JP4103240B2 - Tracking control method and optical disc apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tracking control method capable of performing stable reproduction of an optical disc accompanied by warpage and surface wobbling in reproducing an optical disc such as a CD and a DVD in the optical disc device, and an optical disc apparatus using the control method.
[0002]
[Prior art]
In an optical disc apparatus, the jitter of a reproduction signal caused by tilt (tilt of the signal recording surface in the optical disc with respect to the laser light emitted from the optical pickup) becomes worse as the recording density of the optical disc increases, resulting in an error in mounting the mechanical parts. The effect of the tilt produced on the jitter is further increased. For this reason, conventionally, in an optical disc apparatus, a tilt adjustment mechanism of an optical pickup that eliminates a tilt caused by attachment of a mechanism component has been used. As an example of such a conventional tilt adjustment mechanism, FIG. 11 shows a mechanism for adjusting the tilt of the optical pickup by adjusting the direction of the guide shaft of the optical pickup. FIG. 11 is a plan view of the main part of a conventional optical disc apparatus.
[0003]
In FIG. 11, the tilt adjustment mechanism of the conventional optical disk apparatus includes an optical pickup 2 that irradiates the optical disk 1 with laser light, two shafts 16 and 17 that guide the optical pickup 2 in the radial direction of the optical disk 1, and one shaft. A tangential direction adjusting screw 18 that is disposed at the end of 16 and adjusts the inclination of the laser optical axis of the optical pickup 2 in the tangential direction of the optical disk; It is the structure provided with the radial direction adjustment screw 19 which performs inclination adjustment in.
[0004]
The optical disk apparatus having the above-described configuration is a mechanism for adjusting the tilt of the optical pickup 2 by raising and lowering the ends of the two shafts 16 and 17 with the two adjusting screws 18 and 19 on the outer peripheral side of the optical disk 1. The tangential adjustment screw 18 adjusts the inclination of the optical axis tangential to the optical axis of the laser beam emitted from the optical pickup 2, and the radial adjustment screw 19 adjusts the inclination of the optical disk in the radial direction. In this way, the tilt is suppressed and the jitter of the reproduction signal is minimized.
[0005]
[Problems to be solved by the invention]
The conventional optical disk apparatus is configured as described above, and tilt adjustment due to an error in attaching the mechanical parts can be suppressed by adjusting the tilt of the optical pickup 2. However, when the optical disk 1 itself has warpage (deformation in the optical disk radial direction) or surface deflection (deformation in the optical disk rotation direction) exceeding the allowable range, tilting occurs at a predetermined laser light irradiation position of the optical disk 1 during reproduction of the optical disk. And the tilt amount greatly changes due to the rotation of the optical disc 1, and the reading is affected by the tilt without being corrected by the conventional adjusting mechanism. In particular, the influence of the tilt in the radial direction of the optical disc 1 becomes serious, and the reflected light The light receiving position of the optical pickup 2 is shifted, the amount of light received is reduced, jitter is increased, and the optical disk cannot be correctly reproduced.
[0006]
The present invention has been made to solve the above problems, and appropriately adjust the laser light irradiation position of the optical pickup according to the tilt of the optical disk in the radial direction caused by warpage or surface deflection of the optical disk, thereby generating jitter. It is an object of the present invention to provide a tracking control method that can suppress and stably read data, and an optical disc apparatus using the control method.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, an optical disc apparatus according to the present invention includes an optical pickup that irradiates an optical disc with laser light and receives laser reflected light from the optical disc, detector means for converting the laser reflected light into an electrical signal, Differential amplifier means for processing a difference signal from the signal to generate a tracking error signal; servo control means for controlling the position of the optical pickup based on the tracking error signal; Jitter detection means for detecting jitter contained in a signal; Focus servo control means for controlling the position of the optical pickup in the focal direction; amplification means for adjusting the frequency component and the signal magnitude from the signal for controlling the focus servo control means; An optical disk apparatus having CPU means for controlling the entire apparatus, wherein the servo control means has tracking correction means for generating a tracking correction signal and supplying the tracking correction signal to the operation amplifier means, and the CPU means places the optical pickup at a predetermined position. After the movement, the jitter is detected by the jitter detection means, and the servo control means generates a tracking correction signal that lowers the jitter based on the jitter value, and repeats until the jitter detected by the jitter detection means is minimized. Generate tracking correction signal Then, the servo control means is operated by superimposing the control signal of the focus servo control means on the generated tracking correction signal via the amplification means. This is an optical disk device characterized by the above.
