JPH03232162A - Information recording method and information reproducing method - Google Patents

Abstract

PURPOSE:To stably record and reproduce information with high information recording density and independently of a fluctuation of a recording condition and a characteristic variation of a recording medium by recording a mark of a mark signal intensity detecting part and a mark of a data recording mark part under their close positions and time. CONSTITUTION:A segment 1 is composed of at least a timing detecting mark part 2, the mark signal intensity detecting part 3 and the data recording mark part 4. A threshold for deciding whether the mark of the data recording mark part 4 is present or not is set by the mark signal intensity detecting part 3. In this case, by recording the mark of the mark signal intensity detecting part 3 and the mark of the data recording mark part 4 close to each other in space and time, a series of the marks can be recorded with approximately the same intensity. Now, the threshold for deciding the presence of the mark is set based on a signal level with the mark and a signal level without the mark in the mark signal intensity detecting part. By this method, fluctuations of the recording condition and an effect of variations in sensitivity of a recording medium can be offset to each other at the time of reproducing, and the recording and reproducing of information can be stabilized.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention can be particularly preferably used in the field of optical recording technology that records and reproduces information using laser light, and can also be applied to the field of magnetic recording technology. The present invention relates to a method and an information reproducing method.

[Conventional technology]

There are two basic techniques for reproducing recorded information, called the boundary detection method and the differential detection method, respectively.

Among these, the boundary detection method is commonly used in digital technology for compact disks and magnetic recording. However, this boundary detection method has the disadvantage that the boundary value fluctuates when recording conditions change or the type of recording film changes, making reproduction of information unstable.

The differential detection method was devised to improve the drawbacks of the boundary detection method, and the 4/15 code is known as an example thereof. In this 4715 code, 8-bit original data is converted into a 15-channel bit code according to predetermined rules. At this time, a rule was adopted in which marks were present only in 4 channel bits out of 15 channel bits, and as a result, it was possible to detect the original signal by simply comparing the amplitude levels of the reproduced signals among the 15 channel bits. Data demodulation becomes possible.

The conventional detection method using the 4/15 code will be explained below with reference to FIG.

FIG. 4(,) is a diagram showing segments on an information track in the conventional method, where 41 is a segment and the information track is composed of a chain of these segments. segment 4
1 consists of a timing detection mark section 42 and a data recording mark section 43. FIG. 4(b) is a diagram showing a specific example of marks on the segment 41, in which 50 is an information bit;
is a sequence consisting of the presence or absence of a mark corresponding to the information bit, 5
2 is a timing detection mark, and 53 is a clock generated at a timing corresponding to the mark position (including the case where there is a mark and the case where there is no mark) with the timing detection mark 52 as a starting point. The data recording marks are shown in Figure 4 (b).
), the original 8-bit data has been converted so that marks exist in only 4 channel bits out of 15 channel bits. By specifying four channel bits from among the 15 channel bits in descending order of mark signal strength, the original 8-bit information 54 is restored as shown in FIG. 4(C) using a predetermined conversion table.

[Problem to be solved by the invention]

However, in the conventional method using the 4/15 code, 15 channel bits are required for the original 8 bits of information, resulting in increased redundancy, making it impossible to achieve high information recording density, and requiring a high clock frequency for playback. The disadvantage was that the circuit was also expensive.

The present invention eliminates the drawbacks of the prior art and provides an information recording method and an information reproducing method that have a high information recording density and can stably record and reproduce information regardless of fluctuations in recording conditions or characteristics of recording media. The purpose is to

[Means to solve the problem]

According to the present invention, in order to achieve the above object, marks are selectively recorded at positions having a predetermined interval along an information track of an information recording medium, and information is expressed by the presence or absence of marks at each of the positions. The information recording method includes at least a timing detection mark section serving as a starting point for generating a timing block corresponding to each position, a mark signal strength detection section for setting a threshold value for determining the presence or absence of a mark, and a data recording mark section. An information recording method is provided, characterized in that the configured segment is recorded as the minimum unit, and the mark of the mark signal strength detection section and the mark of the data recording mark section are recorded at close positions and times by the same recording means. Ru.

Also. According to the present invention, the means for detecting recording marks is scanned at a constant speed along the information track of the information recording medium recorded by the above method, and while performing the operation of detecting the recording marks in chronological order, Timing detection From the time when the mark is detected, a signal corresponding to the mark intensity is detected at a time interval corresponding to the mark interval, and the signal level with mark and the signal level without mark in the mark signal strength detection section is used as a reference. Accordingly, there is provided an information reproducing method characterized in that information is reproduced by determining the presence or absence of a series of marks in a data recording mark portion.

