JP3434230B2 - Optical disk drive - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mini disc (abbreviated as "MD") and a compact disc ("CD").
Abbreviated as "), a magneto-optical disk (abbreviated as" MO "), a phase change disk (abbreviated as" PC "), which is a recording device for recording information on an optical disk, and which reproduces information recorded on the optical disk. The present invention relates to a reproduction apparatus and an optical disk drive apparatus including a recording / reproduction apparatus for recording / reproducing information on / from an optical disk. More specifically, the present invention relates to detection and correction of tracking error in an optical disc drive.

[0002]

2. Description of the Related Art Conventionally, a tracking signal detecting method called a far field method (hereinafter abbreviated as "FF method") or a push-pull method (hereinafter abbreviated as "PP method") is used to detect tracking in an optical disk drive. Widely used. For the sake of simplicity, this tracking signal detection method is referred to as "PP method". The PP method requires a large laser output because the required apparatus has a simple structure and the utilization efficiency of laser light is higher than that of other tracking signal detection methods including the three-beam method. Suitable for use in possible optical disk drives.

However, in the PP method, when the objective lens is displaced in the direction perpendicular to the recording track of the optical disk, there is a problem that an offset corresponding to the displacement amount of the objective lens occurs in the tracking error signal.

Since the optical disk always has an eccentricity about the center of rotation, when the optical disk is rotated, the radial position of the recording track on the disk changes rapidly, and the displacement of the objective lens also changes accordingly. The offset of the above tracking error signal also changes at high speed. It goes without saying that tracking cannot be correctly detected under such a high-speed offset fluctuation. Therefore, in general, in the PP method, in order to eliminate the high-speed offset fluctuation, a traverse mechanism capable of high-speed response in which the objective lens is always positioned at the center of the laser optical axis even if the recording track position changes at high speed. It is necessary and causes cost increase.

[0005] Figure 10, as an example of an improved PP method to reduce the offset of the tracking error signal when displacing the objective lens in the PP method proposed recently, JP-A 9-223 3 21 (1997 The optical disk drive device disclosed in August 26 is shown. The optical disk drive ODP1 includes a turntable 2, a motor 3, an objective lens 4, a tracking actuator 5, a tracking controller 6R, a light receiving cell 9, adders 10 and 11, an optical spot displacement detector 12, and a tracking error detector 1.
3, an amplifier 14, and an offset corrector 15.

In the optical disk drive ODP1, the optical disk 1 is fixed to a turntable 2, and the turntable 2 is rotated by a motor 3 to rotate the optical disk 1. The objective lens 4 focuses the laser beam Lb emitted from an optical pickup (not shown) on the recording surface of the optical disc 1 and the laser beam Lb reflected on the recording surface on the light receiving element 9. . The light receiving element 9 has a light spot O of the focused laser beam Lb.
Various electric signals are output according to s.

The structure of the light receiving surface of the light receiving element 9 generally used in the PP method will be briefly described with reference to FIG. The light receiving element 9 shown in FIG.
Of the six light receiving cells ROa, RI, ROb, LOa by a plurality of dividing lines Lv substantially perpendicular to the direction corresponding to the recording tracks of the optical disc 1 and a dividing line Lp substantially parallel to the direction corresponding to the recording tracks of the optical disc 1. , LI, and LOb
Is divided into The light spot Os is connected to the light-receiving surface divided in this way. As shown in FIG. 6B, the light receiving cells ROa, RI, and ROb in the left column receive the reflected light from the outer peripheral side of the recording track Tr. On the other hand, the light receiving cells LOa, LI, and LOb in the right column receive the reflected light from the inner peripheral side of the recording track Tr.

The light receiving cells ROa and ROb and LOa and LOb respectively receive the light in the end region with respect to the center of the light spot Os. Light receiving cell ROa and light receiving cell RO
Areas AoRa and A of the connected light spot Os on b
oRb is a portion irradiated with the 0th-order diffracted light reflected on the recording surface of the optical disc 1 without being diffracted. Similarly,
Light receiving cell LOa and light receiving cell LOb of light spot Os
The upper areas AoLa and AoLb are portions where only the 0th-order diffracted light reflected without diffracting on the recording surface of the optical disc 1 is received. Therefore, these areas do not interfere with the diffracted light from the recording surface of the optical disc 1. In this sense, these areas AoLa,
AoLb, AoRa, and AoRb are collectively set as the non-interference area A.
Collectively referred to as o.

The light receiving cells RI and LI receive light in the middle area with respect to the center of the light spot Os. Spot O
An area AiR occupied by s on the light receiving cell RI and an area AiL occupied by the light receiving cell LI (indicated by hatching in the drawing)
(Indicated by hatching in the figure) is the 0th-order diffracted light reflected without diffracting on the recording surface of the optical disk 1 and ± 1 diffracted and reflected depending on the shape of the recording track on the recording surface of the optical disk 1. This is a region where the second-order diffracted light overlaps and causes interference. In this sense, the areas AiR and AiL are collectively referred to as the interference area Ai.

As shown in FIG. 10, in the optical disk drive device ODP1, the light receiving cell ROa outputs the first outer peripheral side end area signal SROa in accordance with the light spot Os.
The light receiving cell RI outputs an outer peripheral side middle area signal SRI, and the light receiving cell ROb outputs a second outer peripheral side end area signal SROb. Similarly, the light receiving cell LOa outputs the first inner circumference side end area signal SLOa, and the light receiving cell LI outputs the inner circumference side middle area signal S.
LI is output, and the light receiving cell LOb outputs the second inner peripheral side end region signal SLOb.

The adder 10 receives the first outer peripheral side end region signal SROa output from the light receiving cell ROa and the light receiving cell R.
The second outer peripheral side end region signal SROb which is the output from Ob
And are added to generate the outer peripheral side end region signal SRO. Similarly, the adder 11 adds the first inner circumference side end region signal SLOa which is the output from the light receiving cell LOa and the second inner circumference side end region signal SLOb which is the output from the light receiving cell LOb. , The inner peripheral side end region signal SLO is generated.

