JP2009015878A - Multilayer optical disk and optical disk apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure stability against the layer-to-layer distance differences in each multilayer optical disk and against layer-to-layer distance fluctuations caused by problems in the fabrication of the disks. <P>SOLUTION: A multilayer optical disk preliminarily stores layer-to-layer distance information in a control track. The layer-to-layer distance information from the control track is read and a setting value adapted to the layer-to-layer distance information is set in a prescribed circuit. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical disc and an optical disc apparatus having a multilayer structure, and an object thereof is to stabilize the operation of the optical disc apparatus during recording and reproduction of the multilayer optical disc.

As an approach to increasing the density of optical discs, there is a multilayered recording / reproducing surface. The details of the technology relating to the multilayering are disclosed in Patent Document 1, and as a commercially available multilayered optical disc, Although it has a two-layer structure, a Blu-ray disc (hereinafter referred to as BD) is known.
Japanese National Patent Publication No. 10-505188 Japanese Patent Laid-Open No. 10-143872

  In a multilayer structure of a multilayer optical disc, there are cases where the interlayer distance between the recording / reproducing surfaces is different for three reasons. The first is to prevent reflected light and transmitted light across a plurality of recording / reproducing surfaces during recording / reproducing from interfering with each other on the recording / reproducing surface to be recorded / reproduced. If the variation in interlayer distance due to the performance of the manufacturing process operated by each manufacturer cannot be converged within a certain range, allow multiple manufacturers to determine the interlayer distance for each. In addition, there are cases where the design value of each interlayer distance itself has a large aspect that depends on the specific technical level of each manufacturer, and in this case as well, when determining the interlayer distance for a plurality of manufacturers. Must be allowed to be arbitrary.

  Therefore, under the circumstances as described above, the following problems are caused.

  That is, in order to switch the recording / reproducing surface, an interlayer focus jump means for forcibly moving the position of the objective lens equipped in the optical pickup for recording / reproducing signals to within the focal depth of the recording / reproducing surface is used. However, under the above-described circumstances, the moving distance of the objective lens during the interlayer focus jump operation differs for each jump operation, and the movement (jump) from one recording / reproducing surface to another recording / reproducing surface is performed. Immediately before, this means that the moving distance is unknown.

  Therefore, the movement of the objective lens from a certain recording / reproducing surface to a desired recording / reproducing surface is an interlayer focus jump operation in an optical disk having a two-layer structure, that is, a movement from the first recording / reproducing surface to the second recording / reproducing surface. It must be said that it will be extremely difficult.

  Therefore, in Patent Document 2, even if the moving distance from one recording / reproducing surface to another recording / reproducing surface is unknown, an interlayer distance detecting means is provided, and an interlayer focus jump operation is performed based on the detection result of the interlayer distance detecting means. A method for guaranteeing an interlayer focus jump operation by controlling the setting of the jump pulse generating means is disclosed.

  However, since the interlayer focus jump operation is performed in relation to the focus servo, the addition of the interlayer distance detection means described above further complicates the configuration of the focus servo, and the focus servo system including the interlayer distance detection means It requires additional time for verification and evaluation of validity, and causes an overall increase in cost.

  In addition, the recording / reproducing operation of an arbitrary recording / reproducing surface of the multilayer optical disc must naturally take into account the correction of spherical aberration. Under the above-described circumstances, the spherical aberration correcting means for the desired recording / reproducing surface may be used. It can be said that the set value of the operating point is unknown.

  Therefore, in the case of a spherical aberration correction means for driving a spherical aberration correction element such as a liquid crystal by setting the operating point (voltage level), it is necessary to obtain the desired operating point using another means. In general, the realization of such an operating point detection means needs to deal with a large spherical aberration dependent on the total distance of a plurality of interlayer distances, so that the spherical aberration correction including the operating point detection means is included. It requires additional time for verification and evaluation of the validity of the means, and causes an overall increase in cost.

  In order to solve the above-described conventional problems, the multilayer optical disc of the present invention is characterized in that interlayer distance information as a design value of the multilayer optical disc is recorded in advance in a control track area assigned to the multilayer optical disc. To do.

  The multilayer optical disc according to the present invention is characterized in that interlayer distance information of the multilayer optical disc is recorded in advance in a BCA (Burst Cutting Area) area assigned to a predetermined area of the multilayer optical disc.

  The multilayer optical disc of the present invention is characterized in that a measured value of the interlayer distance of the multilayer optical disc measured by a predetermined method is recorded in advance in the BCA (Burst Cutting Area) area.

