JP2005327327A - Multilayer optical information medium and manufacturing method for multilayer optical information medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information recording method for a multilayer optical medium by which accessibility of a multilayer optical information medium is enhanced and smooth data transfer and enhancement of random access properties are made possible as a result and to provide an information medium and a recording and reproducing device. <P>SOLUTION: The multilayer optical information medium is characterized in that natural frequency (Fb) and another variable frequency component (Fv) are imparted to each layer of the multilayer information medium, the device performing recording and/or reproduction with respect to the medium acquires layer information by detecting the frequencies imparted to individual information layers of the medium and deciphering the frequency characteristics. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an information information medium, an optical information recording method, and an information recording medium device, and more particularly to a high-density optical information recording method having a plurality of information layers.

  In recent years, not only computer information but also information such as voice, still images, and moving images has been digitized, and the amount of information handled has become extremely large. Along with this, it is necessary to increase the capacity of optical information media for storing such information. With respect to such an optical information medium, CD-R and CD-RW that perform recording / reproduction with a laser beam having a wavelength of about 780 nm have spread worldwide, and recently, recording / reproduction is performed with a laser beam having a wavelength of about 650 nm. Signs of widespread use of recordable DVDs such as DVD-R and DVD-RAM have appeared. More recently, the wavelength of the laser light source has been shortened to near 400 nm, and the numerical aperture (NA) of the objective lens is made 0.6 or more, thereby reducing the diameter of the spot focused on the optical disk surface. A new standard was developed to increase the density, and in March 2003, it was put into practical use as a Blu-ray recorder and released.

By the way, as a method of dramatically increasing the capacity of the optical information medium so far, the laser light wavelength (λ) is shortened, the numerical aperture (NA) of the objective lens is increased, and the laser light of the medium is transmitted. Techniques such as reducing the recording / reproducing laser spot diameter (laser wavelength / NA) by reducing the thickness of the light transmission layer have been performed. However, the shortening of the wavelength of the laser for recording / reproducing is approaching the limit, and it is actually the case that the recording material is becoming difficult to form the minimum mark by the technology based on the conventional heat mode recording.
For this reason, attempts have been made to increase the capacity of optical information media by methods other than conventional approaches in various fields. For example, multi-value recording, volume recording using a hologram instead of a flat surface of a disk, and a multilayer information medium having a plurality of information layers on one optical information medium. In particular, the multi-layer information medium is the most practical technology because there are relatively few changes from the conventional DVD technology compared to other methods, and as a multi-layer technology that exceeds two layers on one side of the current DVD, for example, non-patent It is reported in literature 1 etc.

International Symposium on Optical Memory 2003 Technical Digest PP10-11, Optical Data Storage Topical Meeting 2003 Technical Digest

However, of course, the recording / reproducing speed of these large-capacity information media must not be sacrificed in exchange for the increase in recording capacity. This is because if the recording / playback speed is slower than before, the infrastructure built on the basis of the conventional data transfer speed, such as image quality, smoothness of moving images, contents, etc., cannot be used and becomes impractical. Because. Even in a multilayer information medium, even if the transfer speed of continuous data is the same as the prior art, in order to access an arbitrary layer, it is necessary to repeat focusing → tracking → address reading as before. It takes a lot of time loss. Therefore, it takes more time than the conventional system performance. Although there have been patents on correct layer selection in the prior art, there are no proposals that take this into account.
The present invention has been made to solve such a technical problem, and its object is to improve the accessibility of a multilayer optical information medium, and to enable smooth data transfer and random accessibility. The present invention provides an information recording method, an information medium, and a recording / reproducing apparatus related to a multilayer optical medium.

  For this purpose, an apparatus for recording and / or reproducing the medium by giving a specific frequency (Fb) and another variable frequency component (Fv) to each layer of the multilayer information medium is provided. Layer information is obtained by detecting the frequency given to each information layer and decoding its frequency characteristic.

  In the information recording method to which the present invention is applied, if layer information is displayed at a variable frequency (Fv) / reference frequency (Fb), for example, in a multilayer optical information medium having three or more information layers , Focusing-> Tracking-> Address reading-> Focusing on another layer-> Resolving the problem of reading layer information while repeating, etc. Information recording that enables accurate and quick access even in multilayer information media A method can be provided.

