JP2005071478A - Optical disk device and tracking control method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of performing accurate tracking control and stable data reading by always setting a tracking error signal to a proper polarity in an optical disk device. <P>SOLUTION: The level of a PE signal which is the sum signal of a reflected light quantity from an optical disk is detected, the polarity of a tracking error signal is discriminated based on the PE sinal level, and the polarity of the tracking error signal is controlled based on the result of the discrimination. At least when the detected PE signal level is high, the polarity of the tracking error signal is reversed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a tracking control technique for an optical disc apparatus.

  As conventional techniques related to the present invention, for example, JP 2000-99965 A (Patent Document 1), JP 2002-298385 A (Patent Document 2), and JP 9-167353 A (Patent Document 3). There is what is described in. In Japanese Patent Laid-Open No. 2000-99965, the peak levels of the light intensity signals in the pit area and the groove area are set in order to accurately determine the area between the pit area and the groove area and perform appropriate tracking servo control. A technique is described in which a discrimination is made between a pit area and a groove area by detecting and comparing the threshold level and the peak level with a level approximately in the middle as a threshold value. Japanese Patent Application Laid-Open No. 2002-298385 discloses the phase / wobble detection based on the phase information to detect the phase of the wobble signal in order to improve the reproduction reliability in the disk drive device. Describes a technique for detecting the moving direction of a laser spot during traversing based on the phase difference between the tracking error signal and the tracking error signal. Japanese Patent Application Laid-Open No. 9-167353 discloses a land / groove signal whose polarity is inverted so that the optical recording / reproducing apparatus can perform just tracking even in the seek between the land and the groove. A technique is described in which tracking control is performed.

JP 2000-99965 A JP 2002-298385 A JP-A-9-167353

All of the conventional techniques described in the above-mentioned patent documents are techniques for an optical disc having a land area and a groove area, and are difficult to apply to an optical disc having only a pit area and an area in between.
In view of the situation of the prior art, the problem of the present invention is that in the optical disc apparatus, even when an optical disc having only a pit region and a region between them is used as a recording medium, the polarity of the tracking error signal is always set to an appropriate polarity, It is to enable stable data reading by accurate tracking control.
An object of the present invention is to provide a technique capable of solving such problems.

  In order to solve the above problems, in the present invention, basically, in an optical disc apparatus, the level of a PE signal, which is a sum signal of the amount of reflected light, is detected from the optical disc, and a tracking error signal is detected based on the detected PE signal level. The polarity is discriminated, and the polarity of the tracking error signal is controlled based on the discrimination result. At least when the detected PE signal level is high, the polarity of the tracking error signal is inverted. Specifically, the present invention proposes an optical disc apparatus having the above basic configuration and a tracking control method using the above basic operation over time.

  According to the present invention, in the optical disc apparatus, tracking control can be performed in a state where the tracking error signal is always set to an appropriate polarity. As a result, accurate tracking control and stable data reading can be performed.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration example of an optical disc apparatus as an embodiment of the present invention.
In FIG. 1, 1 is an optical disc in which information is recorded in a pit area such as a CD-ROM, and 2 is a laser beam irradiating the optical disk 1 to record or record information in the pit area of the optical disk 1. An optical pickup that reads out the read information, 3 is a tracking control circuit that forms and outputs a tracking control signal based on the tracking error signal read out by the optical pickup 2, and 4 is an actuator based on the tracking control signal. 5 is an actuator that changes the position and orientation of the optical system in the optical pickup 2, and 6 is a PE signal (PE: Pull) as a sum signal of the amount of light reflected from the optical disk 1 taken in from the optical pickup 2. -In Error), a PE signal as a PE signal detecting means for detecting the level. The bell detection circuit 7 controls the entire apparatus, determines the polarity of the tracking error signal based on the detected PE signal level, and forms and outputs a signal for controlling the polarity of the tracking error signal based on the determination result. , A polarity control means or a microprocessor unit (hereinafter referred to as MPU) as the polarity control means.