  The optical disc apparatus of the present invention reproduces the control track area or the BCA area, and is processed according to a predetermined procedure, whereby interlayer distance information of the multilayer optical disc is converted into a predetermined circuit constituting the optical disc apparatus, for example, an interlayer It is set as a set value of the focus jump pulse generating means.

  The optical disc apparatus of the present invention reproduces the control track area or the BCA area, and is processed according to a predetermined procedure, so that the interlayer distance information of the multilayer optical disc is a predetermined apparatus constituting the optical disc apparatus, for example, a spherical surface. It is set as a set value of the operating point of the aberration correction means.

  According to the optical disc and the optical disc apparatus of the present invention, as is clear from the description of the means for solving the above-mentioned problem, the predetermined information constituting the optical disc device is directly reflected in the interlayer information possessed by the multilayer optical disc. It is adopted as a setting value of a circuit or device.

  Therefore, if the predetermined circuit is the interlayer focus jump pulse generating means, it is possible to know in advance the distance of movement of the objective lens during the interlayer focus jump operation. The set value to be set can be a set value suitable for the moving distance of the desired objective lens, and any recording / reproduction surface can be obtained without the need for an interlayer distance detecting means as described above. It is possible to easily realize the inter-layer focus jump operation.

  Further, if the predetermined apparatus is a spherical aberration correction means, the total interlayer distance between the desired recording / reproducing surface and the reference recording / reproducing surface, that is, the spherical aberration required for the reference recording / reproducing surface This means that it is possible to always know the spherical aberration correction amount necessary for the desired recording / reproducing surface based on the correction amount, and the operating point of the spherical aberration correcting means is immediately adapted to the target recording / reproducing surface. The set value can be set, and the spherical aberration correction operation of the optical disc apparatus can be easily and quickly performed.

  Furthermore, it becomes possible to relieve | moderate the restriction | limiting concerning the standard value about each interlayer distance significantly. That is, for example, by determining only the upper limit value of the interlayer distance, it is possible to ensure a high range of correlation distance values, and the interlayer distance value given for each manufacturer This means that the degree of freedom in making decisions increases, and the ratio of the effort required to converge the variations caused by the manufacturing process and the effort to converge the design value of the interlayer distance within a certain range increases. This effect can be expected.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a multilayer optical disc according to Embodiment 1 of the present invention. In FIG. 1, 50 shows the multilayer optical disc as viewed from above, and 51 shows a cross section of the multilayer optical disc. An area indicated by a thick solid circle 52 indicates a control track area of the multilayer optical disk, and an area indicated by a bold dashed circle 53 indicates a BCA (Burst Cutting Area) area of the multilayer optical disk.

  Note that both the control track area and the BCA (Burst Cutting Area) area are areas for recording the unique information of the multilayer optical disc in advance, and the control track is generally formed at the time of mastering, which is an optical disc manufacturing process. It cannot be modified.

  However, it is also possible to newly redefine a part of the recordable / reproducible area of the multilayer optical disc as a control track.

  BCA (Burst Cutting Area) is already defined by BD or the like, and is an area in which different information can be recorded in advance for each multilayer optical disc.

  On the other hand, 54, 55, 56,... In the cross section 51 indicate the recording / reproducing surfaces of the multilayer optical disc, and 57, 58,.

  Therefore, information on the distance between the respective layers 57, 58... Of the multilayer optical disc is recorded in the control track 52 or the BCA (Burst Cutting Area) area 53.

  FIG. 2 is a block diagram of the optical disk apparatus according to the present embodiment, and 1 is a multilayer optical disk according to the present invention, and the contents thereof have been clarified in the description of FIG. Reference numeral 2 in the multilayer optical disc 1 indicates a control track in which interlayer distance information is recorded in advance.

  The control track 2 may be recorded on any one recording / reproduction surface of the multilayer optical disc 1 or may be recorded on a plurality of recording / reproduction surfaces.

  A light beam 3 is controlled by the optical head 4. If FIG. 2 shows the situation at the time of reproduction of the control track 2 of the multilayer optical disc 1 described above, the information of the control track 2 is optically included in the light beam 3.

  The 5-focus servo circuit is supplied with a focus error signal 7 from the optical head 4 and is subjected to predetermined processing to drive and control a focus actuator mounted in the optical head 4 as a focus actuator drive signal 8. As a result, the focus servo is completed.

  Reference numeral 6 denotes a tracking servo circuit, but since the present embodiment relates only to focus control, description of tracking control is omitted.

