KR20040022096A - A method for securing a tracking error signal in a compact disc player - Google Patents

Abstract

PURPOSE: A method for stabilizing a tracking error signal of a compact disc player is provided to prevent a servo from becoming unstable due to a sound pressure or a large scratch. CONSTITUTION: A servo unit judges whether a micro-controller unit transmits a search command when an RF part of a compact disc player executes the first and second bottom holds(S11). When the search command is not transmitted, it is judged whether a defect is detected or not(S13). When the defect is detected, the servo is muted-on(S15), and a tracking error inverted signal and an existing tracking error signal are summed up to each other to cancel the two signals(S16). The micro-controller unit judges whether the defect detection is completed(S18). When the defect detection is completed, the servo is turned on(S19). When the defect detection is not completed, the servo is maintained in the mute-on state and the sum of the tracking error inverted signal and the tracking error signal is maintained(S20).

Description

A method for securing a tracking error signal in a compact disc player}

The present invention relates to a method for stabilizing a tracking error signal of a compact disc player. More particularly, when a defect is detected on an optical disc, an inverted signal having a gain equal to a tracking error signal is added. The present invention relates to a tracking error signal stabilization method of a compact disc player that cancels the amount of excitation due to defect generation in combination with a signal.

In general, in a device that processes data using an optical pick-up such as a CD, DVD, CD-RW drive, and the like, the seek time for the device to read data is determined by the transfer device and the optical pickup. It is greatly affected by the algorithm performance related to Servo. Here, the transfer apparatus transfers the optical pickup for performing an operation of reading or writing data to a desired target position on the optical disc.

1 is a block diagram schematically showing the internal structure of a typical compact disc player. Referring to FIG. 1, a typical compact disc player includes: an optical pickup 20 for reading recorded data on an optical disc 10; An RF unit 30 for shaping the signal detected by the optical pickup 20 and outputting it as a binary signal; A digital signal processor (DSP) for restoring the binary signal to original data with its own clock synchronized with the binary signal; A servo unit 60 for controlling a focusing correction operation and a tracking correction operation of the optical pickup 20 based on a focusing error (FE) signal and a tracking error (TE) signal generated and output from the optical pickup 20; A drive driver 30 for horizontally moving the optical pickup 20 through a sled motor 21 and applying a driving force to rotationally drive the optical disc through a spindle motor 22; A DRAM (90) for storing the digitally processed data; And a microcontroller unit (MCU) 70 for controlling the reproduction process of the optical disc 10 and the signal flow between the components.

The microcontroller unit 70 responds to a control command signal provided by a microcomputer and a servo control signal output from the optical pickup 20, that is, an address information signal regarding a position and a control signal provided by the digital signal processor 50. Done. In addition, the servo unit 60 consisting of a focus servo, a tracking servo, and a rotation servo provides a drive signal to the spindle motor and the optical pickup 20. The spindle motor rotates at the normal speed by the driving signals, and the optical pickup 20 focuses on the surface of the optical disc 10 to detect the amount of light reflected from the reflecting surface of the optical disc 10 to perform data pickup. The picked-up data is shaped into a digital signal by the RF unit 40, and then the digital signal processor 50 detects a sub-code to the servo unit 60 as an optical pickup 20. A control signal is generated to allow the user to return to a position where an error due to a skip is generated. The control signal is corrected to decompress the pickup data through decoding, and separates the video or audio signal to output. Done.

On the other hand, if there is a defect on the optical disc, the wrong signal is read due to the defect, and thus data cannot be restored correctly. Accordingly, the optical disc reproducing apparatus employs a disc defect detecting circuit for monitoring the defect and its length in order to recover data in consideration of the defect on the disc.

In a typical disc defect detection circuit, the optical pickup optically picks up the information recorded on the disc and outputs electrical signals by light detection. The RF summing circuit sums this and outputs an RF signal. The first peak hold circuit detects the peak level of the RF signal while rapidly following the level change. A constant voltage level shifter shifts the output of the first peak hold circuit by a certain level. The second peak hold circuit detects the peak level of the RF signal while slowly following the level change. Thereafter, the comparator compares the output of the constant voltage level shifter and the output of the second peak hold circuit to generate a defect monitor signal DFCT indicating whether the disk is defective. At this time, when there is a defect on the disc, the defect monitor signal DFCT is output as a pulse having a width corresponding to the length of the scratch.

