JP2011060351A - Optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk device which suppresses occurrence of a flaw in a flexible disk without causing increase in cost. <P>SOLUTION: The optical disk device 20 is provided with: a spindle motor 22 for rotatably driving the flexible disk 15; a stabilizer 55 provided opposite the recording surface of the flexible disk 15 so as to reduce surface wobbling while the flexible disk 15 rotates; two vibrators (52A and 52B) mounted to the stabilizer 55 to vibrate the stabilizer 55; and a CPU which causes each vibrator to operate when the rotating speed of the flexible disk 15 is lower than a predetermined rotating speed (such as 4,000 rpm). In this case, in a transitional state when the effect of the stabilizer 55 is not exerted such as when the rotation of the flexible disk 15 is started or stopped, it is possible to reduce the number of times of sliding between the flexible disk and the stabilizer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical disc device, and more particularly to an optical disc device that performs at least one of recording and reproduction of information on a flexible sheet-like optical disc.

  With the recent digitization of information, there is an increasing demand for a large capacity optical disc. Development of a flexible sheet-like optical disk is underway as an optical disk capable of high-density recording of information at low cost.

  For example, Patent Document 1 discloses that a flexible recording disk is fixed to a spindle and rotated, and a stabilizing plate that applies an aerodynamic force suppresses disk surface deflection of the flexible recording disk. In a recording / reproducing apparatus that records and / or reproduces information on a recording disk by scanning with a recording / reproducing head, the stabilizing plate is a flat plate that covers at least the recording area of the recording disk, and is stable with the spindle. A recording / reproducing apparatus including position adjusting means for adjusting the relative distance between the chemical conversion plates in the disk rotation axis direction is disclosed.

  In Patent Document 2, a rotatable flexible disk having at least one recording surface, a casing for rotatably accommodating the disk, and a predetermined standing wave pattern are induced when the flexible disk rotates in the casing. A disc cartridge is disclosed that includes a stabilizer that is arranged to maintain the flexible disk substantially in a predetermined standing wave pattern even when the recording head moves on the recording surface of the flexible disk.

  Patent Document 3 discloses an optical disk device that optically accesses an optical disk by rotating a flexible optical disk while the objective lens is disposed opposite to the optical disk, and in the vicinity of the objective lens when the optical disk rotates. The optical disc has a stabilizer that is brought close to either one surface or both surfaces of the optical disc, and the stabilizer has a convex surface that is elastically deformable with respect to the optical disc, and the facing surface covers and forms the opening of the hollow member. In addition, there is disclosed an optical disc apparatus configured so that the radius of curvature of the opposing surface can be changed by adjusting the internal pressure of the hollow member.

  By the way, in an optical disc apparatus that records or reproduces information with respect to a flexible optical disc (hereinafter abbreviated as “flexible disc” for the sake of convenience), this occurs when the flexible disc rotates. The air flow acts between the stabilizer and the flexible disk to suppress the deflection of the flexible disk.

  However, when the number of rotations of the flexible disk is low, such as when the rotation of the flexible disk starts and stops, the air flow is insufficient, so that the air force acting between the flexible disk and the stabilizer is insufficient. Is small.

  And since a flexible disk has low rigidity, if the surface blur suppression force by air does not work, it causes about 10 times larger surface blur than a normal optical disk.

  For this reason, when the rotational speed of the flexible disk is low, the flexible disk and the stabilizer slide, and the flexible disk may be damaged.

  In the recording / reproducing apparatus disclosed in Patent Document 1, the distance (gap) between the flexible disk and the stabilizer is made larger than a specified value by the position adjusting means when the rotation of the flexible disk starts and stops. Just do it. However, in this case, a mechanism for changing the gap with high accuracy by several millimeters or more is necessary, resulting in high cost. Further, there arises a disadvantage that the height of the recording / reproducing apparatus is increased.

