JP2781911B2 - Protection circuit for optical disk mastering device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection circuit for an optical disk mastering device, and more particularly, to rotating a master disk by a spindle motor and irradiating a light beam onto the master disk via an objective lens. The present invention relates to a protection circuit for an optical disc mastering device that prevents an objective lens from dropping onto a master disc when a power failure occurs in an optical disc mastering device that performs cutting.

[Prior Art] FIG. 2 is a schematic block diagram showing a main part of a conventional optical disc mastering apparatus.

First, an outline of a conventional optical disc mastering apparatus will be described with reference to FIG. The disk 2 is driven and rotated by the spindle motor 1. The spindle motor 1 is driven by a drive amplifier 3. An objective lens 4 is provided above the disk 2, and the objective lens 4 is positioned at a position balanced with its own weight by the restoring force of a spring 6. A drive coil 5 for moving the objective lens 4 up and down against this restoring force is wound around the objective lens 4. The drive coil 5 is driven by a drive amplifier 7. Then, a light beam is irradiated onto the disk 2 via the objective lens 4, and information is cut on the disk 2.

[Problems to be Solved by the Invention] In the above-described optical disc mastering apparatus, when power is cut off due to a power failure, power supplied to the driving amplifiers 3 and 7 is also cut off. 1 is no longer driven and stops rotating. On the other hand, the drive coil 5 of the objective lens 4 is not driven by the drive amplifier 7, and when the objective lens 4 is pulled up immediately before or immediately after the start of cutting, the force for pushing up the objective lens 4 against the balance disappears, The objective lens 4 falls by its own weight, falls below the balance position by inertia, and falls onto the disk 2. For this reason, there is a problem that the disk 2 is damaged.

SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide a protection circuit for an optical disk mastering device capable of preventing the objective lens from dropping sharply onto the disk and damaging the disk even when the power is cut off.

Means for Solving the Problems The present invention relates to a protection circuit of an optical disk mastering apparatus for performing cutting by rotating a master disk by a driving force of a motor and irradiating a light beam to the master disk via an objective lens. The objective lens is positioned at a position balanced with its own weight by the restoring force of the elastic member, and a drive coil for moving the objective lens up and down against the balance is wound around the objective lens, and the drive coil is wound around the objective lens. A coil driving means for driving, a motor driving means for driving the motor, a large-capacity capacitor charged by a DC power supply, and a drive coil cut off from the coil driving means when the power supply is cut off, and a large-capacity capacitor A first switch for supplying a discharge voltage to the drive coil and gradually lowering the objective lens as the discharge voltage decreases. Exchange means,
A second switching unit for disconnecting the motor from the motor driving unit when the power is cut off, supplying a regenerative voltage generated by the inertial rotation of the motor to the driving coil via the first switching unit, and weakening the driving force of the driving coil; And is provided.

[Operation] The protection circuit of the optical disc mastering device according to the present invention, when the power supply circuit is cut off, disconnects the coil driving means from the driving coil and disconnects the motor from the motor driving means to drive the discharge voltage of the large-capacity capacitor. The regenerative voltage generated by the inertia rotation of the motor is supplied to the drive coil while being supplied to the coil, and the objective lens is gradually lowered to prevent the objective lens from dropping abruptly onto the master disk.

FIG. 1 is a schematic block diagram of an embodiment of the present invention.

First, the configuration of one embodiment of the present invention will be described with reference to FIG. Relay contacts 8a, 8b are provided between the drive coil 5 wound around the objective lens 4 and the drive amplifier 7.
Are connected, and relay contacts 8c, 8d, 8e are also connected between the spindle motor 1 and the driving amplifier 3. These relay contacts 8a to 8e are closed to the contact a when the power of 100V AC is supplied to the relay coil 8, and when a power failure occurs, the power of 100V AC supplied to the relay coil 8 is cut off. , Is switched to the contact b side.

More specifically, the terminal a of the contact 8a is connected to the output of the driving amplifier 7, the contact b is connected to one end of the large-capacity capacitor 11 via the resistor 14, and the terminal c is connected to one end of the drive coil 5. Connected to. The terminal a of the contact 8b is connected to the output of the driving amplifier 7, the terminal c is connected to the other end of the driving coil 5, and the terminal b is grounded. A DC voltage is applied to one end of the capacitor 11 via a backflow prevention diode 12 and a resistor 13. This DC voltage is the same as the DC voltage supplied to the driving amplifiers 3 and 7.

