JPH06139587A - Method and device for recording and reproducing information in optical disk - Google Patents

Abstract

PURPOSE:To stabilize its operation by previously detecting and storing the offset value of a tracking error signal and the relative position of laser beam irradiation at a measuring point in the radial direction of an optical disk before recording and reproducing, and correcting the offset value and the relative position based on storage data at a recording or reproducing time. CONSTITUTION:The offset values of the tracking error signal, the relative position obtained from absolute time information, concretely, the positions corresponding to a distances from a center, at plural positions different from each other in the radial direction of the optical disk are previously stored in a memory in an operation circuit 41 at the time of recording the information in or reproducing the information from the optical disk. Then, the drive stoppage of an objective lens actuator 50 is released, and the contact piece 45c of a switch 45 is connected to a first contact point 45a, and recording and reproducing is performed at the time of recording or reproducing the information. At this time, a correction voltage corresponding to the movement of a laser beam irradiation position is outputted through a D/A converer 44 from the circuit 41, and offset elimination for the entire area of the optical disk is made possible even when the offset is changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk information recording / reproducing method and apparatus for optically recording or reproducing information on an optical disk such as a compact disk (CD).

[0002]

2. Description of the Related Art Conventionally, when recording information on an optical disc or reproducing information from the optical disc, a laser beam is emitted from an optical pickup along a track formed on the optical disc. At this time, it is well known that there are roughly two types of tracking methods for making the irradiation position of the laser beam follow the track, namely, the three-beam method and the one-beam push-pull method.

In the three-beam method, as shown in FIG. 2, a main beam spot S0 for recording information on the track TR or for reading information recorded on the track TR.
And an optical pickup that emits sub-beam spots S1 and S2 located before and after the main beam spot S0. At this time, each of the sub-beam spots S1 and S2 is located on the left and right of the track TR, and when the main beam spot S0 is located right above the track TR, both the sub-beam spots S1 and S2 slightly hit the track TR. ing. In such a state, the main beam spot S0 can be always positioned on the track TR by correcting the irradiation position of the laser beam based on the tracking error signal which is the difference in the amount of reflected light from the sub beam spots S1 and S2. Yes, accurate tracking can be performed.

On the other hand, in the one-beam push-pull method, as shown in FIG. 3, a photodetector PD which divides the light amount distribution of the reflected light diffracted by the pits or tracks of the optical disc 1 into two parts is used.
The laser spot can be always positioned on the track TR by correcting the irradiation position of the laser light based on the tracking error signal formed by the difference in the amount of reflected light from the left and right of the track TR, and accurate tracking can be performed. It can be carried out. The 1-beam push-pull method
It can be realized with a very simple structure as compared with the three-beam method.

[0005]

As described above, the one-beam push-pull method can be realized with a very simple structure.
Although the cost can be significantly reduced as compared with the beam method, there is a drawback that tracking offset is likely to occur. That is, when the optical axis such as the objective lens of the optical pickup is slightly moved due to the influence of ambient temperature or the optical axis is tilted and the optical axis is displaced, the spot on the photodetector is also moved and the push-pull signal is offset. Will end up. Further, since the track eccentricity is followed, even when the objective lens moves in the track direction, spot movement occurs and an offset occurs.

If such tracking offsets occur frequently, the operation of the information recording / reproducing apparatus becomes unstable, or malfunction occurs. Specifically, it causes a track search error, a search flow, a thread flow, deterioration of the information recording state, occurrence of an unnecessary track jump, an increase in jitter in a reproduction signal, and the like.

In view of the above problems, it is an object of the present invention to provide an optical disk information recording method and an apparatus therefor capable of greatly reducing the tracking offset particularly when the one-beam push-pull method is used.

