JP2009093748A - Device and method for bca recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent BCA recording in the outer recording layer of an optical disk having multiple recording layers. <P>SOLUTION: The device for performing BCA recording in an optical disk including multiple recording layers where laser beam irradiation exceeding predetermined laser power causes saturation of reflectance is provided with a laser head 25a for irradiating an optical disk 6 with a laser beam, a focus control circuit 14 for performing focus control on an optional recording layer, a BCA data buffer 18 for storing a BCA signal, and a control circuit for controlling BCA recording by irradiating a laser spot 9 with light from the laser head 25a. BCA data stored in a BCA data buffer 18 is recorded in the inner recording layer in the focused state of the laser spot 9 in the inner recording layer of the optical disk, and the outer recording layer is irradiated with a laser beam by laser power where reflectance of the outer recording layer is uniformly saturated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a BCA recording apparatus and a BCA recording method capable of recording BCA for the purpose of copyright protection and copy protection on a recording medium of a multi-layer recording format. The present invention relates to a BCA recording apparatus and a BCA recording method capable of forming BCA in a recording layer.

  Currently, some of the DVD media that are in widespread use are bar code-like physics that are completely different from pits (marks) that contain content data (music / video, etc.) on the optical disk recording surface or reflective film surface. The mark is recorded. The bar-code-like physical marks are arranged in the circumferential direction on the inner circumference side of the optical disc and are called BCA (Burst Cutting Area) and include unique information such as disc information and disc ID.

  The BCA is formed by a laser beam after forming a laminated film such as a reflection film or a recording film in the optical disc manufacturing process, and records arbitrary marks (data) using a special apparatus such as a BCA recording apparatus. It is very difficult for a user to make a copy. On the other hand, DVD-RAM and DVD-RW are commercialized as rewritable DVDs (registered trademarks), and phase change materials are used as recording materials for these recording media. The crystallized state is changed by irradiating the laser pod with the laser pod, and information is recorded / reproduced by utilizing the change in reflectance caused by the change in the crystallized state.

As a document describing a technique related to a method and an apparatus for recording BCA on this phase change type optical disk, for example, the following Patent Document 1 is cited, and this patent document includes a double-layer recording layer of a two-layer optical disk. It is described that BCA is recorded by irradiating a semiconductor laser to each.
JP 2007-73122 A

  HDDVD-R and BD-R, which are recordable optical discs released in recent years, have two recording layers, and the BCA of these two-layer discs is located on the recording layer at the back as viewed from the laser incident surface. It is standardized to record the BCA mark. Therefore, when recording BCA on these write-once dual-layer discs, the BCA recording apparatus forms a BCA by focusing the laser spot on the recording layer on the back side and irradiating this laser beam with the spot.

  In BCA recording of such recent recordable dual-layer discs (HDDVD-R, BD-R), in addition to the fact that the interlayer distance is narrower than that of the conventional dual-layer DVD, the aforementioned recording layer on the back side is used. When the laser spot is focused on, the laser spot used for BCA recording has a relatively large power density and area as compared with the spot used for data recording / reproduction, so that the sensitivity of the recording film also in the recording layer on the front side. Depending on the case, there may be a problem that the BCA mark is recorded. The recognition of the BCA is identified by the amplitude of the reproduction signal based on the difference in reflectance between the recording mark of the BCA portion and the space portion.

  An object of the present invention is to provide a BCA recording apparatus and a BCA recording method capable of preventing a BCA mark from being recorded on a recording film on the medium surface side of a write-once type dual-layer disc in view of the above-mentioned problems caused by the prior art. is there.

  In order to achieve the above object, the present invention provides a recording in which a recording layer whose reflectance is reversibly changed by laser light irradiation at a predetermined power level and whose reflectance is saturated by laser light irradiation exceeding the predetermined laser power is formed in multiple layers. A BCA recording apparatus that records BCA on a medium, a laser head that irradiates the recording medium with laser light of an arbitrary shape, a focus control circuit that performs focus control of the laser light on an arbitrary recording layer of the recording medium, A BCA data buffer for storing the BCA signal for BCA recording, and a control circuit for controlling BCA recording by irradiating a laser beam from the laser head to the recording medium, the control circuit being controlled by the focus control circuit B stored in the BCA data buffer in the recording layer on the inner layer side with the focal point of the laser beam focused on the recording layer on the inner layer side of the recording medium Performs BCA recording using the A signal, the reflectivity of the outer layer-side recording layer in the recording layer of the outer layer is the first feature to make a laser beam irradiation by the laser power to be saturated.

