JP2002183991A - Disk player - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize suitable tracking control in accordance with disk characteristics to be reproduced by switching over a tracking method between a push-pull system and a DPD system. SOLUTION: For a disk player having tracking error generating circuits of the push-pull system and the DPD system, more stable tracking servo characteristics are obtained by detecting the characteristics of the tracking error signals generated by respective circuits and freely selecting the tracking error generating system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc reproducing apparatus, and more particularly, to a disc reproducing apparatus,
The present invention relates to a disk reproducing apparatus having a function of performing tracking servo in an optimum method by switching between a Push Pull tracking method and a DPD tracking method.

[0002]

2. Description of the Related Art When reproducing an optical disk, for example, a CD (Compact Disc, hereinafter referred to as a CD disk for clarity), a three-spot system, a Push Pull system, and a DPD (Differential). Phase
(Detection) type tracking method. Generally, a three-spot method is used for a disk reproducing apparatus for a CD disk, and a DPD method is used for a disk reproducing apparatus for a DVD disk. A disk reproducing apparatus that can reproduce both a CD disk and a DVD disk uses both tracking methods. Tracking control is often used.

When a three-spot tracking control is performed in a disc reproducing apparatus having a recording function for a CD-R disc or a CD-RW disc, a leading spot and a trailing spot are formed between a recorded area and an unrecorded area during a recording operation. As a result, an unbalance of the return light with respect to the preceding spot and the following spot occurs, and an accurate tracking operation cannot be performed. Therefore, the three spot method cannot be used. Therefore,
In a disk reproducing apparatus having a recording function for these disks, tracking control is generally performed by a Push Pull method. CD-R disc and CD-R
In a disk reproducing apparatus having a recording function of a W disk and capable of reproducing both a CD disk and a DVD disk,
Playback of CD disk, CD-R disk and CD-R
In the case of W disc recording, tracking is performed by the Push Pull method, and in the case of DVD disc reproduction, DP is tracked.
Tracking is performed by the D method. However, a CD-ROM disc, a recorded CD-R disc and a CD-RW
In a disk having a pit portion, such as a disk, tracking can be performed by the DPD method used in the case of reproducing a DVD disk. In the case of a device such as a conventional CD-R disc recording device which cannot reproduce a DVD disk, tracking control is performed only by the Push Pull method. However, a device capable of reproducing both a CD disk and a DVD disk is a DVD disk reproduction device. D sometimes used
The tracking of the PD method can be used for a CD disk. Therefore, when playing a CD disc, Push Pull
If a means for switching between the 1-system and the DPD system is provided, it is possible to realize an optimal disk reproducing apparatus utilizing the characteristics of each tracking system.

[0004]

In the case of the Push Pull type tracking, the amplitude of the tracking error signal changes depending on the wavelength of the light beam and the depth of the pit portion of the disk. The depth of the pit is 1 with respect to the wavelength of the light beam.
In the case of / 8, 3/8, the amplitude of the tracking error signal is the largest, and in the case of 2/8, 4/8, the amplitude of the tracking error signal is the smallest.

[0005] Generally, the Pus of a CD-ROM disc are
h Pull tracking error signal level is CD-
It is smaller than the tracking error signal of the R disk and the CD-RW disk. Therefore, when reproducing a CD-ROM disc, if a tracking error signal is generated by the Push Pull method, the CD-R disc, C
Since a tracking error signal is smaller than that of a D-RW disc, stable tracking servo characteristics may not be obtained. In the case of the Push Pull method,
Variations in the pit depth of the disc during the manufacturing process and changes in the wavelength of the light beam due to changes in temperature greatly affect the generation of the tracking error signal, in which the magnitude of the tracking error signal changes. Further, also in the optical pickup mechanism, a variation in components for capturing the return light greatly affects the generation of the tracking error signal such that the tracking error signal is unbalanced. An object of the present invention is to provide a disk reproducing apparatus capable of selecting a tracking control method according to the characteristics of a tracking error signal.

[0006]

SUMMARY OF THE INVENTION In a device such as a disk reproducing device having a recording function, which has two types of tracking systems, a Push Pull system and a DPD system,
When the generation of the tracking error signal by the Push Pull method is affected during the reproduction of the disc, the tracking is switched to the DPD method to obtain more stable tracking servo characteristics.

