JP4492551B2 - Optical spot movement control device and optical disc device - Google Patents

Description

  The present invention relates to an optical disk apparatus, and more particularly to an optical disk apparatus that performs CLV (constant linear velocity) control and realizes access that does not cause reproduction light degradation during access accompanied by interlayer movement.

  Conventionally, in Patent Document 1, a seek operation is performed so as to minimize the possibility of a focus jump error due to a disc surface wobbling factor so that an access operation can be completed more quickly. It is an object.

For this reason, a disk drive device for recording or reproducing data by irradiating the signal recording surface with a laser beam on a disk-shaped recording medium having a plurality of signal recording surfaces having a layer structure is configured as follows. Is. That is, this apparatus moves at least the laser light source, the objective lens serving as the output end of the laser light, the pickup means having the detection unit for detecting the reflected light from the recording medium, and the objective lens in the direction of contacting and separating from the recording medium The objective lens moving means for setting the focus state of the objective lens with respect to the signal recording surface of the recording medium, and the objective lens is moved from one signal recording surface to which the objective lens is currently focused to another signal recording surface. Focus jump control means for controlling the objective lens moving means so that a focus jump for focusing is performed, and a disc radial direction for displacing the relative positional relationship between the objective lens and the radial direction of the disc-shaped recording medium Transporting means. In addition, the seek operation for executing the next seek control as the seek operation performed when the current address position at which the objective lens is currently focused and the target address position as the access destination are not the same signal recording surface Control means are provided. In other words, when it is determined that the target address position is on the inner circumference from the current address position, the objective lens reaches the radial position of the disc-shaped recording medium corresponding to the target address position on the signal recording surface including the current address position. Is controlled so as to be positioned in the radial direction of the disk, and thereafter the focus jump control means so that a focus jump is performed from the transfer completion position in the radial direction of the disk to the signal recording surface including the target address position. When it is determined that the target address position is on the outer periphery of the current address position, the focus is applied from the current address position to the signal recording surface including the target address position. Focus Jar so that the jump is performed The control by the disk control means is executed, and then the control for the disk radial direction transfer means is executed so that the objective lens is positioned from the focus jump completion position to the radial position of the disk-shaped recording medium corresponding to the target address position. 2 seek control. According to this conventional configuration, when access is made between different signal recording surfaces corresponding to a disk on which a plurality of signal recording surfaces having a layer structure are formed, the inner circumference is changed between the current address position and the target address position. A focus jump is executed at the disk radial position corresponding to the address position closer to the side (the one with less surface shake).
JP 2000-251271 A

  However, the above-mentioned conventional technology is divided into zones for each predetermined radius, such as the CLV method in which the relative linear velocity of the light beam typified by DVD-R or DVD-RAM is used, and the average linear velocity in each zone is constant. When using the optical recording / reproducing apparatus that performs recording / reproduction using the ZCLV method of the above, when performing the search operation to move the light beam to the target track on the optical recording medium with the set reproduction power, the appropriate amount of energy is used. However, a strong light beam may be irradiated. For example, when the light beam moves in the direction from the outer periphery to the inner periphery of the optical recording medium, the rotation control means is controlled so as to increase the rotation speed of the optical recording medium in order to maintain a predetermined linear velocity. . However, if the rising speed at which the rotational speed increases to the target value is delayed, the relative linear velocity between the light beam and the optical recording medium decreases. For this reason, since the irradiation energy per unit time irradiated per unit area on the optical recording medium is substantially increased, the recording signal may be deteriorated.

  In order to prevent the deterioration of these recording signals, increase the driving force of the motor that rotates the optical disc, and then start the rotational drive of the motor before or simultaneously with the radial movement, and wait for the rotation speed to follow. Or move in the radial direction while following.

  In the case of a configuration in which the focus jump is always executed at the inner periphery as in the prior art, for example, when moving from the inner periphery to the outer periphery, the motor is activated on the inner periphery and the focus jump from the first layer to the second layer is performed. At this point, the rotational speed of the motor has fallen below a predetermined linear velocity, which may cause degradation of the reproduction light. In particular, in a part of a two-layer recordable DVD disk, and particularly in a two-layer high-density optical disk using a blue laser, it is necessary to switch the correction of spherical aberration between layers when moving between layers by a focus jump. Furthermore, since the access time is increased, there is a problem that the reproduction light deterioration problem becomes more prominent. Alternatively, in the movement from the outer circumference to the inner circumference, if the motor is started on the outer circumference and moved in the radial direction, the motor follows more slowly than the movement in the radial direction, so the linear velocity is lower than a predetermined value on the inner circumference. May cause deterioration of playback light.

  Accordingly, the present invention has been made to solve such a problem, and prevents deterioration of a recording signal due to reproduction light in access on a multi-layer disc, and high-speed and high-performance light that is highly safe in information storage. An object of the present invention is to provide a spot movement control device and an optical disk device.

