JPS63279471A - Detection method for sector mark of optical disk device - Google Patents

Abstract

PURPOSE:To detect a sector mark by detecting a sector mark in providing a specified condition by use of a reproducing signal showing a state of the bit being recorded when the bit is not reproduced due to a fault or even when the disaccordance in >=2-bit is generated. CONSTITUTION:In a sector mark detecting condition, in one expected value either '0' or '1', the number of allowable disaccordance bits is made one bit, and that an error over a length of two pieces of independent bits and a discrepancy over three or more bits subsequent to normal bit are allowed in case of the other expected value of the said two. In such a way, the allowable disaccordance bit numbers are set in different values corresponding to the expected values. As a result, even in the event of an independent error over up to two bits or a discrepancy over three or more bits, a sector mark can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sector mark detection method, and more particularly to a sector mark detection method for an optical disc device for processing a reproduction signal of a preformat section of the optical disc device.

[Prior art] Figure 4 shows 1, for example, "Nikkei Electronics" (1983
FIG. 2 is a diagram showing a sector recording format shown in "Large-capacity optical disk file device capable of recording code information" (published November 210, 2015, pp. 189-213). In the figure, SM (6) is a sector mark indicating the beginning of each sector, ID (8) is an address indicating the position of the sector,
(1-IECK(9) is a check bit for error detection in address (8), 5YNC1,(7) is address (
8) and inspection pitch I-(9) synchronization signal, FLAG (
11) is a flag that records the sector usage status, 5YNC
3 (10) is a synchronization signal for flag (11), DATA field (13) is a data field that records actual user data, 5YNC2 (12) is a synchronization signal for data field (13), and gap (16) is for optical disc. This is a gap to absorb jitter during rotation.

FIG. 5 is a diagram showing the signal system of the optical disc device. In the figure, a detector (19) reproduces information from an optical disc medium (18) and outputs one analog reproduction signal (17). The waveform processing circuit (2o) outputs an analog reproduction signal (17
) into a digital reproduction signal (4). The sector mark detection processing circuit (21) compares the digital reproduction signal (4) and the sector mark pattern to detect the sector mark, and detects the sector mark at the end position of the sector mark.
5) Output.

6th (2ff) is a diagram showing an example of sector mark (6).

FIG. 7 is a block diagram of the sector mark detection processing circuit of FIG. 5. In the figure, a multi-stage shift register (1) takes in a reproduced signal (4) using a clock (3) and converts this signal from serial to parallel. The pattern detection circuit (2) detects a sector mark from the output of the multi-stage shift register (1) based on the first equation below.

FIG. 8 is a diagram showing the operation timing of FIG. 7.

The first equation is the conventional sector mark detection condition, which allows a 1-bit error at any position, and is configured using a ROM or logic array in the pattern detection circuit (2) in Figure 7. has been done.

Pattern detection signal DET1= ■, 6υls DI3D+zD++D+oDsDa'
DtDsDsD4DzDzD++D16DISD14
-DIJllDI. [l*[1, [17D, ll5D,
D, D2[1゜+016D+sD+J+3 DzD+
. DJsDtDsDsDJJiD1+016DISDI
4DI3DI2DIIDI. D, D, D, 0.05D,
D, D.

”01601 SDI-DI:1D12011DI
oDJsDtDJsDJJ2 Here, soil indicates a logical sum.

A conventional sector mark detection circuit is configured as described above.
The analog reproduction signal (17) is reproduced by the detector (19) from the optical disc medium (18).

The waveform processing circuit (20) converts it into a digital reproduction signal (4), which is then sent to the multi-stage shift register (3) by the clock (3).
1). In this multistage shift register (1), the reproduced signal (4) is serial-parallel converted and outputted to Q, ~Q, and inputted to the pattern detection circuit (2), ~[)+a, shown in Fig. 7. Ru.

This pattern detection circuit (2) performs pattern detection under the conditions of the first equation, and outputs the result as a detection signal (5).

