KR100236632B1 - Apparatus and method for error detecting in a compact disc - Google Patents

Abstract

The present invention detects the magnitude of a pulse width by digitally converting a signal extracted from a compact disk to a constant state value, and compares the magnitude of the detected pulse width with a previously stored value to detect fouling on the CD. A compact disc fouling detection device and a detection method capable of simplifying a circuit for detection, comprising: a pickup unit (11) for generating a light source on the CD (10) to read out a recording signal; An R / F unit 30 for filtering the read high frequency analog signal; A driving unit 50; A servo unit 20 for controlling the pickup unit 11 through the driving unit 50 based on a previous tracking and focus error; An analog / digital converter 70 for converting a high frequency analog signal output from the R / F unit 30 into digital data; A sample clock generator 100 generating a sample clock; A pulse width detector (81) for detecting a pulse width of the digitally converted data by the generated sample clock, a fouling determination unit (82) for determining whether there is a signal defect based on the detected pulse width, and the fouling determination A microcomputer (80) configured as a control unit (83) for outputting a signal according to whether or not the signal of the unit (82) is determined; And a digital signal processing unit 90 for processing the digitally converted data into a signal recognizable by the control unit 83. It is a very useful invention that can accurately determine whether or not and by eliminating the use of a separate external component for the fouling detection function, it is possible to realize the low cost and the miniaturization of the device.

Description

Device and method for detecting damage of compact disc

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a damage of a compact disk and a method of detecting the same. More particularly, the present invention relates to a pulse that has a constant state value by digitally converting an input signal extracted from a compact disk (hereinafter referred to as a CD). A compact disc that can simplify the circuit for detection of fouling by detecting the magnitude of the width in a digital state, and detecting the contamination on the CD using a microcomputer with performance margin by comparing the magnitude of the detected pulse width with a previously stored value. The present invention relates to a fouling detection apparatus and a detection method.

A conventional compact disc detection apparatus includes a pick-up unit 11 for generating a light source to the CD 10 to read a recording signal, as shown in FIG. An R / F unit 30 for filtering the high frequency analog signal read out and input; A damage interval detection circuit 40 for detecting and outputting a defect section from the filtered signal after outputting the shaping filter; And a servo unit 20 for controlling the pickup unit 11 through the driving unit 50 based on a previous tracking and focus error according to the detection signal of the fouling section detection circuit 40.

FIG. 2 is a waveform diagram of a main part in the fouling section detection circuit of FIG. 1. Referring to the waveform diagram of FIG. 2, the operation of the fouling detection apparatus of FIG. 1 will be described. The optical signal reflected from the surface where the pits of the CD are arranged is detected and converted into an electrical signal. The R / F unit 30 filters the electrical high frequency signal and outputs it as a clean signal. The servo unit 20 adjusts the position of the pickup unit 11 through the driving unit 50 to compensate for tracking and focus errors output from the pickup unit 11.

However, when the CD 10 is damaged due to scratches, dots, fingerprints, etc., when the pickup 11 irradiates this portion, light is scattered to reduce reflected light. A signal missing section A as shown in FIG. 3 is generated in the detection signal. As such, when a signal having a missing section (a in FIG. 2) is input to the fouling section detecting circuit 40, the signal is inverted and amplified through the OP amplifier 41, and the inverted amplified signal is the upper OP amplifier 43 of the next stage. The envelope below the signal is detected by (c) in FIG. 2, and the lowest level of the inverted signal is maintained by the lower op amp 42 (d) in FIG. The pulse signal corresponding to the section in which the signal is missing is outputted and is applied to the servo unit 20 by comparing with the OP amplifier 44 of FIG. In the pulse section, the pickup section 11 is controlled by the error signal before the pulse section while ignoring the currently input tracking and focus error values, so that the pickup section 11 does not significantly deviate from the track due to the signal loss section. .

However, the conventional compact disc fouling detection device, which is constructed and operated as described above, uses a separate detection circuit to determine whether there is any damage in an analog manner, and also has a large time constant resistor and a capacitor for amplification and minimum level maintenance. Since not only increases the volume of the device but also has a problem of low reliability in detecting a damage section due to a weak analog method.

