JP2006079768A - Optical reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical reproducing device capable of smoothly performing an optical head access operation by suppressing the optical head from being out of servo control in jump operation. <P>SOLUTION: Once the jump operation is started, it is decided at S101 which of the right side edge (R jump) and left side edge (L jump) of a converged beam is to be jumped. When the L jump is decided, the gain Gr of servo of an R driver 20b is increased at S102 to α times as large as a set value in normal operation. Then the servo of an L driver 20a is turned off at S103 and jump pulses and brake pulses are applied from the L driver 20a to a coil 205a for the left side edge to make an inter-layer jump (N-layer jump, where N is a natural number) at the left side edge. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical reproducing apparatus that reproduces information by making a flat beam incident on a recording medium in which a plurality of recording layers are arranged in the laminating direction from a direction perpendicular to the laminating direction. It is suitable for use in an optical reproducing apparatus that reproduces a card-type optical recording medium on which a hologram is laminated.

  As a reproducing apparatus for a card type optical recording medium in which a planar optical waveguide hologram is laminated, for example, an apparatus described in Patent Document 1 is known.

  Here, on the card type optical recording medium, a plurality of recording layers for holding predetermined information as a hologram pattern are laminated and arranged. When a beam is incident on a predetermined recording layer, the beam is scattered by the hologram pattern formed on the recording layer, and the scattered light is emitted from the upper surface or the lower surface of the card type optical recording medium. The emitted scattered light is received by an image pickup device such as a CCD (Charge Coupled Device), whereby the information held in the recording layer is reproduced.

  Such a reproducing apparatus is provided with an optical head for causing a flat beam to enter the beam entrance of the recording layer, and further, the optical head is adapted to correct a deviation in the stacking direction of the flat beam with respect to the recording layer. Actuators are deployed. By driving the actuator in accordance with an error signal corresponding to the amount of deviation in the stacking direction, the flat beam is positioned at the beam entrance of the recording layer to be reproduced.

When changing the recording layer to be reproduced, a drive signal is applied to the actuator to move the flat beam in the direction of the target recording layer. For example, the number of recording layers crossed during the movement is counted, and the actuator is stopped at the timing when the count value corresponding to the amount of movement to the target recording layer is reached. Thereby, the convergent beam can be positioned at the target recording layer position.
JP 2000-155960 A

  In such an optical reproducing apparatus, a drive mechanism for individually driving both side edges of the optical head is provided so that both side edges of the flat beam can be individually moved in the recording layer stacking direction. Therefore, when the flat beam is accessed in the stacking direction, both side edges of the optical head are individually driven by the respective driving mechanisms. In this case, the jump operation may be performed only on the other side edge in a state where the jump operation on one side edge is completed. At this time, the side edge on which the jump is completed is servoed by the corresponding drive mechanism, and is positioned so as not to be separated from the layer at the time of completion of the jump.

  However, when a jump is performed on the other side edge in this manner, the reaction force causes a displacement force to be applied to the side edge in the jump completed state, and vibration is generated at this side edge. FIG. 14 shows such vibration by the amplitude of the servo signal. In this figure, a jump is performed only at the left side edge of the optical head.

  At this time, the right side edge is controlled by the corresponding drive mechanism so that it does not come off the layer at the time of completion of the jump by applying the servo. However, if the influence of the jump on the left side edge appears greatly on the right side edge, the servo is lost, and the drawing position of the right side edge may flow to another layer. In this case, it is necessary to perform a processing operation such as performing the right side edge jump again to return the right side edge to the original layer.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical reproducing apparatus that can suppress servo detachment that occurs during a jump operation, thereby enabling smooth access operation of the optical head.

  In view of the above problems, the present invention has the following features.

  According to a first aspect of the present invention, there is provided an optical reproducing apparatus for reproducing information by making a flat beam incident on a recording medium in which a plurality of recording layers are arranged in the stacking direction from a direction perpendicular to the stacking direction. Servo means for correcting a positional deviation in the laminating direction of the flat beam with respect to the recording layer by individually displacing both side edges in the laminating direction, and scanning means for moving a width direction side edge of the flat beam in the laminating direction The servo means increases the gain of the servo in response to the scanning means moving the side edge in the width direction of the flat beam in the stacking direction.

