JPS63166072A - Detecting device for sector mark - Google Patents

Abstract

PURPOSE:To accurately detect a sector mark without detecting a resembled mark as the sector mark erroneously even when possibility to generate the resembled mark exists, by preventing a mark resembled to the sector mark from being outputted if it is generated in a period except the generation period of a window signal. CONSTITUTION:Since the window signal of a window signal generation circuit 16 is generated with a timing when the sector mark detecting signal of the next sector is outputted, the detecting signal is outputted when the sector mark of one sector is detected. During the period, when a mark SM' that is the resembled mark is detected, and the sector mark detecting signal is generated, the detecting signal is blocked by a gate 18 and is not outputted because no window signal is generated at the timing when the sector mark detecting signal is generated. Thus, the pseudo mark SM' is not detected as the sector mark erroneously even when it is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a sector mark detection device that is used in optical disk devices and the like and detects a sector mark indicating the beginning of a sector.

Conventional technology Figure 4 shows a recording disk (disk) used in an optical disk device.
It shows. In FIG. 4, 1 is a disk;
This disk 1 has tracks formed in a spiral shape. Each track is composed of a plurality of sectors (for example, 16 sectors). Note that FIG. 4 shows an example in which one track is composed of eight sectors. Black dots 2 in FIG. 4 indicate sector marks placed at the beginning of each sector.

FIG. 6 shows a conventional sector formant. In FIG. 6, 3 is a sector mark (SM).

4 is an ID section for recording addresses and the like, and 5 is a data section. FIG. 7a shows an example of a sector mark (SM), and this sector mark (8M) consists of a 0 part of time width A, 1 part of time width B, and 1 part of 1 time width C.

FIG. 6 shows a sector mark detection circuit for detecting the sector mark shown in FIG. 7a. In FIG. 6, 6 is an input terminal to which the signal picked up from the disk 1 is applied, 7a is a large time width detection circuit, and this time width A detection circuit 7a detects the sign of the signal input to the input terminal 8. The time width between conversion points is detected by the number of sampling pulses, and when the detected time width matches the time width A, the detection pulse (
Figure 7b) is output. Similarly, 7b and 7c are detection pulses when time widths B and C are detected respectively (Fig. 7c, d).
These are a time width B detection circuit and a time width C detection circuit that output . 8a is a shift circuit that shifts the detection pulse (FIG. 7b) output from the time width A detection circuit 7a by time (B+C); similarly, 8b is a shift circuit that shifts the detection pulse (FIG. 7) output from the time width B detection circuit 7b. This is a shift circuit that shifts C) by a time C. 9 is a majority decision circuit; this majority decision circuit 9 is.

When at least two detection pulses are detected at the timing at which the detection pulse (FIG. 7d) is output from the time width C detection circuit 7c, 1 is output from the output terminal 10. In the example shown in FIG. 7, the detection pulse (
At the timing when the signal d) in FIG. 7 is output, the shift circuit 8a
, 8b, the detected pulses (e, f in Figure T) and the detection pulse (d in Figure 7) are input, so the majority circuit 9 outputs a resector mark detection signal (g' in Figure 7). Ru.

In this way, in the conventional example, a plurality of specific time widths (A, B
, C) to detect sector marks.

Problems to be Solved by the Invention However, in the conventional example described above, there is a problem in which, for example, when a pseudo mark with the same time width as a sector mark is detected in the data section 6 in FIG. 6, it is mistakenly detected as a sector mark. there were.

The present invention solves the above conventional problems, and provides a sector mark detection device that can accurately detect sector marks without erroneously detecting them even if pseudo marks may occur. It is something.

Means for Solving the Problems In order to solve the above problems, the present invention provides a sector mark detection circuit that detects sector marks, and a window signal generation circuit that generates a window signal at predetermined intervals from the time of sector mark detection. , a pseudo mark generation circuit that generates a pseudo mark when a sector mark is not detected when a window signal is generated, and a pseudo mark counting circuit that counts the number of pseudo marks generated.

Operation The present invention has the above-described configuration, and if a mark similar to a sector mark occurs outside the window signal generation period,
This mark is not output as a sector mark,
Furthermore, even if a similar mark is erroneously output as a sector mark, once a predetermined number of pseudo marks output when a wind signal is generated is counted, a regular sector mark can be output by changing the timing at which the wind signal is generated. be.

EXAMPLE An example of the present invention will be described below. FIG. 1 shows an embodiment of the invention. In FIG. 1, 11 is a sector mark detection circuit similar to the conventional example shown in FIG. 6, and this sector mark detection circuit 11 is connected to a gate 18 that controls whether or not to output a sector mark detection signal. ing.

