JPH05303832A - Information recording method and information reproducing method - Google Patents

Abstract

PURPOSE:To increase an information recording density. CONSTITUTION:This invention consists of the combination of two values '0' and '1'. Let d to be the minimum number of '0's which are limited natural numbers existing between '1' and '1'. In the time sequential coding information existing for the number of (d) to (k), '1' is converted to '0' only for the portion in which '0's exist for the number of (d) between '1' and '1', and among the '0's, the '0', which is located in one of the prescribed locations, is converged to '2'. This information coding is recorded onto an information recording medium in accordance with the following rules: 1) no mark is recorded at the location which corresponds to '0' on the information recording medium. 2) a mark is recorded with a first level size at the location which corresponds to '1' on the information recording medium. 3) a mark is recorded with a second level size which is larger than the first level at the location which corresponds to '2' on the information recording medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording method for recording information on an information recording medium such as an optical disk, a magneto-optical disk, a magnetic recording medium, and an information reproducing method for reproducing information from the information recording medium.

[0002]

2. Description of the Related Art Yoshikazu Ichiyama, "Recordable Optical Disk", Journal of Image Electronics, Vol. 14, No. 2, P70-76 (1985),
There is described a recording method on an optical disc medium in which a mark of equal size is formed at a position corresponding to "1" on the optical disc medium in response to input of binary information of "0" and "1".

Also, Kunimaro Tanaka "Basic Professional Basic Patent", Nikkei Electronics no. 491, P24
9-255 (1990.1.22) describes an encoding method in which input information is code-converted to include a finite natural number of "0" s between "1" s. , This coding method is a (d, k) RLL code: "Run Length in which the number of" 0 "s between" 1 "and" 1 "is dk.
(1,7) RLL as "th Limited code"
Code, (2,7) RLL code (1,3) RLL code (M
FM code) and EFM code are described.

FIG. 3 shows a recording method and a reproducing method of an optical disk (write-once optical disk, magneto-optical disk, read-only optical disk, phase change recording optical disk). First, in the recording method, the information signal is converted into (d, k) R as shown in FIG.
The information is converted into the (1,7) RLL code included in the LL code, the laser is modulated by the (1,7) RLL code, and the recording laser beam from this laser is applied to the recording medium surface of the optical disk to record information. Record on the recording medium. The temporal change in the power of the recording laser light from the laser is as shown in FIG. 3B, and the strong optical pulse 1 corresponds to the bit of "1" in the (1,7) RLL code and the recording medium of the optical disc. FIG. 3 (c) on the recording medium of the optical disc irradiated with the surface.
Marks 2 of the same size are recorded as shown in FIG.

In the reproducing method, an optical pickup scans a recording medium of an optical disk with a reproduction light spot to reproduce a signal, and a reproduction signal from the optical pickup is recorded on the optical disk as shown in FIG. The signal 3 corresponds to the presence or absence of a mark on the recording medium. The presence or absence of the mark recorded on the recording medium of the optical disc can be detected by determining whether or not the reproduction signal 3 from the optical pickup is equal to or more than an appropriate threshold value 4. Since the position of the mark recorded on the recording medium of the optical disc is the peak position of the reproduction signal 3, the reproduction signal 3 is differentiated to obtain the signal 5 as shown in FIG. 3 (e), and this signal 5 rises. At some time, it is determined whether the reproduction signal 3 is equal to or more than the threshold value 4 at the zero-cross point crossing the zero level 6 to obtain a binarized reproduction signal as shown in FIG.

[0006]

In the above-described method of recording on the optical disk medium, when the information recording density is increased by narrowing the mark intervals, the marks are overlapped to accurately determine the presence / absence of the marks. It cannot be detected, and the information recording density cannot be increased.