[For production]

In the present invention, a mark signal strength detection section is provided in the segment, and a threshold value for mark presence/absence determination is set based on the marked signal level and the no mark signal level in the mark signal strength detection section. Since it changes uniformly with the same tendency as fluctuations and variations in characteristics of the recording medium, reading errors can be minimized and recording density can be improved.

〔Example〕

The present invention will be described in detail below based on examples.

FIG. 1(a) is a diagram showing segments on an information track of an information recording medium to which the method of the present invention is applied.

1 is a segment, and an information track is composed of a chain of segments, which can take the form of a spiral,
Concentric circles, parallel shapes, etc. are selected as appropriate.

The segment 1 includes at least a timing detection mark section 2, a mark signal strength detection section 3, and a data recording mark section 4. FIG. 1(b) is a diagram showing a specific example of a mark on segment 1, in which 10 is an information bit;
1 is a column consisting of the presence or absence of a mark corresponding to the information bit;
12 is a timing detection mark, and 13 is a clock.

Timing detection mark section 2 is timing detection mark 12
The mark position (including cases with a mark and cases without a mark) with the timing detection mark 12 as a starting point
are arranged at predetermined intervals.

In this way, it becomes possible to easily detect and determine whether or not there is a mark at a predetermined position. - In general, an information track and a means for detecting marks on the information track (such as an optical pickup or a magnetic recording head) move at a constant speed relative to each other, thereby converting mark position information into time information and transmitting information. In a recording and reproducing apparatus that records and reproduces data, the mark position and the timing of the recording and reproduction signal have a 1=1 correspondence. Therefore, by generating the clock 13 at predetermined time intervals based on the timing detection mark 12, accurate synchronization with the mark position can be achieved, and the presence or absence of the mark can be determined based on the strength of the signal level at that time. Playback becomes possible.

The mark signal strength detection section 3 is for setting a threshold value for determining the presence or absence of a mark in the data recording mark section 4. The mark of the mark signal strength detection section 3 is the data recording mark section 4.
For this purpose, it is preferable that the mark be recorded under basically the same conditions as the mark.

It is effective to record in close proximity both spatially and temporally. For example, when recording marks with a laser beam on an optical disk, it is preferable that the influence of fluctuations in laser output, defocus, and sensitivity differences and unevenness of the recording medium be small, and the mark signals should be close to each other both spatially and temporally. When the mark of the intensity detection part 3 and the mark of the data recording mark part 4 are recorded,
A series of marks can be recorded with approximately the same intensity.

Here, the pattern of the mark signal strength detection section 3 is known, and it is possible to know in advance in which positions there are marks and in which positions there are no marks.

Detecting a signal level with a mark and a signal level without a mark in at least one pair, and finding an intermediate value between the two,
This may be set as a threshold value for determining the presence or absence of a mark, and the presence or absence of a mark in the data recording mark section 4 may be determined. When reproducing in this way, the mark signal strength detection section 3 and data recording mark section 4 change uniformly with the same tendency even if the mark signal strength changes, so even under actual use conditions, the mark signal strength detection section 3 and data recording mark section 4 are always at the optimum level. A threshold value for the presence or absence of a mark is set according to the conditions, and reading errors can always be minimized.

Note that the patterns of the mark signal strength detection section 3 do not always have to be the same, and two types of patterns may be prepared, one in which the presence or absence of marks is reversed and one without. In this way, in the case of an inverted pattern, the pattern of the data recording mark section 4 can also represent that the presence or absence of a mark is inverted.

In the case of optical discs, the more marks there are in the data recording mark area, the longer the laser beam is emitted strongly during recording, which makes the semiconductor laser more likely to deteriorate.
By inverting and recording the original data, such inconveniences can be prevented from occurring. Of course, since the presence or absence of reversal can be detected during playback, the original information can be restored. That is, the pattern in the mark signal strength detection section 4 can be adjusted within a range that allows detection of the signal strength of the presence or absence of a mark, and it is also possible to express information thereby.

(a) in FIG. 1(c) shows the waveform of the segment portion recorded and reproduced by the above method, and the timing detection mark 12
When the peak 14 corresponding to 14 is detected, a clock is started at predetermined time intervals starting from that time as shown in (b), and this clock increases the mark signal strength at the timing corresponding to the mark position in the reproduced waveform. A threshold value for mark presence/absence determination is set based on the signal level with mark and the signal level without mark in the mark signal strength detection section 3, and based on that, the data recording mark section 4
The presence or absence of the mark is determined, and the original bit information is reproduced as shown in (c).

