JPH06282952A - Information recording and reproducing device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an information recording / reproducing technology capable of realizing appropriate tracking control in view of information recording / reproducing operation by reflecting the state of crosstalk in the tracking control. [Structure] A tracking control system is provided with a tracking offset application circuit 19, and a recording / reproduction control system includes an offset optimization processing circuit 40.
6, a D / A converter 22, a D / A converter 39, a data hold circuit 37, and a comparator 38. The logic control system 26 detects the crosstalk amount when the offset amount in the tracking offset applying circuit 19 is intentionally changed through the data hold circuit 37 and the comparator 38, and based on the detection result, selects the optimum offset amount. The tracking control is set in the application circuit 19 to reflect the crosstalk amount (maintain the crosstalk amount to the minimum).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording / reproducing technique, and more particularly to a technique effectively applied to tracking control in an optical disk device or the like.

[0002]

2. Description of the Related Art For example, an optical disk apparatus for recording a large amount of information such as an image or a document by changing the surface condition of the disk by irradiating spot-shaped laser light according to the recorded information has been put into practical use.

By the way, in such an optical disk apparatus, it is necessary to perform tracking control of the laser beam with respect to an information recording area such as a track provided on the disk with high accuracy in order to narrow the interval between adjacent tracks. It is important from the viewpoint of improving the information recording density due to the adoption of the same technology.

Conventionally, with respect to such tracking control, for example, the technique disclosed in Japanese Patent Laid-Open No. 63-37828 is known. That is, the tracking error is detected by detecting the offset amount of the tracking error signal from the peak value data of the tracking error signal and applying a bias for correcting the offset to the detection signal of the objective lens detector by referring to the built-in memory. Is intended to compensate.

[0005]

However, the above-mentioned prior art does not take into consideration the original purpose of tracking control, that is, ensuring the reliability of the recording / reproducing data. Is closed in the tracking control system and does not reflect the actual state of crosstalk between adjacent tracks, for example.

Therefore, for example, when an imbalance occurs in the error detection system of the tracking control system or the like, proper tracking control becomes impossible, and the reliability of data may be impaired.

Further, when trying to maintain the accuracy of the tracking control system by force, the tolerance of the characteristic of the component parts and the assembling accuracy are required to be higher than necessary, and the manufacturing cost of the apparatus is increased. Cause

An object of the present invention is to record information by reflecting the state of crosstalk in tracking control.
Realizing proper tracking control from the perspective of playback operation,
It is to provide an information recording / reproducing technology capable of improving the reliability of information.

Another object of the present invention is to provide an information recording / reproducing technique capable of reducing the manufacturing cost by relaxing the allowable values of the characteristics required for the components of the tracking control system and the assembly accuracy. It is in.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0011]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows.

That is, according to the present invention, a rotating recording medium, a light source for generating a light beam, an optical system for irradiating the light beam in a spot shape on the recording medium, and a track provided on the recording medium by controlling the optical system are provided. The automatic focus control system that focuses the light flux, the tracking control system that controls the optical system to follow the track of the light flux, and the writing of data to the track by changing the intensity of the light flux according to the recording data. Information including a recording / reproducing control system for performing at least one of a recording operation to be performed and a reproducing operation to read recorded data by detecting reflected light, scattered light or transmitted light obtained from a recording medium by irradiation of a light beam. In a recording / reproducing apparatus, an offset amount setting means capable of arbitrarily setting an offset amount of a light flux with respect to a track and an offset amount. The relationship between the offset amount and the crosstalk amount between adjacent tracks is measured by intentionally changing the offset amount of the light flux to the track via the amount setting means, and the offset amount that minimizes the crosstalk amount is determined as the offset amount. Offset setting means for setting the setting means is provided, and a test area used for measuring the relationship between the offset amount and the crosstalk amount between adjacent tracks is arranged on a part of the recording medium.

[0013]

According to the above information recording / reproducing apparatus of the present invention,
On a part of the recording medium, for example, a test area is set so that tracks on which information of a specific pattern is previously recorded are adjacent to each other on both sides of a central track on which no information is recorded. With the light flux positioned, the offset optimization means intentionally changes the light flux in the track width direction via the offset amount setting means,
At this time, the recording / reproducing control system monitors and records the crosstalk amount read from the center track to grasp the relationship between the offset amount and the crosstalk amount. Then, the offset amount with which the crosstalk amount is the minimum or within the appropriate range is found, the offset amount is set in the offset amount setting means, and the normal recording / reproducing operation is executed.

