KR100273760B1 - Defect Compensation Device and Method of Optical Disc Drive - Google Patents

Abstract

PURPOSE: A method and a device for compensating a defect of an optical disk drive, are provided to easily perform signal compensation for a defect on a disk in servo control of the optical disk drive. And the method and the device enable signal compensation by a large or continuous defect on the disk in the servo control. CONSTITUTION: When supplying a reproducing signal read from an optical disk(1) to a servo control loop, a DFCT(Defect detecting signal) is enabled in a block where a reproducing signal by a defect is detected, to make the servo control loop perform a defect compensation operation. A control signal output unit receives the DFCT, to output a control signal for the defect compensation operation in the block where the DFCT is enabled. A reference voltage supply unit supplies a preset reference voltage to the servo control loop correspondingly to an average voltage level of the reproducing signal by the control signal.

Description

Defect Compensation Device and Method of Optical Disc Drive

The present invention relates to an optical disc drive for recording data in an information recording disc such as an optical disc and reproducing the recorded data, and more particularly, to an apparatus and method for processing a defect of an optical disc.

In the optical recording and reproducing technique of recording and reproducing information on an optical disc (hereinafter referred to as a disc) by using a laser, information is read as an amount of change of laser beam reflected light with respect to the optical disc. The method of recording data on an optical disc by changing reflected light includes a method of forming a concave pit on a disc substrate to use interference between the pit and a reference plane, a method of changing the polarization direction of a magneto-optical recording medium such as a magneto-optical disc, and To use the difference in the amount of reflected light depending on the crystallizing state of the recording material, such as phase-change discs (CD-RW: CD-ReWritable), and to modify organic pigments, such as CD-R (CD-Recordable). And the like. Among them, a method capable of repeating recording and reproducing, especially a phase change type method, is widely applied to a compact disc (CD) or a digital video disc or a digital versatile disc (DVD).

In the optical disc drive, optical pick-up is used to read data recorded on the optical disc in the above-described manner, or to record data. In the process of reading the data recorded on the disc by the optical pickup, abnormal signals may be detected by the defect such as scratches on the disc, except for normal data reproduction signals. In the data reproducing loop, the error is corrected by an error correction code or the like, and the defect generated when the data related to the servo information is detected is compensated in the servo loop. Hereinafter, the compensation of the defect caused when the data related to the servo information is detected will be described with reference to the accompanying drawings.

FIG. 1 is a schematic block diagram of a related part in a tracking servo among defect processing related parts of a general optical disk drive, and FIG. 2 is a waveform diagram of each input and output signal of FIG. It didn't work. FIG. 1 illustrates a tracking servo as an example of various servo loops configured in an optical disk drive for convenience of explanation, and another servo loop has a similar decomp compensation configuration.

The optical pickup 10 first reads data from the disk and applies this data reproduction signal to a radio frequency amplifier (RF AMP) 39. As shown in FIG. 2, the reproduction signal is in the form of an eye pattern when it is a normal signal, and when there is a defect on the disc, an abnormal signal is generated accordingly. The high frequency amplifier 39 amplifies the reproduction signal and applies the amplified signal to a recording / reproducing data processing unit (not shown) for detecting data, and transmits signals related to various servos in each of the servo loops (not shown). Is not applied). A tracking servo loop among these servo loops is shown in FIG. 1. The tracking controller 25 receives a tracking error signal (TE) from the high frequency amplifier 39 and outputs a tracking output signal (TO) to the tracking coil.

In more detail, in general, an optical disc drive includes a plurality of servo circuits in a basic operation for reproducing data recorded on an optical disc. Such servos include a tracking servo, a focus servo, a rotation servo, and an optical transmission servo. There may be.

The tracking servo is a servo that allows the optical pickup 10 to follow a concentric or spiral track centerline, which is a data recording form of the optical disk, and the focus servo is a lens in which the focus of the laser beam of the optical pickup 10 coincides with the optical disk surface. Servo to maintain the distance between the optical disk and the surface of the optical disk. The rotation (normally CLV: Constant Linear Velocity) servo is a servo for controlling the speed at which the optical disk rotates at a constant speed (or right angle). Refers to a servo for the optical pickup 10 to slide on the optical disk surface to move to a desired track.

