JP2008059627A - Optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To focus a laser beam in recording media different or various in substrate thickness while correcting an aberration. <P>SOLUTION: The optical disk device 300 is provided with: a focusing means 108 for focusing a laser beam LB in the recording layer of a position via the substrate of a first thickness; an aberration applying means 107 for applying an aberration to the laser beam; a first control means 314 for focusing the laser beam without applying any aberration; a second control means 314 for focusing, when a recording layer is formed in a position via the substrate of a second thickness smaller than the first thickness, the laser beam by applying the aberration of a first amount to be applied to the laser beam; and a third control means 314 for focusing the laser beam by applying the aberration of a second amount to be applied to the laser beam. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention belongs to the technical field of an optical disc apparatus that records data on or reproduces data from an information recording medium such as a DVD.

  For example, an information recording medium for optically recording and reproducing data using a laser beam or the like, such as a CD or a DVD, has been developed. Such information recording media have various substrate thicknesses. For example, a substrate thickness of 1.2 mm for a CD, a substrate thickness of 0.6 mm for a DVD or HD DVD, for example, Blu-ray. The disc has a substrate thickness of 0.1 mm. In order to record or reproduce data on such information recording media having different substrate thicknesses, it is necessary to focus laser light on the recording surface in accordance with each substrate thickness.

  On the other hand, when data is recorded on or reproduced from such information recording media having different substrate thicknesses with one objective lens, an aberration such as spherical aberration inherent to each information recording medium occurs. Furthermore, depending on the manufacturing conditions and the like, it is assumed that the substrate thickness varies (or errors), and aberrations also occur due to such substrate thickness variations. In order to correct this aberration, for example, techniques described in Patent Documents 1 to 4 have been developed.

JP 2004-206763 A JP 2004-14039 A JP 2002-157750 A JP 2003-99970 A

  However, the configuration described above corrects aberrations by feedback control or corrects aberrations after focusing laser light on the recording layer. Alternatively, the aberration is corrected after actually measuring the variation in the substrate thickness. For this reason, there is an adverse effect that the control for correcting the aberration may be complicated.

  The present invention has been made in view of, for example, the above-described conventional problems. For example, a laser while correcting aberrations such as spherical aberration for information recording media having different substrate thicknesses or variations in substrate thickness. It is an object of the present invention to provide an optical disc apparatus that makes it possible to focus light in.

  In order to solve the above problem, the optical disc apparatus according to claim 1 focuses laser light on a recording layer that is defined to be formed at a position through a substrate having a first thickness from the disc surface. A focusing unit; an aberration applying unit that applies aberration to the laser beam; and the aberration applying unit that controls the aberration so that no aberration is applied, and the focus unit is configured to focus the laser beam on the recording layer. A first control means for controlling, and a substrate having a second thickness that is thinner than the first thickness from the disk surface when the laser beam cannot be focused into the recording layer in a state where no aberration is applied. The aberration applying means so as to apply a first amount of aberration to be applied to the laser beam when the recording layer is formed at a position via A second control unit that controls the focusing unit so that the laser beam is focused on the recording layer in a state where the first amount of aberration is applied, and the first amount of aberration is When the laser beam cannot be focused into the recording layer in the applied state, the recording layer is located at a position from the disk surface via a substrate having a third thickness that is thicker than the first thickness. The aberration applying means is controlled so as to apply a second amount of aberration to be applied to the laser light when formed, and the laser is applied in a state where the second amount of aberration is applied. And third control means for controlling the focusing means so that light is focused into the recording layer.

  The operation and other advantages of the present invention will become apparent from the embodiments described below.

  Hereinafter, an optical disc apparatus according to an embodiment of the present invention as the best mode for carrying out the invention will be described in order.

  An embodiment of the optical disk device of the present invention includes a focusing means for focusing laser light onto a recording layer defined to be formed at a position through a substrate having a first thickness from the disk surface, and the laser light. An aberration applying unit for applying an aberration to the recording medium, a first control unit for controlling the aberration applying unit so as not to apply the aberration, and for controlling the focusing unit to focus the laser light on the recording layer; When the laser beam cannot be focused into the recording layer in a state where no aberration is applied, the recording is performed at a position through a substrate having a second thickness smaller than the first thickness from the disk surface. Controlling the aberration applying means so as to apply a first amount of aberration to be applied to the laser beam when a layer is formed; A second control unit that controls the focusing unit to focus the laser light on the recording layer in a state where the first amount of aberration is applied; and a state in which the first amount of aberration is applied. When the laser beam cannot be focused into the recording layer, the recording layer is formed at a position through the substrate having a third thickness larger than the first thickness from the disk surface. The aberration applying means is controlled so as to apply a second amount of aberration to be applied to the laser light, and the laser light is applied to the recording layer in a state where the second amount of aberration is applied. And third control means for controlling the focus means so as to focus in.