[0008]
Thereby, even when the optical axis of the reflected light from the optical disk is tilted and deviated due to the tilt of the optical disk due to the warp or surface vibration of the optical disk, the light receiving state of the reflected light by the optical pickup is improved, Stable data reading with less jitter In addition, the optical pickup can be in an appropriate light receiving state even with respect to tilt that changes depending on the position of the optical disk in the rotational direction due to surface shake, etc. An optical disk device that can be used is obtained.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The invention described in claim 1 and claim 4 of the present invention includes an optical pickup that irradiates an optical disc with laser light and receives laser reflected light from the optical disc, detector means for converting the laser reflected light into an electrical signal, A differential amplifier means for generating a tracking error signal by processing a difference signal from an electric signal, and a tracking error signal Optical pickup based Servo control means for controlling the position of the optical disk, and jitter detection means for generating a signal for reading the optical disk from the electric signal and detecting jitter contained in the read signal; A focus servo control means for controlling the position of the optical pickup in the focal direction, and an amplifying means for adjusting the frequency component and the magnitude of the signal from the signal for controlling the focus servo control means; A jitter detection step of detecting jitter by the jitter detection means after the optical pickup is moved to a predetermined position by the servo control means, and the servo control means operates by generating a tracking correction signal based on the jitter value A tracking correction step supplied to the amplifier means, and a jitter minimizing step that repeats the jitter detection step and the tracking correction step until the jitter detected by the jitter detection means is minimized. Then, the servo control unit is operated by superimposing the control signal of the focus servo control unit via the amplification unit on the tracking correction signal determined so as to minimize the jitter by executing the jitter minimizing step. A tracking control method and an optical disc apparatus using the control method.
[0010]
According to the present invention, by adjusting the tracking balance signal by the CPU, the center position of the laser optical axis of the optical pickup is shifted from the track center by a predetermined width to improve the light receiving state of the reflected light, and the tilt of the warped disk or the like in the disk radial direction is improved. Stable data playback with reduced jitter for discs At the same time, stable reproduction of data is performed with the optical pickup in an appropriate light receiving state even with respect to a tilt that changes depending on each position in the rotation direction of the optical disk due to surface shake or the like. It has the action.
[0011]
According to the second and fifth aspects of the present invention, there is provided an adjustment tracking correction step for supplying to the operating amplifier means an adjustment tracking correction signal that is increased or decreased by a predetermined amount with respect to a predetermined tracking correction signal of the tracking correction step. A correction selection step for selecting a tracking correction signal or an adjustment tracking correction signal so that the jitter detected by the jitter detection means becomes a smaller value, and an adjustment tracking correction step and a correction selection at each position in the radial direction of the optical disc. 5. The tracking control method according to claim 1 or 4, and an optical disc apparatus using the control method, wherein the steps are repeated.
[0012]
According to the present invention, the tracking balance signal is controlled by the CPU so that the jitter becomes the minimum value, and the optical pickup moves to the optimum laser beam irradiation center position for a predetermined track during reproduction with respect to the optical disk with warpage. It has the effect of performing stable reproduction of data.
[0013]
According to the third and sixth aspects of the present invention, the jitter minimizing step is executed at each position in the radial direction of the optical disc so as to minimize the jitter corresponding to the address of each position. A first storage step for storing a tracking correction signal in advance; and a second storage step for setting an address range in which jitter is minimized by the tracking correction signal determined in the first storage step. 5. The tracking control method according to claim 1, wherein the servo control means is operated based on the tracking correction signal determined by the first storage step and the second storage step in accordance with the reproduction position of the first and second storage steps. And an optical disc apparatus using the control method thereof.