  In order to achieve the above object, a light beam spot movement control device of the present invention has at least two information surfaces stacked, and is focused on the information surface of an optical disc that performs recording or reproduction at a substantially constant linear velocity. A light beam spot movement control device that performs control to move a light beam spot, wherein the light beam spot is moved from any one of the information surfaces to another information surface, and the inner circumference direction of the optical disc When the light beam spot is moved, the light beam spot is moved in the inner circumferential direction after the light beam spot is moved to the other information surface, and the other information surface is moved from the other information surface to the other information surface. When moving the light beam spot to the information surface and moving the light beam spot in the outer peripheral direction of the optical disc, After moving the light beam spot, and performs control for moving the optical beam spot to the other information surface.

In order to achieve the above object, an optical disc apparatus according to the present invention has at least two information surfaces stacked and an information track formed on the information surface, and performs recording or reproduction at a substantially constant linear velocity. An optical disk apparatus for accessing the optical disk, wherein a rotation control means for controlling the optical disk to rotate at a constant linear speed, a focusing means for focusing a light beam on the information surface, and the information surface substantially A vertical movement means for moving the focusing means in a direction perpendicular to the focusing plane; a focus detection means for generating a signal corresponding to the focusing state of the light beam on the information surface; and the vertical movement in response to a signal from the focus detection means And a focus control means for controlling the light beam on the information surface to be substantially constant and a light beam focused on any of the information surfaces. Any one of information plane movement control means for controlling the movement of the optical spot to the other information plane, inner / outer peripheral movement means for moving the light beam spot in the inner or outer circumferential direction of the optical disc, and the information track Light beam spot movement control means for controlling the movement of the light beam spot to the position of the light beam spot movement control means, the light beam spot movement control means from one of the information surfaces to the other information surface. When moving the spot and moving the light beam spot in the inner circumferential direction, the rotation speed of the motor is accelerated by the rotation control means, and the other information is moved by the information plane movement control means. after moving the light beam spot on the surface, by the inner periphery moving means moves the optical beam spot in said circumferential direction, before When the light beam spot is moved from any information surface to the other information surface and the light beam spot is moved in the outer circumferential direction, the rotational speed of the motor is reduced by the rotation control means. Then, after the light beam spot is moved in the outer peripheral direction by the inner / outer periphery moving unit, the information surface movement control unit performs control to move the light beam spot to the other information surface. And

  The optical disk apparatus according to the present invention optimizes the sequence of spindle motor drive, radial movement by traverse, and interlayer jump in accessing information recorded on a multilayer disk to prevent deterioration of the recording signal due to reproduction light and high-speed access. It is possible to achieve both.

Embodiments of an optical spot movement control device and an optical disc apparatus according to the present invention will be described below in detail with reference to the drawings. The configurations of the light spot movement control device and the optical disk device according to the embodiment of the present invention will be described.
(Embodiment 1)
FIG. 1 is a diagram showing a light beam spot movement control unit according to an embodiment of the present invention. The light beam spot movement control unit 104 according to the first embodiment performs control to move the light beam spot focused on the information surface of the information carrier 102 having at least two information surfaces stacked. The light beam spot movement control unit 104 is a case where the light beam spot is moved from one information surface to another information surface, and when the light beam spot is moved in the outer circumferential direction of the information carrier 102, the rotation control unit 104 A deceleration command is sent to 800, the light beam spot is moved in the outer circumferential direction, and the light beam spot is moved to another information surface.

  When moving a light beam spot from any information surface to another information surface and moving the light beam spot in the inner circumferential direction of the optical disc, an acceleration command is sent to the rotation control unit 800 to send other information information. Control is performed to move the light beam spot to the surface and move the light beam spot in the inner circumferential direction.

  The light beam spot movement control unit 104 controls the optical disc apparatus 100 that accesses the information carrier 102. The light beam spot movement control unit 104 performs control for searching for a desired information track on a target information plane, that is, a destination information plane. The light beam spot movement control unit 104 determines whether to perform a focus jump. The light beam spot movement control unit 104 determines whether the movement is in the inner circumferential direction or the outer circumferential direction, and the movement control of the light beam spot is performed according to a procedure according to whether the movement is in the inner circumferential direction or the outer circumferential direction. I do. As a result, when moving from the outer circumference to the inner circumference in the presence of a response delay of the spindle motor, the focus jump is first executed, and the rotation control means is accelerated while the light beam is at the outer circumference position. Control in the direction of up. Conversely, when moving from the inner periphery to the outer periphery, first move in the radial direction and decelerate the rotation control means while the light beam is at the inner peripheral position, but the movement in the radial direction is usually within a few hundred ms even with a full stroke. Therefore, the linear velocity is effectively controlled to increase.

  By controlling as described above, it is possible to efficiently suppress the deterioration of information due to reproduction light, and by simultaneously rotating the spindle during the focus jump time, the overhead is reduced and the total access between layers is achieved. Time can be shortened.

  The information carrier 102 is a recording medium that can be accessed by a light beam. The information carrier 102 is, for example, an optical disc. The information carrier 102 may be a DVD-ROM or DVD-RAM, DVD-RW, DVD-R, + RW, + R, a disk in which two or three or more layers are formed, or a high density using blue light or the like. The optical disc may be a disc in which two or three or more optical discs are formed.