[0008]

In order to achieve the above object, the present invention according to claim 1 moves an irradiation position of a laser beam emitted from an optical pickup based on a tracking error signal to move the laser beam to the optical disc. In an information recording / reproducing method for an optical disc, in which information is recorded or reproduced by irradiating the optical disc with a laser beam along a preformed track, the information is recorded or reproduced from the optical disc. Before performing, the offset value of the tracking error signal at at least one measurement point different in the radial direction of the optical disc or a value corresponding to the offset value and the optical disc at the laser light irradiation position on the optical disc at this time The relative position in the radial direction is detected and stored, and When recording information on the disc or reproducing information from the optical disc, an arbitrary radial direction on the optical disc is determined based on the offset value at the measurement point or a value corresponding to the offset value and the relative position. An information recording / reproducing method for an optical disc is proposed in which the tracking error signal is corrected based on a correction value for the offset value calculated corresponding to the relative position.

According to a second aspect of the present invention, the irradiation position of the laser light emitted from the optical pickup is moved based on the tracking error signal, and the optical pickup moves from the optical pickup along a track previously formed on the optical disc. In an information recording / reproducing apparatus for an optical disc which irradiates a laser beam on the optical disc to record or reproduce information, relative position detecting means for detecting a relative position of the laser beam irradiation position with respect to the optical disc in the radial direction of the optical disc, and an optical disc of the optical disc. Storage means for storing the offset value of the tracking error signal or a value corresponding to the offset value and the relative position at at least one measurement point different in the radial direction, and the offset value at the measurement point stored in the storage means Or the value corresponding to the offset value and An arithmetic unit that calculates a correction value for the offset value at an arbitrary relative position in the radial direction of the optical disc based on the relative position, and an offset value of the tracking error signal is corrected based on the calculation result of the arithmetic unit. An information recording / reproducing apparatus for an optical disc is proposed, which is provided with a correction means for performing the correction, and an irradiation position correction means for correcting the irradiation position of the laser beam on the optical disk based on the tracking error signal corrected by the correction means.

[0010]

According to the first aspect of the present invention, the tracking error signal at at least one measurement point different in the radial direction of the optical disc is recorded before the information is recorded on the optical disc or the information is reproduced from the optical disc. The offset value or a value corresponding to the offset value and the relative position of the laser beam irradiation position with respect to the optical disc at this time in the radial direction of the optical disc are detected and stored. In addition, based on the offset value or the value corresponding to the offset value and the relative position at the stored measurement point, before or during recording of information on the optical disc or reproduction of information from the optical disc. A correction value for the offset value is calculated corresponding to an arbitrary relative position in the radial direction on the optical disc. Further, when the information is recorded on the optical disc or the information is reproduced from the optical disc, the offset value of the tracking error signal is corrected based on the calculated correction value, and the offset value of the tracking error signal is corrected from the optical pickup along the track. The optical disk is irradiated with laser light to record or reproduce information.

According to the second aspect, the relative position detecting means detects the relative position of the laser beam irradiation position with respect to the optical disc in the radial direction of the optical disc. Before recording / reproducing information, the offset value of the tracking error signal at at least one different measurement point in the radial direction of the optical disc, the value corresponding to the offset value, and the relative position are stored in the storage means. It Furthermore, based on the offset value or the value corresponding to the offset value and the relative position at the measurement point stored in the storage means by the calculating means,
A correction value for the offset value at an arbitrary relative position in the radial direction of the optical disk is calculated, and the offset value of the tracking error signal is corrected by the correction means based on the calculation result, and the corrected tracking error Based on the signal, the irradiation position correction means corrects the irradiation position of the laser light on the optical disc. As a result, the optical pickup irradiates the optical disc with laser light along the track to record or reproduce information.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing a main part of an information recording / reproducing apparatus for an optical disc according to an embodiment of the present invention, that is, a part relating to tracking control. In the figure, 10 is an optical pickup using the one-beam push-pull method, 20 is a tracking error detection unit, 30 is a reference offset correction unit, 4
Reference numeral 0 is a tracking error correction unit, 50 is an objective lens actuator, and 60 is a slide feed mechanism drive unit.

The optical pickup 10 is provided with a well-known four-divided photodetector 11, and tracking correction is performed by using the total received light amount of the detectors 11a and 11d located on the left side of the track and the total received light amount of the detectors 11b and 11c located on the right side of the track. , And the total amount of light received by the detectors 11a and 11c located on the diagonal line and the detectors 11b and 1c.
Focus correction can be performed by the astigmatism method or the like using the total received light amount of 1d.