As a result, since the crosstalk measurement result at the time of actual recording / reproducing of data is reflected in the tracking control, malfunctions in the recording / reproducing control system due to the deviation of the tracking control system are surely avoided. Is
A highly reliable information recording / reproducing operation can be realized.

Further, by reflecting the crosstalk measurement result at the time of actual recording / reproducing of data in the tracking control, it is possible to relax the tolerance accuracy of the characteristics of the circuit components constituting the tracking control system and the assembly accuracy. This makes it possible to reduce the manufacturing cost of the information recording / reproducing apparatus.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An information recording / reproducing apparatus according to an embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing an example of the configuration of the information recording / reproducing apparatus of this embodiment, and FIG. 2 and FIG.
(A)-(c) is a conceptual diagram which shows an example of a structure of the recording medium in the information recording / reproducing apparatus of a present Example. 4 and 5 are diagrams showing an example of the operation.

In this embodiment, an optical disk device will be described as an example of the information recording / reproducing device. As illustrated in FIG. 1, an optical disc 1 as a recording medium has an information recording surface 2 and is controlled and rotated by a spindle motor 3 at a constant speed or a variable speed. Information is recorded on the optical disk 1 by a logic control system 11 which issues a laser output control command, a light beam 8a emitted from a semiconductor laser 8 through an optical system 7 via a control circuit 10 and a laser driver 9.
After passing through, the recording surface 2 is focused by the squeezing lens 5, and the recording surface 2 is physically deformed by the light spot 6 (spot) or the physical properties are changed. In addition, reproduction of information from the optical disc 1 is performed by the recording surface 2
The reflected light 8b from is detected by the signal system detector 27.

The light spot 6 of the light beam 8a irradiated on the recording surface 2
Requires a fine dimension of 1 μm or less in diameter, and the light spot 6 is always positioned within a certain range with respect to the center of the track even if fluctuations of the grooves forming the track, which is the information recording area of the recording surface 2, change. As described above, it is necessary to perform high-precision track control in which the groove runout is suppressed to ± 0.1 μm or less and the tracking is performed.

Since the tracking control system of this embodiment causes the light spot 6 to follow the track on the optical disc 1, the track shift is minimized by the track shift detection signal from the tracking system / autofocus light spot detector 12. So that
The track mirror drive signal 45 generated through the preamplifier 14, the differential amplifier 18, the tracking offset application circuit 19, the phase compensation circuit 20, and the track mirror drive circuit 21 is applied to the track mirror actuator 24 as a desired current component, and the track mirror is applied. 25 is driven.

On the other hand, in the autofocus system, the reflected light 8b from the recording surface 2 is separated from the light beam 8a by the optical system 7 through the focusing lens 5, and the recording system 2 is separated by the tracking system / autofocus light spot detector 12. And the focus of the light spot 6 are detected in the optical axis direction, and automatic generation is performed through the preamplifier 13, the differential amplifier 15, the phase compensation circuit 16, and the drive circuit 17 so that the focus shift is minimized. A desired drive current is applied to the automatic focus actuator 4 by the focus actuator drive signal 46 to displace the focusing lens 5 in the optical axis direction, and the focus position of the light spot 6 of the light beam 8a is changed in the optical axis direction of the recording surface 2. Control to follow.

The data detection system uses the reflected light 8 from the recording surface 2.
b is separated from the light beam 8a via the optical system 7, and passed through the signal system detector 27, the preamplifier 28, the differentiating circuit 29, the automatic gain control circuit 30 and the data detecting circuit 31 to thereby perform the signal processing system 3
By performing processing according to 2, the operation of reproducing the target digital information is performed.

In the case of this embodiment, in order to apply an offset to the tracking control system, a signal obtained by digitizing the offset application amount from the logic control system 26 is converted into an analog signal by the D / A converter 22 to generate an offset application amount 23. By setting the tracking offset application circuit 19, an offset is applied to the tracking control system.

In order to detect the influence of crosstalk, the output signal 33 of the differentiating circuit 29 is the bandpass filter 3
4, through the switch 35, and the data hold circuit 37, an envelope waveform is input to one input terminal of the comparator 38. The other input terminal of the comparator 38 is input with the slice level data digitized by the logic control system 26 and converted into analog form via the D / A converter 39. Output 44 of comparator 38
Is fed back to the logic control system 26, and the tracking control system offset data 4 is set as the crosstalk influence amount 43.
1, 42 are processed in the offset optimization processing circuit 40 to set appropriate values.