The light spot displacement detector 12 subtracts the inner peripheral side end region signal SLO from the outer peripheral side end region signal SRO,
An end region signal SO that is the difference between the end region signals is generated. The end area signal SO represents an offset amount that is a relative displacement of the light spot Os connected on the light receiving element 9 in a substantially vertical direction with respect to the recording track. In this sense, the end area signal SO is referred to as a first offset signal.

The amplifier 14 is a light spot displacement detector 12
The first offset signal SO, which is the output of the above, is amplified by a predetermined coefficient k times to generate the weighted second offset signal SOk.

The tracking error detector 13 subtracts the inner-circumference-side middle-region signal SLI, which is the output from the light-receiving cell LI, from the outer-circumference-side middle-region signal SRI, which is the output from the light-receiving cell RI, to obtain the middle-region signal. The intermediate region signal SI that is the difference is generated. The middle area signal SI includes an offset amount and a tracking error amount, which are displacements of the light receiving element 9 and the light spot Os in a direction substantially perpendicular to the recording track.
In this sense, the middle area signal SI is called an offset tracking error signal.

The offset corrector 15 calculates the second offset signal SOk from the offset tracking error signal SI.
Is subtracted to generate a tracking error signal St that does not include the offset amount.

The tracking controller 6R performs phase compensation, low frequency compensation, etc. on the tracking error signal St to generate a tracking control signal Stc. Based on the tracking control signal Stc, the tracking actuator 5 moves the objective lens 4 in a direction perpendicular to the recording track Tr, that is, the optical disk 1 so that the laser beam Lb follows the recording track Tr (not shown) of the optical disk 1.
In the radial direction of.

The operation of the above-mentioned optical disk drive device ODP1 will be described with reference to FIGS. Figure 7
In addition, the reflected light from the disc 1 is received by the light receiving element 9 shown in FIG.
The relationship between the position of the light spot Os connected above and the displacement of the objective lens 4 is shown. FIG. 7A shows a case where the center of the objective lens 4 coincides with the center of the laser optical axis, that is, the displacement amount is zero. FIG. 7B shows a case where the displacement of the objective lens 4 is displaced from the center of the laser optical axis toward the inner peripheral side of the disc 1. Then, FIG. 7C shows a light spot Os formed on the light receiving element 9 when the displacement of the objective lens 4 deviates from the center of the laser optical axis to the outer peripheral side of the disk 1.

FIG. 8 shows the relationship between the offset tracking error signal SI, the first offset signal SO, the second offset signal SOk, the tracking error signal St, and the displacement of the objective lens 4 observed by the optical disk drive ODP1. Indicates. In the figure, the horizontal axis represents the displacement amount D of the objective lens 4 in the direction perpendicular to the recording track, and the vertical axis represents the amplitude A of each signal.

An offset tracking error signal SI, which is a tracking error signal before offset correction, has a displacement amount D of the objective lens 4 centered on an origin where the displacement amount D is zero.
The signal peak changes in proportion to. The offset component included in the offset tracking error signal SI can be represented by the dotted line Da.

The first offset signal SO, which is the difference between the end regions output from the light spot displacement detector 12, changes around the origin in accordance with the displacement amount D of the objective lens 4. However, since the first offset signal SO is a signal obtained from the non-interference area Ao by only the 0th-order diffracted light, its amplitude is obtained from the interference area Ai where the 0th-order diffracted light and the 1st-order diffracted light interfere with each other. 1 / k of the offset component Da included in the offset tracking error signal SI. It should be noted that k is determined by the introduction of the optical system used in the optical disc driving device ODP1 including the objective lens 4 and the state on the recording track surface of the optical disc 1.
This is a uniquely determined coefficient.

The second offset signal SOk is supplied to the amplifier 1
In step 4, the first offset signal SO is amplified by k times and generated. As a result, the second offset signal SOk is the offset component D included in the offset tracking error signal SI.
It has a size equal to a. With the offset corrector 15,
By subtracting the second offset signal SOk from the offset tracking error signal SI, the tracking error signal St from which the offset component Da has been removed is generated.

When the relative position between the laser beam Lb and the recording track Tr changes, the way of interference between the 0th order light and the 1st order light changes in the interference area Ai of the light receiving element 9, so that the middle area signal SI is As shown in 8, it changes to a sine wave,
A so-called far-field (push-pull) tracking error signal is obtained. The laser beam Lb is 1
When moved by the recording track, the phase difference is 360 °. At this time, since there is no interference between the 0th-order diffracted light and the 1st-order diffracted light in the non-interference area Ao, the far-field tracking error signal is not generated in the end area signal SO.

When the center of the objective lens 4 coincides with the center of the optical axis of the laser, the light spot Os is located at the center of the light receiving element 9, as shown in FIG. 7 (a). for that reason,
From the offset tracking error signal SI, as shown in FIG. 8, a far-field tracking error signal having a sinusoidal waveform centered on the 0 level is obtained. In this case, since the displacement amount is zero, the value of the first offset signal SO which is the end region signal is also zero. When the displacement of the objective lens 4 deviates from the center of the optical axis of the laser, FIG. 7 (b) and FIG. 7 (c)
As shown in, the relative displacement between the light spot Os and the light receiving element 9 is displaced in the direction perpendicular to the recording track. for that reason,
As shown in FIG. 8, the offset tracking error signal SI, which is the difference between the middle region signals, is a signal obtained by adding an offset according to the objective lens position (horizontal axis) to the far field tracking error signal. As a result, the first offset signal SO, which is the difference between the end regions, indicates the offset level corresponding to the displacement of the objective lens 4.

That is, the second offset signal SOk generated by giving the appropriate weighting by the coefficient k to the first offset signal SO by the amplifying means 14 generates the offset tracking error signal S by the offset corrector 15.
When subtracted from I, the tracking error signal S does not always include the offset component Da regardless of the displacement of the objective lens 4.
t can be generated.

Next, with reference to FIG. 11, a conventional optical disk drive device having a tracking offset automatic adjustment function will be described. The optical disk drive OD described above
In P1, the coefficient k used in the amplifier 14 is a constant value mainly determined by the state on the recording track surface of the optical disc 1. Therefore, since the state of the recording track surface is different when the optical disc 1 is different, it is necessary to newly set the coefficient k according to the optical disc 1 at least every time the optical disc 1 is exchanged.