  FIG. 2 is a diagram showing a schematic functional configuration of the optical disc apparatus 100 shown in FIG. The optical disc apparatus 100 includes a focusing unit 110, an inner / outer peripheral movement unit 112, a vertical movement unit 114, a focus detection unit 116, a focus control unit 118, an information surface movement control unit 120, and a light beam spot movement control unit 104. And comprising. The focusing unit 110 focuses the light beam on the information surface of the information carrier 102. The focusing unit 110 is, for example, an optical lens (objective lens). The converging unit 110 may be, for example, an optical lens having an NA of 0.6 or more, or an optical lens having an NA of 0.8 or more. The vertical moving unit 114 moves the converging unit 110 in a direction substantially perpendicular to the information surface. The vertical moving unit 114 is, for example, an actuator.

  The focus detection unit 116 generates a signal corresponding to the focused state of the light beam on the information surface. The focus detection unit 116 generates an error signal related to the vertical direction between the light beam spot and the information carrier 102, for example. The focus control unit 118 drives the vertical movement unit 114 in accordance with the signal from the focus detection unit 116, and controls the light beam focusing state on the information surface to be substantially constant. The focus control unit 118 turns off the focus control before the focus jump is performed, and turns on the focus control after the focus jump, for example. The information surface movement control unit 120 performs control to move a light beam spot focused on any information surface to another information surface. For example, the information surface movement control unit 120 drives the vertical movement unit 114 and controls the focus jump.

  The inner / outer peripheral moving unit 112 moves the light beam spot in the inner peripheral direction or the outer peripheral direction of the information carrier 102. For example, the inner / outer periphery moving unit 112 transfers the light beam spot in a direction crossing the information track formed on the information surface of the information carrier 102. For example, the inner / outer periphery moving unit 112 moves the light beam spot by moving the focusing unit 110 in the inner or outer circumferential direction of the information carrier 102.

  FIG. 3 is a diagram illustrating an example of a hardware configuration of the optical disc apparatus 100 illustrated in FIG. The optical disc apparatus 100 includes a disc motor 140, an optical head device 122, a preamplifier 126, a focus actuator drive circuit 136, a transfer table 124, a transfer table drive circuit 134, a focus error generator 128, and a focus control unit 130. And a microcomputer 132. The disk motor 140 rotates the information carrier 102 at a predetermined linear velocity (number of rotations) by the rotation control means 800.

  The microcomputer 132 controls the rotation controller 800, the focus actuator drive circuit 136, and the transfer table drive circuit 134. Further, the microcomputer 132 performs filter operations such as phase compensation and gain compensation on the FE signal from the focus error generator 128 and outputs a control signal. The focus actuator drive circuit 136 drives a focus actuator 143 (to be described later) of the optical head device 122 in accordance with a control signal from the focus control unit 130 in the microcomputer 132.

  In place of the microcomputer 132, a DSP (digital signal processor) may be used. The transfer table driving circuit 134 outputs a drive signal to drive the transfer table 124. The transfer table 124 moves the optical head device 122 in the radial direction of the information carrier 102. The optical head device 122 outputs a light beam and forms a light beam spot on the information surface of the information carrier 102. The optical head device 122 receives the reflected light from the information carrier 102 and outputs a signal corresponding to the reflected light. The preamplifier 126 converts a current signal from a light receiving unit 144 (to be described later) of the optical head device 122 into a voltage signal.

  The focus error generator 128 receives a signal from the preamplifier 126 and outputs a focus shift signal (FE signal). The FE signal is a signal for controlling the light beam to be in a predetermined focused state on the information surface of the information carrier 102. The detection method of the FE signal is not particularly limited, and an astigmatism method may be used, a knife edge method may be used, or an SSD (spot sized detection) method may be used. It may be a thing.

  FIG. 4 is a diagram showing a schematic configuration of the optical head device 122 shown in FIG. The optical head device 122 includes a light source 146, an optical lens (objective lens) 142, a light receiving unit 144, and a focus actuator 143. The light source 146 outputs a light beam. The light source 146 is, for example, a semiconductor laser. The light source 146 may output a light beam having a wavelength of 680 nm or less, or may output a light beam having a wavelength of 410 nm or less.

  The optical lens 142 focuses the light beam output from the light source 146 and forms a light beam spot on the information surface of the information carrier 102. Further, the optical lens 142 allows the reflected light from the information carrier 102 to pass through. The light receiving unit 144 receives the reflected light from the information carrier 102 that has passed through the optical lens 142 and converts the optical signal into an electrical signal (current signal). For example, the light receiving unit 144 is divided into four parts. The focus actuator 143 moves the optical lens 142 in a direction substantially perpendicular to the information surface of the information carrier 102.

  The optical lens 142 corresponds to the converging unit 110 in FIG. The light receiving unit 144, the preamplifier 126, and the focus error generator 128 correspond to the focus detection unit 116 in FIG. Further, the focus actuator drive circuit 136 and the focus actuator 143 correspond to the vertical movement unit 114 in FIG. The microcomputer 132 and the focus control unit 130 embody the light beam spot movement control unit 104, the information surface movement control unit 120, and the focus control unit 118 of FIG.