Further, in the above recording method and reproducing method,
Since there is only one "0" between "1" and "1", as the information recording density is increased, the reproduction signal corresponding to "0" in the "101" pattern is crushed and the mark The presence / absence determination and the mark position detection are inaccurate. The reason is that since the mark recorded on the recording medium of the optical disk has a size, the "1" part of the reproduction signal overlaps with the "0" part, or the reproduction light spot has a size of 2. This is because it is impossible to distinguish and reproduce the two marks, and inaccurate determination of the presence or absence of the mark and detection of the mark position is a phenomenon generally called a limit due to resolution.

An object of the present invention is to provide an information recording method and an information reproducing method capable of improving the above-mentioned drawbacks and increasing the information recording density.

[0009]

In order to achieve the above object, the invention according to claim 1 is an information recording method for recording information as a sequence of presence or absence of a mark on an information recording medium,
A time-series code consisting of a binary combination of “0” and “1”, in which “0” is a finite natural number between “1” and “1” and the minimum value is d to k. The information signal is converted from "1" to "0" only for a portion where "0" is present between "1" and "1", and one of the predetermined positions in "0" is converted. "0" is converted into "2", and this information signal is 1) a mark is not recorded at a position corresponding to "0" on the information recording medium, and 2) it corresponds to "1" on the information recording medium. A mark is recorded at the position at the size of the first level, and 3) A mark is recorded at the position corresponding to "2" on the information recording medium at the size of the second level larger than the first level. The information is recorded on the information recording medium according to the rule that the information is recorded. According to the invention of claim 2, in the information recording method of claim 1, d = 1 and The invention according to claim 3 is the information recording method according to claim 1, wherein d = 2, and the invention according to claim 4 is the information recording method according to claim 1, 2, or 3, wherein the information recording medium is a laser beam. An optical information recording medium for recording and reproducing information by scanning a spot, and the invention according to claim 5 is a mark on the information recording medium on which information is recorded by the information recording method according to claim 1, 2 or 3. The column is scanned by the mark detecting means to reproduce the information signal. Based on the size of the mark signal for this information signal, 1) When the mark signal is smaller than the first set value, the binary signal is set to "0", 2) When the mark signal is larger than the first set value and smaller than the second set value, the binary signal is set to "1". 3) When the mark signal is larger than the second set value, this mark signal is included. part 1), 2) to preferentially "1" and specific to "0" to d pieces present between the "1"
According to the invention of claim 6, in the information reproducing method according to claim 5, the peak appearance time of the information signal reproduced by the mark detecting means or the information signal reproduced by the mark detecting means is set in time. On the other hand, the position of the mark is detected based on the appearance time of the zero cross of the signal differentiated once.

[0010]

1 shows an embodiment of the present invention, and FIG. 4 shows a circuit used in this embodiment. In this embodiment, an information signal is subjected to code conversion so that only a pattern such as "101" having the highest mark density has a low mark density, and then an optical information recording medium such as an optical disk or a magneto-optical disk or a magnetic recording medium. Information is recorded on an information recording medium to prevent deterioration of signal quality due to the limit of resolution. In this embodiment, specifically, the information signal is converted by the RLL code converter 21 as shown in FIG.
Same as (a), (1,7) RLL as shown in FIG.
1 is converted by the ternary code converter 22 into a code.
It is converted into a time series code as shown in (b). That is,
A (1,7) RLL code as shown in FIG. 1A is sequentially checked to detect a pattern of "101", and "10" is detected.
The pattern "1" is converted into a pattern "020". Then, the laser driving circuit 23 modulates the laser of the laser recording / reproducing head 24 with this code, and the laser recording / reproducing head 24 records the recording laser light from the laser. Information is recorded on the information recording medium 25 by irradiating the recording medium 25. As the information recording medium 25, an optical disk or a magneto-optical disk is used, and a mark is recorded on a track by being driven to rotate by a spindle motor 26.

This recording rule is that 1) no mark is recorded at a position corresponding to "0" on the information recording medium 25, and 2) a mark is recorded at a position corresponding to "1" on the information recording medium 25. The recording is performed with the size of the first level, and 3) the mark is recorded with the size of the second level larger than the first level at the position corresponding to "2" on the information recording medium 25. is there.

