JP4504269B2 - Information recording medium initialization method and initialization apparatus - Google Patents

Description

  The present invention relates to an initialization method and initialization apparatus for an information recording medium having a plurality of recording layers, and in particular, initialization can be easily performed by arbitrarily setting the defocus amount of each layer in a multilayer information recording medium. The present invention relates to an initialization method and an initialization apparatus.

  In recent years, as a rewritable large-capacity optical disk, a multi-layered phase change optical disk having two or more phase change recording films on one side of the optical disk has been devised. In the manufacturing process of the phase change optical disc, an initialization process is required to change the non-crystalline recording film immediately after the recording film is generated into a crystalline state.

  In this initialization process, a laser is used as a heat source to irradiate the disk surface with an elliptical initialization laser spot, and this laser spot is obtained at a predetermined laser spot scanning speed / laser power / laser spot at which a good crystal state is obtained. The entire surface of the optical disk is initialized by scanning the optical disk in a spiral manner with no defocus amount.

  The defocus amount of the laser spot is an amount by which the focal position is shifted with respect to the recording film without performing the just focus on the recording film in order to form the above-described elliptical initialization laser spot. As shown in FIG. 2, the focus control for a single-layer phase change optical disk according to the prior art is performed by irradiating a laser spot 15 from a semiconductor laser element onto an optical disk 14 having a single recording layer. The light passes through the objective lens 16 and the totsu lens 17 and is received by a plurality of detectors 18 and converted into electrical signals. The output signals from the detectors 18 are added and subtracted by an amplifier 19 to generate a focus signal, and an autofocus servo controller 21 feeds back a focus signal generated by the optical system and controls the laser spot 15 so that the irradiation diameter of the laser spot 15 on the optical disk 14 does not change, so that the laser spot follows the surface vibration and distortion of the optical disk 14. This is done by performing fifteen focus control.

  The defocus amount is controlled on the recording layer by focusing the laser spot on the incident light side or the back side of the disk without focusing the laser spot 15 on the recording layer of the disk 14. The shape of the laser spot is deformed into an oval shape, for example.

  The defocused state is generated by moving the position of the totsu lens 17 back and forth with respect to the incident light using a mechanical component such as a micrometer, so that the incident light incident on the detector 18 corresponds to the focal position of the laser spot 15. Take advantage of slipping.

  At this time, each focus signal when the focal position 22 of the laser spot is moved up and down around the recording layer will be described with reference to FIG. In FIG. 3, reference numeral 23 denotes a focus signal at the time of just focus that is not defocused / reference numeral 24 denotes a focal position of the focus signal at the time of just focus / reference numeral 25 denotes a focus signal / reference numeral 26 at the time of defocusing. When the focus position 26 of the focus signal when the defocus is applied, the focus position 26 in the defocus is shifted by the defocus amount (D) 29 with respect to the focus position 22 in the just focus.

  In the conventional autofocus control of the initialization device for the single-layer phase change optical disc, the feedback control is performed on the focal position 24 of the just focus in the case of just focus, and the focus position 26 of the defocus in the case of defocus. In contrast, feedback control is performed. In the case of just focus, this feedback control is performed so that the irradiation diameter of the laser spot 2 on the optical disc 1 does not change at the focus position 24 in the just focus, and in the case of defocus, the laser is at the focus position 26 in the defocus. Control is performed so that the irradiation diameter of the spot 2 on the optical disk 1 does not change.

  Accordingly, if the focus position 24 of the focus signal 23 generated when the defocus value is just focus is focused on the recording layer, the position of the lens when the recording layer is in focus is set as the incident light. On the other hand, by moving back and forth, the focus position 26 of the focus signal generated in the defocused state becomes a position 28 having a defocus amount 27 with respect to the recording layer which is a positional offset with respect to the recording layer. The position 28 at the time of defocus is a position where the focal point of the laser spot is offset from the recording layer to the incident light side or the back side of the disk, and the autofocus control is performed with respect to the focal point position 28 at this defocusing. Thus, focusing different from the case where the laser spot shape on the target recording layer is operated with just focus is performed, and initialization can be performed in a defocused state.

  However, defocus control for a phase change optical disc having a multilayer film has different optical characteristics and thermal characteristics for each recording layer, and different initialization conditions for obtaining good initialization for each layer. In order to initialize each layer of the optical disc having the plurality of recording layers in a single device, the initialization conditions on the device must be changed each time each layer is initialized.

