrecorded state.

  As shown in FIG. 11, the microcomputer 27 generates a CAPA detection signal (CAPA) that becomes High (hereinafter referred to as “H”) during the entire period in which the spot (SP) passes through the header region α. Output to. The punching circuit 41 extracts CAPA while the supplied CAPA detection signal (CAPA) is H, and outputs the signal RFc to the VFO amplitude detection circuit 42 as the extraction result. The VFO amplitude detection circuit 42 calculates the amplitude RFc ′ of the signal RFc that is the extraction result of the supplied CAPA, and uses the calculation result (amplitude RFc ′) as the first sample hold circuit 43 and the second sample hold circuit 44. And output.

  Further, as shown in FIG. 11, the microcomputer 27 generates a VFO1 detection signal (VFO1) that rises immediately after the output of VFO1 is completed, and outputs it to the first sample hold circuit 43, and the output of VFO2 is A VFO 2 detection signal (VFO 2) that rises immediately after completion is generated and output to the second sample and hold circuit 44.

  The first sample-and-hold circuit 43 extracts the amplitude RFc ′ at the time when the supplied VFO1 detection signal (VFO1) rises, and consequently extracts the amplitude RFc′1 corresponding to VFO1.

  The second sample and hold circuit 44 extracts the amplitude RFc ′ at the time when the supplied VFO2 detection signal (VFO2) rises, and as a result, extracts the amplitude RFc′2 corresponding to VFO2.

  The differential circuit 45 calculates a difference between the amplitude RFc′1 corresponding to VFO1 output from the first sample hold circuit 43 and the amplitude RFc′2 corresponding to VFO2 output from the second sample hold circuit 44. The calculated difference is output to the tilt deviation detection circuit 29 as RFs. That is, when RFc′1 = RFc′2, the differential circuit 45 outputs zero-level RFs as shown in FIG. When RFc′1> RFc′2, as shown in FIG. 16, the differential circuit 45 has one polarity (for example, + polarity) and determines the difference between the amplitude RFc′1 and the amplitude RFc′2. RFs having a corresponding level are output. When RFc′1 <RFc′2, as shown in FIG. 17, the differential circuit 45 has the other polarity (for example, −polarity) and the difference between the amplitude RFc′1 and the amplitude RFc′2. RFs having a corresponding level are output.

  FIG. 22 shows an RF signal waveform and a wobble signal waveform that are output when a spot (SP) passes through each of the groove track G and the land track L one by one when radial tilt occurs. The feature indicates that the feature appears in the groove track G and the land track L.

Hereinafter, the details of the tilt correction control method in the optical disc apparatus of the present embodiment will be described with reference to the flowchart of FIG.
The following tilt correction control method is basically executed by each circuit based on an instruction from the microcomputer 27.

  First, the focusing operation of the disk motor 4, the light source (laser) 5, and the optical head unit 101 is driven (S101). Next, the tracking operation of the optical head unit 101 is driven (S102). Next, the land / groove polarity detection switch 24 is operated (S103). As a result, RFu can be output.

  Next, in order to set the first radial tilt, a command for setting an arbitrary radial tilt is issued from the microcomputer 27 to the driver 25, and the tilt actuator 11 is moved from the driver 25 by the amount commanded by the microcomputer 27. (S104).

  Next, a still jump is started, and the light beam output through the objective lens 10 is held on the groove track G (S105). Specifically, the light beam output through the objective lens 10 is grooved by setting a still jump command (hereinafter referred to as JMP) output from the microcomputer 27 to the optical head unit 101 to H level for each rotation. The track G is still jumped and held. Then, while performing the still jump (groove), the tilt deviation detection circuit 29 is cleared and the measurement operation is performed. That is, the microcomputer 27 outputs a clear command (hereinafter referred to as “CLR”) and a measurement command START to the tilt deviation detection circuit 29. The tilt deviation detection circuit 29 performs the measurement in response to the command.

  Next, the light beam output through the objective lens 10 traces on the single groove track G, and the tilt deviation detection circuit 29 measures the RFs output from the differential circuit 45, and as a result, RFu. Is output and stored in the memory unit 28 (S106).

  Next, the light beam output through the objective lens 10 is held on the land track L so that the still jump position is located on the land track L (S107). Specifically, the JMP command output from the microcomputer 27 to the optical head unit 101 is set to H level every rotation, so that the light beam output through the objective lens 10 is still jumped to the land track L. Hold. Then, while performing the still jump (land), the tilt deviation detection circuit 29 is cleared and the measurement operation is performed. That is, the microcomputer 27 outputs a CLR command and a measurement command START to the tilt deviation detection circuit 29. The tilt deviation detection circuit 29 performs the measurement in response to the command.