Further, as shown in FIG. 4, the optical pickup 10 can be moved in the radial direction of the optical disc 1 by, for example, a well-known slide feed mechanism of a linear motor type. That is, the optical pickup 10 is fixed to the moving body 13 supported by the two parallel shafts 12a and 12b extending in the radial direction of the optical disc 1. The moving body 13 is provided with a drive coil 14, and the sliding mechanism drive unit 60 moves the moving body 13 by an electromagnetic force generated between the drive coil 14 and the magnet 15 when the drive coil 14 is energized.

Further, the optical pickup 10 is provided with an objective lens actuator 50 so that the position of the objective lens 51 can be moved left and right with respect to the track. That is, as shown in FIG. 5, the objective lens 51 has the swing rod 5
2 is fixed to one end of the swing rod 52, and the LED 53 is fixed to the other end of the swing rod 52.
4 are provided. The swing rod 52 is rotated by an electromagnetic force generated by a drive coil and a magnet (not shown).
It is possible to rotate around. Further, rubber dampers 55 are provided on the left and right of the objective lens 51,
Usually, the objective lens 51 is supported so as to be located at the neutral point. Furthermore, in the state where the objective lens 51 is located at the neutral point, two-divided photodetectors 56a and 56b are arranged so as to face the light emitting surface of the LED 53, and the position of the objective lens 51 can be detected by the amount of light received by the photodetectors 56a and 56b. It has become.

The tracking error detector 20 comprises summing amplifiers 21a and 21b, a triangular wave generator 22, an adder 23, a comparator 24, an electronic switch 25, a low pass filter 26 and a subtractor 27. The adder 21a inputs the voltages output from the photodetectors 11a and 11d of the optical pickup 10 and outputs a voltage V1 obtained by adding these, and the adder 21b inputs the voltages output from the photodetectors 11b and 11c of the optical pickup 10. A voltage V2 obtained by adding these is output.

The voltage V1 output from the summing amplifier 21a
Is a gain variable circuit composed of a triangular wave generator 22, an adder 23, a comparator 24, an electronic switch 25, and a low-pass filter 26.
Based on the offset correction voltage Vof output from 0, the voltage value is changed to a predetermined value to be the voltage V3, and then input to the subtractor 27. That is, the voltage V1 is applied to the electronic switch 25.
Is input to the first contact 25a. Further, the second contact 25b of the electronic switch 25 is grounded, and the contact piece 25c is connected to the input terminal of the low pass filter 26. The electronic switch 25 is switched by the control voltage Vse output from the comparator 24, and the contact piece 25c is connected to the first contact 25a when the control voltage Vse is at a high level.
At the low level, the contact piece 25c is connected to the second contact 25b.

On the other hand, the offset correction voltage Vof output from the tracking error correction unit 40 is added to the triangular wave voltage V4 output from the triangular wave generator 22 by the adder 23, and is added as a voltage V5 to the non-inverting input terminal of the comparator 24. Entered in. The voltage V5 is compared with a predetermined threshold voltage Vth by the comparator 24, and the control voltage Vse output from the comparator 24 becomes a high level when the voltage V5 is higher than the threshold voltage Vth, and the voltage V5 is reduced. Threshold voltage Vth
It goes low when: Here, the frequency of the triangular wave voltage V4 output from the triangular wave generator 22 is the voltage V
It is set to 10 times or more of the signal frequency included in 1. As a result, the pulse width of the control voltage Vse is changed corresponding to the level of the offset correction voltage Vof, the electronic switch 25 is switched corresponding to this, and the voltage V1 input to the low pass filter 26 is intermittently the voltage V1. It becomes a thing. When the high-frequency component of the voltage V6 is removed by the low-pass filter 26, the output voltage V3 is smoothed and its level changes according to the pulse width of the control voltage Vse. Further, the subtractor 27 inputs the voltage V3 and the voltage V2, and outputs the voltage of the difference between the voltage V3 and the voltage V2 as the tracking error signal TE.

