JPS6233370A - Data recording error detector for optical disc - Google Patents

Abstract

PURPOSE:To prevent generation of an abnormal clock by providing an error detection and correction means for detecting and correcting an error of a recording signal and a means for switching a range keeping synchronization with the recording signal of an automatic phase control circuit depending on the verified read time and the normal reproduction time. CONSTITUTION:When the response speed is fast, the titled device is sensitive to external noises and causes easily an abnormal clock. In increasing the natural frequency at the verify read time more than that at the normal reproduction time, the abnormal clock at the normal reproduction is prevented. Further, the inherent frequency is increased, then the synchronization keeping range is widened. Thus, a switch 22 in an automatic phase control circuit 17 is changed over to be connected to a capacitor C2 at the reproduction or a switch 23 is clanged over to the position of a resistor R4, then the range of keeping the inherent frequency and the synchronization is widened and the circuit 17 is more sensitive to noise due to decentering an optical disc 8 or noise due to aging deterioration of the optical disc 8 than that at the normal reproduction. Thus, the abnormal clock is prevented and the probability of mis-reproduction is minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disc C: a detection device for detecting errors in recorded data'.

[Conventional technology]

FIG. 5 is a block diagram of a recording format for recording user data on an optical disc (: FIG. 6 is a block diagram of a conventional system for recording data on an optical disc and reproducing the recorded data. In Figure 2, (1) is user data to be recorded, (21 is a sync pattern for checking C2 synchronization for each sector, (3) is a chain status indicating the chaining state of sectors, ( 4) is an error correction code that can detect errors in user data (1) during recording, and these (1) to (41) constitute the recording format (5) of one sector. 6
In the figure, (6) is an error correction encoding means for generating an error correction code (4) from the user data (1) to be recorded;
(7) is a modulator that modulates 51 in the recording format in synchronization with the reference clock signal in the signal line a, in order to reproduce the user data (1) information and the reproduced clock without error; The optical disc is a recording medium, and the modulator (
Signal C of recording format (5) modulated by 7)
: Laser beam that is controlled on and off according to the timing (Fig. This is an automatic phase control circuit that inputs a signal and generates a reproduced clock synchronized with the signal from the signal line, and is configured as shown in Figure 7. In Figure 7, αO changes frequency depending on the control voltage. The voltage controlled oscillator (Ql) is a phase detector that compares the phase of the output signal of this voltage controlled oscillator (1G output signal and the modulated recording format (51) output from the optical disk 18+. , (L is a low-pass filter that removes the high frequency component of the output of the phase detector section, and the output voltage of this filter is supplied to the voltage controlled oscillator as a control voltage. (13 is the clock reproduced by the automatic phase control circuit (9) (2) Therefore, the modulated recording format taken out from the optical disc (8) (
C9 is a demodulator that demodulates the signal of C9. 1 is a switching circuit that switches the error correction capability of the error detection and correction means (14) and the timing of demodulating the recording signal of the automatic phase control circuit (9) during normal playback and during verify reading, which will be described later.
When 151 is switched during verify read, when the number of errors detected by the error detection and correction means (1 (a) exceeds the specified number), the alternate sector informs that the user data (1) will be rewritten in the alternate sector of the optical disk. An alternating sector signal generator that generates a signal.

Next (: Explain the operation.

An error correction code +41 that enables detection and correction of errors after recording is generated from user data (1) to be recorded in an error correction encoding means (61), and after forming a recording format (51), this recording format ( 51 is modulated by a modulator (7) in synchronization with a clock signal.

A laser beam is controlled by the signal modulated by the modulator (7), and the modulated signal is recorded on the optical disk (8) by this laser beam.

Each time the user data (1) recorded on the optical disc 181 is recorded, it is checked whether it is recorded correctly, and if it is recorded incorrectly, the same user data (1) is written to another sector. Repeat (verify read). During this verify read, as well as during normal playback,
The signal of the modulated recording format (5) is converted into an electric (:
Take it out. Inputting the extracted modulated recording format (5) signal to the automatic phase control circuit (9) (: thereby reproducing a clock synchronized with the recording format (5) signal, as shown in FIG. 7). The signals constituting the modulated recording format 15 output from the optical disk (8) are input to the automatic phase control circuit (91), and the input signal and the output signal of the voltage controlled oscillator section are The phase is compared with a phase detector αυ, and the phase difference C between the two is converted into a matching voltage with a low-pass filter α2,
By feeding it back to the voltage controlled oscillator Ql as a control voltage, a clock synchronized with the signal making up the recording format [51] is reproduced.