The sector mark detection state is as shown in FIG.

Here, since pattern A is a pattern without errors,
To detect.

Pattern (B) is the bit recording position (hereinafter 2 expected value “1
The state where there is no bit (referred to as °°) (hereinafter referred to as playback value "0")
Pattern (C) is a 1-bit error pattern in which a bit is present (hereinafter referred to as a reproduced value "1n") at a non-bit recording position (hereinafter referred to as 2 expected value "O"), and both patterns are detected. (D), (E).

(F) all have errors of 2 or more pits, so the reproduced signal does not become a sector mark and is not detected. As shown in Figure 8, the sector mark of the 2-period reproduction signal (4) When the pattern is taken into the multi-stage shift register (1) and the last bit of the 17th period is taken in, D16 to D.

The sector mark patterns are output in parallel. When the pattern of DI6 to D matches the first equation, a 1 detection signal (5) is output.

[Problems to be solved by the invention] In the conventional sector mark detection method as described above, the first
A lick that performs pattern detection using a formula.

If an error of 2 or more bits occurs, it cannot be detected, and looking at the actual occurrence of errors, the probability of a small error occurring is high, so a sector mark failure due to a mismatch of 2 bits or more is impossible. There was a problem that detection often occurred.

This invention was made to solve this problem, and it is possible to detect sector marks even when there is a discrepancy of two or more bits in the reproduced signal, and even if there is a small error, sector marks can be detected. An object of the present invention is to obtain a sector mark detection method that can suppress detection.

"Means for Solving the Problems" The sector mark detection method according to the present invention sets the sector mark detection condition to an expected value of "0" or 1°.

For one expected value, the number of mismatched bits allowed is 1
For example, in the other expected value, an independent 2-bit error and a mismatch of 3 or more consecutive bits to a normal bit are allowed.

By setting the allowable number of mismatched bits to different values depending on the expected value, the occurrence of non-detection of sector marks is suppressed.

[Operation] In the present invention, the detection conditions are set to allow independent errors of 2-bit length and mismatches of 3 or more consecutive bits to normal bits.

Sector marks can be detected even if independent errors up to 2 bits in length or mismatches of 3 or more bits occur.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the pattern detection circuit according to the present invention using a logic array. The circuit (52) outputs an output signal (51). Also,
The detection signal (5) is output as the sum of the detection signals of the detection circuits for each term expressed by the second equation.

FIG. 2 is a configuration diagram showing the detection circuit of the eighth term expressed by the second equation. In the figure, the detection signal (53) is the output signal of the detection circuit in the eighth term of the second equation.

FIG. 3 is a configuration diagram showing the detection circuit of the 11th term expressed by the second equation. In the figure, the detection signal (54) is the output signal of the detection circuit in the eleventh term.

In the sector mark detection method configured as described above, the operations prior to the operation of the pattern detection circuit are the same as those in the conventional example, and therefore the description thereof will be omitted.

The pattern detection circuit (2) shown in FIG. 7 performs pattern detection according to the conditions of the second equation below.

The result is output as a detection signal. The second equation is shown below.

Pattern detection signal DET, 2 = +Dl　60+　50140+　3　　　　B.

DsOJt口5OsD-Ro30201+D+5D1SD
I40+3012 DsDsD7DsDsDJ
3D2D1”DI6D15D14013Dl□[1,,
D, D, D, DSD, D3D2D.

+011+DISDzDIJ12DllDl. D-Da
DtD6DsD+DJ2D++D16D, 5D14D1
．． D12D11D1oD, D8D7D6D5D, D, D
2Dl Here, t indicates the logical sum as described above.

In the sector mark detection state shown in FIG.
) is an error-free pattern and will be detected. pattern(
B) is a 1-pill error pattern in which the expected value is ``1'' and the reproduced value is ``0'', and pattern (D) is the expected value ``0'' and the reproduced value is ``1''.