  According to the embodiment of the optical disc apparatus of the present invention, the laser beam can be focused into the recording layer provided in the optical disc by the operation of the focusing means. At this time, a desired amount of aberration is appropriately imparted to the laser light by the operation of the aberration imparting means. In this embodiment, for example, the standard defines that the recording layer is formed at a position through the substrate having the first substrate thickness from the disk surface. In other words, it is defined that the recording layer is formed on the other surface of the substrate having the first substrate thickness where one surface constitutes the disk surface. In other words, it is defined that the recording layer is formed at a position away from the disk surface by a distance corresponding to the first thickness. At this time, the optical disc is not necessarily provided with a single substrate having the first thickness, and if the recording layer is formed at a position separated from the disc surface by a distance corresponding to the first thickness, Its structure is not limited. When a plurality of types of optical discs having different substrate thicknesses are loaded on the optical disc apparatus according to the present embodiment, a plurality of first thicknesses may exist depending on the type of the optical disc.

  Particularly in the present embodiment, when the laser beam is focused on the recording layer, the laser beam is first recorded in a state in which the aberration is not imparted to the laser beam by the operation of the first control unit. Focus in the layer. As a result, when the laser beam is focused on the recording layer, the recording operation or the reproducing operation can be performed as it is. In this case, it can be determined that the substrate having the first thickness correctly has the first thickness.

  On the other hand, if the laser beam cannot be focused into the recording layer in a state where no aberration is applied to the laser beam, it can be determined that the thickness of the substrate has varied. That is, according to the standard, it can be determined that the substrate that should have the first thickness does not have the first thickness due to some influence. In this case, by the operation of the second control unit, the first amount of aberration is applied to the laser beam by the aberration applying unit, and the laser beam is applied to the recording layer with the first aberration applied. Let the focus in. The first amount is the amount of aberration to be imparted to the laser beam when the recording layer is formed at a position through the substrate having the second thickness thinner than the first thickness from the disk surface. In other words, the first amount corrects (that is, cancels out) aberrations caused by the recording layer being formed at a position through the substrate having the second thickness smaller than the first thickness from the disk surface. Is the amount of aberration to be given to the laser beam. As a result, when the laser beam is focused on the recording layer, the recording operation or the reproducing operation can be performed as it is. In this case, it can be determined that the substrate that should have the first thickness has a second thickness that is smaller than the first thickness.

  On the other hand, when the laser beam cannot be focused into the recording layer in a state where the first amount of aberration is applied to the laser beam, the laser beam is subsequently controlled by the operation of the third control unit. A second amount of aberration is imparted to the light by the aberration imparting means, and the laser light is focused on the recording layer in a state where the second aberration is imparted. The second amount is the amount of aberration to be imparted to the laser light when the recording layer is formed at a position from the disk surface via the third thickness substrate thicker than the first thickness. In other words, the second amount corrects (that is, cancels out) aberration caused by the recording layer being formed at a position through the substrate having the third thickness larger than the first thickness from the disk surface. Is the amount of aberration to be given to the laser beam. As a result, when the laser beam is focused on the recording layer, the recording operation or the reproducing operation can be performed as it is. In this case, it can be determined that the substrate that should have the first thickness has a third thickness that is greater than the first thickness.

  As described above, if the laser beam cannot be focused in without giving aberration, the substrate can be regarded as being thinner than the original thickness, and the laser beam can be given aberration and further focused in. Otherwise, the substrate is regarded as being thicker than the original thickness, and aberration is imparted to the laser light. For this reason, even if any of a plurality of types of optical discs having different substrate thicknesses is loaded or the substrate thickness varies, the laser beam is focused in while preferably correcting aberrations. be able to. In particular, according to this embodiment, it is not necessary to actually adjust the amount of aberration to be applied while actually measuring the thickness of the substrate or monitoring the reflected light of the laser beam. For this reason, it is possible to focus the laser beam on the recording layer relatively easily while correcting the aberration.

  One aspect of the embodiment of the optical disk apparatus of the present invention is characterized in that the second control means gives the aberration of the first amount based on the aberration amount information indicating the first amount. Control the applying means.

  According to this aspect, the second control unit imparts the first amount of aberration to the laser light based on the aberration amount information without performing a complicated calculation or the like (that is, relatively easily). Thus, the aberration applying means can be controlled.

  According to another aspect of the embodiment of the optical disc apparatus of the present invention, the third control unit applies the aberration of the second amount based on the aberration amount information indicating the second amount. Control the applying means.

  According to this aspect, the third control unit gives the second amount of aberration to the laser light based on the aberration amount information without performing a complicated calculation or the like (that is, relatively easily). Thus, the aberration applying means can be controlled.

  Another aspect of the embodiment of the optical disc apparatus of the present invention further includes storage means for storing aberration amount information indicating at least one of the first amount and the second amount.

