JPH1166581A - Optical disc device and tracking correction method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always enable optically scanning of a signal track of an optical disc accurately. SOLUTION: When optically scanning an optical disc 2 with an optical head 7, a tracking error signal obtained is corrected according to an offset voltage previously held to correct the scanning position of the optical head 7 corresponding to the corrected tracking error signal. An offset voltage is detected and held from the tracking error signal at a timing of initialization immediately after the starting of operation, at a standby timing before the optically scanning of the optical head 7, at a timing of restarting after a temporary stoppage of a disc drive mechanism 6, at a timing of the seeking operation of the optical head 7 or at other timings, thereby always enabling optically scanning of the optical disc 2 correctly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk drive for optically scanning tracks by rotating an optical disk, and to a tracking correction method therefor.

[0002]

2. Description of the Related Art Hitherto, an optical disk has been used as a large-capacity information storage medium, for example, a read-only CD-R.
OM (Compact Disc-Read Only Memory), write-once CD-R (CD-Recordable), rewritable MO
(Magnetic Optical Disc) has been put to practical use.

In such an optical disk, signal tracks for storing information are generally formed concentrically or spirally, and information is recorded or reproduced on the signal tracks by an optical disk device such as a CD drive. 2. Description of the Related Art An optical disk apparatus holds and rotates an optical disk by a disk drive mechanism including a turntable and a spindle motor, and optically scans a signal track of the optically driven optical disk with an optical head to record and reproduce information.

At this time, since the signal track of the rotating optical disk fluctuates in the radial direction with respect to the optical head due to a manufacturing error or the like, tracking control for causing the optical head to follow the center line of the signal track is executed. In this tracking control, a tracking error signal corresponding to the position error between the signal track and the optical scanning is generated from the output signal of the optical head that optically scans the signal track of the optical disk, and an actuator or the like corresponding to the tracking error signal generates the tracking error signal. The scanning position of the optical head is corrected on the center line of the signal track.

As a method of generating a tracking error signal, for example, in the case of a three-beam method, an output beam of an optical head is divided into one main beam and two sub-beams by a diffraction grating, and a signal track of an optical disk is separated by the main beam. Optical scanning is performed.

At this time, since the two sub-beams are located on both sides of the signal track to be optically scanned, a tracking error signal is generated as a difference between the detection signals of the two sub-beams reflected on the optical disk. By correcting the scanning position of the optical head so that the tracking error signal becomes “0”, the main beam follows the center line of the signal track.

[0007]

In the above-described optical disk device, the signal track of the optical disk can be accurately optically scanned by correcting the scanning position of the optical head according to the tracking error signal.

However, in practice, an offset voltage is generated in the tracking error signal due to the temperature characteristics of the signal amplifier, and the scanning position of the optical head is displaced from the center line of the signal track. A tracking error may occur during the operation.

In order to prevent this, an offset voltage of the tracking error signal is detected, and the tracking error signal is corrected correspondingly. For example, in an optical disk apparatus disclosed in Japanese Patent Application Laid-Open No. 06-325394, when information reproduction from an optical disk is started, an offset voltage of a tracking error signal is detected and held, and a tracking error signal corresponding to the held offset voltage is detected. Is performed when information is reproduced.

However, in the optical disk device disclosed in the above publication,
Since the detection of the offset voltage is performed only at the time of starting the reproduction of the optical disk, for example, even if the offset voltage of the tracking error signal changes due to the fluctuation of the ambient temperature during the reproduction of the optical disk, this is the time of the next reproduction start. And the tracking error may occur during long-time reproduction.

In the case of an optical disk such as the CD-R or MO described above, writing or erasing of information may be performed on a signal track. In these cases, tracking control is necessary. The optical disk device disclosed in the publication is assumed only at the time of reproducing an optical disk.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an optical disk device in which a tracking error is less likely to occur, and a tracking correction method therefor.

[0013]

According to the present invention, there is provided an optical disk apparatus for rotating an optical disk having signal tracks formed thereon, and optically scanning the signal tracks of the optical disk which is rotated by the disk drive mechanism. An optical head; signal generation means for generating a tracking error signal from an output signal of the optical head; offset detection means for detecting an offset voltage from the tracking error signal generated by the signal generation means; and detection by the offset detection means Offset holding means for holding the set offset voltage, signal correction means for correcting a tracking error signal corresponding to the offset voltage held by the offset holding means, and tracking error signal corrected by the signal correction means. Scanning position of the optical head And it includes a detection control means for detecting an offset voltage, the said offset detecting means and the tracking control means for modifying, and detects the arrival of timing set in advance to.