[0014]
According to the present invention, the optimum value of the tracking balance signal at each track position of the optical disc is stored at the time of start-up before reproduction, and the optimum value of the tracking balance signal stored at the time of optical disc reproduction is given to stabilize the data reproduction at each track position. In addition, the time from access during reading to data reading can be greatly shortened, and the optical disk can be played back more smoothly.
[0017]
Hereinafter, embodiments of the present invention will be described with reference to FIGS. In each figure, components having the same functions as those of the conventional optical disk apparatus are denoted by the same reference numerals.
[0018]
(Embodiment 1)
FIG. 1 is a block diagram of an optical disc apparatus according to Embodiment 1 of the present invention. In FIG. 1, the optical disk apparatus according to the present embodiment includes an optical pickup 2 that irradiates an optical disk 1 with laser light and receives light reflected by the optical disk 1, and a reflection from the optical disk 1 obtained by the optical pickup 2. The light is converted into current, and the A signal, B signal, C signal, and D signal that are output signals for reading data from the optical disc 1 and focus error detection, and the E signal that is an output signal for tracking error detection, and A detector 3 that outputs each electric signal of the F signal, and a differential amplifier 4 that generates a tracking error signal (hereinafter abbreviated as a TE signal) that is a difference signal from the E signal and the F signal output from the detector 3. Have.
[0019]
Further, a TE signal is input from the differential amplifier 4, and based on this TE signal, the tracking actuator 5 that drives the optical pickup 2 is controlled so that the optical pickup 2 follows the track of the optical disk 1 and an F signal is input. A digital servo processor (hereinafter abbreviated as DSP) 6 that generates a tracking balance signal (hereinafter abbreviated as TBAL signal) for adjusting and changing the subtraction ratio of the E signal and the F signal in the differential amplifier 4; The CPU 7 that controls and adjusts the TBAL signal output, the A signal, the B signal, the C signal, and the D signal output from the detector 3 are added, the RF amplifier 8 that generates the RF signal, and the waveform shaping of the RF signal , RF binarized signal (expressed as DATA in FIG. 1) and synchronous clock (expressed as CLK in FIG. 1) Equalizer and PLL circuit 9, DATA and CLK are input, error correction (ECC) circuit 10 that decodes data, and jitter detection that detects jitter from DATA and CLK and outputs the jitter detection state to CPU 7 A circuit 11 is provided.
[0020]
The optical disc apparatus according to the first embodiment has a configuration in which known tilt detection means (not shown) for detecting the tilt state of the optical disc 1 at the irradiated position of the laser beam is disposed. The CPU 7 outputs a predetermined reference value to the DSP 6, and the DSP 6 outputs a TBAL signal for controlling the F signal input. Thus, in a normal state where no tilt is generated at each position of the optical disc 1, when the laser optical axis of the optical pickup 2 is positioned at the track center of the optical disc 1, the E signal and the F signal become equal and the TE signal becomes 0 (tilt). Therefore, the jitter is also minimized.
[0021]
A tracking operation of the optical disk apparatus according to the first embodiment based on the above-described configuration will be described with reference to FIGS. FIG. 2 is an explanatory diagram of a laser optical axis position adjustment state according to the first embodiment of the present invention, and FIG. 3 is an explanatory diagram of a TBAL signal adjustment state at each position in the radial direction of the optical disc according to the first embodiment of the present invention.
[0022]
In FIG. 2, the laser light emitted from the optical pickup 2 has a predetermined spot diameter 13 on the recording surface on which the pits 12 of the optical disk 1 are formed. In the optical disc 1 in which a predetermined angle tilt (tilt) is generated in the radial direction of the optical disc from the plane orthogonal to the laser optical axis due to warpage or the like, the optical axis of the reflected light is tilted and shifted by the tilt, and the light receiving position of the optical pickup 2 is also changed. As a result, the amount of light incident on the detector 3 is reduced.
