JP3796108B2 - Disk unit - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a disk device, and more particularly to, for example, a disk device that moves an optical pickup in a radial direction of a disk recording medium for a seek operation.
[0002]
[Prior art]
In the disk device, it is necessary to rotate the thread motor in order to move the optical pickup in the radial direction of the disk recording medium for the seek operation. For this reason, in the prior art, a thread control voltage is output at the time of seek, and the thread motor is rotated in a predetermined direction.
[0003]
[Problems to be solved by the invention]
However, in the prior art, since the thread control voltage is always set to a predetermined value, there is a possibility that the thread motor cannot be rotated properly when the load changes. For example, when the temperature is low, the adhesiveness of the lubricating oil increases and an excessive load is applied to the sled motor. At this time, if the sled motor is driven with the same voltage as that at room temperature, the rotation speed of the sled motor may be reduced, or in the worst case, the rotation may stop. Here, if the sled control voltage is always set to a high value, the sled motor rotates even when it is overloaded, but noise during a seek operation increases.
[0004]
Therefore, a main object of the present invention is to provide a disk device capable of performing a stable seek operation regardless of a change in load amount.
[0005]
[Means for Solving the Problems]
The present invention relates to a disk apparatus, a mounting means for mounting a disk recording medium having a track formed on a recording surface, an optical pickup for irradiating the recording surface with laser light, and moving the optical pickup in a radial direction of the recording surface A first detecting means for detecting a tracking error signal based on the laser beam reflected from the recording surface, a raising means for raising a control voltage of the motor when a period of the tracking error signal is longer than a threshold value, And setting means for setting the control voltage of the motor to a predetermined value when the period of the tracking error signal is equal to or shorter than a threshold value, and the control voltage of the motor is raised by the raising means, or The setting of the motor control voltage by the setting means is performed by moving the optical pickup for seek operation. And characterized in that it is carried out in.
[0007]
In the present invention, when a disk recording medium having a track formed on the recording surface is mounted by the mounting means and the optical pickup irradiates the recording surface with laser light, a tracking error signal is generated based on the laser light reflected from the recording surface. Is detected by the first detection means. When the optical pickup is moved in the radial direction of the recording surface by the motor, if the period of the tracking error signal is longer than the threshold value, the control voltage of the motor is raised by the raising means. On the other hand, if the period of the tracking error signal is equal to or shorter than the threshold, the motor control voltage is set to a predetermined value by the setting means.
[0008]
Therefore, when the period of the tracking error signal is longer than the threshold value because the rotation speed of the motor is slow, the control voltage of the motor increases and the rotation speed is accelerated. When the rotation speed increases and the period of the tracking error signal becomes equal to or shorter than the threshold value, the motor control voltage is set to a predetermined value. By setting the predetermined value, the rotational speed of the motor decreases, and when the period of the tracking error signal becomes longer than the threshold value, the rotational speed of the motor is accelerated again.
[0009]
Preferably, the increasing means increases the control voltage by adding a voltage value related to an error between the period of the tracking error signal and the threshold value to a predetermined value.
[0010]
Further, the ambient temperature of the motor may be detected by the second detection means, and the predetermined value may be varied according to the detected ambient temperature.
[0012]
【The invention's effect】
According to the present invention, when the rotation speed of the motor is slow, the control voltage of the motor is increased to increase the rotation speed, and when the rotation speed increases, the period of the tracking error signal becomes equal to or shorter than the threshold value. Since the motor control voltage is set to a predetermined value, a stable seek operation can be performed regardless of changes in the load amount.
[0014]
The above object, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.
[0015]
【Example】
Referring to FIG. 1, an optical disc apparatus 10 of this embodiment includes an optical pickup 12 provided with an optical lens 14. The optical lens 14 is supported by the tracking actuator 16 and the focus actuator 18, and the laser light emitted from the laser diode 20 is converged by such an optical lens 14 and magneto-optical such as an ASMO (Advanced Storage Magneto Optical disc). The recording surface of the disk 44 is irradiated. As a result, a desired signal is recorded on the magneto-optical disk 44 or reproduced from the magneto-optical disk 44.
[0016]
The magneto-optical disk 44 is mounted on a spindle 46 and is rotated by a spindle motor 48. The magneto-optical disk 44 is a ZCLV (Zone Constant Linear Velocity) disk, and the rotational speed decreases as the optical pickup 12 moves from the inner periphery to the outer periphery.
[0017]
Reflected light from the recording surface passes through the same optical lens and is irradiated to the photodetector 22. The output of the photodetector 22 is input to an FE signal detection circuit 24 and a TE signal detection circuit 26, and an FE (Focus Error) signal and a TE (Tracking Error) signal are detected respectively. The detected FE signal and TE signal are given to a DSP (Digital Signal Processor) 36 via A / D converters 34a and 34b, respectively.
