JP2004022097A - Disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a disk device in which a optimum focus offset can be detected surely. <P>SOLUTION: A disk device 10 comprises an pickup 12, a laser beam emitted through an optical lens 14 of the pickup 12 is radiated to a track formed on a recording surface of a magneto-optical disk 56. A TE signal and a RF signal are detected respectively based on the laser beam reflected from the recording surface. For example, in focus adjusting processing, the optical lens 14 is shifted in the direction of an optical axis, and a lens position at which amplitude of the TE signal is made the maximum is specified. On the other hand, a lens position at which the amplitude of the RF signal is made the maximum is specified by shifting the optical lens 14 in the direction of an optical axis based on the lens position at which the amplitude of the TE signal is made the maximum. As a lens position at which the amplitude of the RH signal is made the maximum is specified based on a lens position at which the amplitude of the TE signal is made the maximum, a lens position at which the RF signal is made the maximum surely can be specified even when the offset of the RF signal is largely deviated. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
The present invention relates to a disk drive, and more particularly to, for example, irradiating a track formed on a recording surface of a disk recording medium with laser light through a lens and detecting a tracking error signal and an RF signal based on the laser light reflected from the track. And disk devices.
[0002]
[Prior art]
An example of a conventional disk device of this type is disclosed in Japanese Patent Application Laid-Open No. 2002-157755 [G11B7 / 09] filed on May 31, 2002. This prior art changes a focus offset value set in a register between when a seek process based on a TE (Tracking Error) signal is performed and when a decode process of an RF (Radio Frequency) signal is performed. In addition, a TE signal and an RF signal can be appropriately detected at the time of decoding processing. Specifically, first, a focus offset value at which the amplitude of the TE signal becomes maximum is detected, the RF signal is stored on the recording surface of the disk recording medium while maintaining the offset value, and the amplitude of the RF signal becomes maximum. Has been detected.
[0003]
[Problems to be solved by the invention]
However, in the related art, when detecting the focus offset value at which the amplitude of the RF signal is maximum, the focus offset value is first set to an initial value (= 0), and the detection operation is performed based on the initial value. Therefore, when the optimum focus offset value deviates greatly from the initial value, the RF signal cannot be reproduced from the beginning, and there is a problem that the optimum focus offset value cannot be detected after all.
[0004]
Therefore, a main object of the present invention is to provide a disk device capable of reliably detecting an optimum focus offset value.
[0005]
[Means for Solving the Problems]
The present invention relates to a disk device that irradiates a track formed on a recording surface of a disk recording medium with laser light through a lens and detects a tracking error signal and an RF signal based on the laser light reflected from the track. First lens position specifying means for moving the lens in the axial direction to specify the first lens position at which the amplitude of the tracking error signal is maximum, and moving the lens in the optical axis direction based on the first lens position to obtain the amplitude of the RF signal A second lens position specifying means for specifying a second lens position at which a maximum value is obtained.
[0006]
[Action]
The laser light is applied to a track formed on the recording surface of the disk recording medium through a lens. The tracking error signal and the RF signal are respectively detected based on the laser light reflected from the recording surface. The first lens position specifying means specifies the first lens position at which the amplitude of the tracking error signal is maximum by moving the lens in the optical axis direction. On the other hand, the second lens position specifying means moves the lens in the optical axis direction based on the first lens position specified by the first lens position specifying means to specify the second lens position at which the amplitude of the RF signal becomes maximum. I do.
[0007]
For example, the recording means records a predetermined signal on a recording surface in a state where the lens is disposed at the first lens position, and the second lens position specifying means sets the second lens position based on an RF signal corresponding to the predetermined signal. Identify.
[0008]
【The invention's effect】
According to the present invention, the optimum focus offset of the RF signal is detected using the offset value when the tracking error signal is maximized. Therefore, even when the offset value of the RF signal greatly deviates from the reference value, the RF signal is detected. The signal can be read, and the optimum focus offset value of the RF signal can be reliably detected.