  According to the present invention, in the BCA recording apparatus having the above characteristics, the control circuit causes the focus control circuit to focus the laser beam on the recording layer on the inner layer side of the recording medium, and the first process. A second step of recording the BCA by irradiating the recording medium with the laser beam using the BCA signal stored in the BCA data buffer in a state where the focal point is maintained by the focus control circuit, and the focus control circuit after the second step. A third step of focusing on the recording layer on the outer layer side of the recording medium, and a laser with a laser power at which the reflectance of the outer recording layer is saturated in the outer recording layer while maintaining the focusing point The second feature is that the fourth step of performing light irradiation is performed.

  According to the present invention, in the BCA recording apparatus having the characteristics described above, the wavelength of the laser beam irradiated by the laser head is 405 nm, the spot width in the disk circumferential direction of the laser spot is 1 μm, and the spot length in the disk radial direction is 10 μm. A third characteristic is that the power is 300 to 500 mW.

  Furthermore, the present invention stores a laser head that irradiates a recording medium with laser light having an arbitrary shape, a focus control circuit that performs focus control of the laser light on an arbitrary recording layer of the recording medium, and a BCA signal for BCA recording. A BCA recording method for a BCA recording apparatus, comprising: a BCA data buffer; and a control circuit for controlling BCA recording by irradiating a recording medium with laser light from the laser head, wherein the control circuit is controlled by the focus control circuit. Performing BCA recording on a recording layer on the inner layer side using the BCA signal stored in the BCA data buffer in a state in which the focal point of the laser beam is focused on the recording layer on the inner layer side of the recording medium; And a step of irradiating the recording layer with laser light with a laser power at which the reflectance of the outer recording layer is saturated.

  According to the present invention, in the BCA recording method having the above characteristics, the control circuit causes the focus control circuit to focus the laser beam on the recording layer on the inner layer side of the recording medium, and the first process. A second step of recording the BCA by irradiating the recording medium with the laser beam using the BCA signal stored in the BCA data buffer in a state where the focal point is maintained by the focus control circuit, and the focus control circuit after the second step. A third step of focusing on the recording layer on the outer layer side of the recording medium, and a laser with a laser power at which the reflectance of the outer recording layer is saturated in the outer recording layer while maintaining the focusing point The fifth feature is that the fourth step of performing light irradiation is performed.

  According to the present invention, in the BCA recording method of the above feature, the control circuit sets the wavelength of the laser beam irradiated by the laser head to 405 nm, the spot width in the disk circumferential direction of the laser spot, and the spot length in the disk radial direction. The sixth characteristic is that the thickness is 10 μm and the laser power is 300 to 500 mW.

  In the BCA recording apparatus and the BCA recording method according to the present invention, the laser beam is focused on the inner recording layer of the recording medium by the focus control circuit and stored in the inner recording layer in the BCA data buffer. BCA recording is performed using the BCA signal, and the BCA mark is recorded on the outer recording layer by setting the outer recording layer to a laser power at which the reflectance of the outer recording layer is saturated. Can be prevented.

Hereinafter, an embodiment of a BCA recording apparatus to which a BCA recording method according to the present invention is applied will be described in detail with reference to the drawings. FIG. 1 is a diagram for explaining a BCA recording layer of a two-layer write-once optical disc that is an object of the present invention, FIG. 2 is a diagram for explaining a BCA recording method of a write-once optical disc, and FIG. FIG. 4 is a diagram for explaining an example of conventional BCA recording of the Low to High type, and FIG. 5 is a diagram of BCA recording according to the present embodiment of the Low to High type. FIG. 6 is a diagram for explaining an example, FIG. 6 is a diagram for explaining the operation of the BCA recording method according to the present embodiment, and FIG. 7 is a diagram showing the configuration of the BCA recording apparatus according to the present embodiment.
[Description of configuration]

  There are various types of DVD-R, HDDVD-R, and BD-R as the dual-layer write-once optical disc that is the subject of this embodiment, and the configuration of these optical discs is shown in FIG. When the two-layer write-once optical disc 6 is arranged with the first recording layer 1 disposed on the front side and the second recording layer 2 disposed on the rear side as viewed from the reproduction surface, the DVD-R Is standardized to record BCA on the first recording layer, record the second recording layer BCA for HD DVD-R, and record the second recording layer BCA for BD-R. .

