KR20000033646A - Apparatus for preventing vibration of lens of optical pick-up - Google Patents

Abstract

PURPOSE: An apparatus for preventing the vibration of lens is provided to compensate for biasing of lens generated searching operation of an optical recorder/reproducer in order to prevent the vibration of the lens. CONSTITUTION: An apparatus for preventing the vibration of lens comprises: an optical pick-up(20) for reading the information from a disk; a tracking error detector(22) for detecting the tracking error from an output signal of the optical pick-up; a micom(34) for generating a control signal corresponding to a search mode and a recording/reproducing mode; an offset detector(28) for detecting an offset voltage which is proportional to a biasing degree of the lens from the tracking error signal inputted from the tracking error detector in the search mode; and a tracking actuator driver(32) for controlling a tracking actuator driving the lens so as to compensate for the offset voltage in the search mode.

Description

Apparatus For Protecting Lens Vibration Of Optical Pick-up

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk drive device, and more particularly, to an optical pickup lens vibration preventing device capable of preventing vibration of a lens caused by inertia during a pickup movement during a search operation of an optical recording / reproducing device.

Recently, with the development of optical discs such as compact discs (CDs) and digital versatile discs (DVDs), high speed drive devices capable of driving them have been released. In such an optical disc drive device, it is necessary to improve the servo technology in order to realize high speed.

In general, an optical recording / reproducing apparatus includes an optical pickup for irradiating a light beam to a disk and converting the reflected light beam into an electrical signal, and an optical pickup servo for performing focusing, tracking, and sled operations of the optical pickup. .

The optical pickup includes an actuator for driving the objective lens to perform the focusing operation and the tracking operation together with the optical system in a wire method or a plate spring method. Here, the focusing operation of the actuator means moving the objective lens in the vertical direction so that the light spot caused by the objective lens falls within the depth of focus in the signal track of the disc. Tracking also means moving the objective lens in left and right directions so that the light spot by the objective lens follows the center of the signal track of the optical disc. Then, the optical pickup performs the disc search, recording and playback operations while moving in the radial direction (ie, the horizontal direction) of the disc by the movement of the sled. The optical pickup servo includes a focusing and tracking servo that controls the focusing and tracking operation of the optical pickup, and a sled servo that controls the movement of the sled.

When the search operation is performed in the optical recording / reproducing apparatus, the tracking servo is first turned off, and then the slide motor is driven to move the pickup to a desired position, and the tracking servo is turned on again. The most important factor in this search operation is to move to the target track quickly and accurately to perform tracking servo. However, since the tracking actuator is turned off in the operation section of the slide motor, the lens is biased in the direction opposite to the movement direction of the pickup due to inertia and vibration of the lens occurs. This is almost no visual difference, but from the signal point of view, it is a factor that causes a large tracking error caused by lens skew and vibration. The above-mentioned problems will be described in detail with reference to the accompanying drawings.

1 is a view illustrating a position shift state of a lens due to a general optical pickup movement.

In FIG. 1, the optical pickup 10 includes an actuator 12 that drives the lens 14 to perform a focusing operation and a tracking operation in a wire or plate spring manner. When the pickup 10 is moved by acceleration of the slide motor during the search operation of the optical recording / reproducing apparatus, the lens 14 is biased from the position of a to the position of b by inertia. In addition, even when the slide motor is decelerated, the lens 14 is biased to the position c by inertia. Due to this, the lens 10 mounted on the wire or plate spring actuator 12 vibrates and the lens 10 continues to vibrate for some time after the slide motor is turned off and the pickup 10 stops. do. Due to the vibration of the lens 10, the tracking error signal becomes large, and it takes more time to perform the tracking servo after the tracking servo is turned on, and sometimes the tracking is caused by moving away from the target track. There is a problem that cannot be done.

Accordingly, it is an object of the present invention to provide an anti-vibration device for an optical pickup lens that can prevent lens vibration by compensating for lens distortion occurring during the search operation of the optical recording / reproducing apparatus.

Another object of the present invention is to provide an anti-vibration device of an optical pickup lens that can perform a search operation more quickly and accurately by preventing lens vibration due to optical pickup movement.

1 is a view showing the movement position of the objective lens on the pickup when the pickup is moved.

Figure 2 is a block diagram showing the configuration of the lens anti-vibration device of the optical pickup according to an embodiment of the present invention.

3 is a block diagram illustrating an example of a tracking error detection unit illustrated in FIG. 2.

4 is a block diagram illustrating another example of the tracking error detection unit illustrated in FIG. 2.

FIG. 5 is a signal waveform diagram illustrating a tracking error signal and an offset voltage according to a moving position of a lens in FIG. 4. FIG.