  For example, in an apparatus capable of initializing an optical disc having a plurality of recording layers, by selecting the initialization target layer on the parameters, the recording target layer is separated using the focus signal from each layer, and the recording target layer is focused. Therefore, when initialization is performed under initialization conditions for obtaining good initialization for each layer, initialization parameters such as laser power and laser spot scanning speed are generally included in the initialization conditions. By changing the setting input conditions, it can be handled by microcomputer control.

The following patent documents are listed as documents describing the technology relating to the initialization of the phase change optical disk.
Japanese Patent Laid-Open No. 2004-13988

  As described above, an initialization apparatus that performs initialization for a single-layer phase-change optical disk can change the defocus amount setting condition. The defocus amount setting condition among the initialization conditions for the multi-layer phase change type optical disc is that the defocus amount is set and adjusted by mechanically changing the position of the lens inside the optical system to the disc recording film surface. It is necessary to shift the focal position of the laser beam to the focal point and change the shape and power density of the initialization laser spot irradiated on the film surface. In addition, there is a problem that it is difficult to set a defocus amount setting condition that provides good initialization characteristics for each recording layer.

  In order to solve the above problem, a method of initializing each recording layer using a plurality of initialization devices adjusted for the target recording layer, and a method of performing defocus by applying an electrical offset to the focus signal are also conceivable. However, the former has a problem that a plurality of initialization devices are required, and the latter has a small range of focus servo by applying an electrical offset, which is as small as ± several um, and a larger defocus can be applied. There was also a problem that it was impossible.

  An object of the present invention is to eliminate the above-described problems caused by the prior art, and it is easy to perform initialization by arbitrarily setting the defocus amount of each layer of a phase change type information recording medium having a plurality of recording layers. It is an object to provide an initialization method and initialization apparatus for a recording medium that can be used.

In order to achieve the above object, an invention according to claim 1 is an initialization apparatus for irradiating an optical disc having a plurality of recording layers with a laser spot to initially crystallize each recording layer, wherein the optical spot is applied to the optical disc. One objective lens to be irradiated, distribution means for distributing the reflected light reflected from the phase change optical disk via the objective lens, and the reflected light distributed by the distribution means are input, and the plurality of recording films A first optical system for generating a first focus signal for setting an arbitrary defocus amount by moving a focal point condensed on one of the recording surfaces in a normal direction of the recording surface, and distributed by the distributing unit A second focus is set by inputting the reflected light and moving the focus focused on the other recording surface of the plurality of recording films in the normal direction of the recording surface to set a defocus amount different from that of the first optical system. Generate focus signal A second optical system for a selector for selecting a focus signal from said first or second optical system, auto focus servo enter the focus signal selected by said selector to control the focusing of the laser spot Control means, and the autofocus servo control means inputs a focus signal from the optical system selected by the selector, and performs defocus control by the selected optical system based on the selected focus signal. the first means performs.

The invention according to claim 2 is an objective lens for irradiating a laser spot on an optical disk having a plurality of recording layers, and a distribution means for distributing reflected light reflected from the phase change optical disk via the objective lens; The reflected light distributed by the distributing means is input, and the focal point condensed on one recording surface of the plurality of recording films is moved in the normal direction of the recording surface to set an arbitrary defocus amount. The first optical system that generates one focus signal and the reflected light distributed by the distributing means are input, and the focal point that is focused on the other recording surface of the plurality of recording films is moved in the normal direction of the recording surface. A second optical system for generating a second focus signal for setting a defocus amount different from that of the first optical system, a selector for selecting a focus signal from the first or second optical system, Select by this selector And an autofocus servo control means for controlling the focusing of the laser spot by inputting the focused signal, and an initialization method of an initialization apparatus for irradiating the optical spot with the laser spot to initially crystallize each recording layer The auto focus servo control means inputs a focus signal from the optical system selected by the selector and performs defocus control by the selected optical system based on the selected focus signal. The second feature.

  An initialization apparatus and initialization method for a phase change optical disc having a plurality of recording layers according to the present invention includes an independent focus signal generation optical system having an arbitrarily movable defocus function corresponding to each recording target layer. As a result, it is possible to set favorable initialization conditions for each recording layer. The phase change type optical disc initialization apparatus and initialization method according to the present invention provides an independent focus signal generation optical system having an arbitrarily movable defocus function corresponding to each recording target layer. It is not necessary to move a mechanically movable part such as a lens position moving mechanism that causes a concern every time the initialization is performed, and high durability and high reliability can be ensured.

Hereinafter, an initialization apparatus and initialization method for a phase change optical disc having a plurality of recording layers according to an embodiment of the present invention will be described, and the principle of the present invention will be described.
<Principle explanation>
First, in general, in a phase change type optical disk having a plurality of recording layers, optical characteristics and thermal characteristics are different for each recording layer, and initialization conditions for obtaining good initialization characteristics are different.

