JPH0450565Y2 - - Google Patents

Description

[Detailed explanation of the invention] "Purpose of the invention" (Industrial application field) This invention relates to an optical disc player for playing discs such as compact discs or optical video discs, and particularly relates to an optical disc player for playing discs such as compact discs or optical video discs. The present invention relates to an optical pickup focus search device used in a player.

(Prior art) As an optical pick-up focus search device used in an optical disc player,
For example, there is a device configured as shown in FIG.

The conventional focus search device shown in FIG. 3 includes a focus coil 1 for vertically moving an objective lens provided on an actuator, an amplifier 2 for amplifying the voltage for exciting the focus coil 1, A capacitor C1 that supplies voltage to the amplifier 2 via a switch S3 that is turned on during focus search, current sources 3 and 4 for charging or discharging this capacitor C1, and a switch S that switches between the current sources 3 and 4.
1 and S2, and a flip-flop circuit 5 that controls on/off of the switches S1 and S2.
is provided.

Furthermore, this focus search device is provided with a focus search signal that causes the flip-flop circuit 5 to perform an inverting operation, and a focus search signal that causes the flip-flop circuit 5 to perform a reset operation or to turn on/off the switch S3 to generate a focus signal that becomes "H" during a focus search. Focus ON controls switch S4, which turns on and off the supply of focus search ON signal and focus error signal to focus coil 1.
signals are applied respectively.

Therefore, as shown in Fig. 4, when the optical pickup is stopped, both the focus ON signal and the focus search ON signal are "L".
Switches S3 and S4 are off, flip-flop circuit 5 is reset, switch S1 is off, switch S2 is on, and capacitor C1 has a negative voltage. After that, when the focus search is started, the focus search ON signal becomes "H" and the switch S3 is turned on. On the other hand, the flip-flop circuit 5 operates inverted by the focus search signal, turning on the switch S1 and turning on the switch S2.
is off. As the switch S1 is turned on, a positive voltage is applied to the capacitor C1, and this voltage is applied to the amplifier 2 via the switch S3.
is supplied to energize the focus coil 1 and slowly raise the actuator. Then, at focus zero cross, the focus search ON signal is set to "L" and switch S3 is turned off, while
Set the focus ON signal to “H” and switch S.
4 is turned on, and focus is applied using a focus error signal.

(Problem to be solved by the invention) However, in the conventional focus search devices described above, other than those in which the actuator is supported by a spring (for example, the shaft sliding method), when the optical pick-up stops operating, the objective lens The actuator to which the actuator is attached is lowered to the lowest end, and is in a standby state with the lower surface of the actuator resting on a cushion provided on a plate (small board). Therefore, if the actuator is left in this state for a long time, depending on the environmental conditions such as temperature and humidity, or the material of the cushion, there is a risk that the actuator may stick to the cushion. Due to this sticking phenomenon, during focus search, the voltage vs. movement amount of the actuator becomes as shown in Figure 5, and in the first focus search, no focus is applied, and several focus searches are performed. It was necessary to do it.

This invention was made in view of the above-mentioned points, and its purpose is to provide a focus search device that improves responsiveness during startup due to the actuator sticking to the cushion. It is in.

"Structure of the invention" (Means for solving the problem) In the focus search device according to this invention, an actuator provided with an objective lens in an optical pickup is placed on a cushion provided on a plate in a standby state. In the optical disc player, a focus coil for moving the actuator up and down, a capacitor for applying a focus search voltage to the focus coil, a first switch for charging the capacitor with a positive voltage, and a first switch for charging the capacitor with a positive voltage. a second switch for charging a negative voltage; a switching means for switching and controlling the first and second switches according to a focus search signal; The problem is solved by providing means for controlling the switching means so that the switch is in the operative state and the second switch is in the inoperative state.

(Function) When the optical pickup stops operating, the first switch is turned on and the second switch is turned off.
A positive voltage is charged to the capacitor C1, and this charged voltage is supplied to the focus coil when the focus search operation is started by the focus search ON signal, and the actuator is once rapidly raised and separated from the cushion to release the stuck state. do. Thereafter, a normal focus search operation is performed using a focus search signal. That is, the first switch is turned off and the second switch is turned on, the capacitor C1 is discharged with a positive voltage and conversely charged with a negative voltage, and the actuator is sufficiently powered by supplying this negative voltage to the focus coil. After dropping, turn on the first switch and turn off the second switch to discharge the negative voltage to the capacitor C1 and charge the positive voltage, and supply the voltage of this capacitor to the focus coil to turn the actuator on. Slowly rise and apply focus at focus zero cross.