Therefore, the signal track of the optical disk rotated and driven by the disk drive mechanism is optically scanned by the optical head, and information recording and reproduction are performed on the signal track of the optical disk. At this time, a tracking error signal is generated by the signal generation unit from the output signal of the optical head, and the tracking error signal is corrected by the signal correction unit in accordance with the offset voltage held by the offset holding unit. Since the scanning position of the optical head is corrected by the tracking control means in accordance with the corrected tracking error signal, the optical head optically scans the center line of the signal track of the optical disk.

The detection control means has a predetermined timing set in advance, and when the arrival of this timing is detected, the offset detection means detects the offset voltage and causes the offset holding means to hold the offset voltage. Is executed at an appropriate timing set in advance.

The various means referred to in the present invention may be formed so as to realize their functions. For example, dedicated hardware, a computer provided with appropriate functions by a program, and a computer provided with an appropriate program Permit functions implemented inside, combinations of these, and the like.

The optical disk according to the present invention means an information storage medium having a signal track optically scanned by an optical head. For example, a read-only CD-ROM is used.
ROM, write-once CD-R, rewritable MO, etc. are allowed. The optical disk device is a device that optically scans the optical disk by rotating the optical disk, and performs, for example, a CD-ROM drive for reproducing recorded information on a CD-ROM, and performs at least one of appending and reproducing information on a CD-R CD-R
A drive, an MO drive that performs at least one of recording, reproducing, and erasing of information is allowed in the MO.

In another aspect of the optical disk apparatus as described above, the detection control means sets an initial setting time immediately after activation as a timing for operating the offset detection means. Therefore, the offset voltage of the tracking error signal is detected and held at the time of the initial setting immediately after the startup.

In another aspect of the optical disk apparatus as described above, the detection control means sets a standby time when the optical head does not optically scan the optical disk as a timing for operating the offset detection means. When the optical head is on standby for not optically scanning the optical disk, the offset voltage of the tracking error signal is detected and held.

In another aspect of the optical disk apparatus as described above, the detection control means sets a time point at which the disk drive mechanism is temporarily stopped and then operated again as a timing for operating the offset detection means. . Therefore, the offset voltage of the tracking error signal is detected and held at the time when the disk drive mechanism is temporarily stopped and then operated again.

In another aspect of the optical disk apparatus as described above, the detection control means sets a timing of a seek operation in which the optical head crosses a plurality of tracks of the optical disk as a timing for operating the offset detection means. Have been. Therefore, at the time of the seek operation in which the optical head traverses a plurality of tracks of the optical disk,
The offset voltage of the tracking error signal is detected and held.

According to the tracking correction method of the present invention, a signal track of an optical disk rotationally driven by a disk drive mechanism is optically scanned by an optical head, and a tracking error signal is generated by a signal generating means from an output signal of the optical head. An optical disc for correcting a tracking error signal by a signal correcting means in accordance with the offset voltage held by the offset holding means, and correcting a scanning position of the optical head by a tracking control means in accordance with the corrected tracking error signal; In the tracking correction method of the apparatus, an offset voltage of a tracking error signal is detected when a preset timing comes, and the offset voltage is held by the offset holding means.

Therefore, the signal track of the optical disk which is rotationally driven by the disk drive mechanism is optically scanned by the optical head, and information recording and reproduction are performed on the signal track of the optical disk. At this time, a tracking error signal is generated by the signal generation unit from the output signal of the optical head, and the tracking error signal is corrected by the signal correction unit in accordance with the offset voltage held by the offset holding unit. Since the scanning position of the optical head is corrected by the tracking control means in accordance with the corrected tracking error signal, the optical head optically scans the center line of the signal track of the optical disk.

However, when an appropriate timing set in advance arrives, the offset detecting means detects the offset voltage and causes the offset holding means to hold the offset voltage. Executed at the timing.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a main part of the optical disk device of the present embodiment, and FIG. 2 is a flowchart showing a tracking correction method of the optical disk device.

The optical disk device 1 according to the present embodiment has a structure shown in FIG.
As shown in FIG. 1, a turntable 3 for holding an optical disk 2 is provided. The turntable 3 is rotatably supported by a spindle motor 4. A dedicated drive circuit 5 is connected to the spindle motor 4.
These portions form a disk drive mechanism 6 that drives the optical disk 2 to rotate.

