JPH03147532A - Optical disk device - Google Patents

Abstract

PURPOSE:To protect an actuator from being burned by measuring the temperature of an actuator itself by using the terminal voltage and the driving current of an actuator coil, and stopping at least the operation of an optical head when the temperature exceeds allowable temperature. CONSTITUTION:The terminal voltage of the actuator coil 4 is measured, and the internal resistance of the actuator coil is calculated from the voltage value of the coil and the driving current of the actuator coil 4. Then, the temperature of the actuator coil is calculated with the resistance value by using the temperature characteristic of the internal resistance of the actuator coil 4. When the temperature of the actuator coil 4 exceeds a prescribed value, at least the operation of the optical head is stopped. Thereby, it is possible to prevent the actuator coil burned when the temperature of the actuator coil 4 exceeds the allowable temperature due to the application of oscillation over specification, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an optical disc device having an actuator that performs trunking servo control, focus servo control, and the like.

B1 Summary of the Invention The present invention provides an actuator coil of an optical head, a current supply means for supplying a drive current to the actuator coil, a voltage measurement means for measuring a terminal voltage of the actuator coil, and a voltage value from the voltage measurement means and an actuator. A resistance value calculation means that calculates the internal resistance of the actuator coil from the drive current value of the coil, and a temperature that calculates the temperature of the actuator coil using the temperature characteristic of the internal resistance of the actuator coil based on the resistance value from the resistance value calculation means. The apparatus includes a calculation means and a control means for at least stopping the operation of the optical head when the temperature of the actuator coil from the temperature calculation means exceeds a predetermined value, thereby preventing burnout of the actuator due to excessive vibration, etc. It is something.

C0 Conventional technology In an optical disk device, information (data) is recorded and reproduced by focusing laser light from a laser light source with an objective lens and irradiating it onto the recording surface of the disk. This is done by detecting the strength of the reflected light.

In other words, in order to record and reproduce data, it is necessary to accurately move the laser beam spot to the target track and selector on the disk, and to keep the focus of the objective lens of the optical head always on the recording surface of the disk. be. The driving elements that move and hold the laser beam include a focusing actuator that keeps the focus of the objective lens on the recording surface of the disk, a tracking actuator that keeps the laser beam spot at the center of the track, and a tracking actuator that cooperates with the tracking actuator. A coarse movement actuator that moves a laser beam to a target track by moving the laser beam to a target track is known.

As these actuators, for example, moving coil motors (voice coil motors), which have a structure similar to that of Guinami speakers consisting of a moving coil, a permanent magnet, and a magnetic body (yoke), are mainly used, and as coarse movement actuators, For example, a linear motor is used.

The coils used in these actuators, for example the coils used in tracking actuators, can be used in multi-track jump or single-track jump when used in an environment with relatively little vibration, such as when an optical disk device is used as storage for a desktop computer. It is designed taking into account the power required to perform the tracking operation, and also has a current limit to protect the actuator from driver failure, and protects the driver from ground faults in the actuator. Protection measures such as current limits are taken to prevent this.

D1 Problem to be solved by the invention' By the way, when used in an environment with a lot of vibration, such as inside a car or an airplane, electric power is also required to withstand (overcome) this vibration, and the above-mentioned tracking etc. The actuator coil must be designed by adding this power to the power required for operation. Furthermore, it is necessary to at least protect the actuator from burnout, assuming that vibrations exceeding the vibration resistance specifications will be applied.

The present invention has been made in view of the above circumstances, and provides an optical disc device that can prevent actuator burnout when the temperature of the actuator coil rises above the allowable temperature due to vibrations exceeding specifications, etc. For the purpose of providing.

81 Means for Solving the Problems The optical disc device according to the present invention includes an actuator coil of an optical head, a current supply means for supplying a drive current to the actuator coil, and a voltage measurement means for measuring a terminal voltage of the actuator coil. , resistance value calculation means for calculating the internal resistance of the actuator coil from the voltage value from the voltage measurement means and the driving current value of the actuator coil, and the resistance value from the resistance value calculation means,
temperature calculation means for calculating the temperature of the actuator coil using the temperature characteristics of the internal resistance of the actuator coil; and at least stopping the operation of the optical head when the temperature of the actuator coil from the temperature calculation means is equal to or higher than a predetermined value. The above problem is solved by having a control means.

F0 Effect In the optical disc device according to the present invention, when the temperature of the actuator coil exceeds a predetermined value, at least the operation of the optical head is stopped.

G. Embodiment Hereinafter, an embodiment of the optical disc device according to the present invention will be described with reference to the drawings. FIG. 1 is a block circuit diagram of essential parts of an optical disc device according to the present invention.

This optical disk device is, for example, a write-once optical disk device, a write-once optical disk device, a rewritable magneto-optical disk device, etc., and a disk-shaped recording medium (disk) is driven to rotate at a constant angular velocity or linear velocity by a spindle motor. However, data (information) is recorded and reproduced on recording tracks provided spirally or concentrically on the disk. When recording and reproducing data, the spot of the laser beam is guided to the target trunk or selector, and the laser beam is irradiated with the objective lens always focused on the recording surface of the disk. In this case, the strength of the reflected light from the disc is detected and the data is reproduced.