  According to this aspect, by appropriately referring to the aberration amount information stored in the storage unit, the first amount of the laser light can be obtained without performing complicated calculation or the like (that is, relatively easily). The aberration imparting means can be controlled to impart an aberration or a second amount of aberration.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

  As described above, the embodiment according to the optical disc apparatus of the present invention includes the focus unit, the aberration applying unit, the first control unit, the second control unit, and the third control unit. Therefore, it is possible to focus in the laser light while correcting aberrations such as spherical aberration with respect to information recording media having different substrate thicknesses or variations in substrate thickness.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(Configuration of recording and playback device)
First, a basic configuration of an information recording / reproducing apparatus as an embodiment according to the optical disc apparatus of the present invention will be described with reference to FIG. FIG. 1 is a block diagram schematically showing the overall configuration of the information recording / reproducing apparatus 300 according to the present embodiment. The information recording / reproducing apparatus 300 has a function of recording data on each of a plurality of types of optical disks 10 having different substrate thicknesses and a function of reproducing data recorded on each of a plurality of types of optical disks 10 having different substrate thicknesses. With. In this embodiment, as a specific example of a plurality of types of optical disks 10, the description will be made assuming a CD with a substrate thickness of 1.2 mm and a DVD with a substrate thickness of 0.6 mm.

  As shown in FIG. 1, an information recording / reproducing apparatus 300 controls a disk drive 301 on which an optical disk 10 is actually loaded and data is recorded and reproduced, and data recording and reproduction on the disk drive 301. And a host computer 302 such as a personal computer.

  The disk drive 301 includes an optical disk 10, a spindle motor 311, an optical pickup 100, a signal recording / reproducing unit 313, a CPU (drive control unit) 314, a memory 315, a data input / output control unit 316, and a bus 317. . The host computer 302 includes a data input / output control unit 318, a CPU 319, a memory 320, a bus 321, an operation / display control unit 322, operation buttons 323, and a display panel 324.

  The optical pickup 100 includes, for example, a semiconductor laser device and a lens in order to record data on the optical disc 10. More specifically, the optical pickup 100 irradiates the optical disc 10 with the laser beam LB as the reading light at the first power during reproduction and at the recording power as the writing light with the second power while being modulated. The detailed configuration of the optical pickup 100 will be described later (see FIG. 2).

  The spindle motor 311 rotates and stops the optical disc 10 and operates when accessing the optical disc 10. More specifically, the spindle motor 311 is configured to rotate and stop the optical disk 10 at a predetermined speed while receiving spindle servo from a servo unit (not shown) or the like.

  The signal recording / reproducing means 313 records and reproduces data with respect to the optical disc 10 by controlling the spindle motor 311 and the optical pickup 100. More specifically, the signal recording / reproducing unit 313 includes, for example, a laser diode driver (LD driver), a head amplifier, and the like. The laser diode driver drives a laser chip provided in the optical pickup 100. The head amplifier amplifies the output signal of the optical pickup 100, that is, the reflected light of the laser beam LB, and outputs the amplified signal.

  The memory 315 is used in general data processing in the disk drive 301 such as a data buffer area and an area used as an intermediate buffer when data is converted into data usable by the signal recording / reproducing means 313. The memory 315 stores a program for operating as a recorder device, that is, a ROM area in which firmware is stored, a buffer for temporarily storing recording / playback data, and variables necessary for the operation of the firmware program and the like. It consists of a RAM area and the like.

  A CPU (drive control means) 314 is connected to the signal recording / reproducing means 313 and the memory 315 via the bus 317, and controls the entire disk drive 301 by giving instructions to various control means. Usually, software or firmware for operating the CPU 314 is stored in the memory 315.

  The data input / output control means 316 controls external data input / output to / from the disk drive 301 and stores and retrieves data from / in the data buffer on the memory 315. A drive control command issued from an external host computer 302 connected to the information recording apparatus 300 via an interface such as SCSI or ATAPI is transmitted to the CPU 314 via the data input / output control means 316. Similarly, data is exchanged with the host computer 302 via the data input / output control means 316.

  The operation / display control means 322 receives and displays an operation instruction with respect to the host computer 302, and transmits an instruction from the operation button 323 such as recording and reproduction to the CPU 319. The CPU 319 transmits a control command (command) to the information recording / reproducing apparatus 300 via the data input / output unit 318 based on the instruction information from the operation / display control unit 322 to control the entire disk drive 301. . Similarly, the CPU 319 can transmit a command requesting the disk drive 301 to transmit the operation state to the host. Thus, since the operation state of the disk drive 301 during recording can be grasped, the CPU 319 can output the operation state of the disk drive 301 to the display panel 324 such as a fluorescent tube or an LCD via the operation / display control means 322. .

  The memory 320 is an internal storage device used by the host computer 302. For example, a ROM area in which a firmware program such as BIOS (Basic Input / Output System) is stored, an operating system, variables necessary for the operation of an application program, etc. Is constituted by a RAM area or the like in which is stored. Further, it may be connected to an external storage device such as a hard disk (not shown) via the data input / output control means 318.

  One specific example in which the disk drive 301 and the host computer 302 described above are used in combination is a household device such as a recorder device that records video. This recorder device is a device for recording a video signal from a broadcast receiving tuner or an external connection terminal on a disc. The operation as a recorder device is performed by causing the CPU 319 to execute the program stored in the memory 320. In another specific example, the disk drive 301 is a disk drive (hereinafter referred to as a drive as appropriate), and the host computer 302 is a personal computer or a workstation. A host computer such as a personal computer and a drive are connected via data input / output control means 316 and 318 such as SCSI and ATAPI, and an application such as reading software installed in the host computer 302 controls the disk drive 301. .

