JPS61208634A - Information reproducing device - Google Patents

Abstract

PURPOSE:To prevent disabled tracking by providing a count means counting the number of times of code error detection and a control means controlling a loop gain of a focusing device a pickup reproducing digital information or that of a tracing device to a recording medium face. CONSTITUTION:A signal reproduced by an optical pickup 2 is converted into a digital signal by a preamplifier circuit 4 and a waveform shaping circuit 5, a clock component is extracted further by a clock recovery circuit 6 and a signal subject to an EFM modulation is demodulated by an EFA demodulation circuit 7 and the result is inputted to an error detection and correction circuit 8. The error detection and correction circuit 8 detects and corrects an error in the EFM demodulation signal in the unit of one information frame and outputs one pulse as error information when >1 code error in one information frame. The pulse of the error information is counted by a microcomputer 14 in the unit of, e.g., 1sec and the mean value in the unit of 10sec is obtained. Then flaws or dirt of the recording medium are detected surely independently of the kind to prevent tracking defect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an information reproducing apparatus, and particularly to an apparatus for detecting scratches, dirt, etc. on a recording medium.

[Prior Art] Conventionally, a CD type digital audio disc player (hereinafter abbreviated as a CD player) is known as this type of device.

In this CD player, in addition to the audio signal converted into a PCM code, a synchronization signal, a control signal, and a parity signal for error correction are added and recorded on a disc-shaped recording medium. Each signal is picked up by an optical pickup, decoded into an identifiable digital signal, subjected to error correction processing, and then converted into an analog signal, which is then played back from a speaker.

In this case, if there are scratches, dust, etc. on the disk that is the recording medium, the reproduced signal of this part will be corrected by error correction processing, but if there are scratches or the like that exceed the error correction ability, interpolation processing will be performed. The reproduced signal is approximated by However, if there are large scratches, the optical pickup may no longer be able to track and deviate from the concentric recording tracks.

Therefore, in the past, dirt and scratches on the disc surface were detected,
There is a device shown in FIG. 3 that prevents tracking from becoming impossible.

In Figure 3, (1> is a disk, (2) is an optical pickup, (3) is a disk motor that rotates the disk (1), and (4) is a preamplifier that processes the signal from the optical pickup (2). circuit, (5) is a waveform shaping circuit that converts into a digital signal, (6) is a clock regeneration circuit that extracts a clock component, (7) is an EFM demodulation circuit, (8)
) is an error detection and correction circuit, (9) is a D/A converter that converts a digital signal to an analog signal, (10) is an analog signal processing circuit, and (11) is an optical pickup (2).
); (12) is a CLV servo circuit that controls the disk motor (3); (13) is a CLV servo circuit that controls the disk motor (3);
) is a disc scratch/stain detection circuit.

In the above configuration, the signal reproduced by the optical pickup (2) is separated and combined into a signal for information regarding the reproduced sound and a signal necessary for the pickup servo circuit (11) inside the preamplifier circuit (4). . The scratch/stain detection circuit (13) detects scratches or stains on the disc (1) using information called an HF or RF multiplied signal contained in the information signal regarding the reproduced sound.

In this case, as shown in the waveform diagram of FIG. 4(a), the HF signal is normally reproduced with a certain level of amplitude, but the amplitude level decreases in the portion X where there are scratches or dirt. Therefore, the detection circuit (13) detects that the level of the HF signal has fallen below a certain reference level, and at this detection timing generates a detection pulse as shown in FIG. The tracking in (11) is varied to prevent tracking from becoming unstable due to scratches or dirt.

[Problems to be solved by the invention] However, some types of scratches and dirt do not cause a drop in the level of the HF signal, so such scratches and dirt cannot be detected and tracking becomes impossible. There was a problem with falling.

The present invention was made to solve the above-mentioned problems, and its first purpose is to reliably detect scratches and dirt on the disk surface regardless of the type, and to ensure that tracking is not possible. An object of the present invention is to provide an information reproducing device that can prevent the above problems. A second objective is to provide an information reproducing device that can quantitatively display and warn the user that there are many scratches and stains.

[Means for Solving the Problems] In order to achieve the above first object, the present invention includes a counting means for counting the number of code error detections in error correction processing, and a disc counting means for counting the number of code error detections in the error correction process, and a disk according to the counted number of code error detections. The present invention is provided with a control means for controlling the loop gain of a focusing mechanism of a pickup that reproduces digital information from a shaped recording medium or a tracking mechanism for the recording medium surface. Furthermore, in order to achieve the second objective, in addition to the above-mentioned means, a display means for quantitatively displaying the counted number of code error detections is provided. A focusing mechanism (focus servo mechanism) and a tracking mechanism for the recording medium surface (
The loop gain of the tracking servo mechanism is varied,
This prevents tracking from becoming impossible. Additionally, an error detection circuit is displayed, quantitatively informing the user that there are many stains and scratches.