Hereinafter, the present invention will be described in more detail. First
According to the invention, the disc reproducing apparatus irradiates the disc with a light beam and takes in return light, an optical pickup, a Push Pull signal generation circuit for generating a tracking error signal from the return light taken in by the optical pickup, and A DPD signal generation circuit that generates a tracking error signal from the return light captured by the optical pickup; a push pull signal generation circuit; and a detection unit that detects characteristics of each tracking error signal generated by the DPD signal generation circuit A control unit for determining a tracking error signal advantageous for applying tracking servo according to the characteristic of the tracking error signal detected by the detection unit;
h A switching unit that selects one of the tracking error signals generated by the Pull signal generation circuit or the DPD signal generation circuit, and a tracking drive unit that controls the tracking servo using the tracking error signal output from the switching unit. .

[0008] In the first invention, the detection unit is the Pus
h has a function of detecting the amplitude of the tracking error signal generated by the Pull signal generation circuit;
If the amplitude of the tracking error signal from the pull signal generation circuit does not fall within the predetermined range, the control unit sets the D
It has a function of selecting a tracking error signal generated by the PD signal generation circuit. Further, in the first invention, the detection unit has a function of detecting an amplitude of a tracking error signal generated by the Push Pull signal generation circuit and the DPD signal generation circuit, and the control unit detects the amplitude of the tracking error signal amplitude. It has a function to select the larger one. Further, in the first invention, the detection unit is configured to include the Pu
The control unit has a function of detecting the S / N of the tracking error signal generated by the sh Pull signal generation circuit and the DPD signal generation circuit, and the control unit has a function of selecting the better S / N of the tracking error signal. . Further, in the first invention, the detection unit includes the Push Pull
The control unit has a function of detecting a balance error of the tracking error signal generated by the signal generation circuit, and when the balance of the tracking error signal is equal to or higher than a certain level, the control unit controls the tracking error signal generated by the DPD signal generation circuit. Has the function of selecting

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings by using examples. FIG. 1 is a block diagram showing an embodiment of a disk reproducing apparatus according to the present invention.
It has a tracking error generation circuit based on the PD method. In the figure, a light beam 3 output from an optical pickup 2 is applied to a disk 1 and return light from the disk 1 is taken in by an optical pickup 2 and the Push Pu
11 and output to the DPD signal generation circuit 6. Push Pull signal generation circuit 5 and DPD
The detection unit 7 detects each tracking error signal generated by the signal generation circuit 6 and compares the tracking error signal with the control unit 8 to determine which tracking error signal to use. Push according to the judgment of the control unit 8
Pull signal generation circuit 5 or DPD signal generation circuit 6
The tracking error signal generated in the switching unit 9
To select the tracking signal from one of the tracking error signal generation circuits. Tracking control is performed by the tracking drive unit 10 using the selected tracking error signal.

Push described in the standards of a CD-ROM disk, a CD-R disk, and a CD-RW disk
The level of the tracking error signal according to the Pull method is shown below. CD-ROM disc: 0.04-0.07 CD-R (recorded) disc: 0.04-0.09 CD-RW (recorded) disc: 0.08-0.12 Tracking error by Push Pull method The signal level is a numerical value representing the rate of change of the return light when the light beam deviates from the center of the pit portion by 0.1 μm with respect to the magnitude of the return light when the light beam hits the center of the pit portion of the disk.

The higher the level of the tracking error signal by the Push Pull method, the larger the tracking error signal is generated. The larger the tracking error signal, the more stable the tracking servo.
When playing a disk with a small sh Pull level, it is desirable to perform tracking by the DPD method rather than the Push Pull method. For example, in the case where the optical disc such as a CD-ROM disc or a CD-R disc is distorted, if a tracking error signal of the Push Pull method is adopted, the tracking error signal is different from the reference voltage in the upper and lower peak values. Misalignment occurs. In this case, it is better to perform tracking control using the tracking error signal output from the DPD signal generation circuit 6 than to the tracking error signal output from the Push Pull signal generation circuit 5.

Therefore, the level of the tracking error signal generated by the Push Pull is detected by the detection unit 7, and when the tracking error signal affects the tracking servo characteristics, the control unit 8 makes a determination, and the switching unit If the DPD signal is selected in accordance with No. 9, the disc reproducing apparatus selects an appropriate tracking method according to the disc characteristics.

