JP2009116990A - Method of discriminating optical disk and optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of discriminating an optical disk, by which discrimination of a SL type and a DL type can be performed accurately. <P>SOLUTION: The method of discriminating the optical disk includes a step of adjusting a focal point of a light beam projected to an optical disk to an information recording layer being at the nearest position to the surface of the optical disk seeing from an irradiation side of the optical beam, a step of irradiating the prescribed region of the optical disk with the light beam of which the focal point is adjusted, a step of determining whether a specific information region exists or not by irradiating the prescribed region with the light beam, and a step of determining the number of the information recording layers by existence of the specific information region. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for discriminating the type of an optical disc to be reproduced or recorded in an optical disc apparatus used for reproducing information recorded on an optical disc or recording information on an optical disc. The present invention also relates to an optical disc apparatus to which such a determination method is applied.

  Conventionally, optical discs such as compact discs (CDs) and digital versatile discs (DVDs) have been widely used as optical discs. Recently, new standard optical discs such as Blu-ray discs (BD) have also appeared. This Blu-ray disc has a higher recording density and can record a large amount of information, and is expected to become popular in the future.

  By the way, Blu-ray discs include BD-RE that is a rewritable optical disc standard, BD-R that is a write-once optical disc standard, and BD-ROM that is a read-only optical disc standard. In each standard, a single layer (SL) type optical disc having only one information recording surface and a dual layer (DL) type optical disc having two information recording layers have been developed.

  As described above, since there are many types of Blu-ray discs, when reproducing or recording a Blu-ray disc using an optical disc device, it is necessary to first determine the type of Blu-ray disc inserted in the optical disc device. is there. In other words, it is necessary to determine whether the Blu-ray disc inserted in the optical disc apparatus is BD-RE, BD-R, or BD-ROM. Further, it is necessary to further discriminate whether the optical disc is of the SL type or the DL type, assuming that the discrimination has been made.

  As a method for determining whether a Blu-ray disc is a BD-RE, a BD-R, or a BD-ROM, conventionally, for example, a method using the difference in reflectance is used. That is, a method of discriminating the type of Blu-ray disc based on the signal level of reflected light reflected on the information recording layer at that time by irradiating the information recording layer of the Blu-ray disc with a light beam (for example, wavelength 405 nm) is performed. It has been broken.

  As a method for determining whether a Blu-ray disc is an SL type or a DL type, techniques such as those disclosed in Patent Documents 1 and 2 have been conventionally used (Note that Patent Documents 1 and 2 are used). Is about other optical discs, not Blu-ray discs).

That is, the objective lens is moved by a predetermined amount in the direction in which the objective lens is brought into contact with or separated from the Blu-ray disc (focus direction), and the number of peaks of the signal (reflected signal) indicating the amount of reflected light obtained at that time, or the number of focus S-shaped signals Count. If the number of signal peaks or S-shaped signals is two, it is determined as the SL type, and if the number of signal peaks or S-shaped signals is three, it is determined as the DL type. It should be noted that the number of signal peaks or S-shaped signals and the number of information recording layers do not coincide with each other even when the focal position of the objective lens matches the surface of the Blu-ray disc. This is because
JP 2007-141347 A JP 2002-367171 A

  However, in the Blu-ray disc, as shown in FIG. 5, the thickness of the cover layer covering the information recording layer is very thin (about 0.1 mm for the SL type, about 0.1 mm for the L0 layer and about 0 mm for the L1 layer for the DL type). 0.075 mm), and the difference in thickness between the DL type L0 layer and the L1 layer is small. For this reason, in the above-described conventional method, for example, where it should be determined as the DL type, the signal peaks are overlapped and cannot be separated well, and the number of signal peaks is erroneously determined as the SL type. There is.

  In the case of a BD-ROM, there is no distinction between the SL type and the DL type regarding the setting of the laser power of the laser diode (LD) that is the light source. There are few. However, in the case of BD-RE and BD-R, since the setting of the laser power of the LD differs between the SL type and the DL type, the influence of the failure to distinguish between the SL type and the DL type is large. Accurate discrimination is required.

  In view of the above points, an object of the present invention is to provide a method for discriminating an optical disc capable of accurately discriminating between an SL type and a DL type. Another object of the present invention is to provide an optical disc apparatus capable of executing such an optical disc discrimination method.