On the other hand, each terminal a of the contacts 8c, 8d, 8e is connected to the output of the driving amplifier 3, the terminal b is connected to the rectifier circuit 9, and the terminal c is connected to the spindle motor 1. This rectifier circuit 9 rectifies a regenerative voltage generated by coasting rotation of the spindle motor 1 when the power is cut off and the relay contacts 8c to 8e are switched to the terminal b. The rectified output of the rectifier circuit 9 is a diode 10, a resistor 14, and a relay contact
It is provided to one end of the drive coil 5 via 8a.

Next, a specific operation of the embodiment of the present invention will be described. When power is supplied, 100 V AC is applied to the relay coil 8, and the relay contacts 8a to 8e are each switched to the terminal a. For this purpose, the output of the drive amplifier 7 is given to the drive coil 5 and the objective lens 4
Is pushed upward against the balance with the spring 6. The output of the driving amplifier 3 is supplied to the spindle motor 1, and the spindle motor 1 rotates and the disk 2 also rotates. At this time, a DC voltage is applied to the capacitor 11 via the backflow prevention diode 12 and the resistor 13, and the capacitor 11 is charged.

Next, when the power is cut off, the AC 100 V supplied to the relay coil 8 is cut off, and the relay contacts 8a to 8e are respectively switched to the terminals b. Then, the discharge voltage of the capacitor 11 is changed from the resistor 14 to the drive coil 5 through the relay contact 8a.
, And the drive coil 5 is driven by the discharge voltage to continuously push the objective lens 4 upward. On the other hand, the spindle motor 1 coasts even if the power is cut off, and a regenerative voltage is generated by the coasting rotation. Is supplied to the drive coil 5 through the. The discharge voltage of the capacitor 11 gradually decreases, and the regenerative voltage also gradually decreases as the inertial rotation of the spindle motor 1 gradually decreases. Accordingly, the driving force of the drive coil 5 is weakened, and the objective lens 4 is gradually pushed down by its own weight. Therefore, even if the power is cut off, the objective lens 4 can be prevented from dropping abruptly onto the disk 2, and the disk 2 can be prevented from being damaged.

In the above-described embodiment, when the power supply is cut off, the discharge voltage of the capacitor 11 is supplied to the drive coil 5 and the regenerative voltage accompanying the inertial rotation of the spindle motor 1 is supplied to the drive coil 5. Alternatively, only the discharge voltage of the capacitor 11 may be supplied to the drive coil 5, or only the regenerative voltage may be supplied to the drive coil 5.

[Effects of the Invention] As described above, according to the present invention, when the power supply is cut off, the drive coil of the objective lens is disconnected from the coil drive means, and the motor is disconnected from the motor drive means, thereby discharging the large-capacity capacitor. Since the voltage is supplied to the drive coil and the regenerative voltage generated by the inertial rotation of the motor is also supplied to the drive coil, the objective lens is rapidly pushed down from a position where the restoring force of the elastic member and its own weight are balanced. Can be prevented, and the disk can be prevented from being damaged.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of one embodiment of the present invention.
FIG. 2 is a schematic block diagram showing a main part of a conventional optical disk mastering device. In the figure, 1 is a spindle motor, 2 is a disk, 3,
7 is a drive amplifier, 4 is an objective lens, 5 is a drive coil,
6 is a spring, 8 is a relay coil, 8a to 8e are relay contacts, 9
Indicates a rectifier circuit, 10 and 12 indicate diodes, and 11 indicates a large-capacity capacitor.

Claims (1)

(57) [Claims] 1. An optical disk mastering apparatus in which a master disk is rotated by a driving force of a motor and a cutting operation is performed by irradiating a light beam to the master disk via an objective lens, wherein the objective lens has its own weight due to a restoring force of an elastic member. A coil for driving the drive coil, wherein a drive coil for localizing the object at a balanced position and moving the objective lens up and down against the balance is wound around the objective lens; A motor driving means for driving the motor; a large-capacity capacitor charged by a DC power supply; and disconnecting the drive coil from the coil driving means when power is turned off. To supply a driving coil to gradually lower the objective lens with a decrease in the discharge voltage. (1) disconnecting the motor from the motor driving means when the power is turned off, supplying a regenerative voltage generated by coasting rotation of the motor to the driving coil via the first switching means, A protection circuit for an optical disk mastering device, comprising: a second switching unit for weakening a driving force of a coil.