  According to a second aspect of the present invention, in the optical reproducing apparatus according to the first aspect, when the servo means is moved in the stacking direction by the scanning means, one of the side edges in the width direction of the flat beam. The servo gain for the other side edge is increased.

  According to a third aspect of the present invention, in the optical regenerator according to the second aspect of the invention, the servo means sets the servo gain for the other side edge to the original gain in response to the end of the movement of the one side edge. It is made to return to.

According to a fourth aspect of the present invention, in the optical regenerator according to the second aspect, the servo means moves the other side edge at a timing when a predetermined time elapses after the servo pull-in to the one side edge starts. The servo gain is returned to the original gain.

  According to the present invention, the gain of the servo means is increased during the flat beam jump operation, so that the other side edge is not easily affected by the jump on one side edge. Servo slippage is less likely to occur at the edges. Thereby, the access operation of the optical head can be performed smoothly and quickly.

  Further, as in the third aspect of the invention, if the servo gain for the other side edge is returned to the original gain in response to the end of the movement of one side edge, the movement of one side edge is performed. It is possible to suppress the occurrence of servo slippage at the other side edge due to the reaction force due to.

  Further, as in the fourth aspect of the invention, the servo gain for the other side edge is returned to the original gain at the timing when a predetermined time has elapsed after the servo pull-in to the one side edge is started. For example, it is possible to suppress the minute vibration generated in one side edge from the start of servo pull-in to the end of servo pull-in from affecting the other side edge.

In addition, the effects and significance of the present invention will be further clarified by the following description of embodiments. However, the following embodiment is an embodiment of the present invention, and the meanings of the terms of the present invention or each constituent element are not limited to those described in the following embodiment.

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

  FIG. 1 is a top view of an optical card 100 according to an embodiment.

  The optical card 100 has a configuration in which a laminated structure in which a plurality of recording layers are laminated is included in a transparent substrate. Each recording layer is formed as a planar optical waveguide, and a hologram having a pattern corresponding to recording information is formed in the waveguide. Such a hologram is formed at a position corresponding to the data area 101 in the drawing.

  Each recording layer is recorded with address information 102 as address marks 102 indicating how many layers the recording layer corresponds to from the initial position. As shown in the figure, two sets of address marks 102 are arranged on the left and right of the data area 101, and the same address information is recorded in each set of address marks.

A set of address marks 102 is composed of seven areas, and a hologram is selectively formed in each of these areas in accordance with address information. That is, address information is held by a combination of a region where a hologram is formed and a region where a hologram is not formed. For example, if the area where the hologram is formed is set to “1” and the area where the hologram is not formed is set to “0” and the address is held in binary, the address mark 102 sets 0 to 2 ⁷ (= 128). ) Address can be assigned to each recording layer.

  In the optical regenerator described later, two sets of seven optical sensors are arranged so as to face these regions. Of each region, the scattered light is guided to the corresponding optical sensor from the region where the hologram is formed, and an electric signal is output. By detecting which optical sensor has output the electric signal, the address (recording layer number) of the recording layer on which the laser beam is incident is identified.

  Further, each recording layer is provided with a servo mark 103 for detecting a shift in the stacking direction of the incident laser light with respect to the recording layer. A hologram is formed in the arrangement area of the servo mark 103 as in the case of the address mark 102, and the incident beam is scattered by the hologram and guided to the corresponding sensor.

  As shown in the figure, the servo marks 103 are arranged on the left and right sides of the data area 101 so as to be located further on the side edge than the address marks 102. The arrangement positions of the servo marks 103 are set so as to be arranged on the left and right as viewed from the beam entrance side.

  Note that the address mark 102 and the servo mark 103 may be configured by forming a grating in the region in addition to the hologram as described above.