Detection is performed using the 8th term and the 4th term or the 5th term of the second equation, respectively. Pattern (C) is a 2-bit error pattern in which the expected value is ``0'' and the reproduced value is ``1'', and the expected value is ``1'' and the reproduced value is ``O'', and is not detected.

On the other hand, pattern (E) and pattern (F) have an expected value of “0”
This is a pattern in which the reproduction value "1" is consecutive for 4 bits and 2 bits, respectively, and both are regarded as a 1-bit error according to the 15th term and the 6th term of the second equation, and a sector mark is detected.

As a result, as shown in Fig. 8, the reproduced signal (
4) into the multistage shift register (1), and when the last bit is fetched in the 17th cycle, D16 to D,
The sector mark patterns are output in parallel. When the sector mark pattern of D4 to D1 matches the second equation, the 1st period detection slope of the 17th period (
5) is output.

In addition, in the above embodiment, the expected value "0゛° and the reproduced value"
We have shown the second equation in which the detection conditions are relaxed for an error of 1", but this equation is based on the sector mark pattern and the defect characteristics of the optical disk medium. This equation is based on the detection conditions for the expected value "0" and for the expected value "1". By setting the detection conditions independently from the detection conditions! & Appropriate detection conditions can be obtained.

In addition, although the above embodiment describes sector mark detection in an optical disk device, it is also possible to improve the ability to detect identifiers in devices that use identifiers detected by pattern matching such as flag detection, or other identifiers such as magnetic disk devices. It is valid.

[Effects of the Invention] As explained above, in this invention, the sector mark detection conditions are set so that the sector mark can be detected even when a mismatch of 2 or more bits occurs. The effect is that it can be suppressed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the pattern detection circuit according to the present invention, FIG. 2 is a block diagram of the detection circuit of item 8 expressed by the second equation, and FIG. 11 is a block diagram of the detection circuit, FIG. 4 is a sector recording format diagram of an optical disk device, FIG. 5 is a signal system diagram of an optical disk device, FIG. 6 is an example of an optical disk device sector mark, and FIG. 5
The block diagram of the sector mark detection processing circuit shown in Fig. 8 is the block diagram of the sector mark detection processing circuit.
FIG. 9 is an operation timing diagram, and FIG. 9 is a sector mark detection state diagram. In the figure, (1)...Multi-stage shift register 1 (2)
... pattern detection circuit, (3) ... clock. (4)...Reproduction signal, (5)...Detection signal, (51
)...Output signal of the detection circuit in the 15th term of the second equation, (5
2)...Detection circuit of the 15th term of the second equation, (53)...
- Detection signal of the 8th term of the second equation, (54)...This is the detection signal of the 11th term of the second equation. Note that the same reference numerals in each figure indicate the same or corresponding parts. Figure 2 Figure 4 Figure 6 Figure 9 Figure 5 King, XEDLI error rank! Yumi 5ξ27ε, ノ'+11 muni: S ni no ゛1 ``゛ku,
'-? ＞ "r#に!l!!!!'l"
5 capital procedural amendments September 9, 1986

Claims (1)

[Claims] In an optical disc device equipped with a pattern detection circuit that detects a sector mark pattern consisting of pit recording areas and non-pit recording areas that are alternately consecutive, there are two cases in which pits are not reproduced due to a defect, and cases where pits are not reproduced due to a defect. The following (1) to (
3) A sector mark detection method for an optical disc device, characterized in that sector marks are detected under the conditions set forth in item 3). (1) The sector mark detection condition is satisfied if only one bit error occurs that does not result in a pit presence state at the pit recording position. (2) The sector mark detection condition is satisfied when an error occurs at only one location where the pit presence state is within two consecutive bits at a non-pit recording position. (3) Transition from a state with no pits to a state with pits at a non-pit recording position, continue in the state with pits until the next pit recording position, and then move through the pit recording position to a non-pit recording position. If an error that normally transitions to a pit-free state occurs at only one location, the sector mark detection condition is satisfied.