JPH09320178A - Disk-discriminating method for digital disk player - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate where a disk loaded on a player is a single-layer disk or a dual-layer disk. SOLUTION: A counter 26 counts the S curve number of the focus error signal EF which is generated at the time of focus search, and a system controller 24 discriminates whether the disk 11 is a dual layer disk or a single layer disk based on the S curve number. Also the controller 24 discriminates whether the disk 11 is the dual-layer disk or the single-layer disk based on the amplitude of the focus error signal FE which is generated at the time of focus search.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc identification method, and more particularly to a digital disc player for reading and reproducing recorded data from a dual layer disc having two signal recording layers or a single layer disc having only one signal recording layer. Disc identification method.

[0002]

2. Description of the Related Art Digital video disc players (DV
Discs of D player) include a single layer disc having only one signal recording layer and a dual layer disc having two signal recording layers. FIG.
(A) is a structural diagram of a single layer disc, and RL
Is a signal recording layer, SR is a transparent plastic layer (base), and PL is a protection layer that protects the signal layer.
FIG. 4B is a structural diagram of the dual layer disc,
It has a dual structure in which two discs each having signal recording layers RL1 and RL2 and transparent plastic layers (bases) SR1 and SR2 are laminated via a space layer SPL. Incidentally, LS is an objective lens. With conventional discs such as CD, there was no dual layer disc, so single layer (CD etc.)
It was only a disc playback technology.

[0003]

From the viewpoint of compatibility, D
It would be convenient for the user if the VD player can play both single layer discs and dual layer discs. However, in order to be able to play both discs, it is necessary to identify whether the disc loaded in the player is a single layer disc or a dual layer disc because the standards are different. From the above, an object of the present invention is to provide a disc identifying method capable of identifying whether a disc loaded in a player is a single layer disc or a dual layer disc.

[0004]

According to the present invention, the above object is to provide a focus search means, a means for counting the number of S curves of a focus error signal generated during the focus search, and a disc based on the number of S curves. It is achieved by means of determining whether it is a dual layer disc or a single layer disc. Further, the above object is achieved according to the present invention by means for performing a focus search, and means for determining whether the disc is a dual layer disc or a single layer disc based on the amplitude of a focus error signal generated during the focus search. It

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION

(A) Outline of the Present Invention In a DVD player, a focus servo control device is provided to converge the laser beam on the signal recording surface of the disc. The focus servo control device generates a focus error signal having a voltage value corresponding to the distance between the objective lens position and the focus position (the position of the objective lens when the focus of the objective lens coincides with the signal recording surface),
The position of the objective lens with respect to the disc is controlled so that the error signal becomes zero. In order for the focus servo control device to be servo-controllable, the distance between the objective lens and the disc signal surface must be close to the depth of focus to some extent. Therefore, when the disc is mounted on the player, it is necessary to move the objective lens to a position where the focus servo can be performed. Therefore, 1 / 2H
A focus search signal which is a triangular wave signal of about z is generated to move the objective lens to a position where focus servo is possible, for example, a focus position (focus search control),
After that, the focus servo control is performed by the focus error signal.

At the time of such focus search, in the case of a single layer disc, as shown in FIG. 1A, only one S curve of the focus error signal FE can be observed during the half cycle A of the focus search signal FS. However, in the case of a dual layer disc, two S curves can be observed as shown in FIG. Therefore, in the first disc identification method of the present invention, when there is one S curve that can be observed during focus search, it is determined to be a single layer disc, and when there are two S curves, it is determined to be a dual layer disc.

The reflectance of the single layer disc is different from that of the dual layer disc. The reflectance of the single layer disc is 70% and the reflectance of the dual layer disc is 25 to 45%. Therefore, the amplitude P _{1 of the} S curve detected during the focus search of the single layer disc is larger than the amplitude P _{2 of the} S curve detected during the focus search of the dual layer disc. Therefore, in the second disc identifying method of the present invention, a single layer disc is determined when the amplitude of the S curve observed during focus search is large, and a dual layer disc is determined when the amplitude of the S curve is small.