  Further, in the disk cartridge disclosed in Patent Document 2, since a stable state in which a standing wave is generated is created only when the rotation of the flexible disk is stabilized, the rotation of the flexible disk is started and stopped. Sometimes sliding between the flexible disk and the stabilizer is unavoidable.

  Further, in the optical disk device disclosed in Patent Document 3, although the stabilizer is deformed even if the flexible disk collides with the stabilizer, the damage to the flexible disk is small, but the flexible disk and the stabilizer There is a risk that the flexible disk may be damaged when the stabilizer collides with dust or dirt that has entered the gap.

  The present invention has been made under such circumstances, and an object of the present invention is to provide an optical disc apparatus capable of suppressing the occurrence of scratches on a flexible disc without increasing the cost.

  The present invention relates to an optical disc apparatus that performs at least one of information reproduction and recording on a flexible sheet-like optical disc, and a rotation drive device that rotates the optical disc; and when the optical disc is rotating In order to reduce surface wobbling, an optical disc apparatus comprising: a stabilizing member provided opposite to the optical disc; and a vibration exciter that varies a gap between the optical disc and the stabilizing member.

  According to this, it is possible to suppress the occurrence of scratches on the flexible disk without increasing the cost.

1 is a diagram (part 1) illustrating a configuration of an optical disc device according to an embodiment of the present invention; It is FIG. (2) which shows the structure of the optical disk apparatus based on one Embodiment of this invention. FIG. 10 is a diagram for explaining an operation of a CPU when an optical disc apparatus receives a recording request or a reproduction request from a host device. It is a figure for demonstrating the cycle for a test. It is a figure for demonstrating the optical disk apparatus for a test. It is a figure for demonstrating a test result. It is a figure for demonstrating the modification of an optical disk device.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2 show a schematic configuration of an optical disc apparatus 20 according to an embodiment.

  The optical disc device 20 corresponds to a flexible disc, and includes a stabilizer 55, two vibrators (52A, 52B), a spindle motor 22 for rotating the flexible disc 15, an optical pickup device 23, and the optical disc device. Seek motor 21 for driving the pickup device 23 in the sledge direction, laser control circuit 24, encoder 25, drive control circuit 26, vibration control circuit 51, reproduction signal processing circuit 28, buffer RAM 34, buffer manager 37, interface 38, flash A memory 39, a CPU 40, a RAM 41, and the like are provided. Note that the arrows in FIG. 2 indicate the flow of typical signals and information, and do not represent the entire connection relationship of each block.

  The optical pickup device 23 is a device for condensing laser light on the recording layer of the flexible disk 15 and receiving reflected light from the flexible disk 15. The optical pickup device 23 includes a semiconductor laser, a coupling lens, an objective lens, a light receiver, and a drive system (focusing actuator and tracking actuator) for driving the objective lens. Here, as an example, the optical pickup device 23 complies with the Blu-ray Disc standard.

  The reproduction signal processing circuit 28 acquires a servo signal (such as a focus error signal and a track error signal), address information, synchronization information, and an RF signal based on the output signal of the optical pickup device 23. Here, as an example, the reproduction signal processing circuit 28 is compliant with the Blu-ray Disc standard.

  The servo signal obtained here is output to the drive control circuit 26, the address information is output to the CPU 40, and the synchronization signal is output to the encoder 25, the drive control circuit 26, and the like.

  Further, the reproduction signal processing circuit 28 performs a decoding process and an error detection process on the RF signal. When an error is detected, the reproduction signal processing circuit 28 performs an error correction process and then stores the reproduction data in the buffer RAM 34 via the buffer manager 37. Store. The address information included in the reproduction data is output to the CPU 40.

  Based on the track error signal from the reproduction signal processing circuit 28, the drive control circuit 26 generates a tracking actuator drive signal for correcting the positional deviation of the objective lens in the tracking direction.

  The drive control circuit 26 generates a focusing actuator drive signal for correcting the focus shift of the objective lens based on the focus error signal from the reproduction signal processing circuit 28. The drive signals for the actuators generated here are output to the optical pickup device 23. Thereby, tracking control and focus control are performed.