[0023]
When such a tilt in the laser light irradiation portion is detected, the CPU 7 adjusts the output of the TBAL signal in the DSP 6 while referring to the jitter detection state in the jitter detection circuit 11. Therefore, the F signal input is adjusted based on the TBAL signal, the F signal is increased or decreased by a predetermined amount, and the TE signal output from the differential amplifier 4 is offset controlled. The DSP 6 to which the offset-controlled TE signal is input controls the tracking actuator 5 to move the center position of the laser optical axis of the optical pickup 2 to the tracking target position. Thus, as shown in FIG. 2, within a range where the pit 12 enters the spot diameter 13, the tracking target (position where the jitter is minimized) is shifted from the predetermined track center by a predetermined width in the tilt direction with respect to the laser optical axis. Become.
[0024]
When the track is read out after the movement, the diffuse reflection component of the light from the optical disc 1 caused by the tilt is reduced, the amount of incident light to the detector 3 is increased, and the RF signal generated by the output from the detector 3 is generated. Can be improved.
[0025]
In general, the optical disk 1 has different warp components depending on the position in the radial direction, and the amount of deviation from the center of the laser optical axis of the optical pickup 2 that is desirable for each track position differs. For this reason, as shown in FIG. 3, the above-described output control of the TBAL signal from the DSP 6 by the CPU 7 is also performed for each track of the optical disc 1 so that each track can be read appropriately.
[0026]
As described above, in the present embodiment, the tracking balance (TBAL) signal output from the DSP 6 is controlled by the CPU 7 to offset the tracking error (TE) signal output from the differential amplifier 4, and the laser of the optical pickup 2. Since the center position of the optical axis can be shifted from the track center by a predetermined width to improve the light receiving state of reflected light, jitter can be suppressed and stable against discs that tilt in the radial direction of the disc, such as discs that have warped The data can be reproduced. In FIG. 2, the phase difference method using one beam spot has been described as an example. However, the present invention is not limited to this phase difference method, and the combination of the beam, the detector 3, and the detection signals E and F Needless to say, examples can be applied to the three-beam method and the push-pull method in the same manner. Furthermore, although the example of adjusting the input F signal of the differential amplifier 4 has been described, the same operation is performed even if the input E signal is adjusted.
[0027]
(Embodiment 2)
An optical disc apparatus according to Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 4 is a flowchart of the TBAL signal adjustment process according to the second embodiment of the present invention, and FIG. 5 is a diagram for explaining the relationship between the TBAL signal and jitter according to the second embodiment of the present invention.
[0028]
The optical disc apparatus according to the second embodiment has the same configuration as that of the first embodiment, and reads the laser optical axis of the optical pickup 2 from the center of a predetermined track of the optical disc 1 by a width that minimizes jitter. It is.
[0029]
In the optical disc 1 in which a predetermined angle tilt (tilt) is generated in the radial direction of the optical disc from the plane orthogonal to the laser optical axis due to warpage or the like during reproduction of the optical disc 1, the track center is within the range where the pit 12 enters the spot diameter 13. The diffuse reflection component of the light from the optical disk 1 caused by tilting is reduced at a position deviated from the tilt direction, the amount of incident light on the detector 3 is increased, and the RF signal generated by the output from the detector 3 is improved. There is a position where the jitter can be minimized.
[0030]
Correspondingly, in the optical disc apparatus, the CPU 7 adjusts the output value of the TBAL signal in the DSP 6 while referring to the jitter detection state in the jitter detection circuit 11, and based on this, outputs the TE signal from the differential amplifier 4. Is offset, and the DSP 6 moves the center position of the laser optical axis of the optical pickup 2 by a predetermined width. In this state, the CPU 7 controls the TBAL signal so that the jitter finally detected by the jitter detection circuit 11 based on the A signal, the B signal, the C signal, and the D signal output from the detector 3 is minimized. Is called.
