JP3727856B2 - Optical disk device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disc apparatus that records and reproduces information with respect to an optical disc, and more particularly, to a driving method of a spindle motor that rotationally drives an optical disc.
[0002]
[Prior art]
The spindle motor of the optical disk apparatus is constituted by, for example, a three-phase brushless motor, and rotates a CD or DVD optical disk at a variable rotation speed of generally 1000 rpm to 10000 rpm. In each phase constituting the fixed winding of the spindle motor, the ratio of the current flowing time, that is, the energization time and the non-energization time is represented by the energization angle. The energization angle of the spindle motor driver is constant regardless of the rotation speed.
[0003]
In general, the conduction angle is large for a driver that emphasizes high-speed rotation, and is small for a driver that emphasizes low-speed rotation or low current consumption. In general, when the energization angle is large, noise and vibration are small, and when the energization angle is small, noise and vibration are large.
[0004]
[Problems to be solved by the invention]
Conventionally, the current-carrying angle is constant regardless of the rotational speed, so drivers that emphasize high-speed rotation are disadvantageous in terms of current consumption at low-speed rotation, while focusing on low-speed rotation or low current consumption. Drivers are disadvantageous in terms of high-speed rotation, noise, and vibration.
[0005]
Accordingly, an object of the present invention is to provide an optical disc apparatus that drives a spindle motor with a minimum necessary current consumption with low noise and vibration from low speed rotation to high speed rotation.
[0006]
[Means for Solving the Problems]
By varying the energization angle of the spindle motor driver in accordance with the motor rotation speed, current consumption can be further suppressed during low-speed rotation, and noise and vibration can be further suppressed during high-speed rotation.
[0007]
In other words, the optical disk apparatus of the present invention has a spindle motor that rotates the optical disk, an objective lens, a first drive coil that moves the objective lens in the focusing direction, and a second drive coil that moves in the tracking direction. An optical pickup that irradiates the optical disk with a laser beam spot through the objective lens and provides a light detection signal based on reflected light from the disk, and controls the rotation of the spindle motor to a specified number of rotations. A rotation control means for driving the spindle motor based on a rotation control signal provided from the rotation control means, and a drive means for driving the spindle motor at a specified energization angle, and in response to a disk read instruction from the host device. sets a predetermined number of revolutions to the rotation controller, versus the rotational speed increase of the spindle motor With reference to the reference table for storing the conduction angle increases, and obtains the conduction angle according to the predetermined rotational speed, a drive control means for setting a vent electrostatic angle to said drive means, are provided from the optical pickup A focusing control means for providing a focus control signal to the first drive coil based on the light detection signal, and a tracking control signal for the second drive coil based on the light detection signal provided from the optical pickup. Tracking control means to be provided, and reproduction means for reproducing information recorded on the optical disc from the light detection signal in a state where the laser beam is controlled by the focusing control means and the tracking control means.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0010]
FIG. 1 is a block diagram showing the configuration of an optical disc apparatus to which the present invention is applied. This optical disc apparatus records, reproduces, and erases information with respect to the optical disc 1 using convergent light.
[0011]
A track is spirally formed on the surface of the disk 1, and the disk 1 is rotationally driven by a spindle motor 3. The spindle motor driver 35 drives the spindle motor 3 according to the rotation control signal transferred from the motor control circuit 4 and the energization angle control signal CAC according to the present invention transferred from the CPU 30.
[0012]
Information recording and reproduction with respect to the optical disc 1 are performed by the optical pickup 5. The optical pickup 5 is connected to a thread motor 6 through a gear, and the thread motor 6 is controlled by a thread motor control circuit 8.
[0013]
A speed detection circuit 9 is connected to the thread motor control circuit 8, and a speed signal of the optical pickup 5 detected by the speed detection circuit 9 is sent to the thread motor control circuit 8. A permanent magnet (not shown) is provided in the fixed portion of the thread motor 6, and the optical pickup 5 moves in the radial direction of the optical disk 1 when the drive coil 7 is excited by the thread motor control circuit 8.
[0014]
The optical pickup 5 is provided with an objective lens 10 supported by a wire or a leaf spring (not shown). The objective lens 10 can be moved in the focusing direction (the optical axis direction of the lens) by driving the drive coil 12, and can be moved in the tracking direction (the direction orthogonal to the optical axis of the lens) by driving the drive coil 11. Is possible.
[0015]
A laser beam is emitted from the semiconductor laser oscillator 19 by the laser drive circuit 15 of the laser control circuit 13. A light beam emitted from the semiconductor laser oscillator 19 is irradiated onto the optical disc 1 through the collimator lens 20, the half prism 21, and the objective lens 10. The reflected light from the optical disk 1 is guided to the photodetector 24 through the objective lens 10, the half prism 21, the condenser lens 22, and the cylindrical lens 23.