<Simple explanation of symbols for main parts of drawings>

10, 20: optical pickup 12: tracking actuator

14 lens 22 tracking error detection unit

24, 30: switch 26: tracking filter

28: offset detection unit 32: tracking actuator drive unit

34: microcomputer 33, 35: adder

36, 38: phase delay 40: phase comparator

42, 48: low pass filter (LPF) 44: optical disc

46: differential amplifier

In order to achieve the above object, the vibration preventing device of the optical pickup lens according to the present invention includes a pickup means for reading information from a disc, a tracking error detection means for detecting a tracking error signal from an output signal of the pickup means, and a search mode. And a microcomputer for generating a control signal corresponding to a recording / reproducing mode, offset detection means for detecting an offset voltage proportional to the degree of lens deflection in the tracking error signal input from the tracking error detecting means in the search mode; In the search mode, a tracking actuator driving means for controlling the tracking actuator for driving the lens to compensate for the offset voltage is characterized in that it is provided.

Other objects and advantages of the present invention in addition to the above object will become apparent from the description of the preferred embodiment of the present invention with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 2 to 5.

FIG. 2 is a block diagram illustrating a structure of an anti-vibration device for an optical pickup lens according to an exemplary embodiment of the present invention, wherein the lens anti-vibration device of FIG. An optical pickup 20 for converting and outputting an ordinary signal, a tracking error detector 22 for detecting a tracking error signal Te from an output signal of the optical pickup 20, and a tracking error detector 22 according to a control signal And a first switch 22 for connecting the tracking filter 26 or the offset detector 28 and a tracking error signal Te input through the first switch 22 to track the tracking control signal. An offset detector 28 for detecting the offset signal by filtering the tracking error signal Te input through the filter 26 and the first switch 22, and the tracking filter 26 or offset detector according to the control signal. 28 and the tracking actuator driver 32 The tracking actuator driver 32 for driving the tracking actuator in accordance with the second control switch 30, the tracking control signal input through the second switch 30, and the microcomputer 34 generating a control signal according to the operation mode. ).

In the lens anti-vibration apparatus shown in FIG. 2, the optical pickup 20 detects an amount of reflected light by irradiating a light beam onto an optical disc (not shown) and converts it into an electrical signal. The tracking error detector 22 detects the tracking error signal Te from the output signal of the optical pickup 20. The first switch 24 connects the tracking error detector 22 and the tracking filter 26 or the offset detector 28 according to the control signal input from the microcomputer 34. Specifically, when the microcomputer 34 applies a control signal indicating a normal recording / reproducing mode, the first switch 24 connects the tracking error detection unit 22 and the tracking filter 26. On the other hand, when the microcomputer 34 applies a control signal indicating the search mode, the first switch 24 connects the tracking error detector 22 and the offset detector 28. The tracking filter 26 compensates the gain and phase of the tracking error signal Te input from the tracking error detection unit 22 via the first switch 24 in the normal recording / reproducing mode for tracking control. Will generate a signal. The offset detector 28 detects the offset signal by low-pass filtering the tracking error signal input from the tracking error detector 22 via the first switch 24 in the search mode. The second switch 30 connects the tracking filter 26 or the offset detector 28 and the tracking actuator driver 32 according to the control signal input from the microcomputer 34. Specifically, when the microcomputer 34 applies a control signal indicating a normal recording / reproducing mode, the second switch 30 connects the tracking filter 26 and the tracking actuator driver 32. On the other hand, when the microcomputer 34 applies the control signal indicating the search mode, the second switch 30 connects the offset detector 28 and the tracking actuator driver 32. The tracking actuator driver 32 is a tracking actuator (not shown) mounted to the optical pickup 20 in accordance with a tracking control signal input from the tracking filter 26 via the second switch 30 in the normal recording / reproducing mode. Adjust the current signal or the voltage signal so that the lens follows the track. In addition, in the search mode, the tracking actuator driver 32 adjusts a current signal or a voltage signal supplied to the tracking actuator according to an offset signal input from the offset detector 28 via the second switch 30 so that the lens is optically lighted. Position it in the center of the pickup. The microcomputer 34 controls the operations of the first and second switches 24 and 30 by generating a control signal in accordance with the operation mode of the optical recording / reproducing apparatus, that is, the normal recording / reproducing mode or the search mode.

FIG. 3 is a block diagram illustrating an example of the tracking error detection unit 22 shown in FIG. 2, and the tracking error detection unit 22 illustrated in FIG. 3 is referred to as differential phase detection (hereinafter referred to as DPD). The tracking error signal Te is detected using the method. The tracking error detection unit 22 of the DPD method shown in FIG. 3 is connected to the quadrant photodetector PD of the optical pickup 20 to generate the first and second sum signals Ia + Ic and Ib + Id. A first phase delay unit for delaying the phases of the first sum signal Ia + Ic output from the first adder 33 under the control of the first and second adders 33 and 35 and the microcomputer 34; (36), a second phase delay unit (38) for delaying the phase of the second sum signal (Ib + Id) output from the second adder (35) under the control of the microcomputer (34); Low phase filtering for comparing the phases of the signals output from the second phase delay units 36 and 38 and output signals of the phase comparator 40 to detect the tracking error signal Te. A pass filter (LPF) 42 is provided.