Optical disk drive ODP2 in this example
Then, every time the optical disc 1 is exchanged, an appropriate coefficient k corresponding to the optical disc 1 is automatically obtained once at the beginning. Then, the offset tracking error signal SI is corrected by the first offset signal SO generated based on the obtained coefficient k to obtain the tracking error signal St. That is, by automatically obtaining the optimum coefficient k for each optical disk 1, the tracking offset value when the objective lens 4 is displaced is corrected.

The optical disc drive ODP2 is obtained by replacing the tracking controller 6R of the optical disc drive ODP1 shown in FIG. 10 with an initial offset correction coefficient setter ACS. The initial offset automatic adjuster ACS includes a tracking control switching device 6RR, an offset measuring device 16,
A correction amount calculator 17, a forced lens displacement device 18, and a switch SW are included. The forced lens displacer 18 outputs a lens drive signal Stp that displaces the objective lens 4 by a predetermined amount, that is, moves a predetermined distance in the tracking direction.

The tracking control switch 6RR is the tracking controller 6R in the optical disk drive ODP1.
Similarly to the above, the mode switching that generates the tracking control signal Stc on the basis of the tracking error signal St and also generates the mode switching signal Ss that controls the operation of the switch SW according to the operation mode of the initial offset correction coefficient setting device ACS. It is also a vessel.

The switch SW selectively selects one of the lens drive signal Stp which is the output of the forced lens displacement device 18 and the tracking control signal Stc which is the output of the tracking control switching device 6R based on the mode switching signal Ss. Is a selection switch that supplies the tracking actuator 5 with.

The offset measuring device 16 tracks the offset component Da that cannot be removed from the offset tracking error signal SI in the second offset signal SOk obtained by correcting the first offset signal SO by the amplifier 14 based on the current coefficient k. The residual offset amount Of is measured from the error signal St to generate the offset amount signal Sof. The correction amount calculator 17 determines the offset amount signal Sof
On the basis of the above, the coefficient correction signal Sk for obtaining an appropriate coefficient k for making the value of the residual offset amount Of zero is generated.

Referring to the flowchart shown in FIG. 12,
The operation of the optical disk drive device ODP2 having the above configuration will be described. When the optical disk drive ODP2 is powered on, the initial offset correction operation by the initial offset corrector ACS is started. Step S70
1, the tracking control switch 6RR first
The mode switching signal Ss is generated, and the output port of the forced lens displacement device 18 is connected to the tracking actuator 5 by the switch SW. Then, the process proceeds to the next step S702.

In step S702, the lens driving signal Stp is supplied from the forced lens displacer 18 to the tracking actuator 5. The tracking actuator 5 displaces the objective lens 4 by a predetermined distance based on the lens drive signal Stp. Then, the process proceeds to step S703.

In step S703, the correction amount calculator 17
Generates a correction coefficient signal Sk for setting the correction coefficient k to 1 / Ko based on the offset amount signal Sof output from the offset measuring device 16. Note that Ko is a fixed value determined in consideration of the maximum eccentricity amount and the minimum eccentricity amount of the optical disc 1, and the maximum offset amount allowed by the optical disc drive device ODP2. Then, the process proceeds to step S704.

In step S704, the amplifier 14 corrects the correction coefficient k (1 / Ko) determined in step S703.
The first offset signal SO is corrected based on the above to generate the second offset signal SOk. Offset corrector 1
Reference numeral 5 corrects the offset of the offset tracking error signal SI based on the second offset signal SOk to generate the tracking error signal St. The offset measuring device 16 measures the residual offset amount Of which is still included in the tracking error signal St for a predetermined time, and also calculates the average value Ofm of the residual offset amount Of measured over the predetermined time (hereinafter, the average offset (Referred to as a value), and the offset amount signal Sof is generated.
Then, the process proceeds to step S705.

In step S705, the correction amount calculator 17 determines based on the offset amount signal Sof whether the average offset value Ofm is less than or equal to a predetermined threshold value Oth. This threshold value Oth is equal to the optical disc drive ODP2.
It is a value that is determined in consideration of the maximum offset amount that is allowed in. When the average offset value Ofm is larger than the threshold value Oth corresponding to the predetermined offset amount, NO is determined and the process proceeds to step S706.

In step S706, the correction amount calculator 17
Is a correction coefficient signal S obtained by adding 1 / Ko to the current coefficient k.
generate k. Then, the process returns to step S704, and after repeating the above-described processes, the processes in steps S704 and S705 are repeated until YES is determined in step S705.

On the other hand, if YES in step S705, that is, if the average offset value Ofm is less than or equal to the threshold value Oth, it is determined that the offset component Da in the offset tracking error signal SI is sufficiently removed with the current coefficient k. It Therefore, the current coefficient k = n / Ko
(N is the number of times determined to be NO in step S705 +
The process ends when 1) is set in the amplifier 14.

As described above, the optical disk drive device ODP
In No. 2, it is possible to automatically determine the unique offset correction coefficient k for each optical disk 1 by using the initial offset correction function.

[0039]

However, the optical disk drive device ODP2 having the above-mentioned initial offset correction function.
Also in the above, it is necessary to forcibly displace the lens when determining the initial offset correction coefficient k. for that reason,
When the lens is forcibly displaced, the laser beam Lb
May extend beyond the automatically adjustable area of the optical disc 1. Below, with reference to FIG. 9 showing the areas of the recording surfaces of various optical disks, the problems in the optical disk drive device ODP2 will be specifically explained.

The optical disk 1 is generally composed of a plurality of areas having different physical characteristics. For example, in a read-only disc such as a CD or MD, information signals are stored in intermittent grooves called pits formed on the recording surface of the disc 1.
There are two types of information carried by the information signal: music information and text information. The character information is stored in the lead-in area Li inside the concentric circle of the optical disc 1, and the music information is stored in the recording area Ar outside the lead-in area Li.
Further, outside the recording area Ar, there is a lead-out area Lo in which music information is not recorded.

As shown in FIG. 9A, in the case of the read-only optical disc 1o, it is surrounded by a concentric circle from the center of the optical disc 1 including the pits from the start position of the lead-in area Li to the end position of the lead-out area Lo. The formed donut-shaped area is called a pit area Rp. Also, the optical disc 1
From the center of the pit to the pit area Rp and the pit area Rp
The area on the outer peripheral side has no pit for storing information. These areas are called mirror surface areas Rm. Information is recorded in the program area Ap provided between the lead-in area Li and the lead-out area Lo in the pit area Rp.