After demodulating the signal of the recording format (5) modulated by the automatic phase control circuit 19+ in accordance with the clock reproduced through the signal line by the demodulator (13), the error detection and correction means I determines whether there was an error during optical disk recording. Errors are detected and corrected by referring to the error correction code (4) added to the recording format (51). At this time, if the error is within a correctable range, the user data is (1) is extracted and becomes reproduced data, and when the error exceeds the correctable range, an error signal is generated through the signal line C. In response to this error signal, the alternate sector signal generator (lE9) )
A replacement sector signal is generated to notify that the user data will be rewritten.

[Problem that the invention seeks to solve]

In the conventional optical disc data recording error detection device as described above, by switching the switching circuit - during verify reading, the timing of the reproduction clock passing through the signal line of the automatic phase control circuit +91 is adjusted according to the recording format (5).
The direction in which synchronization is more likely to be lost during demodulation than during normal playback (
Errors are detected by shifting the error correction capability of the error detection and correction means (14) by two specified values, or by lowering the error correction capability of the error detection and correction means (14) compared to normal playback, and detect errors in the user data (1). 2) By writing the error-free recording format (5) again, recording errors were prevented during normal playback.

However, with this method of detecting recording errors, as shown in FIG.
If noise A is generated due to eccentricity of data 1, etc., the automatic phase control circuit (91) is activated at that point to synchronize with the noise and generate abnormal clock B until the next data rise. By teaching a large number of data to be read during demodulation due to the occurrence of abnormal clock B, the subsequent data (= also being taught a lot,
There was a problem in that bit misalignment occurred and correct data could not be reproduced. This invention was made to solve this problem, and prevents the automatic phase control circuit from generating an abnormal clock during normal playback, making it possible to demodulate and play data more reliably than before. The purpose of this invention is to obtain a data recording error detection device for optical discs.

[Means for solving problems]

The data recording error detection device for an optical disc according to the present invention includes an automatic phase control circuit that inputs a recording signal output from an optical disc and reproduces a clock synchronized with the recording signal; , an error detection and correction means for detecting and correcting errors in the recorded signal, and a switching means for switching the range in which synchronization between the automatic phase control circuit and the recorded signal can be maintained between during verify reading and during normal playback. We are prepared.

[Effect]

In this invention, the range in which synchronization with the recording signal of the automatic phase control circuit can be maintained during verify read and normal playback is switched by a switching means (:
Therefore, by creating a state in which abnormal clocks are likely to be generated during verify reading, and detecting data recording errors using the error detection and correction means in this state, the generation of abnormal clocks during normal reproduction is prevented.

〔Example〕

FIG. 1 is a diagram illustrating the configuration of a data recording/reproducing system including an optical disk data recording error detection device showing an embodiment of the present invention. ill~181 (13~(L61 is exactly the same as the above-mentioned conventional device. The wholesaler is an automatic phase control circuit having a switching means that can switch the synchronization holding range during verify read and during normal playback. , Fig. 2 1: The structure is as shown in Fig. 2. In Fig. 2, a & is a voltage controlled oscillator, the wire is a phase detector, and Rr is a voltage controlled oscillator.
, R2 is a resistor, ■ is an operational amplifier, 01.02 is a capacitor (Ot)Ox) in a different container, and these resistors 01
．． 02, operational amplifier ■, and capacitors 01 and 02 constitute a low-pass filter (2υ).

R is a resistance, R3 and R4 are resistances (B
E>R4), @@ is the verify IJ that passes through the signal line d.
The signal C is output from the switching circuit (one (Fig. 1)) when the signal is switched, and the switch (C) plays the role of an attenuator. When inputting to αl,
This is a frequency divider circuit that adjusts the frequency in advance.

If a low-pass filter in a general automatic phase control circuit aiζ has a circuit as shown in FIG. 3, the phase transfer function of the automatic phase control circuit η is expressed by

Here, n = OR1, Tz = OR2 is the product of the gain of the voltage controlled oscillator α seconds and the phase detector (19).

is the quantity that influences the response of the system (hereinafter referred to as natural frequency), which is the phase transfer function H (81) of the dynamic phase control circuit (17), which shows the characteristics of the transient state C of the automatic phase control circuit (17). The vertical axis represents the output response of the phase error to a step input (:), and the horizontal axis represents the C time response.