[0031]
The process of obtaining the value of the TBAL signal that minimizes the jitter by the CPU 7 will be described with reference to the flowchart of FIG. 4 taking a three-point sawtooth wave search method as an example. Here, when the value of the TBAL signal is A, the jitter value is expressed as jitter (A).
[0032]
First, in reading at a predetermined track position on the optical disc 1, the CPU 7 gives the initial value A of the TBAL signal, the jitter at TBAL = A is detected by the jitter detection circuit 11, and the CPU 7 determines the jitter value jitter (A). Obtain (Step 1). Next, the TBAL signal is set to TBAL = A + α obtained by adding a predetermined increment α to the initial value A, and the jitter in this case is detected in the same manner, and a jitter value jitter (A + α) is obtained (Step 2).
[0033]
Here, jit (A) and jit (A + α) are compared (Step 3), and if jit (A)> jit (A + α), the TBAL signal is A = A + α and A is replaced with A + α (Step 4). If jit (A) ≦ jit (A + α), A is left as it is.
[0034]
Further, jitter at TBAL = A is detected to obtain jitter (A) (Step 5). Then, the TBAL signal is set to TBAL = A−α obtained by subtracting α from A, and the jitter in this case is detected in the same manner, and the jitter value jitter (A−α) is obtained (Step 6).
[0035]
Here, the comparison is made between jit (A) and jit (A-α) (Step 7). If jit (A)> jit (A-α), the TBAL signal is set to A = A-α and A is set to A-α. Replace (Step 8). If jit (A) ≦ jit (A−α), A is left as it is. Then, it returns to Step1 and repeats the above process (Step1-Step8).
[0036]
In Step 1 and Step 5, the jitter value jit (A) when TBAL = A is measured because the reading position of the optical disc 1 is always changed during data reproduction. Therefore, the jitter value measurement interval associated with reading is measured. And JIT (A) and JIT (A + α) or JIT (A-α) can be compared based on reading of the same position of the optical disc 1 as much as possible, and an appropriate TBAL signal value A can be set. That is why.
[0037]
Here, a supplementary explanation will be given regarding the above operation based on FIG.
[0038]
As described above, in order to repeat the operations from Step 1 to Step 8, jitter measurement is repeated as shown in (1), (2), (3), (4), and (5) in FIG.
[0039]
In (1) and (2) in FIG. 5, since jit (A) <= jit (A + α) and jit (A) <= jit (A−α), the value of A remains unchanged (TBAL = A This is because the position of A has the lowest jitter value, so the portion A is the best jitter point.)
[0040]
Here, in (3) in FIG. 5, since the result measured at Step 5 and Step 6 is jit (A)> jit (A−α) (jitter best point is TBAL = A−α). ), A = A−α (Step 8), and the search position is changed.
[0041]
Further, in (4) (5) in FIG. 5, as in (1) (2), because of jit (A) <= jit (A + α) and jit (A) <= jit (A−α) , A values remain as they are. (Because the position of TBAL = A has the lowest jitter value, the portion A is the best jitter point.)
[0042]
In this way, the value of the TBAL signal always changes while being given the values of A−α, A, and A + α, and when the TBAL signal is A, control is performed so that the jitter becomes the minimum value. During reproduction with respect to the optical disc 1 with warping of different degrees at positions, stable data reproduction can be performed by moving the optical pickup 2 to the optimum laser beam irradiation center position for a predetermined track.
[0043]
(Embodiment 3)
An optical disc apparatus according to Embodiment 3 of the present invention will be described with reference to FIGS.
[0044]
FIG. 6 is a flowchart related to the storage operation of the TBAL signal optimum value at the time of start-up according to the third embodiment of the present invention, and FIG. The optical disc apparatus according to the third embodiment of the present invention has the same configuration as that of the first embodiment, and previously obtains and stores the value of the tracking balance (TBAL) signal that minimizes the jitter at each position of the optical disc 1 at the time of activation. It should be noted that an optimum TBAL signal is given for each stored position when the optical disk 1 is reproduced.
