JP2000268377A - Tracking adjusting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tracking adjusting device capable of appropriately adjusting the offset of a tracking error signal even if the offset of the tracking error signal at the standard position of the objective lens is not 0, or the inclination of the offset of the tracking error signal differs between a case where an objective lens is located on the outer periphery side of a disk and that where the objective lens is located on the inner periphery side. SOLUTION: Even if the inclination of the offset of a tracking error signal differs between a case where an objective lens 4 is located on the outer periphery side of an optical disk 1 and that where the objective lens 4 is located on the inner periphery side, a middle value obtained by a middle value detection means 32 is obtained based on the optimum value of the correction coefficient on the outer periphery side and that on the inner periphery side, thus performing balanced and optimum correction between the outer periphery and inner periphery sides of the optical disk 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus for reproducing or recording information data on an optical disk such as a compact disk, a mini disk, a magneto-optical disk, and a phase change disk as a recording medium, based on a tracking error signal. And a tracking adjustment device for automatically adjusting the tracking state.

[0002]

2. Description of the Related Art Conventionally, a compact disk (hereinafter abbreviated as CD), a mini disk (hereinafter abbreviated as MD), a magneto-optical disk (hereinafter abbreviated as MO), a phase change disk (hereinafter abbreviated as PC), etc., which are recording media. 2. Description of the Related Art In an optical disk device that reproduces or records information data on an optical disk, a tracking adjustment device that automatically adjusts a tracking state based on a tracking error signal when adjusting a tracking state on an optical disk is used.

[0003] As a tracking detection method in such a tracking adjustment device, a method called a far field method (hereinafter abbreviated as FF method) or a push-pull method (hereinafter abbreviated as PP method) has been widely known.
Since the configuration is simple and the utilization efficiency of the laser light amount is higher than that of the three-beam method, it is particularly suitable for a recordable optical disk device requiring a large laser output.

However, when the objective lens is displaced in the radial direction of the optical disk (which may be simply referred to as a disk), the relative position between the reflected light of the light beam from the disk and the light receiving element fixed to the pickup body is designed. And there is a problem that an offset occurs in the tracking error signal. In order to solve this, even if the track position changes due to the eccentricity of the disk or the like, the relative position between the reflected light of the light beam from the disk and the light receiving element fixed to the pickup body is always positioned at the center ( In other words, a traverse mechanism is required to make the pickup body respond rapidly at a high speed according to the eccentricity, so that the objective lens is always positioned at the center of the optical axis of the pickup. I have.

In recent years, according to the relative position (hereinafter abbreviated as the objective lens position) between the reflected light of the light beam generated by the displacement of the objective lens in the radial direction of the disk and the light receiving element fixed to the pickup body. An improved FF method (or PP method) for reducing the offset of the tracking error signal is disclosed in Japanese Patent Application No. 08-0289.
No. 05, etc.

A conventional tracking adjustment device for an optical disk using the improved FF method for tracking error detection will be described below. FIG. 4 is a block diagram showing a configuration of a conventional tracking adjustment device using the improved FF method. In FIG. 4, 1 is an optical disk, 2 is a turntable for fixing the optical disk 1, 3 is a motor for rotating the optical disk 1, 4 is a light beam condensing on a recording surface of the optical disk 1 and collecting reflected light. An objective lens 5 that emits light, a tracking actuator that moves the objective lens 4 in the radial direction of the optical disk 1 so that the light beam follows an information track of the optical disk 1, and 6 is a light spot of light reflected from the information surface of the optical disk 1. Reference numeral 7 denotes a light receiving element comprising a plurality of light receiving cells for receiving the light spot 6, reference numeral 8 denotes a dividing line for dividing the light receiving element 7 into a plurality of light receiving cells substantially perpendicular to a direction corresponding to a track, and reference numeral 9 denotes a light receiving element. This is a dividing line that divides the element 7 into a plurality of light receiving cells substantially parallel to the direction corresponding to the track.

Reference numerals 7A, 7B, 7C and 7D denote light receiving cells divided by dividing lines 8 and 9, and 7A and 7B receive light in an end region with respect to the center of the light spot 6, and 7C and 7D.
Receives light in the middle region with respect to the center of the light spot 6.
Numeral 10 subtracts the output of the light receiving cell 7D from the output of the light receiving cell 7C (difference in the middle area), detects the relative position between the light beam focused on the disk recording surface and the information track, and outputs a tracking error signal. Calculation means, 11 is a light receiving cell 7A
Is subtracted from the output of the light receiving cell 7B (difference in the end area).
Calculating means for detecting the relative position of the light spot 6 on the light receiving element 7 in the disk radial direction (ie, the position from the optical axis center of the objective lens) and outputting an objective lens position signal;
Amplifying means for weighting the output signal (objective lens position signal) of the calculating means 11 by a coefficient Ka (= correction coefficient);
Numeral 13 denotes arithmetic means for subtracting the output of the amplifying means 12 from the output (tracking error signal) of the arithmetic means 10 and outputs a corrected tracking error signal.
Mean value detecting means for detecting an average value (offset) of the corrected tracking error signal outputted by the control means; and 18, a gain setting means for setting the value of the correction coefficient Ka of the amplifying means 12 according to the output of the mean value detecting means 17 , 14 perform tracking compensation means for performing phase compensation or low-frequency compensation on the (corrected) tracking error signal to constitute a tracking control system. 19 performs an automatic adjustment operation for setting a correction coefficient Ka of the amplification means 12. A controller 15 for selecting and outputting the output of the tracking controller 14 and the predetermined voltage Vd in accordance with the output of the controller 19;
Is a driving means for driving the tracking actuator 5 with the output of the selection means 15 as an input.

[0008] The operation of the conventional tracking adjustment device configured as described above will be described below with reference to FIG. FIG. 5 is a characteristic diagram showing the offset (average value) of the tracking error signal with respect to the objective lens position and the objective lens position signal. In FIG. 5, the horizontal axis represents the position of the objective lens, the right side of the figure shows the direction in which the objective lens is displaced toward the outer periphery of the disk, the left side of the figure shows the direction in which the objective lens is displaced inward, and Xd in the figure is automatically adjusted. 2 shows the objective lens position that is forced to be positioned for the purpose. The vertical axis represents the amplitude of each signal. In FIGS. 5A, 5B, and 5C, a, d, f
1 and f2 show the offset characteristics of the tracking error signal before the automatic adjustment, and b, e, g1, and g2 show the offset characteristics of the tracking error signal after the automatic adjustment.
(C) of (A) has shown the objective lens position signal.

In FIG. 5A, ofs1 indicates an offset amount of the tracking error signal at the objective lens position Xd before automatic adjustment, and in FIG. 5B, ofs0.
Represents the offset amount of the tracking error signal at the standard position of the objective lens (mechanical or optical center position of the objective lens). In FIG. 5C, f1 and g1 denote the offset characteristics of the tracking error signal on the outer peripheral side of the objective lens. , F2, and g2 indicate the offset characteristics of the tracking error signal on the inner peripheral side of the objective lens.