As shown in FIG. 9B, when the optical disc 1 is a recording optical disc 1a such as an MD, the TOC information and the recording information are stored in areas having different physical characteristics. That is, since the TOC information is stored in the lead-in area Li of the pit area Rp, like the read-only optical disc 1o, the TOC information cannot be rewritten. On the other hand, the music information is stored in the recordable area Ar. Further, there is a lead-out area Lo outside of which recording information is not written. These areas Ar and Lo are constituted by grooves continuously formed on the recording surface of the disc. This continuous course is called a groove. A donut-shaped region that is on the outer peripheral side of the pit region and includes a groove from the start position of the recordable area to the end position of the lead-out area is called a groove region Rg. Also, M
In the D recording / playback disc, as in the read-only disc, there is a mirror surface area Rm in which no information is stored.

In this way, in a plurality of regions having different physical characteristics, the laser beam L that is the basis for detecting the tracking error.
The characteristic of b also differs for each reflected region. As a result, the value of the correction coefficient k of the tracking error signal also differs from region to region. Therefore, just as the unique offset correction coefficient k is automatically determined for each optical disk 1, it is necessary to determine the unique offset correction coefficient k for each region of the optical disk 1 having different physical characteristics. is there.

However, by displacing the objective lens 4, the light condensed on the optical disk 1 may be deviated from the intended area and moved to areas having different physical characteristics. In particular, in the MD recording / playback disc, the pit area is 1.5 mm, and the displacement range of the objective lens 4 is
For example, about 700 μm is required. In particular, as described above, the optical discs 1 have different eccentricity amounts, and the position of the recording track fluctuates at high speed according to the high-speed rotation of the optical disc 1, so that the displacement of the objective lens 4 is controlled in the target area. Then, a situation occurs in which the laser beam Lb cannot be focused on the same region. In such a case, correct tracking control cannot be performed because offset correction is performed based on the offset correction coefficient k, which is not suitable for the area irradiated with the laser beam Lb.

In order to avoid such a problem, in order to eliminate the high-speed offset fluctuation, a high-speed response in which the center of the laser optical axis is always focused on the center of the recording track even if the recording track position changes at high speed is possible. There is a problem in that it requires a large traverse mechanism or an actuator mechanism of the objective lens, which causes a cost increase.

The present invention has been made in order to solve the above problems, and in the region where the laser beam Lb is irradiated onto the optical disk, it is possible to obtain a unique offset correction coefficient k for each region having different physical characteristics. An object is to provide an optical disk drive.

[0047]

According to a first aspect of the present invention, a light beam is condensed by an objective lens on a recording surface formed of regions having different physical characteristics of an optical disk, and the light beam is reflected from the recording surface. Is an optical disk driving device that receives a light beam as a light spot by a light receiving element and tracks a light beam on a recording track of a recording surface based on the light spot. The objective lens is shifted substantially perpendicularly to the direction corresponding to the recording track. An optical pickup having an objective lens shift means, a tracking error detection means for detecting a relative position between the recording track and the condensed light beam, and generating an offset tracking error signal including an offset amount and a tracking error amount; An optical spot displacement detecting means for detecting the shift amount of the lens and generating an offset signal; The offset of the offset tracking signal is corrected based on the offset signal, the offset correction means for generating a first tracking error signal,
Forced lens displacement means for driving the objective lens shift means to displace the objective lens in a direction substantially perpendicular to the recording track by a first predetermined amount , and tracking error after displacement of the objective lens by the forced lens displacement means so that the offset in the signal is reduced, the offset signal Osamu
With a positive offset correction correcting means, on the basis of the reflected light beam, and an area discrimination means for the light beam to determine the area of the recording surface of the optical disk that has been condensed, the offset complement
The positive correction means determines the area as a result of the forced displacement of the objective lens.
When it is determined by the means that the converging area of the light beam has changed, the forced lens displacement means reverses the objective lens.
It is characterized in that it is displaced in the opposite direction by a second predetermined amount .

As described above, in the first invention, when the light beam irradiates different areas of the recording surface of the optical disc as a result of the forced displacement of the objective lens, the forced displacement is performed.
Offset signal correction coefficient after displacing in the opposite direction
Therefore, calculate the correction coefficient in the target area.
You can

The second aspect of the present invention is that the physical characteristics of optical discs differ from each other.
Objective lens with a light beam on the recording surface consisting of a region
The light beam reflected by the recording surface
Light is received by the light receiving element as a spot, and the optical spot is received.
The optical beam to the recording track on the recording surface based on the
An optical disk drive for racking, objective lens
Shift in a direction substantially perpendicular to the direction corresponding to the recording track.
Optical pickup having objective lens shifting means
The relative position between the recording track and the focused light beam.
Off, including offset amount and tracking error amount
A tracking error that produces a set tracking error signal
The difference detection means and the offset amount by detecting the shift amount of the objective lens
Optical spot displacement detection means for generating a set signal and offset
The offset of the tracking signal to the offset signal
Compensate based on and generate the first tracking error signal
Drive offset correction means and objective lens shift means.
The objective lens is moved in a direction substantially perpendicular to the recording track.
And forcing the lens displacement means for displacing a predetermined amount, forced les
After the objective lens is displaced by the lens displacement means.
Reduce the offset contained in the King error signal
And an offset correction correction means for correcting the offset signal
And based on the reflected light beam, the light beam
Area judgment to determine the area of the recording surface of the condensed optical disc
The offset correction correction means is an objective lens.
As a result of the forced displacement of the light beam, the area discrimination means
If it is determined that the light collection area has changed, the offset
The correction correction means turns off the preset value set in advance.
Modifying the offset signal by multiplying the set signal
Is characterized by.

As described above, in the second invention, the compulsory
When the light beam illuminates different areas due to displacement
Set a predetermined value as the correction coefficient in the target area.
The processing speed can be increased by
It

A third invention is the objective according to the first invention.
As a result of displacing the lens in the outer peripheral direction of the optical disk,
If the focus area of the beam changes, the objective lens
It is characterized in that it is displaced in the inner circumferential direction of the disk.