[0045]
The disc reproducing operation of the optical disc apparatus according to the third embodiment will be described with reference to the flowcharts of FIGS. First, the TBAL signal optimum value storing operation at an arbitrary address position of the optical disk at the time of drive activation will be described based on the flowchart of FIG.
[0046]
First, an initial value of the address A of the optical disk 1 is set (Step 11), a tracking operation is performed with the address A as a target, and the value of the TBAL signal that realizes the minimum jitter at this address A is obtained (Step 12). And the calculated optimum value of the TBAL signal are stored in association with each other (Step 13).
[0047]
Next, an address (A + α) separated from the address A by a predetermined address increment α is newly set as A (Step 14), and it is determined whether or not the address A exists inside the outermost periphery (Step 15). If the address A is inside the outermost periphery, the process returns to Step 12 and the operation is repeated (Steps 12 to 14). When the optimum value of the TBAL signal for each address is obtained until the address A does not exist inside the outermost periphery in Step 15, that is, until the outermost periphery, a series of processing is terminated.
[0048]
Next, the reproduction operation for an arbitrary address position on the optical disc 1 will be described based on the flowchart of FIG. As described above, after the optimum value of the TBAL signal at each address is stored at the time of start-up, the reproduction operation is started. First, the optimum TBAL signal value at this address W stored in advance is set for the read start address W. At the same time, the minimum address X and the maximum address Y of the continuous address range of the optical disc 1 where the value of the same TBAL signal is the optimum value that minimizes the jitter are obtained from the stored contents (Step 21).
[0049]
Assuming that the address during data reading at a predetermined time after starting reading from the address W is Z, the address Z is compared with the obtained minimum address X and maximum address Y (Step 22). If it is within the range up to the address Y (X <Z <Y), the value of the TBAL signal is left unchanged and the process is repeated.
[0050]
If the address Z is out of range (Z ≦ X or Z ≧ Y), the optimum TBAL signal value at the previously stored address Z is called and set, and at the same TBAL signal value, the jitter is minimized. The minimum address X and the maximum address Y of the range are newly obtained (Step 23). Thereafter, the process returns to step 22, and similarly, the determination of whether or not the address being read is included in the predetermined address range in which the value of the TBAL signal that minimizes the jitter coincides is repeated.
[0051]
As described above, in the optical disk apparatus shown in the third embodiment, the optimum value of the TBAL signal at each address of the optical disk 1 is stored at the time of activation, and the optimum TBAL signal stored at the time of reproducing the optical disk 1 is given to each address position. Since reading with minimum jitter can be performed, stable data reproduction can be performed, and the time from access to data reading at the time of reproduction can be greatly shortened, so that the optical disk can be reproduced more smoothly.
[0052]
(Embodiment 4)
An optical disc apparatus according to Embodiment 4 of the present invention will be described with reference to FIGS.
[0053]
FIG. 8 is a block diagram of the optical disc apparatus according to the fourth embodiment of the present invention, FIG. 9 is a diagram for explaining the relationship between the focus position and the tilt component in the fourth embodiment of the present invention, and FIG. 10 is the fourth embodiment of the present invention. FIG. 5 is an explanatory diagram of a relationship between a focus drive signal, a tilt, and a TBAL signal.
[0054]
In each figure, the optical disk apparatus according to the fourth embodiment has a focus drive signal output from the DSP 6 to the focus actuator 14 that drives the optical pickup 2 in the focus direction in addition to the same configuration as in the first embodiment. Is also output to the amplifier circuit 15, and the focus drive signal whose frequency component and output magnitude are adjusted by the amplifier circuit 15 is superimposed on the TBAL signal, and the tracking position is adjusted in response to the tilt change in the rotation direction of the optical disc 1. Is.
