JP2002056547A - Tracking servo control method of disk player - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tracking servo control method of a disk player capable of stably performing the track servo by surely focusing on the objective signal recording surface with respect to the disk having plural recording layers. SOLUTION: A servo adjusting value corresponding to the first signal recording surface is set to measure a tracking center value after the movement control is completed, and after that, a servo adjusting value corresponding to another signal recording surface is set to measure a tracking center value, than both tracking center values are compared with each other, and by deciding that a pickup exits on the signal recording surface having the smaller value, the tracking control is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking servo control method for a disk reproducing apparatus, and more particularly to a tracking servo control method for a disk reproducing apparatus suitable for reproducing a digital video disk having two signal recording surfaces. About.

[0002]

2. Description of the Related Art A variety of media for providing music and images have appeared along with recent technological advances. With the advance of digital technology, video and music are converted into digital signals, recorded on a disk having the same size / shape as a compact disk (CD), and the digital signals recorded on the disk are read and reproduced. Digital video disks (hereinafter abbreviated as DVDs) have come to appear.

[0003] Since DVDs record and reproduce video and music by digital signals, DVDs are superior to video tapes conventionally used for recording and reproducing video and music in that they do not deteriorate over time in image quality and sound quality. ing. DVD is
Although a disk of the same size as a CD is used, it has a data storage capacity seven times as large as that of a CD, so that it is excellent in that more data can be recorded. Due to these advantages, DVDs have been used as home audio reproduction media, as well as in-vehicle navigation devices that use a large amount of data, and auxiliary storage devices for personal computers.

As shown in FIG. 4, a DVD 41 is provided with two signal recording surfaces 42 and 43 in order to record a large amount of image data and audio data. The DVD player includes an optical pickup 44 for reading data from the signal recording surfaces 42 and 43,
When reading data from the signal recording surface 42, the laser beam emitted from the optical pickup 44 is irradiated so that the laser light is focused on the signal recording surface 42. When data is read from the other signal recording surface 43, the focus of the pickup 44 is switched so as to match the signal recording surface 43, and data can be read from any of the signal recording surfaces 42 and 43. I can do it.

[0005]

Due to its convenience, DVDs have been used in various environments such as in-vehicle DVD players and portable DVD players in addition to in-vehicle navigation devices. As a result, external vibrations are often applied to the DVD player. In general, a reproducing apparatus for reading data recorded on a signal recording surface by an optical pickup, for example, a CD player, loses focus when vibration is applied from the outside, causing sound skipping and data reading errors. . The same applies to a DVD player, but as a countermeasure against this, a storage unit called a buffer memory (not shown) is usually provided, and a predetermined amount or more of data is read from a disk in advance and stored in the buffer memory. When vibration is applied from the outside, the data stored in the buffer memory is read to avoid skipping or a reading error.

[0006] By the way, there are cases where the focus does not match the target signal recording surface due to vibration. For example, when the optical pickup is focused on one signal recording surface on a DVD disk (focus search) or when a kick pulse is used to jump to a signal recording surface on which target data is recorded (layer jump), an external device is used. If vibration is applied, the vibration may cause a situation where the focus does not match the target signal recording surface. In such a case, the above-mentioned buffer memory method cannot cope,
The following problems occur.

As shown in the flow chart of FIG. 5, the tracking servo control of the conventional disk reproducing apparatus is performed by a system controller by using a servo adjustment value (balance adjustment value or gain adjustment value of tracking or focus servo) of a target signal recording surface. To the servo system (step 5
01), and then a focus search is performed (step 50).
2) After the focus search, a series of operations of turning on the tracking servo (Step 503), acquiring ID information from the signal recording surface and confirming the layer (Step 504) are performed. In step 504, I
Since the D information includes information indicating the signal recording surface (layer), the system controller refers to the layer identification information and confirms that the target signal recording surface is in focus. Thereafter, data is read.

In the above-described tracking servo control, an external vibration is applied during a focus search, and as a result,
The focus may not be on the target signal recording surface in some cases. Even in such a case, the system controller attempts to start reproduction of data by turning on the tracking servo assuming that the focus of the optical pickup is on the target signal recording surface. However, in practice, the optical pickup is focused on another signal recording surface, and the tracking servo system operates with the servo adjustment value of the target signal recording surface. For this reason, the tracking servo becomes unstable or the tracking servo cannot be performed. As a result, the ID information and data cannot be read. When the servo becomes unstable, an abnormal voltage may be applied to the actuator of the optical pickup, and the motor may burn.