[0018]
The DSP 36 executes focus servo processing based on the FE signal, and executes tracking servo processing and thread servo processing based on the TE signal. A focus actuator control voltage is generated by the focus servo process, and the focus actuator control voltage is output to the focus actuator 18 via the D / A converter 44b. A tracking actuator control voltage is generated by the tracking servo process, and the tracking actuator control voltage is output from the D / A converter 44a to the tracking actuator 16. The position of the optical lens 14 in the optical axis direction is controlled by a focus actuator control voltage, and the radial position of the optical lens 14 is controlled by a tracking actuator control voltage. The DSP 36 further generates a thread control voltage by thread servo processing, and the pulse width of the PWM signal output from the PWM signal generation circuit 40 changes according to the thread control voltage. The rotational speed and direction of the thread motor 42 are controlled by such a PWM signal.
[0019]
The TE signal is also compared with a predetermined threshold by the comparator 28, and a TZC (Tracking Zero Cross) signal is output from the comparator 28. When the optical pickup 12 moves in the radial direction of the magneto-optical disk 44 for seeking, the TE signal changes as shown in FIG. 2A, and the TZC signal changes as shown in FIG. That is, the TZC signal rises at a zero level while the TE signal changes from a minus level to a plus level, and falls at a zero level while the TE signal changes from a plus level to a minus level. Such a TZC signal output from the comparator 28 is supplied to the ZC counter 30 and the period measurement circuit 32. The ZC counter 30 counts the rising edge of the TZC signal, and the period measuring circuit 32 measures the period of the TZC signal. The count value of the ZC counter 30 and the measurement period by the period measurement circuit 32 are given to the DSP 36 as they are.
[0020]
During the seek operation, the DSP 36 drives the sled motor 42 to move the optical pickup 12 in the radial direction of the magneto-optical disk 44. The thread control voltage at this time is determined based on the output of the temperature sensor 50 installed around the optical pickup 12 and the measurement period by the period measurement circuit 32. The temperature detected by the temperature sensor 50 corresponds to the temperature of the sled motor 42. The DSP 36 sets the initial value of the thread control voltage to the standard seek voltage (room temperature seek voltage) if the detected temperature is higher than the predetermined threshold, and sets the initial value of the thread control voltage to the initial value of the thread control voltage if the detected temperature is lower than the predetermined threshold. Set to low-temperature seek voltage (> standard seek voltage). The DSP 36 also maintains the thread control voltage at the initial value if the cycle of the TZC signal during the seek operation is equal to or less than the predetermined threshold, but if the cycle is longer than the predetermined threshold, the set thread control voltage is set to be lower than the initial value. Make it high.
[0021]
At low temperatures, the adhesiveness of the lubricating oil increases and the load on the thread motor 42 increases, so that the thread motor 42 may not rotate at an appropriate speed with the thread control voltage at room temperature. On the other hand, when the sled control voltage at normal temperature is set high, noise during a seek operation increases. Therefore, in this embodiment, if the temperature detected by the temperature sensor 50 is equal to or lower than a predetermined threshold value, a low-temperature seek control voltage higher than the standard seek voltage is set as an initial value, and the rotation of the sled motor 42 during seek is further performed. When the speed is low, the seek control voltage is increased from the initial value. Accordingly, the sled motor 42 can be rotated at an appropriate speed even when seeking is performed at a low temperature. In addition, the standard seek control voltage can be set low, and noise during a seek operation at room temperature can be suppressed.
[0022]
The photodetector 22, the FE signal detection circuit 24, and the TE signal detection circuit 26 are configured as shown in FIG. The photodetector 22 includes four detection elements 22a to 22d, and outputs of the detection elements 22a to 22d are subjected to different calculations in the FE signal detection circuit 24 and the TE signal detection circuit 26. Specifically, Equation 1 is calculated in the FE signal detection circuit 24, and Equation 2 is calculated in the TE signal detection circuit 26.
[0023]
[Expression 1]
FE = (A + C)-(B + D)
[0024]
[Expression 2]
TE = (A + D)-(B + C)
Note that “A” to “D” in Equations 1 to 3 correspond to the outputs of the detection elements 22a to 22d, respectively. The detection elements 22a and 22d detect the light component in the left half of the laser beam in the trace direction, and the detection elements 22b and 22c detect the light component in the right half of the laser beam in the trace direction.
[0025]
The DSP 36 controls the seek operation according to the flowchart shown in FIG. The DSP 36 is actually formed by a logic circuit, but a flow diagram is used for convenience of explanation.
[0026]
First, the tracking servo is stopped in step S1, and the ambient temperature data of the sled motor 42 detected by the temperature sensor 50 is fetched in step S3. In step S5, the captured ambient temperature data is compared with a predetermined threshold value. If ambient temperature> threshold value, the standard seek voltage is set as an initial value in step S7. If ambient temperature ≦ threshold value, low temperature is determined in step S9. Set the seek voltage as the initial value. When the process of step S7 or S9 is completed, the ZC counter 30 is reset in step S11, and a thread control voltage having the initial value set in step S7 or S9 is output. The thread motor 42 rotates in response to the PWM signal based on the thread control voltage, and the ZC counter 30 is incremented in response to the rising edge of the TZC signal output from the comparator 28.