  Next, the light beam output through the objective lens 10 traces on the single groove track L, and the tilt deviation detection circuit 29 measures the RFs output from the differential circuit 45, and as a result, RFu. Is output and stored in the memory unit 28 (S108).

  Next, the set number of radial tilt points for measuring RFu is determined, the RFu amplitude at the set tilt is measured, and when the number of times of measurement is less than the set number of points, the operation of returning to S104 is repeated ( S109). For example, FIG. 19 shows a model when 10 measurement points are set in S104 (m = 10). The operations from S104 to S108 are repeated 10 times (k = 1 to 10), and the set value of RFu as an output from the radial tilt and tilt deviation detection circuit 29 is stored in the memory unit 28.

  Next, RFu · G = c * t + d (Equation 2) is derived from the groove track as a linear approximation line obtained based on the result stored in the memory unit 28, and RFu · L = a * from the land track. t + b (Formula 1) is derived, and a radial tilt t = (db) / (ac) where RFu · G = RFu · L is obtained from these two formulas and stored in the microcomputer 27 (S110). ).

  Finally, the radial tilt value obtained by the measurement / calculation processing from S104 to S110 is set at the measured radial position of the optical disc 3 (S111). As a method of setting the target radial tilt by the microcomputer 27, RFu is obtained from the tilt deviation detection circuit 29 at each of a plurality of land tracks and groove tracks at an arbitrary track position (radial position) of the optical disc 3, and an optimum radial tilt is obtained. Detect (calculate).

  It is necessary to divide the recording area of the optical disc 3 into areas (zones) according to the tilt value measurement location. In FIG. 20, there are seven target radials (0 radius position, 6 radius position, 11 radius position, 17 radius position, 23 radius position, 30 radius position, and 34 radius position) on the optical disk 3 according to the radius position. The tilt value is measured and set.

  In addition, the area between the set plural places (seven places in FIG. 20) may use the radial tilt values located at either end thereof, or separately by linearly interpolating the radial tilt values located at both ends. Although calculation may be performed, linear interpolation is preferably performed in order to increase control accuracy, and this method needs to perform processing based on the flowchart of FIG. 21 obtained by improving the flowchart of FIG.

  The process of the flowchart of FIG. 21 will be described. In this flowchart, in the flowchart of FIG. 18, the process of S201 is added between the process of S103 and the process of S104, and the process of S202 is added between the process of S110 and the process of S111.

In S <b> 201, the optical motor 101 is moved to the target radial position by the transfer motor 13 as the radial position of the optical disk 3.
In step S202, the optical head unit 101 is moved to the divided area of the optical disk 3 (zoned). When p zones are set, S104 to S110 are repeated until the radial tilt value is set at p points.

  As described above, according to the present embodiment, the optimal radial tilt value is obtained by obtaining the linear function approximate expression obtained from the relationship between the signal amplitude difference amounts of CAPA1 and CAPA2 with respect to the radial tilt for each of the land track and the groove track. Is detected and the radial tilt value is set, the time required to stabilize the radial tilt at the time of access can be shortened, and the radial tilt value can be corrected quickly.

  As a result, it is possible to reliably increase the recording / reproducing speed and random access to the optical disk, and to realize an optical disk apparatus that can sufficiently meet the market demand for higher recording / reproducing speed.

Tilt correction control equipment of the present invention, the recording and reproducing speed, random access can be reliably accelerated to an optical disc, realizing an optical disc device capable of sufficiently met the market demand faster recording speed For example, the present invention can be applied to an optical disc apparatus that records and reproduces information on an optical disc such as a DVD-RAM by a land track / groove track recording method.