[0009]
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.
[0010]
【Example】
Referring to FIG. 1, a disk device 10 of this embodiment includes an optical pickup (optical system) 12 provided with an optical lens 14. The optical lens 14 is supported by a tracking actuator 16 and a focus actuator 18. The laser light emitted from the laser diode 20 is applied to a recording surface of a magneto-optical disk 56 such as an ASMO (Advanced Storage Magneto Optical Disc) through the optical system components shown in FIG. The magneto-optical disk 54 is mounted on a spindle 56 and is rotated by a spindle motor 58. The magneto-optical disk 54 is a ZCLV (Zone Constant Linear Velocity) type disk, and the number of rotations decreases as the optical pickup 12 moves from the inner circumference to the outer circumference.
[0011]
Referring to FIG. 2, laser light emitted from laser diode 20 is split by grating 22. Thereby, one main beam M and two sub beams S1 and S2 are generated. These beams are applied to a rising mirror 28 via a beam splitter 24 and a collimator lens 26. The beam reflected by the rising mirror 28 is converged by the optical lens 14 and then applied to the recording surface of the magneto-optical disk 56 in the manner shown in FIG. That is, the main beam M is applied to a desired track, and the sub beams S1 and S2 are applied to tracks adjacent to both sides of the desired track. Note that on the recording surface of the magneto-optical disk 56, convex land tracks and concave groove tracks are alternately formed for each track. “L” and “G” shown in FIG. 3 mean a land track and a groove track, respectively.
[0012]
The main beam M and the sub-beams S1 and S2 reflected on the recording surface are returned to the beam splitter 24 via the optical lens 14, the rising mirror 28, and the collimator lens 26, that is, on the reverse path. The main beam M and the sub-beams S1 and S2 incident on the beam splitter 24 are applied to a photodetector 34 through a three-beam type Wollaston prism 30 and a plano-concave lens 32.
[0013]
When the light is emitted from the Wollaston prism 30, the main beam M and the sub beams S1 and S2 are all split into three beams. That is, the main beam M is split into beams Ma, Mb and Mc, the sub beam S1 is split into S1a, S1b and S1c, and the sub beam S2 is split into S2a, S2b and S2c. Beam Ma has the same components as main beam M, but beams Mb and Mc have only the vertical and horizontal deflection components of main beam M, respectively. The same is true for the sub-beams S1 and S2, where the beam S1a (S2a) has the same components as the sub-beam S1 (S2), but the beams S1b (S2b) and S1c (S2c) have the vertical deflection components and It has only a horizontal deflection component.
[0014]
The photodetector 34 is configured as shown in FIG. The beam Ma is detected by the detecting elements 34a to 34d, and the beams Mb and Mc are detected by the detecting elements 34i and 34j, respectively. On the other hand, the beam S1a is detected by the detecting elements 34e and 34f, and the beam S2a is detected by the detecting elements 34g and 34h. On the other hand, the beams S1b, S1c, S2b and S2c are not detected by any of the detection elements.
[0015]
Returning to FIG. 1, the FE signal detection circuit 36 performs an operation according to Equation 1 on the outputs of the detection elements 34a to 34d to detect an FE (Focus Error) signal. Further, the TE signal detection circuit 38 performs an operation according to Expression 2 on the outputs of the detection elements 24a to 24h, and generates a TE (Tracking Error) signal by a DPP (Differential Push Pull) method. Further, the RF signal detection circuit 40 performs an operation according to Equation 3 on the outputs of the detection elements 34i and 34j to detect an RF (Radio Frequency) signal. Note that “A” to “J” in Expressions 1 to 3 correspond to outputs of the detection elements 22a to 22j, respectively.