  FIG. 2 is a side view of the optical card 100 viewed from the beam entrance 104 side. As illustrated, the recording layer of the optical card 100 is formed by laminating a core 105 and a clad 106. The beam is incident on the core 105 and scattered by a hologram formed in the core 105. In the core 105, the data area 101, the address mark 102, and the servo mark 103 are arranged, and a hologram is formed.

  FIG. 3 is a diagram showing a beam incident state on the core 105. This figure shows a state when the optical card 100 is viewed from the beam incident side. Further, the servo mark is arranged further to the back than the entrance of the core 105 shown in FIG. In the figure, the arrangement of servo marks is indicated by dotted lines.

  At the time of reproduction, a step beam having a cross section as shown by a dotted line in FIG. Here, when the central portion a of the step beam is incident on the core 105 without misalignment in the stacking direction, the left and right step portions b1 and b2 are incident on the core 105 by substantially the same amount, and the left and right servo marks respectively. Are scattered by the same amount. Therefore, when the scattered light scattered by the servo mark at this time is received by a pair of optical sensors S1, S2, for example, as shown in FIG. 4, the output difference between the sensors S1, S2 becomes zero.

  On the other hand, when the central portion a of the step beam is shifted in the stacking direction with respect to the core, there is a difference between the light amount that the step portion b1 is incident on the core and the light amount that the step portion b2 is incident on the core. And there is a difference in the amount of light scattered by each servo mark. For this reason, the output difference between the sensors S1 and S2 does not become zero, but has positive and negative values according to the direction and magnitude of the deviation.

  By using the difference signal as an error signal and applying servo to both the left and right end portions of the optical head, the center portion a of the step beam can be positioned with respect to the core 105 without deviation in the stacking direction.

  5 and 6 show the configuration of the optical head 200. FIG. 5 is a top view, and FIG. 6 is a cross-sectional view taken along line A-A ′ of FIG. 5.

  The optical head 200 includes an optical system for causing laser light to enter the optical card and an actuator for adjusting the position of the laser light with respect to the recording layer.

  A support portion 202 is disposed on the chassis 201, and a lens holder 203 is attached to the support portion 202 via two sets of leaf springs 204. The lens holder 203 is equipped with a cylindrical lens 306 that converges the laser light into a flat beam and enters the recording layer. In addition, coils 205 a and 205 b wound in a predetermined direction are fixed to both ends of the lens holder 203.

  The cylindrical lens 306 has a curvature or refractive index adjusted so that the cross-sectional shape of the incident beam with respect to the core 105 has a step shape as shown in FIG.

  Furthermore, magnets 206a and 207a are arranged on the chassis 201 so as to sandwich the coil 205a. Similarly, magnets 206b and 207b are arranged so as to sandwich the coil 205b. When two magnets sandwiching each coil are used as a pair, the pair of magnets are arranged such that opposing surfaces sandwiching the coils have the same polarity. Therefore, when a current flows into each coil, an upward or downward driving force is generated in each coil. With this driving force, the left and right ends of the lens holder 203 are driven.

  In addition, the semiconductor laser 301 is disposed in the chassis 201 so that the long axis of the outgoing beam having an elliptical cross section is horizontal. Laser light emitted from the semiconductor laser 301 is converted into parallel light by the collimator 302. Then, it is expanded in the horizontal direction by the beam expander 303. Thereafter, the light is reflected upward by the mirror 304. Thereafter, the laser light is reflected to the side by the mirror 305 disposed on the lens holder 203. Then, the light is converged in the vertical direction by the cylindrical lens 306 and converged on the recording layer of the optical card 100 in a cross-sectional shape as shown in FIG.

  7 and 8 show the configuration of the apparatus main body to which the optical head 200 is mounted. FIG. 7 is a top view of the apparatus main body, and FIG. 8 is a sectional view taken along the line A-A ′.