(B) First Embodiment of the Present Invention FIG. 1 is a block diagram of the essential parts of a DVD player according to the first embodiment of the present invention. Reference numeral 11 denotes a disc, which is a single layer disc or a dual layer disc. 12
Is an optical pickup, and a focus actuator 12 for moving the position of the objective lens 12a or the objective lens.
b, a photo diode (not shown) and the like. 1
3 is an RF amplifier, 14 is an error signal generator that outputs a focus error signal FE from a signal output from an optical pickup, and 15 is a gain controller (attenuator or gain) that controls a focus servo gain based on a servo coefficient described later. (Variable amplifier), 16 is a phase compensation circuit, 17 is a focus search signal generation circuit that generates the focus search signal FS, and 18 is signal switching that selects and outputs the focus search signal FS and the focus error signal FE. A circuit, 19 is an actuator driver that drives the focus actuator 12b based on the focus error signal FE or the focus search signal FS to control the distance between the objective lens 12a and the signal recording surface of the disc, and 20 is a sled motor. , 21 are spindle motors.

Reference numeral 22 denotes the level (peak value) of the focus error signal FE when the objective lens 12a is passing near the in-focus position of the signal recording layer by the focus search signal FS during focus search control. An error signal level detection circuit for detecting the signal level, and an AD converter (AD) for converting the detected focus error signal level into a digital value.
C) and 24 are system controllers for executing focus servo control, servo gain coefficient determination control, disc identification control, and the like. The reference numeral 25 compares the level Lf of the focus error signal FE output from the error signal generation circuit 14 during the focus search control with the set level Ls to obtain Lf.
Comparator circuit that outputs a high level signal when> Ls, 2
Reference numeral 6 is a counter for counting the number of high level signals output from the comparison circuit 25. 27 is a signal processing unit, R
28 demodulates MPEG data based on the signal input from the F amplifier, and also performs digital signal processing such as error correction processing, separation processing of MPEG video data and MPEG audio data, and extraction processing of address information, 28 is MPEG video MPE that decodes image data from data
A G video decoder 29 is an MPEG audio decoder for decoding PCM audio data from MPEG audio data.

When the disc 11 is loaded in the player,
The system controller 24 controls the focus search signal generating circuit 17 so that the focus search signal F is a triangular wave of (1/2) Hz as shown in FIGS. 1 (a) and 1 (b).
S is generated, and the focus search signal FS causes the objective lens 12a to move toward and away from the disk surface.
The error signal level detection circuit 22 detects the peak level P ₁ or P ₂ of the focus error signal FE when the objective lens 12a passes near the focus position of the signal recording layer.
(See FIGS. 1A and 1B), the system controller 24 determines the servo gain coefficient based on the detected peak level P ₁ or P _{2 so} that the gain of the servo loop becomes an optimum value. g is determined, and the gain control unit 15
Set to.

Further, in parallel with the gain determination control, the comparison circuit 25 causes the focus error signal level Lf and the set level L to be set.
When s is compared and Lf> Ls, a high level signal is output, and the counter 26 counts the number of high level signals. When the disc 11 is a single layer disc, as shown in FIG. 1A, Lf> Ls is satisfied only once during the half cycle A of the focus search signal FS.
The count value of 6 becomes 1. On the other hand, when the disc is a dual layer disc, as shown in FIG. 1B, Lf> L twice during the half cycle A of the focus search signal FS.
Therefore, the count value of the counter 26 becomes 2. The system controller 24 uses the focus search signal FS
The value counted by the counter 26 during the half cycle A of is read, and if the count value is 1, it is determined that the disc is a single layer disc, and if the count value is 2, it is the dual layer disc and stored. , Controls related to the type of disk.