[0016]
The light detector 24 is composed of four divided light detection cells 24a to 24d. Output signals of the photodetection cells 24a to 24d are supplied to the differential amplifiers OP1 and OP2 via the current / voltage conversion amplifiers 25a to 25d and the adders 26a to 26d.
[0017]
The differential amplifier OP2 outputs a signal related to the focus point according to the difference between both output signals of the adders 26a and 26b. This output is supplied to the focusing control circuit 27. The output signal of the focusing control circuit 27 is supplied to the focusing drive coil 12. As a result, the laser beam is controlled to be always just focused on the optical disc 1.
[0018]
The differential amplifier OP1 outputs a track difference signal corresponding to the difference between both output signals of the adders 26c and 26d. This output is supplied to the tracking control circuit 28. The tracking control circuit 28 generates a track drive signal according to the track difference signal from the differential amplifier OP1.
[0019]
The track drive signal output from the tracking control circuit 28 is supplied to the drive coil 11 in the tracking direction. The track difference signal used in the tracking control circuit 28 is supplied to the sled motor control circuit 8.
[0020]
By performing the focusing control and the tracking control, an adder 26e for adding the output signals of the adders 26c and 26d to the sum signal of the output signals of the photodetection cells 24a to 24d of the photodetector 24 is added. The output signal reflects a change in reflectance from a bit or the like formed on the track of the optical disc 1 corresponding to the recording information. This signal is supplied to the data reproduction circuit 18. The data reproduction circuit 18 reproduces the recorded data based on the reproduction clock signal from the PLL circuit 16.
[0021]
When the objective lens 10 is controlled by the tracking control circuit 28, the sled motor control circuit 8 controls the sled motor 6, that is, the optical pickup 5 so that the objective lens 10 is positioned near the center position in the optical pickup 5. .
[0022]
The motor control circuit 4, thread motor control circuit 8, laser control circuit 13, PLL circuit 16, data reproduction circuit 18, focusing control circuit 27, tracking control circuit 28, error correction circuit 2, etc. are controlled by the CPU 30 via the bus 29. Is done. The CPU 30 uses the RAM 31 as a work area and performs a predetermined operation according to a program including the present invention recorded in the ROM 32.
[0023]
Next, a method for controlling the energization angle of the spindle motor driver according to one embodiment of the present invention will be described.
[0024]
In the present embodiment, a three-phase brushless motor is used as the spindle motor 3. FIG. 2 shows the configuration of the fixed winding 40 of the three-phase brushless motor and the driver unit 41 of the spindle motor driver 35. The fixed winding 40 is composed of a U phase, a V phase, and a W phase, and the motor driver unit 41 is composed of upper transistors Tr1, Tr3, Tr5 and lower transistors Tr2, Tr4, Tr6. The collectors of the transistors Tr1, Tr3, Tr5 are connected to a positive power source, and the emitters of the transistors Tr2, Tr4, Tr6 are connected to a negative power source.
[0025]
The U phase is connected to the emitter of the transistor Tr1 and the collector of the transistor Tr2. The V phase is connected to the emitter of the transistor Tr3 and the collector of the transistor Tr4. The W phase is connected to the emitter of the transistor Tr5 and the collector of the transistor Tr6.
[0026]
FIG. 3 is a diagram showing a U-phase drive voltage waveform in FIG. A positive voltage is applied to the U phase when the transistor Tr1 is ON and at least one of the transistors Tr4 or Tr6 is ON. A negative voltage is applied to the U phase when the transistor Tr2 is ON and at least one of the transistors Tr3 or Tr5 is ON. A voltage is applied. When both of the transistors Tr1 and Tr2 are OFF, the U phase has a high impedance. The voltage waveforms of the V phase and the W phase are the same, and the phases are 120 degrees and 240 degrees different from the U phase. The energization angle (electrical angle) is expressed as 180a / (a + b) degrees using a period in which voltage is applied to each phase and current flows, that is, energization period a, and a period in which no current flows, that is, non-energization period b. The The energization angle of the conventional spindle motor driver is constant regardless of the rotation speed.
[0027]
FIG. 4 shows an example of U-phase, V-phase, and W-phase drive waveforms. In this example, the conduction angle is 120 degrees, and the drive waveforms have a phase difference of 120 degrees. As illustrated, for example, during phase P1, the current flows from the U phase to the V phase, and during phase P2, the current flows from the U phase to the W phase. Thus, by driving the fixed winding of the spindle motor, a rotating magnetic field is generated, torque is generated by a magnet of a rotor (not shown), and the spindle motor rotates.