  FIG. 5 shows an example of the information carrier 102 shown in FIG. The information carrier 102 includes a substrate 150, information surfaces L0, L1, and L2, and a protective film 152. The information carrier 102 is configured such that each information surface L0-L2 can be accessed from one surface. The information carrier 102 has a thickness of 1.2 mm. The protective film 152 transmits the light beam from the optical lens 142. The substrate 150 has a thickness of 1.1 mm. The three layers of information surfaces L0 to L2 are arranged at intervals of 25 μm or less. For example, the information surface L0 is disposed at a position of 100 μm from the surface of the protective film 152. The information surface L1 is disposed at a position of 75 μm from the surface of the protective film 152. The information surface L2 is disposed at a position of 50 μm from the surface of the protective film 152.

  FIG. 6 is a diagram showing a configuration of an information track of the information carrier 102 according to the first embodiment. On the information surfaces L0 to L2 of the information carrier 102, convex information tracks 160 are formed. As a result, the information surfaces L0 to L2 are uneven. The optical head device 122 irradiates the information surfaces L0 to L2 with a light beam from the side on which the information track 160 is formed.

  In the above configuration, the operation of the embodiment will be described with reference to FIGS. FIG. 7 is an explanatory diagram for explaining the movement of the light beam spot in the inner circumferential direction and the outer circumferential direction according to the embodiment. As shown in FIG. 7, the inner and outer periphery moving unit 112 moves the light beam spot in the inner or outer peripheral direction of the information carrier 102. FIG. 8 is a flowchart showing a flow of light beam spot movement control according to the first embodiment. This light beam spot movement control is performed when the light beam spot is moved from one information surface to another information surface and is moved in the inner peripheral direction or the outer direction of the optical disc.

  FIG. 10 is a characteristic diagram showing response characteristics of a general motor. FIG. 10 shows the movement time of the optical head by the transfer table 124 and the response time of the number of rotations of the disk by the disk motor 140 in the search of the full stroke of the 12 cm diameter disk that can be realized by the normal disk motor 140 and the transfer table 124. FIG. 10A shows a case where the optical disk moves from the inner periphery to the outer periphery, and FIG. 10B shows a case where the optical disk moves from the outer periphery to the inner periphery.

  In this light beam spot movement control, in S100, the light beam spot movement control unit 104 first determines whether the movement is in the inner circumferential direction or the outer circumferential direction. For example, when performing the focus jump, the light beam spot movement control unit 104 determines whether a desired information track on the target information surface is in the inner circumferential direction or the outer circumferential direction.

  If it is determined to move in the outer circumferential direction, in S202, the light beam spot movement control unit 104 gives a deceleration command to the rotation control unit 800, and in S106, the light beam spot movement control unit 104 causes the inner / outer circumferential movement unit 112 to Control is performed so that the beam spot moves in the outer circumferential direction to the target position.

  The straight line at the black square point in FIG. 10A shows the time required when the optical head moves from the position of the innermost circumference r = 25 mm to the outermost circumference r = 58 mm, and reaches the position of 58 mm after 180 ms. Yes. Further, the curve indicated by the ▲ point in FIG. 10A shows the response of the rotational speed of the disk motor. At this time, the disk motor 140 quickly decelerates from the innermost rotation speed of 1800 rpm, and when the optical head reaches 58 mm of the outermost periphery, the disk motor follows 1100 rpm and about 40% or more. Then, since the linear velocity is sufficiently high, there is no deterioration of the reproduction light. Further, while the optical head is positioned on the outermost periphery, the disk motor continues to decelerate to a predetermined rotational speed of 776 rpm. At the same time, in S102, the information surface movement control unit 120 causes the light beam spot to be the target information. Control to move to the surface. This movement time takes about 10 ms for the movement of the light beam and about 100 ms for the confirmation of the address in the desired layer. When moving to the desired information surface, the response is reduced to 800 rpm and 80% or more.

  On the other hand, when it is determined to move in the inner circumferential direction, the light beam spot movement control unit 104 gives an acceleration command to the rotation control unit 800 in S200, and in S102, the information surface movement control unit 120 causes the light beam spot to be the target. Control to move to the information surface. This movement time takes about 10 ms for the movement of the light beam and about 100 ms for address confirmation in the desired layer.

  The straight and dotted lines of the black squares in FIG. 10B indicate the time required when the optical head moves from the position of the outermost circumference r = 58 mm to the innermost circumference r = 25 mm. The dotted curve shows the response of the rotational speed of the disk motor at this time.

After the acceleration command, the disk motor 140 accelerates rapidly from the outermost rotation speed of 776 rpm, and follows up to 1000 pm when the target information surface is moved by the information surface movement control unit 120, but it follows 1000 pm. Since the speed changes in the fast direction, there is no possibility of deterioration of the reproduction light. Thereafter, in S104, the inner and outer periphery moving unit 112 controls the light beam spot to move to the target position in the inner periphery direction. At this time, the disk motor keeps responding toward the innermost target rotation speed, and when the transfer table reaches 25 mm, it responds to 1500 rpm and 80% or more, so the possibility of degradation of the reproduction light is extremely high. Low. Furthermore, since the moving time of the optical head from 58 mm to 25 mm is known in advance and is almost stable,
After moving between the layers as indicated by the solid line of the black square in the figure, after waiting for the motor response time at the outer peripheral position, the inner / outer peripheral moving unit 112 starts moving the light beam spot to the target position in the inner peripheral direction. You may control to do.