  For this reason, an initialization apparatus capable of initializing a phase change optical disk having a plurality of recording layers can generally cope with this by changing parameter setting input conditions such as laser power and laser spot scanning speed. To set the focus amount, it is necessary to mechanically move the position of the lens.

  For this reason, when initializing each layer of a phase change optical disk having a plurality of recording layers with different defocus amount settings, the recording film is changed by mechanically changing the position of the lens every time the recording target layer is changed. Since the defocus amount can be changed by changing the focal position on the surface, a structure for moving the lens using a drive system mechanism such as a motor was examined.

  However, since this initialization apparatus is used in the optical disk manufacturing process, in the case of a phase change optical disk having n recording layers, the totsu lens is driven at least n times in the initialization process of one disk. We found the inconvenience that it was necessary and the durability and reliability of the mechanism part were lacking.

  For this reason, when initializing each recording layer of a phase change type optical disc having a plurality of recording layers with different defocus amount settings, the inventors have compared a phase change type optical disc having a multilayer structure with a plurality of phase change recording films. Thus, the present invention is constructed in which the optical system structures corresponding to the plurality of recording layers are assembled, and the optical system structures having the number corresponding to the plurality of recording layers are allocated to the respective recording layers.

  The optical system structure assigned to each recording layer has an independent focus signal generation optical system having a dedicated arbitrarily movable defocus function, and has good initialization characteristics for each recording layer. It is desirable to set the defocus amount condition to be set in advance.

  That is, the inventors, when initializing a desired recording layer from among a plurality of recording layers, outputs a control signal including information such as which recording layer among the plurality of recording layers is designated for initialization. A selector for switching the plurality of optical system structures is provided, and a focus signal of a desired recording layer is selected by selecting a focus signal of a designated recording layer from focus signals obtained from the optical detection system for each layer. On the other hand, an initialization apparatus and initialization method for a phase-change optical disc that performs focusing control with an optimum initialization condition for the recording layer have been invented.

Hereinafter, an embodiment of a recording medium initialization method and initialization apparatus according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a basic configuration of a recording medium initialization apparatus according to the present embodiment, FIG. 4 is a diagram for explaining an initialization operation of a first recording layer in the initialization apparatus, and FIG. FIG. 6 is a diagram for explaining the initialization operation of the second recording layer in the apparatus, and FIG. 6 is a diagram for explaining the continuous initialization operation of a plurality of recording layers in the initialization apparatus.
<Description of configuration>

  An initialization apparatus to which an initialization method for a phase change optical disc having a plurality of recording layers according to an embodiment of the present invention is applied is a double-layer disc in which the phase change optical disc has two recording layers as shown in FIG. In this case, a semiconductor laser element (not shown) that irradiates a laser spot 2 on a phase change optical disk 1 having two recording layers and a laser spot 2 focused on a recording target layer on the phase change optical disk 1. Therefore, the objective lens 3 that moves up and down in the optical axis direction, the half (mirror) BS4 that distributes the reflected light reflected from the recording layer to the optical system for each recording layer, and the first recording layer (L1) An optical system for the second recording layer (L2), an autofocus servo control unit 13 for performing autofocus servo of both optical systems, a selector 11 for switching between the two optical systems, selector And a microprocessor 12 for controlling the first switching other. The half BS4 corresponds to distribution means for distributing the reflected light.

  The optical system for the first recording layer (L1) is connected to the incident light distributed to the optical system for the first recording layer (L1) by the half BS4 using a micrometer or the like (phase) from the outside. A L1 layer totsu lens 5 whose position can be moved in the direction normal to the changeable optical disc surface, and a plurality of detectors 6 for detecting incident light from the first recording layer that has passed through the totsu lens 5; The amplifier 7 generates a focus signal by adding and subtracting output signals from the plurality of detectors 6.

  The optical system for the second recording layer (L2) is front and rear (phase change type optical disc) from the outside with a micrometer or the like with respect to incident light distributed to the optical system for the second recording layer by the half BS4. A totsu lens 8 whose position can be moved in the direction normal to the surface), a plurality of detectors 9 for detecting incident light from the first recording layer that has passed through the totsu lens 8, and a plurality of detectors 9 And an amplifier 10 that generates a focus signal by performing addition and subtraction on the output signal.