As shown in FIGS. 1B and 1C, when the mark 7b corresponding to "2" is recorded, the power of the recording laser beam is made larger than when the mark 7a corresponding to "1" is recorded. Thereby increasing the energy of the recording laser light. The energy of the recording laser light may be increased by increasing the pulse width of the recording laser light instead of increasing the power of the recording laser light.

Further, the information recording medium 25 on which the information is recorded as described above is scanned by the laser light spot by the laser recording / reproducing head 24 constituting the mark detecting means to reproduce the signal from the information recording medium 25. As shown in FIG. 1D, the reproduction signal from the laser recording / reproducing head 24 has a high level mark signal corresponding to the mark 7b corresponding to the mark signal "2" and the mark 7a corresponding to "1".
Of the mark signal of the normal level corresponding to the mark 7 by the three-valued amplitude comparator 27 with the two threshold values 8 and 9.
The presence or absence of a and 7b is detected. In this case, the ternary amplitude comparator 27 detects the presence / absence of the mark 7a by comparing the reproduction signal from the laser recording / reproducing head 24 with the threshold value 8 and determining whether the reproduction signal is equal to or more than the threshold value 8 to detect the presence or absence of the mark 7a.
A signal with a mark as shown in FIG.
1f, the presence / absence of the mark 7b is detected by comparing the reproduction signal from the laser recording / reproducing head 24 with the threshold value 9 and determining whether the reproduction signal is equal to or more than the threshold value 9.
The mark present signal as shown in (3) is output to the AND gate 29.

Further, the reproduction signal from the laser recording / reproducing head 24 is differentiated by the differentiator 30 to obtain a signal as shown in FIG. 1 (g), and this signal is input to the zero-cross detection circuit 31 to obtain this signal. As shown by the arrow 1 (g), a zero cross point that crosses zero volts is detected at the time of rising. And
The signals from the ternary amplitude comparator 27 as shown in FIGS. 1 (e) and 1 (f) pass through the AND gates 28 and 29 at the zero cross section by the zero cross detection signal from the zero cross detection circuit 31, and the PLL clock recovery circuit 34 The clock is reproduced from the output signals of the AND gates 28 and 29.
The "101" pattern reproducing circuit 32 reproduces the code as shown in FIG. 1 (f ') from the output signal of the AND gate 29 by the clock from the PLL clock reproducing circuit 34, and the code reproducing circuit 33 reproduces the code from the PLL clock reproducing circuit 34. 1 from the output signal of the AND gate 28 by the clock of FIG.
The code as shown in (e ') is reproduced. Since the code from the AND gate 28 as shown in FIG. 1 (e ') has a pattern of "101" as compared with the original (1,7) RLL code, it is a pattern of "010". The circuit 35 receives (1,7) RLL as shown in FIG. 1 (e ') from the AND gate 28 when the code of "020" pattern as shown in FIG. 1 (f') from the AND gate 29 is not inputted. A code is taken out and outputted, and when the code of the pattern of "020" as shown in FIG. 1 (f ') is inputted from the AND gate 29, this code is outputted with priority over the code from the AND gate 28. By
The pattern of "010" is converted into the original pattern of "101" as shown in Fig. 1 (f) The code from the PLL code reproducing circuit 35 is converted by the original information reproducing circuit 36 in Fig. 1.
It is converted into the original (1,7) RLL code as shown in (h).

In this embodiment, the (1,7) RLL code is converted into only the pattern of "101" having the highest mark density into the pattern of "020" having the lowest mark density and recorded on the information recording medium 25. As shown in FIG. 1 (c), the marks 7a and 7b recorded on the information recording medium 25 are recorded with a distance of at least 3 bits, and are separated by a length of 2 bits as in the conventional case. The presence or absence of each mark and the position of each mark can be detected more accurately than in the case where the information recording density is 1.5 (3 /
2) It can be doubled.