Therefore, since the RF bottom signal is used as the RC time constant when the defect is detected among the servo functions, the defect effect remains during the time constant charging and discharging.

FIG. 2 is a diagram schematically illustrating a problem of detecting a tracking error signal of a compact disc player according to the related art, and is a description of an optical beam pickup with an E beam and an F beam and a tracking error signal. The relationship is shown.

Specifically, when the optical disk rotates along the rotational direction, the E beam and the F beam of the optical pickup 20 proceed from, for example, a) to c), and eventually the E on the pit of the optical disk as in c). When both the beam and the F beam exist on the defect area, the defect is detected. At this time, as shown in the right side of FIG. 2, as the time progresses, the tracking error signal initially lifts only a little as in a), but a disturbance is applied to the tracking error (TE) signal before the defect detection as in A. Both the E beam and the F beam are placed on the defect area, and the tracking error (TE) signal is changed to a servo mute like B after the defect detection.

FIG. 3 is a diagram illustrating a conventional operation flow at the time of detecting a defect. When the first bottom hold and the second bottom hold are performed from the RF unit 40 of FIG. 1 (S01), the servo unit ( 60 determines whether the defect is detected (S02), and if the defect is detected, mutes the servo on (S03), and turns on the servo if the defect is not detected. ) (S04).

Therefore, in the case of a CDP for a cassette, when there is a sound pressure or a large scratch on the surface of the CDP, such a defect is detected, and a skipping phenomenon occurs thereby degrading the performance of the compact disc player. have.

An object of the present invention for solving the above problems is to provide a tracking error signal stabilization method of a compact disc player which prevents the servo from becoming unstable by sound pressure or large scratches.

1 is a block diagram schematically showing the internal structure of a conventional compact disc player.

2 is a diagram schematically illustrating a problem of detecting a tracking error signal of a compact disc player according to the related art.

3 is a view showing an operation flow in the conventional defect detection.

4 is an operation flowchart showing a tracking error signal stabilization method of a compact disc player according to the present invention.

<Description of Symbols for Major Parts of Drawings>

10: compact disc (CD) 20: optical pickup

30: drive driver 40: RF unit

50: digital signal processor (DSP) 60: servo unit

70: microcontroller unit (MCU) 80: digital-to-analog converter (DAC)

90: dynamic RAM

As a means for achieving the above object, the tracking error signal stabilization method of the compact disc player according to the present invention, i) a microcontroller unit if the RF unit of the compact disc player performs the first and second bottom hold (Bottom Hold); Determining, by the servo unit, whether a search command has been transmitted from the controller; Ii) determining whether a defect is detected when the search command is not transmitted; Iii) muting the servo if the defect is detected; And iii) canceling the sum of the tracking error inversion signal and the original tracking error signal when the defect is detected.

In addition, the present invention includes the steps of: i) the microcontroller unit determines that the defect detection is complete; Iii) turning on the servo when the determination is complete; And iv) if the determination is not completed, maintaining the sum of the tracking error inversion signal and the existing tracking error signal while maintaining the servo mute on state.

Here, the tracking error inversion signal has the same gain as the tracking error signal, and is added to each other with the original tracking error signal to cancel the amount of excitation during detection of the defect.

In addition, in the tracking error signal stabilization method of the compact disc player according to the present invention, i) if the RF unit of the compact disc player executes the first and second bottom hold, the servo unit may determine whether a search command is transmitted from the microcontroller unit. Determining; Ii) if the search command is transmitted, performing the existing search process in the same manner; Iii) determining whether a defect is detected if the search command is not transmitted; Iii) keeping the servo on if the defect is not detected; Iii) muting the servo if the defect is detected; Iii) adding the tracking error inversion signal and the original tracking error signal if the defect is detected; Iv) checking whether the microcontroller unit has been completed when the defect detection is completed, and turning on the servo unit when the determination is completed; And iii) if the microcontroller unit has not completed the determination, maintaining the sum of the tracking error inversion signal and the original tracking error signal while maintaining the servo mute on state.

As a result, according to the present invention, the tracking error signal can be stabilized instantaneously by canceling the tracking error signal with the inverted signal having the same gain when the defect is detected.