The selector 11 switches the focus signal A output from the optical system for the first recording layer and the focus signal B output from the optical system for the second recording layer, thereby switching the focus from the microprocessor 12. The focus signal is selected according to the designation of the control target layer. The autofocus servo control unit 13 feedback-inputs a focus signal generated from one of the recording layer optical systems selected by the selector 11, and the irradiation diameter of the laser spot 2 on the optical disc 1 changes. By controlling so that the laser spot 2 does not move, the focus control of the laser spot 2 is performed following the surface vibration and distortion of the optical disc 1.
<Description of operation>

  Next, when initializing the first recording layer, the initialization apparatus for a phase change optical disk having two recording layers configured as described above, in response to an instruction from the microprocessor 12, as shown in FIG. When the selector 11 selects the first optical system, the focus signal A from the optical system for the first recording layer is fed back to the autofocus servo unit 13, and the autofocus servo unit 13 makes the optical spot 1 of the laser spot. By controlling the objective lens 3 in the vertical direction so that the irradiation diameter does not change, the focus control of the laser spot is performed following the surface vibration and distortion of the optical disk.

  At this time, the laser spot 2a required for initialization is moved by moving the tote lens 5 which can move back and forth with respect to the incident light for the first recording layer to a position where an optimum defocus value is set for the first recording layer. The shape and power density can be set. The defocus amount adjustment value for the first recording layer and the defocus amount (D) 33 for the recording layer that is a positional offset with respect to the first recording layer are in a proportional relationship.

  Next, in the initialization apparatus, when the second recording layer is initialized, the selector 11 selects the second optical system in accordance with an instruction from the microprocessor 12 as shown in FIG. The focus signal B from the optical system is fed back to the autofocus servo unit 13, and the autofocus servo unit 13 controls the objective lens 3 in the vertical direction so that the irradiation diameter of the laser spot on the optical disk 1 does not change. Thus, the focus control of the laser spot is performed following the surface deflection and distortion of the optical disk.

  At this time, by moving the lens 8 that can move back and forth with respect to the incident light for the second recording layer to a position where an optimum defocus value is set for the second recording layer, the laser spot necessary for initialization is moved. The shape and power density can be set. The defocus amount adjustment value for the second recording layer and the defocus amount (D) 45 for the recording layer that is a positional offset with respect to the second recording layer are in a proportional relationship.

  As described above, the initialization apparatus according to the present embodiment includes a plurality of optical systems (movable lens / detector / amplifier) corresponding to a plurality of recording layers, a half BS that distributes reflected light to both optical systems, A selector that switches the output to the autofocus servo section of both optical systems is provided, and the initialization of each layer of the multi-layer phase change optical disc is performed by switching the selector or adjusting the position of the appropriate defocus amount of the totsu lens. It can be carried out.

  The autofocus control in the initialization operation for this multilayer phase change optical disc will be described with reference to FIG. FIG. 6 shows a focus signal from the optical system for each recording layer, a focus position, and an initialization operation for each layer when each layer of a phase change optical disc having two recording layers is continuously initialized with different defocus amount settings. It is a figure for demonstrating the relationship of the focus control signal used for feedback control at the time of execution.

In this autofocus control, feedback control is performed with the second recording layer (L2) shown in the lower part of FIG. 6 being defocused, and then the first recording layer (L1) shown in the upper part. Will be described assuming that feedback control is performed in a just-focus state.
The initialization apparatus according to the present embodiment, when the focal position 56 of the laser spot is moved from the back side to the near side centering on the recording layer, the focus signal 57 from the first recording layer optical system in the middle of FIG. The focus signal 58 from the optical system for the second recording layer is detected.

  The initialization apparatus selects the focus signal detected by the optical system for the first recording layer during the first recording and the focus signal detected by the optical system for the second recording layer during the second recording. The focus signal 59 for feedback control can be generated by switching and inputting to the autofocus servo control unit 13.

  The initialization apparatus according to the present embodiment performs feedback control on the true focal position 63 of the first recording layer when initializing the first layer, and performs the second control when initializing the second layer. Feedback control is performed by using a focus signal 58 from the recording layer optical system as a focusing servo center 64 at a position where the defocus amount (D) 65 is shifted from the true focal position 62 of the second recording layer to the true focal position. Thus, it is possible to initialize a phase change optical disk having a plurality of recording layers with one initialization apparatus with initialization spots having different defocus amounts. In the case of this structure, if a defocus amount suitable for each recording layer is set in advance, it is not necessary to move the lens every time the recording layer is initialized, so a mechanical drive mechanism is not provided. Therefore, a highly reliable and highly durable initialization device can be configured.

