JPS61236033A - Optical disk device - Google Patents

Abstract

PURPOSE:To reduce cost by detecting voltage level of +VCC1 and -VCC2, and cutting off a focus controlling signal when either of them does not reach specified voltage and preventing collision of an optical system device against the disk face at the time of turning on and off of a power source. CONSTITUTION:A +VCC1 detecting circuit 1 detects that a controlling circuit 5 arrived at a voltage or above by which the circuit can operate normally, and a -VCC2 detecting circuit detects that the controlling circuit 5 is at a voltage or above by which the circuit can operate normally, and supplies detection output. When the two are satisfied, output of an AND circuit, that is, a controlling signal 8 goes to high level, and focus controlling signals 9a, 9b detected by an optical system 4 and processed by the controlling circuit 5 are transmitted to an actuator driving circuit 6. When the controlling signal 8 is low level, the signal of the controlling circuit 5 is not transmitted to the actuator driving circuit 6, and both ends of an actuator 7 become the same potential and current does not flow. Thus, a protective circuit at the time of power source on and off of an optical disk device can be realized with very small number of parts.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical disk device having an optical system control device (hereinafter referred to as an actuator) using electromagnetic induction, and particularly relates to a protection circuit for turning on and off the power of the optical disk device. It is something.

The optical system of a conventional optical disk device uses an actuator that creates a solenoid in a magnetic circuit and controls the solenoid by passing a current through the solenoid in order to improve responsiveness. As a power supply for the control system, oV is used to increase the stability of the control system.
It is often driven by two power sources, plus and minus, based on .

In such an optical disk device, it is extremely difficult to ensure that the positive power supply (hereinafter referred to as +■..1) and the negative power supply (hereinafter referred to as -vcc2) rise and fall at the same time when the power is turned on or off. This is difficult, and the control signal based on ov is drawn to the side that rises earlier. As a result, an excessive current flows through the actuator when it is turned on or off, causing the optical system to collide with the disk surface.

For this reason, in the past, a timer and relay were used to set the time from when the device was switched on until the power stabilized, and then the relay turned on the power to the actuator drive circuit after stabilization. . When I turned off the power, I did the opposite.

Problems to be Solved by the Invention However, conventional protection circuits using relays have the drawbacks that the timer, relay, power supply and circuit for the relay are complicated and the cost is not high.

Means to Solve the Problem The present invention detects the voltage levels of +vcC1 and -vcc2, and if either one does not reach a specified voltage, the focus control signal is cut off and no current flows to the actuator. This prevents the optical system from colliding with the disk surface when the power is turned on and off.

Effects According to the configuration of the present invention described above, the current based on the control signal flows through the actuator only after both power supply voltages reach a specified voltage, so that the optical system device does not hit the disk surface. In addition, it has the advantage that the circuit configuration is greatly simplified, and furthermore, it can be easily integrated into an IC.

Embodiment An embodiment of the present invention will be explained with reference to FIG. In the figure, 1 is the +vca1 detection circuit, +■. . 1 detects that the voltage has reached a voltage higher than that at which the control circuit 5 can operate normally, that is, +4V or higher in this case, and issues a detection output. In addition, in the 2ba1■oC2 detection circuit, -vCc2 is higher than the voltage at which the control circuit 5 can operate normally, that is, -4 here.
It detects that it is less than v and issues a detection output. When both of these conditions are satisfied, the output of the AND circuit 3, that is, the control signal 8 becomes high level, and the focus control signal 9a is detected by the optical system 4 and processed by the control circuit 5.

9b is transmitted to the actuator drive circuit 6.

When the control signal 8 is at a low level, the signal from the control circuit 6 is not transmitted to the actuator drive circuit 6, and both ends of the actuator 7 are at the same potential and no current flows.

FIG. 2 shows a specific embodiment of the present invention, and FIG. 3 shows its characteristics for explaining its operation. +voo1 detection circuit 1 operates to turn on transistor Q1 when +voc1 becomes 4V or more through resistors R1 and R2. -vcc
2 detection circuit 2 similarly operates to turn on transistor Q4 when -v0°2 becomes 14V or less through resistors R8 and R9. When transistor Q1 is on, transistor Q2 is turned off, and when transistor Q2 is on, transistor Q3 is turned off. Transistor Q2. The control signal 8 becomes high level only when both Q3 are off, that is, when +vc01 is 4V or more and =vcc2 is 14V or less.

Control signals 9a, 9b are supplied to transistors Q8. Q9゜Q10
1011% resistance R16ff R171R18R191R
20 is supplied to the differential amplifier of the actuator drive circuit 6. Transistor Q1゜, Qll, resistance R
Reference numeral 19 and R2o denote a current source that supplies the same current as the power source composed of diodes D1 to D4 and resistors R13 to R1.

If the control signal 8 is at a high level, the transistor Q5 is turned on and the transistor Q6 is turned off, so that the differential amplifier operates normally and the control signals 9a and 9b are passed to the next stage amplifier Q12. Tell Q13. control signal 8
When is at a low level, transistor Q5 is turned off and transistor Q6 is turned on. Therefore, the current source Q of the differential amplifier
1 o.

Qll is turned off and the differential amplifier Q8. The collector of Q9 is at the same potential as the emitter of transistor Q7, and the amplifier Q
12. Q13 is cut off, amplifier Q12゜Q13
Both collectors are OV. Therefore, the control signals 9a and sb are not transmitted to the next stage, and since the potentials are the same, no current flows through the actuator 7.

Due to the above operation, +V and - when the power is turned on and off.
A circuit can be configured to cut off the current flowing to the actuator 7 when either one of the voltages vca2 does not reach the regular voltage c1 and a regular control signal is not obtained.

In Figure 3, +v, , = o ~ 1.5v is the control signal 8
increases because +v0゜1 is low, so the pace potential of transistor Q2 is low and transistor Q2 is not turned on sufficiently.If the value of resistor R4 is increased to 1oOKΩ, control signal 8 becomes less than 1■, and resistor R5,R
There is no problem because the transistor Q5 is not turned on due to the division by R11 and R12. If the resistor R4 is removed, the transistor Q2 may turn on due to leakage current, resulting in unstable operation.

Effects of the Invention As described above, according to the present invention, a protection circuit for turning on and off the power of an optical disk device can be realized with a very small number of parts. Furthermore, the circuit configuration is suitable for IC implementation, and can be realized without increasing cost, which is very advantageous in practice.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an optical disc device according to an embodiment of the present invention, FIG. 2 is a specific circuit diagram of the same device, and FIG. 3 is a characteristic diagram for explaining the operation of the embodiment. 1...+vCC1 detection circuit, 2......-
■. . 2 detection circuit, 3...AND circuit, 6...
...Control circuit, 6...Actuator drive circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (1)

[Claims] It is equipped with a control means for performing optical system control such as focus control or tracking control of the recording/reproducing unit on the optical disk by electromagnetic induction, and the above control is performed only when the power supply voltage of the control means is equal to or higher than a predetermined voltage. An optical disc device characterized in that the optical disc device is configured to supply a control signal for the means to an electromagnetic induction drive circuit.