  Next, a more detailed configuration of the pickup 100 included in the information recording / reproducing apparatus 300 according to the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram schematically showing a more detailed configuration of the pickup 100 in the information recording / reproducing apparatus 300 according to the present embodiment.

  As shown in FIG. 2, the optical pickup 100 includes a hologram laser 101, a collimator lens 104, a half mirror 105, a spherical aberration correction element 107, an objective lens 108, an actuator 109, a liquid crystal drive 111, a condensing light. A lens 112 and a photo detector 115 are provided.

  The hologram laser 101 includes a laser chip, a substrate, a hologram element, and the like that can emit laser light LB having a plurality of wavelengths (not shown). The laser chip emits a laser beam LB corresponding to the type of the optical disk 10 having a plurality of types. More specifically, the laser chip irradiates, for example, a laser beam LB having a wavelength of, for example, 780 nm (that is, an infrared laser beam) when recording or reproducing data on, for example, a CD, for example, When recording or reproducing is performed, for example, laser light LB having a wavelength of 660 nm (that is, red laser light) is irradiated.

  The collimator lens 104 makes the incident laser beam LB substantially parallel and enters the half mirror 105.

  The half mirror 105 transmits 100% of the laser beam LB incident from the hologram laser 101 side as it is, and reflects the laser beam LB incident from the optical disc 10 side (that is, the reflected light of the laser beam LB from the optical disc 10). . The reflected light reflected by the half mirror 105 is condensed on the photodetector 115 via the condenser lens 112.

  The spherical aberration correction element 107 constitutes one specific example of the “aberration providing means” of the present invention, and includes, for example, a liquid crystal panel. The spherical aberration correcting element 107 is a liquid crystal drive 111 that operates under the control of the CPU 314 constituting one specific example of “first control means”, “second control means”, and “third control means” in the present invention. In response, the refractive index in the liquid crystal panel is appropriately changed. More specifically, when the refractive index in the liquid crystal panel changes, the optical path or partial phase of the laser beam LB that passes through the spherical aberration correction element 107 changes, and as a result, spherical aberration is corrected.

  The objective lens 108 constitutes one specific example of the “focusing means” in the present invention, and condenses the incident laser beam LB and irradiates it on the recording surface of the optical disc 10.

  The actuator 109 constitutes one specific example of the “focus means” in the present invention, and has a drive mechanism for changing the arrangement position of the objective lens 108. More specifically, the actuator 109 moves the position of the objective lens 108 in the focus direction (the Z direction and the left and right directions in FIG. 2).

  The liquid crystal drive 111 drives a liquid crystal panel included in the spherical aberration correction element 107 under the control of the CPU 314. More specifically, the liquid crystal drive 111 applies a predetermined voltage to the spherical aberration correction element 107 under the control of the CPU 314, thereby changing the alignment state of the liquid crystal molecules in the liquid crystal panel included in the spherical aberration correction element 107. Change. As a result, the refractive index in the liquid crystal panel changes partially, and the spherical aberration is corrected.

  The condensing lens 112 condenses the reflected light reflected by the half mirror 105.

  The photodetector 115 receives the reflected light reflected by the half mirror 105 and detects the light intensity level and the like. The photo detector 115 outputs the detected light intensity level and the like to the CPU 314.

(Operational principle of information recording / reproducing device)
Next, the operation principle of the information recording / reproducing apparatus 300 according to the present embodiment will be described with reference to FIGS. FIG. 3 is a flowchart conceptually showing a process of the operation flow of the information recording / reproducing apparatus 300 according to the present embodiment. FIG. 4 shows the operation of the information recording / reproducing apparatus 300 according to the present embodiment. FIG. 5 is a graph conceptually showing the amount of spherical aberration applied in the spherical aberration correction element 107 in association with the substrate thickness.

  As shown in FIG. 3, under the control of the CPU 314, it is assumed that the loaded optical disk 10 is a DVD with a relatively thin substrate thickness, and the amount of spherical aberration applied by the spherical aberration correction element 107 is zero. (Step S101). That is, the spherical aberration amount given by the spherical aberration correction element 107 is set to be flat. Thereafter, the laser beam LB is focused on the loaded optical disc 10 (step S102). That is, the laser beam LB is focused into the recording layer included in the loaded optical disc.

  As a result of the operation in step S102, if the laser beam LB can be focused (step S102: Yes), the loaded optical disk 10 is a DVD and the substrate thickness is 0.6 mm. Can be determined. Therefore, thereafter, on the assumption that the loaded optical disk 10 is a DVD having a substrate thickness of 0.6 mm, the tracking servo is turned on as shown in FIG. 4 (step S114), and then data recording is performed. An operation or data reproduction operation is performed (step S115).