In general, the DPD method detects a tracking error signal by comparing the phase of the photodetection signal detected by the photodetector. In this case, when the lens is out of the center of the optical pickup, the tracking error signal moves the reflected beam received by the photodetector on the photodetector, and includes a DC offset voltage proportional to its magnitude. Accordingly, in the normal recording / reproducing mode, the DC offset generated in the tracking error signal must be corrected in order to perform tracking control. In other words, since the offset voltage shifts the position of the tracking and the beam, in the normal recording / reproducing mode, the microcomputer 34 detects the offset voltage from the tracking error signal Te so that the offset voltage can be compensated. And phases of the second phase delay units 36 and 38. On the other hand, in the search mode, the microcomputer 34 controls the first and second phase delay units 36 and 38 to force misalignment of phases. As a result, the tracking error signal Te includes an offset voltage proportional to a position where the lens is out of the center of the pickup.

In detail, the four-segment photodetector PD in FIG. 3 is mounted in the optical pickup 20 shown in FIG. It is composed of divided photodetection pieces PDa, PDb, PDc, and PDd. Each of the photodetectors PDa, PDb, PDc, and PDd converts the amount of light received into an electrical signal to generate first to fourth photodetection signals Ia, Ib, Ic, and Id that are proportional to the amount of reflected light. do. The first adder 33 generates the first sum signal Ia + Ic by adding the first and third photodetection signals Ia and Ic output from the photodetection pieces PDa and PDc in the left diagonal direction. . The second adder 35 generates the second sum signal Ib + Id by adding the second and fourth photodetection signals Ib and Id output from the photodetection pieces PDb and PDd in the right diagonal direction. . The first phase delay unit 36 delays and outputs the phase of the first sum signal Ia + Ic by a predetermined time under the control of the microcomputer 34, and the second phase delay unit 38 also outputs the microcomputer 34. The second sum signal Ib + Id is delayed for a predetermined time and then output. In detail, when the microcomputer 34 applies a control signal indicating a normal recording / reproducing mode, the first and second phase delay units 36 and 38 compensate for offset components included in the tracking error signal Te. This will delay the phase. On the other hand, when the microcomputer 34 applies the control signal indicating the search mode, the first and second phase delay units 36 and 38 cause the offset component according to the position of the lens to be included in the tracking error signal Te. This will delay the phase. The phase comparator 40 generates a phase difference signal by comparing phases of the signals output from the first and second phase comparators 36 and 38. The low pass filter 42 generates a tracking error signal Te by low pass filtering the phase difference signal output from the phase comparator 40. In the search mode, since the tracking error signal Te includes an offset voltage proportional to a position where the lens is out of the center of the pickup, an offset included in the tracking error signal Te in the offset detector 28 shown in FIG. 2. By detecting the voltage and compensating the offset voltage in the tracking actuator driver 32, it is possible to control the lens to be positioned at the center of the optical pickup 20.

In this case, the tracking error signal Te output from the low pass filter 42 includes a reflection beam received by the photodetector PD when the lens 14 is out of the center of the optical pickup 20. The phase shift is to include a DC offset voltage proportional to its magnitude.

FIG. 4 is a block diagram illustrating another example of the tracking error detection unit 22 shown in FIG. 2, and the tracking error detection unit 22 shown in FIG. 4 uses a push-full tracking method. The error signal Te is detected. The push-pull tracking error detector 22 shown in FIG. 4 low pass the differential amplifier 46 and the output signal of the differential amplifier 46 connected to the photodetector PD ′ of the optical pickup 20. And a low pass filter 48 for filtering to detect the tracking error signal Te.