  Further, as a method of recording data and BCA on the various optical disks, a laser beam (laser spot) shaped into a predetermined shape is irradiated to a state where the recording film after film formation has a relatively high reflectance, and the irradiation is performed. By reforming the part with low reflectivity, recording is performed in a high-to-low (High to Low) recording method, and the recording film after film formation is shaped into a predetermined shape with respect to a relatively low reflectivity. There is a system called a low to high recording system in which recording is performed by irradiating the irradiated laser beam (laser spot) and modifying the irradiated part to a high reflectance. Note that organic dyes are generally used for the Low to High recording medium, and when the irradiation laser power is higher than the laser power required for BCA recording, the reflectance of the recording layer material is saturated. There is a tendency to change (modify) substantially uniformly.

  These recording methods will be described with reference to FIG. 2. In the high-to-low recording method, a recording laser output is output in a narrow pulse shape with respect to a film surface having a high reflectance after film formation. A low-reflectance bar-shaped recording mark is formed in the background of the film, and the Low to High recording method uses a recording laser output on a film surface having a low reflectance after film formation to provide a space (background) portion other than the BCA mark. By setting a high reflectance, a bar-shaped recording mark having a low reflectance is formed in the background having a high reflectance. The optical disk reproducing apparatus optically detects the difference in reflectance between the bar-shaped recording mark and the space portion to obtain a BCA reproduction signal.

  As shown in FIG. 7, the BCA recording apparatus that performs the BCA recording receives a semiconductor laser 6a that emits a laser beam having an output power of a predetermined wavelength, a laser beam emitted from the semiconductor laser 6a, and enters the disk radial direction. A spot forming optical system 10 for forming a laser spot 9 having an arbitrary shape (perfect circle or long shape) toward the head, and an objective lens 7b for strongly narrowing the laser beam 28 formed by the spot forming optical system 10; A two-layer separation recognition optical system 13 that recognizes the two recording layers 1 and 2 separately and generates a focus servo signal corresponding to each recording layer, and an objective lens so as not to cause a focus shift with respect to a disc surface shake The two-layer focus control circuit 14 that performs focusing control by moving 7b in the direction 7a and the optical disk 6 are rotated in the direction 78 (reference numeral 15a) at a predetermined rotational speed. The spindle motor 15 to be rotated, the rotary encoder 16 for detecting the rotation angle of the disk according to the rotation of the motor 15, and the modulation clock signal based on the rotation angle detected by the encoder 16 in synchronization with the rotation angle of the disk. The generated clock synchronization circuit 17, the modulation circuit 19 for generating a signal 32 for recording on the disk surface based on the buffer data for BCA recording stored in the data buffer 18 and the modulation clock signal, and the semiconductor laser 6a A laser driver circuit 22 for driving the light source, a carriage 25 for moving the spot 9 focused on the disk recording layer in the disk radial direction 36, and each circuit of the focus system / laser system / motor system / carriage system and the overall operation of the apparatus. And a microprocessor (hereinafter referred to as MPU) 26. The semiconductor laser 6a / spot forming optical system 10 / double-layer separation recognition optical system 13 and the objective lens 7 constitute a laser head 25a.

  When the laser spot formed on each layer of the optical disc is focused on the second recording layer on the back side, the laser spot for data recording / reproducing is focused on the second recording layer 1 as shown in FIG. A small circular spot A is formed, but the first recording layer 1 is also irradiated with a large circular spot B having a radius ΔL larger by defocused (blurred) laser light. Similarly, the laser spot for BCA recording forms a long and long spot A ′ that is advantageous for shortening the tact time on the second recording layer 2, but the long and long spot A ′ is also formed on the first recording layer 1. A large elongated spot B ′ having a width and a length that is larger by ΔL than the elongated spot is irradiated. ΔL can be expressed as ΔL = Lm × (arcsin (NA / Lm refractive index)), where Lm is the dimension between the first and second recording layers and NA is the numerical aperture.

  Here, the degree of defocus (blurring) in the first recording layer is compared between the circular laser spot for data recording / reproducing and the oval spot for BCA recording when focused on the second recording layer on the back side. In this case, as shown in FIG. 3, it can be seen that the oval spot is smaller in blurring (spot area in the first recording layer / spot area in the second recording layer). In other words, the oval spot used in the BCA recording apparatus tends to have a relatively high power density (not attenuated) on the first recording layer.