Hereinafter, a tracking error signal stabilization method of a compact disc player according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

4 is a flowchart illustrating a tracking error signal stabilization method of a compact disc player according to an exemplary embodiment of the present invention.

1 and 4, in the tracking error signal stabilization method of the compact disc player according to the present invention, first, the RF unit 40 of the compact disc player executes a first bottom hold and a second bottom hold. In this case, the servo unit 60 determines whether a search command is transmitted from the microcontroller unit 70 (S11), and if the search command is normally transmitted, the servo unit 60 performs the same search process. (S12).

When the search command of the microcontroller unit 70 is not transmitted, the servo unit 60 determines whether the defect is detected (S13), and maintains the servo on when no defect is detected. When the defect is detected (S14), the servo is muted on (S15), and then the tracking error inversion signal and the existing tracking error (TE) are summed (S16).

Next, the servo unit 60 checks whether the defect detection is completed (S17), and then checks whether the microcontroller unit 70 has completed the determination thereof (S18). When the microcontroller unit 70 completes the determination, the servo is turned on (S19). When the microcontroller unit 70 does not complete the determination, the microcontroller unit 70 maintains the servo mute-on state. The sum of the error reversal signal and the existing tracking error (TE) signal is maintained. In this case, the tracking error signal may be unstable in two ways, a defect and a track search. However, in the present invention, when the defect is detected, the tracking error signal has the same gain as that of the tracking error (TE) signal. By canceling the inverted signal together with the original tracking error signal, the amount of excitation at the time of defect detection is canceled.

As described above, in the conventional case, when the defect is encountered, the tracking error signal is maximized immediately after the E beam-F beam of the optical pickup enters the defect area and immediately before exiting. However, in the present invention, after the defect detection, the inverted signal of the tracking error signal is added to the original tracking error signal to cancel the tracking error signals due to the defects to stabilize the excited tracking error signal. In this case, the time for adding the tracking error inversion signal is determined by the microcontroller unit 70 and optimized. Here, the inverted signal of the tracking error signal can be easily implemented by passing the tracking signal through an inverter or the like.

In addition, the tracking error signal stabilization method of the compact disc player according to the present invention is not limited to the above embodiments, and various modifications and changes can be made without departing from the technical gist of the present invention.

As described above, according to the present invention, it is possible to provide a tracking error signal stabilization method of a compact disc player capable of stabilizing an instantaneous excited tracking error signal by canceling the tracking error signal when the defect is detected with an inverted signal having the same gain. have.

Claims (5)

In the method of stabilizing the tracking error signal of a compact disc player, Iii) determining, by the servo unit, whether or not a search command has been transmitted from the microcontroller unit when the RF unit of the compact disc player executes first and second bottom hold; Ii) determining whether a defect is detected when the search command is not transmitted; Iii) muting the servo if the defect is detected; And I) canceling the sum of the tracking error reversal signal and the original tracking error signal when the defect is detected; Tracking error signal stabilization method comprising a. The method of claim 1, Iii) the microcontroller unit determining that the defect detection is complete; Iii) turning on the servo when the determination is complete; And Iii) if the determination is not completed, maintaining the sum of the tracking error inversion signal and the existing tracking error signal while maintaining the servo mute on state; Tracking error signal stabilization method further comprising. The method of claim 1, The tracking error inversion signal has the same gain as the tracking error signal and is added to the original tracking error signal to cancel the amount of excitation during detection of the defect. In the method of stabilizing the tracking error signal of a compact disc player, Iv) when the first and second bottom hold are performed from the RF unit of the compact disc player, determining whether or not a search command has been transmitted from the microcontroller unit; Ii) if the search command is transmitted, performing the existing search process in the same manner; Iii) determining whether a defect is detected if the search command is not transmitted; Iii) keeping the servo on if the defect is not detected; Iii) muting the servo if the defect is detected; Iii) adding the tracking error inversion signal and the original tracking error signal if the defect is detected; Iii) checking whether the microcontroller unit is judged when the defect detection is completed, and turning on the servo unit when the determination is completed; and Iii) if the microcontroller unit has not completed the determination, maintaining the sum of the tracking error inversion signal and the original tracking error signal while maintaining the servo mute on state; Tracking error signal stabilization method comprising a. The method of claim 4, wherein The tracking error inversion signal has the same gain as the tracking error signal and is added to the original tracking error signal to cancel the amount of excitation during detection of the defect.