  In the above configuration, the PE signal taken from the rotating optical disk 1 by the optical pickup 2 is input to the PE level detection circuit 6. The PE level detection circuit 6 detects the maximum level and the minimum level of the PE signal. The level of the PE signal is relatively low when the light spot is located in the pit area, and relatively when the light spot is located in an area between the pit area and the pit area (hereinafter referred to as a non-pit area). Become a high level. After the maximum level and the minimum level of the PE signal are detected, the tracking control is turned on. In the tracking control ON state, the PE level detection circuit 6 detects the level of the PE signal again.

  The PE signal level detected again is substantially equal to the minimum level when the light spot is positioned in the pit area and is tracking-controlled, whereas the light spot is tracked and controlled in the non-pit area. If it is, it becomes substantially equal to the maximum level. The MPU 7 determines the polarity of the tracking error signal based on the detected PE signal level, and forms a signal for controlling the polarity of the tracking error signal based on the determination result. That is, when the PE signal level is substantially equal to the minimum level, it is determined that the tracking error signal has a proper polarity that is not inverted (hereinafter referred to as non-inverted polarity), and the polarity of the tracking error signal is not inverted. Then, a control signal for maintaining the same polarity is generated and output to the tracking control circuit 3. On the other hand, when the PE signal level is substantially equal to the maximum level, it is determined that the tracking error signal is inverted and not in a proper polarity (hereinafter referred to as inverted polarity), and tracking control is turned off once to perform tracking. The polarity of the error signal is reversed, and a control signal is generated so that the position of the light spot returns from the non-pit area to the pit area and is output to the tracking control circuit 3.

  The tracking control circuit 3 inverts the polarity of the tracking error signal according to the control signal from the MPU 7, and forms and outputs a tracking control signal based on the tracking error signal in the state. To do. That is, when the PE signal level is substantially equal to the minimum level, the polarity of the tracking error signal is not inverted and is set to the non-inverted polarity as it is, and a tracking control signal corresponding to the tracking error signal of the non-inverted polarity is formed. And the tracking control is performed with the light spot positioned in the pit area as it is. Further, when the PE signal level is substantially equal to the maximum level, the polarity of the tracking error signal is inverted, a tracking control signal corresponding to the tracking error signal of the inverted polarity is formed and output, and the light spot is not Tracking control is performed with the pit area returned to the pit area. The driver 4 forms an actuator driving signal based on the tracking control signal, and drives the actuator 5 by the driving signal. The actuator 5 changes the position and posture of an optical system such as an objective lens, and the light spot performs a tracking operation within the pit region.

2A and 2B are diagrams for explaining the operation of the optical disk apparatus of FIG. 1, wherein FIG. 2A is a PE signal waveform, FIG. 2B is a tracking error signal waveform having an inverted polarity, and FIG. 2C is a tracking obtained by inverting the waveform of FIG. It is an error signal waveform. In the following description, the same reference numerals as those in FIG.
2, A is a PE signal waveform detected by the PE level detection circuit 6 (FIG. 1), B is a tracking error signal waveform at that time, C is a tracking error signal waveform with the polarity of B inverted, t the time, T ₁ is a period in which the tracking control is turned off, T ₂ is a period in which the tracking control is turned on, A ₁ is the PE signal waveform A in the tracking control oFF period, A ₂ is the PE signal waveform A in the tracking control on period , B ₁ is the tracking error signal waveform B in the tracking control oFF period, B ₂ is a tracking control the tracking of the on-period error signal waveform B, C ₁ is the tracking error signal waveform C in the tracking control oFF period, C ₂ tracking control on period the tracking error signal waveform C in, t ₁ is the tracking system The point to be turned on, p is the period corresponding to the pit area, q is the period corresponding to the non-pit area, max is the maximum value of the PE signal level when tracking control is off, min have the same minimum value.

  When the level of the PE signal A in the tracking control ON state is a high level (= a level substantially equal to the maximum value max of the PE signal level) (FIG. 2A), the MPU 7 (FIG. 1) has a non-light spot. It is determined that the tracking error signal B (FIG. 2 (b)) located in the pit area is in the reverse polarity, and once the tracking control is turned off, the polarity of the tracking error signal B is reversed and the tracking error signal C ( In place of FIG. 2 (c), a control signal for returning the position of the light spot from the non-pit region to the pit region is formed and output to the tracking control circuit 3 (FIG. 1) side. Further, when the level of the PE signal A in the tracking control ON state is the Low level (= a level substantially equal to the minimum value min of the PE signal level), the MPU 7 is positioned in the pit area and the tracking error signal is not. It is determined that the polarity is inverted, and a control signal for maintaining the polarity of the tracking error signal as it is without being inverted is formed and output to the tracking control circuit 3.