[0027]
In step S15, it is determined whether or not the count value of the ZC counter 30 has reached “target value−1”. If NO, the cycle of the TZC signal (ZC cycle) is detected in step S17. That is, the measurement cycle by the cycle measurement circuit 32 is captured. In step S19, the detected ZC cycle is compared with a predetermined threshold, and the thread control voltage is updated in step S21 or S23 depending on the comparison result. That is, if ZC cycle> predetermined threshold, the thread control voltage is corrected according to Equation 3, and if ZC cycle ≦ predetermined threshold, the thread control voltage is set to an initial value in step S23.
[0028]
[Equation 3]
Thread control voltage = initial value + (measurement cycle−predetermined threshold) * gain When the process of step S21 or S23 is completed, the updated thread control voltage is output in step S25, and the process returns to step S15.
[0029]
Accordingly, if the rotation speed of the sled motor 42 is slower than the predetermined speed, the sled control voltage increases. If the rotation speed of the sled motor 42 exceeds the predetermined speed due to the increase of the sled control voltage, the sled control voltage is set to the initial value (standard). Voltage for seek or low-temperature seek).
[0030]
When the count value reaches “target value−1” in the ZC counter 30, the process proceeds from step S15 to step S27, and the thread motor 42 is braked. Specifically, a thread control voltage having a reverse polarity is output. When the rotation of the thread motor 42 is stopped by this, tracking servo is executed in step S29, and the process returns.
[0031]
As can be seen from the above description, the ambient temperature of the sled motor 42 is detected by the temperature sensor 50. If the detected ambient temperature is higher than the threshold, the standard seek voltage is determined as the initial value of the control voltage of the sled motor 42. Is done. On the other hand, if the detected ambient temperature is equal to or lower than the threshold value, a low-temperature seek voltage higher than the standard seek voltage is determined as the initial value of the control voltage of the sled motor 42. Therefore, when the ambient temperature is low and the sled motor 42 is overloaded, the sled motor 42 is driven by the seek voltage.
[0032]
When the optical pickup 12 is moved in the radial direction of the magneto-optical disk 44 by the thread motor 42, if the period of the tracking error signal is longer than the threshold value, the control voltage of the thread motor 42 is increased. On the other hand, if the period of the tracking error signal is equal to or shorter than the threshold, the control voltage of the sled motor 42 is set to the initial value.
[0033]
Accordingly, when the period of the tracking error signal is longer than the threshold value because the rotation speed of the sled motor 42 is slow, the control voltage of the sled motor 42 increases and the rotation speed is accelerated. If the period of the tracking error signal becomes equal to or shorter than the threshold value due to the increase in the rotation speed, the control voltage of the sled motor 42 is returned to the initial value. When the rotation speed of the sled motor 42 is reduced by returning to the initial value and the period of the tracking error signal becomes longer than the threshold, the rotation speed of the sled motor 42 is accelerated again. By adjusting the control voltage of the sled motor 42 in this manner, a stable seek operation can be performed regardless of changes in the load amount.
[0034]
In this embodiment, each time the period of the TE signal is detected once, the thread control voltage is adjusted by comparing the period with the threshold. However, the period of the TE signal is detected and detected a plurality of times. The thread control voltage may be adjusted by comparing the average value of a plurality of periods with a threshold value.
[0035]
In this embodiment, a magneto-optical disk such as ASMO is used as a disk recording medium. However, it goes without saying that the present invention can also be applied to a disk device for recording / reproducing a CD-ROM or DVD.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of the present invention.
2A is a waveform diagram showing a tracking error signal, and FIG. 2B is a waveform diagram showing a TZC signal.
FIG. 3 is a circuit diagram showing a photodetector, a TE signal detection circuit, and an FE signal detection circuit.
FIG. 4 is a flowchart showing a part of processing of a DSP during a seek operation.
FIG. 5 is a flowchart showing another part of the processing of the DSP during the seek operation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Optical disk apparatus 12 ... Optical pick-up 26 ... TE signal detection circuit 30 ... ZC counter 32 ... Period measurement circuit 36 ... DSP
42 ... Thread motor 50 ... Temperature sensor

Claims (3)

Mounting means for mounting a disk recording medium having a track formed on the recording surface;
An optical pickup for irradiating the recording surface with laser light;
A motor for moving the optical pickup in the radial direction of the recording surface;
First detection means for detecting a tracking error signal based on the laser light reflected from the recording surface;
A rising means for increasing the control voltage of the motor when the period of the tracking error signal is longer than a threshold, and the control voltage of the motor is predetermined when the period of the tracking error signal is equal to or shorter than the threshold. With setting means to set the value,
The disk apparatus characterized in that the control voltage of the motor is raised by the raising means or the control voltage of the motor is set by the setting means while the optical pickup is moving for a seek operation.   The disk device according to claim 1, wherein the raising means adds a voltage value related to an error between the period and the threshold value to the predetermined value. A second detecting means for detecting the ambient temperature of the motor;
The disk device according to claim 1, wherein the predetermined value varies depending on the ambient temperature.

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