Although the above is the case of the focus search, in the case of a layer jump, the focus may be erroneously focused on another signal recording surface due to vibration or the like. Therefore, there is a problem that data cannot be read.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to reproduce a disc in which the focus can be surely adjusted to a target signal recording surface and tracking servo can be performed stably. An object of the present invention is to provide a tracking servo control method for a device.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a tracking servo control method for a disk reproducing apparatus for reading out a recording signal from a double-layer disk having two surfaces as signal recording surfaces, and picking up a predetermined first signal recording surface. Set the servo adjustment value according to this first signal recording surface when moving, measure the tracking center value after the movement control is completed, and then adjust the servo adjustment according to the other second signal recording surface A tracking center value is measured by setting a value, and the two tracking center values are compared, and it is determined that a pickup is present on the smaller signal recording surface, and tracking control is performed. That is, when it is determined that the pickup exists on the first signal recording surface, the tracking servo is turned on, and when it is determined that the pickup does not exist, the operation of moving the pickup to the predetermined first signal recording surface is performed again. In this way, the signal recording surface that is in focus can be recognized at the time of a focus search or a layer jump, and even if another signal recording surface is focused by mistake, the signal recording surface intended for focusing can be recognized. The tracking servo can be stably performed by moving. As a result, according to the present invention, data can be reliably read, and no abnormal voltage is applied to the actuator of the pickup, and burn-in of the servomotor can be prevented.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (A) Outline of the present invention DPD adjustment is performed to maintain an optical pickup used in a DVD reproducing apparatus on the center line of a target track. DPD adjustment means that the pit depth is λ / 4
(Λ is the wavelength of the light beam) This is a method for correcting the phase difference of the tracking error TE generated when the optical pickup is different from the objective lens included in the optical pickup by a predetermined amount (for example, ± 0.3 mm) in the inner and outer peripheral directions of the track. ), The phase of the optical pickup detection signal is adjusted so that the deviation of the center value (TE center value) of the TE signal from the 0 level becomes minimum. TE center value is TE
The adjustment value that is the center value between the peak value and the bottom value of the signal and that minimizes the deviation of the TE center value from 0 is called the DPD adjustment value.

When reading data from a predetermined signal recording surface using an optical pickup, first, a tracking and focus servo adjustment value (balance adjustment value, gain adjustment value, DPD adjustment value) of a target signal recording surface is read by a servo system. Is set, the focus search is performed, and after the focus search is completed, the TE center value is calculated. Similarly, the servo adjustment values of other signal recording surfaces are set to calculate the TE center value.
Next, the two TE center values are compared, and when the TE center value when the servo adjustment value of the target signal recording surface is set is smaller, it is determined that the pickup is focused on the target signal recording surface. Judgment is made, the tracking servo is turned on, and data is read out. On the other hand, when the TE center value when the servo adjustment value of another signal recording surface is set is smaller, the focus search or the layer jump is performed again because the pickup is not focused on the target signal recording surface.

(B) Embodiment FIGS. 1 and 2 are block diagrams of a tracking servo system and a focus servo system of a disk reproducing apparatus for realizing the present invention. In the tracking servo system shown in FIG.
An optical pickup for reading data from each signal recording surface 2a, 2b of D2 is shown. The optical pickup 1 includes an objective lens 1a, a four-divided photodetector 1b, and a tracking actuator (not shown), and irradiates the signal recording surfaces 2a and 2b with laser light from the objective lens 1a and reflects the laser light. The data recorded on the signal recording surfaces 2a and 2b is read from the light. And DVD
2 is recorded on each signal recording surface 2a, 2b,
It is composed of data 2c and ID information 2d indicating its contents. The ID information 2d includes a layer identifier,
An ID error detection code, copyright management information, an error detection code, and the like are recorded.

Reference numeral 3 denotes an I / V conversion unit for performing I / V conversion on signals output from the respective photodetectors A, B, C, and D of the four-split photodetection unit 1b and outputting the signals. (Phase adjuster), 6 is a tracking error detector that generates a TE signal from a signal output from the optical pickup 1. The signals output from the photodetectors A and B of the four-split photodetector 1b are input to the tracking error detector 6 via the delays 4 and 5, while the signals output from the photodetectors C and D are input as they are. You.

The delay units 4 and 5 include a microcomputer unit 11 described later.
The delay units 4 and 5 adjust the phase of the signal output from the I / V conversion unit 3 and correct the phase offset of the tracking error based on the DPD adjustment value. It has become. here,
The DPD adjustment value is adjusted so that the deviation from the zero level of the TE center value when the objective lens 1a included in the optical pickup is shifted by a predetermined amount (for example, ± 0.3 mm) in the inner and outer peripheral directions is minimized. The value is measured in advance and stored in a storage unit (not shown) of the microcomputer unit 11.