  Here, the focus jump process will be described in detail. FIG. 9 is a flowchart showing the flow of the focus jump process (S102) shown in FIG. In this focus jump process, first, the microcomputer 132 turns off tracking control (S112). The focus control unit 130 holds a drive signal for focus control (S114). Next, the focus control unit 130 generates an acceleration pulse signal and a deceleration pulse signal and applies them to the focus actuator 143 via the focus actuator drive circuit 136 (S116). As a result, the light beam spot moves to the target information surface.

  When the FE signal reaches the target information surface pull-in level, the focus control unit 130 turns off the hold of the drive signal for focus control and puts focus control into an operating state (S118). Next, the focus control unit 130 confirms that the focus is normally drawn based on a signal such as a track deviation signal (TE signal) or an RF signal (S120). Next, the microcomputer 132 activates the tracking control and searches for a predetermined track / sector address (S122).

(Embodiment 2)
When the spherical aberration is switched in the light beam spot movement control shown in FIG. 8, the effect of the present invention is further increased.

  FIG. 11 is a diagram showing a light beam spot movement control unit according to the embodiment of the present invention. The information surface movement control unit 402 according to the second embodiment moves a light beam spot focused on one of the information surfaces of the optical disk 102 having at least two information surfaces stacked to another information surface and spherical aberration. The control which corrects is performed. The information surface movement control unit 402 performs control to move the light beam spot to the target information surface with a predetermined spherical aberration.

  The predetermined spherical aberration is, for example, a spherical aberration that can secure a focus pull-in area where appropriate focus jump performance can be obtained. In other words, it is a spherical aberration that can secure a focus pull-in region that can appropriately reduce focus jump failure. The predetermined spherical aberration is, for example, a spherical aberration that provides a detection signal amplitude that can be focused. The information surface movement control unit 402 controls the optical disk device 400 that accesses the information carrier 102. The information surface movement control unit 402 controls the movement of the light beam spot to the target information surface with a predetermined spherical aberration, thereby affecting the influence of the surface shake and the interval variation of the information surfaces L0, L1, and L2. It is possible to suppress the focus jump failure and improve the focus jump performance.

  FIG. 12 is a diagram showing a schematic functional configuration of the optical disc apparatus 400 shown in FIG. The same components as those of the optical disc device 100 of the first embodiment described above are denoted by the same reference numerals as those in FIG. The optical disc apparatus 400 according to the second embodiment includes a converging unit 110, a spherical aberration changing unit 412, an inner / outer peripheral moving unit 112, a vertical moving unit 114, a focus detecting unit 116, a focus control unit 118, and an information surface movement. A control unit 120 and an information surface movement control unit 402 are provided. The configurations of the spherical aberration changing unit 412 and the information surface movement control unit 402 are different from the configuration of FIG.

  The spherical aberration changing unit 412 changes the spherical aberration of the light beam spot. For example, the spherical aberration changing unit 412 intentionally generates spherical aberration on the focused light beam spot. The information surface movement control unit 402 has the same configuration as the light beam spot movement control unit 104 in FIG. 2 and performs the same operation, but controls to perform a focus jump with a predetermined spherical aberration. Is different. The information surface movement control unit 402 controls the spherical aberration changing unit 412 to correct the spherical aberration, and to perform a focus jump while giving a predetermined spherical aberration to the target information surface.

  FIG. 13 is a diagram illustrating an example of a hardware configuration of the optical disc apparatus 400 illustrated in FIG. Note that the same components as those of the optical disc device 100 according to Embodiment 1 described above are denoted by the same reference numerals as those in FIG.

  The optical disk device 400 has a disk motor 140, an optical head device 420, a preamplifier 126, a focus actuator drive circuit 136, a transfer table 124, a transfer table drive circuit 134, and a focus error generator in the configuration shown in FIG. 128, a focus control unit 130, a microcomputer 428, a spherical aberration detector 422, a spherical aberration control unit 424, and a beam expander drive circuit 426. The configuration of the microcomputer 428, the spherical aberration detector 422, the spherical aberration control unit 424, and the beam expander drive circuit 426 is different from the configuration of FIG.

  The microcomputer 428 has the same configuration as the microcomputer 132 of the first embodiment and performs the same operation, but the part that controls the beam expander drive circuit 426 by the spherical aberration control unit 424 is different. The spherical aberration detector 422 receives the signal from the preamplifier 126 and detects the spherical aberration of the light beam spot. The microcomputer 428 (spherical aberration control unit 424) outputs a control signal based on the detection signal from the spherical aberration detector 422. The beam expander drive circuit 426 drives a spherical aberration correction actuator 432 (to be described later) of the optical head device 420 according to a control signal from the spherical aberration control unit 424 in the microcomputer 428. Here, the spherical aberration detector 422 may share at least a part of the circuit with the focus error generator 128, or may be a signal corresponding to a jitter or error rate indicating the quality of the reproduction signal. Depending on the configuration of the optical system or system, the amplitude of the tracking error signal or the RF amplitude can be substituted.