  In order to achieve the above object, the present invention is a method for discriminating the type of an optical disc by detecting the number of information recording layers of the optical disc. A step of focusing a light beam irradiating the optical disc on an information recording layer at a close position, a step of irradiating a predetermined region of the optical disc with the focused light beam, and a light beam on the predetermined region A step of determining whether or not a specific information region exists by irradiating; and a step of determining the number of the information recording layers based on the presence or absence of the specific information region. .

  According to this configuration, the number of information recording layers is determined by determining the presence or absence of a specific information area, and the information recording layer can be accurately recorded without failing to separate the signal peaks and by mistake in the number of information recording layers It is possible to determine the type of optical disc by determining the number of layers.

  According to the present invention, in the method for discriminating an optical disc having the above-described configuration, the presence or absence of the specific information area is determined based on the amount of reflected light obtained when the predetermined area is irradiated with a light beam. Also good. According to this, it is not necessary to read the recording information in the specific information area, and it can be easily determined whether or not the specific information area exists.

  In the optical disc discrimination method having the above-described configuration, the specific information area may be a BCA (Burst Cutting Area).

  In the optical disc identification method having the above-described configuration, the optical disc may be a BD-RE or a BD-R. In the BD-R and BD-RE standards, the BCA is formed only in the L0 layer. Therefore, according to the present invention, it is possible to determine whether BD-R and BD-RE are single layer (SL) optical discs or dual layer (DL) optical discs.

  In order to achieve the above object, the present invention comprises an optical pickup having an objective lens for condensing a light beam emitted from a light source on an information recording layer of the optical disc, and a discriminating means for discriminating the type of the optical disc. In the optical disc apparatus, the determination unit adjusts the focal position of the objective lens to the information recording layer located closest to the surface of the optical disc when viewed from the objective lens side, and the focal position of the objective lens , A process of moving the optical pickup to a predetermined area, a process of determining whether or not a specific information area exists by irradiating the predetermined area with a light beam, and the specific area And a process of determining the number of information recording layers depending on the presence or absence of an information area.

  According to this, when determining the number of information recording layers of the optical disc, it is determined based on the presence or absence of a specific information area, and it does not fail to separate the signal peaks and does not mistake the number of information recording layers. In addition, the number of information recording layers can be determined. In addition, since the type of the optical disk can be accurately determined, the reliability of the optical disk apparatus is improved.

  In the optical disk apparatus having the above-described configuration, the determination as to whether or not the specific information area exists may be performed based on the amount of reflected light obtained when the predetermined area is irradiated with a light beam. Good. According to this, it is not necessary to read the recording information in the specific information area, and it can be easily determined whether or not the specific information area exists.

  In the optical disc apparatus having the above-described configuration, the specific information area may be a BCA (Burst Cutting Area).

  In the optical disk device having the above-described configuration, the present invention may be configured such that the optical disk is a BD-RE or a BD-R. In the BD-R and BD-RE standards, the BCA is formed only in the L0 layer. Therefore, it is possible to determine whether the BD-R and the BD-RE are single layer (SL) optical discs or dual layer (DL) optical discs.

  According to the present invention, it is possible to provide an optical disc discrimination method capable of accurately discriminating between SL type and DL type for BD-RE or BD-R, for example. Further, according to the present invention, by applying such a determination method, for example, it is possible to accurately determine the SL type and the DL type for BD-RE or BD-R, and the reliability is improved. A high optical disc apparatus can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, embodiment shown here is an example of embodiment of this invention, and this invention is not the meaning limited to embodiment shown here. That is, various modifications can be made without departing from the object of the present invention.

  First, the configuration of the optical disc apparatus of the present embodiment will be described. FIG. 1 is a block diagram showing the configuration of the optical disc apparatus of the present embodiment. The optical disc apparatus 1 according to the present embodiment enables playback and recording of a Blu-ray disc (in principle, this term is used as an expression when BD-RE, BD-R, and BD-ROM are not particularly distinguished). Is provided. FIG. 1 shows, as an example, a state where a single layer (SL) type of a Blu-ray disc 50 is inserted in the apparatus.