  The optical head 200 is mounted on the base 401 such that the bottom surface of the chassis 201 is placed on the base 401. A frame 402 is planted on the base 401, and a pair of guides 403 that support the side edges of the optical card 100 are formed on the frame 402. The guide 403 is tapered at the front end thereof so that the optical card 100 can be easily inserted. The gap of the guide 403 is set to be larger than the thickness of the optical card 100 by a small amount.

  In addition, a CCD 404 is mounted on the frame 402 at a position facing the data area 101 on the lower surface side of the optical card 100. The beam scattered by the data area 101 and emitted from the lower surface of the optical card 100 is received by the CCD 404 and converted into an electrical signal. The converted electric signal is supplied to a reproducing circuit and reproduced into predetermined information.

  In the frame 402, seven photosensors 405a and 405b are arranged at positions facing the seven hologram forming regions constituting the set of address marks 102. Each of the optical sensors 405a and 405b receives the scattered light and outputs an electrical signal when a hologram is formed in the corresponding hologram forming region.

  Further, two optical sensors 406 a and 406 b are arranged on the frame 402 at positions facing two hologram forming areas constituting the set of servo marks 103. Each of the optical sensors 406a and 406b receives the scattered light from the corresponding hologram forming region and outputs an electrical signal.

  Of the beams converged by the cylindrical lens 306, the beam that has entered the core 105 is scattered by the data area 101, the two sets of address marks 102 and the two sets of servo marks 103 arranged in the core 105, and the optical card. The light is emitted from the lower surface of 100. Among these, the beam scattered by the hologram 101 is received by the CCD 404 as described above.

  The beams scattered by the two sets of address marks 102 are received by the optical sensors 405a and 405b as described above and converted into electrical signals. The converted electric signal is supplied to an address decoder and reproduced as address information (layer number). As described above, when the address information is held by the address mark 102 as a binary number (the area where the hologram is formed is “1” and the area where the hologram is not formed is “0”), the address decoder A 7-digit binary number is acquired from the presence / absence of an electrical signal from the sensors 405a and 405b, converted into a decimal number, and the address information (recording layer number) of the recording layer is reproduced.

  Further, the beams scattered by the two sets of servo marks 103 are received by the optical sensors 406a and 406b as described above and converted into electrical signals. Then, by taking the difference between the converted electric signals, as described above, the deviation in the stacking direction of the convergent beam with respect to the recording layer (core) is detected and corrected.

  FIG. 9 shows a configuration example of the optical regenerator according to the present embodiment.

  In the figure, reference numerals 10a and 10b denote error signal generation circuits that generate and output error signals by subtracting sensor outputs from the respective sensors constituting the optical sensors 406a and 406b, and reference numeral 20a denotes an error signal from the error signal generation circuit 10a. Accordingly, a servo signal for positioning the beam convergence position on the recording layer is generated, and after phase compensation is performed, an L driver 20b that supplies the servo signal to the coil 205a responds to the error signal from the error signal generation circuit 10b. An R driver that generates a servo signal for positioning the position on the recording layer and applies phase compensation to the coil 205b.

  30a is an L address decoder that generates address information from the detection output from the optical sensor 405a, 30b is an R address decoder that generates address information from the detection output from the optical sensor 405b, and 40 is a CCD reproduction signal from the CCD 404. A reproduction signal processing circuit 50 that processes and reproduces information is a controller that controls each unit.

  In addition to the servo operation, the L driver 20a and the R driver 20b provide bias signals for causing the left and right ends of the optical head 200 to scan or jump in the recording layer stacking direction in response to a command from the controller 50, respectively. To the corresponding coil 205a and coil 205b.

  FIG. 10 shows a processing flow when jumping each side edge of the convergent beam in the stacking direction. This processing flow is an example in which one of the side edges of the convergent beam is jumped.

  When the jump operation is started, it is determined in S101 whether the jump is to jump the right side edge of the convergent beam (R jump) or to jump the left side edge (L jump). The If it is determined that the jump is an L jump, the servo gain Gr of the R driver 20b is increased to α times the set value G0 during normal operation in S102. In S103, the servo of the L driver 20a is turned off, and a jump pulse and a brake pulse are applied from the L driver 20a to the coil 205a on the left side edge, and an interlayer jump (N layer jump: on the left side edge) is applied. N is a natural number).