  FIG. 14 is a diagram showing a schematic configuration of the optical head device 420 shown in FIG. The same components as those of the optical head device 122 according to the first embodiment described above are denoted by the same reference numerals as those in FIG. The optical head device 420 has the same configuration as that of the optical head device 122 of the first embodiment and performs the same operation, but the part that changes the spherical aberration is different. The optical head device 420 includes a light source 146, an optical lens 142, a light receiving unit 144, a focus actuator 143, a spherical aberration correction lens 430, and a spherical aberration correction actuator 432.

  The spherical aberration correction lens 430 passes the light beam and changes the spherical aberration of the light beam spot. The spherical aberration correction lens 430 includes, for example, a concave lens and a convex lens. Instead of the spherical aberration correction lens 430, a liquid crystal plate that changes the transmittance on the inner and outer peripheral sides may be used. The spherical aberration correction actuator 432 moves the spherical aberration correction lens 430 to change the spherical aberration of the light beam spot.

  Note that the spherical aberration correction lens 430, the spherical aberration correction actuator 432, and the beam expander driving circuit 426 correspond to the spherical aberration changing unit 412 in FIG. Further, the microcomputer 428, the focus control unit 130, and the spherical aberration control unit 424 embody the information surface movement control unit 402 and the focus control unit 118 of FIG.

  With the above configuration, the operation of the second embodiment will be described with reference to FIGS. FIG. 15 is an explanatory diagram for explaining spherical aberration according to the second embodiment. In a state where the focus control is operating, the light beam emitted from the optical head device 420 is refracted by the protective film 152 of the information carrier 102. When the thickness of the protective film 152 varies, the light beam passing through the outer periphery of the lens is condensed at the focal point A, and the light beam passing through the inner peripheral side of the lens is condensed at the focal point B. The deviation between the focal point A and the focal point B is called spherical aberration.

  When spherical aberration does not occur on the information surfaces L0 to L2, the focal point of the outer peripheral side light beam coincides with the focal point of the inner peripheral side light beam (focal point C). When the spherical aberration is increased, the focal point A and the focal point B are separated from each other, the light beam spot is blurred as a whole, and the information surface is defocused. For example, when an optical lens having an NA of 0.8 or more is used, the optical disc apparatus 400 corrects spherical aberration in accordance with the information surfaces L0 to L2. This makes it possible to handle high-density information.

  FIG. 16 is an explanatory diagram for explaining a focus pullable range according to the second embodiment. 16A shows the movement of the optical lens in the vicinity of the information surface L0, FIG. 16B shows the waveform of the FE signal according to the movement of the optical lens, and FIG. 16C shows the movement of the optical lens. The waveform of the AS signal is shown.

  When the spherical aberration is corrected, the focus detection unit 116 obtains an FE signal and an AS (all light) signal as indicated by a solid line. As the light beam spot focused by the optical lens 142 approaches the information surface L0 from the protective film 152 side, the reflected light from the information surface L0 increases, so the FE signal has an amplitude from approximately 0 level to a negative polarity. It will increase. Also, the amplitude of the AS signal increases. The amplitude of the FE signal reaches a peak at point A1, and then decreases. When the light beam spot reaches the information surface L0, the amplitude of the FE signal becomes 0 level. On the other hand, the amplitude of the AS signal has a peak on the information plane L0.

  As the light beam spot leaves the information surface L0 and advances toward the substrate 150, the amplitude of the FE signal increases to a positive polarity. On the other hand, the amplitude of the AS signal decreases. The amplitude of the FE signal reaches a peak at the point B1, and then decreases. Thus, the FE signal has a waveform (S-shaped signal) that draws an S-shape around each of the information surfaces L0 to L2. The range in which the focus can be pulled into the target information surface is, for example, between the positive and negative peaks of the S-shaped signal (between points A1 and B1).

  On the other hand, when performing a focus jump with a predetermined spherical aberration, the focus detection unit 116 obtains an FE signal and an AS (all light) signal as shown by a dotted line in FIG. That is, the sigmoidal waveform of the FE signal and the waveform of the AS signal become gentle, and the positive and negative peaks (between points A2 and B2) of the S-shaped signal widen, and the range in which the focus can be pulled into the target information surface is widened. Thereby, the failure of the focus jump is reduced, and the performance of the focus jump can be improved. When spherical aberration is given, the AS signal peak may shift.

  Here, if the spherical aberration with respect to the target information surface is increased, the range in which the focus can be pulled in increases. On the other hand, the absolute value of the peak value of the FE signal decreases from L1 to L2. The information surface movement control unit 402 sets the spherical aberration at the time of focus jump so that focus pull-in is possible. For example, the information surface movement control unit 402 performs control so that the absolute value of the peak value L2 of the FE signal is higher than the absolute value of the focus pull-in level L3 that turns on the focus control.

  FIG. 17 is a flowchart showing a flow of focus jump control according to the second embodiment. The information surface movement control unit 402 performs a focus jump with a predetermined spherical aberration (S400). After the light beam spot is moved to the target information surface, control is performed so that the spherical aberration is corrected with respect to the target information surface (S402). Here, the information surface movement control unit 402 performs control to switch the spherical aberration so as to correspond to the target information surface.

  The information surface movement control unit 402 may start the spherical aberration switching control at or after the light beam spot reaches the target information surface. Alternatively, the spherical aberration switching control may be started before the light beam spot reaches the target information surface. Further, the information surface movement control unit 402 may start the spherical aberration switching control after starting the focus jump control. Alternatively, the spherical aberration switching control may be started simultaneously with or before the focus jump control is started.