From this figure, it can be seen that with respect to the phase error due to noise 1: the response speed is fast when the natural frequency is large, and the response speed is slow when the natural frequency is small. A fast response speed means that the device is sensitive to external noise, making it more likely to generate an abnormal clock. Therefore, by making the natural frequency larger during verify read than during normal playback, abnormal clocks during normal playback can be prevented. Furthermore, the relationship between the natural frequency and the synchronization holding range ωL is ωL = 2ζωn, and as the natural frequency increases, the synchronization holding range ωL
It also becomes wider. Therefore, in the device according to invention C, the low-frequency fill c! in the automatic phase control circuit (1'I) as shown in FIG. The configuration is such that the value of the capacitor D can be changed between the verify read and the normal playback by using the switch @(: or the resistors R3 and R4 with the switch.) Next, operation C: will be explained. .

Figure 1 1: The operation during recording of the data shown is the same as the conventional one. During playback (: indicates the switching circuit at the time of verify read ← from the signal line d (2 output signal C: from the automatic phase control Switch the switch in the circuit←η to connect it with the capacitor C2, or connect the switch with the resistor R4.
(: When switched, as mentioned above, the natural frequency and synchronization holding range become wider, and the automatic phase control circuit's internal frequency becomes wider during recording (noise due to eccentricity of the binary disc (8), etc.),
8) becomes more sensitive to noise due to deterioration over time (-) than during normal playback. From this (2), abnormal clocks are more likely to occur, and the recording format (5) of the sector where an abnormal clock occurs is set to error detection and correction. If the error exceeds the range that can be corrected by means I, an error signal is generated on signal line C,
In response to this error signal passing through the signal line O, an alternate sector signal generator (le) generates a signal informing that user data will be rewritten in the alternate sector of the optical disk (8).

Another example is when verifying read! = Increasing the natural frequency 1: A similar operation can be performed by providing a switch that sets the time constant of the low-pass filter η to be smaller than that during normal reproduction. As another example, the same operation can be obtained by providing a switch that makes the gain of the voltage controlled oscillator U or phase detector (II larger than those during normal reproduction (-) during verify read. I can do it.

〔Effect of the invention〕

As described above, according to the present invention, the range in which synchronization with the recording signal of the automatic phase control circuit that inputs the recording signal output from the optical disk and can maintain synchronization with the recording signal of the automatic phase control circuit that reproduces the clock synchronized with the recording signal is Switching means C: Switching between verify read and normal playback 1: Prevents abnormal clocks caused by eccentricity of the optical disk, deterioration over time, etc., and reduces the probability that user data will be erroneously played back. can be minimized and the reliability of recorded data can be improved.

[Brief explanation of drawings]

FIG. 1 shows data recording including an optical disk data recording error detection device showing an embodiment of the present invention. A regeneration system configuration diagram, FIG. 2 shows the specific circuit factors of the present invention, FIG. 3 shows an example of a low-pass filter, and FIG. 4 shows the characteristics of the automatic phase control circuit in a transient state. Fig. 5 is a block diagram of the recording format, Fig. 6 is a block diagram of a system for recording data on a conventional optical disc and reproducing the recorded data, Fig. 7 is a principle diagram of an automatic phase control circuit, and Fig. 8 The figure is a diagram showing the occurrence of an abnormal clock. In the figure, (17) is an automatic phase control circuit, (14) is an error detection and correction means, and C! 21 (231 is a switch indicating a switching means. The same reference numerals in each figure indicate the same or corresponding parts.

Claims (4)

[Claims] (1) An automatic phase control circuit that inputs a recording signal output from an optical disk and reproduces a clock synchronized with the recording signal, and reproduces the recording signal according to the timing of the clock and corrects errors in the recording signal. An error detection and correction means for detecting and correcting the error, and a switching means for switching a range in which synchronization of the automatic phase control circuit with the recording signal can be maintained between during verify reading and during normal playback. Data recording error detection device for optical discs. (2) The data recording error detection device for an optical disc according to claim 1, wherein the switching means switches to widen the range in which synchronization is maintained during verify reading. (3) The data recording error detection device for an optical disk according to claim 1, wherein the switching means is a means for switching the time constant of a low-pass filter in the automatic phase control circuit. (4) The data recording error detection device for an optical disk according to claim 1, wherein the switching means is an attenuator that attenuates the input voltage of the variable frequency oscillator in the automatic phase control circuit.