  In FIG. 2, reference numeral 9 denotes an interlayer focus jump pulse generation circuit. Since the interlayer focus jump operation is generally performed in association with the focus servo, the interlayer focus jump pulse generation circuit 9 is a focus servo as shown in FIG. It is shown as being included in the circuit 5.

  On the other hand, a reproduction signal 10 generated by the optical head 4 is supplied to the reproduction processing circuit 11. The reproduction processing circuit 11 includes a function of extracting interlayer distance information 12 from the reproduction signal 10.

  Further, the interlayer distance information 12 extracted by the reproduction processing circuit 11 is supplied to the interlayer movement distance calculation means 13, and the interlayer movement distance calculation means 13 calculates a desired interlayer movement distance at the time of interlayer focus jump, and the interlayer movement distance information. 14 is supplied to and set in an interlayer focus jump pulse generation circuit 9 provided in the focus servo circuit 5.

  In FIG. 2, the reproduction processing circuit 11 and the interlayer movement distance calculation means 13 are shown as components having separate functions. However, as described above, the reproduction processing circuit 11 and the interlayer movement distance calculation means are used in this embodiment. It can also be considered that the two elements 13 constitute the reproduction processing means.

  Next, the interlayer movement distance calculation means 13 will be described with reference to FIG. As shown in FIG. 3, the interlayer movement distance calculation means 13 is mainly composed of a memory 20 and a CPU 23. The address 21 of the memory 20 corresponds to the interlayer number of the multilayer optical disc 1 of the present invention, and is stored in the data section 22 of the memory 20. If the respective interlayer distance information 12 of the multilayer optical disc 1 of the present invention is stored as interlayer distance data, n-1, n-2,... 22 a, b, c... Represent the distance between the layers.

  Accordingly, the situation of the memory 20 shown in FIG. 3 can be considered that the extraction of the interlayer distance information has already been completed and the supply of the interlayer distance information 12 to the interlayer movement distance calculation means 13 has been completed.

  Further, the CPU 23 appropriately reads necessary interlayer distance data from the memory 20, executes necessary arithmetic processing, and supplies and sets the interlayer movement distance information 14 to the interlayer focus jump pulse generation circuit 9 shown in FIG.

  Next, the interlayer focus jump pulse generation circuit 9 shown in FIG. 2 will be described with reference to FIG.

  In FIG. 4, 32 and 33 are an acceleration pulse level setting device and a deceleration pulse level setting device, respectively, whose output levels change according to the value of the interlayer movement distance information 14, and the respective output levels are This is input to the acceleration pulse generator 34 and the deceleration pulse generator 35.

  When the jump command 31 becomes active, the acceleration pulse generator 34 and the deceleration pulse generator 35 are accelerated pulses 36 corresponding to a predetermined pulse width and the output levels of the acceleration pulse generator 34 and the deceleration pulse generator 35 described above. , Deceleration pulses 37 are output and added by an adder 38 to complete generation of an interlayer jump pulse 39. At the time of interlayer jump, focus control generated in the focus servo circuit shown in FIG. By adding the signal and driving and controlling the focus actuator as the focus actuator drive signal 8, the interlayer focus jump is completed.

  The waveform of the generated interlayer jump pulse 39 is as shown in FIG. 5, but the acceleration pulse amplitude 40 and the deceleration pulse amplitude 41 are in accordance with the output levels of the acceleration pulse level setter 32 and the deceleration pulse level setter 33. It means that it changes according to the value of the interlayer movement distance information 14.

  The acceleration pulse level setting unit 32 and the deceleration pulse level setting unit 33 need to be configured so that their output levels change in accordance with the value of the interlayer movement distance information 14, but this includes a DA converter, an operational amplifier, etc. It can be easily realized by the combination.

  Further, if necessary, the acceleration pulse level setting unit 32 and the deceleration pulse level setting unit 33 can be configured to obtain different output levels with respect to the value of one interlayer movement distance information 14.

  Also, the configuration of the interlayer focus jump pulse generation circuit 9 shown in FIG. 4 includes an acceleration pulse level setter 32 and a deceleration pulse level setter 33 whose output levels change according to the value of the interlayer movement distance information 14. Except for the elements, it is the same as the track jump pulse generation circuit in the tracking control of a general optical disc apparatus, and does not involve any particular difficulty in its realization.

  According to the above-described configuration of the optical disc apparatus according to the first embodiment of the present invention, the operation (interlayer focus jump operation) is as follows.

