JPH0869626A - Digital modulation and demodulation method, device thereof, recording medium and its production - Google Patents

Abstract

PURPOSE: To improve an information density by converting digital data of m-bits to n(n>m) bit conversion codes by using a conversion table and inserting the required coupling bit between the continuous two blocks. CONSTITUTION: The data of 10-bits, etc., are converted to block data of 15-bits by a ROM 10 of a conversion table and these sets of the data are successively stored in registers 14, 12. A coupling bit processing section 2 determines the coupling bit of both blocks and code converts the pits of the blocks before and behind this bit according to need in accordance with the post number bits of the block before the register 14 and the fore number bits of the block behind the register 14. The light from a light source 38 is then subjected to light intensity modulation by an optical deflector 40. The 15-bit conversion data of the two blocks processed by a coupling bit processing section 23 is joined by the required joining bit and the signal subjected to the intensity modulation by the deflector 41 is deflected. The data are recorded in the track direction and the direction perpendicular thereto, by which the information density is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital modulation / demodulation system for converting m-bit digital data and n-bit digital data, and more specifically, information on presence / absence of pits and displacement is provided. The present invention relates to a digital modulation / demodulation method, a device therefor, a recording medium, and a method for manufacturing the same, which are suitable for high-density information recording and transmission using the included recording method.

[0002]

BACKGROUND ART When digital data is recorded on a medium or transmitted using a communication path, data code conversion (so-called channel coding) is usually performed so as to match the characteristics of those recording systems and transmission systems. Is done. Various types of modulation schemes for such encoding are already known. For example, Japanese Patent Laid-Open No. 57-132461, Japanese Patent Laid-Open No. 58-220212, and Japanese Patent Publication No. 4-77991. Is disclosed in. Hereinafter, they will be described in order.

(1) Japanese Unexamined Patent Publication No. 57-132461 This publication discloses a binary data code conversion device in which parameters (d, k, m, n) of a modulation method are (2, 10, In 8 and 17), the 8-bit digital data is converted into 17-bit digital data including 3 combined bits. EFM (Eight to Fourteen
Modulation, 8/14 modulation), CD
This is the modulation method used in the system.

The meanings of the parameters are as follows. d (minimum run): minimum inversion interval (minimum length bet
ween transition) Represents the minimum number of logical values "0" contained in Tmin. When d = 2, at least two “0” s are included between the logical values “1” and “1”. k (maximum run): maximum inversion interval (maximum length bet
ween transition) Represents the maximum number of logical values "0" contained in Tmax. When k = 10, the maximum number of “0” s included between the logical values “1” and “1” is 10. m: represents the number of bits of digital data before conversion. n: represents the number of bits of the digital data after conversion. According to this background art, the recording density ratio is DR (Density Ra
tio) = (d + 1) × m / n = 1.41.

(2) Japanese Patent Laid-Open No. 58-220212 In the digital modulation method disclosed in this publication, the parameters (d, k, m, n) are (2, 8, 4, 8), respectively.
Then, 4-bit digital data is converted into 8-bit digital data. In this 4/8 modulation method, the recording density ratio is DR = 1.5.

(3) Japanese Patent Publication No. 4-77991 In the digital modulation method disclosed in this publication, the parameters (d, k, m, n) are (1, 8, 8, 14), respectively.
Then, 8-bit digital data is converted into 14-bit digital data. In this 8/14 modulation method, the recording density ratio is DR = 1.14, and the DSV (Digi
tal Sum Value) controllable conversion table is used.

[0007]

By the way, among the background arts described above, DR = 1.4 in the EFM method.
1, the DR is 1.5 in the 4/8 modulation method, which is larger than the EFM method in the DR, and is a method capable of increasing the information density. However, recently, recording / reproducing and transmission of higher density information have been demanded, and a larger DR modulation system has been demanded.

On the other hand, Japanese Patent Laid-Open No. 4-74317 discloses an optical system in which information is placed both on the presence or absence of pits in the track direction on a recording medium and on the minute displacement of the pits in the direction orthogonal to the track. A recording / reproducing system is disclosed. According to this, it is possible to substantially increase the recording density by 1.5 times as compared with the conventional binary recording method only using the presence or absence of pits. Therefore, using this method,
Higher density information recording and reproduction can be expected.

The present invention focuses on such a point, and its object is to improve the information density in recording, reproduction and transmission.

[0010]

In order to achieve the above object, according to the present invention, first, information on the presence or absence of a bit in the track direction on a recording medium and the displacement of a minute amount of the bit in the direction orthogonal to the track is provided. An optical recording method of mounting the optical disk is prepared. Then, the m-bit digital data is converted into n-bit digital modulation data using a conversion table that is predetermined so as to satisfy the desired inversion interval condition and the pit / land connection condition. Thereby, a large DR can be realized. For example, when the modulation method in which the parameters (d, k, m, n) are (2, 13, 10, 16) is adopted, DR = 1.88 and 4 /
It is 1.25 times that of the 8 modulation method. That is, the linear recording density is increased by 25%.

The main aspects of the present invention are as follows. (1) A digital modulation method characterized by converting m-bit digital data into n-bit digital modulation data using a modulation method having first and second code forming means. (2) Using the code forming means of the above (1), m-bit digital data n-
A conversion table conversion method for converting p-bit digital modulation data, wherein a plurality of tables are used so that modulation data can be combined by combining bits.