FIG. 2 shows another embodiment of the present invention. This embodiment is an example in which the (2,7) RLL code is used instead of the (1,7) RLL code in the above embodiment. (2,7)
In the RLL code, "1001" is a pattern having the highest "1" bit density, and is a pattern in which an error occurs in recording and reproduction due to the limit of resolution.

In this embodiment, specifically, an information signal is converted by a code converter as shown in FIG.
7) Convert to an RLL code, and further convert to a time series code as shown in FIG. 2 (b) by a ternary code converter. That is, the (2,7) RLL code as shown in FIG. 2A is sequentially checked to detect the "1001" pattern,
The pattern of “1001” is converted to the pattern of “0200”. The "0200" pattern may be the "0020" pattern, but it is determined in advance as either the "0200" pattern or the "0020" pattern. And
The code from the ternary code converter is used to modulate the laser of the laser recording / reproducing head 24 by the laser driving circuit 23 in the same manner as in the above embodiment, and the laser recording / reproducing head 24 converts the recording laser light from the laser into the information recording medium 25. And the information is recorded on the information recording medium 25.

This recording rule is as follows: 1) no mark is recorded at a position corresponding to "0" on the information recording medium, and 2) a mark is first recorded at a position corresponding to "1" on the information recording medium. (3) The mark is recorded at a position corresponding to "2" on the information recording medium at a second level larger than the first level.

As shown in FIGS. 2B and 2C, when the mark 10b corresponding to "2" is recorded, the pulse width of the recording laser light is made the same as that when the mark 10a corresponding to "1" is recorded. The energy of the recording laser light is increased by increasing the power of the recording laser light. The energy of the recording laser light may be increased by increasing the pulse width of the recording laser light instead of increasing the power of the recording laser light.

Further, the information recording medium 25 on which information is recorded as described above is scanned by the laser light spot by the laser recording / reproducing head 24 to reproduce the signal. A reproduction signal from the laser recording / reproducing head 24 corresponds to a mark signal having a large level corresponding to the mark 10b corresponding to the mark signal "2" and a mark 10a corresponding to "1" as shown in FIG. 2 (d). The normal level mark signal
The presence or absence of the marks 10a and 10b is detected by the two threshold values 11 and 12 by the three-value amplitude comparator. In this case, the ternary amplitude comparator detects the presence or absence of the mark 10a by comparing the reproduction signal from the laser recording / reproducing head 24 with the threshold value 11 and determining whether or not the reproduction signal is equal to or greater than the threshold value 11, and the result shown in FIG. ) Signal with a mark as shown in
The presence or absence of the mark 10b is detected by outputting to the ND gate and comparing the reproduction signal from the laser recording / reproducing head 24 with the threshold value 12 to determine whether the reproduction signal is equal to or more than the threshold value 12, and as shown in FIG. The mark present signal as shown is output to the second AND gate.

Further, the reproduced signal from the laser recording / reproducing head 24 is differentiated by a differentiator to obtain a signal as shown in FIG. 2 (g), and this signal is input to the zero cross detection circuit and this signal is shown in FIG. As shown by the arrow in g), a zero-cross point that crosses zero-volt at the time of rising is detected. The three-valued amplitude comparator compares the output signals of the differentiator as shown in FIG.
The presence or absence of 10b may be detected. Also, the first
In the AND gate and the second AND gate, the zero-crossing detection signal from the zero-crossing detection circuit is used to pass the signals from the ternary amplitude comparator as shown in FIGS. The circuit is first
The clock is reproduced from the output signals of the AND gate of the second AND gate 29. The "1001" pattern reproduction circuit reproduces the code as shown in FIG. 2 (f ') from the output signal of the second AND gate by the clock from the PLL clock reproduction circuit, and the code reproduction circuit reproduces the clock from the PLL clock reproduction circuit. In this way, the code as shown in FIG. 2 (e ') is reproduced from the output signal of the first AND gate. The code as shown in FIG. 2 (e ') from this code reproduction circuit has a "0100" pattern in the "1001" pattern as compared with the original (2,7) RLL code. When the circuit does not input the code of the pattern "0200" as shown in FIG. 2 (f ') from the second AND gate, the circuit has (1, 1 as shown in FIG. 2 (e') from the first AND gate. 7) The RLL code is extracted and output, and the second
From the AND gate of "02" as shown in FIG.
When the code of the "00" pattern is input, this code is output by giving priority to the code from the first AND gate to output the "0100" pattern as the original "0100" as shown in FIG. 2 (f). Converted to a 1001 ″ pattern. The code from the PLL code reproducing circuit is converted into the original (2,7) RLL code as shown in FIG. 2 (h) by the original information reproducing circuit.

