JPH0536612U - Optical disk player slider servo circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the convergence of tracking servo immediately after a track jump in pause, still, manual search, multi-speed, etc. [Structure] A jump signal is input to a monostable multivibrator 9. The output terminal of the monostable multivibrator 9 is connected to the power source via the series circuit of the resistor R10 and the resistor R11, and the connection point of the resistor R10 and the resistor R11 is the resistor R12.
Through the gate of the field effect transistor Q1. The drain of the field effect transistor Q1 is connected to the input side of the amplifier 7, and the source is connected to the ground. The monostable multivibrator 9 outputs a high level for a predetermined period longer than the jump period in which the analog switch S1, S2 or S3 to which the jump signal is input is closed to turn on the field effect transistor Q1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a slider servo circuit of an optical disk player, and more particularly to a slider servo circuit which prevents the servo from becoming unstable due to a track jump operation in pause, still, manual search, multi-speed and the like.

[0002]

[Prior Art]

 FIG. 2 shows an example of a slider servo circuit of a conventional optical disc player. As shown in the figure, the tracking error signal obtained from the optical pickup is input to the inverting input terminal of the operational amplifier 1 via the resistor R1 and also to the tracking logic circuit 4. The non-inverting input terminal of the operational amplifier 1 is connected to the ground, and the output terminal is connected to the inverting input terminal via the impedance Z2.

The output terminal of the operational amplifier 1 is also connected to the inverting input terminal of the operational amplifier 2 via the series circuit of the resistors R3 and R4. The connection point of the resistors R3 and R4 is connected to the ground by the series circuit of the capacitor C1 and the analog switch S1. The constant current sources I1 and I2 are connected to one end of a resistor R5 via analog switches S2 and S3, respectively, and the other end of the resistor R5 is connected to the inverting input terminal of the operational amplifier 2.

The non-inverting input terminal of the operational amplifier 2 is connected to the ground, and the output terminal of the operational amplifier 2 is connected to the ground via the series circuit of the tracking coil 3 and the resistor R6. The connection point A between the tracking coil 3 and the resistor R6 is connected to the inverting input terminal of the operational amplifier 2 via the parallel circuit of the resistor R7 and the capacitor C2.

The connection point A is connected to the inverting input terminal of the operational amplifier 5 via the resistor R8. The non-inverting input terminal of the operational amplifier 5 is connected to the ground, the output terminal is connected to the inverting input terminal via the impedance Z9, and is further connected to the input terminal of the slider logic circuit 6. The slider logic circuit 6 operates according to the mode instructed by the system microcomputer, and connects the supply constant current source I3 or the suction constant current source I4 to the input terminal of the amplifier 7 via the analog switch S4 or S5, respectively. The output voltage of the amplifier 7 is applied to the slider motor 8.

The tracking logic circuit 4 receives a jump signal in addition to the tracking error signal and turns on / off the analog switches S2 and S3.

In the above configuration, in the reproducing state of the laser disk, the tracking logic circuit 4 opens the analog switches S2 and S3, and the analog switch S1 is also opened, so that the tracking servo is on.

The tracking error signal is inverted and amplified by the impedance ratio of the resistor R1 and the impedance Z2, and further inverted and amplified by the resistance ratio of the resistor R3 and the resistor R4 in the series circuit, and appears at the connection point A. An electric current is supplied to the tracking coil 3. The capacitor C2 is provided for phase compensation. The tracking coil 3 is arranged in the magnetic field, and the objective lens integrated with it is moved so that the laser spot follows the signal pit train.

The voltage at the connection point A is inverted and amplified by the operational amplifier 5 and input to the slider logic circuit 6. The slider logic circuit 6 selects the analog switch S4 or S5 according to the sign of the DC component of the input signal to turn it on and off. The on / off duty ratio or the number of pulses of the analog switch changes according to the magnitude of the DC component of the input signal, and the current supplied through the analog switch is converted into a voltage by the amplifier 7 and applied to the slider motor 8. To be done.

By controlling the applied voltage of the slider motor 8 in this way, the slider motor 8 is driven so that the DC component of the voltage at the connection point A, that is, the DC component of the tracking error signal becomes zero, The slider on which the optical pickup is mounted is sent toward the outer circumference of the disk so that the laser spot of the optical pickup can follow the signal train.

In a mode in which track jumps such as pause and still are repeated, a pulse-shaped jump signal is output as shown in FIG. When the jump signal is input, the tracking logic circuit 4 closes the analog switches S2 and S3 back and forth, and supplies a reverse current to the tracking coil 3 back and forth. A forward / reverse voltage pulse in the period T appears in the voltage at the point A proportional to the tracking coil current shown in FIG. During this period, the analog switch S1 is closed and the tracking servo gain is lowered.

