JP2006114158A - Optical disk of multilayer structure and its recording layer identification method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk of multilayer structure whose recording layer can quickly be identified with a simple circuit composition, and also provide its recording layer identification method. <P>SOLUTION: An optical disk is provided with a plurality of recording layers (10 and 20). In addition, grooves (12 and 22) and lands (14 and 24) adjacent to the grooves (12 and 22) are formed on the recording layers (10 and 20), respectively, and land prepit groups (16 and 26) including a plurality of land prepits (18 and 28), respectively, are formed on lands (14 and 24), respectively. The numbers of the land prepits (18 and 28) constituting the land prepit groups (16 and 26) are equal in the land prepit groups (16 and 26) formed on one of the recording layers (10 and 20) but are different from each other between the land prepit groups (18 and 28) formed on the other recording layer (10 and 20). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present application relates to a multilayer structure optical disc and a recording layer identification method of the optical disc, and more particularly to a multilayer structure optical disc including at least two recording layers and a recording layer identification method of the optical disc.

  Currently, in order to achieve an increase in capacity of an optical disc, an optical disc in which two recording layers are laminated has been proposed. In this type of optical disc, when recording / reproducing information, it is necessary to set various parameters such as the power of a light beam used for recording / reproduction in accordance with each recording layer. For this reason, each recording layer is identified. Need arises. Therefore, the first recording layer and the second recording layer of the optical disc are provided with identification formats for identifying the first recording layer and the second recording layer, respectively. Whether the layer is the first recording layer or the second recording layer is identified. Thus, in the conventional recording layer identification method, it is necessary to read the identification format provided in the recording layer, so that there is a problem that it takes time to identify the recording layer.

  As a prior art, there is an optical disk recording layer identification method described in Patent Document 1.

  In the recording layer identification method of this publication, the first layer track and the second layer track are formed as the two recording layers of the optical disc, the first layer track and the second layer track are both wobbled, and the phase of the wobble is The phase changes and the amount of phase change is set to be different for each recording layer. Accordingly, it is possible to identify whether the track of the recording layer is the first layer track or the second layer track by detecting the phase change amount of the wobble applied to the track of each recording layer.

JP 2002-279647 A

  As another prior art, there is an optical disk recording layer identification method described in Patent Document 2.

  In the recording layer identification method of this publication, a first address mark and a second address mark are arranged on the first recording layer and the second recording layer of an optical disc having a two-layer structure, respectively. The first recording layer and the second recording layer are identified based on the difference in address mark pattern in the signal.

JP 2000-29389A

  In the recording layer identification method described in the publication of the above-mentioned Patent Document 1, when detecting the phase change amount of the wobble applied to the track of each recording layer, the wobble signal of each track is detected and the phase change of the wobble is detected. The amount needs to be determined. As described above, since it takes time to detect the wobble signal of each track and determine the phase change amount of the wobble, there is a problem that it takes a long time to identify the recording layer.

  Further, in the recording layer identification method described in the above-mentioned publication, the reproduction signal is obtained from the optical disc, and the first layer track and the second layer track are identified based on the difference in the address mark pattern in the reproduction signal. To do. Thus, since it takes time to obtain a reproduction signal from an optical disk and to obtain a difference in address mark pattern in the reproduction signal, there is a problem that it takes a long time to identify a recording layer.

  Further, in the case of a recordable disc such as a DVD-R disc in which an RF signal such as an address mark cannot be obtained when it is not recorded, there is a problem that the recording layer cannot be determined when it is not recorded.

  The problem to be solved by the present application includes the above-described problem as an example.

  The invention described in claim 1 is provided with a plurality of recording layers, and each recording layer is formed with a groove and a land adjacent to the groove, and each land has a plurality of lands. An optical disc in which land pre-pit groups each including pre-pits are formed, and the number of land pre-pits constituting each land pre-pit group is formed in one recording layer The land pre-pit groups are the same, and the land pre-pit groups formed in different recording layers are different from each other.

  A second aspect of the present invention is a recording layer identification method for mutually identifying the recording layers formed in the optical disc according to the first aspect, from the land prepit group in each of the recording layers. Presence / absence of the land prepits corresponding to the difference in the number of land prepits between the land prepit groups formed in different recording layers based on push-pull signals obtained based on the reflected light of Based on the above, the recording layers are distinguished from each other.

  A third aspect of the present invention is a recording layer identifying device for mutually identifying the recording layers formed in the optical disc according to the first aspect, wherein the recording layers are identified from the land prepit groups in the respective recording layers. The land prepits corresponding to the difference in the number of land prepits between the land prepit groups formed in different recording layers based on the push-pull signal obtained by receiving the reflected light of It is characterized by comprising detection means for detecting presence / absence and identification means for mutually identifying the recording layers based on the detected presence / absence.

  Next, the best mode for carrying out the present application will be described with reference to the drawings.

  FIG. 1 shows an optical disc according to an embodiment of the present application, FIG. 1 (A) shows a first recording layer of the optical disc, and FIG. 1 (B) shows a second recording layer of the optical disc.