Accordingly, the present invention was devised to solve the above problems, and by using a microcomputer to detect a dirty section in a digital manner, the compactness of the device can be reduced by reducing the number of parts while improving the reliability of the detection. It is an object of the present invention to provide an apparatus and a method for detecting a disk fouling.

1 shows the structure of a conventional apparatus for detecting a contamination of a compact disc,

FIG. 2 shows waveform diagrams of major parts in the fouling section detection circuit of FIG.

3 shows the change in the signal between normal and fouling time,

4 and 5 show the configuration of an embodiment of the apparatus for detecting a contamination of a compact disc according to the present invention,

6 shows a flow of a method for detecting a contamination of a compact disc according to the present invention.

* Explanation of symbols for main parts of the drawings

10: compact disc (CD) 11: pick-up part

20: Servo section 30: R / F section

40: Defective section detection circuit 41, 42, 43, 44: OP amplifier

50: drive unit 70: analog / digital conversion unit

80: microcomputer 81: pulse width detection unit

82: damage determination unit 83: control unit

90: digital signal processor 100: sample clock generator

In order to achieve the above object, there is provided a method of detecting a damage of a compact disc, the method comprising: a first step of digitally converting a signal extracted from a compact disc (CD); Detecting a constant width of the digitally converted signal; And a third step of comparing the detected width with a preset value to determine whether there is any damage, and at the time of determining the damage of the third step, maintaining a tracking error and a focus error signal before contamination. It is characterized in that it further comprises a fourth step.

In addition, the apparatus for detecting a damage of a compact disc according to the present invention includes: digital conversion means for digitally converting a signal extracted from a compact disc (CD); Pulse width detecting means for detecting a predetermined width of the digitally converted signal; And determining means for determining whether there is any damage by comparing the size of the detected width with a preset value, and controlling to output the tracking error and the focus error signal before the contamination when the judgment is made. It is characterized in that it comprises a means, the apparatus for detecting a compact disc of the compact disc according to the present invention, the digital conversion means for digitally converting the signal extracted from the compact disc (CD); Sample clock generation means for generating a sample clock for detecting a constant state width of the digitally converted signal; Pulse width detecting means for detecting a constant state width of the digitally converted signal by the generated sample clock; And determining means for determining whether there is any damage by comparing the detected width with a preset value.

In the apparatus and method for detecting a contamination of a compact disc according to the present invention configured as described above, first, the digital conversion means converts a signal extracted from a compact disc into digital data, and the pulse width detection means The pulse width is calculated from the counted value and the digital conversion rate by counting the number of data rows whose value is LOW in the digitally converted data string by the sample clock generated and output from the sample clock generating means. do. The judging means compares the size of the calculated width with a preset value, and if the size of the calculated width is larger, determines that the signal is fouled. The tracking error and focus error signals are outputted so that the servo control of the CD is performed based on this.

Hereinafter, the structure and operation of an embodiment of the apparatus and method for detecting a damage of a compact disc according to the present invention will be described in detail with reference to the accompanying drawings.

4 and 5 illustrate a configuration of an embodiment of a device for detecting a contamination of a compact disc according to the present invention, the pickup unit 11 performing the same operation as the conventional embodiment; R / F section 30; A driving unit 50; and a servo unit 20; An analog / digital converter (hereinafter, referred to as an 'A / D converter') 70 for converting a high frequency analog signal output from the R / F unit 30 into digital data; A sample clock generator 100 generating a sample clock; A pulse width detector 81 which detects a pulse width of the digitally converted data by a sample clock generated and output from the sample clock generator 100, and a damage that determines whether a signal is missing based on the detected pulse width A microcomputer (80) comprising a determination unit (82) and a control unit (83) for outputting a signal according to the determination of whether or not a signal is determined by the damage determination unit (82); And a digital signal processing unit 90 for processing the digitally converted data into a signal recognizable by the control unit 83.