In this embodiment, the (2,7) RLL code is converted into only the pattern of "1001" having the highest mark density into the pattern of "0200" having the lowest mark density and recorded on the information recording medium. As shown in (c), the marks 10a and 10b recorded on the information recording medium are recorded at a distance of at least 4 bits, and are recorded at a distance of only 3 bits as in the conventional case. The presence or absence of each mark and the position of each mark can be detected more accurately than in the case where the information recording density is 1.33 (4
/ 3) It can be doubled.

The present invention is not limited to the above embodiment, and the information signal is composed of a binary combination of "0" and "1", and "1" is placed between "1". 0 "is a finite natural number, and there are d to k with a minimum value of d (d,
k) Converting to a time-series information signal of RLL code (d = 4,5,6 ...), and regarding the part where there are d "0" s between "1" and "1" of this information signal Only "1" to "0"
Converting to “2” by converting one “0” at a predetermined position in “0”, this information signal is 1) marked at the position corresponding to “0” on the information recording medium. 2) A mark is recorded at the position corresponding to "1" on the information recording medium with the size of the first level, and 3) At the position corresponding to "2" on the information recording medium. The mark may be recorded on the information recording medium according to the rule that the mark is recorded at the size of the second level which is larger than the first level.

Then, the mark train on the information recording medium on which this information is recorded is scanned by the mark detecting means to reproduce the information signal. Based on the magnitude of the mark signal, 1) the mark signal When it is smaller than the set value of 1, the binary signal is set to “0”, and 2) When the mark signal is larger than the first set value and smaller than the second set value, the binary signal is set to “1”, 3) When the mark signal is larger than the second set value, the specific pattern in which there are d "0" s between "1" and "1" in preference to the portion including the mark signal 1), 2) By doing so, the original (d, k) RLL code may be converted.

In the information recording method and the information reproducing method using such a (d, k) RLL code, the information recording density can be increased as follows in comparison with the conventional method. Value of d Ratio of information recording density to conventional method 1 3/2 times 2 4/3 times 3 5/4 times 4 6/5 times 5 7/6 times ・ ・ ・ ・ ・ ・ ・

[0026]

As described above, according to the first aspect of the present invention, there is provided an information recording method for recording information on the information recording medium as a sequence of presence / absence of marks, which is "0" or "1". Information signals of time-series codes, which consist of combinations of values and have a finite natural number "0" between "1" and "1" and a minimum value of d to k, are "1" and "1". "1" is set to "0" only for the part where there are d "0" s between
Converting to “2” by converting one “0” at a predetermined position in “0”, this information signal is 1) marked at the position corresponding to “0” on the information recording medium. 2) A mark is recorded at the position corresponding to "1" on the information recording medium with the size of the first level, and 3) At the position corresponding to "2" on the information recording medium. Since the mark is recorded on the information recording medium according to the rule that the mark is recorded at the second level larger than the first level, the information recording density can be increased as compared with the conventional method.

According to the second aspect of the invention, since d = 1 in the information recording method of the first aspect,
The information recording density can be increased to 3/2 times that of the conventional method.

According to the third aspect of the invention, since d = 2 in the information recording method of the first aspect,
The information recording density can be increased to 4/3 times that of the conventional method.

According to the invention described in claim 4,
In the information recording method described in 2 or 3, since the information recording medium is an optical information recording medium in which information is recorded / reproduced by scanning the laser light spot, the size mark of the first level and the second level are recorded. The size mark and the mark can be recorded on the information recording medium by controlling the size of the energy of the laser beam, and the positional deviation of the mark can be reduced.