  Furthermore, the drive control circuit 26 generates a drive signal for driving the seek motor 21 and a drive signal for driving the spindle motor 22 based on an instruction from the CPU 40. The drive signal of each motor is output to the seek motor 21 and the spindle motor 22, respectively.

  The buffer RAM 34 temporarily stores data to be recorded on the flexible disk 15 (recording data), data reproduced from the flexible disk 15 (reproduction data), and the like. Data input / output to / from the buffer RAM 34 is managed by a buffer manager 37.

  Based on an instruction from the CPU 40, the encoder 25 takes out the recording data stored in the buffer RAM 34 via the buffer manager 37, modulates the data, adds an error correction code, etc. Generate a write signal. The write signal generated here is output to the laser control circuit 24.

  The laser control circuit 24 controls the light emission power of the semiconductor laser. For example, during recording, a laser control circuit 24 generates a drive signal for the semiconductor laser based on the write signal, the recording conditions, the light emission characteristics of the semiconductor laser, and the like.

  The interface 38 is a bidirectional communication interface with the host device 90 (for example, a personal computer) and conforms to standard interfaces such as ATAPI (AT Attachment Packet Interface), SCSI (Small Computer System Interface), and USB (Universal Serial Bus). is doing.

  The flash memory 39 stores various programs described by codes readable by the CPU 40, recording conditions including recording power and recording strategy information, and emission characteristics of the semiconductor laser.

  The CPU 40 controls the operation of each unit in accordance with the program stored in the flash memory 39 and saves data necessary for control in the RAM 41 and the buffer RAM 34.

  The stabilizer 55 applies an aerodynamic force when the flexible disk 15 is rotating, and suppresses surface deflection of the flexible disk 15.

  When the flexible disk 15 is set on a turntable (not shown), the gap (gap) between the flexible disk 15 and the stabilizer 55 is adjusted in advance to be 0.1 mm.

  Each vibrator is arranged between the chassis and the stabilizer 55 and vibrates the stabilizer 55. Here, each vibrator has a rod-shaped super magnetostrictive element having a length of 10 mm having a characteristic that the dimension changes by about 1000 ppm in a magnetic field of 1 kOe, and a coil disposed around the super magnetostrictive element. Therefore, when a current is passed through the coil so that a magnetic field of 1 kOe is generated in the giant magnetostrictive element, the total length of the giant magnetostrictive element changes by 10 μm. If an alternating magnetic field is applied to the giant magnetostrictive element, the giant magnetostrictive element can be vibrated.

  The vibration control circuit 51 generates a drive signal for driving each vibrator based on an instruction from the CPU 40. The drive signal generated here is output to the vibrators 52A and 52B.

  Next, processing in the optical disc device 20 when a request for recording or reproduction with respect to the flexible disc 15 is issued from the host device 90 will be briefly described with reference to FIG. The flowchart in FIG. 3 corresponds to a series of processing algorithms executed by the CPU 40.

  When a recording request command or a reproduction request command (hereinafter, collectively referred to as “request command” for convenience) is received from the host device 90, the start address of the program corresponding to the flowchart of FIG. 3 is set in the program counter of the CPU 40, and processing is performed. Start.

  In the first step S401, the vibrator 52A and the vibrator 52B are driven via the vibration control circuit 51. Here, the stabilizer 55 is vibrated at a frequency of 300 Hz and an amplitude of 2 μm. As a result, a positive pressure is generated in the gap (gap) between the flexible disk 15 and the stabilizer 55. In this case, since the flexible disk is soft, the gap at the innermost peripheral portion being clamped is 0.1 mm, but the distance between the flexible disk 15 and the stabilizer 55 increases toward the outer periphery.

  In the next step S403, rotation of the spindle motor 22 is started via the drive control circuit 26. At this time, the reproduction signal processing circuit 28 is notified that the request command has been received from the host device 90.

  The rotational speed of the spindle motor 22 gradually increases.