  In FIG. 1A, the first recording layer 10 of the optical disk has a groove 12 and lands 14 and 14 adjacent to both sides of the groove 12. A land pre-pit group 16 is intermittently formed on one land 14 of the lands 14 on both sides of the groove 12.

  Here, in the first recording layer 10, the number of prepits 18 constituting the land prepit group 16 is three. Next, in FIG. 1B, the second recording layer 20 of the optical disc has a groove 22 and lands 24 and 24 adjacent to both sides of the groove 22. A land pre-pit group 26 is intermittently formed on one land 24 of the lands 24 on both sides of the groove 22. Here, in the second recording layer 20, unlike the case of the first recording layer 10, since the fourth prepit for identifying the recording layer is added, the number of prepits 28 constituting the land prepit group 26 is as follows. Four.

  Thus, in the first recording layer 10 and the second recording layer 20, the number of prepits 18 and 28 constituting the land prepit groups 16 and 26 is set to 3 and 4, respectively. Therefore, the first recording layer 10 and the second recording layer 20 can be identified by detecting the presence or absence of the fourth pit of the pre-pit groups 16 and 26 of the recording layers 10 and 20. Therefore, the recording layers 10 and 20 can be identified by a simple configuration in which the presence or absence of the fourth pit of the pre-pit groups 16 and 26 of the recording layers 10 and 20 is detected.

  1A and 1B, an arrow A indicates the radial direction of the optical disc, and an arrow B indicates the traveling direction of the light beam irradiated on the optical disc.

  FIG. 2 shows an apparatus to which a recording layer identification method for identifying a recording layer of an optical disc according to an embodiment of the present application is applied.

  In FIG. 2, a turntable 34 is attached to a drive shaft 32 of a spindle motor 30, and an optical disk 36 is placed on the turntable 34. An optical pickup 38 is disposed below the optical disk 36. The optical pickup 38 irradiates the optical disk 36 with a light beam, and supplies an output signal 40 to the signal processing circuit 41 based on the reflected light beam from the optical disk 36. To do.

  FIG. 3 shows details of the optical pickup and the signal processing circuit in the apparatus of FIG.

  Referring to FIGS. 2 and 3, the optical pickup 38 includes an irradiation unit (not shown) that irradiates the optical disk 36 with a light beam, and a photodetector 39 that receives the reflected light beam from the optical disk 36. The photodetector 39 is a four-divided photodetector, that is, the photodetector 39 is composed of four detector sections 42, 44, 46, and 48. In FIG. 3, an arrow C indicates the radial direction of the optical disk, and a symbol D indicates the traveling direction of the light beam spot 54 irradiated on the optical disk. The light beam spot 54 is set so as to irradiate the groove of the recording layer of the optical disk and two lands adjacent to both sides of the groove. That is, in the case of the first recording layer 10 in FIG. 1A, the light beam spot 54 is set so as to irradiate the groove 12 and the lands 14 on both sides thereof. In the case of the second recording layer 20), the groove 22 and the lands 24, 24 on both sides thereof are set to be irradiated.

  In FIG. 3, output signals 56, 58, 60, and 62 are output from the four detector sections 42, 44, 46, and 48 of the photodetector 39, respectively, and these four output signals 56, 58, 60, 2 and 62 are collectively shown as one output signal 40 in FIG. The signal processing circuit 41 includes three adders 64, 66 and 68 and one subtractor 70, and output signals 56 and 60 from the detector units 42 and 46 are supplied to the adder 64. The output signals 58 and 62 from the detector sections 44 and 48 are supplied to an adder 66. Output signals 72 and 74 from the adders 64 and 66 are supplied to an adder 68 and a subtractor 70, and an RF signal 76 from the adder 68 is supplied to various circuits (not shown). Further, the servo signal from the subtracter 70, that is, the push-pull signal 78 is used to identify the recording layer of the optical disc, as will be described later.

  FIG. 4 shows a waveform of an output signal from the signal processing circuit of FIG. 3 when a DVD-R (unrecorded) having a two-layer structure is used as an optical disc, that is, a signal waveform at the time of tracking servo close. . 4A shows the waveform of the RF signal, and FIGS. 4B and 4C show the waveform of the push-pull signal. That is, FIG. 4B shows the first recording layer of the optical disc. FIG. 4C shows the waveform of the push-pull signal based on the second recording layer of the optical disc.

  First, when the DVD-R having a two-layer structure is not recorded, as shown in FIG. 4A, the RF signal 76 from the signal processing circuit 41 is sent to the first recording layer and the second recording layer of the optical disc. Therefore, the first recording layer and the second recording layer cannot be identified based on the RF signal 76.

  Next, considering the push-pull signal 78 from the signal processing circuit 41, as shown in FIGS. 1A and 1B, the land prepit group 16 of the first recording layer 10 of the optical disk is configured. The number of prepits 18 is three, while the number of prepits 28 constituting the land prepit group 26 of the second recording layer 20 of the optical disc is four. Therefore, as shown in FIG. 4B, the push-pull signal 78 based on the first recording layer of the optical disc has three peaks 80, 80, and 80 corresponding to the three prepits. 4C, the push-pull signal 78 based on the second recording layer of the optical disc has four peaks 82, 82, 82, and 82 corresponding to the four prepits. Thus, in the waveform of FIG. 4B, since the peak corresponding to the fourth bit is not detected, the recording layer corresponding to the waveform is identified as the first recording layer, while FIG. In the waveform of C), since a peak corresponding to the fourth bit is detected, the recording layer corresponding to the waveform is identified as the second recording layer.