In FIG. 4, the photodetector PD is composed of photodetectors PDa, PDb, PDc, PDd divided into four in the track and radial direction as shown in FIG. Each of the photodetectors PDa, PDb, PDc, and PDd converts the amount of light received into an electrical signal to generate first to fourth photodetection signals Ia, Ib, Ic, and Id that are proportional to the amount of reflected light. do. First input terminals of the first and second photodetection signals Ia and Ib output from the left photodetection pieces PDa and PDb to the one side input terminal of the differential amplifier 46 of the tracking error detection unit 22 based on the track direction. The sum signal Ia + Ib is input. In addition, the second sum signal Ic of the third and fourth photodetection signals Ic and Id output from the right side photodetection pieces PDc and PDd to the other input terminal of the differential amplifier 46 based on the track direction. + Id) is inputted. The differential amplifier 46 differentially outputs the first and second sum signals Ia + Ib and Ic + Id input to the two input terminals. The low pass filter 48 detects the tracking error signal Te by low pass filtering the differential amplification signal output from the differential amplifier 46. In this case, the tracking error signal Te includes an offset voltage proportional to the position where the lens is out of the center of the pickup. Accordingly, in the search mode, the offset detector 28 illustrated in FIG. 2 detects the offset voltage included in the tracking error signal Te and compensates the offset voltage in the tracking actuator driver 32 to compensate for the offset voltage of the optical pickup 20. It can be controlled to be located in the center of the. On the other hand, in the normal recording / reproducing mode, tracking control can be performed by correcting the offset voltage included in the tracking error signal using a general dual push-pull method.

FIG. 5 illustrates offset voltages detected by the tracking error signal Te according to each position of the lens by the offset detection unit 28 shown in FIG. 2.

When the lens is positioned at the center of the optical pickup 20 in the search mode, the tracking error signal Te detected by the tracking error detector 22 has a center voltage of '0' as shown in (A). The tracking error signal Te is input to the offset detector 28 and low-pass filtered to detect an offset signal having a value of '0'. On the other hand, when the lens is out of the center of the optical pickup 20, the tracking error signal Te includes a DC offset component as shown in (B) and (C). Since the tracking error signal Te is low-pass filtered by the offset detector 28, an offset signal having '+' and '-' values, respectively, is detected. Here, it can be seen that the offset signal detected by the offset detector 28 has a value proportional to the position where the lens is out of the center of the pickup. Accordingly, the tracking actuator driver 32 controls the tracking actuator so that the offset voltage is '0' so that the lens is positioned at the center of the pickup and vibration does not occur even after the search is completed. Since there is no vibration of the lens even after the search, the tracking servo can be stabilized in a short time, thereby reducing the access time.

As described above, in the optical pickup lens vibration preventing device according to the present invention, when the optical recording / reproducing apparatus is in the search mode, the lens is positioned at the center of the optical pickup by detecting and compensating for an offset voltage proportional to the degree of deflection of the lens. Can be controlled. Accordingly, the vibration due to the bias of the lens is prevented, so that not only the tracking servo after the search can be stabilized in a short time but also the access time can be shortened.

Incidentally, although the present invention has been described with reference to only an optical recording / reproducing apparatus using an optical head, those skilled in the art will appreciate that the present invention can be applied to a recording / reproducing apparatus using a magnetic head or the like.

In other words, those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (6)

Pickup means for reading information from the disc; Tracking error detecting means for detecting a tracking error signal from an output signal of the pickup means; A microcomputer for generating control signals corresponding to a search mode and a recording / playback mode; Offset detection means for detecting an offset voltage proportional to the degree of lens deflection in the tracking error signal input from the tracking error detection means in the search mode; And a tracking actuator driving means for controlling the tracking actuator for driving the lens to compensate for the offset voltage in the search mode. The method of claim 1, Tracking filter means for filtering the tracking error signal input from the tracking error detection means in the recording / reproducing mode and supplying the tracking error driving means to the tracking actuator driving means; A first switch for selectively connecting said tracking error detection means to said offset detection means or tracking filter means in accordance with a control signal of said microcomputer; And a second switch for selectively connecting said offset detecting means or tracking filter means to said tracking actuator driving means in accordance with a control signal of said microcomputer. The method of claim 1, The tracking error detection means First and second addition means for calculating a plurality of photodetection signals detected by a multi-segment photodetector mounted in the optical pickup to generate first and second sum signals in a diagonal direction, respectively; First and second phase delay means for delaying phases of the first and second sum signals, respectively, according to the control of the microcomputer; Phase comparing means for comparing a phase of a signal output from each of said first and second phase delay means to generate a differential phase signal; And low pass filtering means for low pass filtering the differential phase signal to generate the tracking error signal. The method of claim 3, wherein The microcomputer And inputting the tracking error signal to control the first and second phase delay means to include the offset voltage in the tracking error signal in the search mode. The method of claim 3, wherein The microcomputer And the first and second phase delay means are configured to compensate the offset voltage included in the tracking error signal in the recording / reproducing mode by inputting the tracking error signal. The method of claim 1, The tracking error detection means First and second addition means for calculating a plurality of photodetection signals detected by a multi-segment photodetector mounted to the optical pickup to generate first and second sum signals in a track direction, respectively; Differential amplifying means for differentially amplifying the first and second sum signals to generate a differential amplifying signal; And low pass filtering means for low pass filtering the differential amplified signal to generate the tracking error signal.