A fourth invention is the objective according to the first invention.
As a result of displacing the lens in the inner peripheral direction of the optical disc,
If the focus area of the beam changes, the objective lens
It is characterized in that it is displaced in the outer peripheral direction of the disk.

The fifth invention is any one of the first to fourth inventions.
In the above, the area discrimination means is an optical disc on the recording surface of the optical disc.
The area where the beam is focused is an area consisting of intermittent grooves.
It is characterized by determining whether the area is a continuous groove or a continuous groove.
And

The sixth invention is any one of the first to fourth inventions.
In the above, the area discrimination means is an optical disc on the recording surface of the optical disc.
The information signal is recorded in the area where the beam is focused.
There is no mirror surface area or the area where the information signal is recorded
The feature is that it is determined whether there is any.

The seventh invention is any one of the first to fourth inventions.
, The light beam reflected from the recording surface is received.
To the direction corresponding to the recording track
And split the light spot almost vertically to the center of the light spot.
A first dividing means for dividing into a region and the middle region, end regions
And the middle area to the direction corresponding to the recording track.
Second dividing means and first dividing means for substantially parallel division
And a plurality of light receiving cells divided by the second dividing means.
Error detecting means having a light receiving element having a
Receives the light in the middle area split by the second splitting means
By performing calculation according to the output of multiple light receiving cells
The relative position between the recording track and the light beam is detected and the optical spot is detected.
The displacement detecting means is an end divided by the first dividing means.
Calculation according to the output of multiple light receiving cells that receive the light of the area
To detect the relative displacement of the light spot on the light receiving element.
And are characterized.

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail with reference to FIGS. 1, 2, 3, 4, and 5. With reference to FIG. 1, the structure of a PP type optical disc drive device ODDA according to the present embodiment will be described. The optical disk drive ODDA includes a turntable 2, a motor 3, an objective lens 4, a tracking actuator 5, a light receiving cell 9, adders 10 and 11, and a light spot displacement detector 1.
2, tracking error detector 13, amplifier 14, offset corrector 15, and area offset corrector ACSR
including.

In the optical disk drive ODDA, the optical disk 1 is fixed to the turntable 2, and the turntable 2 is rotated by the motor 3 to rotate the optical disk 1. The objective lens 4 focuses the laser beam Lb emitted from an optical pickup (not shown) on the recording surface of the optical disc 1 and the laser beam Lb reflected on the recording surface on the light receiving element 9. . The light receiving element 9 has a light spot O of the focused laser beam Lb.
Various electric signals are output according to s. Light receiving element 9
Is a light receiving element generally used in the PP method, and its structure is as described in detail with reference to FIG.

Therefore, as shown in FIG. 1, in the optical disk drive ODDA, according to the light spot Os,
The light receiving cell ROa outputs the first outer peripheral side end area signal SROa, the light receiving cell RI outputs the outer peripheral side middle area signal SRI, and the light receiving cell ROb outputs the second outer peripheral side end area signal SROb.
Is output. Similarly, the light receiving cell LOa outputs the first inner circumference side end region signal SLOa, the light receiving cell LI outputs the inner circumference side middle region signal SLI, and the light receiving cell LOb outputs the second inner circumference side end region signal SLOb. Is output.

The adder 10 receives the first outer peripheral side end region signal SROa output from the light receiving cell ROa and the light receiving cell R.
The second outer peripheral side end region signal SROb which is the output from Ob
And are added to generate the outer peripheral side end region signal SRO. Similarly, the adder 11 adds the first inner circumference side end region signal SLOa which is the output from the light receiving cell LOa and the second inner circumference side end region signal SLOb which is the output from the light receiving cell LOb. , The inner peripheral side end region signal SLO is generated.

The light spot displacement detector 12 subtracts the inner peripheral side end region signal SLO from the outer peripheral side end region signal SRO,
An end region signal SO that is the difference between the end region signals is generated. The end area signal SO represents an offset amount which is a relative displacement of the light receiving element 9 and the light spot Os in a substantially vertical direction with respect to the recording track. In this sense, the end area signal SO is referred to as a first offset signal.

The amplifier 14 includes the light spot displacement detector 12
The first offset signal SO, which is the output of the above, is amplified by a predetermined coefficient k times to generate the weighted second offset signal SOk.

The tracking error detector 13 subtracts the inner circumference side inner area signal SLI which is the output from the light receiving cell LI from the outer circumference side middle area signal SRI which is the output from the light receiving cell RI to obtain the middle area signal. The intermediate region signal SI that is the difference is generated. The middle area signal SI includes an offset amount and a tracking error amount, which are displacements of the light receiving element 9 and the light spot Os in a direction substantially perpendicular to the recording track.
In this sense, the middle area signal SI is called an offset tracking error signal.

The offset corrector 15 calculates the second offset signal SOk from the offset tracking error signal SI.
Is subtracted to generate a tracking error signal St that does not include the offset amount.

The area offset corrector ACSR includes a tracking controller 6, an offset measuring device 16, a correction amount calculator 17, an outer peripheral lens displacement device 101, and an inner peripheral lens displacement device 10.
2, area discriminator 103, and switches SW1 and S
Including W2. The tracking controller 6 is connected to the offset compensator 15 and performs phase compensation, low-frequency compensation, etc. on the tracking error signal St input from the offset compensator 15 to generate the tracking control signal Stc, and Selection signal Ss1 and second selection signal Ss2
To generate.

The first selection signal Ss1 is the switch SW1.
To drive either the output port of the outer peripheral lens displacer 101 or the output port of the inner peripheral lens displacer 102 to the output port of the switch SW1. Similarly, the second selection signal Ss2 is the switch SW
2 is a drive signal that drives 2 to selectively connect either the output port of the switch SW1 or the output port of the tracking controller 6 to the output port of the switch SW2.

That is, the switch SW1 is connected to the tracking controller 6 to input the first selection signal Ss1.
Based on the above, the outer circumferential lens displacement signal 101 is output from the outer circumferential lens displacement device 101 and the inner circumferential lens displacement device 1
The inner peripheral lens drive signal Sis, which is the output from 02, is selectively supplied to the switch SW2. Then, the switch SW2 is connected to the tracking controller 6 and, based on the input second selection signal Ss2, the switch SW1.
The outer peripheral lens drive signal Sos or the inner peripheral lens drive signal Sis input from the tracking controller 6
Any one of the tracking control signals Stc output from is supplied to the tracking actuator 5.

