JPS63166073A - Detecting device for sector mark - Google Patents

Abstract

PURPOSE:To accurately detect a sector mark without detecting a pseudo mark as the sector mark erroneously even when it is generated, by preventing the pseudo mark from being outputted as the sector mark even when the pseudo mark is detected among the sector marks. CONSTITUTION:When the sector mark and the sector mark detecting signal of a sector 0 is outputted from a sector mark detection circuit 11, a set/reset flip-flop (SR.FF)13 is set, and an interval counter 14 starts a clock operation, and generates a pulse after the lapse of a prescribed time. A window signal generation circuit 16 generates a window signal at a timing when the sector mark detecting signal of the next sector 1 is outputted based on the pulse. Also, a pseudo mark generation circuit 15 generates the pseudo mark based on the pulse, however, the detecting signal is blocked by a gate 12 and is not outputted even when the detecting signal is outputted from the sector mark detection circuit 11, because no window signal is generated at this timing. In such way, the mark resembled to the sector mark is not detected as the sector mark erroneously.

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 3 shows a recording disk (disk) used in an optical disk device.
It shows. In FIG. 3, 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. 3 shows an example in which one track is composed of eight sectors. Black dots 2 in FIG. 3 indicate sector marks placed at the beginning of each sector.

FIG. 4 shows a conventional sector format. In FIG. 4, 3 is a sector mark (SM), 4 is an ID section for recording addresses, etc., and 6 is a data section. Figure e a
shows an example of a sector mark (SM), which is the 0 part of time width A and the 1 part of time width B.
part, consisting of 0 part of time width C.

FIG. 6 shows a sector mark detection circuit for detecting the sector mark shown in FIG. 6a. In FIG. 6, 6 is an input terminal to which a signal picked up from the disk 1 is applied, and 7a is a time width A detection circuit. 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 6b) is output. Similarly, 7b and 7c are detection pulses when time widths B and 0 are detected, respectively (Fig. 6 c, 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. 6b) output from the time width A detection circuit 7a by time (B+0); similarly, 8b is a shift circuit that shifts the detection pulse (FIG. 6) output from the time width B detection circuit 7b. This is a shift circuit that shifts C) by a time C. Reference numeral 9 denotes a majority decision circuit, and this majority decision circuit 9 outputs a signal from the output terminal 10 when at least two detection pulses are detected at the timing at which the detection pulse (Fig. 6 d) is output from the time @C detection circuit 7c. Outputs 1. In the example shown in FIG. 6, the shift circuit 8a,
Since the detected pulses (e, f in Figure 6) and the detected pulses (d in Figure 6) shifted at 8b are input, the majority circuit 9
A resector mark detection signal (Fig. 6g) is output.

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, for example, when a pseudo mark with the same time width as a sector mark is detected in the data section 6 in FIG. 4, there is a problem that it is mistakenly detected as a sector mark. there were.

The present invention solves the above-mentioned conventional problems, and provides a sector mark detection device that can accurately detect sector marks without erroneously detecting them even if pseudo marks are generated.

Means for Solving the Problems In order to achieve the above object, the present invention includes: a sector mark detection circuit that detects sector marks; 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 is provided which generates a pseudo mark when a sector mark detection signal is not output when a window signal is generated.

Operation The present invention has the above configuration, and even if a pseudo mark is detected between sector marks, this mark will not be output as a sector mark.An embodiment of the present invention will be described below. Let's discuss an example. 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. 5, and this sector mark detection circuit 11 is connected to a gate 12 that controls whether or not to output a sector mark detection signal. ing.

13 is a set reset (SR) flip-flop (FF
), and this 5R-FF'13 is set by a sector mark detection signal output from the sector mark detection circuit 11 when a sector mark is detected. 14 is 5
An interval counter that generates a pulse after a predetermined time from the point in time when the R-FF 13 is set as a reference, 15 is a pseudo mark generation circuit, and this pseudo mark generation circuit 16
generates a pseudo mark when a pulse is output from the interval counter 14. Note that when the sector mark detection circuit 11 outputs a detection signal, the pseudo mark generation circuit 16 is prohibited from generating a pseudo mark by this pulse. 16 is a window signal generation circuit that generates a window signal of a predetermined time width based on the pulse output from the interval counter 14. The gate 12 is opened by the output of the window signal generating circuit 16. 1
7 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 the sector mark S included in the data part of the sector.
This is a pseudo mark similar to M (this mark occurs very rarely, but may be caused by scratches on the disc, etc.). In Fig. 2, when the power is turned on, the window signal generating circuit 1e outputs 1 (Fig. 2d), and the gate 1
2 is in the open state. Here, when the sector mark of sector 0 is detected first, the sector mark detection signal (second
(b) in FIG. 2 is output, and SR.F'F13 is set by this sector mark detection signal (FIG. 2C).

When the 5R-FF 13 is set, the interval counter 14 starts a timing 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, the detection signal (Fig. 2b)
) is output. During this time, the mark (SM) 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 12 and is not output. In this way, according to this embodiment, a pseudo mark (
Even if SM') is detected, this mark (SM) will not be erroneously detected as a sector mark.

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.

[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, FIG. 2 is an explanatory diagram of the operation of the same device, FIG. 3 is a schematic explanatory diagram of an optical disc, and FIG. FIG. 5 is a block diagram of a conventional sector mark detection device, and FIG. 6 is an explanatory diagram of the operation of the same device. 11... Sector mark detection circuit, 12... Gate,
13...Set-reset flip-flop (SR-F
F), 14° interval counter, 15... pseudo mark generation circuit, 16... window signal generation circuit, 1
7...OR circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Figure 4

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 sector mark detection device comprising: window signal generation means for generating a window signal for opening; and pseudo mark generation means for generating a pseudo mark when a sector mark detection signal is not output during a window signal generation period.