For example, the servo may be executed by using a focus error signal in the case of a focus servo and a tracking error (TE) signal in the case of a tracking servo. It applies to the servo loop (FIG. 1 and FIG. 2 show only an example of a tracking servo for convenience of description). In this case, the tracking error signal TE as shown in FIG. 2 shows an abnormal waveform in the defect portion of the reproduction signal, and when the tracking controller 25 performs the tracking servo according to the signal of the defect portion of the tracking error signal TE. Serious errors such as track jumps can occur. Accordingly, when the high-definition amplifier 39 detects a defect, the high-definition amplifier 39 applies a DeFeCT detecting signal (DFCT) as shown in FIG. 2 to the servo unit 41, and the servo unit 41 enables the defect detection signal. In the period of), the tracking error signal TE is held or the gain of the signal is lowered. Therefore, the servo control signal for the tracking servo of the tracking control unit 25, that is, the tracking output signal TO as shown in FIG. 2 appears as a waveform based on the tracking error signal TE in the absence of the defect, and then enables the defect detection signal DFCT. In the section, the tracking error signal TE is shown to be held. Therefore, the tracking control unit 25 can prevent the malfunction due to the defect to a certain extent, although the defect portion cannot perform the tracking servo by the tracking error information originally recorded on the disc.

However, the above-described decomp compensation method should include a signal hold circuit in a servo control unit such as a tracking control unit, and in the case of a large defect such as a scratch of a disc or a continuous hold, the hold timing becomes long, and accordingly control of the tracking servo is performed. Anxiety could cause malfunction such as track jumping. In addition, there is a limit to the signal level in reducing the gain of the signal during the period in which the defect detection signal is enabled in the servo control unit such as the tracking control unit.

Accordingly, an object of the present invention is to provide a defect compensation apparatus and method which can easily compensate for a defect on a disc in servo control of an optical disc drive.

Another object of the present invention is to provide a defect compensation device capable of compensating for a defect on a disc in servo control of an optical disc drive with a simple configuration.

It is another object of the present invention to provide a defect compensation apparatus and method that can easily compensate for a signal due to a large or continuous defect on a disc in servo control of an optical disc drive.

In order to achieve the above object, the present invention amplifies a playback signal read from a disk during servo control of an optical disk drive, and applies a playback signal for each servo control to a servo control loop for each servo control, and defects the disk. In the defect compensation method of enabling a defect detection signal when a reproduction signal is generated, the reproduction signal for the servo control instead of the reproduction signal for the servo control with the servo control loop when the defect detection signal is enabled. Characterized in that the predetermined level of the signal is applied to the average voltage level of.

1 is a schematic block diagram of a related part in a tracking servo among defect processing related parts of a general optical disc drive.

2 is a waveform diagram of each input and output signal of FIG. 1.

3 is a schematic overall block diagram of an optical disk drive to which the present invention is applied;

4 is a schematic block diagram of a related part of a tracking servo among the related parts of a defect processing of an optical disc drive according to an embodiment of the present invention;

5 is a waveform diagram of each input and output signal of FIG. 4.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, specific matters such as specific building blocks are shown, which are provided to help a more general understanding of the present invention, and the specific matters may be changed or changed within the scope of the present invention. It is self-evident to those of ordinary knowledge in Esau.

3 is a block diagram illustrating an example of an optical disk drive to which the present invention is applied, and illustrates a drive capable of repeatedly recording and reproducing data. Referring to FIG. 3, the optical disc drive records information on the optical disc 1 or reproduces the recorded information by the optical pickup 10. The optical pickup 10 is supported by the linear motor 20 and is movable to the inside and the outside of the optical disc 1.

The optical pickup 10 includes a semiconductor laser oscillator 13, various lenses, a half prism 17, a tracking coil 11a, a focus coil 11b, and the like. When recording data, the laser oscillator 13 outputs a laser beam of the data recording level, and the laser beam is scanned to the position to record the optical disk 1 via the half prism 17 and the lens. When data is reproduced, the laser oscillator 13 outputs a laser beam of a data reproduction level, and the laser beam is reflected at the data reproduction position of the optical disc 1 and input to the photodetector 15 via the half prism 17. The laser oscillator 13 is controlled by the laser controller 21 to control the level of the output laser beam and the output on / off interval. The laser controller 21 controls the laser oscillator 13 according to, for example, 2-7 modulation obtained by the modulator 22, and the modulator 22 records the recording data applied by the error correction part 35 (to be described later) when data is recorded. A signal suitable for the conversion, for example, 2-7 modulated data is converted. The laser control section 21 and the modulation section 22 operate in synchronization with a recording clock signal applied from a PLL or the like in the recording / reproducing data processing section 40 (to be described later). The photodetector 15 generates an electrical reproduction signal according to the amount of light of the laser beam reflected from the optical disk 1 and applies the signal to the high frequency amplifier 31. The high frequency amplifier 31 amplifies the reproduced signal and focuses it on the focus control unit 23 and the tracking control unit 25. To the linear motor control unit 27, the spindle motor control unit 29, and the recording / reproducing data processing unit 40.

