JP2004039140A - Optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an optical disk from resonating to the vibration of a fan. <P>SOLUTION: When an optical disk dimension detection part 21 judges the type of the optical disk, an arithmetic unit 22 reads the natural frequency of the optical disk of the judged type from a memory and rotationally drives the fan 24 so that a frequency of a vibration generated by the fan does not match the natural frequency of the optical disk. Thus, the optical disk 12 is prevented from resonating and a servo of an objective lens actuator 19 is stabilized. Tracking on the optical disk 12 by a laser beam from an objective lens 17 is satisfactorily maintained, and recording/playback of the optical disk 12 can always satisfactorily be performed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical disk device that performs recording and reproduction of an optical disk, and more particularly, to an optical disk device including a fan for ventilation.
[0002]
[Prior art]
Examples of the optical disk include a read-only compact disk (CD), a write-once compact disk recordable (CD-R), and a rewritable phase change disk (CD-RW). Such an optical disk has a signal recording surface, and a digital signal based on an audio signal or other data is recorded as bits on the signal recording surface.
[0003]
FIG. 3 shows a schematic configuration of an optical pickup device in an optical disk device that performs recording and reproduction of an optical disk. In the optical pickup device 101, a laser beam is emitted from a semiconductor laser 103 at the same time as the optical disk 102 is driven to rotate, and the laser beam is converted into a parallel beam by a collimating lens 104 and reflected by a mirror 105. The laser beam is condensed on the signal recording surface of the optical disk 102 through 106, and the laser light reflected on the optical disk 102 is guided to a photodetector (not shown) through the objective lens 106. The objective lens 106 is held by a lens holder 107, and the lens holder 107 is supported by an objective lens actuator 108. Further, the semiconductor laser 103, the collimating lens 104, the mirror 105, and the objective lens actuator 108 are accommodated in a housing 109 of the frame.
[0004]
The optical disk 102 is placed on a turntable, and is rotated by a spindle motor together with the turntable. The direction of the axis of rotation of the spindle motor and the direction of the normal to the surface of the turntable do not exactly coincide due to mechanical tolerances and are mutually inclined. Due to the tilt and the warp of the optical disc 102, a run-out occurs on the optical disc 102 on the turntable that is rotated. Also, it is difficult to accurately match the rotation center of the spindle motor with the track center of the optical disk 102, and the optical disk 102 is eccentric due to dimensional tolerances, so that the optical disk 102 has a track deflection. For this purpose, the objective lens actuator 108 includes a focus actuator for causing the depth of focus of the laser beam to follow the surface shake of the optical disc 102 and a tracking actuator for causing the focal position to follow the track shake of the optical disc 102. .
[0005]
Further, if the objective lens 106 is to only follow the surface runout or track runout of the optical disk 102, the servo band of the objective lens actuator 108 need only be as close as possible to the rotation speed of the optical disk 102. As a result, the servo band extends to a higher frequency range. In addition, in order to realize seamless recording and reproduction of moving images in recent years, it is necessary to increase the data transfer rate, and accordingly, it is necessary to increase the rotational angular velocity or rotational linear velocity of the optical disc 102, The servo band of the objective lens actuator 108 tends to reach a higher frequency range.
[0006]
On the other hand, optical disc devices are becoming smaller and lighter, and the temperature inside the device is more likely to rise, and the frequency of deterioration and breakage of the semiconductor laser 103 is increasing. In order to prevent this, a fan for ventilating the inside of the device is required. Further, various techniques have been proposed for performing efficient ventilation in the optical disk device by proper driving control of the fan.
[0007]
For example, in Japanese Patent Application Laid-Open No. 1-315096 (hereinafter referred to as Conventional Example 1), fan drive information corresponding to a temperature change in the apparatus is stored in advance, and fan drive information corresponding to a temperature detected by a temperature sensor is stored. There is disclosed a technique of controlling the air flow of a fan based on the read fan drive information to thereby suppress a rise in temperature inside the apparatus.
[0008]
Japanese Patent Application Laid-Open No. 2000-36188 (hereinafter referred to as Conventional Example 2) discloses that the rotation speed of a fan is controlled so as to be proportional to the rotation speed of a spindle motor for rotating an optical disk, thereby efficiently cooling the disk. Is disclosed.
[0009]
Further, Japanese Patent Application Laid-Open No. 5-258550 (hereinafter referred to as Conventional Example 3) discloses that the rotation of a spindle motor is transmitted to a fan, thereby not only cooling the inside of the apparatus but also making effective use of the rotation of the spindle motor. Thus, there is disclosed a technology for improving energy use efficiency.