FIG. 6 is a flow chart illustrating a method of detecting a contamination of a compact disc according to the present invention. Hereinafter, the flow of FIG. 6 will be described in detail with reference to the above configuration.

In the apparatus for detecting a compact disc of a compact disc according to the present invention configured as described above, the width of the analog high frequency signal extracted from the CD 10 (S2) by the same method as in the related art is that the clock pulse frequency of the CD is 4.3218 MHz. When the linear velocity is recorded at 1.25 m / sec, the recorded pit ranges from 0.8677 µm (corresponding to 3T) to 3.1815 µm (corresponding to 11T), so a minimum of 6.94 µsec (= 0.8677 µm / sec). 1.25 m / sec), up to 2.545 μsec (= 3.1815 μm / 1.25 m / sec), and this high frequency signal is input to the A / D converter 70. The high frequency signal inputted to the A / D converter 70 is sampled at a predetermined sampling rate according to the sample clock generated from the sample clock generator 100 and digitalized (S3) to convert the digital signal into a digital signal processor 90 ) And the pulse width detection unit 81, respectively.

The digital signal processor 90 processes the digital data in a signal form recognizable by the controller 83 and transmits the digital data to the controller 83. The pulse width detector 81 is configured to generate the digital data. The number of data rows whose value is LOW is detected to calculate the width of the section from which the value is low (S4). For example, the sampling frequency of the A / D converter 70 is 1 MHz. Assuming that the number of row data columns is four, the corresponding interval in the original analog signal is calculated to be at least 4 μsec (= 1 μsec × 4).

The fouling determination unit 82 compares the magnitude of the pulse width calculated as described above with a reference value that is set larger than the pulse width corresponding to 11T (2.545 µsec in the above assumption) (S5). If the predetermined damage determination value is 10 μsec, and the detected low level pulse width is 10 μsec or more (10 or more low level data strings), the damage determination unit 82 is determined. ) Determines that it is a signal loss, that is, a foul, and informs the controller 83 of the signal, the controller 83 switches the signal state applied to the servo unit 20 in the corresponding section to cause the servo unit 20 to be changed. The error signal currently read from the pickup unit 11 is notified that the error signal is read in the damaged section. Accordingly, the servo unit 20 ignores the error signals TE and FE currently being input, before the recognition of the damage. Tracking And outputting a focus error signal by controlling (S12) the pick-up unit 11, the pick-up unit 11 is to ensure that due to fouling of the signal greatly deviate from the track.

The apparatus and method for detecting a compact disc according to the present invention configured and operated as described above, by detecting a defect section of a signal in a digital manner and determining whether or not there is a damage, can accurately determine whether or not there is a damage. By incorporating this function into the microcomputer, the use of a separate external component for the fouling detection function is eliminated, thereby making it possible to realize low cost and miniaturization of the device.

Claims (6)

A first step of digitally converting a signal extracted from a compact disc (CD); Detecting a constant width of the digitally converted signal; And a third step of determining whether there is any damage by comparing the detected width with a preset value. The method of claim 1, further comprising: a fourth step of outputting a tracking error signal and a focus error signal before the fouling, in the case of determining the fouling of the third step. Digital conversion means for digitally converting a signal extracted from a compact disc (CD); Pulse width detecting means for detecting a predetermined width of the digitally converted signal; And determining means for determining whether or not there is a damage by comparing the detected width with a preset value. The apparatus of claim 3, further comprising: control means for outputting a tracking error signal before focusing and a focus error signal when the judgment of the determination means is made. The apparatus of claim 3, wherein the set value is equal to or larger than a pulse width detected from the longest pit recorded on the compact disc. Digital conversion means for digitally converting a signal extracted from a compact disc (CD); Sample clock generation means for generating a sample clock for detecting a constant state width of the digitally converted signal; Pulse width detecting means for detecting a constant state width of the digitally converted signal by the generated sample clock; And determining means for determining whether or not there is a damage by comparing the detected width with a preset value.

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