In FIG. 4, the light receiving element 7 is
By subtracting the signals in the middle region, a tracking error signal (7C-7D) is obtained, and this signal includes an offset corresponding to the position of the objective lens. Further, the arithmetic means 11 makes a difference between the signals in the end regions of the light receiving element 7 to obtain an objective lens position signal corresponding to the objective lens position (7A-7B). This is multiplied by the correction coefficient Ka by the amplifying means 12 and subtracted from the tracking error signal by the calculating means 13, whereby the offset of the tracking error signal according to the position of the objective lens can be corrected.
Details of this operation are disclosed in Japanese Patent Application No. 8-28905.

Here, when optimizing the correction coefficient Ka of the amplifying means 12 by automatic adjustment, first, a predetermined voltage Vd is selected by the selection means 15 under the control of the controller 19, and the tracking actuator 5 is driven to set the objective lens to a predetermined value. Displaced to position Xd. At this time, assuming that the initial value of the correction coefficient Ka of the amplifying unit 12 is 0, the offset of the tracking error signal output by the calculating unit 13 is represented by a in FIG.
As shown in the figure, a value (ofs) corresponding to the objective lens position Xd
1).

Here, the offset value ofs1 of the tracking error signal is detected by the average value detection means 17, and the amplification means 1 is set by the gain setting means 18 so that this becomes zero.
The value of the correction coefficient Ka is varied (the value of Ka is varied by a predetermined amount until the offset of the tracking error signal becomes substantially zero). As can be seen from the configuration of FIG. 4, the objective lens position signal (FIG.
C) is multiplied by a correction coefficient Ka and subtracted from the tracking error signal (a in FIG. 5A) output by the calculating means 10 to generate a corrected tracking error signal. In the waveform of A), b = a−Ka × c, and when the value of Ka is changed, the slope of the offset of the corrected tracking error signal changes.

Here, the objective lens position signal is shown in FIG.
As shown in c of FIG. 5, the position of the objective lens is the standard position (FIG. 5).
(The center position on the horizontal axis: mechanical or optical center of the objective lens) is “0”, so that even if the correction coefficient Ka is varied, the offset of the tracking error signal at the standard position does not change. Since the tracking offset at the standard position is “0” as shown in FIG. 5A, a in FIG. 5A is rotated around the origin by changing Ka, and as shown in b. Thus, a tracking error signal in which an offset does not always occur regardless of the position of the objective lens can be obtained.

[0014]

However, in the conventional tracking adjusting device as described above, the offset of the tracking error signal at the standard position of the objective lens position is not 0, or the objective lens position is on the outer peripheral side of the disk. In the case where the inclination of the offset of the tracking error signal is different between the tracking error signal and the inner side, the offset of the tracking error signal cannot be corrected correctly.

This will be described below with reference to FIGS. 5B and 5C. FIG. 5B shows an operation when the offset of the tracking error signal at the standard position of the objective lens is not “0”. The tracking error signal before the automatic adjustment has an offset corresponding to the position of the objective lens, and also has a residual offset ofs0 at the standard position of the objective lens, as shown in FIG.
In this state, when the objective lens is displaced to a predetermined position Xd and the value of the correction coefficient Ka is changed so that the offset of the tracking error signal at that time becomes “0”, d in FIG. Position (objective lens position signal = 0)
Since the rotation is made around the point of, the characteristic has a slope of the offset as shown in e, and the offset corresponding to the position of the objective lens cannot be correctly corrected.

FIG. 5C shows an operation in the case where the inclination of the offset of the tracking error signal is different between the outer peripheral side and the inner peripheral side of the disk with respect to the objective lens position. The inclination of the offset according to the position of the objective lens of the tracking error signal by the push-pull method may be different between the outer peripheral side and the inner peripheral side due to the influence of the inclination of the optical axis in the pickup. Here, when the objective lens is displaced to the predetermined position Xd and the value of the correction coefficient Ka is varied so that the offset of the tracking error signal at that time becomes “0”, the offset characteristic on the outer peripheral side becomes as shown in FIG. F1
Can be corrected correctly as g1. However, the offset characteristic on the inner peripheral side cannot be corrected correctly because f2 in FIG. 5C becomes g2.

The present invention solves the above-mentioned conventional problems, in which the offset of the tracking error signal at the standard position of the objective lens is not 0, the case where the objective lens position is on the outer peripheral side of the disc, and the case where the objective lens position is on the inner peripheral side. The present invention provides a tracking adjustment device that can always adjust the correction coefficient optimally and correct the offset of the tracking error signal correctly even when the inclination of the offset of the tracking error signal is different from that in the case of (1).

[0018]

In order to solve the above-mentioned problems, a tracking adjustment apparatus according to the present invention comprises a positioning means for setting a relative position of a light beam and a light receiving means in a disk radial direction by using a light beam moving means. Position detecting means for detecting a value corresponding to the relative position of the light beam and the light receiving means in the radial direction of the disk, and calculating means for outputting a tracking error signal and a tracking error signal corrected by calculating the output of the position detecting means, Correction means for setting a coefficient of the calculation means based on the offset of the tracking error signal at a plurality of positions set by the positioning means, wherein the correction means obtains a plurality of provisional coefficients corresponding to the plurality of positions, By setting a single coefficient by calculation between
Even when the offset of the tracking error signal is different between the outer peripheral side and the inner peripheral side of the disk, optimal correction balanced between the outer peripheral side and the inner peripheral side is performed.

As described above, the inclination of the offset of the tracking error signal when the offset of the tracking error signal at the standard position of the objective lens is not 0, or when the objective lens position is on the outer circumference side and the inner circumference side of the disk. Is different, the correction coefficient is always optimally adjusted, and the offset of the tracking error signal can be correctly corrected.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A tracking adjusting device according to a first aspect of the present invention includes a focusing means for focusing a light beam on an information surface of an optical disc on which information is recorded in a predetermined track form, and the focusing means. A light beam moving means for moving the emitted light beam in a radial direction of the optical disk, a light receiving means for receiving a light spot reflected from the optical disk based on the collected light beam, and A tracking error detection unit that detects a relative position error between the light beam and the track in the disk radial direction by an output from a light spot, and outputs a tracking error signal; and the light beam moving unit and the light beam moving unit. Positioning means for determining a relative position of the disk in the radial direction with respect to the light receiving means at a predetermined position; and a plurality of positions determined by the positioning means. Based on the offset of the tracking error signal obtained in correspondence with, a configuration in which a correcting means for correcting the tracking error signal.

According to a second aspect of the present invention, there is provided a tracking adjusting device, wherein the correcting means comprises: a position detecting means for detecting a value corresponding to a relative position of the light beam and the light receiving means in a disk radial direction; Calculating means for outputting a tracking error signal corrected by an arithmetic operation based on a signal and an output of the position detecting means, and based on an offset of the tracking error signal obtained corresponding to a plurality of positions determined by the positioning means. Thus, the configuration is such that the coefficient at the time of calculation by the calculation means is set.