According to the invention of claim 5, claim 1,
The mark detecting means scans the mark train on the information recording medium on which the information is recorded by the information recording method described in 2 or 3 to reproduce the information signal, and the information signal is reproduced based on the magnitude of the mark signal. 1) Mark When the signal is smaller than the first set value, the binary signal is set to "0". 2) When the mark signal is larger than the first set value and smaller than the second set value, the binary signal is set to "1". 3) When the mark signal is larger than the second set value, there are d "0" s between "1" and "1" in preference to the portion including this mark signal over 1) and 2). Since the specific pattern is used, the mark can be accurately reproduced from the information recording medium on which the mark is recorded by the information recording method according to the first, second or third aspect.

According to the sixth aspect of the invention, in the information reproducing method according to the fifth aspect, the peak appearance time of the information signal reproduced by the mark detecting means or the information signal reproduced by the mark detecting means is timed. Since the position of the mark is detected based on the appearance time of the zero cross of the signal differentiated once with respect to, the mark is recorded by the information recording method according to claim 1, 2 or 3 as in the invention according to claim 5. The mark can be accurately reproduced from the information recording medium.

[Brief description of drawings]

FIG. 1 is a timing chart showing an embodiment of the present invention.

FIG. 2 is a timing chart showing another embodiment of the present invention.

FIG. 3 is a timing chart showing a conventional method.

FIG. 4 is a block diagram showing a circuit used in the embodiment of FIG.

[Explanation of symbols]

 7a, 7b, 10a, 10b mark 22 three-value code converter 24 laser recording / reproducing head 25 information recording medium 27 three-value amplitude comparator 28, 29 AND gate 30 differentiator 31 zero cross detection circuit 32 “101” reproducing circuit 33 code reproducing circuit 34 PLL clock recovery circuit 35 PLL code recovery circuit

Claims (6)

[Claims] 1. An information recording method for recording information as a sequence of presence / absence of marks on an information recording medium, comprising "0" and "1".
The information signal of the time-series code, which is composed of a binary combination of 1 and 2 and has a finite natural number "0" between "1" and "1" and a minimum value of d, is "1". Only in the portion where there are d "0" s between "1" s, "1" s are converted into "0" s, and 1s at a predetermined position in "0" s are converted.
Converts two "0" s into "2", and this information signal is 1) No mark is recorded at the position corresponding to "0" on the information recording medium, and 2) Corresponding to "1" on the information recording medium. The mark is recorded at the first position with the size of the first level, and 3) The mark is recorded at the position corresponding to "2" on the information recording medium with the size of the second level which is larger than the first level. An information recording method characterized by recording on an information recording medium according to a recording rule. 2. The information recording method according to claim 1, wherein d
An information recording method, characterized in that = 1. 3. The information recording method according to claim 1, wherein d
= 2, the information recording method. 4. The information recording method according to claim 1, 2 or 3, wherein the information recording medium is an optical information recording medium for recording and reproducing information by scanning a laser beam spot. Method. 5. A mark train on an information recording medium on which information is recorded by the information recording method according to claim 1, 2 or 3 is scanned by a mark detecting means to reproduce an information signal, and a mark signal is generated for this information signal. 1) When the mark signal is smaller than the first set value, the binary signal is set to “0”, and 2) The mark signal is larger than the first set value and smaller than the second set value. Sometimes it is a binary signal "1". 3) When the mark signal is larger than the second set value, the portion including this mark signal is given priority between 1) and 2) between "1" and "1". An information reproducing method characterized in that a specific pattern in which there are d "0" s in each of the lines. 6. The information reproducing method according to claim 5, wherein a peak appearance time of the information signal reproduced by the mark detecting means or a signal obtained by differentiating the information signal reproduced by the mark detecting means once with respect to time. An information reproducing method characterized by detecting the position of the mark based on the appearance time of the zero cross.