After the above gain control and disc identification control have been completed, the objective lens 12a outputs the focus search signal F.
When the focus error signal FE becomes zero due to further movement by S, the system controller 24 causes the signal switching circuit 18
The focus error signal FE is input to the actuator driver 19 instead of the focus search signal FS. As a result, focus servo control is performed thereafter.

(C) Second Embodiment FIG. 3 is a block diagram of the essential parts of a DVD player according to the second embodiment of the present invention. The same parts as those in the first embodiment of FIG. There is. The second embodiment is different from the first embodiment in that, instead of the comparison circuit 25 and the counter 26 in the first embodiment, a single / dual identification unit for identifying the disc type based on the peak value of the focus error signal FE. This is the point where 30 is provided.

As described with reference to FIG. 1, the reflectance is different between the single layer disc and the dual layer disc. The reflectance of the single layer disc is 70% and the reflectance of the dual layer disc is 25 to 45%. Therefore, the amplitude P _{1 of the} S curve detected during the focus search of the single layer disc is larger than the amplitude P _{2 of the} S curve detected during the focus search of the dual layer disc. Therefore, the single / dual identification unit 3
0 indicates an error signal level detection circuit 2 during focus search
The amplitude value of the S-curve detected by 2 is compared with the set level L, and when the amplitude value is equal to or higher than the set level L, it is determined that the disk 11 is a single layer disk, and when the amplitude value is equal to or lower than the set level, the dual layer is used. It is determined that the disc is a disc, and the determination result is input to the system controller 24. The system controller 24 stores the disc identification information and performs control relating to the disc type. According to the second embodiment, unlike the first embodiment, it is not necessary to move the objective lens largely during the focus search, and the servo may be turned on at the first S curve, so that the search time can be shortened.

In the second embodiment as described above, the single / dual discrimination section 30 is provided to judge the type of the disk, but the system controller 24 determines the servo gain coefficient g based on the amplitude value input from the error signal level detection circuit 22. It can also be configured to identify the type at the same time as the determination. Although the present invention has been described above with reference to the embodiments, the present invention can be variously modified according to the gist of the present invention described in the claims, and the present invention does not exclude these.

[0016]

As described above, according to the present invention, the number of S curves of the focus error signal generated during focus search is counted, and whether the disc is a dual layer disc or a single layer disc is determined based on the number of S curves. Since the disc type is configured to be determined, the disc type can be identified with a simple configuration, and reproduction can be performed regardless of whether it is a single layer disc or a dual layer disc.
Further, since the disc type is identified in parallel with the focus search, the time until the start of reproduction can be shortened.

Further, according to the present invention, it is configured to judge whether the disc is a dual layer disc or a single layer disc based on the amplitude of the focus error signal generated at the time of focus search. The disc type can be identified by, and it becomes possible to play back whether it is a single layer disc or a dual layer disc. Further, since the disc type is identified in parallel with the focus search, the time until the start of reproduction can be shortened. Furthermore, since it is not necessary to move the objective lens largely during focus search, the search time can be shortened.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of the present invention.

FIG. 2 is a configuration diagram of a main part of the DVD player according to the first embodiment of the present invention.

FIG. 3 is a main part configuration diagram of a DVD player according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of a disc structure.

[Explanation of symbols]

 11 ... Disk 14 ... Error signal generator 17 ... Focus search signal generator 22 ... Error signal level detector 24 ... System controller 25 ... Comparison circuit 26 ... Counter 30 ... Single / dual discriminator

Claims (2)

[Claims] 1. An S curve of a focus error signal generated during focus search in a digital disc player for reading and reproducing recorded data from a dual layer disc having two signal recording layers or a single layer disc having only one signal recording layer. A disk identifying method, characterized by counting the number and judging whether the disk is a dual layer disk or a single layer disk based on the number of S curves. 2. The amplitude of a focus error signal generated during focus search in a digital disc player for reading and reproducing recorded data from a dual layer disc having two signal recording layers or a single layer disc having only one signal recording layer. A disc identifying method characterized by determining whether the disc is a dual layer disc or a single layer disc based on the disc.