KR890015217A - Focus Servo Circuit and Method for Optical Disc Players of Different Kinds - Google Patents

Abstract

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Description

Focus Servo Circuit and Method for Optical Disc Players of Different Kinds

Since this is an open matter, no full text was included.

1 is a focus open loop characteristic diagram of a focus servo. 2 is a circuit diagram of the present invention.

Claims (4)

In another type of optical disc reproducing apparatus having a rotary motor 29, a transfer motor 28, and an optical pickup unit 30, mounted on a pickup for converting a light quantity signal reflected from the disc into a current which is a conventional signal. The first light receiving element piece PD1 and the second light receiving element piece PD2 symmetrically opposed to the first light receiving element piece PD1 for converting the optical signal reflected from the disk into a current which is an electrical signal, A first current-voltage (hereinafter referred to as IV) converter 13 for converting the current signal of the first light receiving element piece PD1 into a voltage signal, and the current signal of the second light receiving element piece PD2 as a voltage signal. A second IV converter 14 for converting, a first addition circuit 15 serving as a means for generating a high frequency signal by adding voltage signals of the first and second IV converters 13 and 14, Serves as a means for compensating for the modulation transfer of the RF signal of the first addition circuit 15 RF waveform compensation means, error detection means for differentially amplifying the voltage signal of the first IV converter 13 and the voltage signal of the second IV converter 14 to detect a focusing error, and the RF waveform compensation means It monitors the presence or absence of RF signal applied from the output terminal of the controller and generates off-cell and frequency characteristic control signals by recognizing the type of disk and the presence of the disk. The system controller 18 controls each part of the system, the actuator 25 mounted on the laser pickup for driving the objective lens, and the focus driving signal of the system controller 18 to some extent focus the light beam. A controller 26 which is a focus for generating a lens driving signal for raising the objective lens so as to enable a focus servo operation so as to be engaged; and the system controller 18 The off-cell correction means for correcting the off-cell voltage of the focus error signal detected by the error detection means by the off-cell control signal of the control unit and generating a first correction signal, and the frequency characteristic control signal of the system controller 18. A frequency characteristic and error correction means for correcting a frequency characteristic and an error amount of the first correction signal of the off-cell correction means to generate a focus correction signal, and a controller that is the focus correction signal of the frequency characteristic and error correction means. And a power amplifier (27) for power amplifying the focus drive signal of (26) at a predetermined ratio and supplying the actuator to the actuator (25). The second variable resistor (VR2) according to claim 1, wherein the off-cell correction means is connected to the first power source (Vcc) and the third power source (-Vcc) to generate a first off-cell compensation voltage according to the manufacturer's adjustment. ), A third variable resistor VR3 connected between the first power source Vcc and the third power source (-Vcc) to generate a second off-cell compensation voltage by the manufacturer's adjustment, and the second off-cell compensation A second addition circuit 19 for input-adding a voltage and a third off-cell compensation voltage and the focusing error or input-adding the third off-cell compensation voltage and the focusing error to correct an off-cell voltage of a focusing error; And a first switching means which mutes the second off-cell correction voltage of the second variable resistor (VR2) by switching by an off-cell control signal of the controller (18). A first filter (21) composed of resistors (R24, R25) and capacitor (C4) as a means for compensating the frequency characteristics of the first correction signal from the second addition circuit (19); A second filter composed of resistors R26 and R27 and capacitor C5 as a means for compensating the frequency characteristics of the first correction signal of the second addition circuit 19 connected in parallel with the first filter 21; 22) second switching means for controlling parallel connection of the first filter 21 and the second filter 22 by switching by the frequency characteristic control signal of the system controller 18; Circuit comprising the error and phase correction means serving as a means for generating a focusing correction signal by compensating the focus error amount and phase of the second correction signal input through the filter (21). An optical pickup unit 30 for reading information contained in the disk, a transfer motor 28 for reciprocating the optical pickup unit 30 in the radial direction of the disk, a rotary motor 29 for rotating the disk, In another type of optical disc reproducing apparatus having a rotary motor 29 and a transfer motor 28 and an optical pickup unit 30, the optical disc reproducing apparatus is mounted on a pickup to convert a light quantity signal reflected from the disc into an electric signal current. The first light receiving element piece PD1, the second light receiving element piece PD2 symmetrically opposed to the first light receiving element piece PD1 for converting the optical signal reflected from the disk into a current which is an electrical signal, The first current-voltage (hereinafter referred to as IV) converter 13 for converting the current signal of the first light receiving element piece PD1 to the voltage signal and the current signal of the second light receiving element piece PD2 are converted into a voltage signal. Of the second IV converter 14 and the first and second IV converters 13 and 14 RF waveform compensation acting as a means for compensating the modulation transfer of the RF circuit of the first adding circuit 15 and the first adding circuit 15 as a means for generating a high frequency signal by adding a pressure signal. Means, error detection means for differentially amplifying the voltage signal of the first IV converter 13 and the voltage signal of the second IV converter 14 to detect a focusing error, and an output terminal of the RF waveform compensating means, It monitors the presence or absence of RF signal from the system and recognizes the type of disk and the presence of the disk to generate off-cell and frequency characteristic control signals.The playback system generates the focus drive signal and rotates the motor, the transfer motor and the playback device. A system controller 18 for controlling the part, an actuator 25 mounted on the laser pickup for driving the objective lens, and a focus drive signal of the system controller 18. By the control path 26 and the off-cell control signal of the system controller 18, which is a focus for generating a lens driving signal for raising the objective lens to enable the focus servo operation to the extent that the light beam is focused to some extent. Off-cell correction means for correcting the off-cell voltage of the focus error signal detected by the error detection means to generate a first correction signal, and the off-cell correction means according to the frequency characteristic control signal of the system controller 18. A frequency characteristic and error correction means for correcting a frequency characteristic and an error amount of the correction signal to generate a focus correction signal, a focus correction signal of the frequency characteristic and error correction means, or a focus drive signal of the controller 26 which is the focus. Reproducing different types of optical discs having a power amplifier 27 for amplifying the power at a predetermined ratio and supplying the actuator 25 to the actuator 25 In this regard, the system controller 18 may have a difference between the first disk and the second disk (<OBP <b) and a point between the second disk and the third disk (b <OBP <) and the third disk. The transfer motor 28 is controlled to sequentially scan the light beams to random points (the <OBP) in the disc, and check whether the light beams reflected on the disc are received by the optical pickup unit 30 to receive the first and second discs. Recognizing that a wide range is first received at an arbitrary point in between is "a first disk of size" and a second disk of "I" size when a light beam is first received at a random point between said second disk and a second disk. When the light beam is first received at an arbitrary point in the third disk, it is recognized as a third disk of "large" size. If the light beam is not received at any of the three points, the disk is not recognized and the operation is stopped. And the off-cell control signal and the frequency characteristic control signal according to the type of the disc, when corrected as the first disc or the second or third disc, correct the focus error, and then control the transfer motor 28. Moving the optical pickup unit 30 so as to scan a beam of light in the lead-in area to read and reproduce the information recorded on the disk. ※ Note: The disclosure is based on the initial application.