The area discriminator 103 detects the laser beam Lb.
The area of the optical disc 1 which is irradiated with is determined. For the determination of the irradiation area of the optical disc 1 as described above, for example, the method described in Japanese Patent Application No. 07-171843 "Optical disc device" can be used. In this method, it is determined whether the irradiation area of the laser beam Lb of the optical disk 1 is the pit area Rp, the groove area Rg, or the unrecorded mirror surface area Rm by using the difference between the RF signals. Specifically, the RF signal in the pit area contains a high frequency component, but R in the groove area Rg
The region is determined by performing signal processing focusing on the fact that the F signal does not contain high frequency components.

The tracking actuator 5 outputs the laser beam Lb to the optical disc based on any one of the tracking control signal Stc, the outer peripheral direction lens drive signal Sos, and the inner peripheral direction lens drive signal Sis which are selectively supplied from the switch SW2. The objective lens 4 is moved to the recording track T so as to follow the recording track Tr 1 (not shown).
It is displaced in the direction perpendicular to r, that is, in the radial direction of the optical disc 1. More specifically, the tracking actuator 5 displaces the laser beam Lb in the outer peripheral direction of the optical disc 1 based on the outer peripheral direction lens drive signal Sos, and displaces the laser beam Lb in the optical disc 1 based on the inner peripheral direction lens drive signal Sis. Displace in the circumferential direction.

The offset measuring device 16 tracks the offset component Da that cannot be removed from the offset tracking error signal SI with the second offset signal SOk obtained by correcting the first offset signal SO with the amplifier 14 based on the current coefficient k. The residual offset amount Of is measured from the error signal St to generate the offset amount signal Sof. The correction amount calculator 17 determines the offset amount signal Sof
On the basis of the above, the coefficient correction signal Sk for obtaining an appropriate coefficient k for making the value of the residual offset amount Of zero is generated.

The operation of the optical disk drive ODDA will be described below with reference to the flowchart shown in FIG. In the present specification, an example of area offset correction in the pit area Rp of a recording / reproducing disk of an MD as the optical disk 1 will be described. Pit area R
In order to perform the area offset correction on p, first, by using a known means such as a traverse motor and a pit area detection switch, as an initial state, the laser beam Lb is located in the pit on the inner circumference side of the optical disc (MD) 1. The optical pickup is positioned so as to irradiate the region Rp. Further, for simplification, the lens displacement direction is set to the outer peripheral side and the displacement amount is set to ± 350 μm. In such an initial state, the area offset correction operation by the area offset corrector ACSR is started.

In step S201, the tracking controller 6 outputs the first selection signal Ss1 for instructing the selection of the outer peripheral lens displacement device 101 and the second selection signal Ss2 for instructing the selection of the output port of the switch SW1. Based on these selection signals Ss1 and Ss2, the outer peripheral lens drive signal S output from the outer peripheral lens displacement device 101.
os is supplied to the tracking actuator 5 via the switch SW1 and the switch SW2. result,
After the objective lens 4 is displaced in the outer peripheral direction by a predetermined amount,
The process proceeds to the next step S202. In this example,
In order to correct the area offset in the pit area Rp of the optical disc (MD) 1, the objective lens 4 is displaced to the outer peripheral side in this step. However, it goes without saying that the displacement direction of the objective lens 4 may be either the outer peripheral side or the inner peripheral side depending on the type of the optical disc 1 to be subjected to the region offset correction and the region thereof.

In step S202, the area discriminator 103
Thus, it is determined which of the pit area Rp, the groove area Rg, and the mirror surface area Rm the portion of the optical disc 1 irradiated with the laser beam Lb is. Then, a process progresses to step S203.

In step S203, step S201
As a result of the displacement in the outer peripheral direction, it is determined whether the type of the irradiation area of the optical disc 1 has changed. Then, when the irradiation area is changed to the groove area Rg or the mirror surface area Rm, YES is determined and the process is step S20.
Go to 4. On the other hand, when there is no change in the irradiation area, the process proceeds to step S205.

However, in this example, as described above, the laser beam Lb is initially set so as to irradiate the pit area Rp located on the inner peripheral side of the optical disc (MD) 1. Therefore, the area that can be changed by displacing the objective lens 4 to the outer peripheral side is not the mirror surface area Rm but the groove area Rm as shown in FIG. 9B.
It is g. That is, in this example, when the irradiation area of the optical disc 1 is changed from the pit area Rp to the groove area Rg, the process of step S204 is executed.

In step S204, the switch SW1 generates the first selection signal Ss1 for instructing to select the inner circumferential lens drive signal Sis which is the output of the inner circumferential lens displacer 102. In step S201, since the switch SW2 is still connected to the output of the switch SW1, the inner circumferential lens drive signal Sis is output from the inner circumferential lens displacer 102 to the tracking actuator 5, and the objective lens 4 is moved to the inner circumferential direction. It is displaced by a predetermined amount in the direction. As a result, the laser beam Lb irradiates the pit area Rp of the optical disc 1. Then, the process is step S2.
Go to 05.

In step S205, FIG. 10 and FIG.
The correction coefficient k of the tracking error signal is determined by a method similar to the initial offset correction method implemented by the optical disc drive ODP2 described with reference to FIG.
Then, the process ends.

Here, the length of the pit area in the direction perpendicular to the recording track is 1.5 mm, and the amount of movement of the objective lens 4 in the inner peripheral direction by the area discriminator 103 is 3 mm.
If it is 0.7 mm, which is twice 50 μm, it will be 0.8 mm beyond the pit area and reaching the mirror surface area on the inner side.
I can afford it. Here, even if the eccentricity of the disk is set to 0.2 mm, for example, it does not reach the mirror surface area.