  As described above, the initialization apparatus and method according to the present embodiment have an optical system as many as the number of recording target layers when initializing each layer of a phase change optical disc having a plurality of recording layers with different defocus amount settings. A multi-layer phase change optical disk can be initialized by a single device by disposing a totsu lens that can move back and forth with respect to incident light for each optical system for each recording layer and switching the optical system. .

In the embodiment, the example in which each layer of the same type of phase change optical disc having a plurality of recording layers is initialized with different defocus amount settings has been described, but the present invention is not limited to this. For example, by utilizing the fact that different defocus values can be set in each of a plurality of optical systems, various phase change optical disks having different defocus values suitable for initialization / phase change optical disks not having a plurality of recording layers On the other hand, it is also possible to initialize a variety of phase-change optical disks on the same line using a single initialization device.
Specifically, when CD-RW discs and DVD-RW discs having different defocus setting values are initialized, the type of disc to be sent to the line of the initialization device is, for example, CD-RW disc → DVD. Each time a change is made to the value of the defocus meter mechanically every time it is changed to -RW or from a DVD-RW disc to a CD-RW, each of a plurality of defocus setting values as in the present invention is set. By providing the optical system, the defocus value can be changed simply by selecting the target optical system using parameters.

1 is a diagram illustrating a basic configuration of an initialization apparatus for a multilayer recording medium according to an embodiment. Explanatory drawing of the defocus control at the time of initializing the recording medium of a single layer. The figure which shows each focus signal etc. in the recording medium of a single layer. Explanatory drawing of the initialization operation | movement of the 1st recording layer in this initialization apparatus. Explanatory drawing of the initialization operation | movement of the 2nd recording layer in this initialization apparatus. Explanatory diagram of continuous initialization operation for multiple recording layers in this initialization device

Explanation of symbols

1: phase change optical disk, 2: laser spot, 3: objective lens, 5: totsu lens, 6: detector, 7: amplifier, 8: totsu lens, 9: detector, 10: amplifier, 11: selector, 12: microprocessor, 13: Autofocus servo control unit, 14: Optical disc, 15: Laser spot, 16: Objective lens, 17: Totsu lens, 18: Detector, 19: Amplifier, 21: Autofocus servo control unit, 22: Focus position, 23: Focus Signal: 24: Focus position, 26: Focus position, 27: Defocus amount, 28: Focus position, 56: Focus position, 57: Focus signal, 58: Focus signal, 59: Focus signal for feedback control, 62: Focus Position, 63: Focus position, 64: Focusing servo center.

Claims (2)

An initialization apparatus for irradiating an optical disc having a plurality of recording layers with a laser spot to initially crystallize each recording layer, the objective lens for irradiating the optical spot with a laser spot, and a phase through the objective lens Distributing means for distributing the reflected light reflected from the changeable optical disc, and the reflected light distributed by the distributing means are input, and the focal point condensed on one recording surface of the plurality of recording films is focused on the recording surface. A first optical system that generates a first focus signal that moves in a normal direction and sets an arbitrary defocus amount, and the reflected light distributed by the distributing means are input, and the other of the plurality of recording films is input. a second optical system for generating a second focus signal for setting the different defocus amounts and by moving the focal point that is focused on the recording surface in a direction normal to the recording surface of the first optical system, the first or the second optical system A selector for selecting a focus signal et, enter the focus signal selected by the selector and a automatic focusing servo control means for controlling the focusing of the laser spot, the autofocus servo control means, by said selector An initialization apparatus that receives a focus signal from a selected optical system and performs defocus control by the selected optical system based on the selected focus signal . One objective lens that irradiates a laser spot onto an optical disk having a plurality of recording layers, a distribution means that distributes reflected light reflected from the phase-change optical disk via the objective lens, and the above-mentioned distributed by the distribution means A first focus signal is generated by inputting reflected light and generating a first focus signal for setting an arbitrary defocus amount by moving a focus focused on one recording surface of the plurality of recording films in a normal direction of the recording surface. An optical system and the reflected light distributed by the distributing means are input, and a focal point focused on the other recording surface of the plurality of recording films is moved in the normal direction of the recording surface to move the first optical system A second optical system that generates a second focus signal that sets a defocus amount different from the above, a selector that selects a focus signal from the first or second optical system, and a focus signal selected by the selector The Auto-focus servo control means for controlling the focusing of the laser spot by force, and an initialization method for an initialization apparatus for initial crystallization of each recording layer by irradiating the optical disc with the laser spot, The initialization is characterized in that the focus servo control means inputs a focus signal from the optical system selected by the selector and performs defocus control by the selected optical system based on the selected focus signal Method.

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