(Example) An example of the focus search device according to this invention will be described based on FIGS. 1 and 2. 1st
The figure is a circuit diagram showing the overall configuration, and FIG. 2 is an operation explanatory diagram. Note that the same parts as those of the conventional focus search device shown in FIG. 3 described above are indicated by the same reference numerals.

In the figure, reference numeral 1 denotes a focus coil, which is provided on an actuator and serves as a drive source for vertically moving an objective lens provided on the actuator. 2 is an amplifier that amplifies the voltage from the capacitor C1 and supplies it to the focus coil. 3 and 4 are positive and negative current sources for charging or discharging the capacitor C1. 5 is a flip-flop circuit, which has current sources 3 and 4.
It controls the on/off of switches S1 and S2. The flip-flop circuit 5 performs an inversion operation in response to a focus search signal generated at the timing shown in FIG. 2, and turns on and off the switches S1 and S2 each time. In addition, this flip-flop circuit 5 receives a focus search ON signal that becomes "H" during focus search, and a focus search ON signal that becomes "H" during focus search.
It has a NOR circuit 6 for "resetting" with the focus ON signal that becomes "H", and furthermore,
It is configured to be "set" when the focus search ON signal is "H".

When the focus search ON signal is "H", it turns on the switch S3 and supplies the voltage of the capacitor C1 to the amplifier 2. Also, the above focus
When the ON signal is “H”, switch S4 is turned on,
It is configured to supply a focus error signal to the focus coil 1.

With the above configuration, when the optical pickup is stopped, both the focus ON signal and the focus search ON signal are "L", so
As shown in FIG. 2, switches S3 and S4 are turned off. At this time, the flip-flop circuit 5
Since both inputs of the NOR circuit 6 are "L", the switch is "reset", so the switch S1 is turned on.
Switch S2 is turned off and capacitor C1 is
A positive voltage is applied and it is being charged. In addition,
At this time, since the switch S3 is off, the focus search voltage charged in the capacitor C1 is not applied to the focus coil 1.

When the focus search is started, the focus search ON signal becomes "H", turning on the switch S3, and the positive focus search voltage charged to the capacitor C1 is applied to the focus coil 1, and the focus search ON signal becomes "H". The actuator, which was placed on top of it, suddenly rises. At this time, even if the contact surface of the actuator sticks to the cushion for some reason, it can be released from the stuck state. On the other hand, the flip-flop circuit 5 changes from being "reset" by the NOR circuit 6 to the "set" state.
It is inverted by the first focus search signal, turns off the switch S1, turns on the switch S2, discharges the capacitor C1, lowers the voltage applied to the focus coil 1, and lowers the actuator. Thereafter, when the actuator is sufficiently lowered, the flip-flop circuit 5 is inverted again by the second focus search signal, turning on the switch S1, turning off the switch S2, and charging the capacitor C1. The focus search voltage of the capacitor C1 excites the focus coil 1 and slowly raises the actuator to reach the focus zero cross point. At this focus zero cross, if the focus search ON signal is set to "L" and the focus ON signal is set to "H", the switch S
3 is off, switch S4 is on, and a focus error signal is supplied to focus coil 1 via switch S4, allowing focus to be applied.

"Effect of the invention" According to the focus search device according to this invention, since the single actuator is raised rapidly immediately before starting the regular focus search operation, even if the actuator is stuck to the cushion, It can be easily released from the stuck state. Furthermore, since this operation can be performed in an extremely short time, it is possible to reliably focus without significantly prolonging the focus search time, which is extremely effective in practice.

[Brief explanation of drawings]

1 and 2 show an embodiment of the focus search device according to this invention, FIG. 1 is a circuit diagram, and FIG. 2 is an operation explanation for explaining the operation of FIG. 1. It is a diagram. Figures 3 to 5 show conventional examples, with Figure 3 being a circuit diagram and Figure 4 being a circuit diagram.
The figure is an operation explanatory diagram for explaining the operation of Fig. 3,
FIG. 5 is a characteristic diagram showing the focus search voltage versus the amount of movement of the actuator. 1...Focus coil, 2...Amplifier, 3,
4...Current source, 5...Flip-flop circuit, 6
...NOR circuit, S1 to S4...switch.

Claims (1)

[Claims for Utility Model Registration] In an optical disk player in which an actuator provided with an objective lens in an optical pickup is placed on a cushion provided on a plate in a standby state, a focus coil for vertically moving the actuator; , a capacitor that applies a focus search voltage to the focus coil, a first switch that charges the capacitor with a positive voltage, a second switch that charges the capacitor with a negative voltage, and the first switch that charges the capacitor with a negative voltage. , a switching means for switching and controlling the second switch in accordance with a focus search signal; when the optical pickup operation is stopped and before the focus search is started, the first switch is in an operating state;
A focus search device comprising means for controlling said switching means so that said second switch is in an inoperative state.