  In the next step S405, the drive control circuit 26 is instructed to form a light spot near the target position corresponding to the designated address. Thereby, a seek operation is performed. If the seek operation is unnecessary, the process here is skipped.

  In the next step S407, it is determined whether or not the rotational speed of the spindle motor 22 is 4000 rpm or more. If the number of revolutions of the spindle motor 22 is less than 4000 rpm, the determination here is denied and the apparatus waits. That is, the stabilizer 55 remains in the excited state.

  On the other hand, if the rotation speed of the spindle motor 22 is 4000 rpm or more, the determination here is affirmed and the process proceeds to step S409.

  In step S409, the vibrator 52A and the vibrator 52B are stopped via the vibration control circuit 51. The reason for stopping the vibration to the stabilizer 55 is that the 300 Hz vibration due to the vibration remains as the vibration of the flexible disk 15 and adversely affects the focus control.

  In the next step S411, it is determined whether or not the rotational speed of the spindle motor 22 is 15000 rpm or more. If the number of revolutions of the spindle motor 22 is less than 15000 rpm, the determination here is denied and the apparatus waits. On the other hand, if the rotation speed of the spindle motor 22 is 15000 rpm or more, the determination here is affirmed and the process proceeds to step S413.

  In step S413, recording or reproduction is permitted according to the request command.

  In the next step S415, it is determined whether recording or reproduction is completed. If it is not completed, the determination here is denied and the determination is made again after a predetermined time has elapsed. If completed, the determination here is affirmed, and the routine goes to Step S417.

  In step S417, the rotation of the spindle motor 22 is decelerated via the drive control circuit 26.

  In the next step S419, it is determined whether or not the rotational speed of the spindle motor 22 is 4000 rpm or less. If the rotation speed of the spindle motor 22 exceeds 4000 rpm, the determination here is denied and the apparatus waits. On the other hand, if the rotation speed of the spindle motor 22 is 4000 rpm or less, the determination here is affirmed and the process proceeds to step S421.

  In this step S421, the vibration exciter 52A and the vibration exciter 52B are driven via the vibration control circuit 51.

  In the next step S423, it is determined whether or not the rotation of the spindle motor 22 is stopped. If the rotation of the spindle motor 22 is not stopped, the determination here is denied and the process waits. On the other hand, if the rotation of the spindle motor 22 is stopped, the determination here is affirmed and the process proceeds to step S425.

  In step S425, the vibration exciter 52A and the vibration exciter 52B are stopped via the vibration control circuit 51. Then, the process ends.

  Next, an experiment for knowing the effect of vibration on the stabilizer 55 was performed.

  Here, with respect to the rotation of the spindle motor 22, as shown in FIG. 4, (1) the rotation is held at 0 for 2 seconds, (2) the rotation is accelerated to reach 4000 rpm in 0.5 seconds, and (3) 4000 rpm. Held for 2 seconds, (4) accelerated to reach 15000 rpm in 0.5 seconds, (5) held for 10 seconds at 15000 rpm, (6) decelerated to 4000 rpm in 0.5 seconds, (7 The rotation schedule consisting of 18 seconds, which was held at 4000 rpm for 2 seconds, (8) decelerated to stop at 0.5 seconds, and (9) stopped, was taken as one cycle.

  The flexible disk used in the experiment was obtained by forming an aluminum film having a thickness of 100 nm by sputtering on the entire surface of one side of a polycarbonate film having an outer diameter of 120 mm, an inner diameter of 15 mm, and a thickness of 100 μm. And the aluminum film-forming surface was made into the stabilizer side. In this case, the aluminum film-forming surface is damaged when it is slid, so that it can be easily seen visually.

  When the 1000-cycle repetitive operation was continuously performed using the optical disc apparatus 20 of the present embodiment, there was no visually recognized scratch on the aluminum film-formed surface.