In the information recording method to which the present invention is applied, if the optical information medium is formed with a plurality of information layers or reproduction signal layers, for example, the CD size considered as one of the next generation optical information medium technologies Thus, an optical information information medium that is particularly effective for a large capacity optical information medium of 200 GB / sheet and that requires quick access and does not require time for access is provided.

The structure of the optical information medium according to the present invention will be specifically described below with reference to FIG. As a method for creating a multilayer information medium exemplified in the following examples, a known general method can be adopted. For example, a phase change medium such as JP 2002-074742 or a conventional ROM medium (for example, International It can also be applied to Symposium on Optical Memory 2003 Technical Digest PP10-11).

In FIG. 1, 1 indicates the entire information medium, 2 indicates a selected layer (unit) in the information medium 1, and 3 indicates a guide groove or mark row having address information.
As a method for providing the information medium 1 with a frequency having layer information, one is a method using a meandering frequency of the guide groove 3 formed on the recording layer. The main purpose of the wobble frequency is to display the media information and the address of the data to be recorded. By demodulating the information obtained from the wobble frequency assigned to the groove (recording groove), the information Is read and addressing is performed. When the layer 2 is selected based on the meandering frequency of the guide groove according to this method, the meandering frequency of the conventional guide groove for address information is fixed for the purpose of address display that the meandering of the guide groove has conventionally. It is desirable. Therefore, it is considered that the best method is to calculate by comparing with the wobble frequency by adding another frequency component. Since the measured value varies depending on the rotation speed of the medium at the absolute frequency, it should be calculated by the ratio of the meandering frequency of the guide groove. Further, adding a meandering frequency component of the guide groove for increasing the number of layers or selecting the exact layer 11 does not disturb the gist of the present invention.
In a ROM medium consisting of only mark rows, meander frequency can be formed by meandering the mark rows, but the S / N ratio is lowered. Therefore, it is possible to provide a frequency area by forming a groove dedicated to reading layer information. After completing the access to the target playback layer by reading the frequency components formed in each playback layer of the layer information medium in accordance with the format common to only a specific area, any arbitrary content in the same playback layer It is possible to perform track jump to the data area for quick data access.
As another method of applying a frequency, there is a method using a frequency by repeating a recording mark-gap. Unlike the wobble frequency, it is impossible to apply frequency components to the entire area of the medium. However, a mark-gap sequence containing frequency components is formed in the specific area, for example, the innermost part to select the layer 2 By doing so, it is possible to read a frequency with a high S / N ratio. Further, this method has a great merit in a recordable medium. This will be described in detail below.
For example, when a 10-layer multilayer recording medium 1 is created, if the data format has layer information as a data string, 10 types of masters must be prepared. The yield of a high-density information medium master is extremely poor, and even if one of the 10 masters is NG, all completed recording media are NG.
However, if the method according to the present invention is employed, it is possible to form multiple layers in the same format. A single master can be restored to an infinite number of masters by transfer or grandchild transfer, so productivity is extremely high. In addition, the manufacturing process can be greatly simplified. The completed multi-layer information recording medium can perform quick data access when used by a user by applying pre-write containing layer information in a specific area for each layer by a recording device capable of fine layer selection. In addition, it may be performed by the recording device owned by the user after distribution to the user, even during the manufacturing process, to apply the prelight containing the layer information in a specific area for each layer. Ideally, pre-write is performed as part of the manufacturing process before shipment.
Further, in a ROM medium composed only of mark rows, it is possible to provide a frequency detection area by forming a mark dedicated to reading layer information. Arbitrary ones in the same playback layer after completing access to the target playback layer by reading the frequency components that are formed in each playback layer of the layer information medium only by following a common format in a specific area It is possible to perform track jump to the data area and to perform quick data access.
As a method of discriminating the reference frequency (Fb) and the variable frequency (Fv) among the plurality of detected frequency components, the absolute value of the frequency as shown in FIG. 2 is measured, and the layer from the variable frequency component (Fv) is measured. Selection information can be detected. However, in order to measure the absolute frequency, the number of rotations of the optical information medium must be set accurately. Therefore, for example, when it is assumed that the relationship of Fb <Fv is always satisfied (or Fb> Fv), a reference frequency (Fb) such as Fv / Fb, Fb / Fv, Δ (Fv−Fb) / Fb, and a variable frequency ( A method of calculating by the ratio of Fv) is a more desirable form. By doing as described above, it is possible to detect the layer selection information from the frequency measurement without setting an accurate rotation speed of the medium.
As another method of distinguishing the reference frequency (Fb) and the variable frequency (Fv) from the detected frequency components, the frequency component intensities of the reference frequency (Fb) and the variable frequency (Fv), that is, C / N (or The layer selection information can be detected from the frequency measurement by the method of calculating by the ratio of (S / N). This is especially effective for the frequency display using the repeat mark-gap described above.