The focus control unit 23 detects the degree of focus of the laser beam from the applied reproduction signal, and applies an operating power to the focus coil 11b to control the laser beam focus of the optical pickup 10 to adjust the focus normally. The tracking controller 25 detects a tracking error signal from the applied reproduction signal, applies an operating power to the tracking coil 11a for the normal tracking operation, and checks the rotational speed of the optical disc 1 from the reproduction signal. Apply the control signal accordingly. The linear motor controller 27 controls the linear motor 20 by detecting the moving speed of the optical pickup 10. On the other hand, a D / A (Digital to Analog) converter 33 is provided for exchanging information between the focus control unit 23, the tracking control unit 25, the linear motor control unit 27, and the central processing unit (CPU) 30 which controls the overall control of the optical disk device. The spindle motor controller 29 controls the spindle motor 3 to control the optical disk 1 to rotate at a constant linear velocity (CLV).

The recording / reproducing data processing unit 40 reproduces the recorded data by receiving the reproduction signal, applies the reproduced data to the error correction unit 35, or performs a process for recording the data. The error correction unit 35 corrects an error by referring to an ECC code or the like among the reproduction data, or adds an ECC code to the memory 31 to be recorded from an external device such as a host through the interface unit 37 and transmits it to the memory 31. The data transferred to the memory 31 is temporarily stored and sequentially applied to the modulator 22 to be recorded on the optical disc 1. The memory 31 also stores the overall operating program of the CPU 30. The CPU 30 controls the overall operation of the optical disk device, and in particular, controls to search or track the correct position for recording or reading information on the disk.

According to the present invention, the optical disc drive amplifies the reproduction signal read out from the optical disc 1 and applies a reproduction signal for each servo control to the respective servo control units. When enabling the detection signal, in accordance with a feature of the present invention, a signal having a predetermined level is applied to the servo control loop instead of a reproduction signal for the servo control, with an average voltage level of the reproduction signal for the servo control. It will be described in more detail with reference to the drawings.

FIG. 4 is a schematic block diagram of a related part of a tracking servo among defect processing related parts of an optical disc drive according to an exemplary embodiment of the present invention, and FIG. 5 is a waveform diagram of each input and output signal of FIG. 4. As shown in FIG. 4 and FIG. 5, a case where the present invention is applied to a tracking servo will be described as an example.

4 and 5, when the reproduction signal from the optical pickup 10 is applied to the high frequency amplifier 39, the high frequency amplifier 39 amplifies the tracking error signal TE and the defect detection signal DFCT when there is a defect. Output in the same manner as in the prior art. However, at this time, the defect detection signal DFCT is not applied to the tracking control unit 25 unlike the conventional art, and is applied to the defect compensation compensator 50 according to the feature of the present invention.

When the applied defect detection signal DFCT is enabled, the defect compensation compensator 50 applies the reference voltage Vref of the average voltage level of the tracking error signal TE to the tracking controller 25. The reference voltage Vref is connected to the emitter stage. A reference voltage consisting of a transistor TR1 connected to a resistor R1 is connected to the base terminal between the output terminal of the tracking error signal TE of the high frequency amplifier 39 and the input terminal of the tracking error signal TE of the tracking controller 25. And a control signal output section 57 for applying turn-on power to the transistor TR1 through the resistor R1 when the defect detection signal DFCT is enabled.

When the transistor TR1 is turned on, the tracking error signal TE1 input to the tracking controller 25 becomes equal to the level of the reference voltage Vref as shown in FIG. 5.

As described above, when the defect detection signal DFCT is applied to the control signal output unit 57 and the control signal output unit 57 applies the driving voltage of the transistor TR1 through the resistor R1 when the defect detection signal DFCT is enabled, this operation is performed. In the example as shown in FIG. 5, since the defect detection signal DFCT is enabled when the low state is low, the control signal output unit 57 receives the defect detection signal DFCT as an inverter 53 and the inverter 53. It is possible to configure the output of to be applied to R1.

However, in an embodiment of the present invention, a multiplexer 55 is further configured to prevent malfunction of the transistor TR1 due to noise, and the AND gate 51 is another for temporarily erasing the tracking error signal TE. It is configured to receive the control signal. One input terminal of the multiplexer 55 receives the output of the inverter 53, and the type force terminal is connected to the ground terminal GND. The select terminal of the multiplexer 55 is connected to the inverter 53 input terminal.