As described above, in this embodiment, the detection section 7 detects the characteristics of the tracking error signal, and the control section selects a tracking error signal that is advantageous for applying the tracking servo, thereby providing a stable tracking servo. Get the characteristics.

As a method of detecting the characteristic of the tracking error signal, for example, the detection
A function for detecting the amplitude of the tracking error signal generated from the signal generation circuit 5 is provided. If the amplitude of the tracking error signal does not fall within a certain range, the tracking error signal generated from the DPD signal generation circuit 6 is output. The selection is made by the switching unit 9. Or Push Pull
The amplitude of the tracking error signal generated by the l signal generation circuit 5 and the DPD signal generation circuit 6 is detected by the detection unit 7, the control unit 8 determines which one of the tracking error signal amplitude is larger, and the switching unit 9 selects it. To

The Push Pull signal generation circuit 5
The detection unit 7 has a function of detecting the S / N of the tracking error signal generated by the DPD signal generation circuit 6, and the control unit 8 determines which one of the S / N of the tracking error signal is better. May be selected.
Further, the detection unit 7 is provided with a function of detecting a balance deviation of the tracking error signal generated by the Push Pull signal generation circuit. That is, the detection unit 7 is provided with a function of detecting a difference between the upper and lower peak values of the tracking error signal with respect to the reference voltage. When the tracking error signal is out of balance at a certain level or more, the control unit 8 determines this, and switches the tracking error signal generated by the DPD signal generation circuit to the tracking error signal from the DPD signal generation circuit 6. Select with 9.

According to the present invention, in the disk reproducing apparatus having the tracking error generating circuits of the Push Pull system and the DPD system, the function of detecting the tracking error signal generated by each circuit and the tracking error generating system can be freely set. Since the function of selecting is added, tracking servo can be performed using an advantageous tracking error signal, and more stable tracking servo characteristics can be obtained.

[0017]

As described above, according to the present invention, more stable tracking control can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a disk reproducing apparatus according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Disc, 2 ... Optical pickup, 3 ... Light beam, 4
... Tracking error generator, 5 ... Push Pull
Signal generation circuit, 6 DPD signal generation circuit, 7 detection section,
8: control unit, 9: switching unit, 10: tracking drive unit.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D118 AA26 BA01 CA13 CA24 CB06 CD03

Claims (5)

[Claims] An optical pickup for irradiating a disk with a light beam to capture return light, a Push Pull signal generation circuit for generating a tracking error signal from the return light captured by the optical pickup, and capture by the optical pickup A DPD signal generation circuit for generating a tracking error signal from the returned light,
a detector for detecting characteristics of each tracking error signal generated by the II signal generation circuit and the DPD signal generation circuit; and advantageously performing tracking servo according to the characteristics of the tracking error signal detected by the detection unit. A switching unit that determines one of the tracking error signals generated by the Push Pull signal generation circuit or the DPD signal generation circuit in accordance with the determination result of the control unit; A disc drive comprising: a tracking drive unit that controls a tracking servo using the output tracking error signal. 2. The disk reproducing apparatus according to claim 1, wherein said detection section has a function of detecting an amplitude of a tracking error signal generated by said Push Pull signal generation circuit, and detects the amplitude of said tracking signal from said Push Pull signal generation circuit. A disk reproducing apparatus, characterized in that the control unit has a function of selecting a tracking error signal generated by the DPD signal generation circuit when the amplitude of the tracking error signal does not fall within a predetermined range. 3. The disk reproducing apparatus according to claim 1, wherein the detecting section has a function of detecting an amplitude of a tracking error signal generated by the Push Pull signal generating circuit and the DPD signal generating circuit, A disc playback device having a function of selecting a tracking error signal having a larger amplitude. 4. A disk reproducing apparatus according to claim 1, wherein said detecting section has a function of detecting an S / N of a tracking error signal generated by said Push Pull signal generating circuit and said DPD signal generating circuit. A disk reproducing apparatus characterized in that the control unit has a function of selecting a better S / N of a tracking error signal. 5. The disk reproducing apparatus according to claim 1, wherein said detecting section has a function of detecting a deviation of a tracking error signal generated by said Push Pull signal generation circuit, and detecting a deviation of the tracking error signal. A disk reproducing apparatus characterized in that the control unit has a function of selecting a tracking error signal generated by the DPD signal generation circuit when the level is equal to or higher than a certain level.