[0055]
The optical signal reflected by the optical disc 1 is received by the optical pickup 2 and converted and output by the detector 3 into electric signals A, B, C, D, E, and F. In addition, a signal obtained by adding all of the A signal, B signal, C signal, and D signal output from the detector 3 by the RF amplifier 8 becomes an RF signal that is output to the subsequent stage and used for data reproduction. A focus error signal (hereinafter abbreviated as FE signal), which is a difference signal between the signal obtained by adding the C signal and the signal obtained by adding the B signal and the D signal, is generated and input to the DSP 6. The DSP 6 outputs a focus drive signal based on the FE signal to control the focus actuator 14 to drive the optical pickup 2 in the focus direction.
[0056]
Here, when the optical disk 1 with surface wobbling is reproduced, as shown in FIG. 9, the surface of the optical disk 1 is closer to the optical pickup 2 than the optical disk standard position, and the side farther from the optical pickup 2 than the optical disk standard position. In each case, tilts in opposite directions occur in the laser light irradiated position of the optical disc 1 in each case. Since the optical pickup 2 follows the optical disk surface position and is focus-controlled at a predetermined interval from the optical disk 1, the optical pickup 2 has a focus direction position from the reference position to the optical disk standard position with respect to the optical disk 1 having surface wobbling. There is a case where it shifts to the closer side and a case where it shifts to the side far from the standard position of the optical disc.
[0057]
This indicates that the focus drive signal for controlling the focus direction position of the optical pickup 2 also changes corresponding to the tilt of the optical disc 1, as shown in FIG. The output of the optical pickup 2 is superimposed on the TBAL signal while adjusting the output appropriately, and the tracking center is adjusted on the basis of the TBAL signal. Can be shifted to a more appropriate light receiving state, and jitter can be suppressed and stable data reproduction can be performed.
[0058]
【The invention's effect】
As described above, according to the present invention, the tracking balance signal is controlled by the CPU, the tracking error signal is offset, and the center position of the laser optical axis of the optical pickup is shifted from the track center by a predetermined width. Reduces the diffuse reflection component of light and increases the amount of light incident on the detector, improves the light reception state of the reflected light, suppresses jitter, and causes tilting in the radial direction, such as optical discs with warpage and surface shake Stable data playback for optical discs In addition, the optical pickup can be in an appropriate light receiving state even with respect to tilt that changes depending on the position of the optical disk in the rotational direction due to surface shake, etc. An advantageous effect of being able to do this is obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram of an optical disk device according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram of a laser optical axis position adjustment state in the first embodiment of the present invention.
FIG. 3 is an explanatory diagram of TBAL signal adjustment states at respective positions in the optical disc radial direction according to the first embodiment of the present invention.
FIG. 4 is a flowchart of a TBAL signal adjustment process in Embodiment 2 of the present invention;
FIG. 5 is an explanatory diagram of a relationship between a TBAL signal and jitter in Embodiment 2 of the present invention.
FIG. 6 is a flowchart relating to the storage operation of the TBAL signal optimum value at the time of startup according to Embodiment 3 of the present invention;
FIG. 7 is a flowchart relating to a reproducing operation for an arbitrary address position on the optical disc according to the third embodiment of the present invention.
FIG. 8 is a block diagram of an optical disc apparatus according to Embodiment 4 of the present invention.
FIG. 9 is an explanatory diagram of a relationship between a focus position and a tilt component in Embodiment 4 of the present invention.
FIG. 10 is a diagram for explaining the relationship between a focus drive signal, a tilt, and a TBAL signal in Embodiment 4 of the present invention.
FIG. 11 is a plan view of the main part of a conventional optical disc apparatus.