Due to such a pulse-shaped tracking coil current, the tracking servo with a reduced gain causes the laser spot to jump to an adjacent track. After the jump is completed, the analog switch S1 is opened, the tracking servo is applied, and the signal is reproduced.

FIG. 3C shows the voltage at point B. As shown in the figure, the voltage at point B appears as the integral of the voltage signal at point A. FIG. 3D shows the voltage at point C. The pulse E shown in the figure is a signal whose duty ratio is determined by the DC component of the input signal of the slider logic circuit 6, and acts so that the laser spot of the optical pickup follows the pit train of the signal.

The pulse D shown in the figure has the effect of kicking the slider motor in the same direction as the jump direction so as to enhance the responsiveness in the mode of repeating the track jump such as pause and still, and the slider logic circuit 6 Applied by the logic of.

[0015]

[Problems to be solved by the device]

 In the conventional slider servo circuit described above, when the analog switch S 1 is opened after the jump is completed and the tracking servo is returned to the original high gain, the slider motor is driven by the D or E pulse voltage as shown in FIG. 3D. However, there was a problem that the servo converged poorly and oscillated because of the applied voltage. In particular, this tendency was exhibited for an eccentric disk in which the slider movement was large.

The present invention has been made in view of the above points, and an object thereof is to provide a slider servo circuit of an optical disk player in which smooth convergence is performed after the end of a jump.

Another object of the present invention is to provide a slider servo circuit of an optical disk player in which the tracking servo is stable in a mode in which track jumps such as pause and still are repeated even for a disk with large eccentricity. Is.

[0018]

[Means for Solving the Problems]

 The slider servo circuit of the optical disk player of the present invention is configured so that a jump signal for activating a track jump operation is input to the monostable multivibrator, and the slider motor drive voltage is turned off by the output of the monostable multivibrator. It is characterized by that.

[0019]

[Action]

 According to the slider servo circuit of this invention, when the tracking servo is returned to the original high gain after the jump ends, the slider motor drive voltage is turned off by the action of the monostable multivibrator, so that the tracking servo is stabilized. Can be applied in a state.

[0020]

【Example】

 A tracking servo circuit according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment, and parts having the same functions as those shown in the conventional example are designated by the same reference numerals.

In the circuit of the embodiment, the jump signal is input to the monostable multivibrator 9 in addition to the tracking logic circuit 4. The output terminal of the monostable multivibrator 9 is connected to the power source via the series circuit of the resistor R10 and the resistor R11, and the connection point of the resistor R10 and the resistor R11 is connected to the gate of the field effect transistor Q1 via the resistor R12. Has been done.

The drain of the field effect transistor Q1 is connected to the input side of the amplifier 7, and the source is connected to the ground. The structure and operation of the other parts are the same as those of the conventional circuit shown in FIG.

In the above-mentioned configuration, in a mode in which track jumps such as pause and still are repeated, a jump signal is output from a microcomputer (not shown) as shown in FIG. 3A. When the jump signal is input, the tracking logic circuit 4 closes the analog switches S2 and S3 back and forth during the period T shown in FIG. 3 (b), and supplies the tracking coil 3 with a backward current before and after. Meanwhile, the analog switch S1 is closed and the tracking servo gain is lowered, and the laser spot jumps to the adjacent track.

When the jump signal is input, the monostable multivibrator 9 outputs a high level for a predetermined period longer than the 2T period shown in FIG. 3B to make the field effect transistor Q 1 conductive. During this period, the voltage applied to the slider motor 8 is 0, and the analog switch S1 can be opened to apply the servo in a stable state.

The period in which the monostable multivibrator 9 sets the applied voltage to the slider motor 8 to 0 is a short period during the jump, and the slider motor 8 is driven so as to respond to the tracking error signal during the period in which the tracking servo is applied. Thus, it is fully possible to converge the tracking error signal.

[0026]

According to the slider servo circuit of the present invention, the tracking servo can be stably turned on and off repeatedly during a jump operation of a laser spot such as manual search or multi-speed. Especially, the effect becomes great for a disc with large eccentricity.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a slider servo circuit according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an example of a conventional slider servo circuit.

FIG. 3 is a waveform chart of a signal showing an operation of the tracking servo circuit.

[Explanation of symbols]

 1 operational amplifier 2 operational amplifier 3 tracking coil 4 tracking logic circuit 5 operational amplifier 6 slider logic circuit 7 amplifier 8 slider motor 9 monostable multivibrator Q1 field effect transistor

Claims (1)

[Scope of utility model registration request] 1. A jump signal for starting a track jump operation is input to a monostable multivibrator, and a slider motor drive voltage is turned off by an output of the monostable multivibrator. Slider servo circuit.