  On the other hand, as a comparative example, when the above 1000 cycles were repeated continuously without vibrating the stabilizer, sliding flaws were visually observed on the aluminum film-formed surface. In particular, when the distance from the center is outside 59 mm, it is in a transparent state, and the aluminum film is not scraped off. This causes dust generation due to sliding, causes contamination of the light incident surface of the flexible disc, and contamination of the surface of the objective lens in the optical pickup device, and hinders long-term stable operation of the optical disc device.

  Next, in order to know the state of sliding in detail, the number of times of sliding was measured using the experimental system shown in FIG.

  Here, the flexible disk used for measurement has a conductive aluminum film formed on the entire surface on the side of the stabilizer, and has conductivity. The spindle head turntable and clamper are also made of metal so that the spindle shaft and the surface of the flexible disk are electrically connected. Therefore, if a potential is applied between the flexible disk and the stabilizer, conduction occurs during sliding, and a voltage pulse is generated across the resistor. Here, this voltage pulse is measured.

  Then, the number of voltage pulses per cycle was counted while changing the excitation amplitude to the stabilizer. The measurement result is shown in FIG. The excitation amplitude can be changed by adjusting the magnitude of the current supplied to the vibrator.

  According to this, the excitation effect is obtained from an excitation amplitude of 0.5 μm. Further, at the excitation amplitude of 2 μm in the present embodiment, the frequency of sliding is a little less than 1/3 that when there is no excitation.

  As described above, by vibrating the stabilizer, the frequency of occurrence of sliding is greatly reduced, although it is not completely zero.

  By the way, in the experiment which measures the said voltage pulse, only the frequency | count of sliding is counted and the strength of sliding cannot be expressed. In this embodiment, no sliding scratches were observed on the surface of the flexible disk, but this did not mean that sliding did not occur at all. This was due to a decrease in the number of sliding times and a decrease in sliding strength. it is conceivable that.

  Subsequently, a guide groove similar to a Blu-ray disc is formed with an ultraviolet curable resin in a film having the same diameter and the same thickness as the flexible disc for sliding test on which the aluminum film is formed, and a bismuth oxide-based disc. A write-once recording material was sputtered and an ultraviolet curable resin was applied to the surface of 5 μm to prepare a flexible disk as a protective film. This flexible disc is compatible with the Blu-ray disc in optical and signal formats.

This flexible disk was set in the optical disk device 20 of the present embodiment, and a video signal was recorded in exactly the same format as the Blu-ray disk. Then, the above 1000-cycle repeated operation was continuously performed. Then, the video signal recorded on the flexible disk was reproduced, and the symbol error rate (SER) at that time was obtained. As a result, the obtained SER was less than 2 × 10 ⁻⁴ and was almost the same as the SER immediately after recording. In addition, if SER is less than 2 * 10 < ^-4 >, there is no problem in practical use.

In addition, when the SER was obtained after repeating the above 1000 cycles without vibrating the stabilizer, there was a portion where the SER exceeded 2 × 10 ⁻⁴ in the vicinity of the outer periphery.

  As described above, by oscillating the stabilizer, there is an effect that the sliding of the flexible disk and the stabilizer can be reduced in a transient state such as start and stop of rotation, and reading errors due to this can be suppressed.

  As is clear from the above description, in the optical disc device 20 according to the present embodiment, the spindle motor 22 constitutes the rotational drive device of the present invention, and the stabilizer 55 constitutes the stabilization member of the present invention.

  Further, the control device of the present invention is constituted by the CPU 40.

  It should be noted that at least a part of the processing according to the program by the CPU 40 may be configured by hardware, or all may be configured by hardware.

  As described above, according to the optical disc apparatus 20 according to the present embodiment, the spindle motor 22 for rotating the flexible disc 15 corresponds to the flexible sheet-like optical disc (flexible disc). In order to stabilize the deflection of the flexible disk 15 driven by the spindle motor 22 in the rotational axis direction, a stabilizer 55 installed on the opposite side of the recording surface of the flexible disk 15 is attached to the stabilizer 55. And two vibrators (52A, 52B) for vibrating the stabilizer 55, and a CPU 40 for operating the vibrators when the rotational speed of the flexible disk 15 is less than 4000 rpm. In this case, sliding between the flexible disk and the stabilizer can be reduced in a transient state such as start and stop of rotation.