  For this reason, for example, in BCA recording on a Low to High disc, as shown in FIG. 4, although the BCA is recorded with focusing on the second recording layer on the back side, it is also recorded on the first recording layer side. There are cases where the BCA mark is recorded. As a result, a large reproduction signal (change in reflectance between the mark portion and the space portion) appears also from the first recording layer where BCA should not be recorded, and this causes a problem when the reproduction apparatus reproduces the BCA signal. It will occur.

  Here, in the BCA recording method on the Low to High disc according to the present embodiment, the laser spot 25 is moved to the BCA recording start position of the double-layer optical disc 6 and the two-layer separation recognition optical system 13 is used. 2 In a state where BCA recording is focused on the recording layer 2, the defocusing light applied to the first recording layer 1 is operated so as to perform BCA recording as a laser power that can saturate the reflectance of the recording layer. .

  In this BCA recording, a BCA mark is formed by irradiating a laser beam on a rotating disk to form a BCA mark. At this time, the laser spot given to the second recording layer 2 of the optical disk is a focused small spot. Therefore, the reflectance of only the irradiated portion is saturated according to the pulse emission to form the BCA mark, and the defocused laser spot given to the first recording layer 1 is enlarged by ΔL as shown in FIG. In order to provide a high laser power in a range, as shown in FIG. 5, a mark signal having a slightly narrow width remains in the BCA signal portion from the first recording layer 1 but is reformed over most of the BCA signal. The signal 50 is large in the second recording layer 2 and can be small enough to be ignored in the first recording layer 1.

  The laser used in this embodiment has a wavelength of 405 nm, which is the same as that used for recording / reproduction of the optical disc, the spot width in the disc circumferential direction of the laser spot is 1 μm, and the spot length in the disc radial direction is 10 μm. In this case, it is desirable to use a laser output having a power of 300 to 400 mW or more.

  Next, the operation of the BCA recording apparatus for the low-to-high disk by another method according to the present embodiment will be described with reference to the flowchart of FIG. Step S01 for moving the laser head 25a to the BCA recording start position of the double-layer optical disc 6; Step S02 for focusing on the second recording layer 2 using the two-layer separation recognition optical system 13; Step S03 of performing BCA recording on the second recording layer 2 of the optical disc 6 by driving the laser driver circuit 22 while modulating the BCA previously recorded in 18 by the modulation circuit 19, and determining whether or not it is the BCA recording end position. When it is determined that the end position has not been reached, step S04 is returned to step S03. In the double-layer optical disc 6 at this time, the recording marks similar to the mark recording recorded on the second recording layer 2 are recorded on the first recording layer as described above.

  In the BCA recording apparatus according to the present embodiment, following step S05 shown in FIG. 6, the step S06 of moving the laser spot 9 to the BCA recording start position of the double-layer optical disc 6 and the double-layer separation recognition optical Step S07 for focusing on the first recording layer 1 using the system 13, step S08 for supplying a DC laser power for driving the laser driver circuit 22 to saturate the first recording layer 1 of the optical disc 6, and erasing ( Saturation) It is determined whether or not the target BCA recording end position is reached. When it is determined that the end position has not been reached, step S09 returns to step S08, and when it is determined that the process has ended in step S09, the erasure process is stopped. By executing step S10, the first recording recorded when the BCA recording is performed on the second recording layer described above. It operates to erase the recording marks of the layer 1 BCA.

  As described above, when performing BCA recording on the second recording layer of the low-to-high optical disc, the BCA recording apparatus and method according to the present embodiment records the BCA on the second recording layer and then performs the first recording. By focusing on the layer and saturating the reflectance of the first recording layer, unnecessary BCA marks recorded on the first recording layer can be erased. In the above embodiment, the example in which the first recording layer is saturated after recording the BCA on the second recording layer has been described, but this order may be reversed.

  As described above, the BCA recording apparatus and method according to the present embodiment uses the laser power that saturates the first recording layer while focusing on the second recording layer 2 during the BCA recording in the low-to-high method. By performing BCA recording on the recording layer 2, it is possible to prevent the BCA mark from remaining in the first recording layer on the near side. Further, after recording the BCA in a state where the second recording layer is focused on, the BCA mark is placed on the near side by irradiating the first recording layer with a DC power at which the reflectivity of the first recording layer is saturated. It is possible to prevent remaining in the first recording layer. In the above embodiment, a two-layer recording medium has been described as an example, but the present invention can also be applied to a multilayer recording medium.

