KR910006666B1 - Track-on delaying circuitry of cdp - Google Patents

Abstract

The circuit closes the focus servo and then closes the tracking servo after certain time to stabilize the focus servo of the optical disk. The circuit includes a focus error comparator (18) for generating the focus error signal, a modulated wave form comparator (19) for generating the modulated wave form signal by receiving the output signal of the RF amplifier (12), a tracking controller for selecting the open loop or the closed loop of auto tracking mechanism according to the focus error and modulated wave form signal and for generating the tracking selection signal, and a tracking switch for selecting the control loop of the auto tracking as the open loop or the closed loop.

Description

Track-on delay circuit of optical disc player

1 is a circuit diagram according to the present invention.

2 is a waveform diagram of each part according to the present invention.

3 is a circuit diagram of an embodiment according to the present invention.

* Explanation of symbols for main parts of the drawings

10: System Controller 11: Optical Pickup

12: RF amplifier 13: Focus error detection and amplification unit

14: focus start signal generator 15: tracking error detection and amplifier

16: Focus Servo 17: Tracking Sub

18: focus error comparator 19: modulated waveform comparator

20: tracking control unit 21: delay circuit unit, SW1, SW2: first, second switch

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device capable of writing or reading data by operating a disc-shaped optical disc (Disc). In particular, the tracking servo is closed after closing the focus servo. It is about the circuit which can be done.

In general, the servo requires a stabilization time, and the tracking and focus servos are closed loops to play.

In the conventional compact disc player (hereinafter referred to as CDP), the focus servo and tracking servo operation become a close loop, the focus servo becomes a closed loop, the tracking servo is closed loop first, and then the focus loop is closed. Close the servo. The two operating states have a problem in that the servo operation is impossible due to destruction of servo linearity according to the surrounding environment.

Accordingly, an object of the present invention is to provide a track-on delay circuit of an optical disc reproducing apparatus that can close a tracking servo after a predetermined time after closing the focus servo to stabilize the focus servo of the optical disc.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a circuit diagram according to the present invention, which includes a system controller 10, an optical pickup 11, an RF amplifier 12, a focus error detection and amplification unit 13, a focus start signal generator 14, and a tracking error detection. And a focus error for generating a focus error comparison signal by determining a focus error state of an output signal of the amplifying unit 15, the focus servo 16, the tracking servo 17, and the focus error detection and amplifying unit 13. A comparison unit 18 and a modulation waveform comparison unit 19 for generating a modulation waveform comparison signal by determining a state of a modulation wave signal which is an output signal of the RF amplifier 12 generated by modulating a laser beam on a disk; A tracking control means for determining an open loop or a closed loop state by determining a focus error comparison signal and the modulation waveform comparison signal, and generating a tracking selection signal; and a state of auto tracking by the tracking selection signal. Constitute the tracking switching means for switching a loop or closed loop.

2 is an angle waveform diagram according to the present invention, where (a) is a focus start signal (1), (b) is a focus error signal (2), (c) is a modulation wave signal (3), and (d ) Is the focus error comparison signal (4), (e) is the modulation waveform comparison signal (5), (f) is the tracking control signal (6), and (g) is the laser diode (LD) power state signal of the APLC. (9), (h) is the focus selection signal (7), and (i) is the tracking selection signal (8).

3 is a circuit diagram of an embodiment according to the present invention, where 3a is an embodiment of the focus error comparator 18, 3b is an embodiment of the modulated waveform comparator 19, and 3c is a tracking control. 20 is an embodiment of the delay circuit section 21. In FIG.

Based on the above configuration, the present invention will be described in detail with reference to FIGS. First, in the system controller 10, when the play mode needs to be changed in the stop mode, for example, when the external play button is pressed, the first switch SW1 is operated so that the first switch SW1 is operated. (h) Like the waveform, the focus select signal 7 changes from low to high. Thus, the focus start signal 1, which is an output signal of the focus start signal generator 14, generates a triangular wave like the waveform of FIG.

This occurrence raises the objective lens of the optical pick-up 11 to bring it within a range where Auto focus is possible.

As the objective lens reaches its range, a signal modulated by a laser beam on a disk detects and amplifies a focus error through a focus error detection and amplification unit 13, and modulates the signal through the RF amplification unit 12. The signal is amplified to generate a focus error signal 2 and a modulated wave signal 3, such as the waveforms of FIGS. 2B and 2C, respectively. The RF amplifier 12, the focus error detection and amplification unit 13, the focus start generator 14, the tracking error detection and amplification unit 15, the focus servo 16, and the tracking servo 17 are Since it is a general meeting in the CDP, circuits and operations are omitted or briefly explained.

When the focus error signal 2 is input to the focus error comparator 18 and processed, referring to FIG. 3A, the focus error signal 2 is transferred to the third band pass filter. Through the configured resistors R2 and capacitors C2 and C3, only the focus error generated at the start of focus in the initial state is passed and input to the input terminal of the first comparator COM1.