According to a third aspect of the present invention, there is provided a tracking adjustment device, wherein:
By applying a predetermined driving force to the light beam moving means, the relative position between the light beam and the light receiving means in the disk radial direction is set to a predetermined position. According to a fourth aspect of the present invention, in the tracking adjustment device, the positioning means according to the first or second aspect includes an adding means for adding a predetermined value to the output of the position detecting means, and the light is adjusted based on the output of the adding means. By driving the beam moving means, the relative position between the light beam and the light receiving means in the disk radial direction is set to a predetermined value.

According to a fifth aspect of the present invention, in the tracking adjustment device, the correction means of the second aspect sets a single value as a coefficient of the arithmetic means. According to a sixth aspect of the present invention, in the tracking adjustment device, the correction means determines a plurality of provisional coefficients based on offsets of the tracking error signal obtained corresponding to the plurality of positions determined by the positioning means. The configuration is such that the coefficient of the calculating means is set by calculating between the plurality of provisional coefficients.

According to a fifteenth aspect of the present invention, there is provided a tracking adjustment device, wherein the coefficient at the time of calculation by the calculating means is:
The configuration is a sum of a fixed or switchable analog circuit gain and a digital multiplication coefficient. The tracking adjustment device according to claim 17 is the tracking adjustment device according to claims 2 to 16.
The light-receiving means according to any one of (a) and (b), divides the light spot reflected from the optical disk substantially perpendicularly to a direction corresponding to the track, and divides the light spot into an end region and a middle region with respect to the center. First dividing means, second dividing means for further dividing the end area and the middle area substantially in parallel to a direction corresponding to a track, and dividing by the first dividing means and the second dividing means. A light receiving element having a plurality of light receiving cells for receiving the divided light, and a tracking error detecting means for detecting the output of the plurality of light receiving cells for receiving the light in the middle area divided by the second dividing means. The tracking error signal is detected by the corresponding calculation,
The position detecting means calculates the position of the light beam and the light receiving means in accordance with the relative position of the light beam and the light receiving means in the radial direction of the disk by calculating in accordance with the outputs of the plurality of light receiving cells which receive the light of the end area divided by the second dividing means. It is configured to detect the value.

According to the above configuration, even if the inclination of the offset of the tracking error signal is different between the case where the objective lens is located on the outer periphery and the case where the objective lens is located on the inner periphery, the optimal value of the correction coefficient on the outer periphery is different from the optimum value. By adopting an intermediate value of the optimum values of the correction coefficients on the inner peripheral side, optimal correction balanced between the outer peripheral side and the inner peripheral side is performed. According to a seventh aspect of the present invention, in the tracking adjustment device according to the second aspect, the correction unit is configured to calculate a coefficient of the arithmetic unit based on an offset of a tracking error signal obtained corresponding to a plurality of positions determined by the positioning unit. , A plurality of coefficient values are set, and the plurality of coefficient values are switched according to the output signal of the position detecting means.

The tracking adjusting device according to claim 8 is configured such that the correcting means switches a plurality of coefficient values in accordance with the polarity of the output signal of the position detecting means. The tracking adjustment device according to claim 16 is configured such that the analog circuit gain according to claim 15 is a single value, and the digital multiplication coefficient is a plurality of values that can be switched according to the output signal of the position detection means.

According to the above configuration, the optimum values of the correction coefficients are obtained on the outer circumference side and the inner circumference side, respectively, and switching is performed with the objective lens position signal = 0 as a boundary, whereby the correction is made independently on the outer circumference side and the inner circumference side. I do. According to a ninth aspect of the present invention, in the tracking adjusting device, the correcting means stores an output value from the position detecting means when the relative position between the light beam and the light receiving means in the disk radial direction is a standard position. The configuration is such that a plurality of coefficient values are switched by comparing the output signal of the position detecting means with the stored value.

According to the above arrangement, the optimum values of the correction coefficients are obtained on the outer and inner peripheral sides, respectively, and the correction coefficients are set to the standard position of the objective lens (the position when no driving force is applied to the beam moving means). By switching the level of the objective lens position signal in (1) as a boundary, the coefficient is switched at the correct timing regardless of the level of the objective lens position signal at the standard position of the objective lens.

According to a tenth aspect of the present invention, in the tracking adjusting device, the positioning means according to any one of the first to ninth aspects is characterized in that the relative position between the light beam and the light receiving means in the disk radial direction is the standard position and the optical position. The configuration is such that the position where the beam is deviated toward the inner circumference of the disk and the position where the light beam is deviated toward the outer circumference of the disk are determined. The tracking adjustment device according to claim 11 is the correction device according to claim 1 or claim 2,
The offset of the tracking error signal when the relative position of the light beam and the light receiving means in the disk radial direction is at the standard position, and the offset of the tracking error signal when the light beam is at a position biased toward the inner or outer circumference of the disk. Are corrected so that the tracking error signal is substantially equal to the tracking error signal.

In the tracking adjusting device according to the twelfth aspect, the standard position according to any one of the ninth to eleventh aspects is a position where no driving force is applied to the light beam moving means. A tracking adjustment device according to a thirteenth aspect is configured such that the standard position according to any one of the ninth to the eleventh aspects is a position at which the output signal of the position detection means becomes substantially zero.

According to the above configuration, the offset of the tracking error signal when the objective lens is at the standard position,
By setting the coefficient so that the offset of the tracking error signal at the position deviated to the inner circumference side or the outer circumference side of the disk is equal, even if the offset of the tracking error signal at the standard position is not 0,
Set the correct correction coefficient.

According to a fourteenth aspect of the present invention, there is provided a tracking adjustment device, wherein the correction means according to the second aspect comprises: a change amount of the offset of the tracking error signal obtained corresponding to a plurality of positions determined by the positioning means; Based on the ratio of the change amount of the output signal of the detecting means to the coefficient, the coefficient at the time of calculation by the calculating means is set. According to the above configuration,
By dividing the change amount of the offset of the tracking error signal between the standard position and the outer circumferential or inner circumferential position and the change amount of the output signal of the position detecting means, and obtaining the correction coefficient based on the ratio of each slope, the standard coefficient is obtained. Even when the offset of the tracking error signal at the position is not 0, the inclination of the offset of the corrected tracking error signal is set to 0.

Hereinafter, a tracking adjustment device according to an embodiment of the present invention will be specifically described with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a tracking adjustment device according to an embodiment of the present invention. In FIG. 1, 1
16 to 7A, 7B, 7C, and 7D are the same as those in FIG. Reference numeral 20 denotes A / D conversion means for converting a tracking error signal output from the arithmetic means 13 into a digital value, and reference numeral 21 denotes an average value detection means for detecting an average value (offset) of the tracking error signal output from the A / D conversion means 20. , 22 are A / D conversion means for converting the lens position signal output by the calculation means 11 into a digital value;
Reference numeral 23 denotes second average value detection means for detecting the average value of the lens position signal output from the A / D conversion means 22, 24 denotes a controller for controlling the automatic adjustment operation, and 25 and 26 denote control signal output terminals of the controller 24. There is a switching signal output terminal 25 for performing an automatic adjustment operation or a tracking control operation. Reference numeral 26 designates an objective lens position to be positioned at the time of automatic adjustment, a standard position (here, a position at which no driving force is applied to the objective lens 4; In other words, it is a switching signal output terminal for switching between the mechanical center position of the objective lens 4), the outer peripheral side, and the inner peripheral side.