To take in the data to the data hold circuit 37, the switch 35 provided in the preceding stage is operated by the logic control system 26.
It is performed by opening and closing by the timing control signal 36 from.

Next, the test track and the test area in the optical disc 1 of this embodiment will be described with reference to FIGS.

As illustrated in FIG. 2, a test track 103 for testing the effect of offset on crosstalk in tracking control is adjacent to a track 101 and a track 102 on which pits 104 having a specific pattern are formed in advance. It has been configured.

The test area in which the test track 103 is arranged is, for example, as shown in FIG. 3A, the outer peripheral area 1a or the inner peripheral area of the optical disc 1 other than the user area in which normal data is recorded. Area 1
b in the user area, or a partial radial area 1c in the user area, as illustrated in FIG.
Alternatively, as shown in FIG. 7C, it may be arranged at a sector boundary 1d which is a buffer section between sectors in the user area.

An example of the operation of this embodiment will be described below.

First, the logic control system 26 causes the light spot 6 of the light beam 8a in the test area illustrated in FIG.
Is set and various reproducing amounts are set in the tracking offset applying circuit 19 while performing the reproducing operation on the test track 103, and the crosstalk amount at that time is detected. In this case, since no information is recorded on the test track 103, the adjacent track 101
The information leakage from and 102 can be directly detected as the crosstalk amount.

Then, it is assumed that the measurement result is in the state illustrated in FIG. 4, for example. When there is no offset application according to the amount of crosstalk as in the conventional case, and the relationship shown in the same figure is obtained, the amount of crosstalk is PdB. The amount of crosstalk at this time is equal to or less than the permissible value qdB required to obtain stable data, so there is no problem. However, the margin for the offset of the tracking control system is + a to −b μm as shown in FIG. 1A, the offset in the inner circumferential direction and the offset in the outer circumferential direction are unbalanced, and the margin in the inner circumferential direction is small.

Therefore, in the case of the present embodiment, the logic control system 26 uses the appropriate offset of the tracking control system (see FIG. 4).
In the case of the above example, −c μm) is converted into an analog signal via the D / A converter 22, and the offset application amount 23 is set in the tracking offset application circuit 19 to perform actual data recording / reproducing operation. As a result, the offset margin is a + c to −b + c as shown in (2) of FIG.
μm, the offset margins in the inner and outer circumferential directions can be made substantially equal, and the reliability of the data signal with respect to crosstalk is improved.

Various test timings can be considered for determining the offset amount applied to the tracking control system as described above.

For example, as shown in FIG. 3A, the outer area 1a or the inner area 1b other than the user area.
When the test area is placed in the device, it may be executed as a part of various initialization work of the device, for example, when the device is started up or when the optical disc 1 is replaced, and it is also possible to perform it periodically, that is, continuously. During operation, it may be executed every predetermined time set by a timer or the like, or every predetermined number of operations.

On the other hand, when the test area is arranged in the radial area 1c or the sector boundary 1d as illustrated in FIGS. 3B and 3C, the test area is irradiated with the light beam 8a during normal operation. It can be executed each time point 6 passes. Furthermore, it is also possible to execute it as a part of recovery processing when an error occurs during recording / reproduction.

Next, an example of the operation of this embodiment when the temperature changes will be described.

FIG. 5 is a diagram showing an example of the relationship between the variation of the offset application amount and the crosstalk amount for various temperatures.

Due to the change in temperature, the characteristics of the components such as the optical system 7 change, and the offset of the tracking control system changes. Change in temperature is up to T ₁ ~T ₃ ℃, nominal temperature assumed to be T ₂ ° C.. In the conventional case, the offset margin is a ₂ to -b ₂ µ at the nominal temperature T ₂ ° C.
What was m was a ₁ ~ due to the temperature change of T ₁ ~ T _3.
It becomes -b _{3 and the} margin is reduced.

On the other hand, in the case of the present embodiment, the decrease in the margin due to the temperature change as described above can be grasped by the operation of detecting the crosstalk amount in the test area, and the deviation of the margin can be canceled out. The offset amount is eliminated by setting it in the tracking offset application circuit 19, and it is possible to always maintain the same margin as that at the nominal temperature T ₂ ° C, and to eliminate the imbalance of the margin in the inner peripheral direction and the outer peripheral direction.