  On the other hand, when the focus pull-in of the laser beam LB cannot be performed as a result of the operation in step S102 (step S102: No), the loaded optical disk is not a DVD or a DVD whose substrate thickness is not 0.6 mm. Can be determined. In this case, subsequently, it is estimated that the loaded optical disk 10 is a CD having a relatively thick substrate, and the amount of spherical aberration applied by the spherical aberration correction element 107 is set to zero (step S103). . Thereafter, the laser beam LB is focused on the recording layer of the loaded optical disc 10 (step S104).

  As a result of the operation in step S104, when the focus pull-in of the laser beam LB can be performed (step S104: Yes), the loaded optical disk 10 is a CD and the substrate thickness is 1.2 mm. Can be determined. Therefore, after that, on the assumption that the loaded optical disk 10 is a CD having a substrate thickness of 1.2 mm, the tracking servo is turned on as shown in FIG. 4 (step S114), and then data recording is performed. An operation or data reproduction operation is performed (step S115).

  On the other hand, when the focus pull-in of the laser beam LB cannot be performed as a result of the operation in step S104 (step S104: No), the loaded optical disk is not a CD or a CD whose substrate thickness is not 1.2 mm. Can be determined. In this case, subsequently, the loaded optical disc 10 is estimated to be a DVD having a predetermined substrate thickness that is thinner than the substrate thickness of 0.6 mm defined by the DVD standard, and the spherical surface applied by the spherical aberration correction element 107. The amount of aberration is set to a predetermined negative value (step S105).

  Here, with reference to FIG. 5A, the amount of spherical aberration imparted by the spherical aberration correcting element 107 in step S105 of FIG. 3 will be described in more detail. FIG. 5A is a graph in which the horizontal axis represents the substrate thickness of a DVD, which is a specific example of the optical disc 10, and the vertical axis represents the amount of spherical aberration that occurs. This graph is expressed by the following equation: y = −14.5 × t + 8.7, where t is the substrate thickness and y is the amount of generated spherical aberration.

  As shown in FIG. 5A, when the substrate thickness is 0.6 mm, the amount of generated spherical aberration is substantially zero. Therefore, as shown in step S101 of FIG. 3, if the amount of spherical aberration applied by the spherical aberration correction element 107 is set to zero, the laser beam LB can be focused in.

  On the other hand, when the substrate thickness is thinner than 0.6 mm, positive spherical aberration occurs. For example, if the substrate thickness is 0.559 mm, the amount of generated spherical aberration is 0.60λ. For this reason, if the amount of spherical aberration applied by the spherical aberration correction element 107 is zero, spherical aberration occurs, and the laser light spot is blurred on the recording layer. For this reason, the laser beam LB cannot be focused. In the present embodiment, “the laser beam LB cannot be focused” refers to a state in which the laser beam LB cannot be focused into the recording layer at all. Even when the laser beam can be focused in, the signal intensity (specifically, the signal intensity of the reflected light of the laser beam) is relatively weak or is referred to when performing focus pull-in. This includes a state in which the recording operation or the reproducing operation cannot be suitably performed due to the relatively small peak-to-peak (p to p) of the signal. Therefore, in order to focus the laser beam LB, it is necessary to cancel this spherical aberration. In order to cancel this spherical aberration, it is necessary to impart −0.60λ spherical aberration to the laser beam LB by the spherical aberration correction element 107.

  In this embodiment, in particular, instead of actually measuring the substrate thickness of the optical disc 10, it is estimated or assumed that the substrate thickness is a predetermined thickness smaller than 0.6 mm, and the predetermined thickness is used. A spherical aberration for canceling the determined spherical aberration is applied to the laser beam LB by the spherical aberration correction element 107. In this case, it is preferable that the predetermined thickness that is estimated or regarded as less than 0.6 mm is predetermined. More specifically, for example, in step S105 of FIG. 3, it is estimated that the substrate thickness is 0.559 mm, which is thinner than 0.6 mm, and a spherical surface for canceling the spherical aberration 0.60λ determined by this 0.559 mm. An aberration of −0.60λ is applied to the laser beam LB by the spherical aberration correction element 107. In this case, the estimated or assumed substrate thickness of “0.559 mm” or the spherical aberration determined by the substrate thickness −0.60λ (or the spherical aberration −0.60λ for canceling the spherical aberration 0.60λ). Is preferably stored in advance in the memory 315 constituting one specific example of the “storage means” in the present invention.

  Similarly, in the application of spherical aberration described below, instead of actually measuring the substrate thickness of the optical disc 10, it is assumed that the substrate thickness is a predetermined thickness, or a predetermined spherical surface is assumed. Aberration is applied to the laser beam LB. Furthermore, it is preferable that the predetermined thickness estimated or assumed and the predetermined spherical aberration determined by the predetermined thickness are stored in the memory 315 in advance.

  In FIG. 3 again, the focus of the laser beam LB with respect to the loaded optical disk 10 is drawn with the spherical aberration −0.60λ applied to the laser beam LB by the operation of the spherical aberration correction element 107 (step S106). .