The tracking error detector 6 adjusts signals output from the photodetectors A to D of the four-split photodetector 1b to output a TE signal (φ (A + D) −φ (B + C)).

Reference numeral 7 denotes a balance adjusting unit for adjusting the balance of tracking caused by variations in elements of the optical pickup 1. Reference numeral 8 denotes a T for detecting a TE center value from a TE signal.
An E center detection unit, 9 is a tracking servo control unit for performing servo control such as on / off of a tracking servo, 10 is a gain adjustment unit that adjusts a gain so as to be a target servo gain, and 11 is a microcomputer unit ( System controller), 12 is an equalizer unit (phase compensation unit),
Reference numeral 13 denotes a tracking driver for driving the tracking actuator of the optical pickup 1. The balance adjustment unit 7 and the gain adjustment unit 10 include a microcomputer 11
The tracking balance adjustment value and the tracking gain adjustment value output from are input respectively, and each performs the balance adjustment and the tracking gain adjustment based on each adjustment value.

The TE center detector 8 detects T from the TE signal.
This is for calculating the center value of the E signal, and receives the TE signal output from the balance adjustment unit 7. Then, the TE center detecting section 8 detects a peak value and a bottom value of the input TE signal, and calculates and outputs a center value between the peak value and the bottom value as a TE center value.

Although not specifically shown, the microcomputer unit 11
A storage unit for recording the tracking servo adjustment values of the signal recording surfaces 2a and 2b and the detected TE center value; the TE center value output from the TE center detection unit 8; Is entered. The tracking servo adjustment values are a tracking balance adjustment value, a DPD adjustment value, and a track gain adjustment value for each of the signal recording surfaces 2a and 2b, and are measured and stored in advance. When the optical pickup 1 performs a track jump to the target signal recording surface, the microcomputer unit 11 outputs the servo adjustment values of the signal recording surface to the delay units 4, 5, the balance adjustment unit 7, and the gain adjustment unit 10, respectively. It has become. The storage unit of the microcomputer unit 11 also stores a focus balance adjustment value and a focus gain adjustment value, which will be described later, in association with the signal recording surface. When executing the focus search and the layer jump, the microcomputer unit 11 The focus balance adjustment value and the focus gain adjustment value of the target signal recording surface are set.

FIG. 2 is a connection diagram of the focus servo system, and the same parts as those in FIG. 1 are denoted by the same reference numerals. Reference numeral 21 denotes a focus error signal generation unit that outputs a focus error signal FE from a signal output from the optical pickup;
2 is a focus search signal generation circuit for generating a focus search signal FS, 23 is a signal switching circuit section for selecting and outputting the focus search signal FS and focus error signal FE, 24 is a balance adjustment section, and 25 is a focus servo gain. A gain adjustment unit for adjusting the gain so as to obtain a value; 26, an equalizer unit (phase compensation unit); 27, a layer jump pulse signal generation unit for instantaneously jumping the focus from one signal recording surface to the other signal recording surface;
Reference numeral 28 denotes a focus driver that drives a focus actuator (not shown) based on the focus error signal FE or the focus search signal FS to control the distance between the objective lens 1a and the signal recording surface of the DVD 2.

(C) Processing Next, a tracking servo control method for the disk reproducing apparatus according to the present invention will be described with reference to FIG. First, the microcomputer unit 1
1 transfers a DPD adjustment value, a tracking pulse adjustment value, and a tracking gain adjustment value, which are tracking servo adjustment values of a target signal recording surface, to the delay units 4, 5, the balance adjustment unit 7, and the gain adjustment unit 10, respectively. set. The microcomputer unit 11 includes a focus balance adjustment unit 24
, And the gain adjustment unit 10 sets the focus gain adjustment value. (Step 101).

Next, the microcomputer unit 11 controls the focus search signal generation circuit 22 to generate the focus search signal FS, and controls the signal switching circuit unit 23 to execute the focus search (step 102).

After the pickup moves to the focus servo available area, the microcomputer section 11 switches the focus servo control from the focus search signal FS to the focus error signal FE. Then, TE center detector 8
Detects the TE center value A from the TE signal output from the tracking error detector 6 (step 103),
This TE center value A is stored in the storage unit of the microcomputer unit 11. When the servo adjustment value according to the target signal recording surface is set and the focus of the optical pickup 1 matches the target signal recording surface, the TE center value becomes smaller. However, when the focus is adjusted to a signal recording surface different from the intended signal recording surface due to vibration, the TE center value increases.