  The spindle motor 2 is connected to a turntable 19 (see FIG. 2 described later), and can rotate the turntable 19. The turntable 19 holds the Blu-ray disc 50 so as to be detachable. Therefore, by rotating the spindle motor 2, the Blu-ray disc 50 held on the turntable 19 can be rotated.

  The optical pickup 3 is a device that irradiates the Blu-ray disc 50 with a light beam emitted from a light source, thereby enabling reading of information recorded on the Blu-ray disc 50 and writing of information to the Blu-ray disc 50. The configuration of the optical pickup 3 is the same as that of a known optical pickup, but will be briefly described with reference to FIG.

  FIG. 2 is a plan view for explaining the optical pickup 3 provided in the optical disc apparatus 1 of the present embodiment. In FIG. 2, the Blu-ray disc 50 is indicated by a broken line, but the Blu-ray disc 50 is positioned above the optical pickup 3 (a front side from the paper surface in a direction perpendicular to the paper surface). .

  The optical pickup 3 includes a laser diode (not shown) that emits a laser beam having a wavelength of 405 nm, and an information recording layer (L0 layer or L1 layer; see FIG. 5) of the Blu-ray disc 50 that emits the laser beam emitted from the laser diode. And an objective lens 21 that collects light and a photodetector (not shown) that receives the reflected light emitted from the laser diode and reflected by the information recording layer. The objective lens 21 is mounted on an actuator (not shown), and can be moved at least in the focus direction and the tracking direction by the action of the actuator.

  Note that the focus direction is a direction in contact with and away from the Blu-ray disc 50, and the tracking direction is a direction parallel to the radial direction of the Blu-ray disc.

  The optical pickup 3 is formed to slide along two guide rails 20 extending in the radial direction (direction parallel to the radial direction of the Blu-ray disc 50) by a drive mechanism (not shown). As a result, the optical pickup 3 can freely move in the radial direction and appropriately access any address of the Blu-ray disc 50.

  The drive mechanism for driving the optical pickup 3 includes, for example, a rack formed on the optical pickup 3, a slide motor, and a pinion rotated by the slide motor, and uses the relationship between the rack and the pinion. Move 3. The guide rail 20 is formed inside the optical disc apparatus 1.

  Returning to FIG. 1, the spindle motor drive circuit 4 controls the rotation of the spindle motor 2.

  The slide motor drive circuit 5 controls the drive of a slide motor provided as means for moving the optical pickup 3 in the radial direction. In the present embodiment, the slide motor is a stepping motor. For this reason, the slide motor drive circuit 5 can grasp the radial position of the optical pickup 3 based on the number of drive pulses.

  In order to detect the position of the optical pickup 3 based on the number of drive pulses, means for detecting the reference position of the optical pickup 3 is required. For example, a photo interrupter may be disposed.

  The RF amplifier 6 is supplied with an electrical signal from a photodetector (not shown) of the optical pickup 3 and generates a reproduction RF signal, a focus error signal (FE signal), a tracking error signal (TE signal), a reflection signal, and the like. . The generated reproduction RF signal is supplied to an equalizer 7 described later. The FE signal and the TE signal are supplied to a servo circuit 11 described later. Further, the FE signal and the reflected signal are supplied to the overall control unit 17 described later.

  The reflected signal is a signal indicating the signal intensity according to the amount of reflected light reflected by the Blu-ray disc 50, and is obtained as a sum signal obtained by summing the signals detected by the photodetector.

  The equalizer 7 performs equalization adjustment (waveform equalization processing) on the reproduction RF signal supplied from the RF amplifier 6. Here, equalization adjustment is a process of cutting off and boosting a component exceeding a certain frequency with respect to the reproduction RF signal.

  The clock extraction PLL circuit 8 is a synchronization signal generation circuit having a circuit configuration called PLL (Phase Locked Loop). The A / D converter 9 A / D-converts the equalized and adjusted reproduction RF signal in a form that matches the timing of the clock of the clock extraction PLL circuit 8.

  The decoder 10 receives the A / D converted signal, performs data demodulation processing and error correction processing, and outputs reproduced data.

  The servo circuit 11 generates a focusing drive signal and a tracking drive signal based on the FE signal and the TE signal. The generated focusing drive signal and tracking drive signal are sent to the actuator drive circuit 12.