[0010]
Also, Japanese Patent Application Laid-Open Nos. 9-134578 and 9-167389 (hereinafter referred to as Conventional Example 4) particularly relate to a CAV (Constant Angular Velocity) type optical disk device, and particularly to a line between an inner circumference and an outer circumference of an optical disk. Since the flying height of the floating head relative to the optical disk fluctuates due to the speed difference, the rotation of the fan is controlled in accordance with the linear velocity of the optical disk at the position of the floating head to adjust the wind pressure acting on the floating head. A technique has been disclosed in which the flying height of the flying head is maintained substantially constant by making a precise adjustment.
[0011]
[Problems to be solved by the invention]
By the way, when the fan is driven to rotate, mechanical vibration is generated. For example, the bearing of the motor may vibrate, and the bracket of the fan may resonate. For this reason, the vibration of the motor is normally cut off by interposing an anti-vibration rubber between the motor and the bracket. In addition, a change in air pressure occurs due to the wind cut off by the fan, and the inside of the optical disk device vibrates due to the change in air pressure. The frequency of this vibration has a component equal to an integral multiple of the product of the number of blades and the number of revolutions of the fan as a fundamental frequency.
[0012]
It is extremely difficult to completely suppress the vibration generated by such a fan, and the vibration may cause the optical disk to resonate, causing the optical disk to vibrate greatly. In a state where the optical disk is vibrated, the servo of the objective lens actuator 108 is not stabilized, and the laser beam from the objective lens 106 cannot accurately follow the optical disk 102, which adversely affects the recording and reproduction of the optical disk 102.
[0013]
When controlling the rotation speed of the fan as in each of the conventional examples 1 to 4, the frequency of the vibration generated by the fan fluctuates, so that the frequency of the vibration generated by the fan may coincide with the natural frequency of the optical disc. At this time, the optical disk resonated, and the quality of recording and reproduction of the optical disk was significantly deteriorated. More specifically, if the product of the number of blades and the number of revolutions of the fan as described above is used as the fundamental frequency, vibrations of an integral multiple of the frequency occur, and these frequencies become the natural frequency of the optical disk. At this time, the optical disk resonated at this time, and the quality of recording / reproduction of the optical disk deteriorated.
[0014]
For example, when controlling the amount of air blown by the fan as in Conventional Example 1, the rotation speed of the fan is changed. For this reason, the frequency of the vibration generated by the fan sometimes coincides with the natural frequency of the optical disk, and the optical disk resonated, and the quality of recording and reproduction of the optical disk was significantly deteriorated.
[0015]
Also, when the rotation speed of the fan is controlled so as to be proportional to the rotation speed of the spindle motor as in Conventional Example 2, the frequency of the vibration generated by the fan sometimes coincides with the natural frequency of the optical disk.
[0016]
Further, when the rotation of the spindle motor is transmitted to the fan as in Conventional Example 3, the rotation speed of the spindle motor is variable. For this reason, the frequency of the vibration generated by the fan sometimes coincides with the natural frequency of the optical disk.
[0017]
Also, when the rotation of the fan is controlled in accordance with the linear velocity of the optical disk at the position of the floating head as in Conventional Example 4, the frequency of the vibration generated by the fan may coincide with the natural frequency of the optical disk. .
[0018]
Therefore, the present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide an optical disk device in which an optical disk does not resonate due to vibration generated by a fan.
[0019]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides an optical disc device having an optical pickup device that irradiates a laser beam onto an optical disc through an objective lens while rotating the optical disc, and detects laser light reflected by the optical disc, A fan for ventilating the inside of the optical disk device; and control means for controlling the number of rotations of the fan such that an integral multiple of a fundamental frequency corresponding to the number of rotations of the fan deviates from the natural frequency of the optical disk.
[0020]
According to the present invention having such a configuration, the fan is controlled so that a value that is an integral multiple of the fundamental frequency corresponding to the rotation speed of the fan (corresponding to the frequency of vibration generated by the fan) deviates from the natural frequency of the optical disk. Is controlled. Therefore, the frequency of the vibration generated by the fan does not match the natural frequency of the optical disk, and the optical disk does not resonate. As a result, the servo of the objective lens actuator is stabilized, the tracking of the optical disk by the laser light from the objective lens is maintained well, and the recording and reproduction of the optical disk are always performed well.
[0021]
Further, in the present invention, there is provided detection means for detecting the type of the optical disk, and the control means comprises a fan for controlling the fan so that a value of an integral multiple of the fundamental frequency deviates from the natural frequency of the type of optical disk detected by the detection means. Is controlled.
[0022]
Here, since the natural frequency of the optical disk differs depending on the type of the optical disk, the type of the optical disk is detected, and the rotation frequency of the fan is adjusted so that the frequency of the fan deviates from the natural frequency of the detected type of optical disk. Controlling. Accordingly, it is possible to prevent resonance of the optical disk even when any of various optical disks is driven to rotate.