  FIG. 18 is a timing chart showing a focus jump operation according to the second embodiment. Here, the movement from the information surface L2 to the information surface L0 will be described as an example. Other focus jumps such as movement from the information surface L1 to the information surface L0 operate in the same manner. The information surface movement control unit 402 outputs a focus jump control signal for controlling the focus jump to the vertical movement unit 114 via the information surface movement control unit 120. As a result, the light beam spot moves from the information surface L2 to the information surface L0. The focus jump control signal is, for example, a positive / negative pulse signal for acceleration / deceleration.

  At time S before starting the focus jump or after that, the information surface movement control unit 402 outputs a spherical aberration control signal for controlling the spherical aberration to the spherical aberration changing unit 412. As a result, the spherical aberration corresponding to the final target L0 is corrected in advance by passing through the information surface L1 on the way from L2 to L0.

  At or after time X when the spherical aberration corresponding to the next adjacent information surface L1 is corrected from the information surface L2, the information surface movement control unit 402 outputs a focus jump control signal and starts moving the light beam spot. Even after reaching the spherical aberration corresponding to the information surface L1, the spherical aberration control signal continues to be output and the correction of the spherical aberration is continued. Then, at the time point Y before the light beam spot reaches L0, the correction of the spherical aberration corresponding to the information surface L0 is completed. The movement of the light beam spot continues further in a state where the spherical aberration matches the target L0, and the focus jump is completed at the time Z when the LO is reached. Thereafter, depending on the amplitude of the tracking error signal and the read state of the address, a spherical aberration control signal may be output to slightly adjust the spherical aberration correction amount.

  FIG. 19 is a flowchart showing the flow of the light beam spot movement control according to the second embodiment in which the rotation of the disk motor, the movement between the layers, and the movement in the radial direction are integrated. This light beam spot movement control is performed when the light beam spot is moved from one information surface to another information surface and is moved in the inner peripheral direction or the outer direction of the optical disc. In this light beam spot movement control, the light beam spot movement control unit 104 first determines whether the movement is in the inner circumferential direction or the outer circumferential direction (S100). For example, when performing the focus jump, the light beam spot movement control unit 104 determines whether a desired information track on the target information surface is in the inner circumferential direction or the outer circumferential direction.

  If it is determined to move in the outer circumferential direction, in S202, the light beam spot movement control unit 104 gives a deceleration command to the rotation control unit 800, and in S106, the light beam spot movement control unit 104 causes the inner / outer circumferential movement unit 112 to Control is performed so that the beam spot moves in the outer circumferential direction to the target position. After moving in the outer circumferential direction, in S410, the spherical aberration is changed to a value corresponding to the target information surface. In step S102, the information surface movement control unit 120 controls the light beam spot to move to the target information surface. This movement time is about 10 ms for the movement of the light beam, about 100 ms for the confirmation of the address in the desired layer, and since spherical aberration is switched between the layers, it takes about 70 ms for the parallel processing, and about 180 ms. It becomes.

  Here, the black square line in FIG. 20A shows the time required for the optical head to move from the position of the innermost circumference r = 25 mm to the outermost circumference r = 58 mm, and is a diagram of the first embodiment. As in the case of 10, the position reached 58 mm after 180 ms. Further, the curve indicated by the ▲ point in FIG. 10A shows the response of the rotational speed of the disk motor. At this time, the disk motor 140 quickly decelerates from the innermost rotation speed of 1800 rpm, and when the optical head reaches 58 mm of the outermost periphery, the disk motor follows 1100 rpm and about 40% or more. Then, since the linear velocity is sufficiently high, there is no deterioration of the reproduction light. Further, while the optical head is positioned on the outermost periphery, the disk motor continues to decelerate to a predetermined rotational speed of 776 rpm. At the same time, in S102, the information surface movement control unit 120 causes the light beam spot to be the target information. Control to move to the surface. As described above, this movement time takes about 180 ms, and when moving to a desired information surface, the vehicle is decelerating to a target of approximately 776 rpm. After the focus jump, in S414, depending on the tracking error signal amplitude and address reading state, a spherical aberration control signal is output to slightly adjust the spherical aberration correction amount.

  On the other hand, when it is determined to move in the inner circumferential direction, in S200, the light beam spot movement control unit 104 gives an acceleration command to the rotation control unit 800, and in S410, the spherical aberration is changed to a value that is the target information surface. . In step S102, the information surface movement control unit 120 controls the light beam spot to move to the target information surface.