In practice, the timing detection mark section 2 is 1 byte, the mark signal strength detection section 3 is 1 byte, and the data recording mark section 4 is 1 byte.
It is also possible to make it around 15 bytes, so in that case,
It is sufficient to add extra information at a ratio of 2/15 to the actual data, and high-density recording can be achieved.

Next, a specific example of the information reproducing method according to the present invention will be explained with reference to FIG. FIG. 2 is a block diagram showing an example of the configuration of a reproducing apparatus for implementing the information reproducing method according to the present invention, in which a timing mark detection circuit 21, a clock generator 22
, sample and hold circuits 23 and 24, a clock counter 25, a comparator 26, and a data reproduction circuit 27.

To explain the reproduction operation, reference numeral 20 denotes a reproduction signal waveform reproduced from an information track of an information recording medium recorded by the recording method explained in FIG. The detection mark (12 in FIG. 1) is detected. The clock generator 22 generates clocks at predetermined intervals starting from the time when the timing detection circuit 21 detects the timing detection mark, and supplies the clocks to the clock counter 25 and the data reproduction circuit 27 . The clock counter 25 counts the input clock, generates a pulse at a timing corresponding to the mark position □ of the mark signal strength detection section (3 in FIG. 1), and activates the sample and hold circuits 23 and 24. One of the sample and hold circuits 23 and 24 samples and holds the reproduced signal waveform at a timing with a mark, and the other one at a timing without a mark. Then, an intermediate level between the marked signal and the unmarked signal is supplied as a threshold to one input terminal of the comparator 26, and the reproduced signal waveform 2o is supplied to the other input terminal of the comparator 26. Comparator 26 compares these two,
Determine the presence or absence of a mark. The data reproducing circuit 27 receives the clock from the clock generator 22 and the mark presence/absence identification result from the comparator 26, identifies whether there is a mark at a predetermined time, and reproduces the original data 28.

Furthermore, according to the present invention, it is also possible to reproduce information using a reproduction device mainly composed of digital circuits, as shown in FIG. In this case, the timing mark detection circuit 21 detects a timing detection mark based on the reproduced signal waveform 2o, and the clock generator 22 generates a clock at a predetermined time interval based on the detected time, and the reproduced signal waveform 20 is /D conversion (analog/digital conversion)
The digital data reproducing circuit 31 then uses the same method as described above to identify the presence or absence of a mark in the data recording mark portion, thereby obtaining the original data 28.

Although specific examples of the present invention have been described above, the present invention is not limited to these examples only, and various modifications and changes are possible. In addition to optical recording media, it is also applicable to magnetic recording media.

〔Effect of the invention〕

According to the first aspect of the invention, it becomes possible to record information in a form in which the effects of fluctuations in recording conditions when recording marks and variations in sensitivity of recording media can be offset during reproduction.

■It is now possible to record information with high density.

Memory costs can be reduced.

According to the invention as claimed in claim 2, the information recording medium recorded by the method as claimed in claim 1 is free from errors regardless of fluctuations in recording conditions when recording marks and variations in sensitivity of the recording medium. It becomes possible to reproduce information in a small amount and reliably.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the present invention in detail, FIG. 2 is a block diagram showing the circuit configuration of a remaster device for implementing information reproduction according to the present invention, and FIG. FIG. 4 is a block diagram of a case where the system is mainly composed of digital circuits, and is an explanatory diagram of the conventional detection method using the 4/15 code. 1...Segment 2...Timing detection mark section 3...Mark signal strength detection section 4...Data recording mark section 10...Information bit 11...Sequence 12 consisting of mark presence/absence... Timing detection mark 13...clock

Claims (2)

[Claims] (1) An information recording method in which marks are selectively recorded at positions having predetermined intervals along an information track of an information recording medium, and information is expressed by the presence or absence of marks at each of the positions, at least at each of the positions. A segment consisting of a timing detection mark section having a timing detection mark that serves as a starting point for generating a clock at a timing corresponding to the timing, a mark signal strength detection section for setting a threshold for mark presence/absence determination, and a data recording mark section. An information recording method characterized in that the mark of the mark signal strength detection section and the mark of the data recording mark section are recorded at close positions and times by the same recording means. (2) While scanning the recording mark detecting means at a constant speed along the information track of the information recording medium recorded by the method of claim 1, and performing an operation of detecting the recording marks in chronological order, Timing detection From the time when the mark is detected, a signal corresponding to the mark intensity is detected at a time interval corresponding to the mark interval, and the signal level with mark and the signal level without mark in the mark signal strength detection section is used as a reference. An information reproducing method characterized in that information is reproduced by determining the presence or absence of a series of marks in a data recording mark portion.