[0028]
In the present invention, the energization angle (180a / (a + b)) of the spindle motor driver is controlled by controlling a / (a + b) according to the rotational speed (a + b) of the spindle motor. For example, when 1000 rpm is instructed as the motor rotation speed, the energization angle is set to 120 degrees, the energization angle increases as the instructed rotation speed increases, and when the rotation speed of 10,000 rpm is instructed, the energization angle is For example, it is set to 180 degrees.
[0029]
FIG. 5 shows drive waveforms of the U phase, the V phase, and the W phase when the energization angle is set to 180 degrees. When 180 degrees is set as the energization angle in this way, a current always flows through the fixed winding of each phase. Also in this case, the phase difference between the drive waveforms is 120 degrees. For example, in the case of the U phase, the positive drive voltage is applied during the phases P1 ′ to P3 ′ with the rotation angle of 0 ° to 180 °, and the negative polarity is applied during the phases P4 ′ to P6 ′ with the rotation angle of 180 ° to 360 °. A drive voltage is applied and current flows.
[0030]
As described above, in the present invention, the energization angle is set to an appropriate value between 120 degrees and 180 degrees in accordance with the rotational speed of the motor instructed by the CPU 30.
[0031]
FIG. 6 is a flowchart showing the energization angle control method of the spindle motor driver according to the present invention. 1 receives a read or write command from the host device 34 via the interface circuit 33 (step S1), the CPU 30 sets a target rotational speed of the motor (step S2). Next, the optimum energization angle corresponding to the motor rotation speed is read from the reference table 42 (step S3).
[0032]
In the conduction angle reference table 42, as shown in FIG. 7, appropriate conduction angles of 120 degrees to 180 degrees are stored corresponding to the motor rotation speeds of 1000 rpm to 10,000 rpm.
[0033]
When the energization angle is determined with reference to the energization angle reference table 42 (step S3), the CPU 30 transmits the energization angle to the spindle motor driver 35 as an energization angle control signal CAC (step S4).
[0034]
The spindle motor driver 35 drives the spindle motor 3 based on the energization angle control signal CAC transmitted from the CPU 30 and the motor rotation control signal transmitted from the motor control circuit 4.
[0035]
【The invention's effect】
By configuring the system according to the present invention as described above, it is possible to realize an optical disc apparatus that can further suppress current consumption during low-speed rotation and can further suppress noise and vibration during high-speed rotation.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an optical disc apparatus to which the present invention is applied.
FIG. 2 is a circuit diagram showing a configuration of a fixed winding of a three-phase brushless motor and a driver portion thereof.
FIG. 3 is a diagram showing U-phase drive voltage waveforms in FIG. 2;
FIG. 4 is a diagram illustrating drive waveforms of a U phase, a V phase, and a W phase when the conduction angle is 120 degrees.
FIG. 5 is a diagram showing drive waveforms of a U phase, a V phase, and a W phase when the energization angle is 180 degrees.
FIG. 6 is a flowchart showing a method of controlling the energization angle of the spindle motor driver according to the present invention.
FIG. 7 is a view showing a reference table storing energization angles suitable for various rotation speeds of a spindle motor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical disk, 3 ... Spindle motor, 10 ... Objective lens, 11, 12 ... Lens drive coil, 20 ... Collimator lens, 21 ... Half prism, 22 ... Condensing lens, 23 ... Cylindrical lens, 24a-24d ... Photodetection cell 25a to 25d ... current / voltage conversion amplifiers, 26a to 26d ... adders, 35 ... spindle motor drivers.

Claims (2)

A spindle motor that rotates the optical disk;
An objective lens, a first drive coil that moves the objective lens in the focusing direction, and a second drive coil that moves in the tracking direction, and irradiates the rotating optical disc with a laser beam spot through the objective lens And an optical pickup that provides a light detection signal based on the reflected light from the disk;
Rotation control means for controlling the rotation of the spindle motor to a specified number of rotations;
Drive means for driving the spindle motor at a designated energization angle based on a rotation control signal provided from the rotation control means;
Depending on the disk read instruction from the host device sets the predetermined rotational speed to said rotation control means, by referring to the reference table for storing the conduction angle increases in response to the rotation speed increase of the spindle motor, the A drive control means for obtaining an energization angle corresponding to a predetermined rotational speed and setting the energization angle in the drive means;
Focusing control means for providing a focus control signal to the first drive coil based on the light detection signal provided from the optical pickup;
Tracking control means for providing a tracking control signal to the second drive coil based on the light detection signal provided from the optical pickup;
Reproducing means for reproducing information recorded on the optical disc from the light detection signal in a state where the laser beam is controlled by the focusing control means and the tracking control means;
An optical disc apparatus comprising:   2. The optical disk apparatus according to claim 1, wherein the reference table stores energization angles of 120 to 180 degrees corresponding to the spindle motor rotation speeds of 1000 to 10,000 rpm.

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