12 is Set Reset (SR) Flickr Frozen (FF
), and this SR, -FF 12 is set by a sector mark detection signal output from the sector mark detection circuit 11 when a sector mark is detected. 13 is S
An interval counter that generates a pulse at predetermined time intervals based on the point in time when R-FF 12 is set; 14 is a pseudo mark generation circuit;
4 generates a pseudo mark when a pulse is output from the interval counter 13. Note that when the sector mark detection circuit 11 outputs a detection signal, this pseudo mark generation circuit is prohibited from generating a pseudo mark by this pulse. A pseudo mark counting circuit 16 counts the number of generated pseudo marks. When a predetermined number of pseudo marks has been counted, the gate 18 is closed and the passage of the sector mark detection signal is blocked. 16 is interval counter 1
This is a window signal generation circuit that generates a window signal of a predetermined time width based on the pulse outputted from 3. This window signal generation circuit 16 also generates a window signal when the power is turned on or when the pseudo mark counting circuit 15 counts a predetermined number of pseudo marks.

17 is a logical sum circuit (OR circuit).

Next, the operation of this embodiment will be explained with reference to FIG.

FIG. 2a shows a part of the track of the disk in a straight line, and SM indicates a sector mark.

SM' is a pseudo mark similar to the sector mark SM in the data portion of the 0 sector (although the frequency of this mark is very low, it may occur due to scratches on the disk, etc.). In FIG. 2, when the power is turned on, the wind signal generation circuit 16
outputs 1 (FIG. 2d), and the gate 18 is in an open state. Here, when the sector mark of sector 0 is detected, a sector mark detection signal (Fig. 2b) is output, and this sector mark detection signal causes SI'L-
FF12 is set (FIG. 2C). 5R-FF12
When set, the ink counter 13 starts a time counting operation and generates a pulse when a predetermined time elapses. This pulse causes the window signal generating circuit 16 to generate a window signal (FIG. 2d). This window signal is generated at the timing when the sector mark detection signal of the next sector (one sector) is output.

Therefore, when the sector mark of one sector is detected, its detection signal (Fig. 2b) is output.During this time, the mark S
M' is detected and a sector mark detection signal is generated, but since no window signal is generated at the timing of generation of this sector mark detection signal, the detection signal is blocked by the gate 18 and is not output. As described above, according to this embodiment, even if a pseudo mark SM' is detected, this mark SM will not be erroneously detected as a sector mark.

FIG. 3 shows another operation of this embodiment. In FIG. 3, when the power is turned on and a pseudo mark SM' is detected, a detection signal (FIG. 3b) is output. The 5R-FF 12 is set by this detection signal, and the interval counter 13 starts a timing operation. After a predetermined period of time has elapsed, a window signal (FIG. 3C) is generated. A sector mark of sector 0 is detected during the period from the detection of mark 8M to the generation of the window signal, but at this time the window signal is not output, so the gate 18 is closed and the sector mark detection signal is not output. If the sector mark detection signal is not output when the window signal is generated, the pseudo mark generation circuit 14 generates a pseudo mark (FIG. 3d). Similarly second and third
Even when the second window signal is generated, the sector mark detection signal is not output and a pseudo mark is generated. A pseudo-mark counting circuit 15 counts the number of occurrences of pseudo-marks. When the pseudo mark counting circuit 15 counts a predetermined number of pseudo marks, it outputs an output signal and resets the SR-FF 12 (Fig. 3e).
), reset the window signal generation circuit 16,
The gate 18 is opened. here.

When the sector mark of 16 sectors is detected, 5R-FF1
2 is set. When the 5R-FF12 is set, the interval counter 13 performs a timing operation, and when a predetermined time elapses, a window signal (C in Figure 3) is generated, and the gate 1
8 is in the open state. While this window signal is being generated, a sector mark of 0 sector is generated and output. In this way, in this embodiment, even if the pseudo mark SM,' is erroneously detected as a sector mark, the sector mark can be detected normally thereafter.

Effects of the Invention According to the present invention, there is an advantage that a mark similar to a sector mark is not erroneously detected as a sector mark, and even when an erroneous detection is made, the normal sector mark detection operation can be immediately performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a sector mark detection device according to an embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams of the operation of the same device, FIG. 4 is a schematic explanatory diagram of an optical disc, and FIG. 6 is the same. FIG. 6 is a block diagram of a conventional sector mark detection device, and FIG. 7 is an explanatory diagram of the operation of the device. 11... Sector mark detection circuit, 12. Pathet reset flip-flop (SR-FF), 13... Interval counter, 14... Pseudo mark generation circuit, 1
5...Pseudo mark counting circuit, 16.°゛wind signal generation circuit, 17...OR circuit, 18...gate. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 4
Figure 6 Figure 7

Claims (1)

[Claims] sector mark detection means for detecting a sector mark indicating the beginning of a sector on a disk and generating a sector mark detection signal; a gate for controlling passage of the sector mark detection signal; a window signal generation means for generating a window signal for opening; a pseudo mark generation means for generating a pseudo mark when a sector mark detection signal is not output during a window signal generation period; A sector mark detecting device comprising pseudo mark counting means for causing the window signal generating means to output a window signal.