The reference offset correction section 30 includes an offset detection circuit 31, an offset addition circuit 32, and an adder 3.
3, the offset detection circuit 31 detects the DC component of the tracking error signal TE and outputs its voltage V6. Further, the offset adding circuit 32 inputs the voltage V6, changes the DC voltage VDC so that the voltage V6 becomes 0V, and outputs the DC voltage VDC. This DC voltage VDC is added to the adder 33.
The voltage V output from the offset detection circuit 31 by
6 is added and output as a voltage V7.

The tracking error correction unit 40 includes an arithmetic circuit 41 composed of a CPU and a memory, and an absolute time detection circuit 4.
2, an A / D converter 43, a D / A converter 44 and a switch 45. The arithmetic circuit 41 inputs the value of the voltage V7 output from the reference offset correction section 30 as digital data DA1 via the A / D converter 43, and also inputs the absolute time information detected by the absolute time detection circuit 42. However, the correction voltage Vo of the level calculated based on these information and the preset program
Output f '.

The switch 45 can output either the output voltage Vof 'of the D / A converter 44 or the output voltage V7 of the reference offset correction unit 30 to the tracking error detection unit 20 as the offset correction voltage Vof. It has become. That is, the first contact 45 of the switch 45
The output terminal of the D / A converter 44 is connected to a, the output terminal of the adder 33 is connected to the second contact 45b, and the contact piece 45c is one of the adders 23 of the tracking error detector 20. Is connected to the input terminal of.

The absolute time detection circuit 42 is a summing amplifier 21.
The voltages V1 and V2 output from a and 21b are input, and the absolute time of the laser light irradiation position on the track 2 of the optical disc 1 is detected from the signal components included in these voltages,
This is output to the arithmetic circuit 41 as digital data.

On the optical disc 1 used here, as shown in FIG. 6, a track TR, which is undulated in advance with a slight amplitude, is spirally formed in the recording area. The swell of this track TR is ATIP (Absolute Time In P
It represents absolute time information called regroove data, and has 22.05 KHz as the basic frequency and its frequency is ATI.
Content of bit for each length corresponding to 1 bit of P data (7 cycles of frequency 44.1KHz), that is, this bit is "1"
FSK (Frequency Shift Keying) modulation is performed so as to change ± 1 KHz depending on whether it is 0 or 0.
Therefore, by reproducing this ATIP data, the absolute time, that is, the position on the optical disc 1 can be known.

The objective lens actuator 50 and the slide mechanism drive unit 60 each have an objective lens 51 or an optical pickup 1 based on the tracking error signal TE.
The position of 0 is moved to change the irradiation position of the laser beam on the optical disc 10.

Next, the operation of this embodiment having the above-mentioned structure will be described. When information is recorded on the optical disc 1 or when the information recorded on the optical disc 1 is reproduced by the information recording / reproducing apparatus of the present embodiment, the tracking error signals TE at a plurality of different positions in advance in the radial direction of the optical disc 1 are recorded. A value corresponding to the relative position in the radial direction with respect to the optical disc 1 obtained from the offset and the absolute time information, specifically, the value corresponding to the distance from the center is stored in the memory of the arithmetic circuit 41.

At this time, first, the objective lens actuator 5
0 driving is stopped to hold the objective lens 51 at the neutral point, and the contact piece 45c of the switch 45 is connected to the second contact 45b.
Connect to. As a result, the value of the output voltage VDC of the offset adding circuit 32 is controlled so that the offset voltage V6 in the tracking error signal TE is as small as possible, that is, 0V, and correspondingly is input to the tracking error detection unit 20. The value of the offset correction voltage Vof is changed, and the voltage V3 in which the level of the voltage V1 is changed correspondingly is obtained. Since the voltage V2 is subtracted from the voltage V3 to generate the tracking error signal TE, the offset in the tracking error signal TE is reduced or eliminated.