An optical head 7 is disposed at a position facing the surface of the optical disk 2 held by the disk drive mechanism 6, and the optical head 7
1, a beam splitter 12, an objective lens 13, a light receiving element 14, an actuator 15 for tracking, an actuator (not shown) for focusing, and the like.

The laser light source 11 emits a laser beam,
The beam splitter 12 splits the laser beam into an output optical path and a return optical path. The objective lens 13 forms an image of the emitted laser beam on the surface of a signal track (not shown) of the optical disk 2, and the light receiving element 14 photoelectrically converts the laser beam reflected by the optical disk 2. The tracking actuator 15 adjusts the position of the objective lens 13 in the tracking direction, and the focusing actuator adjusts the position of the objective lens 13 in the focusing direction.

The light receiving element 14 of the optical head 7 is connected to a signal generating circuit 22 which is both a signal generating means and a signal correcting means of the tracking adjustment circuit 21, and a servo circuit 23 connected to the signal generating circuit 22. Are connected to a tracking actuator 15 of the optical head 7.

The signal generation circuit 22 outputs E, which is the output signal of the optical head 7, from the addition / subtraction circuit 24 and the filter circuit 25.
A tracking error signal is generated from the signal and the F signal, and the servo circuit 23 controls the operation of the actuator 15 of the optical head 7 so that the tracking error signal becomes "0". Thus, a tracking control means for correcting the scanning position of the optical head 7 is formed.

An output terminal of the signal generation circuit 22 is connected to an offset detection circuit 26 serving as offset detection means. The offset detection circuit 26 is connected to an input terminal of the signal generation circuit 22 by feedback. The offset detection circuit 26 includes a sample / hold circuit 31, an addition / subtraction circuit 32, a low-voltage power supply 33, an average value circuit 34, and the like corresponding to an offset holding unit. The average value circuit 34 includes a peak hold circuit 35, A bottom hold circuit 36, an addition / subtraction circuit 37, a filter circuit 38, and the like are provided.

The average value circuit 34 is a peak hold circuit 3
5, the peak value of the tracking error signal is held, the bottom value of the tracking error signal is held by the bottom hold circuit 36, these hold values are added / subtracted by the addition / subtraction circuit 37, and then the noise component is filtered by the filter circuit 38. An average value of the tracking error signal is generated.

As described above, the difference between the average value of the tracking error signal output from the average value circuit 34 and the reference voltage generated by the constant voltage power supply 33 is calculated by the addition / subtraction circuit 32, and this difference is used as the offset voltage. It is held by the sample hold circuit 31.

A pulse generation circuit 39 is connected to the tracking adjustment circuit 26, and the tracking adjustment circuit 2
6 performs the operation of detecting and holding the offset voltage of the tracking error signal as described above in response to the output pulse of the pulse generation circuit 39.

The optical head 7 is movably supported in the tracking direction by a seek mechanism 42 including a guide rail (not shown) and a linear motor 41. A seek circuit 43 for driving and controlling the linear motor 41 of the seek mechanism 42 is connected thereto.
The seek circuit 43, the drive circuit 5 of the disk drive mechanism 6, the pulse generation circuit 39 of the tracking adjustment circuit 26, and the like are connected to a single microcomputer 44 that integrally controls them.

A main power supply 45 is connected to each part of the microcomputer 44 and the like.
Is connected to a main switch 46. When the main switch 46 is turned on by manual operation,
The power supply from the main body power supply 45 to each unit such as the microcomputer 44 is started, and the optical disc apparatus 1 is started.

The microcomputer 44 is a CPU that executes various types of information processing as a main body of the computer.
(Central Processing Unit), and the CPU has a ROM that fixedly stores various information such as a control program thereof, and a RAM (Random Access Memory) that temporarily stores various information such as processing data of the CPU. Etc. are connected.

The microcomputer 44 is loaded with an appropriate program in advance and executes various types of information processing such as integrated control of each unit in accordance with the program. Therefore, various means are realized by the various functions. I have. As one of such means, the microcomputer 44 includes a detection control means. When the detection control means detects the arrival of a preset timing, the microcomputer 44 causes the offset detection circuit 26 to detect an offset voltage.

More specifically, the microcomputer 4
4 includes timings for operating the offset detection circuit 26, such as the time of initial setting immediately after startup, the time when the optical head 7 does not optically scan the optical disk 2, the time when the disk drive mechanism 6 is temporarily stopped and then restarted, The time of the seek operation in which the optical head 7 traverses a plurality of tracks of the optical disk 2 is set as RO or the like as program setting data.
M and stored in RAM.