1 is a block diagram showing a configuration of an optical disc apparatus using a tilt correction control apparatus according to an embodiment of the present invention. 1 is a block diagram showing a configuration of a disk / optical head unit in an optical disk apparatus using the tilt correction control apparatus of the embodiment. 1 is a block diagram showing a configuration of a TE signal detection circuit in an optical disc apparatus using the tilt correction control device of the same embodiment 1 is a block diagram showing a configuration of a wobble signal detection circuit in an optical disc apparatus using the tilt correction control apparatus of the same embodiment 1 is a block diagram showing a configuration of an RF signal detection circuit in an optical disc apparatus using the tilt correction control device of the same embodiment A block diagram showing a configuration of a CAPA section signal detection circuit in an optical disc apparatus using the tilt correction control apparatus of the same embodiment 1 is a block diagram showing a configuration of a tilt deviation detection circuit in an optical disc apparatus using the tilt correction control apparatus of the embodiment State explanatory diagram of RF signal and wobble signal when there is no radial tilt in the optical disc apparatus using the tilt correction control apparatus of the embodiment State explanatory diagram of RF signal and wobble signal when there is a radial tilt in the optical disc apparatus using the tilt correction control apparatus of the embodiment Other states explanatory view of RF signal and wobble signal when there is radial tilt in optical disc apparatus using tilt correction control device of same embodiment State explanatory diagram of RF signal, VFO signal and CAPA signal when there is no radial tilt in the optical disc apparatus using the tilt correction control apparatus of the embodiment State explanatory diagram of the optical head unit when the optical disk is not warped in the optical disk apparatus using the tilt correction control device of the embodiment State explanatory diagram of the optical head unit when the optical disc is warped in the optical disc apparatus using the tilt correction control device of the embodiment Another state explanatory view of the optical head unit when the optical disk is warped in the optical disk apparatus using the tilt correction control device of the same embodiment State explanatory diagram of RF signal, RFc ′ signal and RF s signal when there is no radial tilt in the optical disc apparatus using the tilt correction control apparatus of the embodiment State explanatory diagram of RF signal, RFc ′ signal and RF s signal when there is a radial tilt in the optical disc apparatus using the tilt correction control apparatus of the embodiment Another state explanatory diagram of the RF signal, the RFc ′ signal, and the RF s signal when there is a radial tilt in the optical disc apparatus using the tilt correction control device of the embodiment A flowchart showing a process of a tilt correction control method in an optical disc apparatus using the tilt correction control apparatus of the embodiment Explanatory drawing of the relationship between RFu signal and Tilt (t) in the optical disc apparatus using the tilt correction control apparatus of the embodiment Explanatory drawing of the relationship between Tilt (t) and disc radial position in the optical disc apparatus using the tilt correction control device of the embodiment Flowchart showing another process of the tilt correction control method in the optical disc apparatus using the tilt correction control apparatus of the embodiment State explanatory diagram of RF signal, wobble signal and TRPOL signal when there is a radial tilt in the optical disc apparatus using the tilt correction control apparatus of the embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Optical disk 4 Disc motor 5 Light source 6 Coupling lens 7 Polarizing beam splitter 8 1/4 wavelength plate 10 Objective lens 11 Tilt actuator 12 Two-split photodetector 13 Transfer motor 15 Differential circuit 16 LPF
17 Inverting amplifier 18 Differential circuit 19 BPF
20 addition circuit 21 TE signal detection circuit 22 RF signal detection circuit 23 wobble signal detection circuit 24 land / groove polarity detection SW (switch)
25 Driver 26 CAPA Signal Detection Circuit 27 Microcomputer
28 Memory Unit 29 Tilt Deviation Detection Circuit 30 Laser Control Unit 40 HPF
41 punching circuit 42 VFO amplitude detection circuit 43 first sample and hold circuit 44 second sample and hold circuit 45 differential circuit 47 RF0 / AS / wobble signal selection switch (SW)
50 Inverting amplifier 51 Gain amplifier 52 LPF
100 disc / optical head unit 101 optical head unit 200 tilt control unit

Claims (3)