  The operations of the optical disk apparatus described in FIGS. 1 and 2, particularly the tracking error signal polarity determination by the MPU 7 and the tracking error signal polarity control or the tracking control output signal polarity control based on the determination result, It is assumed that the operation is performed by the MPU 7 executing the operation procedure according to the set program. Further, it is assumed that the program is stored in a memory in the optical disk device or a hard disk to be mounted.

  According to the above embodiment, even when the polarity of the tracking error signal is inverted, it can be corrected to an appropriate polarity. As a result, accurate tracking control and stable data reading can be performed. Even when the polarity of the tracking error signal is inverted due to factors such as the pit depth, the polarity can be corrected.

  In the above embodiment, when the PE signal level is High level, the MPU 7 forms and outputs a control signal that inverts the polarity of the tracking error signal to the tracking control circuit 3. For example, the MPU 7 may generate and output a control signal that inverts the polarity of the tracking control signal to the tracking control circuit 3. In the above embodiment, the case where the polarity of the tracking error signal is inverted due to the light spot being located in the non-pit area has been described. However, for example, the polarity of the tracking error signal depends on factors such as the pit depth. The present invention can also be applied when is inverted.

It is a figure which shows the structural example of the optical disk apparatus as an Example of this invention. FIG. 2 is an operation explanatory diagram of the optical disc apparatus of FIG. 1.

Explanation of symbols

1 ... Optical disc,
2 ... Optical pickup,
3 ... Tracking control circuit,
4 ... Driver,
5 ... Actuator,
6 ... PE level detection circuit,
7 ... MPU.

Claims (4)

An optical disk device that records or reproduces information by tracking on an optical disk,
PE signal detecting means for detecting the level of a PE signal that is a sum signal of the amount of reflected light from the optical disc;
Polarity control means for determining the polarity of the tracking error signal based on the detected PE signal level, and controlling the polarity of the tracking error signal or the output signal for tracking control based on the determination result;
An optical disc apparatus characterized in that tracking control is performed by inverting the polarity of the tracking error signal or the tracking control output signal when the detected PE signal level is high. An optical disk device that records or reproduces information by tracking on an optical disk,
PE signal detecting means for detecting the maximum level and the minimum level of the PE signal which is a sum signal of the amount of reflected light from the optical disc;
Polarity discriminating means for discriminating the polarity of the tracking error signal based on the detected PE signal level;
Based on the determination result, the polarity control means for controlling the polarity of the tracking error signal or the tracking control output signal,
If the detected PE signal level is the maximum level, the polarity of the tracking error signal or the polarity of the output signal for tracking control is inverted and the tracking control is performed, assuming that the polarity of the tracking error signal is inverted. An optical disc apparatus characterized by being configured to perform. A method for tracking control of an optical disc apparatus that records and / or reproduces information by tracking on an optical disc,
Detecting a level of a PE signal that is a sum signal of the amount of reflected light from the optical disc;
Determining the polarity of the tracking error signal based on the detected PE signal level;
Based on the determination result, the step of controlling the polarity of the tracking error signal or the polarity of the output signal for tracking control,
A tracking control method for an optical disc apparatus, wherein tracking control is performed through A method for tracking control of an optical disc apparatus that records and / or reproduces information by tracking on an optical disc,
Detecting a maximum level and a minimum level of a PE signal, which is a sum signal of the amount of reflected light from the optical disc;
Turning tracking control on;
Detecting the level of the PE signal again;
Determining the polarity of the tracking error signal based on the detected PE signal level;
Based on the determination result, turning off the tracking control;
Reversing the polarity of the tracking error signal or the tracking control output signal;
A tracking control method for an optical disc apparatus, wherein tracking control is performed through

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