27 is an output terminal 26 of the controller 24
A selection means for selecting and outputting any of + Vd and 0-Vd as a voltage applied to the tracking actuator 5 in order to perform positioning of the objective lens at the time of automatic adjustment in accordance with the control signal from the control signal. A voltage for displacing the lens toward the outer periphery, -Vd is a voltage for displacing the objective lens toward the inner periphery, and 0 is a voltage for displacing the objective lens to the standard position (in a state where no driving force is applied).

28 is an output terminal 26 of the controller 24
Gain setting means for setting the analog multiplication coefficient Ka of the amplifying means 12 in accordance with the control signal from the control signal and the offset of the tracking error signal output by the average value detecting means 21. 29, 32, 33 29 are gain calculating means for calculating a gain corresponding to the output of the average value detecting means 21, and 30 is calculated according to the offset of the tracking error signal when the objective lens is positioned at the standard position and the outer peripheral side. An output terminal for outputting a gain, 31 is an output terminal for outputting a gain calculated according to the offset of the tracking error signal when the objective lens is positioned at the standard position and the inner circumference side, and 32 is an output terminal of the gain calculating means 29 Intermediate value detecting means for calculating and outputting an intermediate value based on the outputs of the two systems from 30 and 31;
33 selects and outputs one of the two outputs of the gain calculating means 29 and the output of the intermediate value detecting means 32 according to the control signal from the output terminal 26 of the controller 24, and outputs the analog correction signal of the amplifying means 12. Selection means for setting the coefficient Ka.

34 is an output terminal 26 of the controller 24
The change amount of the offset of the tracking error signal and the change amount of the average value of the lens position signal at the standard position and the outer peripheral position of the objective lens are obtained in accordance with the control signal from the objective lens. Find the correction coefficient Kd1,
Also, the amount of change in the offset of the tracking error signal and the amount of change in the average value of the lens position signal at the standard position and the inner peripheral position of the objective lens are obtained, and the digital correction coefficient Kd2 on the inner peripheral side is obtained from the ratio. The correction coefficient calculating means 35, 36, and 37 are constituent elements of the correction coefficient calculating means 34, and 35 is a change for detecting a change amount of the offset of the tracking error signal output from the average value detecting means 21 due to the position of the objective lens. The amount detection means 36 is a second change amount detection means for detecting a change amount of the average value of the objective lens position signal output from the second average value detection means 23 due to the objective lens position, and 37 is a change amount detection means 35. A divider that divides the amount of change in the output tracking error signal offset by the amount of change in the average value of the objective lens position signal output by the second change amount detecting means 36. It is.

The dividing means 37 independently divides the positions of the objective lens on the outer peripheral side and the inner peripheral side, stores the results, and divides the result on the outer peripheral side into a digital correction coefficient Kd1.
From the output terminal 38, and the result of division on the inner peripheral side is output from the output terminal 39 as a digital correction coefficient Kd2. 40 is an output terminal 26 of the controller 24
When the objective lens is at the standard position in accordance with the control signal from the control unit, the storage means for storing the average value of the objective lens position signal output from the second average value detection means 23, and the A / D conversion means 22 Storage means 40 for storing the objective lens position signal to be output
A comparing means 42 for comparing the output of the dividing means 42 with the output of the comparing means 41 and selecting one of the digital correction coefficients Kd1 and Kd2 outputted by the dividing means 42 in accordance with the output of the comparing means 41; Is multiplication means for multiplying the output of the selection means 42 as a digital correction coefficient Kd by the objective lens position signal output by the A / D conversion means 22 and outputting the result; 44 is multiplication based on the tracking error signal output by the A / D conversion means 20 Subtraction means for subtracting the output of the means 43 and outputting a digitally corrected tracking error signal.

The tracking adjustment device of the embodiment configured as described above will be described below with reference to FIGS. FIG. 2 is a characteristic diagram showing the characteristics of the offset of the analog corrected tracking error signal output from the A / D conversion means 20 with respect to the position of the objective lens. FIG. 3 is the offset of the digital corrected tracking error signal output from the subtraction means 44. FIG. 4 is a characteristic diagram showing characteristics of an objective lens position signal and an objective lens position.

2 and 3, the horizontal axis represents the position of the objective lens, the vertical axis represents the level of each signal, the right side of the figure represents the direction in which the objective lens is displaced toward the outer periphery, and the left side of the figure represents the inner periphery. Xd and -Xd in the figure indicate the objective lens positions forcibly positioned by the controller 24 for automatic adjustment, the upper side of the figure shows the positive side of the signal level, and the lower side shows the Indicates the negative side.

In FIG. 2, (A), (B), (C),
(D) shows the offset characteristic of the tracking error signal obtained by digitizing the tracking error signal, which has been analog-corrected by the analog correction coefficient Ka of the arithmetic means 12, with the A / D conversion means 20, and (A) shows the analog correction coefficient Ka.
In the case of = 0, (B) shows the result of positioning the objective lens on the outer peripheral side (+ Xd) and optimal adjustment of the analog correction coefficient Ka, and (C) shows the positioning of the objective lens on the inner peripheral side (-Xd).
d) to adjust the analog correction coefficient Ka optimally,
(D) shows the result of setting the analog correction coefficient Ka to an intermediate value between the adjustment results of (B) and (C). Here, it is assumed that the inclination of the offset of the tracking error signal is different between the inner peripheral side and the outer peripheral side of the objective lens position in any case due to the influence of the inclination of the optical axis in the pickup. In the drawing, ofs0 indicates the offset level of the tracking error signal subjected to analog correction at the standard position of the objective lens.

In FIG. 3, (A), (C) and (D) are offsets of the tracking error signal (output of the subtraction means 44) digitally corrected by the digital multiplication coefficient Kd of the multiplication means 43 according to the position of the objective lens. (A) shows the case where the digital correction coefficient Kd = 0,
(C) shows the objective lens on the outer peripheral side (+ Xd) and the inner peripheral side (−Xd).
Xd), and the digital correction coefficients Kd1 and Kd2 were determined for each of them, and correction was performed. As a result, (D) added a constant offset correction to (C) irrespective of the position of the objective lens. The results are shown. (B) shows the objective lens position signal. -Xd2 in the figure indicates the objective lens position at which the level of the objective lens position signal (B) becomes "0", and TEofs0, TEofs1, and TEofs.
2 indicates that the objective lens is at the standard position and the outer peripheral position (+ X
d) indicates the offset level of the tracking error signal at the inner peripheral position (−Xd), and ΔTE1 is TEof
difference between s1 and TEofs0 (TEofs1-TEofs)
0) and ΔTE2 indicate the difference between TEofs2 and TEofs0 (TEofs2-TEofs0). LPofs
0, LPofs1, and LPofs2 indicate that the objective lens has a standard position, an outer peripheral position (+ Xd), and an inner peripheral position (−X
d) indicates the offset level of the objective lens position signal, ΔLP1 is the difference between LPofs1 and LPofs0 (LPofs1-LPofs0), and ΔLP2 is LPo
difference between fs2 and LPofs0 (LPofs2-LPofs
0). TEofs3 indicates the offset level of the tracking error signal when the objective lens position is at the standard position in (C).