  The straight and dotted lines of the black squares in FIG. 10B indicate the time required for the optical head to move from the position of the outermost circumference r = 58 mm to the innermost circumference r = 25 mm. The dotted curve shows the response of the rotational speed of the disk motor at this time. After the acceleration command, the disk motor 140 quickly accelerates from the outermost rotation speed of 776 rpm, and follows up to 1100 pm when 180 ms elapses due to the movement of the target information surface by the information surface movement control unit 120. Since the speed changes in the fast direction, there is no possibility of deterioration of the reproduction light. After the focus jump, in S414, depending on the tracking error signal amplitude and address reading state, a spherical aberration control signal is output to slightly adjust the spherical aberration correction amount. After that, in S104, the inner / outer periphery moving unit 112 controls the light beam spot to move to the target position in the inner periphery direction. At this time, the disk motor continues to respond toward the innermost target rotation speed, and when the transfer table reaches 25 mm, it responds to approximately 1800 rpm, so the possibility of reproduction light deterioration is extremely low. As described above, according to the embodiment, since the spherical aberration is controlled when performing the focus jump, the movement time between layers is further increased, and the effect of the present invention is further increased.

  By performing the control as shown in the first and second embodiments, it is possible to efficiently suppress the deterioration of information due to the reproduction light, and to reduce the overhead by simultaneously rotating the spindle during the focus jump time. Thus, the access time between the total layers can be shortened.

  The light beam spot movement control unit of the present invention is used in various optical disk devices. Further, the optical disc apparatus of the present invention is widely used in industry as home appliances such as an optical disc recorder and OA equipment such as a data recording device.

The figure which shows the light beam spot movement control part which concerns on Embodiment 1 of this invention. The figure which shows schematic function structure of the optical disk apparatus shown in FIG. The figure which shows an example of the hardware constitutions of the optical disk apparatus shown in FIG. The figure which shows schematic structure of the optical head apparatus shown in FIG. The figure which shows the example of the information carrier shown in FIG. The figure which shows the structure of the recorded information in the information surface which concerns on Embodiment 1. FIG. Arrangement diagram of recording data of disc according to Embodiment 1 7 is a flowchart showing a flow of light beam spot movement control according to the first embodiment. Flowchart showing the flow of focus jump processing shown in FIG. Characteristic diagram showing response characteristics of a typical motor during access The figure which shows the light beam spot movement control part which concerns on Embodiment 2 of this invention. The figure which shows schematic structure of the optical disk apparatus based on Embodiment 2 of this invention. The figure which shows schematic function structure of the optical disk apparatus shown in FIG. The figure which shows an example of the hardware constitutions of the optical disk apparatus shown in FIG. The figure which shows schematic structure of the optical head apparatus shown in FIG. Explanatory drawing explaining the focus drawing possible range which concerns on Embodiment 2. FIG. A flowchart showing a flow of focus jump control according to the second embodiment. Timing chart showing focus jump operation according to the second embodiment 7 is a flowchart showing a flow of light beam spot movement control according to the second embodiment. Characteristic diagram showing response characteristics of a typical motor during access

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Optical disk apparatus 102,510 Information carrier 104,202 Light beam spot movement control part 110 Focusing part 112 Inner / outer periphery movement part 114 Vertical movement part 116 Focus detection part 118 Focus control part 120,402,502 Information surface movement control part 412 Spherical aberration Change unit 426 Beam expander drive circuit

Claims (2)

A light beam spot movement control device for performing control to move a light beam spot focused on the information surface of an optical disc having at least two information surfaces stacked and recording or reproducing at a substantially linear speed. ,
In the case where the light beam spot is moved from any one of the information surfaces to the other information surface, and the light beam spot is moved in the inner circumferential direction of the optical disc, the light beam spot is moved to the other information surface. After moving the beam spot, move the light beam spot in the inner circumferential direction,
When the light beam spot is moved from one of the information surfaces to the other information surface, and the light beam spot is moved in the outer circumferential direction of the optical disc, the light beam spot is moved in the outer circumferential direction. A light beam spot movement control apparatus that performs control to move the light beam spot to the other information surface after being moved. An optical disc apparatus for accessing an optical disc having at least two information planes stacked and an information track formed on the information plane and performing recording or reproduction at a substantially constant linear velocity,
Rotation control means for controlling the optical disk to rotate at a constant linear velocity by driving a motor;
Focusing means for focusing the light beam on the information surface of the optical disc;
Vertical moving means for moving the focusing means in a direction substantially perpendicular to the information surface;
Focus detection means for generating a signal corresponding to the focused state of the light beam on the information surface;
A focus control means for driving the vertical movement means in accordance with a signal from the focus detection means, and controlling the light beam on the information surface so as to have a substantially constant focusing state;
Information surface movement control means for performing control to move a light beam spot focused on any of the information surfaces to another information surface;
An inner and outer periphery moving means for moving the light beam spot in the inner peripheral direction or the outer peripheral direction of the optical disc ;
A light beam spot movement control means for performing control to move the light beam spot to any position of the information track,
The light beam spot movement control means includes:
In the case where the light beam spot is moved from one of the information surfaces to the other information surface, and the light beam spot is moved in the inner circumferential direction, the rotation speed of the motor is set by the rotation control means. Accelerate and move the light beam spot to the other information surface by the information surface movement control means, and then move the light beam spot in the inner peripheral direction by the inner and outer periphery movement means,
In the case where the light beam spot is moved from one of the information surfaces to the other information surface, and the light beam spot is moved in the outer circumferential direction, the rotation speed of the motor is reduced by the rotation control means. Then, after moving the light beam spot in the outer peripheral direction by the inner / outer peripheral movement means, the information surface movement control means performs control to move the light beam spot to the other information surface. An optical disc device characterized.

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