  Therefore, it is possible to prevent the flexible disk from being damaged without increasing the cost.

  In addition, since the number of times of sliding between the flexible disk and the stabilizer is reduced, generation of dust due to sliding can be suppressed. As a result, contamination of the light incident surface in the flexible disk and contamination of the surface of the objective lens in the optical pickup device are suppressed, and it is possible to ensure stable long-term operation of the optical disk device. Therefore, the life of the optical disk device is extended, and the generation of dust can be reduced. As a result, it is possible to suppress an increase in environmental load with respect to the amount of resource mining and the amount of plastic waste discharged.

  In addition, although the said embodiment demonstrated the case where the vibrator was arrange | positioned between the chassis and the stabilizer 55, it is not limited to this. For example, as shown in FIG. 7, the spindle motor 22 may be attached to the housing via the vibrator 52. In this case, the spindle motor 22 vibrates up and down by the vibrator 52. The stabilizer 55 is fixed to the housing with a fixed leg. Therefore, the gap (gap) between the flexible disk 15 and the stabilizer 55 is changed by the vertical vibration of the spindle motor 22.

  Further, in the above embodiment, the exciter has a super magnetostrictive element and a coil disposed around the super magnetostrictive element, and an alternating current having a current value and frequency corresponding to the necessary vibration frequency and vibration amplitude is used as the coil. Although the case where it supplies is demonstrated, it is not limited to this. In short, it is sufficient that vibrations having a necessary frequency and amplitude are transmitted to the stabilizer 55 or the spindle motor 22.

  Moreover, although the said embodiment demonstrated the case where the stabilizer 55 was vibrated with a frequency of 300 Hz and an amplitude of 2 micrometers, it is not limited to this. For example, an appropriate frequency and amplitude can be set according to the size and material of the flexible disk 15, the shape of the stabilizer 55, the number of rotations of the spindle motor 22, the size of the gap at rest.

  Moreover, although the said embodiment demonstrated the case where CPU40 operates each vibrator when the rotation speed of the flexible disk 15 is smaller than 4000 rpm, it is not limited to this. For example, when focus control is performed after the rotational speed of the flexible disk 15 reaches around 15000 rpm, each vibrator may be operated even if the rotational speed exceeds 4000 rpm. However, in this case, the time required for access becomes slightly longer. Therefore, the number of rotations of the flexible disk 15 when operating each vibrator may be determined in consideration of the number of sliding times. Then, the determined rotational speed may be notified from the host device 90 to the CPU 40.

  As described above, the optical disc apparatus 20 of the present invention is suitable for suppressing the damage to the flexible disc without increasing the cost.

  DESCRIPTION OF SYMBOLS 15 ... Flexible disk, 20 ... Optical disk apparatus, 22 ... Spindle motor (rotation drive device), 40 ... CPU (control apparatus), 52A, 52B ... Vibrator, 55 ... Stabilizer (stabilization member).

JP 2006-107699 A JP-T-2001-520788 Japanese Patent No. 4205680

Claims (4)

An optical disc apparatus that performs at least one of reproduction and recording of information on a flexible sheet-like optical disc,
A rotation drive device for rotating the optical disc;
A stabilizing member provided opposite to the optical disk to reduce surface deflection when the optical disk is rotating;
An optical disk device comprising: a vibration exciter that varies a gap between the optical disk and the stabilizing member.   The optical disk apparatus according to claim 1, wherein the vibrator vibrates the rotation driving device or the stabilizing member.   3. The optical disc apparatus according to claim 1, further comprising a control device that operates the vibration exciter when a rotation speed of the optical disk is smaller than a predetermined rotation speed.   4. The optical disc apparatus according to claim 3, wherein the control device operates the vibration exciter when the optical disc starts rotating or when the optical disc stops rotating.

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