When the CPU detects the arrival of the various timings set as described above by the CPU, the microcomputer 44 causes the pulse generation circuit 39 of the tracking adjustment circuit 21 to execute pulse output, and causes the offset detection circuit 26 to output the offset voltage. Perform detection and retention.

In the above-described configuration, the optical disk device 1 according to the present embodiment rotates the optical disk 2 by the disk drive mechanism 6 and optically scans the signal tracks of the optical disk 2 by the optical head 7, for example. The recording and reproduction of information are performed on the signal tracks of the optical disk 2.

At this time, a tracking error signal is generated by the signal generation circuit 22 from the output signal of the optical head 7, and the position of the objective lens 13 is corrected in the tracking direction by the actuator 15 of the optical head 7 in accordance with the tracking error signal. Therefore, the optical head 7 optically scans the center line of the signal track of the optical disk 2. Since the offset voltage of the tracking error signal is held by the sample and hold circuit 31 of the offset detection circuit 26, the signal generation circuit 22 corrects the generated tracking error signal in accordance with the offset voltage, and then corrects the generated tracking error signal to the servo circuit 23. Output.

In the optical disk device 1 of the present embodiment, a tracking error signal is generated from the output signal of the optical head 7 as described above, the offset voltage of the tracking error signal is corrected, and the corrected tracking error signal is Correspondingly, the scanning position of the optical head 7 is corrected on the center line of the signal track of the optical disk 2.

Then, the optical disk device 1 of the present embodiment
Since the offset voltage of the tracking error signal is detected and held at various preset timings, it is possible to always accurately and optically scan the signal tracks of the optical disk 2 and to record information on the optical disk 2. And reproduction can be performed well.

More specifically, in the optical disk device 1 of the present embodiment, when the main switch 46 is manually turned on, power is supplied from the main body power supply 45 to each unit, the entire device is started, and the initial setting is executed. Is done. At this time, the microcomputer 44 causes the pulse generation circuit 39 of the tracking adjustment circuit 26 to output a pulse during the initialization, whereby the offset detection circuit 26 detects and holds the offset voltage of the tracking error signal.

Further, as shown in FIG. 2, when the optical head 7 waits for the optical head 2 not to optically scan the optical disk 2, when the disk drive mechanism 6 is temporarily stopped and then operates again, At the time of a seek operation crossing a plurality of tracks, the offset detection circuit 26 detects an offset voltage from the tracking error signal and holds the offset voltage.

In the optical disk device 1 of the present embodiment, the offset voltage of the tracking error signal is detected and held at various timings set in advance as described above, so that the signal tracks of the optical disk 2 can always be accurately detected. Optical scanning can be performed. In particular, since any timing is set at a time when the optical scanning of the optical disc 2 is not executed, the optical disc apparatus 1 according to the present embodiment can offset the tracking error signal without obstructing recording and reproduction of information on the optical disc 2. The voltage can be updated.

The present invention is not limited to the above-described embodiment, but allows various modifications without departing from the scope of the invention. For example, in the above embodiment, the microcomputer 4
4 illustrates that various means of the optical disc apparatus 1 are realized by the CPU operating according to the control program stored as software in the ROM or the like.
However, it is also possible to form each of these various means as unique hardware, and it is also possible to store a part of the means as software in a ROM or the like and form a part as hardware.

[0049]

Since the present invention is configured as described above, it has the following effects.

An optical disk drive according to the first aspect of the present invention
A disk drive mechanism for rotating and driving an optical disk having signal tracks formed thereon, an optical head for optically scanning the signal tracks of the optical disk rotated and driven by the disk drive mechanism, and generating a tracking error signal from an output signal of the optical head Signal generating means, an offset detecting means for detecting an offset voltage from a tracking error signal generated by the signal generating means, an offset holding means for holding the offset voltage detected by the offset detecting means, and the offset holding means Signal correction means for correcting a tracking error signal in accordance with the offset voltage held by, and tracking control means for correcting the scanning position of the optical head in accordance with the tracking error signal corrected by the signal correction means, A preset And detection control means for causing the offset detection means to detect the offset voltage when the arrival of the timing is detected, thereby detecting and holding the offset voltage of the tracking error signal at an appropriate timing set in advance. Therefore, it is possible to always accurately and optically scan the signal tracks of the optical disk.