[0023]
As the method of detecting the type of the optical disk, for example, a method of detecting the shape and dimensions of the optical disk itself, a method of detecting the shape and dimensions of the cartridge containing the optical disk, and data for determining the type of the optical disk are stored in the optical disk. There is a method of reading from a document.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0025]
FIG. 1 is a block diagram showing an embodiment of the optical disk device of the present invention. In the optical disc device of the present embodiment, the optical disc rotating unit 11 includes a turntable (not shown) on which the optical disc 12 is placed, and a spindle motor (not shown) for driving the turntable to rotate. The optical disk 12 is rotated together with the turntable. The rotation control unit 13 controls the rotation speed of the spindle motor of the optical disk rotation unit 11 so that the linear rotation speed of the track of the optical disk 12 being followed is constant. This is called a CLV method.
[0026]
The semiconductor laser 14 emits a laser beam. This laser light is collimated by the collimating lens 15, reflected by the mirror 16, condensed on the signal recording surface of the optical disk 12 through the objective lens 17, further reflected by the optical disk 12, and passed through the objective lens 17 in a special optical path. Is guided to a photodetector (not shown). The objective lens 17 is held by a lens holder 18, and the lens holder 18 is supported by an objective lens actuator 19. The objective lens actuator 19 includes a focus actuator for causing the depth of focus of the laser beam to follow the surface deflection of the optical disc 12, and a tracking actuator for causing the objective lens 17 to follow the track deflection of the optical disc 12. The laser beam from the optical disk 12 is focused on a track of the optical disk 12 and follows the track.
[0027]
On the other hand, the optical disk size detection unit 21 detects the size of the optical disk placed on the turntable, and determines the type of the optical disk based on the detected size. Here, it is assumed that two types of optical disks A and B having different sizes from each other are selectively mounted on the turntable, and which of the two types of optical disks on the turntable is detected by the optical disk size detection. The determination is made by the unit 21. The optical disc A and the optical disc B have, for example, natural frequency characteristics as shown in the graph of FIG. As is clear from this graph, the gain of the optical disc A is high at each of the natural frequencies fA1 and fA2. Similarly, the gain of the optical disc B is high at each of the natural frequencies fB1 and fB2. The vibration mode of the optical disk at the natural frequencies fA1 and fB1 is primary in the radial direction and primary in the circumferential direction. The vibration mode of the optical disk at the natural frequencies fA2 and fB2 is primary in the radial direction and secondary in the circumferential direction.
[0028]
If the optical disk resonates at such a natural frequency, the optical disk largely fluctuates, so that the servo of the objective lens actuator 19 is not stabilized, and the optical disk 12 can accurately follow the laser beam from the objective lens 17. And the recording / reproducing of the optical disc 12 is adversely affected.
[0029]
The arithmetic unit 22 stores the natural frequencies fA1 and fA2 of the optical disk A and the natural frequencies fB1 and fB of the optical disk B in a memory built in the arithmetic unit 22 in advance. Is determined, the natural frequency of the determined type of optical disk is read from the memory. Then, assuming that the product of the number of blades and the number of revolutions of the fan 24 is the fundamental frequency, the arithmetic unit 22 sets the number of revolutions of the fan 24 so that an integer multiple thereof does not match the natural frequency of the optical disk.
[0030]
Here, it is assumed that the air pressure changes due to the wind-off of the fan 24, and the inside of the apparatus is vibrated by the fan 24 due to the air pressure change. At this time, the vibration generated by the fan 24 has a frequency component whose value is an integral multiple of the fundamental frequency. Therefore, the rotation speed of the fan 24 is set by the arithmetic unit 22 so that the frequency of the vibration generated by the fan 24 does not match the natural frequency of the optical disk.
[0031]
When the rotation speed of the fan 24 is set, the arithmetic unit 22 generates a drive signal for rotating the fan 24 at the set rotation speed, and applies the drive signal to the fan 24 through the amplification circuit 23. Thus, the fan 24 rotates at the set rotation speed.
[0032]
If the frequency of the vibration generated by the fan 24 is set so as not to coincide with the natural frequency of the optical disk, the optical disk 12 will not resonate. As a result, the servo of the objective lens actuator 19 is stabilized, the tracking of the optical disk 12 by the laser beam from the objective lens 17 is maintained well, and the recording and reproduction of the optical disk 12 are always performed well.
[0033]
For example, if the optical disk on the turntable is determined to be the optical disk A by the optical disk size detection unit 21, the arithmetic unit 22 reads out the respective natural frequencies fA1 and fA2 of the optical disk A from the built-in memory, and The rotation speed of the fan 24 is set so that the value of the integral multiple of the frequency does not coincide with each of the natural frequencies fA1 and fA2 of the optical disk A, that is, the frequency of the fan 24 does not coincide with the natural frequency of the optical disk A. The fan 24 is driven to rotate at the rotation speed through the circuit 23.