[0016]
(Equation 1)
FE = (A + C)-(B + D)
[0017]
(Equation 2)
TE = {(A + B) − (C + D)} − α {(E + H) − (F + G)}
[0018]
[Equation 3]
RF = I-J
The FE signal output from the FE signal detection circuit 36 is provided to the adder 44 via the A / D converter 34a. The adder 44 adds the offset value set in the register 46 from the level value of the FE signal, and provides an addition value (addition signal) to a DSP (Digital Signal Processor) 48. The DSP 48 executes a focus servo based on the provided addition signal to generate a focus control voltage. The generated focus control voltage is input to the PWM modulation circuit 50a, and the PWM modulation circuit 50a supplies a PWM signal having a pulse width corresponding to the input focus control voltage to the focus actuator 18. Thereby, the focus, that is, the position (lens position) on the optical axis of the optical lens 14 is adjusted.
[0019]
The TE signal output from the TE signal detection circuit 38 is provided to the DSP 48 via the A / D converter 42b. The DSP 48 performs seek processing or tracking control processing based on the applied TE signal, and generates a tracking actuator control voltage and a sled control voltage. The PWM modulation circuits 50b and 50c generate PWM signals having pulse widths corresponding to the tracking actuator control voltage and the sled control voltage, respectively, and apply the PWM signals to the tracking actuator 16 and the sled motor 52. Thus, the radial position of the optical lens 14 and the rotation speed and rotation direction of the sled motor 52 are controlled.
[0020]
The DSP 48 also detects a focus offset at which the amplitude of the TE signal becomes maximum while the focus servo is being executed. Specifically, different focus offsets are set in the register 44 to execute focus servo, and the amplitude (TE amplitude) of the TE signal corresponding to the focus adjusted by each focus offset is detected. Then, the focus offset OFFSET_TE at which the TE amplitude becomes maximum is determined. That is, the lens position at which the TE amplitude becomes maximum is specified.
[0021]
The RF signal output from the RF signal detection circuit 40 is subjected to a decoding process by the ECC decoder 54 to generate a reproduced signal. The RF signal is also provided to the DSP 48 via the A / D converter 42c. The DSP 48 performs a focus offset determination process on the RF signal in the same manner as described above. That is, different focus offsets are set in the register 44 to execute focus servo, and the amplitude (RF amplitude) of the RF signal corresponding to the focus adjusted by each focus offset is detected. Then, the focus offset OFFSET_RF at which the RF amplitude becomes maximum is determined. That is, the lens position when the RF amplitude becomes maximum is specified.
[0022]
At the time of seek processing, the focus offset OFFSET_TE is set in the register 44, and at the time of decoding processing (at the time of tracking control), the focus offset OFFSET_RF is set in the register 44. Therefore, the focus servo at the time of the seek process is executed based on the FE signal and the focus offset OFFSET_TE, and the focus servo at the time of the decode process is executed based on the FE signal and the focus offset OFFSET_RF. As a result, the focus is controlled so that the amplitude of the TE signal becomes maximum during the seek processing, and the focus is controlled so that the amplitude of the RF signal becomes maximum during the decoding processing.
[0023]
The DSP 48 executes a spindle servo in addition to the focus servo, the tracking servo, and the thread servo. By this servo processing, the rotation of the spindle motor 58 is controlled so that the period of the FG pulse output from the spindle motor 58 indicates a predetermined value.
[0024]
The DSP 48 operates according to the flowcharts shown in FIGS. 5 to 9 when calculating the offset, and operates according to the flowchart shown in FIG. 10 when performing the reproduction process. Although the DSP 48 is actually formed by a logic circuit, a flowchart is used for convenience of explanation.
[0025]
Regarding the calculation of the offset, first, the spindle servo is started in step S1 of FIG. 5, and a magnetic head (not shown) is set at a predetermined position on the magneto-optical disk 56 in step S3. Subsequently, the laser diode 20 is turned on in step S5, and focus servo is started in step S7. The magnetic head is used to record a test signal on a magneto-optical disk.