  If the focus pull-in of the laser beam LB can be performed as a result of the operation in step S106 (step S106: Yes), it is determined that the loaded optical disk 10 is a DVD whose substrate thickness is thinner than 0.6 mm. be able to. Therefore, thereafter, assuming that the loaded optical disk 10 is a DVD having a substrate thickness of less than 0.6 mm, as shown in FIG. 4, the spherical aberration correction element 107 gives spherical aberration −0.60λ. Then, after the tracking servo is turned on (step S114), a data recording operation or a data reproducing operation is performed (step S115).

  On the other hand, when the focus pull-in of the laser beam LB cannot be performed as a result of the operation in step S106 (step S106: No), the loaded optical disk is not a DVD or the substrate thickness is not thinner than 0.6 mm. It can be determined that it is a DVD. In this case, subsequently, the loaded optical disk 10 is estimated to be a CD having a predetermined substrate thickness that is thinner than the substrate thickness of 1.2 mm defined by the CD standard, and the spherical surface applied by the spherical aberration correction element 107. The amount of aberration is set to a predetermined negative value (step S107).

  Here, with reference to FIG. 5B, the amount of spherical aberration imparted by the spherical aberration correcting element 107 in step S107 of FIG. 3 will be described in more detail. FIG. 5B is a graph in which the horizontal axis represents the substrate thickness of a CD, which is a specific example of the optical disc 10, and the vertical axis represents the amount of spherical aberration that occurs. This graph is expressed by the following equation: y = −6.1 × t + 7.4, where t is the substrate thickness and y is the amount of generated spherical aberration.

  As shown in FIG. 5B, when the substrate thickness is 1.2 mm, the amount of generated spherical aberration is almost zero. Therefore, as shown in step S103 of FIG. 3, the laser light LB can be focused in by setting the amount of spherical aberration given by the spherical aberration correcting element 107 to zero.

  On the other hand, when the substrate thickness is thinner than 1.2 mm, positive spherical aberration occurs. For example, if the substrate thickness is 0.874 mm, the amount of generated spherical aberration is 2.0λ. Therefore, in order to focus the laser beam LB, it is necessary to cancel this spherical aberration. In order to cancel this spherical aberration, it is necessary to impart -2.0λ spherical aberration to the laser beam LB by the spherical aberration correction element 107.

  In FIG. 3 again, after that, the spherical aberration −2.0λ is given to the laser beam LB by the operation of the spherical aberration correction element 107, and the laser beam LB is focused on the loaded optical disc 10 (step S108). .

  If the focus pull-in of the laser beam LB can be performed as a result of the operation in step S108 (step S106: Yes), it is determined that the loaded optical disk 10 is a CD whose substrate thickness is thinner than 1.2 mm. be able to. Therefore, thereafter, assuming that the loaded optical disk 10 is a CD having a substrate thickness of less than 1.2 mm, as shown in FIG. 4, the spherical aberration correction element 107 gives a spherical aberration of −2.0λ. Then, after the tracking servo is turned on (step S114), a data recording operation or a data reproducing operation is performed (step S115).

  On the other hand, when the focus pull-in of the laser beam LB cannot be performed as a result of the operation in step S108 (step S108: No), the loaded optical disk is not a CD or the substrate thickness is not thinner than 1.2 mm. It can be determined that it is a DVD. In this case, subsequently, as shown in FIG. 4, it is estimated that the loaded optical disk 10 is a DVD having a predetermined substrate thickness that is thicker than the substrate thickness of 0.6 mm defined by the DVD standard. The amount of spherical aberration imparted by the element 107 is set to a predetermined plus value (step S109).

  Here, with reference to FIG. 5A, the amount of spherical aberration imparted by the spherical aberration correcting element 107 in step S109 of FIG. 4 will be described in more detail. As shown in FIG. 5A, when the substrate thickness is thicker than 0.6 mm, negative spherical aberration occurs. For example, if the substrate thickness is 0.641 mm, the amount of generated spherical aberration is −0.60λ. Therefore, in order to focus the laser beam LB, it is necessary to cancel this spherical aberration. In order to cancel this spherical aberration, it is necessary to apply a spherical aberration of 0.60λ to the laser beam LB by the spherical aberration correction element 107.

  In FIG. 4 again, after that, the spherical aberration 0.60λ is given to the laser beam LB by the operation of the spherical aberration correction element 107, and the laser beam LB is focused on the loaded optical disc 10 (step S110).

  When the focus pull-in of the laser beam LB can be performed as a result of the operation in step S110 (step S110: Yes), it is determined that the loaded optical disk 10 is a DVD whose substrate thickness is thicker than 0.6 mm. be able to. Therefore, thereafter, assuming that the loaded optical disk 10 is a DVD having a substrate thickness greater than 0.6 mm, the spherical aberration correction element 107 gives a spherical aberration of 0.60λ as shown in FIG. While the tracking servo is turned on while continuing (step S114), a data recording operation or a data reproducing operation is performed (step S115).