According to a second aspect of the present invention, in the optical disk apparatus according to the first aspect, the detection control means sets an initial setting time immediately after the start as a timing for operating the offset detection means. Accordingly, the offset voltage of the tracking error signal can be detected and held at the time of the initial setting immediately after the startup.

The third aspect of the present invention is the first or second aspect.
The optical disc device according to claim 1, wherein the detection control unit includes:
Since the standby time when the optical head does not optically scan the optical disk is set as the timing for operating the offset detection means, the optical head detects the offset voltage of the tracking error signal when the optical head does not optically scan the optical disk. Can be held.

The invention described in claim 4 is the first to third aspects of the present invention.
The optical disc device according to any one of the above, wherein the detection control means is configured to set a time point at which the disc drive mechanism is temporarily stopped and then operated again as a timing for operating the offset detection means. The offset voltage of the tracking error signal can be detected and held when the drive mechanism is temporarily stopped and then operated again.

The invention according to claim 5 provides the invention according to claims 1 to 4
In the optical disk device according to any one of the above, the detection control unit may set a time point of a seek operation in which the optical head traverses a plurality of tracks of the optical disk as a timing for operating the offset detection unit. Accordingly, at the time of the seek operation in which the optical head crosses a plurality of tracks on the optical disk, the offset voltage of the tracking error signal can be detected and held.

According to a sixth aspect of the present invention, there is provided a tracking correction method, wherein a signal track of an optical disk rotated and driven by a disk drive mechanism is optically scanned by an optical head, and a tracking error signal is generated by a signal generating means from an output signal of the optical head. The tracking error signal is generated and corrected by a signal correcting means corresponding to the offset voltage held by the offset holding means, and the scanning position of the optical head is controlled by the tracking control means in accordance with the corrected tracking error signal. In the tracking correction method of the optical disk apparatus, the offset voltage of the tracking error signal is detected when the timing reaches a preset timing, and the offset voltage is held by the offset holding means. timing Can be held by detecting the offset voltage of the tracking error signal, it is possible to always accurately optically scan the signal track of the optical disk.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a main part of an optical disc device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a tracking correction method of the optical disk device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Optical disk apparatus 2 Optical disk 6 Disk drive mechanism 7 Optical head 22 Signal generation circuit corresponding to signal generation means and signal correction means 26 Offset detection circuit corresponding to offset detection means 31 Sample hold circuit corresponding to offset holding means 44 Detection control means Microcomputer equivalent to

Claims (6)

[Claims] 1. A disk drive mechanism for rotating and driving an optical disk on which signal tracks are formed, an optical head for optically scanning signal tracks of the optical disk rotated and driven by the disk drive mechanism, and an output signal of the optical head Signal generation means for generating a tracking error signal; offset detection means for detecting an offset voltage from the tracking error signal generated by the signal generation means; offset holding means for holding the offset voltage detected by the offset detection means Signal correction means for correcting a tracking error signal corresponding to the offset voltage held by the offset holding means; and correcting the scanning position of the optical head according to the tracking error signal corrected by the signal correction means. Tracking control means; And has an optical disk apparatus comprising a, a detection control means for detecting an offset voltage to the offset detection means to detect the arrival of the timing that is set before. 2. The optical disc apparatus according to claim 1, wherein said detection control means sets an initial setting time immediately after startup as a timing for operating said offset detection means. 3. The optical disk device according to claim 1, wherein the detection control unit sets a standby time when the optical head does not optically scan the optical disk as a timing for operating the offset detection unit. 4. The apparatus according to claim 1, wherein the detection control means sets a time point at which the disk drive mechanism is temporarily stopped and then operated again as a timing for operating the offset detection means. Optical disk device. 5. The apparatus according to claim 1, wherein said detection control means sets a time point of a seek operation in which said optical head crosses a plurality of tracks of said optical disk as a timing for operating said offset detection means. An optical disk device according to one of the claims. 6. An optical head optically scans a signal track of an optical disk rotated and driven by a disk drive mechanism, generates a tracking error signal from an output signal of the optical head by signal generation means, and holds the tracking error signal as an offset. In a tracking correction method for an optical disk device, the signal is corrected by a signal correcting means in accordance with the offset voltage held by the means, and the scanning position of the optical head is corrected by a tracking control means in accordance with the corrected tracking error signal. A tracking correction method for detecting an offset voltage of a tracking error signal when a preset timing comes, and causing the offset holding unit to hold the offset voltage.