As described above, in the present embodiment, the outer peripheral lens displacement mechanism (6, 101, SW1, SW2) for supplying the drive signal SoS to the tracking actuator 5 in order to displace the objective lens 4 in the outer peripheral direction, An inner peripheral lens displacement mechanism (6, 102, SW1, SW2) for supplying a drive signal Sis to the tracking actuator 5 for displacing the objective lens 4 in the inner peripheral direction, and of the light currently condensed on the optical disc. By including the area discriminator 103 for discriminating the area to which the position belongs, the objective lens 4
Of different physical properties (Rp,
Even when light is focused on (Rg, Rm), the offset correction coefficient k can be appropriately corrected according to the irradiation region by displacing the objective lens 4 in the opposite direction. As a result, it is possible to automatically adjust the tracking offset even in an area having severe physical restrictions such as a pit portion of a recording / playback disk such as an MD.

In the present embodiment, the pit area Rp and the groove area Rg are discriminated by displacing the objective lens 4 on the outer peripheral side. However, the objective lens 4 is displaced and the inner peripheral side of the disc is arranged. Alternatively, the specular area Rm on the outer peripheral side may be determined. here,
The determination as to whether it is the mirror surface area Rm in which the information signal is not recorded or the area (Rp or Rg) in which the information signal is recorded is based on that the RF signal and the tracking error signal are not output in the mirror surface area. Can be easily identified.

With reference to the flow charts shown in FIGS. 3, 4 and 5, a modification of the area offset coefficient correction method described with reference to FIG. 2 in the optical disk drive device ODDA according to the present embodiment will be described. .

In the flowchart shown in FIG. 3, step S204 of the flowchart shown in FIG. 2 is replaced with step S904. That is, step S2
The processing from 01 to step S203 is performed as described above,
In step S203, it is determined that the area has changed, and the process proceeds to step S904.

In step S904, the displacement amount of the objective lens 4 is set smaller than the predetermined displacement amount instructed in step S201. Then, the objective lens 4 is moved to the step S20 by the newly set smaller displacement amount.
It is moved from the initial state position of 1 to the position on the outer peripheral side. Then, the process proceeds to step S205.

In step S205, step S201
The correction coefficient k of the tracking error signal is determined at a position on the inner peripheral side of the position in. Then, the process ends.

In the method shown in the flow chart of FIG.
The area discriminator 103 is used to determine whether or not it has moved to an area having physical characteristics different from those before displacement, and when the area has moved to a different area, the objective lens is displaced to the side opposite to the direction of movement. On the other hand, in this modification, the displacement amount of the objective lens is reduced so as not to move to a different area, and the correction coefficient k of the tracking error signal is obtained.

Further, in the flowchart shown in FIG. 4, step S204 of the flowchart shown in FIG. 2 is replaced with step S1004. That is, the processing from step S201 to step S203 is performed as described above, it is determined in step S203 that there is a change in the area, and the processing proceeds to step S1004.

In step S1004, the optical pickup is moved in a direction substantially perpendicular to the direction corresponding to the recording track of the optical disc 1, and the same area as that irradiated by the laser beam Lb before the displacement in step S201. The position of the objective lens 4 is returned so as to irradiate. Then, the process proceeds to step S205.

As described above, in this modification, when the irradiated portion of the laser beam moves to a region having physical characteristics different from those before the displacement, as in the method shown in FIG. Instead of displacing the objective lens
By moving the optical pickup using an optical pickup moving mechanism that moves the pickup in a direction substantially perpendicular to the direction corresponding to the recording track, the objective lens is returned to the region before displacement to correct the tracking error signal correction coefficient k. Can be asked.

Further, in the flowchart shown in FIG. 5, step S204 of the flowchart shown in FIG.
Has been replaced by step S1104. That is, the processing from step S201 to step S203 is performed as described above, it is determined in step S203 that there is a change in the area, and the processing proceeds to step S1004.

In step S1104, the predetermined value set in advance is set as the correction coefficient k of the tracking error signal, and then the process ends.

As described above, in this modification, when the irradiation portion of the laser beam Lb moves to a region having physical characteristics different from those before displacement, instead of obtaining the correction coefficient k of the tracking error signal, it is set in advance. The predetermined value that has been set is used as the correction coefficient k. As a result, when the relative eccentricity amount between the optical disc 1 and the optical disc drive ODDA is large and it is difficult to obtain the correction coefficient k of the tracking error signal by the method shown in FIGS. 2, 3, and 4. Is an effective solution.

As described above, in the present specification,
Although the case where the optical disc 1 is an MD recording / reproducing disc has been described, it will be apparent to those skilled in the art from the above description that the present invention can be applied to all optical discs having regions with different physical characteristics. Further, although it has been described that the pit area Rp and the groove area Rg are discriminated by displacing the objective lens 4 on the outer peripheral side, the objective lens 4 is displaced on the inner peripheral side and a mirror surface area inside the pit area Rp is formed. It can also be realized by a method of discriminating Rm. Here, the mirror surface area R where the information signal is not recorded
Area Rp or R where information signal is recorded
The determination of g can be easily made based on the fact that no RF signal or tracking error signal is output in the mirror surface region Rm. Further, as described with reference to FIGS. 2, 3, and 4, when it is determined in step S203 that there is a change in the area, step S20 is performed, respectively.
After displacing the objective lens or the light pickup in S4, S904, and S1004, the correction coefficient k is determined in step S205. However, this step S
Instead of the correction coefficient k by 205, the processing of step S1104 described with reference to FIG. 5 may be executed to set a predetermined value to the correction coefficient k.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical disk drive device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation of the optical disk drive device shown in FIG.

3 is a flowchart showing a modified example of the operation of the optical disc drive device shown in FIG.

FIG. 4 is a flowchart showing a different operation of the optical disc drive device shown in FIGS. 2 and 3.

5 is a flowchart showing a further different operation from the operation of the optical disk drive device shown in FIGS. 2, 3 and 4. FIG.

FIG. 6 is an explanatory diagram of a structure of a light receiving surface of a light receiving element generally used in the push-pull method.

7 is an explanatory diagram of a relationship between a position of a light spot formed by reflected light from a disc on the light receiving element shown in FIG. 6 and displacement of an objective lens in the push-pull method.

8 is an explanatory diagram of a relationship between various signals observed in the optical disk drive device shown in FIG. 1 and displacement of an objective lens.

FIG. 9 is an explanatory diagram of an area on a recording surface of various optical disks.