[Explanation of symbols]
1 Optical disc
2 Optical pickup
3 Detector
4 Differential amplifier
5 Tracking actuator
6 DSP
7 CPU
8 RF amplifier
9 Equalizer and PLL circuit
10 Error correction circuit
11 Jitter detection circuit
12 pits
13 Spot diameter
14 Focus actuator
15 Amplifier circuit
16, 17 shaft
18 Tangential direction adjustment screw
19 Radial direction adjustment screw

Claims (6)

An optical pickup for irradiating an optical disc with laser light and receiving laser reflected light from the optical disc, detector means for converting the laser reflected light into an electric signal, and processing a difference signal from the electric signal to generate a tracking error signal Differential amplifier means; servo control means for controlling the position of the optical pickup based on the tracking error signal; and jitter detection for generating a signal for reading an optical disk from the electrical signal and detecting jitter included in the read signal. Means , focus servo control means for controlling the position of the optical pickup in the focal direction, and amplification means for adjusting the frequency component and the signal magnitude from the signal for controlling the focus servo control means ,
A jitter detection step of detecting jitter by the jitter detection means after moving the optical pickup to a predetermined position by the servo control means;
A tracking correction step in which the servo control means generates a tracking correction signal based on the jitter value and supplies the tracking correction signal to the operational amplifier means;
Possess a jitter minimization steps until the jitter detected by the jitter detecting means is minimum repeating said tracking correction step and the jitter detection step,
The servo control means is operated by superimposing the control signal of the focus servo control means via the amplifying means on the tracking correction signal determined so as to minimize jitter by executing the jitter minimizing step. A tracking control method characterized by the above. An adjustment tracking correction step of supplying an adjustment tracking correction signal that is increased or decreased to a predetermined amount with respect to a predetermined tracking correction signal of the tracking correction step to the operating amplifier means;
A correction selection step of selecting the tracking correction signal or the adjustment tracking correction signal so that the jitter detected by the jitter detection means becomes a smaller value,
2. The tracking control method according to claim 1, wherein the correction tracking correction step and the correction selection step are repeated at each position in the radial direction of the optical disc. A first storage step for preliminarily storing the tracking correction signal determined so as to minimize the jitter corresponding to the address of each position by executing the jitter minimizing step at each radial position of the optical disc; ,
A second storage step for setting an address range in which jitter is minimized by the tracking correction signal determined in the first storage step;
2. The tracking control according to claim 1, wherein the servo control means is operated based on the tracking correction signal determined by the first storage step and the second storage step in accordance with the reproduction position of the optical disk. Method. An optical pickup for irradiating an optical disc with laser light and receiving laser reflected light from the optical disc, detector means for converting the laser reflected light into an electric signal, and processing a difference signal from the electric signal to generate a tracking error signal Differential amplifier means; servo control means for controlling the position of the optical pickup based on the tracking error signal; and jitter detection for generating a signal for reading an optical disk from the electrical signal and detecting jitter included in the read signal. Means , focus servo control means for controlling the position of the optical pickup in the focal direction, amplification means for adjusting the frequency component and signal magnitude from the signal for controlling the focus servo control means, and the overall apparatus An optical disk device having CPU means,
The servo control means includes tracking correction means for generating a tracking correction signal and supplying the tracking correction signal to the operation amplifier means,
The CPU means detects the jitter by the jitter detection means after moving the optical pickup to a predetermined position, and generates a tracking correction signal for reducing the jitter to the servo control means based on the jitter value. The tracking correction signal is repeatedly generated until the jitter detected by the jitter detection means is minimized, and the control signal of the focus servo control means is superimposed on the generated tracking correction signal via the amplification means. And operating the servo control means . The CPU means causes the servo control means to generate an increasing / decreasing tracking correction signal that is increased or decreased by a predetermined amount with respect to a predetermined tracking correction signal, and the tracking detection signal is detected so that the jitter detected by the jitter detecting means becomes a smaller value. Control to select the correction signal or adjustment tracking correction signal,
5. The optical disc apparatus according to claim 4, wherein the control is repeated such that the adjustment tracking correction is generated at each radial position of the optical disc and the tracking correction signal or the adjustment tracking correction signal is selected. The CPU means stores in advance the tracking correction signal determined so as to minimize the jitter at each radial position of the optical disc in correspondence with the address of each radial position, and further generates jitter by the tracking correction signal. Address range that operates as a minimum is determined corresponding to the address of each position,
5. The optical disk apparatus according to claim 4, wherein the servo control means is operated based on the tracking correction signal and the address range in accordance with each address of the reproduction position of the optical disk.

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