  When the interlayer jump at the left side edge is finished (S104: YES), the servo pull-in operation in the L driver 20a is started, and the servo gain Gr of the R driver 20b is set to the set value G0 during normal operation accordingly. Returned to Specifically, after a brake pulse is applied from the L driver 20a to the coil 205a, servo pull-in is started by the L driver 20a (S104: YES), and the servo gain Gr of the R driver 20b is increased. The setting value G0 during normal operation is restored. Thus, the interlayer jump on the left side edge ends.

  On the other hand, if it is determined in S101 that the jump operation is an R jump, processing for performing an interlayer jump in the R driver 20b is executed in S106 to S109 while increasing the servo gain of the L driver 20a. The

  That is, after the servo gain Gl of the L driver 20a is increased to α times the set value G0 during normal operation (S106), the servo of the R driver 20b is turned off, and the coil on the right side edge from the R driver 20b. A jump pulse and a brake pulse are applied to 205b (S107). Then, when an interlayer jump (N layer jump: N is a natural number) is performed at the right side edge (S108: YES), the servo pull-in operation of the R driver 20b is started, and the servo of the L driver 20a is responded accordingly. Is returned to the set value G0 during normal operation. Specifically, after a brake pulse is applied from the R driver 20b to the coil 205b, servo pull-in is started by the R driver 20b (S108: YES), and the servo gain Gl of the L driver 20a is The setting value G0 during normal operation is restored. Thus, the interlayer jump on the right side edge ends.

  FIG. 11 shows the vibration generated at the right side edge when the interlayer jump is performed at the left side edge by the amplitude of the servo signal. FIG. 4A shows a case where the servo gain of the right side edge is higher than normal, and FIG. 4B shows a case where the servo gain of the right side edge is kept constant as usual. ing.

  As shown in FIG. 4A, when the interlayer jump is performed on one side edge and the servo gain of the other side edge is increased as in this embodiment, the interlayer on one side edge is increased. The effect of the jump is difficult to reach the other side edge. Therefore, it is difficult for the servo to come off at the other side edge, and a smooth interlayer jump operation can be performed.

  FIG. 12 shows a processing flow when the convergent beam is accessed to the target layer by using the processing flow of the interlayer jump shown in FIG. In the figure, S101 to S109 are the process flow of the interlayer jump of FIG.

  When the access operation to the target layer is started, first, in S201, a convergent beam drawing operation for the first layer of the optical card is performed. In this pull-in operation, for example, the output of the optical sensors 406a and 406b is monitored while the convergent beam is moved from the initial position further away from the first layer toward the first layer, and the output appears from the optical sensors 406a and 406b. This is done by turning on the servo of the L driver 20a or R driver 20b corresponding to the optical sensor 406a or 406b where the output appears at the timing.

  Thus, when the convergent beam drawing operation for the first layer is completed, in S202, it is selected which of the L driver 20a and the R driver 20b performs the interlayer jump. Here, when the L driver 20a is first selected, a processing flow that proceeds from S101 to S102 is set, so that the gain Gr of the R driver 20b is increased and the L driver 20a is increased as described with reference to FIG. Then, a process for performing an interlayer jump (for N layers) is executed.

  Thus, when an interlayer jump is performed by the L driver 20a in S101 to S105, the process proceeds from S203 to S202, and then a process for performing an interlayer jump is selected by the R driver 20b. As a result, the process flow from S101 to S106 is set, and the process of performing an interlayer jump (for N layers) in the R driver 20b is executed while increasing the gain Gl of the L driver 20a as described in FIG. Is done.

  Thereafter, similarly, the interlayer jump by the L driver 20a and the interlayer jump by the R driver 20b are alternately performed. When it is detected by reading the address of the target layer that the left and right side edges have been accessed by the target layer (S203: YES), the access operation is terminated.