  On the other hand, when the focus pull-in of the laser beam LB cannot be performed as a result of the operation in step S110 (step S110: No), the loaded optical disk is not a DVD or the substrate thickness is not thicker than 0.6 mm. It can be determined that it is a DVD. In this case, subsequently, as shown in FIG. 4, the loaded optical disk 10 is estimated to be a CD having a predetermined substrate thickness that is thicker than the substrate thickness of 1.2 mm defined by the CD standard, and spherical aberration correction is performed. The amount of spherical aberration imparted by the element 107 is set to a predetermined plus value (step S111).

  Here, with reference to FIG. 5B, the amount of spherical aberration imparted by the spherical aberration correcting element 107 in step S111 of FIG. 4 will be described in more detail. As shown in FIG. 5B, when the substrate thickness is greater than 1.2 mm, negative spherical aberration occurs. For example, if the substrate thickness is 1.526 mm, the amount of generated spherical aberration is −2.0λ. Therefore, in order to focus the laser beam LB, it is necessary to cancel this spherical aberration. In order to cancel this spherical aberration, it is necessary to impart a spherical aberration of 2.0λ to the laser beam LB by the spherical aberration correction element 107.

  In FIG. 4 again, after that, the spherical aberration correction element 107 is operated to focus the laser beam LB on the loaded optical disc 10 with the spherical aberration of 2.0λ applied to the laser beam LB (step S112).

  If the focus pull-in of the laser beam LB can be performed as a result of the operation in step S112 (step S112: Yes), it is determined that the loaded optical disk 10 is a CD whose substrate thickness is thicker than 1.2 mm. be able to. Therefore, thereafter, assuming that the loaded optical disk 10 is a CD having a substrate thickness greater than 1.2 mm, as shown in FIG. 4, the spherical aberration correction element 107 gives a spherical aberration of 2.0λ. While the tracking servo is turned on while continuing (step S114), a data recording operation or a data reproducing operation is performed (step S115).

  On the other hand, when the focus pull-in of the laser beam LB cannot be performed as a result of the operation in step S112 (step S110: No), the loaded optical disk 10 is not a CD or the substrate thickness is thicker than 1.2 mm. It can be determined that there is no CD. In this case, the information recording / reproducing apparatus 300 determines that the recording operation or the reproducing operation cannot be performed on the loaded optical disc 10, and ejects the optical disc 10 (step S113).

  The operation of the information recording / reproducing apparatus 300 according to the present embodiment is summarized as follows. First, the optical disk 10 having the thinnest substrate thickness among a plurality of types of optical disks 10 that can be loaded on the information recording / reproducing apparatus 300 is loaded. presume. Thereafter, the laser beam LB is focused without applying spherical aberration by the spherical aberration correction element 107. If focus pull-in cannot be performed, it is presumed that the optical disk 10 having the second thinnest substrate among the plural types of optical disks 10 that can be loaded on the information recording / reproducing apparatus 300 is loaded, and the focus of the laser beam LB Pull in. Thereafter, until the focus can be pulled in, the same operation is repeated with the optical disc 10 having a thin substrate among the plurality of types of optical discs 10 that can be loaded into the information recording / reproducing apparatus 300 being preferentially operated. In the above-described example, after a DVD with a thin substrate thickness is preferentially targeted for operation, a CD with a thicker substrate than the DVD is targeted for operation.

  Thereafter, when the focus pull-in of the laser beam LB cannot be performed without applying spherical aberration by the spherical aberration correction element 107, the substrate thickness is larger than the original substrate thickness (for example, the substrate thickness determined by the standard). Estimated thin. Then, the spherical aberration for canceling the spherical aberration that occurs when the substrate thickness is thinner than the original substrate thickness is given to the laser beam LB by the operation of the spherical aberration correction element 107, and the focus pull-in of the laser beam LB is performed. Do. With respect to this operation as well, the optical disc 10 having the thin substrate thickness (that is, the original substrate thickness) among the plural types of optical discs 10 that can be loaded on the information recording / reproducing apparatus 300 is preferentially operated until the focus can be pulled. Repeated as a target.

  Thereafter, when the focus pull-in of the laser beam LB cannot be performed even when the spherical aberration is applied to cancel the spherical aberration that occurs when the substrate thickness is smaller than the original substrate thickness, the substrate thickness is the original substrate. Estimated to be thicker than the thickness. Then, the spherical aberration for canceling the spherical aberration that occurs when the substrate thickness is thicker than the original substrate thickness is given to the laser beam LB by the operation of the spherical aberration correction element 107, and the laser beam LB is focused. Do. This operation is also repeated with priority given to the optical disc 10 having a thin substrate thickness among the plural types of optical discs 10 that can be loaded into the information recording / reproducing apparatus 300 until the focus can be pulled.

  As described above, according to the information recording / reproducing apparatus 300 in the embodiment, even if any one of a plurality of types of optical disks having different substrate thicknesses is loaded, or the substrate thickness varies. Even so, it is possible to focus in the laser light while preferably correcting the aberration. In particular, according to this embodiment, it is not necessary to actually adjust the amount of aberration to be applied while actually measuring the thickness of the substrate or monitoring the reflected light of the laser beam. Therefore, the laser beam LB can be focused on the recording layer while correcting the aberration relatively easily.