[0026]
In step S9, the focus balance is adjusted using the TE signal according to the subroutine shown in FIGS. 6 and 7, and the focus offset OFFSET_TE is determined. At this point, since neither the tracking servo nor the thread servo has been started, the irradiation position of the laser beam periodically moves so as to straddle a plurality of tracks under the influence of the eccentricity of the magneto-optical disk 56. Therefore, the TE signal detected by the TE signal detection circuit 38 is a signal that changes in a sine wave shape to the positive electrode side and the negative electrode side.
[0027]
When the processing in step S9 is completed, tracking servo and thread servo are started in each of steps S11 and S13, and prewriting is performed in step S15. That is, a magnetic field is applied to the magneto-optical disk 56 by the magnetic head to record a predetermined test signal (RF signal) from a specific address. In the following step S17, focus balance adjustment using an RF signal is performed in accordance with the subroutine shown in FIGS. 8 and 9, and a focus offset OFFSET_RF is determined. At this point, the tracking servo and the thread servo have been started, and the laser beam accurately traces a track after a specific address after finishing recording the test signal. Therefore, an RF signal corresponding to the recorded test signal is output from the RF signal detection circuit 40.
[0028]
The focus balance adjustment using the TE signal will be described with reference to FIG. First, the maximum amplitude TE_MAX of the TE signal is initialized in step S21, and focus offset = 0 is set in the register 46 in step S23. Subsequently, the focus offset is reduced by one step in step S25 ("1" is subtracted from the set value of the register 46), and the TE amplitude is detected in step S27. In step S29, the detected TE amplitude is compared with the maximum amplitude TE_MAX. If TE amplitude ≦ TE_MAX, the process directly proceeds to step S35, but if TE amplitude> TE_MAX, the current TE amplitude is determined to be the maximum amplitude TE_MAX in step S31, and the current focus offset is determined to be OFFSET_TE in step S33. Then, the process proceeds to step S35.
[0029]
In step S35, it is determined whether or not the current focus offset is a negative limit value (in this embodiment, the initial value of the focus offset (0) -10 steps). If "NO", the processes in steps S25 to S33 are performed. repeat. As a result, the TE amplitude corresponding to each focus offset on the minus side is detected, and the maximum TE amplitude on the minus side and the focus offset when this TE amplitude is obtained are determined as TE_MAX and OFFSET_TE.
[0030]
If "YES" is determined in the step S35, the focus offset is returned to "0" in a step S37 (the set value of the register 46 is returned to "0"), and the focus offset is increased by one step in a step S39 (the register 46). "1" is added to the set value of. In step S41, the TE amplitude is detected, and in the following step S43, the detected TE amplitude is compared with the maximum amplitude TE_MAX. Here, if TE amplitude ≦ TE_MAX, the process directly proceeds to step S49. If TE amplitude> TE_MAX, the current TE amplitude is determined to be the maximum amplitude TE_MAX in step S45, and the current focus offset is determined to be OFFSET_TE in step S47. Then, the process proceeds to step S49.
[0031]
In step S49, it is determined whether or not the current focus offset is a plus-side limit value (in this embodiment, the initial value of the focus offset (0) +10 steps). If "NO", the processes in steps S39 to S47 are repeated. . As a result, the TE amplitudes corresponding to all the focus offsets are detected, the TE amplitude that is the largest of all the detected TE amplitudes is determined as TE_MAX, and the focus offset when this TE_MAX is obtained is Determined as OFFSET_TE.
[0032]
The focus balance adjustment using the RF signal follows a subroutine shown in FIGS. In this subroutine, the maximum amplitude RF_MAX of the RF signal is initialized in step S51, and the focus offset = OFFSET_TE is set in the register 46 in step S53.
[0033]
Here, the value of OFFSET_TE (−10 ≦ OFFSET_TE ≦ + 10 in this embodiment) is set as the initial value of the focus offset when the focus offset of the RF signal is largely deviated (shifted). This is because, when the initial value of the focus offset is started from 0, a specific address cannot be detected and an RF signal cannot be reproduced. In addition, the tendency obtained empirically is that the shift direction of the focus offset of the TE signal is the same as the shift direction of the focus offset of the RF signal.