When the magnitude of the focus error signal 2 is compared with the reference voltage and is smaller than the reference voltage, a low signal such as the waveform of FIG. 2 (d) which is the focus error comparison signal 4 is output from the first comparator COM1. . When the focus start signal 1 is generated like the dotted line of the waveform of FIG. 2 (a) and the objective lens is raised higher, the focus error signal 2 is formed by the dotted line like the waveform of FIG. 2 (b). Becomes That is, the focus error signal 2 should be smaller than the reference voltage.

In addition, referring to FIG. 3B, an operation state in which the modulated wave signal 3 is input to the modulated waveform comparator 19 and processed is described. Through a predetermined amplification, the cutoff voltage passes through the diode D2 close to zero.

The modulated wave signal 3 passing through the diode D2 is subjected to low pass filltering through the resistors R3 and R7 and the capacitor C4 and input to the input terminal of the second comparator COM2. When the second comparator COM2 compares the magnitude of the modulation wave signal 3 with the reference voltage and becomes larger than the reference voltage, a high signal such as the waveform of FIG. 2 (e), which is the modulation waveform comparison signal 5, is output. .

The operation state in which the high signal is processed by inputting the tracking control unit 20 will be described with reference to FIG. 3C, where the high signal is inputted by the AND gate G2 to the first input terminal, and the focus error occurs. The comparison signal 4 is input to the second input terminal of the AND gate G2 as a signal inverted through the inverter G1.

The high signal is output to the output terminal of the AND gate G2, and is input to the system controller 10, and is input to the input terminal D of the flip-flop FF. At the moment when the system controller 10 becomes high, the contact point (B) of the first switch SW1 becomes low and is changed to the contact point (A) of the first switch SW1 so that autofocusing is possible. Then, the output signal of the gate G2 is latched through the flip-flop FF.

Therefore, the high signal, which is the tracking control signal 6, is output from the output terminal Q of the flip-flop FF, which is the same as the waveform of FIG.

The tracking control signal 6 is input to the delay circuit section 21 while maintaining the state until the stop mode. The delay circuit unit 21 will be described with reference to FIG. 3D (3d). When the tracking control signal 6 is an integrating circuit, the delay of the time constants R1 and C1 is through the resistor R1 and the capacitor C1. The signal is delayed and input to the inverting input terminal of the third comparator COM3.

The diode D1 connected between the resistor R1 is for discharging the charging signal.

The third comparator COM3 compares the delayed tracking control signal 6 with the reference voltage to stabilize the focus servo 16 during the delay by the time constants R1 and C1 and the reference voltage. After the servo 16 is stabilized, the output of the third comparator COM3 becomes a low signal.

The low signal is a tracking selection signal 8, which closes the tracking and becomes an auto tracking state, and the (D) contact point of the second switch SW2 changes to the (C) contact point. In other words, the auto tracking state is a play mode.

If the disk motor is stopped, the laser diode (LD) power is turned on from the system controller 10 by using the laser diode (LD) power state signal (9) generated from the ALPC line (Automatic Laser Power Contoller). Turn it off.

The laser diode (LD) power state signal (9) is the same as the waveform of FIG. 2 (g), and after initializing the focus error signal (2) and the modulation wave signal (3) in the laser diode (LD) power off state. The focus selection signal 7 is input from the low to the high to the tracking control unit 20 as shown in the waveform of FIG.

The low signal input to the tracking control unit 20 is inputted to the clock terminal CK of the flip-flop FF of FIG. 3C and a low signal through the output terminal Q of the flip-flop FF. To latch.

When the low signal is input to the delay circuit unit 21 as the tracking control signal 6, the charge that has been charged in the capacitor C1 in the portion of FIG. 3C is discharged through the diode D2, so the delay time becomes very short. .

As described above, after closing the focus servo for stabilizing the focus servo of the optical disk, the tracking servo can be closed for a predetermined time, thereby improving the reliability of the product which can prevent the destruction of the servo. .

Claims (3)

The system controller 10, the optical pickup 11, the RF amplifier 12, the focus error detection and amplification section 13, the focus start signal generator 14, the tracking error detection and amplification section 15, and the focus surge A reproducing apparatus for reading information of a disc-shaped optical disc having a beam 16 and a tracking servo 17, wherein the focus error detection signal is determined by determining a focus error state of the focus error detection and amplification unit 13 output signal. A focus error comparator 18 for generating a signal and a modulated waveform comparator for generating a modulated waveform comparison signal by judging a state of a modulated wave signal that is an output signal of the RF amplifier 12 generated by modulating a laser beam on a disk (19), tracking control means for determining an open loop or a closed loop state by determining the focus error comparison signal and the modulation waveform comparison signal, and generating a tracking selection signal, and the tracking selection signal. And a tracking switching means for switching the state of auto tracking to an open loop or a closed loop by means of a track on delay circuit of the optical disc reproducing apparatus. 2. The track-on delay circuit of claim 1, wherein the tracking control means comprises delay means for delaying predetermined tracking for stable autotracking when the tracking selection signal is generated in the closed loop in the open loop state. The track on of the optical disc reproducing apparatus according to claim 2, wherein the delay means delays the time from the close loop to the stable loop state when the focus servo 16 becomes the closed loop from the open loop state. Delay circuit.

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