In this state, the voltage V at the first position P1
The value of 7 and the relative position are stored in memory. Further, the value of the output voltage VDC of the offset adding circuit 32 is adjusted at the second position by changing the position in the radial direction of the optical disc 1,
The offset in the tracking error signal TE is set to 0, and the value of the voltage V7 at the second position P2 and the relative position are stored in the memory. When such a measurement is performed at, for example, five positions P1 to P5 (at least two different points), the value of the voltage V7 at each position (in other words, the value corresponding to the offset generated in the tracking error signal TE is shown. ) May be different. The cause is classified into the optical pickup 10 and the optical disc 1. For example, optical pickup 1
The cause of 0 is a displacement of the optical axis due to a displacement of the objective lens 51 due to a change in ambient temperature.
The causes of 1) include warpage of the optical disc 1, a change in the shape of the groove forming the track 2, and a change in the thickness of the information recording layer in the optical disc 1.

As described above, when the value of the voltage V7 and the relative position are stored in the memory at a plurality of positions and then the information is recorded or reproduced, the driving stop of the objective lens actuator 50 is released, and Information is recorded or reproduced after connecting the contact piece 45c of the switch 45 to the first contact 45a. At this time, the arithmetic circuit 41 outputs, via the D / A converter 44, the correction voltage Vof ′ corresponding to the moving position of the laser light irradiation position with respect to the optical disc 1.

The value of the correction voltage Vof 'is calculated based on the value of the voltage V7 at the plurality of positions P1 to P5 stored previously and the relative position. For example, at an arbitrary position between two positions P1 to P5 that are adjacent to each other in the radial direction of the optical disc 1, the value of the voltage V7 is expressed by a linear equation as if it changes linearly, and the value of the voltage V7 is calculated. The correction voltage Vof 'having this voltage value is output. Further, in the outermost circumference and the innermost circumference, the value of the voltage V7 is similarly expressed by a linear expression, assuming that the voltage V7 changes at the rate of change between the two positions closest to the radial direction. The correction voltage Vof ′ having the value of is output.

Due to the above-mentioned causes,
Even if the offset in the tracking error signal TE changes due to the difference in the position of the optical disc 1 in the radial direction, the offset in the tracking error signal TE can always be removed over the entire area of the optical disc 1. Therefore, the operation as the information recording / reproducing apparatus is not unstable or malfunction is not caused, and the track search error, the search flow, the thread flow, the deterioration of the information recording state, the occurrence of unnecessary track jumps, Alternatively, it is possible to prevent an increase in jitter in the reproduced signal. Further, since it can be configured by a simple circuit, it can be realized at low cost and the device can be downsized.

Further, since the time required for the measurement before the recording / reproducing of the information is very short, it is possible to perform it every time the recording / reproducing of the information is interrupted. The function and reliability of the device can be significantly improved by applying the present invention.

The configuration in this embodiment is an example,
It is not limited to this. For example, in this embodiment, the relative position of the optical disc 1 in the radial direction is obtained from the absolute time, but a position sensor or the like may be used.

Needless to say, the present invention can be applied to a device using an optical pickup having a fixed objective lens, and the same effect can be obtained.

Further, although the number of data to be detected before recording / reproducing information is set to five, the number of data is not limited to this, and it is desirable to appropriately set the data according to the device.

[0035]

As described above, according to the first aspect of the present invention, the offset value or the offset value of the tracking error signal at at least one measurement point which is different in the radial direction of the optical disk before the recording / reproducing of information is performed. Corresponding values and the relative position of the laser light irradiation position with respect to the optical disc in the radial direction of the optical disc at this time are detected and stored, and when recording information on the optical disc or reproducing information from the optical disc. Since the offset value of the tracking error signal is corrected based on the correction value calculated based on the stored data, the objective lens of the optical pickup may slightly move due to the influence of the ambient temperature or the optical disc may tilt. The optical axis may be misaligned, and it may be Even when the offset is changed in Kkingu error signal, it is possible to eliminate the offset in the tracking error signal always over the entire area of the optical disc. Therefore, the operation as the information recording / reproducing apparatus is not unstable or malfunction is not caused, and the track search error, the search flow, the thread flow, the deterioration of the information recording state, the occurrence of unnecessary track jumps, Alternatively, it is possible to prevent an increase in jitter in the reproduced signal.