  In the above-described embodiment, the description has been made by taking CD and DVD as examples of the optical disc 10 loaded in the information recording / reproducing apparatus 300. However, it goes without saying that other types of optical disks may be loaded onto the information recording / reproducing apparatus 300. For example, a Blu-ray Disc having a substrate thickness of 0.1 mm may be loaded on the information recording / reproducing apparatus 300. In this case, since the substrate thickness of the Blu-ray Disc is thinner than the substrate thickness of the CD or DVD, after the optical disc 10 is loaded, it is first estimated that the loaded optical disc 10 is a Blu-ray Disc. The light LB is focused into the recording layer. Subsequent operations when estimating that the substrate thickness is thinner than the original substrate thickness and operations when estimating that the substrate thickness is thicker than the original substrate thickness are given priority in the order of Blu-ray Disc, DVD, CD. Is subject to action.

  In addition to the optical disc 10 having a single recording layer, a two-layer type optical disc having two recording layers or a multilayer type optical disc having three or more recording layers is loaded on the information recording / reproducing apparatus 300. You may comprise. In this case, the recording layer positioned closer to the laser beam LB when viewed from the side irradiated with the laser beam LB (that is, viewed from the optical pickup 100) is preferentially selected as an operation target, and the laser is not applied with the above-described aberration. An operation for focusing the light LB, an operation for estimating that the substrate thickness is thinner than the original substrate thickness, and an operation for estimating that the substrate thickness is thicker than the original substrate thickness are performed. In the case of a two-layer or multilayer optical disk, the substrate thickness corresponds to the distance from the disk surface to the recording layer.

  In the above-described embodiment, the substrate thickness when the substrate thickness is estimated to be thinner than the original substrate thickness, the substrate thickness when the substrate thickness is estimated to be thicker than the original substrate thickness, and these substrate thicknesses. The spherical aberration (or spherical aberration for canceling the spherical aberration) determined by the above is stored in the memory 315 in advance. However, the graphs shown in FIGS. 5A and 5B (or mathematical expressions indicating the graphs) may be stored in the memory 315 in advance. However, even when storing the graph, the substrate thickness when estimating that the substrate thickness is thinner than the original substrate thickness, or the substrate thickness when estimating that the substrate thickness is thicker than the original substrate thickness, It is preferable that it is predetermined.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and an optical disc apparatus accompanying such a change. Is also included in the technical scope of the present invention.

It is a block diagram which shows roughly the whole structure of the information recording / reproducing apparatus based on a present Example. It is a block diagram which shows roughly the more detailed structure of especially a pickup among the information recording / reproducing apparatuses based on a present Example. 3 is a flowchart conceptually showing one process of an operation flow of the information recording / reproducing apparatus in the example. It is a flowchart which shows notionally the other process of the flow of operation | movement of the information recording / reproducing apparatus based on a present Example. It is a graph which shows notionally the quantity of spherical aberration provided in a spherical aberration correction element in correspondence with substrate thickness.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical disk 100 Optical pick-up 101 Hologram laser 104 Collimator lens 107 Spherical aberration correction element 108 Objective lens 109 Actuator part 111 Liquid crystal drive 115 Photo detector 300 Information recording / reproducing apparatus 313 Signal recording / reproducing means 314 CPU
315 memory

Claims (4)

Focusing means for focusing laser light on a recording layer that is defined to be formed at a position through a substrate having a first thickness from the disk surface;
An aberration applying means for applying an aberration to the laser beam;
First control means for controlling the focusing means so as to focus the laser light on the recording layer, while controlling the aberration giving means so as not to give aberration;
When the laser beam cannot be focused into the recording layer in a state where no aberration is applied, the recording layer is located at a position through the substrate having a second thickness smaller than the first thickness from the disk surface. And the aberration applying means is controlled so as to apply a first amount of aberration to be applied to the laser light, and the first amount of aberration is applied in the state where the first amount of aberration is applied. Second control means for controlling the focusing means so as to focus laser light on the recording layer;
When the laser beam cannot be focused into the recording layer in a state where the first amount of aberration is applied, a substrate having a third thickness that is thicker than the first thickness is formed from the disk surface. When the recording layer is formed at an intermediate position, the aberration applying means is controlled so as to apply a second amount of aberration to be applied to the laser beam, and the second amount of aberration is controlled. And a third control unit that controls the focusing unit so that the laser beam is focused into the recording layer in a state where the laser beam is applied.   The said 2nd control means controls the said aberration provision means so that the said 1st amount of aberration may be provided based on the aberration amount information which shows the said 1st amount. Optical disk device.   The said 3rd control means controls the said aberration provision means so that the said 2nd amount of aberration may be provided based on the aberration amount information which shows the said 2nd amount. Optical disk device.   2. The optical disc apparatus according to claim 1, further comprising storage means for storing aberration amount information indicating at least one of the first amount and the second amount.

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