  In S103 and S107, the number of jump layers in one interlayer jump may be appropriately changed according to the difference from the target layer. However, if the number of jump layers is increased too much, the tilt of the convergent beam with respect to the layers increases, which may cause problems such as the servo not being applied and the address being unreadable. Therefore, it is preferable to keep the number of jump layers within several layers.

  Further, when one of the side edges is drawn into the target layer as a result of alternately repeating the interlayer jump by the L driver 20a and the interlayer jump by the R driver 20b, the other side edge is drawn into the target layer thereafter. The jump between layers is repeated until At this time, in S202, the driver corresponding to the other side edge is continuously selected.

  As mentioned above, although embodiment which concerns on this invention was described, it cannot be overemphasized that this invention is not limited to this embodiment, and various changes are possible.

  For example, in the processing flow of the interlayer jump in the above-described embodiment, the timing at which the interlayer jump ends, that is, after a brake pulse is applied from the L driver 20a or R driver 20b to the coil 205a or 205b, the L driver 20a or R driver 20b. The servo gain Gr or Gl of the R driver 20b or L driver 20a is restored to the set value G0 during normal operation at the timing when the servo pull-in is started in FIG. The servo gain Gr or Gl of the R driver 20b or L driver 20a is normally operated at a timing when a certain time ΔT has elapsed after the servo pull-in is started by the 20a or R driver 20b (S110, S120: YES). Return to the set value G0 It may be caused. Here, the time ΔT may be set to a time (approximately several milliseconds) required from the start of servo pull-in to the end of servo pull-in.

  In this way, the jump time is delayed by the time ΔT, but on the other hand, the minute vibration generated at one side edge from the start of servo pull-in to the end of servo pull-in is suppressed from affecting the other side edge. The effect that it can be done can be produced.

In addition, the configuration of the optical system, the actuator, the recording medium, the cross-sectional shape of the beam used therefor, and the like are not limited to those shown in the above embodiment. The embodiment of the present invention can be appropriately modified in various ways within the scope of the technical idea shown in the claims.

Top view of optical card 100 according to an embodiment Side view of optical card 100 according to an embodiment The figure explaining the beam incident state which concerns on embodiment The figure explaining the generation method of the error signal concerning an embodiment Top view of optical head 200 according to an embodiment Sectional drawing of the optical head 200 which concerns on embodiment Top view of an optical reproducing apparatus main body according to an embodiment Sectional drawing of the optical reproducing apparatus main body which concerns on embodiment The figure which shows the circuit structure of the optical reproduction apparatus which concerns on embodiment Process flowchart at the time of interlayer jump according to the embodiment The figure which shows the influence of the vibration at the time of the interlayer jump which concerns on embodiment Process flowchart for access operation according to embodiment The figure which shows the improvement of the process flowchart at the time of the interlayer jump which concerns on embodiment The figure which shows the influence of the vibration at the time of the interlayer jump concerning a conventional example

Explanation of symbols

200 Optical Head 20a L Driver 20b R Driver 50 Controller

Claims (4)

In an optical reproducing apparatus for reproducing information by making a flat beam incident on a recording medium in which a plurality of recording layers are arranged in a stacking direction from a direction perpendicular to the stacking direction,
Servo means for correcting a positional deviation in the laminating direction of the flat beam with respect to the recording layer by individually displacing both side edges of the flat beam in the laminating direction;
Scanning means for moving a side edge in the width direction of the flat beam in the stacking direction,
The servo means increases the gain of the servo in response to the width direction side edge of the flat beam being moved in the stacking direction by the scanning means.
An optical regenerator. In claim 1,
The servo means increases the gain of the servo with respect to the other side edge when one side edge among the side edges in the width direction of the flat beam is moved in the stacking direction by the scanning means.
An optical regenerator. In claim 2,
In response to the end of the movement of the one side edge, the servo means returns the servo gain for the other side edge to the original gain.
An optical regenerator. In claim 2,
The servo means returns the servo gain for the other side edge to the original gain at a timing when a predetermined time has elapsed since the start of the servo pull-in to the one side edge.
An optical regenerator.

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