  The actuator drive circuit 12 receives a focusing drive signal, a tracking drive signal, etc. from the servo circuit 11, and controls the drive of the actuator on which the objective lens 21 (see FIG. 2) is mounted. Further, the position of the objective lens 21 is also moved by a command from the overall control unit 17 described later.

  The encoder 13 receives recording data to be recorded on the Blu-ray disc 50 from the outside, and adds an error correcting code (ECC). The modulation circuit 14 encodes the data to which the error correction code is added according to a predetermined recording encoding method.

  When the signal encoded by the modulation circuit 14 is input, the recording compensation circuit 15 generates a recording pulse (recording pulse) according to a predetermined write strategy. The write strategy refers to a control rule for the recording pulse.

  The laser drive circuit 16 oscillates the laser diode of the optical pickup 3 according to the pulse waveform formed by the recording compensation circuit 15.

  The overall control unit 17 includes a microcomputer and is connected to each unit constituting the optical disc apparatus 1 and appropriately executes control processing according to an operation to be performed by each unit. Further, in the optical disc apparatus 1 of the present embodiment, the overall control unit 17 also functions as a discrimination unit that discriminates the detailed type of the Blu-ray disc 50 inserted in the optical disc apparatus 1. This point will be described later.

  The overall control unit 17 includes a memory 18. The memory 18 stores various parameters and operation programs necessary for the overall control unit 17 to perform various processes.

  Next, a method for discriminating the detailed type of the Blu-ray disc 50 inserted in the optical disc apparatus 1 will be described. The detailed type discrimination here is to first determine whether the Blu-ray disc 50 inserted into the apparatus is BD-RE, BD-R, or BD-ROM. Then, for each of them, it is determined whether the type is SL type or DL type.

  FIG. 3 and FIG. 4 are flowcharts showing a flow when discriminating detailed types of Blu-ray discs in the optical disc apparatus 1 of the present embodiment. Hereinafter, a description will be given with reference to FIGS.

  The detailed type of the Blu-ray disc 50 is determined, for example, when the Blu-ray disc 50 is inserted into the optical disc apparatus 1 or when the optical disc apparatus 1 is turned on. When the detailed determination of the Blu-ray disc 50 is started, the overall control unit 17 instructs the spindle motor drive circuit 4 to rotate the Blu-ray disc 50 (step S1).

  Next, the overall control unit 17 instructs the actuator drive circuit 12 to move the objective lens 21 to a predetermined position by moving the actuator (step S2). Specifically, the objective lens 21 is moved so that the focal position of the objective lens 21 is sufficiently in front of the disc surface of the Blu-ray disc 50.

  When the objective lens 21 is moved to a predetermined position, the overall control unit 17 instructs the laser drive circuit 16 to cause the laser diode of the optical pickup 3 to emit light with a predetermined laser power (step S3). Then, the overall control unit 17 instructs the actuator drive circuit 12 to start moving the objective lens 21 (step S4). The moving direction of the objective lens 21 at this time is a direction approaching the Blu-ray disc 50.

  At the same time when the movement of the objective lens 21 in step S4 is started (or just before the movement of the objective lens 21 in step S4 is started), the overall control unit 17 acquires a reflected signal from the RF amplifier 6. Is started (step S5). Thereafter, it is confirmed whether or not the objective lens 21 has moved a predetermined amount (step S6), and the movement of the objective lens 21 and acquisition of the reflection signal are continued until the objective lens 21 has moved a predetermined amount.

  In the present embodiment, the objective lens 21 is moved by a predetermined amount in the direction approaching the Blu-ray disc 50 to obtain the reflected signal, but the present invention is not limited to this. In other words, the objective lens 21 may be moved by a predetermined amount in the direction away from the Blu-ray disc 50 to acquire the reflected signal.

  When the objective lens 21 is moved by a predetermined amount, the overall control unit 17 determines whether or not the Blu-ray disc 50 is a BD-ROM based on the signal level of the obtained reflected signal (step S7). The determination as to whether or not it is a BD-ROM is made by comparing the threshold value stored in advance in the memory 18 with the obtained signal level.