[0034]
Subsequently, in step S55, the focus offset is reduced by one step ("1" is subtracted from the set value of the register 46), and the RF amplitude is detected in step S57. In step S59, the detected RF amplitude is compared with the maximum amplitude RF_MAX. If RF amplitude ≦ RF_MAX, the process directly proceeds to step S65, but if RF amplitude> RF_MAX, the current RF amplitude is determined to be the maximum amplitude RF_MAX in step S61, and the current focus offset is determined to be OFFSET_RF in step S63. Then, the process proceeds to step S65.
[0035]
In step S65, it is determined whether or not the current focus offset is a negative limit value (in this embodiment, the initial value of the focus offset (OFFSET_TE) −10 steps). If “NO”, the processes in steps S55 to S63 are performed. repeat. As a result, the RF amplitude corresponding to each of the focus offsets on the minus side is detected, and is determined as the maximum RF amplitude on the minus side and the focus offsets RF_MAX and OFFSET_RF when this RF amplitude is obtained.
[0036]
If "YES" is determined in the step S65, the focus offset is returned to the OFFSET_TE in the step S67 (the set value of the register 46 is returned to the value of the OFFSET_TE), and the focus offset is increased by one step in the step S69 (the setting of the register 46). Add "1" to the value). In a step S71, the RF amplitude is detected, and in a succeeding step S73, the detected RF amplitude is compared with the maximum amplitude RF_MAX. Here, if RF amplitude ≦ RF_MAX, the process directly proceeds to step S79. However, if RF amplitude> RF_MAX, the current RF amplitude is determined to be the maximum amplitude RF_MAX in step S75, and the current focus offset is determined to be OFFSET_RF in step S77. Then, the process proceeds to step S79.
[0037]
In step S79, it is determined whether or not the current focus offset is the plus-side limit value (in this embodiment, the initial value of the focus offset (OFFSET_TE) +10 steps). If "NO", the processes in steps S69 to S77 are repeated. . As a result, the RF amplitudes corresponding to all the focus offsets are detected, the maximum RF amplitude among all the detected RF amplitudes is determined as RF_MAX, and the focus offset when this RF_MAX is obtained is OFFSET_RF is determined.
[0038]
Regarding the reproduction processing, first, it is determined whether or not a reproduction command has been given in step S81 of FIG. 10, and if "YES", OFFSET_TE is set in the register in step S83. The focus servo has already been started, and the DSP 48 adjusts the focus based on the addition signal of the FE signal and OFFSET_TE. By performing the focus adjustment in consideration of such OFFSET_TE, the amplitude of the TE signal output from the TE signal detection circuit 38 is maximized.
[0039]
In step S85, the reproduction destination track is sought based on the TE signal having the maximum amplitude. When the irradiation destination of the main beam M reaches one track before the reproduction destination track, "YES" is determined in the step S87, the tracking servo and the thread servo are started in each of the steps S89 and S91, and the OFFSET_RF is set in the step S93. Set in register 46. The DSP 48 adjusts the focus based on the addition signal of the FE signal and OFFSET_RF, whereby the amplitude of the RF signal output from the RF signal detection circuit 40 is maximized.
[0040]
When the irradiation destination of the main beam M reaches the target address, the process proceeds from step S95 to step S97, in which the ECC decoder 54 is activated to perform a reproducing process. When the reproduction process is completed, the process returns. When a signal is discretely recorded by the FAT method or the UDF method, the above-described reproduction processing is repeated many times, and the signal is reproduced intermittently by a predetermined amount.
[0041]
As can be seen from the above description, the laser beam is applied to the recording surface of the magneto-optical disk 56 through the optical system including the optical lens 14. The TE signal and the RF signal are respectively detected by the TE signal detection circuit 38 and the RF signal detection circuit 40 based on the laser light reflected from the recording surface. When performing the seek processing, the DSP 48 controls the focus of the optical lens 14 so that the amplitude of the TE signal becomes maximum, and when performing the decoding processing of the RF signal, the DSP 48 controls the focus so that the amplitude of the RF signal becomes maximum. The focus of the optical lens 14 is controlled.