The figure for demonstrating the BCA recording layer of the double layer film write-once optical disk used as the object of this invention. The figure for demonstrating the BCA recording method of a write-once optical disk. The figure for demonstrating the laser spot shape on each recording surface of a two-layer type optical disk. The figure for demonstrating the conventional BCA recording example of a low to high type. The figure for demonstrating the example of BCA recording by this embodiment of low to high type. The figure for demonstrating operation | movement of the BCA recording method by this embodiment. 1 is a diagram illustrating a configuration of a BCA recording apparatus according to an embodiment.

Explanation of symbols

  1: recording layer, 2: recording layer, 6: two-layer write-once optical disc, 6a: semiconductor laser, 7: objective lens, 9: laser spot, 10: spot forming optical system, 13: two-layer separation recognition optical system, 14 : Two-layer focus control circuit, 15: spindle motor, 16: rotary encoder, 17: clock synchronization circuit, 18: data buffer, 19: modulation circuit, 22: laser driver circuit, 25: carriage, 25a: laser head.

Claims (6)

A BCA recording apparatus that records BCA on a recording medium in which a reflectance is reversibly changed by laser beam irradiation at a predetermined power level and a recording layer that is saturated by laser beam irradiation exceeding the predetermined laser power is formed.
A laser head that irradiates a recording medium with laser light of an arbitrary shape;
A focus control circuit that performs focus control of the laser beam on an arbitrary recording layer of the recording medium;
A BCA data buffer for storing the BCA signal for BCA recording;
A control circuit for controlling BCA recording by irradiating a recording medium with laser light from the laser head,
The control circuit is
While the focus control circuit focuses the laser beam on the inner recording layer of the recording medium, BCA recording is performed on the inner recording layer using the BCA signal stored in the BCA data buffer. ,
A BCA recording apparatus that irradiates the outer recording layer with laser light at a laser power at which the reflectance of the outer recording layer is saturated. The control circuit comprises:
A first step of focusing the laser beam on the inner recording layer of the recording medium by the focus control circuit;
A second step of recording the BCA by irradiating the recording medium with a laser beam using the BCA signal stored in the BCA data buffer while maintaining the focal point in the first step;
A third step of focusing the laser beam on the recording layer on the outer layer side of the recording medium by the focus control circuit after the second step;
The BCA recording apparatus according to claim 1, wherein a fourth step is performed in which the outer recording layer is irradiated with laser light with a laser power at which the reflectance of the outer recording layer is saturated while maintaining the focal point.   3. The laser power is 300 to 500 mW, wherein the wavelength of the laser beam emitted from the laser head is 405 nm, the spot width of the laser spot in the disk circumferential direction is 1 μm, the spot length in the disk radial direction is 10 μm. BCA recorder. A laser head that irradiates a recording medium with laser light of an arbitrary shape, a focus control circuit that performs focus control of the laser light on an arbitrary recording layer of the recording medium, a BCA data buffer that stores a BCA signal for BCA recording, A BCA recording method of a BCA recording apparatus comprising: a control circuit that controls BCA recording by irradiating a recording medium with laser light from the laser head;
The control circuit is
BCA recording using the BCA signal stored in the BCA data buffer on the inner recording layer while the focus control circuit focuses the laser beam on the inner recording layer of the recording medium. When,
And a step of irradiating the outer recording layer with a laser beam with a laser power at which the reflectance of the outer recording layer is saturated. The control circuit comprises:
A first step of focusing the laser beam on the inner recording layer of the recording medium by the focus control circuit;
A second step of recording the BCA by irradiating the recording medium with a laser beam using the BCA signal stored in the BCA data buffer while maintaining the focal point in the first step;
A third step of focusing the laser beam on the recording layer on the outer layer side of the recording medium by the focus control circuit after the second step;
5. The BCA recording method according to claim 4, wherein a fourth step is performed in which the outer recording layer is irradiated with laser light with a laser power at which the reflectance of the outer recording layer is saturated while maintaining the focal point.   The control circuit has a laser beam wavelength of 405 nm, a laser spot spot width in the disk circumferential direction of 1 μm, a disk radial spot length of 10 μm, and a laser power of 300 to 500 mW. The BCA recording method according to 3 or 4.

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