In the present embodiment, first, the tracking error signal output from the calculating means 10 is analog-corrected by the correction coefficient Ka of the amplifying means 12, and the signal is digitized by the A / D converting means 20. Further, digital correction is performed by the correction coefficient Kd of the multiplication means 43. The adjustment value of the analog correction coefficient Ka is a single value, but the digital correction coefficient Kd has two adjustment values Kd1 and Kd2 in which the objective lens position is independent on the outer peripheral side and the inner peripheral side. Switch. Such a switching process is more suitable for digital processing than an analog circuit, and can be easily realized by software using a DSP or the like. By combining the analog correction and the digital correction in this way, the analog correction adjusts the offset of the tracking error signal according to the objective lens to fall within a predetermined range, secures the bit accuracy of the A / D conversion means, and In the correction, more accurate correction is performed.

The above operation will be described in detail below. First, the initial value of the analog correction coefficient Ka of the amplifier 12 is set to 0. At this time, the offset characteristic of the tracking error signal output from the A / D converter 20 is as shown in FIG. Here, the output terminal 25 of the controller 24
The selection means 15 selects the output of the selection means 27 in accordance with the control signal from. The selection means 27 selects 0 according to the control signal from the output terminal 26 of the controller 24. As a result, no driving force is applied to the tracking actuator 5, and the objective lens 4 is positioned at the standard position. In this state, the average value (ofs0 in FIG. 2A) of the tracking error signal output from the A / D conversion unit 20 is obtained by the average value detection unit 21. Next, according to a control signal from the output terminal 26 of the controller 24, the selecting means 2
7 selects and outputs a predetermined voltage + Vd. As a result, the tracking actuator 5 is driven in accordance with the predetermined voltage + Vd, and the objective lens 4 is positioned at a predetermined outer peripheral side position + Xd. In this state, the average value of the tracking error signal output from the A / D conversion means 20 is obtained by the average value detection means 21. When this is compared with the previously measured ofs0, it is larger than ofs0 (positive side) as shown in FIG. 2 (A), so that the analog correction coefficient Ka of the amplifying means 12 is varied until the value becomes equal to ofs0. I do.

Specifically, first, the output of the output terminal 30 of the gain calculating means 29 is selected and output by the selecting means 33.
The gain calculating means 29 outputs a gain coefficient from the output terminal 30 and varies this value until the average value of the tracking error signal when the objective lens position is + Xd becomes equal to ofs0, and holds the result at the output terminal 30. I do. Correction coefficient K
When a is changed, as described in the conventional example, the offset characteristic of the tracking error signal rotates around the objective lens position where the objective lens position signal level becomes zero. If the objective lens position signal becomes 0 when the objective lens is at the standard position as in the conventional example (see c in FIG. 5A), the offset characteristic shown in FIG. Since the objective lens is rotated to the center, as shown in FIG. 8B, the offset of the objective lens from the standard position to the outer peripheral side is eliminated according to the objective lens position, and the objective lens has only a constant value (ofs0) independent of the objective lens position. Thus, instead of setting the offset of the track error signal when the objective lens position is + Xd to 0, the offset of the standard position (TEof)
By setting the analog correction coefficient Ka so as to be equal to s), FIG.
It is possible to eliminate an offset corresponding to the position of the objective lens as seen in the characteristic e in FIG. If the offset is a constant offset that does not depend on the position of the objective lens, the offset value can be detected and subtracted, and can be easily corrected by other correction means.

However, at this stage, since the offset characteristics of the tracking error signal are originally different between the outer peripheral side and the inner peripheral side of the objective lens position, an offset corresponding to the objective lens position remains on the inner peripheral side. Next, the value of the analog correction coefficient Ka is set to 0 again. The selection means 27 selects and outputs a predetermined voltage −Vd according to a control signal from the output terminal 26 of the controller 24. As a result, the objective lens 4 is positioned at the predetermined inner peripheral position -Xd. In this state, the average value of the tracking error signal output from the A / D conversion means 20 is obtained by the average value detection means 21. Comparing this with the offset ofs0 when the objective lens measured earlier is at the standard position, as shown in FIG.
Since it is smaller than ofs0 (negative side), the analog correction coefficient Ka is varied until it becomes equal to ofs0.

Specifically, first, the output of the output terminal 31 of the gain calculating means 29 is selected and output by the selecting means 33.
The gain calculating means 29 outputs a gain coefficient from the output terminal 31 and varies this value until the average value of the tracking error signal when the objective lens position is -Xd becomes equal to ofs0, and the result is output to the output terminal 31. Hold. Correction coefficient K
When a is varied, the offset characteristic shown in FIG.
The objective lens rotates around the standard position, and the offset is constant (ofs0) regardless of the objective lens position on the inner peripheral side from the standard position as shown in FIG.
Becomes However, since the offset characteristics of the tracking error signal are different between the outer peripheral side and the inner peripheral side of the objective lens position, an offset corresponding to the objective lens position remains on the outer peripheral side.

Next, in response to a control signal from the output terminal 26 of the controller 24, the intermediate value detecting means 32 outputs the signal to the outer peripheral side held at the output terminals 30 and 31 of the gain calculating means 29,
The average value of the gain on the inner circumference side is detected and output, and this is selected and output by the selection means 33, which is used as the analog correction coefficient Ka in the amplification means 12. As a result, the offset characteristic of the analog-corrected tracking error signal according to the position of the objective lens is, as shown in FIG.
The characteristics are intermediate between (B) and (C), and the characteristics are balanced on the outer peripheral side and the inner peripheral side of the objective lens. In this state, when the absolute value of the position of the objective lens is considered within a certain range (for example, in the range from + Xd to -Xd), it is apparent that the offset of the tracking error signal is minimized.
When the correction coefficient Ka is a single value, the correction state is also a desirable correction state.

Thus, the adjustment of the analog correction coefficient Ka of the tracking error signal is completed. Next, adjustment of the digital correction coefficient Kd will be described. Analog correction coefficient Ka
Is adjusted properly, first, the initial value of the digital correction coefficient Kd of the multiplication means 43 is set to 0. At this time, the offset characteristic of the tracking error signal output from the subtracting means 44 according to the position of the objective lens is as shown in FIG. In the analog correction, if the offset characteristics on the outer peripheral side and the inner peripheral side are adjusted to completely balance, in FIG. 3A, TEofs1 = TEofs2, ΔT
E1 should be equal to ΔTE2, but here, TEofs1 ≠ TEofs, assuming that a slight error remains.
2, ΔTE1 ≠ ΔTE2. The selection means 27 outputs 0 according to a control signal from the output terminal 26 of the controller 24.
Select Thereby, the objective lens 4 is positioned at the standard position.