Similarly, the inclination of the optical disc 1 which affects the tracking control system, the variation of the characteristics of the tracking system / automatic focus light spot detector 12, the offset of each circuit of the tracking control system, etc. Since it is included in the measurement of the relationship of the crosstalk amount, it is possible to realize the proper application of the offset.

As described above, according to the optical disk device of the present embodiment, the error of the tracking control system itself or the tracking control system due to the fluctuation of the environmental temperature is detected and corrected by the actual measurement of the crosstalk amount. Therefore, the reliability of the data recording / reproducing operation with respect to the optical disc 1 is surely improved.

Further, it is not necessary to make the required characteristics and the assembly accuracy of the circuit elements of the optical system 7 and the tracking control system and the like stricter than necessary, and the manufacturing cost of the device can be reduced.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say.

[0044]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.
It is as follows.

That is, according to the information recording / reproducing apparatus of the present invention, by reflecting the state of the crosstalk in the tracking control, the proper tracking control as seen from the recording / reproducing operation of the information is realized, and the reliability of the information is improved. The effect of being able to improve is obtained.

Further, it is possible to reduce the manufacturing cost by relaxing the allowable values of the characteristics required for the components of the tracking control system and the assembly accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of the configuration of an information recording / reproducing apparatus that is an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing an example of the configuration of the recording medium.

3A to 3C are conceptual diagrams showing an example of the configuration of the recording medium.

FIG. 4 is a diagram showing an example of the operation.

FIG. 5 is a diagram showing an example of the operation.

[Explanation of symbols]

1 Optical Disc (Recording Medium) 1a Outer Area (Test Area) 1b Inner Area (Test Area) 1c Radial Area (Test Area) 1d Sector Boundary (Test Area) 2 Recording Surface 3 Spindle Motor 4 Auto Focus Actuator 5 Focusing Lens 6 Light spot 7 Optical system 8 Semiconductor laser 8a Luminous flux 8b Reflected light 9 Laser driver 10 Control circuit 11 Logic control system 12 Tracking system / auto focus light spot detector 13 Preamplifier 14 Preamplifier 15 Differential amplifier 16 Phase compensation circuit 17 Drive circuit 18 Difference Dynamic amplifier 19 Tracking offset application circuit (offset amount setting means) 20 Phase compensation circuit 21 Track mirror drive circuit 22 D / A converter 23 Offset application amount 24 Track mirror actuator 25 Track mirror 26 Logical control System (offset optimizing means) 27 Signal system detector 28 Preamplifier 29 Differentiator circuit 30 Automatic gain control circuit 31 Data detection circuit 32 Signal processing system 33 Output signal 34 Bandpass filter 35 Switch 36 Timing control signal 37 Data hold circuit 38 Comparator 39 D / A converter 40 Offset optimization processing circuit 41, 42 Tracking control system offset data 43 Crosstalk influence amount 44 Comparator 38 output 45 Track mirror drive signal 46 Autofocus actuator drive signal 101 Track (test area) 102 Track (test Area) 103 Test track (Test area) 104 Pit (Test area)

Claims (1)

[Claims] 1. A rotating recording medium, a light source for generating a light beam, an optical system for irradiating the recording medium with the light beam in a spot shape, and a track provided on the recording medium by controlling the optical system. An automatic focus control system for focusing the light flux, and a tracking control system for controlling the optical system to perform tracking control of the light flux on the track,
A recording operation of writing data to the track by changing the intensity of the light flux according to recording data, and detecting reflected light or scattered light or transmitted light obtained from the recording medium by irradiation of the light flux. An information recording / reproducing apparatus comprising a recording / reproducing control system for performing at least one of reproducing operations for reading the recorded data, comprising an offset amount setting means capable of arbitrarily setting an offset amount of the light flux with respect to the track. ,
By intentionally changing the offset amount of the light flux with respect to the track via the offset amount setting means, the relationship between the offset amount and the crosstalk amount between adjacent tracks is measured to minimize the crosstalk amount. An offset optimization means for setting an offset amount in the offset amount setting means, and a part of the recording medium,
An information recording / reproducing apparatus in which a test area used for measuring the relationship between the offset amount and the crosstalk amount between adjacent tracks is arranged.