A circular disc body, a first pit row provided on one side of the disc radial direction from a center of a land track and a groove track provided along the circumferential direction of the disc , and a center of the land track and the groove track An optical head unit that scans and irradiates a light beam along the land track and the groove track with respect to an optical disc having a second pit row that is shifted from the other side in the radial direction of the disc ,
A reproduction signal detector for detecting, as a reproduction signal, information recorded on the optical disc obtained by scanning irradiation of the light beam by the optical head unit ;
An RF signal detector for detecting an RF signal based on the reproduction signal detected by the reproduction signal detector;
Based on the RF signal detected by the RF signal detector, the signal amplitude of the CAPA1 based on the first pit row and the second signal are used as a signal indicating a positional deviation between the light beam and the land track and groove track . a CAPA portion signal detector for detecting the amount of difference between the signal amplitude of CAPA2 based on pit rows,
And an arbitrary first radial tilt is set in the optical head unit , and the CAPA unit signal detector detects the difference amount between the CAPA1 signal amplitude and the CAPA2 signal amplitude on the land track. detects the difference of the signal amplitudes of the signal amplitude and CAPA2 of CAPA1 on the groove track,
A second radial tilt different from the first radial tilt is set in the optical head unit , and the difference between the signal amplitude of CAPA1 and the signal amplitude of CAPA2 on the land track is detected by the CAPA unit signal detector. detects the to detect the amount of difference between the signal signal amplitude of the amplitude and CAPA2 of CAPA1 on the groove track,
A third,..., M-th (m = 4, 5,...) Different radial tilt different from the first radial tilt and the second radial tilt is set in the optical head unit. , by the CAPA portion signal detector, for each radial tilt of the third to m, and detects the amount of difference between the signal amplitude of the signal amplitude and CAPA2 of CAPA1 on the land track, CAPA1 on the groove track by detecting the amount of difference between the signal amplitude of the signal amplitude and CAPA2 of
The first to seek Me a difference of m data or al linear function approximation equation between the signal amplitude of the signal amplitude and CAPA2 of CAPA1 on the land track detected in, respectively, respectively of the radial tilt of the m In addition, a linear function approximation expression is obtained from m pieces of data of the difference amount between the signal amplitude of CAPA1 and the signal amplitude of CAPA2 on the groove track detected in each of the first to m-th radial tilts. A tilt correction control apparatus characterized in that a radial tilt at the intersection of the two linear function approximation equations is obtained and detected as an optimal radial tilt value, and the radial tilt value is set. A circular disc body, a first pit row provided on one side of the disc radial direction from a center of a land track and a groove track provided along the circumferential direction of the disc , and a center of the land track and the groove track An optical head unit that scans and irradiates a light beam along the land track and the groove track with respect to an optical disc having a second pit row that is shifted from the other side in the radial direction of the disc ,
A reproduction signal detector for detecting, as a reproduction signal, information recorded on the optical disc obtained by scanning irradiation of the light beam by the optical head unit ;
An RF signal detector for detecting an RF signal based on the reproduction signal detected by the reproduction signal detector;
A wobble signal detector for detecting a wobble signal based on the reproduction signal detected by the reproduction signal detector;
Based on the RF signal detected by the RF signal detector or the wobble signal detected by the wobble signal detector , a signal indicating a positional deviation between the light beam and the land track and groove track is used as the first signal. A CAPA section signal detector for detecting a difference amount between a signal amplitude of CAPA1 based on a pit string and a signal amplitude of CAPA2 based on the second pit string ;
And an arbitrary first radial tilt is set in the optical head unit , and the CAPA unit signal detector detects the difference amount between the CAPA1 signal amplitude and the CAPA2 signal amplitude on the land track. to detect the amount of difference between the signal amplitude of the signal amplitude and CAPA2 of CAPA1 on the groove track,
A second radial tilt different from the first radial tilt is set in the optical head unit , and the difference between the signal amplitude of CAPA1 and the signal amplitude of CAPA2 on the land track is detected by the CAPA unit signal detector. detects the to detect the amount of difference between the signal signal amplitude of the amplitude and CAPA2 of CAPA1 on the groove track,
A third,..., M-th (m = 4, 5,...) Different radial tilt different from the first radial tilt and the second radial tilt is set in the optical head unit. , by the CAPA portion signal detector, for each radial tilt of the third to m, and detects the amount of difference between the signal amplitude of the signal amplitude and CAPA2 of CAPA1 on the land track, CAPA1 on the groove track by detecting the amount of difference between the signal amplitude of the signal amplitude and CAPA2 of
The first to seek Me a difference of m data or al linear function approximation equation between the signal amplitude of the signal amplitude and CAPA2 of CAPA1 on the land track detected in, respectively, respectively of the radial tilt of the m In addition, a linear function approximation expression is obtained from m pieces of data of the difference amount between the signal amplitude of CAPA1 and the signal amplitude of CAPA2 on the groove track detected in each of the first to m-th radial tilts. determined, the radial tilt at the intersection of the two first-order function approximation expression is detected as the optimum radial tilt values, to set the radial tilt value
Tilt correction control unit according to claim and this. The CAPA section signal detector uses an RF output used to read information on the optical disk as an RF signal to be detected when measuring a radial tilt deviation amount between the optical disk and the light beam. tilt correction control according to claim 1 or claim 2, characterized in that it is selectably configured whether to use an aS signal obtained by adding the signal output from the optical pickup for generating a tracking error signal apparatus.

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