In this state, first, an average value (TEofs0 in FIG. 3A) of the tracking error signal output from the A / D conversion means 20 is obtained by the average value detection means 21, and further, the second average value detection means 23 The average value of the objective lens position signal output from the A / D conversion means 22 (L in FIG. 3B).
(Pofs0) is obtained and stored in the storage means 40. Next, according to a control signal from the output terminal 26 of the controller 24,
The selection means 27 selects and outputs a predetermined voltage + Vd. Thereby, the objective lens 4 is positioned at a predetermined outer peripheral side position + Xd. In this state, the average value detecting means 21
The average value (TEofs1 in FIG. 3A) of the tracking error signal output from the / D conversion means 20 is obtained, and the second
The average value of the objective lens position signal output from the A / D conversion means 22 by the average value detection means 23 (LPo in FIG. 3B)
fs1).

The change amount detecting means 35 detects the position of the objective lens +
Offset TEo of tracking error signal in Xd
fs1 and the difference ΔTE1 (= TE) between the offset TEofs0 of the tracking error signal at the standard position and the objective lens.
ofs1−TEofs0), and the second change amount detecting means 36 detects the offset LPofs1 of the objective lens position signal at the objective lens position + Xd and the offset LPof of the objective lens position signal at the standard position of the objective lens.
The difference ΔLP1 (= LPofs1-LPofs0) of s0 is detected. The dividing means 37 calculates the offset change ΔTE of the tracking error signal output from the change detecting means 35.
1 is divided by the offset change amount ΔLP1 of the objective lens position signal output from the second change amount detection means 36, and is output from the output terminal 38 as a digital correction coefficient Kd1 on the outer peripheral side.

Kd1 = ΔTE1 / ΔLP1 Equation (1) By performing correction using Kd1 obtained in this manner, the offset of the tracking error signal when the objective lens position is on the outer peripheral side becomes as shown in FIG. As shown in the figure, the offset component according to the position of the objective lens disappears, and a constant value (TEofs3) independent of the position of the objective lens is obtained. This is the offset of the tracking error signal (FIG. 3A)
And the objective lens position signal (FIG. 3B) are each considered as a linear function of the objective lens position, and the inclination is obtained. When the ratio is used as a correction coefficient, the inclination of the offset of the tracking error signal becomes zero. This will be described in detail below using equations.

When the objective lens position is x and the digital correction coefficient Kd = 0, the offset of the tracking error signal (FIG. 3A) is TE (x), and the objective lens position signal (FIG. 3B) is LP ( x), assuming that the offset of the tracking error signal after digital correction is TE ′ (x), TE (x) and LP (x) are approximately proportional to the position of the objective lens, and are expressed by the following linear functions. be able to.

TE (x) = (ΔTE1 / Xd) × x + TEofs0 Expression (2) LP (x) = (ΔLP1 / Xd) × x + LPofs0 Expression (3) As shown in FIG. x) is the digital correction coefficient K
Since it is corrected by multiplying d1 and subtracting from TE (x), TE ′ (x) = TE (x) −Kd1 × LP (x) Expression (4) Expressions (1), (2), ( Substituting 3) into equation (4), TE ′ (x) = (ΔTE1 / Xd) × x + TEofs0− (ΔTE1 / ΔLP1) × ((ΔLP1 / Xd) × x + LPofs0) = TEofs0− (ΔTE1 / ΔLP1) × LPofs0 = TEofs3 Equation (5) According to equation (5), the digitally corrected tracking error signal has no offset component corresponding to the objective lens position x, and has a constant value (TEo) independent of the objective lens position.
fs3).

As described above, the objective lens is positioned at the standard position and the outer or inner circumference side, and the amounts of change of the tracking error signal and the objective lens position signal in that case are obtained, and the correction coefficient is obtained based on the ratio between them. In addition, since only the inclination component of the offset of the tracking error signal can be canceled, the method described above for calculating the analog correction coefficient Ka (the offset of the tracking error signal when the objective lens is positioned on the outer circumference or the inner circumference is set to the standard position) In the same manner as in the case where the offset is made equal to the offset), correct offset correction is possible even when the offset of the tracking error signal at the standard position is not 0, and it is necessary to perform the run-in adjustment by changing the coefficient little by little. Adjustment is completed by one division, so automatic adjustment It is possible to shorten the time significantly.

As described above, the digital correction coefficient Kd1 for the outer peripheral side of the objective lens is obtained. Next, an inner peripheral digital correction coefficient Kd2 is obtained. As in the case of the outer peripheral side, the selecting means 27 selects the predetermined voltage −Vd according to the control signal from the output terminal 26 of the controller 24 to position the objective lens 4 at the predetermined inner peripheral side position −Xd. The average value (TEofs2 in FIG. 3A) of the tracking error signal output from the A / D conversion means 20 is obtained by
The average value of the objective lens position signal output from the A / D conversion means 22 by the average value detection means 23 (LPo in FIG. 3B)
fs2).

The change amount detecting means 35 detects the position of the objective lens.
Offset TEo of tracking error signal in Xd
fs2 and the difference ΔTE2 (= TE) between the offset TEofs0 of the tracking error signal at the standard position and the objective lens.
ofs2−TEofs0), and the second change amount detection unit 36 detects the offset LPofs2 of the objective lens position signal at the objective lens position −Xd and the offset LPof of the objective lens position signal at the standard position of the objective lens.
The difference ΔLP2 (= LPofs2-LPofs0) of s0 is detected. The dividing means 37 calculates the offset change ΔTE of the tracking error signal output from the change detecting means 35.
2 is divided by the offset change amount ΔLP2 of the objective lens position signal output from the second change amount detecting means 36, and the inner peripheral side digital correction coefficient Kd2 (= ΔTE2 / ΔLP)
Output from the output terminal 39 as 2).

By correcting using Kd2 obtained in this way, the offset of the tracking error signal when the objective lens position is on the inner peripheral side becomes an offset component corresponding to the objective lens position as shown in FIG. Is constant, and does not depend on the position of the objective lens (TEofs3)
Becomes Thus, the digital correction coefficients Kd1 and Kd2 on the outer peripheral side and the inner peripheral side are obtained.

Next, these two coefficients are switched in accordance with the level of the objective lens position signal to correct the tracking error signal. Specifically, the objective lens position signal output from the A / D conversion unit 22 is stored in the storage unit 40 (the value L of the objective lens position signal at the standard position of the objective lens).
Pofs0) and the comparing means 41 at all times, and when the objective lens position signal level is larger than LPofs0 (when the objective lens is located on the outer peripheral side), the selecting means 42 outputs the signal from the output terminal 38 of the dividing means 37. When the objective lens position signal level is smaller than LPofs0 (when the objective lens is located on the inner peripheral side), the output from the output terminal 39 of the dividing means 37 is selected by the selecting means 42. The correction coefficient Kd2 on the inner peripheral side is selected and output. As a result, FIG.
As shown in (B), even when the objective lens position signal at the standard position is not 0, the coefficient on the outer peripheral side and the coefficient on the inner peripheral side can be correctly switched with the standard position of the objective lens as a boundary.

If the coefficients are simply switched in accordance with the positive / negative of the objective lens position signal, the coefficients Kd1 and Kd2 are switched at the position of -Xd2 shown in FIG. 3B. As a result, the objective lens position is shifted from the standard position by −
In the range up to Xd2, Kd1 should be used, whereas Kd1 should be used. Therefore, an error occurs in offset correction.