In addition, the drive needs to have a structure in which focusing movement in the thickness direction is easy, and it is desirable to have a mechanism for reading the frequency of the information layer only by focusing without tracking, but the S / N ratio of frequency reading It is obvious that the time required for access can be greatly shortened by simply reading the layer information while repeating focusing → tracking → focusing → tracking → focusing → tracking →. is there.
The reader according to the present invention must have a mechanism for detecting the frequency. Specifically, when performing the layer selection method based on the meandering frequency of the guide groove described above, it has a mechanism capable of measuring the meandering frequency of the guide groove, and when detecting based on the intensity ratio of the frequency described above, As shown in FIG. 2, it is necessary to have a mechanism for measuring C / N or S / N. Further, in the case of performing layer selection based on the mark-gap repetition frequency, the frequency component and C / N can be detected by using the RF signal detection mechanism of the recording / reproducing apparatus as it is.
In particular, when layer selection is performed based on the repetition frequency of the latter mark-gap, detection is possible not only by the frequency but also by the C / N dB ratio. However, accurate C / N measurement requires the number of samplings, and it takes time, so it is desirable to make a simple determination based on only the carrier component dB.

Schematic diagram showing a multilayer optical information medium in the present invention The schematic diagram which shows the measurement result of the frequency component of the multilayer optical information medium in this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multilayer optical information medium 2 The layer (unit) selected in the multilayer optical information medium 1
3 Guide grooves with address information or mark rows

Claims (7)

In a multilayer optical information medium having a plurality of information layers in one medium,
Each information layer is given a unique frequency and a variable frequency component consisting of at least one frequency component, and an apparatus for recording and / or reproducing the medium uses the frequency assigned to each information layer of the medium. A multilayer optical information medium characterized in that layer information is obtained by detecting and decoding a unique frequency and a variable frequency component assigned to each information layer. 2. The layer information is displayed and detected based on a variable frequency / reference frequency or a Δ variable frequency / reference frequency based on a unique frequency and a variable frequency component assigned to each information layer. Multi-layer optical information medium The unique frequency and variable frequency component assigned to each information layer displays and detects layer information based on the difference or ratio of the C / N or S / N intensity between the variable frequency and the reference frequency. The multilayer optical information medium according to claim 1 or 2. An apparatus for recording and / or reproducing the medium in which the inherent frequency and variable frequency component given to each information layer is formed by the meandering frequency of the guide groove formed in each information layer. The meandering frequency of the guide groove is detected only by focusing the laser on the substrate, and the layer information is obtained by decoding the inherent frequency and variable frequency component given to each information layer. The multilayer optical information medium according to any one of claims 1 to 3. A unique frequency given to each information layer and a variable frequency component are formed by a repetitive mark-gap sequence in which the frequency is formed at a specific portion of each information layer, and the medium is recorded and / or reproduced. The device that performs the above-described detection of the frequency formed by the repeated mark-gap sequence by only focusing the laser on the substrate, and decodes the unique frequency and variable frequency component assigned to each information layer. 4. The multilayer optical information medium according to claim 1, wherein layer information is obtained by In a multilayer information medium having a plurality of information layers in one medium, a specific frequency component not provided in the other layers is given to the layer closest to the laser beam incident side for signal reading and / or the farthest layer. The multilayer optical information medium according to claim 1. In a method for manufacturing a recordable multilayer optical information medium comprising at least two information layers, after completion of the layering process of information layers created in the same format, pre-write with frequency components is applied to record or reproduce information. A method of manufacturing a multilayer optical information medium, wherein optical layer information can be acquired by acquiring a frequency component or signal intensity pre-written at the time only by focusing on a laser substrate.

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