  If it is determined that the type of the Blu-ray disc 50 is a BD-ROM, the overall control unit 17 further determines whether the BD-ROM is an SL type or a DL type (step S8). This determination is made based on the number of signal peaks of the reflected signal. That is, when the number of signal peaks of the reflected signal is two, it is determined as SL type, and when the number of signal peaks is three, it is determined as DL type. The signal peak of the reflected signal is obtained when the focal position of the objective lens 21 is aligned with the surface of the Blu-ray disc 50 and the information recording layer.

  As described above, in the Blu-ray disc 50, there is a possibility that the number of signal peaks of the reflected signal is wrong. However, in the BD-ROM, the setting of the laser power of the laser diode is not different between the SL type and the DL type, and the influence of the discrimination mistake at this stage does not become a big problem. The determination method is the same as the method.

  On the other hand, when it is determined that the Blu-ray disc 50 inserted in the optical disc apparatus 1 is not a BD-ROM, the overall control unit 17 determines whether or not the disc is a BD-R (Step S1). S9). Whether or not it is BD-R is determined by comparing the threshold value stored in advance in the memory 18 with the signal level of the obtained reflected signal, as in the case of BD-ROM.

  If it is determined in step S9 that it is not a BD-R, the overall control unit 17 determines that the Blu-ray disc 50 inserted in the optical disc apparatus 1 is a BD-RE (step S10). When it is determined that the Blu-ray disc 50 inserted into the optical disc apparatus 1 is BD-R or BD-RE, it is determined whether the Blu-ray disc 50 is an SL type or a DL type. Different from ROM.

  As described above, in BD-R and BD-RE, the setting of the laser power of the laser diode differs between the SL type and the DL type. This is because it is necessary to accurately determine whether it is a type. Hereinafter, a method for discriminating between the SL type and the DL type when it is determined as BD-R or BD-RE will be described with reference to FIG.

  When it is determined that the Blu-ray disc 50 inserted in the optical disc apparatus 1 is a BD-R or a BD-RE, the overall control unit 17 focuses on the information recording layer closest to the surface of the Blu-ray disc 50 to focus. Control is started (step S11). Specifically, when the objective lens 21 is moved from a predetermined position toward the Blu-ray disc 50 and the reflected signal and the focus error signal are observed while the reflected signal peak derived from the information recording layer first appears. The focus is pulled in and the focus control is started.

  When focus control is started, the overall control unit 17 issues a command to the slide motor drive circuit 5 to move the position of the optical pickup 3 to a predetermined position (step S12). Here, the predetermined position is a position where a BCA (Burst Cutting Area) 50a (see FIG. 2) may be formed in the Blu-ray disc 50, and from the center O (see FIG. 2) of the Blu-ray disc 50, Any position within a region having a distance of 21.3 to 22.0 mm.

  The BCA 50a is an area provided as a security measure against unauthorized copying, in which a barcode is recorded. The BCA 50a is provided in the vicinity of the innermost circumference of the Blu-ray disc 50. In the DL type Blu-ray disc 50, the L0 layer (light is irradiated) of the two information recording layers L0 and L1 (see FIG. 5). It is supposed to be provided only on the information recording layer existing on the back side as viewed from the side.

  In the BD-ROM, the BCA may not be provided. For this reason, the SL type and DL type discrimination methods described here cannot be applied to the BD-ROM.

  When the optical pickup 3 is moved to a predetermined position, next, the overall control unit 17 checks whether or not BCA exists (step S14). At this point, as described above, the laser beam irradiated from the optical pickup 3 to the Blu-ray disc 50 is in a state where the information recording layer near the disc surface (the surface near the optical pickup 3) is in focus. It has become. Further, as described above, the BCA is formed only in the L0 layer.

  For this reason, when the Blu-ray disc 50 inserted in the optical disc apparatus 1 is of the SL type, the light from the optical pickup 3 irradiates BCA, but in the case of the DL type, the optical pickup 3 Will irradiate a non-BCA area. When the light from the optical pickup 3 irradiates BCA and when it irradiates a non-BCA region, the amount of reflected light differs.

  Therefore, the reflected light is detected by the optical pickup 3 and a reflected signal is generated by the RF amplifier, and the light level from the optical pickup 3 is compared between the signal level and the threshold value recorded in advance in the memory 18. Can be determined whether or not BCA is irradiated. That is, it can be determined whether or not BCA exists.