According to the second aspect, the data stored in advance in the storage means, that is, the offset value of the tracking error signal at at least one measurement point different in the radial direction of the optical disc or the value corresponding to the offset value, and the offset value. A correction value for the offset value of the tracking error signal is calculated by the calculating means based on the relative position of the laser light irradiation position with respect to the optical disc in the radial direction of the optical disc, and information is recorded on the optical disc or the optical disc. Since the offset value of the tracking error signal is corrected based on the correction value when the information is reproduced from, the objective lens of the optical pickup may slightly move due to the influence of the ambient temperature or the optical disc may tilt. And the optical axis shifts,
Even when the offset in the tracking error signal changes due to the difference in the radial position of the optical disc, the offset in the tracking error signal can be removed over the entire area of the optical disc. Therefore, the operation as the information recording / reproducing apparatus is not unstable or malfunction is not caused, and the track search error, the search flow, the thread flow, the deterioration of the information recording state, the occurrence of unnecessary track jumps, Alternatively, it is possible to prevent an increase in jitter in the reproduced signal. Further, since it can be configured by a simple circuit, it has a very excellent effect that it can be realized at low cost and the size of the device can be reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a main part of an information recording / reproducing apparatus for an optical disc according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a three-beam method in tracking.

FIG. 3 is a diagram illustrating a one-beam push-pull method in tracking.

FIG. 4 is a configuration diagram showing a slide feed mechanism of an optical pickup according to an embodiment.

FIG. 5 is a configuration diagram showing an objective lens actuator of an optical pickup according to an embodiment.

FIG. 6 is a diagram illustrating a track formation state of an optical disc used in an example.

FIG. 7 is a diagram showing an example of measurement data in one example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Track, 10 ... Optical pickup, 11 ... Photo detector, 20 ... Tracking error detection part, 21a, 21b ... Summing amplifier, 22 ... Triangular wave generator, 23 ... Adder, 24 ... Comparator, 25 ... Electronic Switch, 26 ... Low-pass filter, 27 ... Subtractor, 30 ... Reference offset correction unit, 31 ... Offset detection circuit, 32
... offset addition circuit, 33 ... adder, 40 ... tracking error correction unit, 41 ... arithmetic circuit, 42 ... absolute time detection circuit, 43 ... A / D converter, 44 ... D / A converter, 45
... switch, 50 ... objective lens actuator, 51 ...
Objective lens, 52 ... Oscillating rod, 53 ... LED, 54 ... Rotating shaft, 55 ... Rubber damper, 56a, 56b ... Photodetector, 60 ... Slide feed mechanism drive section.

Claims (2)

[Claims] 1. An irradiation position of laser light emitted from an optical pickup is moved based on a tracking error signal, and laser light is emitted from the optical pickup to the optical disc along a track previously formed on the optical disc. Then, in the information recording / reproducing method of the optical disc for recording or reproducing the information, before recording the information on the optical disc or reproducing the information from the optical disc, at least one measurement point different in the radial direction of the optical disc is used. The offset value of the tracking error signal or a value corresponding to the offset value and the relative position of the laser light irradiation position with respect to the optical disc at this time in the radial direction of the optical disc are detected and stored, and information is recorded on the optical disc or Playback of information from the optical disc In this case, a correction value for the offset value calculated corresponding to the relative position in the radial direction on the optical disk based on the offset value or the value corresponding to the offset value and the relative position at the measurement point is used. An optical disc information recording / reproducing method, characterized in that the tracking error signal is corrected based on the above. 2. The irradiation position of the laser light emitted from the optical pickup is moved based on the tracking error signal, and the optical pickup irradiates the laser light onto the optical disc along a track previously formed on the optical disc. In an optical disc information recording / reproducing apparatus for recording or reproducing information, relative position detecting means for detecting a relative position of the laser light irradiation position with respect to the optical disc in the radial direction of the optical disc, and at least different in the radial direction of the optical disc. 1
Storage means for storing the offset value of the tracking error signal at a measurement point of a point or a value corresponding to the offset value and the relative position, and the offset value or the offset value at the measurement point stored in the storage means Calculating means for calculating a correction value for the offset value at an arbitrary relative position in the radial direction of the optical disc based on the value and the relative position; and an offset value of the tracking error signal based on the calculation result of the calculating means. And a correction unit for correcting the irradiation position of the laser beam on the optical disc based on the tracking error signal corrected by the correction unit. apparatus.