When the enabled state of the defect detection signal DFCT, that is, the low state is input to one input terminal of the AND gate 51, the output of the AND gate 53 goes low as shown in FIG. 5, and the output of the inverter 53 is HIGH. ) State. At this time, the selector of the multiplexer 55 is set to a low ("0") state. In this case, the multiplexer 55 is preset to select the output of the AND gate 53. Therefore, the output of the multiplexer 55 goes high as shown in FIG. 5, and eventually the transistor TR1 is turned on.

The AND gate 51 is configured to cancel the tracking error signal TE by receiving a control signal other than the Defect detection signal, which is high when the control signal is not normally enabled, and indicates movement between tracks applied by the CPU 30. There may be a track jump signal JUMP for a track jump.

On the other hand, when another control signal such as the track jump signal JUMP is not enabled and the non-enable state of the defect detection signal DFCT, that is, the high state is input to one input terminal of the AND gate 51, the output of the AND gate 53 is output. Is high and the output of inverter 53 is low. At this time, the selector of the multiplexer 55 is high ("1"), in which case the multiplexer 55 selects the ground terminal GND, so the output of the multiplexer 55 is low, so that the transistor TR1 is turned off. Keep it.

Defect compensation by the configuration and method as described above is compensated before the cracking error signal TE is applied to the tracking control unit 25, according to the design of the circuit can be decompensation only by the configuration of the defect compensation unit 50 according to the present invention, FIG. The defect error signal DFCT as shown in FIG. 5 may also be applied to the tracking control unit 25, such that the decompensation unit 50 according to the present invention may be added to the conventional defect compensation loop.

Meanwhile, in the above-described embodiment of the present invention, the present invention is implemented as a tracking servo as an example, but the present invention may be implemented in a focus servo.

As described above, the present invention amplifies the playback signal read from the disk during the servo control of the optical disk drive, and applies the playback signal for each servo control to the servo control loop for each servo control, In the defect compensation method of enabling a defect detection signal when a reproduction signal is generated, when the defect detection signal is enabled, the servo control loop replaces the reproduction signal for the servo control with the servo control loop instead of the reproduction signal for the servo control. Since the signal of the preset level is applied as the average voltage level, it is easy and simple to compensate for the defect on the disc in the servo control of the optical disc drive, and also to compensate the signal by the large or continuous defect on the disc. There are advantages to it.

Claims (9)

In the defect compensation method of an optical disc drive, when a reproduction signal read out from an optical disc is applied to each servo control loop, the defect detection signal is enabled in a section in which a reproduction signal by the defect is detected. Presetting a reference voltage corresponding to the average voltage level of the reproduction signal; And applying the reference voltage to each of the servo control loops instead of the regeneration signal in a section in which the defect detection signal is enabled. The method of claim 1, wherein the servo is a tracking servo and a focus servo. When the reproduction signal read out from the optical disc is applied to the servo control loop, the defect detection signal is enabled in the section in which the reproduction signal by the defect is detected so that the servo control loop performs the defect compensation operation. In A control signal output unit configured to receive the defect detection signal and output a control signal for the defect compensation operation in a section in which the defect detection signal is enabled; And a reference voltage applying unit configured to apply, to the servo control loop, a preset reference voltage corresponding to the average voltage level of the reproduction signal by the control signal. The defect compensation device of claim 3, wherein the servo is a tracking servo and a focus servo. The method of claim 3, And the control signal output unit further receives a predetermined control signal other than the defect detection signal and outputs the predetermined control signal to the reference voltage applying unit. The method of claim 5, And said predetermined other control signal comprises a track jump signal for movement between tracks of said optical disk applied by a central processing unit for controlling the overall operation of said optical disk drive. When the reproduction signal read out from the optical disc is applied to the servo control loop, the defect detection signal is enabled in the section in which the reproduction signal by the defect is detected so that the servo control loop performs the defect compensation operation. In A control signal output unit receiving the defect detection signal and predetermined control signals and outputting a first control signal for the defect compensation operation; And a reference voltage applying unit configured to apply, to the servo control loop, a predetermined reference voltage corresponding to the average voltage level of the reproduction signal by the first control signal. The defect compensation apparatus of claim 7, wherein the servo is a tracking servo and a focus servo. The method of claim 7, wherein And the predetermined control signals include a track jump signal representing movement between tracks of the optical disk applied by a central processing unit controlling overall operations of the optical disk drive.

Images