The multiplying means 43 uses the correction coefficient Kd1 obtained on the outer peripheral side when the objective lens is located on the outer peripheral side and the correction coefficient Kd2 obtained on the inner peripheral side when the objective lens is located on the inner peripheral side as a multiplication coefficient. The optimum correction is performed independently for each. This allows
The digitally corrected tracking error signal is shown in FIG.
As shown in (C), the offset component according to the position of the objective lens always disappears regardless of the position of the objective lens on the outer peripheral side / inner peripheral side, and becomes a constant value independent of the objective lens position.

As described above, if the offset does not depend on the position of the objective lens, it can be easily corrected by other correction means such as detecting and subtracting the offset value. ) Offset characteristics easily (D)
The characteristic can be corrected to the following characteristic, and an ideal tracking error signal in which an offset does not always occur regardless of the position of the objective lens can be obtained.

As described above, in the present embodiment, the objective lens is positioned at the standard position, the outer peripheral side and the inner peripheral side of the disk by applying a predetermined voltage to the tracking actuator. By adopting the intermediate value of the analog correction coefficient Ka obtained on the inner circumference side, even when the inclination of the offset of the tracking error signal is different between the outer circumference side and the inner circumference side, optimal correction in which the outer circumference side and the inner circumference side are balanced is achieved. It is also possible to determine the optimum values Kd1 and Kd2 of the digital correction coefficients on the outer and inner circumferences, respectively, and switch them according to the objective lens position signal to thereby obtain the offset characteristics of the tracking error signals on the outer and inner circumferences. Even if the values are different, it is possible to independently and optimally correct the outer circumference and the inner circumference. The optimum value of the coefficient is obtained, and the objective lens switches the position detection signal level at the standard position as a boundary value, thereby irrespective of the level of the objective lens position signal at the standard position, regardless of the level of the tracking error signal on the outer and inner peripheral sides. Even when the characteristics are different, it is possible to independently and optimally correct the outer peripheral side and the inner peripheral side,
In addition, by adjusting the analog correction coefficient Ka so that the offset of the tracking error signal on the outer peripheral side or the inner peripheral side becomes equal to the offset at the standard position, correct offset correction can be performed even when the offset of the tracking error signal at the standard position is not zero. In addition, by setting a digital correction coefficient based on the ratio of the amount of change in the offset of the tracking error signal and the amount of change in the position detection signal at the standard position and the outer or inner peripheral position, tracking at the standard position is possible. Even when the offset of the error signal is not 0, correct offset correction can be performed, and at the same time, since the run-in adjustment is not required, the automatic adjustment time can be significantly reduced.

In the embodiment of the present invention, the objective lens is positioned and adjusted at the standard position, the outer peripheral position, and the inner peripheral position. However, the present invention is not limited to these three positions. Any position may be used. For example, two positions, a standard position and an outer peripheral or inner peripheral position, may be two positions on the outer peripheral side and the inner peripheral side, or three or more positioning positions at the time of adjustment may be used.
Switching may be performed by learning one or more coefficients.

When the offset of the tracking error signal before correction is measured, the initial values of the analog correction coefficient ka and the digital correction coefficient Kd shown in FIG. Although the measurement was performed using the later signal, the amplification means 12 and the multiplication means 4 were structurally configured.
The same applies when measurement is performed using a signal (for example, an output signal of the arithmetic unit 10) before being corrected in step 3.

In performing the automatic adjustment, the initial values of the analog correction coefficient Ka and the digital correction coefficient Kd are set to 0. However, the initial values are not necessarily 0, and a standard coefficient value is set in advance as an initial value. Automatic adjustment may be performed on the above, or if the coefficient value is obtained on the outer peripheral side first, when adjusting on the inner peripheral side next, the coefficient value previously obtained on the outer peripheral side is used as an initial value. Is also good.

In the analog correction, the average value of the coefficient value obtained on the outer circumference side and the coefficient value obtained on the inner circumference side is adopted. However, the average value is not necessarily required. Accordingly, various calculation methods can be considered as long as the values are intermediate values between the outer peripheral side and the inner peripheral side. In addition, the positioning of the objective lens is performed by applying a predetermined voltage to the tracking actuator, but a feedback loop for controlling the position of the objective lens by driving the tracking actuator by performing processing such as phase compensation on the objective lens position signal. Alternatively, a method may be used in which a target point for position control is shifted by adding a predetermined offset to the objective lens position signal to position the objective lens at a predetermined position.

In this case, it is desirable to switch between the coefficient obtained on the outer peripheral side and the coefficient obtained on the inner peripheral side of the objective lens with the objective lens position signal = 0 as a boundary. In this case, the denominator for calculating the correction coefficient by division is:
It is not the amount of change of the objective lens position signal actually measured,
The offset amount added to the objective lens position signal (that is, the change amount of the target position) can be used instead.

Further, in this embodiment, as shown in FIG. 1, the tracking error signal and the objective lens position signal are detected by the calculation based on the output of the light receiving element 7 divided into six parts. The present invention is not limited to the above-described configuration, and the gist of the present invention does not change at all using any detection method as long as the configuration corrects the offset of the tracking error signal according to the position of the objective lens.

The light receiving element 7 in FIG. 1 of the present embodiment may be an element such as a photodetector or the like, which directly receives light reflected from a disk, or may be an element such as a hologram.

[0070]

As described above, according to any one of claims 1 to 6, or claim 15 or claim 17, a disc for a light beam and a light receiving means is provided by using a light beam moving means. Positioning means for setting the relative position in the radial direction, position detecting means for detecting a value corresponding to the relative position of the light beam and the light receiving means in the disk radial direction, and correction by calculation of the tracking error signal and the output of the position detecting means. Calculating means for outputting a tracking error signal, and correcting means for setting a coefficient of the calculating means based on the offset of the tracking error signal at a plurality of positions set by the positioning means. By calculating a plurality of provisional coefficients corresponding thereto and setting a single coefficient by an operation between the provisional coefficients, tracking errors occur on the outer circumference side and the inner circumference side of the disk. Even if the offset of the signals are different, it is possible to perform optimal correction was balanced by an outer peripheral side and inner peripheral side.

According to the invention described in claim 7, claim 8, or claim 16, a plurality of coefficients corresponding to a plurality of positions are set, and these coefficients are output to the output signal of the position detecting means. By switching accordingly, even when the offset of the tracking error signal is different between the outer peripheral side and the inner peripheral side of the disk, the outer peripheral side and the inner peripheral side can be independently and optimally corrected.

According to the ninth aspect of the present invention, a plurality of coefficients corresponding to a plurality of positions are set, and at the same time, the output value of the position detecting means at the standard position of the objective lens is stored. By switching the plurality of coefficients by comparing the output signals of the position detecting means, the coefficients can be switched at the correct timing regardless of the level of the objective lens position signal at the standard position of the objective lens.