[Example] The present invention will be described below based on illustrated embodiments.

FIG. 1 is a block diagram showing an embodiment of the present invention, in which a microcomputer (14) and a display (15) are provided in place of the conventional flaw/stain detection circuit (13).

The microcomputer (14) has an error detection and correction circuit (8
) is counted, and when the counted value exceeds a certain level, this counted value is displayed on the display (15).
The loop gain of the pickup servo circuit (11) is varied in accordance with the count value of the number of error detections.

In the above configuration, the signal reproduced by the optical pickup (2) is converted into a digital signal by the preamplifier circuit (4) and the waveform shaping circuit (5). Thereafter, the clock component is outputted later by the clock regeneration circuit (6), and roughly EFM' (E
Ijht to' Fourteen Hodulat
ion> The modulated signal is demodulated and input to the error detection and correction circuit (8).

The error detection and correction circuit (8) detects and corrects errors in the EFM demodulated signal in units of one information frame (588 bits), for example, based on a principle combining a Reed-Solomon code and a cross-interleaving method.

If there is one or more code errors within one information frame, one pulse is output as error information. The pulses of this error information are counted by the microcomputer (14), for example, in units of 1 second, and the average value for each 100 seconds is roughly calculated.

FIG. 2 is a flowchart showing the process of counting pulses of error information, and in order to count the number of error detections in the first 1 second interval under the condition that the reproduction operation mode is set, the count interval counter value N is set to N-1. (Step 20>. After this, the number of error detections in the first 1 second interval is counted (Step 21), and the current value is stored in the error counter E (N>) (Step 22).
).

Next, the count section counter value N is updated on the condition that N≠10 (step 23), and the number of error detections in the second grain section is counted in the same way as in the first grain section.

Such processing is repeated until N=10, and when the number of error detections in 10 seconds is obtained, the average value E of the number of error detections in each section is calculated (step 24), and the average value If E is "1000" or more, it is transferred to the display (15) and displayed,
The loop gain of the pickup servo circuit (11) is varied (step 25).

By the above-described operation, scratches and dirt can be reliably detected regardless of the type, and tracking failure can be reliably prevented. Additionally, the user is warned of an abnormally large number of scratches and dirt by showing a quantitative value.

In the above embodiment, the number of error detections is counted by a microcomputer, but a counter circuit or the like may also be used.

[Effects of the Invention] As explained above, the present invention includes a counting means for counting the number of code error detections in error correction processing, and a pickup for reproducing digital information from a recording medium according to the counted number of code error detections. The focus of - □, II! control the loop gain of the tracking mechanism relative to the structure or recording medium surface,
The system provides a means of control.

Therefore, scratches and stains on the recording medium can be reliably detected regardless of their type, and tracking failure can be reliably prevented. Furthermore, if a display means for displaying the number of code error detections is provided, it is possible to warn the user that there are abnormally many scratches or stains by showing a quantitative value. As a result, the cleaning of scratches and dirt is encouraged, and stable playback operation can always be guaranteed.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the Ann invention, Fig. 2 is a flowchart showing a process for counting the number of error detections, Fig. 3 is a block diagram showing the configuration of a conventional device, and Fig. 4 is a conventional device. FIG. 3 is a waveform diagram illustrating the operation of a circuit for detecting dirt and scratches on the disk surface in the apparatus. (1)...disc, (2)...optical pickup,
(8)...Error detection and correction circuit, (11)...Pickup servo circuit, (14)...Microcomputer, (15)...Display device. Agent: Patent attorney Masuo Ohone (2 others) Figure 1: 112! ! ! f

Claims (2)

[Claims] (1) Information that picks up digital information encoded and recorded in a predetermined encoding format on a recording medium, decodes this picked up digital information, performs error correction processing, converts it into an analog signal, and outputs it. The reproducing apparatus includes a counting means for counting the number of code error detections in the error correction process, and a focusing mechanism of a pickup or a tracking mechanism for the recording medium surface for reproducing digital information from the recording medium according to the counted number of code error detections. 1. An information reproducing device comprising: control means for controlling loop gain. (2) Information that picks up digital information encoded and recorded in a predetermined encoding format on a recording medium, decodes this picked up digital information, performs error correction processing, converts it into an analog signal, and outputs it. The playback device includes a counting means for counting the number of code error detections in the error correction process, a display means for displaying the counted number of code error detections, and a display unit for displaying digital information from the recording medium according to the counted number of code error detections. 1. An information reproducing apparatus comprising: a control means for controlling a loop gain of a focusing mechanism of a pickup to be reproduced or a tracking mechanism for a recording medium surface.