  Now, it is assumed that the optical disc apparatus is reproducing an arbitrary recording / reproducing surface. At this time, as described above, the memory 20 shown in FIG. 3 (details of the interlayer movement distance calculation means 13 shown in FIG. 2) stores the interlayer distance information of the multilayer optical disc 1 of the present invention shown in FIG. It will be remembered.

  Therefore, when the optical disc apparatus causes an interlayer focus jump operation, the CPU 23 shown in FIG. 3 calculates from the memory 20 the interlayer movement distance between the desired recording / reproducing surface as the jump destination from the recording / reproducing surface currently being reproduced. In addition, the necessary interlayer distance data 22 is read, and an operation for calculating the interlayer movement distance is executed.

  For example, it is assumed that there are n, n + 1, n + 2 layers associated with the address 21 of the memory 20 shown in FIG. 3 between the current recording / reproducing surface and a desired recording / reproducing surface as a jump destination. Therefore, the CPU 23 reads the interlayer distances a, b, and c from the interlayer distance data 22, executes an addition operation to calculate a + b + c, and the value of a + b + c becomes the interlayer movement distance information 14, which is shown in FIG. Details of the interlayer focus jump pulse generation circuit 9 shown in FIG. 2) are set in the acceleration pulse level setter 32 and the deceleration pulse level setter 33 shown in FIG. After that, when the jump command 31 becomes active, the interlayer focus jump pulse 39 as shown in FIG. 5 is obtained as described above, and the levels of the acceleration pulse amplitude 40 and the deceleration pulse amplitude 41 are determined by the interlayer movement distance information 14 described above. When the interlayer jump pulse 39 is supplied to the focus actuator provided in the optical head 4 as the focus actuator drive signal 1 shown in FIG. 2, a desired interlayer focus jump operation is completed. It will be.

  Note that the operation of the CPU 23 may be modified as necessary, and the interlayer movement distance information 14 may be calculated as an absolute distance from the reference recording / reproducing surface.

  This correction is effective when configuring a spherical aberration correction device based on interlayer movement distance information 14 described later.

  Although the operation has been described here in the case where the number of layers involved in the interlayer focus jump is three, it is obvious that the present invention does not limit the number of layers.

  In addition, it is effective for realizing a jump operation across multiple recording / playback planes with a single interlayer focus jump operation instead of an interlayer focus jump with repeated jumps for each adjacent recording / playback plane. Can be expected to shorten.

  As described above, the interlayer focus jump constituting the optical disk apparatus in the present embodiment has been described. However, the fact that the interlayer distance can be known in advance is a spherical aberration correction apparatus (the optical disk apparatus includes a spherical aberration correction apparatus). Can be configured as shown below.

  FIG. 6 shows a spherical aberration correction apparatus that constitutes the optical disk apparatus according to the present embodiment.

  In FIG. 6, reference numeral 14 denotes interlayer movement distance information, which represents the absolute interlayer distance between the reference recording / reproduction surface and the desired recording / reproduction surface as described above, and 50 denotes interlayer movement distance information. 14 is an interlayer movement distance-to-voltage converter that generates a voltage corresponding to 14.

  On the other hand, the output voltage level of the interlayer movement distance versus voltage converter 50 is added to the reference voltage 51 (by the adder 52) and set as the operating voltage 53 in the spherical aberration correction element (for example, liquid crystal) 54. Accordingly, if the interlayer movement distance-to-voltage converter 50 and its output voltage level are appropriately related, the output light 56 is adapted to the above-described desired recording / reproducing surface with respect to the input light 55 of the spherical aberration correction element 54. Thus, a spherical aberration corrected light beam is obtained, and the spherical aberration correcting operation for the desired recording / reproducing surface is completed immediately. The output light 56 is irradiated onto the desired recording / reproducing surface, and the recording / reproducing operation is performed. Will be.

  The reference voltage 51 corresponds to the operating voltage of the spherical aberration correction element 54 for correcting the spherical aberration so as to match the reference recording / reproducing surface, and the interlayer movement distance information 14 is as described above. And the absolute distance from the reference recording / reproducing surface.

  Note that the spherical aberration correction element 54 shown in FIG. 6 is generally mounted inside the optical head 4 shown in FIG. 2, and in reality, a predetermined optical element is required around the periphery. However, the description and explanation are omitted in FIG.