  If it is determined by the confirmation of the existence of the BCA that the BCA exists, the overall control unit 17 determines that the Blu-ray disc 50 inserted in the optical disc apparatus 1 is the SL type (step S15). On the other hand, if it is determined that there is no BCA, the overall control unit 17 determines that the Blu-ray disc 50 inserted in the optical disc apparatus 1 is a DL type (step S15). As described above, when it is determined that the Blu-ray disc 50 inserted in the optical disc apparatus 1 is a BD-R or a BD-RE, it is reliably determined whether it is an SL type or a DL type. can do.

  As described above, in the optical disc apparatus 1 according to the present embodiment, the SL type and the DL type can be accurately determined for the BD-R and the BD-RE. And in this embodiment, it is the structure which judges based on the presence or absence of BCA based on the light quantity of reflected light instead of reading the content of the information recorded on BCA, and judging. For this reason, it is easy to realize a configuration for discriminating between the SL type and the DL type in the BD-R and BD-RE.

  In addition, in the embodiment described above, the case where the optical disc apparatus is an apparatus that records and reproduces a Blu-ray disc has been described. However, the present invention is not limited to this configuration. That is, it goes without saying that the present invention can be applied to an optical disc apparatus capable of recording and reproducing information with respect to a Blu-ray disc and at least one other type of optical disc.

  According to the present invention, for example, for BD-RE and BD-R, it is possible to accurately determine the SL type and the DL type. For this reason, the present invention is useful as a technique for discriminating optical disks.

These are block diagrams which show the structure of the optical disk apparatus of this embodiment. These are the top views for demonstrating the optical pick-up with which the optical disk apparatus of this embodiment is equipped. These are a part of flowcharts which show the flow at the time of discriminating the detailed kind of Blu-ray disc in the optical disc apparatus of this embodiment. These are a part of the flowcharts which show the flow at the time of discriminating the detailed kind of Blu-ray disc in the optical disc apparatus of this embodiment, and are flowcharts showing the continuation of FIG. These are explanatory drawings for explaining the configuration of a Blu-ray disc.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk apparatus 3 Optical pick-up 17 Whole control part (discriminating means)
21 Objective lens 50 Blu-ray Disc 50a BCA
L0, L1 information recording layer

Claims (8)

A method for determining the type of an optical disk by detecting the number of information recording layers of the optical disk,
Focusing the light beam applied to the optical disc on the information recording layer located closest to the surface of the optical disc when viewed from the side irradiated with the light beam;
Irradiating a predetermined region of the optical disc with a focused light beam;
Determining whether a specific information area exists by irradiating the predetermined area with a light beam; and
Determining the number of the information recording layers according to the presence or absence of the specific information area;
A discriminating method for an optical disc, comprising:   2. The method of discriminating an optical disk according to claim 1, wherein the presence or absence of the specific information area is determined based on the amount of reflected light obtained when the predetermined area is irradiated with a light beam.   The optical disc identification method according to claim 1 or 2, wherein the specific information area is a BCA (Burst Cutting Area).   4. The method according to claim 3, wherein the optical disk is a BD-RE or a BD-R. An optical disc device comprising: an optical pickup having an objective lens for condensing a light beam emitted from a light source on an information recording layer of the optical disc; and a discriminating means for discriminating the type of the optical disc,
The discrimination means includes
A process for adjusting the focal position of the objective lens to the information recording layer located closest to the surface of the optical disc as viewed from the objective lens side;
A process of moving the optical pickup to a predetermined area after adjusting the focal position of the objective lens;
A process of determining whether a specific information area exists by irradiating the predetermined area with a light beam;
A process of determining the number of the information recording layers according to the presence or absence of the specific information area;
An optical disc apparatus characterized by causing   6. The optical disc apparatus according to claim 5, wherein the determination of the presence or absence of the specific information area is performed based on the amount of reflected light obtained when the predetermined area is irradiated with a light beam.   7. The optical disc apparatus according to claim 5, wherein the specific information area is a BCA (Burst Cutting Area).   8. The optical disc apparatus according to claim 7, wherein the optical disc is a BD-RE or a BD-R.