According to the tenth aspect of the present invention, the offset of the tracking error signal when the objective lens is at the standard position and the position biased toward the inner or outer circumference of the disk. By setting the coefficient so that the offset of the tracking error signal at the reference position is substantially equal to the offset, the correct correction coefficient can be set even when the offset of the tracking error signal at the standard position is not zero.

According to the fourteenth aspect of the present invention,
By setting a coefficient based on the ratio between the amount of change in the offset of the tracking error signal at a plurality of positions and the amount of change in the output signal of the position detection means, even if the offset of the tracking error signal at the standard position is not zero, At the same time you can set the correction factor,
The automatic adjustment time can be greatly reduced.

Therefore, when the offset of the tracking error signal at the standard position of the objective lens is not 0,
Even if the inclination of the offset of the tracking error signal is different between the case where the objective lens position is on the outer circumference side and the case where it is on the inner circumference side, the correction coefficient is always optimally adjusted and the offset of the tracking error signal is correctly corrected. be able to.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a tracking adjustment device according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing characteristics of each signal in the embodiment.

FIG. 3 is another characteristic diagram showing characteristics of each signal in the embodiment.

FIG. 4 is a block diagram showing a configuration of a conventional tracking adjustment device.

FIG. 5 is a characteristic diagram showing characteristics of each signal in the conventional example.

[Explanation of symbols]

6 light spot 7 light receiving element 7A (light receiving end area of light spot) light receiving cell 7B (light receiving end area of light spot) light receiving cell 7C (light receiving middle area of light spot) light receiving cell 7D (light receiving area) Light receiving cell 8 for receiving light in the middle area 8 Dividing light spot perpendicular to the direction corresponding to the track 9 Dividing line 9 Dividing the light spot in parallel with the direction corresponding to the track 12 Dividing line 12 Amplifying means 21 average value detecting means 23 second average value detecting means 32 intermediate value detecting means 35 change amount detecting means 36 second change amount detecting means 37 dividing means 40 storage means 43 (giving a digital correction coefficient) Multiplication means

Claims (17)

[Claims] 1. A light condensing means for converging a light beam on an information surface of an optical disc on which information is recorded in a predetermined track form, and a light beam for moving the condensed light beam in a radial direction of the optical disc. Moving means, light receiving means for receiving a light spot reflected from the optical disk based on the condensed light beam, and a disk radial direction between the light beam and the track by an output of the light spot from the light receiving means Tracking error detecting means for detecting a relative position error of the optical disc and outputting a tracking error signal; and using the light beam moving means to set a relative position of the light beam and the light receiving means in a disk radial direction to a predetermined position. Positioning means, and an offset of the tracking error signal obtained corresponding to a plurality of positions determined by the positioning means And a correcting means for correcting the tracking error signal based on the tracking error signal. And a correction unit configured to calculate a position of the light beam based on a relative position between the light beam and the light receiving unit in a radial direction of the disk, and a tracking error signal and an output of the position detection unit. Calculating means for outputting the tracking error signal, and setting a coefficient at the time of calculation by the calculating means based on the offset of the tracking error signal obtained corresponding to the plurality of positions determined by the positioning means. The tracking adjustment device according to claim 1, wherein: 3. The positioning device according to claim 1, wherein a predetermined driving force is applied to the light beam moving device to set a relative position between the light beam and the light receiving device in a disk radial direction at a predetermined position. Alternatively, the tracking adjustment device according to claim 2. 4. The positioning means includes an adding means for adding a predetermined value to the output of the position detecting means, and driving the light beam moving means based on the output of the adding means,
3. The tracking adjustment device according to claim 1, wherein a relative position between the light beam and the light receiving unit in the disk radial direction is set to a predetermined value. 5. The tracking adjustment device according to claim 2, wherein the correction means sets a single value as a coefficient of the calculation means. 6. The correction means obtains a plurality of provisional coefficients based on the offsets of the tracking error signal obtained corresponding to the plurality of positions determined by the positioning means, and calculates by calculating the plurality of provisional coefficients. 6. The tracking adjustment device according to claim 5, wherein a coefficient of the means is set. 7. The correcting means sets a plurality of coefficient values as coefficients of the calculating means based on offsets of the tracking error signal obtained corresponding to the plurality of positions determined by the positioning means. 3. The tracking adjustment device according to claim 2, wherein the coefficient value is switched according to the output signal of the position detection means. 8. The tracking adjustment device according to claim 7, wherein the correction means switches a plurality of coefficient values according to the polarity of the output signal of the position detection means. 9. The correction means stores an output value from the position detection means when a relative position of the light beam and the light reception means in the disk radial direction is a standard position, and outputs an output signal of the position detection means to the storage value. 8. The tracking adjustment device according to claim 7, wherein a plurality of coefficient values are switched by comparing with the value of. 10. The positioning means includes a standard position, a position where the light beam is deviated toward the inner circumference of the disc, and a position where the light beam is deflected toward the outer circumference of the disc as relative positions of the light beam and the light receiving means in the disk radial direction. The tracking adjustment device according to claim 1, wherein the tracking adjustment device is set. 11. The correction means includes: an offset of a tracking error signal when a relative position of a light beam and a light receiving means in a disk radial direction is a standard position; and a position at which the light beam is biased toward the inner circumference or the outer circumference of the disk. 3. The tracking adjustment device according to claim 1, wherein the tracking error signal is corrected such that an offset of the tracking error signal in the case of (1) is substantially equal to the tracking error signal. 12. The tracking adjustment device according to claim 9, wherein the standard position is a position where no driving force is applied to the light beam moving means. 13. The tracking adjustment device according to claim 9, wherein the standard position is a position where an output signal of the position detection means becomes substantially zero. 14. A correction means based on a ratio between a change amount of an offset of a tracking error signal obtained corresponding to a plurality of positions determined by the positioning means and a change amount of an output signal of the position detection means. 3. The tracking adjustment device according to claim 2, wherein a coefficient at the time of calculation by the calculation means is set. 15. The tracking adjustment apparatus according to claim 2, wherein the coefficient at the time of the calculation by the calculation means is a sum of a fixed or switchable analog circuit gain and a digital multiplication coefficient. 16. The tracking adjustment device according to claim 15, wherein the analog circuit gain is a single value, and the digital multiplication coefficient is a plurality of values that can be switched according to an output signal of the position detecting means. 17. A first light receiving means for dividing a light spot reflected from an optical disk substantially perpendicularly to a direction corresponding to a track, and dividing the light spot into an end region and a middle region with respect to the center thereof. Dividing means, a second dividing means for further dividing the end area and the middle area substantially in parallel to a direction corresponding to a track, and dividing by the first dividing means and the second dividing means. A light receiving element having a plurality of light receiving cells for receiving the divided light, wherein a tracking error detecting means responds to the outputs of the plurality of light receiving cells for receiving the light in the middle area divided by the second dividing means. The tracking error signal is detected by the calculation
The position detecting means calculates the position of the light beam and the light receiving means in accordance with the relative position of the light beam and the light receiving means in the radial direction of the disk by calculating in accordance with the outputs of the plurality of light receiving cells which receive the light of the end area divided by the second dividing means. The tracking adjustment device according to claim 2, wherein the value is detected.