  As described above, according to the present embodiment, the multilayer optical disc is a multilayer optical disc in which interlayer distance information is recorded in advance in the control track, and acceleration / deceleration of the interlayer jump pulse that governs the interlayer focus jump operation. Since the amplitude is determined based on the interlayer distance information, the amplitude of the acceleration / deceleration pulse is at a level suitable for the interlayer movement distance, and an interlayer focus jump operation between any recording and playback surfaces can be easily realized. It becomes possible to do.

  Further, in the spherical aberration correcting means device, since the correction amount of the spherical aberration suitable for the desired recording / reproducing surface is made based on the interlayer distance information of the optical disc, the spherical aberration detecting means is not required. The correction operation can be easily and quickly realized.

  The control track described above is generally formed at the time of mastering, which is the optical disk manufacturing process, as described in the description of the multilayer optical disk in the first embodiment of the present invention in FIG. Impossible. Therefore, when interlayer distance information is recorded in advance on such a control track, the interlayer distance information can be said to be a design value of the multilayer optical disc.

  However, if a part of the recordable / reproducible area of the multilayer optical disc is newly defined as a control track, the interlayer distance of the completed multilayer optical disc is measured, and the data is used as the interlayer distance information as the interlayer distance information. By adding information to the new control track or recording it on a BCA (Burst Cutting Area), it becomes possible to previously record different interlayer distance information for each multilayer optical disc. Even if the interlayer distance of the completed multilayer optical disc has variations, the effect of the present invention is not lost.

  When the interlayer distance information is read from the BCA, the reproduction signal 11 shown in FIG. 2 is generally different in format from the reproduction signal from the BCA. Accordingly, the reproduction processing circuit 11 in this case is adapted to the reproduction signal from the BCA.

  The multilayer optical disk and the optical disk apparatus according to the present invention guarantees the stability of the optical disk apparatus against the difference in interlayer distance between the multilayer optical disks or the variation in interlayer distance due to the problem in manufacturing the disk. Therefore, it is useful as a large-capacity optical disk drive, an optical disk recorder, etc. for recording / reproducing a multilayer optical disk, or an information recording medium thereof.

The figure of the multilayer optical disk of Embodiment 1 of this invention 1 is a block diagram of an optical disc device according to a first embodiment of the present invention. FIG. 3 is a block diagram of an interlayer movement distance calculation unit included in the optical disc apparatus according to Embodiment 1 of the present invention. 1 is a block diagram of an interlayer focus jump pulse generation circuit included in an optical disk device according to a first embodiment of the present invention. Interlayer focus jump pulse waveform diagram 1 is a block diagram of a spherical aberration correction device included in an optical disk device according to a first embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk 2 Control track 3 Light beam 4 Optical head 5 Focus servo circuit 6 Tracking servo circuit 7 Focus error signal 8 Focus actuator drive signal 9 Interlayer focus jump pulse generation circuit 10 Reproduction signal 11 Reproduction processing circuit 12 Interlayer distance information 13 Interlayer movement distance Calculation means 14 Interlayer movement distance information 54 Spherical aberration correction element

Claims (7)

It is a multilayer optical disc having a control track area for recording unique information in advance, and the unique information of the multilayer optical disc recorded on the control track includes interlayer distance information of the multilayer optical disc. A multi-layer optical disc. Interlayer distance information of the multilayer optical disc is recorded in advance in a BCA (Burst Cutting Area) area assigned to a predetermined area of the multilayer optical disc. The interlayer distance information is a measured value of the interlayer distance of the multilayer optical disc measured by a predetermined method, and the measured value of the interlayer distance of the multilayer optical disc is recorded in the BCA after the measurement value is measured. The multilayer optical disk according to claim 2. An optical disc apparatus for recording / reproducing a multilayer optical disc, comprising: a reproduction processing means for reproducing interlayer distance information from a control track area of the multilayer optical disc; An optical disc apparatus characterized in that the operation of a predetermined circuit or apparatus constituting the optical disc apparatus is determined. An optical disc apparatus for recording / reproducing a multilayer optical disc, comprising: a reproduction processing means for reproducing interlayer distance information from a BCA area of the multilayer optical disc; An optical disc apparatus characterized by determining a predetermined circuit constituting the apparatus or an operation of the apparatus. 6. The optical disc apparatus according to claim 4, wherein the predetermined circuit is a focus jump pulse generating unit, and the interlayer distance information is used to determine an output state of the focus jump pulse generating unit. 6. The optical disc apparatus according to claim 4, wherein the predetermined device is a spherical aberration correction unit, and the interlayer distance information is used to determine an operating point of the spherical aberration correction unit.

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