FIG. 10 is a block diagram showing the structure of a conventional optical disk drive device based on an improved PP method that reduces the offset of a tracking error signal when the objective lens is displaced in the PP method.

11 is a diagram in which an automatic determination function of a tracking error correction coefficient is added to the optical disk drive device shown in FIG.
It is a block diagram which shows the structure of the conventional optical disk drive device.

FIG. 12 is a flowchart showing an operation of the optical disk drive device shown in FIG.

[Explanation of symbols]

ODDA Optical disk drive ACSR Area offset corrector 1 Optical disk 2 Turntable 3 Motor 4 Objective lens 5 Tracking actuator 6 Tracking controller 9 Light receiving element 12 Optical spot displacement detector 13 Tracking error detector 14 Amplifier 15 Offset corrector 16 Offset measuring instrument 16 17 Correction amount calculator 101 Outer circumference lens displacer 102 Inner circumference lens displacer 103 Area discriminator SW1, SW2 Switch 7 Light spot 9 Light receiving element ROa, ROb, LOa, LOb Light receiving cell RI for receiving end area of light spot, Light receiving cell Lv for receiving light in the middle region of the LI light spot Dividing line Lp dividing the light receiving element in the vertical direction from the recording track Lp Dividing line dividing the light receiving element in the horizontal direction from the recording track 1o Reproduction-only optical disc 1a Recording optical disc Rp Tsu door area Rg groove region Rm mirror surface area Ap program area Ar recordable area Li lead-in area Lo lead-out area

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G11B ^7/ 08-7/10

Claims (7)

(57) [Claims] 1. A light beam is condensed by an objective lens on a recording surface composed of regions having different physical characteristics of an optical disc, and the light beam reflected from the recording surface is received by a light receiving element as a light spot, and the light beam is received. An optical disk drive device for tracking the light beam on a recording track on the recording surface based on a spot, the optical disk drive device having an objective lens shift means for shifting the objective lens substantially perpendicularly to a direction corresponding to the recording track. A pickup; tracking error detection means for detecting a relative position between the recording track and the condensed light beam to generate an offset tracking error signal including an offset amount and a tracking error amount; and a shift amount of the objective lens. A light spot displacement detection means for detecting and generating an offset signal; An offset correction unit that corrects the offset of the tracking signal based on the offset signal to generate a first tracking error signal; and the objective lens shift unit are driven to drive the objective lens shift unit in a direction substantially perpendicular to the recording track. Objective lens is the first predetermined amount
And forcing the lens displacement means for by a displacement, and the like offset objective lens is included in the tracking error signal after being displaced is reduced, the offset correction modifying means for modifying the offset signal by the forcible lens displacement means, on the basis of the reflected light beam, and a region determination unit that the light beam to determine the area of the recording surface of the optical disk is condensed, forced displacement results of the objective lens, the area discriminating means
If it is determined that the converging area of the light beam has changed, the forced lens displacement means reverses the objective lens.
An optical disk drive device characterized by displacing in a direction by a second predetermined amount . 2. A region having different physical characteristics of an optical disc.
The light beam is focused by the objective lens on the recording surface that consists of areas
The light beam reflected from the recording surface as a light spot
Light is received by the light receiving element, and based on the light spot
Tracking the light beam on a recording track on the recording surface
An optical disc drive apparatus for driving the objective lens in a direction corresponding to the recording track.
And has an objective lens shift means for shifting in a substantially vertical direction.
Optical pickup, relative position between the recording track and the focused light beam
Detected, and includes offset amount and tracking error amount
Tracker for generating offset tracking error signal
Error detecting means and the shift amount of the objective lens to detect the offset signal.
The optical spot displacement detection means to be generated and the offset of the offset tracking signal are
First tracking by correcting based on the facet signal
An offset correction means for generating an error signal and the objective lens shift means are driven to drive the recording track.
The objective lens by a predetermined amount in a direction substantially perpendicular to the
The forced lens displacement means for moving the objective lens and the objective lens displaced by the forced lens displacement means.
Offset included in the tracking error signal after
To correct the offset signal so that
The light beam is focused on the basis of the reflected light beam by the fusing correction and correction means.
Area judgment for discriminating the area of the recorded surface of the optical disc
And another means, and as a result of the forced displacement of the objective lens,
It is determined that the converging area of the light beam has changed.
In this case, the offset correction / correction means is previously set.
By multiplying the offset signal by a predetermined value that has been set,
Optical disc characterized by correcting an offset signal
Drive. 3. The objective lens is displaced in the inner peripheral direction of the optical disc when the condensing area of the light beam is changed as a result of the displacement of the objective lens in the outer peripheral direction of the optical disc. The optical disk drive device according to claim 1. 4. The objective lens is displaced in the outer peripheral direction of the optical disc when the condensing area of the light beam changes as a result of the displacement of the objective lens in the inner peripheral direction of the optical disc. The optical disk drive device according to claim 1. 5. The area discriminating means discriminates whether a portion of the recording surface of the optical disc on which the light beam is condensed is an area formed by an intermittent groove or an area formed by a continuous groove. The optical disk drive device according to any one of claims 1 to 4, characterized in that: 6. The area discriminating means determines that a portion of the recording surface of the optical disc on which the light beam is focused is a mirror surface area in which no information signal is recorded or an area in which an information signal is recorded. The optical disk drive device according to claim 1, wherein it is determined whether or not there is. 7. A light spot obtained by receiving a light beam reflected from the recording surface is divided substantially perpendicular to a direction corresponding to the recording track, and the light spot is divided with respect to the center thereof. First dividing means for dividing into an area and a middle area; second dividing means for further dividing the end area and the middle area substantially parallel to a direction corresponding to the recording track; It has a light receiving element having a plurality of light receiving cells divided by the dividing means and the second dividing means, and the tracking error detecting means receives the light of the middle region divided by the second dividing means. The relative position between the recording track and the light beam is detected by performing an operation according to the outputs of a plurality of light-receiving cells, and the light spot displacement detection means is divided by the first division means. According to any one of claims 1 to 4, characterized in that for detecting the relative displacement of the light spot on the light receiving element using the operation in accordance with the output of the plurality of light receiving cells for receiving light region Optical disk drive.