Drive elements that move and hold the laser beam spot in this way include, for example, a focusing actuator that keeps the focus of the objective lens of the optical head always on the recording surface of the disk, and a focusing actuator that keeps the laser beam spot at the center of the track. A tracking actuator and a coarse movement actuator are used to move a laser beam to a target track in cooperation with the tracking actuator. As these actuators, for example, moving coil type motors (voice coil motors), which have a structure similar to the Guinami Kususpi force consisting of a moving coil, a permanent magnet, and a magnetic body (yoke), are used, and as coarse movement actuators,
For example, a linear motor is used. In this embodiment, in order to protect these actuators from burnout, the temperature of the actuator coil is calculated from the temperature characteristics of the terminal voltage of the actuator coil, the drive current, and the resistance of the actuator coil, and when the temperature exceeds a predetermined temperature, , the operation of the entire optical disk device is stopped. Here, a tracking actuator will be explained as a specific example.

That is, the optical disc device of this embodiment, as shown in FIG. 1, includes an actuator coil 4 to which a drive current is supplied by a drive circuit 3. As shown in FIG. This actuator coil 4 is, for example, a tracking actuator coil that constitutes a so-called two-axis device that moves an objective lens of an optical head in a focusing direction and a tracking direction.

The drive circuit 3 selectively inputs a drive voltage applied to a terminal 1 for controlling normal tracking, multi-track jump, etc. and a test voltage generated by a test voltage generator 6 via a changeover switch 2. It is now possible to do so. The drive circuit 3 converts the input voltage into a current and supplies the actuator coil 4 with a drive current corresponding to the input voltage.

Further, the changeover switch 2 performs a switching operation between the drive voltage and the test voltage in response to a changeover control signal from the controller 5.

Furthermore, the drive circuit 3 and the actuator coil 4
An A/D converter 7 is connected to the connection point. This A/D converter 7 digitizes the terminal voltage of the actuator coil 4 driven by the drive circuit 3. Digital data of the terminal voltage obtained by this A/D converter 7 is given to the controller 5.

In FIG. 1, when normal tracking, multi-track jump, etc. are performed, a drive voltage for controlling normal tracking, multi-track jump, etc. is supplied to terminal 1.

This drive voltage is selected by the changeover switch 2, and the voltage /
The signal is sent to a drive circuit 3 that performs current conversion. This drive circuit 3
The driving voltage is converted into a driving current and supplied to the actuator coil 4, and the objective lens of the so-called two-axis device of the optical head is driven in the radial direction of the optical disk, thereby performing tracking servo control.

When normal access operations such as tracking and multi-track jumps are not performed, the changeover control signal from the controller 5 switches the changeover switch 2, and a test voltage of a predetermined voltage value is applied to the drive circuit 3 from the test voltage generator 6. A drive current corresponding to the test voltage is supplied to the actuator coil 4. This terminal voltage of the actuator coil 4 is converted into digital data by the A/D converter 7, and this data is sent to the controller 5. By the way, as shown in FIG. 2, when the changeover switch 2 is changed over by a changeover control signal from the controller 5, an electromotive force is generated due to the self-inductance of the actuator coil 4. Therefore, after this transient phenomenon has sufficiently subsided and the terminal voltage of the actuator coil 4 becomes stable, it is sampled and converted into digital data, and this data is sent to the controller 5.

In the controller 5, the resistance of the actuator coil 4 is calculated from the terminal voltage and drive current of the actuator coil 4, that is, the digital data and the test voltage. Then, the temperature of the actuator coil 4 is calculated using the known temperature characteristics of the resistance of the actuator coil 4. When the calculated temperature exceeds a predetermined temperature (permissible temperature), a control signal for stopping the operation of the optical disk device is output from the controller 5 from the terminal 8, so that the operation of the entire optical disk device is stopped.

In this way, the temperature of the actuator coil 4 itself is measured using the terminal voltage and drive current of the actuator coil 4, and when the temperature exceeds the allowable temperature, the operation of the entire optical disk device is stopped, thereby protecting the actuator coil 4 from burning out. can do. Further, it is possible to suppress the temperature rise of the optical disc device, and reliability can be improved.

Note that the present invention is not limited to the above-mentioned embodiments, but can also be applied to focusing actuators and the like. Furthermore, instead of stopping the operation of the entire optical disc device as described above, it is sufficient to stop the operation of at least the optical head.

H0 Effects of the Invention As is clear from the above explanation, in the present invention, the temperature of the actuator coil itself is measured using the terminal voltage and drive current of the actuator coil, and when the temperature exceeds the allowable temperature, at least the operation of the optical head is controlled. By stopping, the actuator can be protected from burnout.

Further, it is possible to suppress the temperature rise of the optical disc device, and improve reliability.

A/D converter

Claims (1)

[Scope of Claims] An actuator coil of an optical head, a current supply means for supplying a drive current to the actuator coil, a voltage measuring means for measuring a terminal voltage of the actuator coil, and a voltage value from the voltage measuring means. A resistance value calculation means for calculating the internal resistance of the actuator coil from the drive current value of the actuator coil, and a temperature characteristic of the actuator coil using the resistance value from the resistance value calculation means and the temperature characteristic of the internal resistance of the actuator coil. An optical disc device comprising: temperature calculation means for calculating the temperature of the actuator coil; and control means for stopping at least the operation of the optical head when the temperature of the actuator coil from the temperature calculation means is equal to or higher than a predetermined value.