Next, the microcomputer unit 11 calculates a servo adjustment value of a signal recording surface different from the target signal recording surface, that is, a DPD adjustment value, a tracking and focus balance adjustment value, and a gain adjustment value of another signal recording surface. Delay units 4, 5, balance adjustment units 7, 24, and gain adjustment unit 1, respectively
The data is transferred to 0 and 25 and set (step 104). Thereafter, the TE center detecting section 8 detects the TE center value B from the TE signal output from the tracking error detecting section 6 (Step 105), and stores the TE center value B in the storage section of the microcomputer section 11. When a servo adjustment value is set according to the signal recording surface on which the optical pickup is focused, the TE center value decreases.

Thereafter, the microcomputer unit 11 compares the TE center value A and the TE center value B stored in the storage unit, and finds which one is closer to 0, that is, which of the deviations from the level 0 is smaller. (Step 10
6). Here, when the TE center value A is closer to 0 than the TE center value B, the microcomputer unit 11 determines that the optical pickup 1 is in focus on the target signal recording surface, and After setting the servo adjustment value for the surface, the tracking servo is turned on (step 107). Thereafter, the ID recorded on the track of the target signal recording surface
The information 2d is acquired, and by referring to the layer identification information included in the ID information, it is confirmed whether or not the target signal recording surface is in focus. After the confirmation, data reading is started.

On the other hand, when the TE center value B is closer to 0 than the TE center value A in step 106, the microcomputer unit 11 determines that the optical pickup 1 is focused on another signal recording surface. Judge, step 10
1 and the subsequent operation is repeated again.

[0028]

As described above, according to the present invention, when the pickup is moved to the predetermined first signal recording surface, a servo adjustment value corresponding to the first signal recording surface is set, and after the movement control is completed. , Measure the tracking center value, and then
Set the servo adjustment value according to the other second signal recording surface, measure the tracking center value, compare both tracking center values, determine that the pickup is present on the smaller signal recording surface, and perform tracking control I do. When it is determined that the pickup exists on the first signal recording surface, the tracking servo is turned on, and when it is determined that the pickup does not exist, the operation of moving the pickup to the predetermined first signal recording surface is performed again. Therefore,
ADVANTAGE OF THE INVENTION According to this invention, the signal recording surface which is in focus at the time of a focus search or a layer jump can be recognized, and even if the focus search is mistakenly focused on another signal recording surface, the signal recording surface intended for focusing can be recognized. The tracking servo can be stably performed by moving. As a result, data can be read reliably, and further, no voltage is applied to the actuator of the optical pickup, and burn-in of the servo motor can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a tracking servo system of a disk reproducing apparatus that realizes the present invention.

FIG. 2 is a configuration diagram of a focus servo system of a disk reproducing apparatus that realizes the present invention.

FIG. 3 is a flowchart for explaining a tracking servo control method of the disk reproducing apparatus of the present invention.

FIG. 4 is a schematic diagram showing the structure of a disk having two signal recording surfaces.

FIG. 5 is a flowchart for explaining a conventional tracking servo control method of a disk reproducing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical pickup 1a Objective lens 1b 4 division light detection part 2 DVD 2a, 2b Signal recording surface 2c Data 2d ID information 3 I / V conversion part 4,5 Delay part 6 Tracking error detection part 7,24 Balance adjustment part 8 TE center Detection unit 9 Tracking servo control unit 10, 25 Gain adjustment unit 11 Microcomputer unit 12, 26 Equalizer unit 13 Tracking driver 21 Focus error signal generation unit 22 Focus search signal generation circuit 23 Signal switching circuit unit 27 Layer jump pulse signal generation unit 28 Focus driver

Claims (2)

[Claims] In a tracking servo control method of a disk reproducing apparatus for reading out a recording signal from a dual-layer disk having two surfaces as signal recording surfaces, when a pickup is moved to a predetermined first signal recording surface, Set the servo adjustment value according to the signal recording surface, measure the tracking center value after completing the movement control, and then set the servo adjustment value according to the other second signal recording surface and set the tracking center value. A tracking servo control method for a disk reproducing apparatus, comprising: measuring and comparing both tracking center values; determining that a pickup is present on a smaller signal recording surface; and performing tracking control. 2. A tracking servo is turned on when it is determined that a pickup is present on the first signal recording surface, and when the pickup is determined not to be present, an operation of moving the pickup to a predetermined first signal recording surface is performed again. 2. The tracking servo control method for a disk reproducing apparatus according to claim 1, wherein: