JPH0321985B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Technical Field of the Invention The present invention provides an optical disk device, in particular, an optical disk device having a frequency different from that of an address area and a data area on an indicator area indicating sector boundaries. The present invention relates to an optical disk device in which a mark pattern of, for example, FM modulation or MFM modulation is recorded in a digital format, and a sector signal is reliably detected.

(B) Background and problems of the technology Conventionally, there have been disk-shaped recording media in which optically detectable information is recorded in a data area using a radiation beam or a radiation beam and a magnetic field, and Disk devices that utilize this are known. The recording medium is, for example, as shown in FIG.
It is configured as shown in . That is, a plurality of information tracks 2-0, 2-1, . . . are prepared on the recording medium 1, and the information tracks are arranged in a plurality of sectors 3-1, 3-2, . As shown in FIG. 1A, each sector is composed of an indicator area a, an address area b, and a data area c. Note that the above indicator area a is, so to speak, sectors 3-1, 3-2,...
It can be thought of as indicating the boundaries of..., address information such as related sectors and tracks is recorded in the address area b, and data used by the user is recorded in the data area c.

FIG. 1B shows a cut surface obtained by cutting the substrate 4 of the recording medium 1 in a direction perpendicular to the information tracks 2-0, 2-1, . . .
Track guide groove 5- with unevenness having depth of wavelength
Each information track is composed of 0, 5-1, . . . . That is, the information track 2-0 is on the track guide groove 5-0, the information track 2-1 is on the track guide groove 5-1, etc. Information is recorded by forming unevenness or pits in the direction along the respective tracks. There is.

Although it depends on the type of recording medium 1, the data area c can generally be considered as a user writing area. However, the indicator area a and the address area b may be considered to be read-only areas, and information is added in advance in a relief shape in the circumferential direction when the disk medium is manufactured. The above indicator area a, address area b, data area
When reproducing information from area c, the above information tracks 2-0 and 2-1 are
The track guide grooves 5-0, 5 in the direction along...
-1, . . . by using the depth of the groove, the laser beam is caused to travel. During this time, the information recorded as described above is read.

Conventionally, the structure is as described above, but the indicator area a indicates the boundary of each sector, and by correctly detecting the indicator area a, the following address area b and data
It is desirable to be able to reliably read the contents of area c.

(C) Object and Structure of the Invention The present invention aims to solve the above points, and provides an optical disk device in which a plurality of information tracks are each divided into a plurality of sectors, and each sector is an optical a data area in which physically detectable information can be recorded using a radiation beam or a radiation beam and a magnetic field, an address area in which address information is recorded, and the boundaries of each sector. A disk-shaped recording medium comprising at least an indicator area, wherein the indicator area and the address area have an optically detectable relief structure, and the address area has an optically detectable relief structure. Address information is recorded in a digitally encoded form similar to the data area, and the indicator area is digitally modulated at a lower frequency different from the address area and data area. mark
The device is configured to use a disk-shaped recording medium on which a pattern is recorded, and includes a detector for reading information on the recording medium, an amplifier for amplifying the signal from the detector, and a detector for detecting data in the amplified signal. a data change point detection circuit that detects a change point that passes through the level; a first timer that responds to a clock that is lower than the fundamental frequency of the information recorded in the indicator area; and a clock that operates at a fundamental frequency of the information recorded in the indicator area. a second timer that does not respond to the recording area but responds to the unrecorded area; a demodulator that demodulates information from the indicator area; and a pattern detector that detects the mark pattern on the indicator area; a counter and a gate circuit, the second timer resets the counter and the counter in the gate circuit to cause the counter to perform a count corresponding to the output of the first timer; When the pattern detector detects the mark pattern while the count value corresponding to the output is within a predetermined value range, or when the counter executes a predetermined number of counts corresponding to the output of the first timer. The feature is that the above indicators are detected in the case. are doing. This will be explained below with reference to the drawings.