  In order to obtain the peak of the waveform of the push-pull signal 78 based on the pre-pits 18 and 28 constituting the land pre-pit groups 16 and 26 of the recording layers 10 and 20 of the optical disc, the amplitude of the push-pull signal 78 is set to a predetermined value. By comparing with the threshold value S (see FIGS. 4B and 4C), the peak of the waveform of the push-pull signal 78 can be quickly obtained with a simple configuration.

  Next, FIG. 5 shows the assignment of land prepits in the optical disc according to the embodiment of the present application, and FIG. 5A shows the assignment of three land prepits in the first recording layer. (B) shows the allocation of four land prepits in the second recording layer.

  In FIG. 5A, b2 to b0 of the first recording layer and b3 to b1 of the second recording layer in FIG. Although 1b and prepit data = 0b have the same pattern, as shown in FIG. 5B, the layer recording bit b0 is set in the second recording layer.

  In the case of an optical disc having a two-layer structure, a combination of three bits of b2 to b0 of the first recording layer in FIG. 5A and b3 to b1 of the second recording layer in FIG. And “1”. Therefore, the fourth bit for recording layer identification is set for the first recording layer and the second recording layer, and based on the presence or absence of the fourth bit for identifying the recording layer, that is, “1” or “0”. Thus, the first recording layer and the second recording layer can be identified. That is, in the embodiment of the present application, as shown in FIG. 5B, in the second recording layer, the fourth bit for recording layer identification is always set to “1”, while FIG. ), In the first recording layer, the fourth bit for recording layer identification is always set to “0”, and the fourth bit for identification of the recording layer is “1”. The first recording layer and the second recording layer can be identified based on whether they are “0” or “0”.

  As described above, in the embodiment of the present application, since the recording layer is identified based on the presence or absence of the recording layer identification land prepit of each recording layer, the address data recorded in the land prepit is decoded. Compared with the case where the recording layer is identified, the recording layer can be quickly identified with a simple circuit configuration. That is, when decoding the address data recorded in the land pre-pits, it takes a long time by a complicated circuit to decode the address data based on the RF signal. In the embodiment, the amplitude of the push-pull signal is compared with a predetermined threshold, the presence / absence of a land pre-pit for recording layer identification is detected, and the recording layer is identified based on the detection signal. It is possible to quickly identify the recording layer.

FIG. 1A shows a first recording layer of an optical disc, and FIG. 1B shows a second recording layer of an optical disc according to an embodiment of the present application. 1 shows an apparatus to which a recording layer identification method for identifying a recording layer of an optical disc according to an embodiment of the present application is applied. FIG. 3 is a circuit diagram showing details of an optical pickup and a signal processing circuit in the apparatus of FIG. 2. FIG. 4A is a waveform diagram of an output signal from the signal processing circuit of FIG. 3 when a dual-layer DVD-R (unrecorded) is used as an optical disc, and FIG. (B) shows the waveform of the push-pull signal based on the first recording layer of the optical disc, and FIG. 4 (C) shows the waveform of the push-pull signal based on the second recording layer of the optical disc. FIG. 5A shows the allocation of three land prepits in the first recording layer, and FIG. 5B shows the allocation of 4 land prepits in the optical disc according to the embodiment of the present application. The assignment of one land pre-pit is shown.

Explanation of symbols

10 First Recording Layer 12 Groove 14 Land 16 Land Prepit Group 18 Land Prepit 20 Second Recording Layer 22 Groove 24 Land 26 Land Prepit Group 28 Land Prepit 38 Optical Pickup 39 Photodetector 41 Signal Processing Circuit

Claims (3)

A land pre-pit comprising a plurality of recording layers, each recording layer having a groove and a land adjacent to the groove, and each land including a plurality of land pre-pits. An optical disc in which groups are formed respectively,
The number of the land prepits constituting each of the land prepit groups is the same in the land prepit groups formed in one recording layer, and the land prepit groups are formed in different recording layers. An optical disc characterized in that it differs between land pre-pit groups. A recording layer identification method for mutually identifying the recording layers formed in the optical disc according to claim 1,
The number of land prepits between the land prepit groups formed in different recording layers based on push-pull signals obtained based on the reflected light from the land prepit groups in each recording layer A recording layer identification method, wherein the recording layers are identified from each other based on the presence or absence of the land prepits corresponding to the difference. A recording layer identification device for mutually identifying the recording layers formed in the optical disc according to claim 1,
Based on the push-pull signal obtained by receiving the reflected light from the land pre-pit groups in each recording layer, the land pre-pits between the land pre-pit groups formed in different recording layers Detecting means for detecting the presence or absence of the land prepits corresponding to the difference in number;
Identification means for mutually identifying the recording layers based on the detected presence or absence;
A recording layer identification device comprising:

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