JPH02230555A - Sector mark detector - Google Patents

Abstract

PURPOSE:To detect the position of a sector mark even when read data is distorted by providing a circuit to detect a first detecting signal and a circuit to output a second detecting signal at every sector of a medium, and outputting the second detecting signal when the first detecting signal coincides with the second detecting signal. CONSTITUTION:This device is provided with an A/D converter 1, a pattern detection circuit 2, a clock counter 3, a byte counter 4, a decoder 5, a coincidence detection circuit 6, and a switch 7. At an initial state, the switch 7 is controlled so as to output a media sector mark detecting signal detected by the pattern detection circuit 2. Next, the clock counter 3 outputs a byte clock by counting a channel clock, and counts the byte clock of the byte counter 4, and when the decoder 5 generates an internal sector mark detecting signal, the coincidence detection circuit 6 controls the switch 7 so as to output the internal sector mark detecting signal. Thereby, it is possible to always detect the position of the sector mark.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a sector mark detection device used in optical disc devices and the like.

BACKGROUND OF THE INVENTION FIG. 3 shows the configuration of a conventional sector mark detection device.

In FIG. 3, 1 converts the data read from a recording medium such as an optical disk as shown in FIG. 4(a) into a digital signal as shown in FIG. 4(b) using a channel clock. It is an A/D converter.

Here, if the data is in sample format 4/15, for example
When the code is written on the medium, the read data is a data pattern representing 1 byte in 15 layers, and the sector mark pattern is data “00” to “FF”.
A special pattern other than the pattern representing "OIO
It is preset to OOOIIIOOOOOOJ.

2 detects a sector mark pattern from the digital signal converted by the A/D converter 1 using the channel clock and byte synchronization signal, and generates a detection signal as shown in FIG. 4(C). This is a pattern detection circuit that outputs .

Next, the operation of the above embodiment, particularly the operation of the pattern detection circuit 2, will be explained with reference to FIG.

When the pattern detection circuit 2 obtains the values for 15 channels from the A/D converter 1 using the channel clock and byte synchronization signal, it sets the four largest values to "1" and sets the remaining values. The data pattern is converted to "0", and the converted pattern is [010000]. If it matches 11000000J, a detection signal is output.

Then, the optical disk device or the like reads and writes data in sectors on the medium based on this detection signal.

Problems to be Solved by the Invention However, the conventional sector mark detection device described above has the following problems:
Since sector marks are detected only from read data from the medium, there is a problem that if the read data is distorted due to a defect in the medium, the sector marks cannot be detected.

SUMMARY OF THE INVENTION In view of the above conventional problems, it is an object of the present invention to provide a sector mark detection device that can detect the position of a sector mark even when read data is distorted due to a defect in the medium or the like.

Means for Solving the Problems In order to achieve the above object, the present invention includes a circuit that outputs a first detection signal when a sector mark written in advance on a medium is detected, and a second detection signal for each sector of the medium. and a circuit that outputs a detection signal, and outputs the second detection signal when the first detection signal and the second detection signal match.

Effect: With the above configuration, the present invention outputs the second detection signal for each sector of the medium even when the read data is distorted due to a defect in the medium and the first detection signal is not output. can be detected.

Embodiment 5 -/ Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1st
2 is a block diagram showing an embodiment of the sector mark detection device according to the present invention, and FIG. 2 is a timing chart showing main signals of the sector mark detection device shown in FIGS.
Components that are the same as those shown in the figures are given the same reference numerals.

In FIG. 1, 1 converts read data read from a recording medium such as an optical disk as shown in FIG. 4(a) into a digital signal as shown in FIG. 4(b) by using a clock. This is an A/D converter.

Here, if the data is in sample format 4/15, for example
If the code is written to the medium in a garbled manner, the read data must be a data pattern that represents 1 byte in 15 Bouyanelles, and the sector mark pattern is data "00" to "
A special pattern other than the pattern representing "FF" is written in advance in each sector of the medium, for example, [OIOOOOIIIO
It is preset to OOOOOJ.

2 detects a sector mark pattern from the digital signal converted by the A/D converter 1 using the channel clock and byte synchronization signal, and generates a media sector mark detection signal as shown in FIG. 2(a). This is a pattern detection circuit that outputs .

3 is a clock counter that counts the channel clock using the byte synchronization signal as a reset signal and outputs a byte clock as shown in FIG. }
{As No. A, as shown in Figure 2 (C), a bite counter that counts the byte clock from clock counter 3, 5 is a bite counter that counts when the count value of the bite counter reaches the number of bytes in one sector (N+1) The decoder 5 generates an internal sector mark detection signal as shown in FIG. 2(d). Therefore, the decoder 5 generates an internal sector mark detection signal for each sector of the recording medium.

6 is a coincidence detection circuit that compares the media sector mark detection signal of the pattern detection circuit 2 with the internal sector mark detection signal generated by the decoder 5 and detects whether they match; 7 is a coincidence detection circuit; This switch selectively outputs the media sector mark detection signal detected by the pattern detection circuit 2 and the internal sector mark detection signal generated by the decoder 5 based on the detection result of step 6.

Next, the operation of the above embodiment will be explained.

First, in the initial state, the switch 7 shown in FIG. 1 is controlled to output the media sector mark detection signal detected by the pattern detection circuit 2.

Next, when the clock counter 3 counts the Tellanel cross and outputs a byte clock, the byte counter 4 counts the byte clock from the clock counter 3, and the decoder 5 generates an internal sector mark detection signal, the coincidence detection circuit 6 The switch 7 is controlled to output the internal sector mark detection signal generated by the decoder 5.

Here, since the number of ternary clocks between sectors is constant, as shown on the right side of Figure 2, the read data is distorted due to a defect in the medium, and the pattern detection circuit 2 outputs a media sector mark detection signal. Even if there is no sector mark, the position of the sector mark can always be detected because the decoder 5 outputs an internal sector mark detection signal generated for each sector.

Effects of the Invention As explained above, the present invention includes a circuit that outputs a first detection signal when a sector mark written in advance on a medium is detected, and a circuit that outputs a second detection signal for each sector of the medium. Since the second detection signal is output when the first detection signal and the second detection signal match, the h9-code data may be distorted due to a defect in the medium, etc., and the first detection signal may be distorted. Even when no detection signal is output, the position of the sector mark can be detected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the sector mark detection device according to the present invention, FIG. 2 is a timing chart showing main signals of the sector mark detection device of FIG. 1, and FIG. FIG. 4, a block diagram showing the sector mark detection device, is a timing chart showing the main signals of the sector mark detection device shown in FIG. 1... A/D converter, 2... Pattern detection circuit, 3
Clock counter, 4... Byte counter, 5...
Decoder, 6... Coincidence detection circuit, 7... Switch.

Claims (2)

[Claims] (1) A circuit that outputs a first detection signal when a sector mark written in advance on the medium is detected, a circuit that outputs a second detection signal for each sector of the medium, and the first detection signal. and a circuit that outputs a second detection signal when the second detection signals match. (2) The circuit that outputs the second detection signal includes a first counter that counts a channel clock of the medium to generate a byte clock of the medium, and a circuit that outputs the first detection signal by using the first detection signal as a reset signal. 2. A decoder for outputting the second detection signal when the value of the second counter reaches the number of bytes of one sector of the medium. 1. The sector mark detection device according to 1.