[0034]
Similarly, when the optical disk on the turntable is determined to be the optical disk B by the optical disk size detection unit 21, the arithmetic unit 22 reads out the respective natural frequencies fB 1 and fB 2 of the optical disk B from the built-in memory and operates the fan 24. The number of revolutions of the fan 24 is set so that a value of an integral multiple of the fundamental frequency does not match each of the natural frequencies fB1 and fB2 of the optical disc B, that is, the frequency of the fan 24 does not match the natural frequency of the optical disc B. The fan 24 is driven to rotate at the rotation speed through the amplifier circuit 23.
[0035]
As described above, in the present embodiment, the type of the optical disk is determined, the natural frequency of the optical disk of this type is read from the memory, and the fan 24 is driven to rotate so that the frequency of the fan 24 does not match the natural frequency of the optical disk. are doing. Therefore, the optical disk 12 does not resonate, the servo of the objective lens actuator 19 is stabilized, the tracking of the optical disk 12 by the laser beam from the objective lens 17 is maintained well, and the recording and reproduction of the optical disk 12 is always performed well. Is
[0036]
The frequency of the vibration generated by the fan 24 is controlled to be different from the natural frequency of the optical disk, and at the same time, the rotation speed of the fan 24 is set in accordance with the temperature change in the optical disk device to suppress the temperature rise in the optical disk device. May be controlled. In this case, the temperature in the optical disk device is detected, the rotational speed of the fan 24 corresponding to the detected temperature is temporarily set, and the frequency of the fan 24 at the temporarily set rotational speed is the natural frequency of the optical disk. Is determined, and if they do not match, the provisionally set rotation speed is determined as the rotation speed of the fan 24. If they match, the frequency of the vibration generated by the fan 24 is determined from the natural frequency of the optical disk. The provisionally set rotation speed is appropriately increased so as to deviate, and the increased rotation speed is determined as the rotation speed of the fan 24.
[0037]
Further, the type of the optical disk may be determined not only based on the dimensions of the optical disk but also based on the manufacturer and model number of the optical disk. In this case, data such as the manufacturer and model number is read from the optical disk, and the determination is made based on the data. Alternatively, the shape and size of the cartridge storing the optical disk may be detected, and the type of the optical disk may be determined based on the shape and size of the cartridge. The data read from the optical disk may be information on the natural frequency of the optical disk instead of the model number.
[0038]
Further, the vibration mode of the optical disk is not particularly limited, and an appropriate vibration mode may be selected according to the natural frequency characteristics of the optical disk or the servo characteristics of the objective lens actuator.
[0039]
Further, not only the frequency of the vibration generated by the fan may be deviated from the natural frequency of the optical disk, but also the vibration of the fan and the vibration due to other factors of the optical disk may be made to interact such that they cancel each other.
[0040]
【The invention's effect】
As described above, according to the present invention, the rotation speed of the fan is controlled such that the frequency of the vibration generated by the fan deviates from the natural frequency of the optical disk. Therefore, the frequency of the fan does not coincide with the natural frequency of the optical disk, and the optical disk does not resonate. As a result, the servo of the objective lens actuator is stabilized, the tracking of the optical disk by the laser light from the objective lens is maintained well, and the recording and reproduction of the optical disk are always performed well.
[0041]
Further, since the natural frequency of the optical disk differs depending on the type of the optical disk, the type of the optical disk is detected, and the rotation frequency of the fan is controlled so that the frequency of the fan deviates from the natural frequency of the detected type of optical disk. are doing. Accordingly, it is possible to prevent resonance of the optical disk even when any of various optical disks is driven to rotate.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of an optical disk device of the present invention.
FIG. 2 is a graph showing a natural frequency characteristic of each optical disc used in the apparatus of FIG.
FIG. 3 is a diagram schematically showing a conventional optical disk device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Optical disk rotation part 12 Optical disk 13 Rotation control part 14 Semiconductor laser 15 Collimating lens 16 Mirror 17 Objective lens 18 Lens holder 19 Objective lens actuator 21 Optical disk size detection part 22 Operation device 23 Amplification circuit 24 Fan

Claims (2)

An optical disc device having an optical pickup device that irradiates a laser beam onto the optical disc through an objective lens while rotating the optical disc and detects the laser light reflected from the optical disc,
A fan for ventilating the inside of the optical disc device;
An optical disc device, comprising: control means for controlling the number of revolutions of the fan such that an integral multiple of the fundamental frequency corresponding to the number of revolutions of the fan deviates from the natural frequency of the optical disc. A detecting unit for detecting a type of the optical disc;
2. The optical disk according to claim 1, wherein the control unit controls the number of revolutions of the fan so that a value of an integral multiple of the fundamental frequency deviates from the natural frequency of the type of optical disk detected by the detection unit. apparatus.

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