[0042]
Specifically, the focus servo is executed based on the FE signal detected by the FE signal detection circuit 36 and the focus offset set in the register 46. For this reason, the DSP 48 first specifies the focus offset OFFSET_TE at which the amplitude of the TE signal is maximum and the focus offset OFFSET_RF at which the amplitude of the RF signal is maximum. When a reproduction command is given, the DSP 48 sets the focus offset OFFSET_TE in the register 46 when seeking a desired track, and sets the focus offset OFFSET_RF in the register 46 when detecting an RF signal from the desired track.
[0043]
As described above, since the offset value set in the register 46 is changed according to the operation state, the TE signal can be appropriately detected at the time of the seek processing, and the RF signal can be appropriately detected at the time of the decoding processing. That is, if the optical components such as the grating 22 and the Wollaston prism 30 included in the optical pickup 12 are misaligned, even if the focus is adjusted so that the FE signal becomes zero level, the maximum amplitude of the TE signal and the RF signal is obtained. However, in this embodiment, the focus is controlled so that the amplitude of the TE signal is maximized when performing the seek processing, and the amplitude of the RF signal is maximized when performing the decoding processing of the RF signal. Since the focus is controlled to be as follows, seek processing and decoding processing are appropriately performed.
[0044]
According to this embodiment, the optimal focus offset of the RF signal is detected using the optimal focus offset of the TE signal. Therefore, even when the focus offset of the RF signal is significantly shifted, Can be reproduced, and the optimum focus offset can be reliably detected. Therefore, restrictions on the pickup can be relaxed, and the yield of the pickup and the disk device using the pickup can be improved.
[0045]
Although the tracking error signal is detected by the DPP method in this embodiment, the tracking error signal may be detected by an MPP (Main Push Pull) method instead of the DPP method. In this case, it is not necessary to provide a grating in the optical pickup.
[Brief description of the drawings]
FIG. 1 is a block diagram showing one embodiment of the present invention.
FIG. 2 is an illustrative view showing one portion of a configuration of an optical pickup;
FIG. 3 is an illustrative view showing a state where a main beam and a sub beam are irradiated on a recording surface;
FIG. 4 is an illustrative view showing a configuration of a photodetector;
FIG. 5 is a flowchart showing a part of the operation of the DSP when calculating a focus offset.
FIG. 6 is a flowchart showing another part of the operation of the DSP when calculating the focus offset.
FIG. 7 is a flowchart showing another part of the operation of the DSP when calculating the focus offset.
FIG. 8 is a flowchart showing yet another portion of the operation of the DSP when calculating the focus offset.
FIG. 9 is a flowchart showing another part of the operation of the DSP when calculating the focus offset.
FIG. 10 is a flowchart showing a part of the operation of the DSP when performing a reproduction process.
[Explanation of symbols]
Reference Signs List 10 disk device 12 optical pickup 36 FE signal detection circuit 38 TE signal detection circuit 40 RF signal detection circuit 44 register 48 DSP
54 ... ECC decoder

Claims (2)

A disk device that irradiates a track formed on a recording surface of a disk recording medium with laser light through a lens and detects a tracking error signal and an RF signal based on the laser light reflected from the track,
First lens position specifying means for moving the lens in the optical axis direction to specify a first lens position at which the amplitude of the tracking error signal is maximum, and moving the lens in the optical axis direction based on the first lens position A disk device, comprising: a second lens position specifying unit that moves to specify a second lens position at which the amplitude of the RF signal is maximum. Recording means for recording a predetermined signal on the recording surface with the lens disposed at the first lens position;
2. The disk device according to claim 1, wherein said second lens position specifying means specifies said second lens position based on an RF signal corresponding to said predetermined signal.

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