(D) Embodiment of the Invention FIG. 2 is an explanatory diagram illustrating an embodiment of a disk-shaped recording medium according to the present invention, an aspect of an indicator area and a manner of detecting the indicator area, and FIG. 3 is an illustration of a disk device of the present invention. The configuration of one embodiment is shown.

In the case of the disk-shaped recording medium of the present invention, FIG.
As typically shown at the bottom of the diagram, the indicator
The fundamental frequency of recorded information in area a is set to be a different frequency, for example a lower frequency, than those in address area b and data area c. By doing so, it becomes possible to detect the fundamental frequency component in the read signal and determine the arrival of indicator area a. However, this alone is not necessarily sufficient to determine the arrival of the indicator area, and in the case of the present invention, furthermore, within each indicator area a, a specific mark indicating the area
The pattern will be recorded. and,
The arrival of indicator area a is determined by AND logic between the determination condition based on detecting the fundamental frequency component and the determination condition based on reading the mark pattern.

In the case of the present invention, instead of adopting a configuration in which the fundamental frequency component of the recorded information is extracted from the indicator area using a filter, etc., the clock frequency component of the recorded information on the indicator area is A timer that responds and a timer that responds to unrecorded areas are used.

The topmost part of FIG. 2 shows a typical manner of recording information on sectors. indicator·
On area a, there is at least an indicator mark area 6 in which an indicator mark indicating the indicator area is recorded, and gap areas 7 and 8 of a desired length exist before and after the indicator mark area 6. By decoding the content (mark) of the indicator mark area 6, it becomes information for determining that indicator area a has arrived. In address area b,
Address information such as the above-mentioned information track and sector is written, and when accessing the contents of the data area c of the sector, the presence of the indicator area a is detected, and then the address area The contents of area b are read and checked, and after confirming that it is a desired sector, user data is read/written into data area c. Data used by the user is recorded in data area c, and generally an unrecorded area 9 exists at the end of area c. This will be explained below along with the configuration shown in FIG. In FIG. 3, 10 is a photo detector that reads information from the recording medium 1;
12 is an amplifier, 12 is a data change point detection circuit, and 13 is an indicator area demodulator that performs demodulation in indicator area a (note that the information on the recording medium is recorded in the form of FM modulation or MFM modulation). 14 is the first timer according to the present invention, and 15 is the second timer according to the present invention.
16 is an indicator area pattern detector for detecting the contents of area 6 shown in FIG. 2, and 17 is a counter and gate circuit.

The first timer 14 responds to a clock frequency lower than the fundamental frequency of the recorded information in the indicator area a, but responds to a clock frequency higher than the fundamental frequency (i.e., higher frequency) of the recorded information in the address area b and data area c. It is configured so that it does not respond to Further, the second timer 15 is configured to respond to the unrecorded area 9, but not to respond to other areas. That is, the second timer 1
5 does not respond to the fundamental frequency of the indicator area, but responds to frequencies below that frequency, for example, below 1/2 of the fundamental frequency of the indicator area.
This means that it responds only to unrecorded areas that are areas below the area, address area, and data area.

If the signal d from the detector 10 is as shown in FIG. 2, the signal e passed through the amplifier 11 has a waveform as shown in FIG. 2, e. The data change point detection circuit 12 extracts the zero level passing point in the signal e and generates a pulse such as the signal f. Based on the signal f, the demodulator 13
As is conventionally known, a clock g and a demodulated signal h are output by demodulating an FM modulated signal or an MFM modulated signal.

On the other hand, the second timer 15 detects the existence of the unrecorded area 9 and notifies the counter and gate circuit 17 of the detection. Further, the first timer 14 detects the above-mentioned clock g and notifies the counter and gate circuit 17 of the detected clock g. The counter and gate circuit 17 operates as follows. That is, the second timer 1
5, it resets an internal counter (not shown) to zero. Then, in response to the signal i from the first timer 14, the contents of the counter are incremented (as shown in FIG.
reference).

The counter and gate circuit 17 notifies the pattern detector 16 of a signal k when the content of the counter reaches the value "7", for example. pattern detector 1
6 decodes the above-mentioned signal h while the signal k is at H level. If the decoding is successful, this information is output as output A. That is, the arrival of indicator area a is notified. However, in general, noise is superimposed on the signal e, and the desired mark pattern cannot be deciphered from the demodulated signal h. In this case, the above-mentioned counter in the counter and gate circuit 17 reaches a predetermined value or more, and output B is generated based on this. That is, the output B notifies that the indicator area a has arrived, as judged from the counter side, although the above-mentioned output A was not output. In this way, the detection accuracy of the indicator is significantly improved by using both the detection using the mark pattern and the gate signal (ie, output A) and the detection using only the counter (ie, output B).

In detecting the arrival of indicator area a, if only the count results from the counter and gate circuit 17 are used, the positional accuracy of detection is inferior to a method in which determination is made based on mark patterns and gate signals. However, even if some noise is mixed in, if the count value reaches a predetermined value, it can be detected as area a, so the detection error rate is lower than in the method of determining based on mark patterns and gate signals. Note that the detection by the counter, that is, the detection of only the frequency, is affected by the inclusion of noise in such a way that the clock g cannot be detected. For this reason, the introduction of noise affects the counter progress in the counter and gate circuit 17 to be delayed. If the length of the gap area 8 shown in FIG. 2 is determined in consideration of this, there will be no problem.

Furthermore, in this type of device, for example, how many sectors from the reference position on the information track the head is located is counted by a sector counter (not shown). Even if output A cannot be output normally due to noise, etc., it is possible to use output B to cause the sector counter to count correctly. Also, depending on the degree of noise contamination, even if output B is used, it may be possible to read the address area and subsequently read/write user data in the data area in the same way as when output A is used. .

(E) Effects of the Invention As explained above, according to the present invention, indicators can be detected correctly and relatively easily.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram illustrating the relationship between a disk-shaped recording medium, information tracks, sectors, and each area including an indicator area, and FIG.
FIG. 3, an explanatory diagram for explaining the area aspect and the indicator area detection aspect, shows the configuration of an embodiment of the disk device of the present invention. In the figure, 1 is a recording medium, 2 is an information track, 3 is a sector, a is an indicator area, b is an address area, c is a data area, 6 is an indicator mark area, 9 is an unrecorded area, 10
is a detector, 12 is a data change point detection circuit, 13
14 is a demodulator, 14 is a first timer, 15 is a second timer, 16 is a pattern detector, and 17 is a counter and gate circuit.

Claims (1)

[Scope of Claims] 1. A plurality of information tracks are each divided into a plurality of sectors, each sector transmitting optically detectable information using a radiation beam or using a radiation beam and a magnetic field. A disk-shaped recording medium configured to include at least a recordable data area, an address area where address information is recorded, and an indicator area that indicates the boundary of each sector, the indicator area being , the address area has an optically detectable relief structure, address information is recorded in the address area in a digitally encoded form similar to the data area, and the indicator・The area is a digitally modulated mark with a lower frequency different from the above address area and data area.
The device is configured to use a disk-shaped recording medium on which a pattern is recorded, and includes a detector for reading information on the recording medium, an amplifier for amplifying the signal from the detector, and a detector for detecting data in the amplified signal. a data change point detection circuit that detects a change point that passes through the level; a first timer that responds to a clock that is lower than the fundamental frequency of the information recorded in the indicator area; and a clock that operates at a fundamental frequency of the information recorded in the indicator area. a second timer that does not respond to the recording area but responds to the unrecorded area; a demodulator that demodulates information from the indicator area; and a pattern detector that detects the mark pattern on the indicator area; a counter and a gate circuit, the second timer resets the counter and the counter in the gate circuit to cause the counter to perform a count corresponding to the output of the first timer; When the pattern detector detects the mark pattern while the count value corresponding to the output is within a predetermined value range, or when the counter executes a predetermined number of counts corresponding to the output of the first timer. An optical disc device characterized in that the indicator is detected when the indicator is detected.