(3) A method of limiting the minimum inversion interval and the maximum inversion interval of digital modulation data, which uses the modulation code and the combination bit of the above (1) and (2). (4) The digital modulation method according to (1), wherein the method of limiting the minimum inversion interval and the maximum inversion interval of (3) is used. (5) A DSV control method characterized in that the conversion table of (2) is used to control the DSV value of the modulation data combined by the combined bits to V (V ≠ 0).

(6) By using the conversion table of (2), the DSV value of the modulated data combined by the combined bits is
A method of controlling a DSV, characterized by controlling to an average value of CDS of all modulation codes on a table. (7) The digital modulation method according to (1), characterized in that the DSV control method according to (5) or (6) above is used. (8) A method of constructing a conversion table, wherein a part of the conversion table of (2) is divided in order to realize the DSV control method of (6).

(9) Digital modulation according to (1), characterized in that m-bit digital data is converted into n-bit digital modulation data by the conversion table constructed by the methods (2) and (8). Method. (10) In the conversion table of (8) above, m = 10.
When n = 16 · p = 1 and the number of "0" at the beginning and end of each modulated data is within 8 consecutive, the pattern including 11 "0" s between "1" and "1" (1) The digital modulation method according to (1), wherein the synchronization pattern is used.

(11) The above (1), (4), (7), (9),
Alternatively, a digital recording device for recording digital information by the digital modulation method described in (10). (12) A recording medium on which digital information is recorded by the digital recording device according to (11). (13) A digital reproducing apparatus characterized by reading digital information from the recording medium according to (12) above and performing a reproducing process opposite to the recording process in the digital recording device according to (11) above. The above and other objects, features and advantages of the present invention will be apparent from the following detailed description and the accompanying drawings.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS While there may be many embodiments of the present invention, a suitable number of embodiments will now be shown and described in detail.

<Modulation Processing Method> First, the modulation processing method of the embodiment will be described with reference to FIGS.
Note that the case of converting 10-bit data into 16 channel bits will be described as an example.

First, for example, the codes are defined as follows: (1) Code 0: No change, pit or land continues. (2) Code 1: Indicates the change from pit to land. (3) Code a: Indicates a change from land to pit. However, it is a change to a pit that has no displacement in the direction orthogonal to the track with respect to the previous pit. (4) Symbol b: Similarly, it represents a change from land to pit. However, it is a change to a pit having a displacement in the track orthogonal direction with respect to the previous pit. It is also used for displacement in the middle of the pit.

Of these, codes 0 and 1 are used for forming the first code corresponding to the presence or absence of pits in the track direction, and for forming the second code corresponding to the displacement of pits in the track orthogonal direction. The symbols a and b are used.

Next, using such a code, a table of a 15-bit modulation code in which (d, k) becomes (2,10) is created. Here, if 1 or more combined bits are used and more than 1024 modulation codes can be prepared in the table, conversion between 10-bit digital data and 16-bit digital data becomes possible.

However, in this embodiment, the data is multiplexed by giving the displacement in the track orthogonal direction only to the pits.
Therefore, as in the background arts (1) to (3), the pits and lands are undefined, that is, the correspondence between the data sign (logical value 1, 0) and the pits / lands cannot be set arbitrarily. No, you must always specify the relationship between the code and the pit land. If there is such a limitation, the modulation code cannot be freely combined with one combined bit, and the conditions described below are required. However, the combined bit shall be a logical value of "0" except in special cases described later.

(1) When the code at the end of the modulation code before the combined bit is "0" and is a pit For example, in the example shown in FIG. 1A, the modulation code before the combined bit mb is "a00100b00100a00". ", And the code at the end is" 0 ". Then, as shown in FIG. 7B, the end code "0" is a pit. In such a case, the beginning of the subsequent modulation code must be a pit of "0" or a land of "1", and other modulation codes cannot be combined. The same figure (A), (B) is an example of the pit of "0", and the modulation code after the combined bit mb is "00100b00b000100".
Has become. (C) and (D) of the figure are examples of the land of "1", and the modulation code after the combined bit mb is "100b000b".
It is 0001000 ”.

Since the combination bit mb is set to "0" except in a special case, the modulation code of the land whose start is "0" and the pit of "1" cannot be combined. In these cases, the connection bit mb must be set to "1" because of the relationship between the land and the pit.

(2) When the end code of the modulation code before the combined bit is a land of "0" For example, in the example shown in FIG. 2A, the modulation code before the combined bit mb is "100a00100b00100". And the code at the end is "0". Then, as shown in FIG. 7B, the last code "0" is a land. In such a case, the beginning of the subsequent modulation code must be a "0" land, an "a" pit, or a "b" pit. The same figure (A), (B)
Is an example of a land of "0", and the modulation code after the combined bit mb is "00a00b000100b00". (C) and (D) of the figure are examples of the pit of "a", and the modulation code after the combined bit mb is "a00100a000b0001". The combined bit mb is "0" except in special cases.
Therefore, the modulation code of the pit whose start is "0" cannot be combined.

(3) When the end code of the modulation code before the combined bit is a pit of "a" For example, in the example shown in FIG. 3A, the modulation code before the combined bit mb is "00a00100b00100a". And the code at the end is "a". Then, as shown in FIG. 7B, the final symbol "a" is a pit. In such a case, the beginning of the modulation code that follows must be a "0" pit, an "a" pit, or a "b" pit. The figure (A), (B) is "0"
The example of the pit of "b" is shown in FIGS. 7 (C) and (D).

However, when the end code of the preceding modulation code is the pit of "a" and the start code of the subsequent modulation code is the pit of "a" or "b", the combined bit mb is "0". Then, the condition of the minimum run d = 2 cannot be satisfied. Therefore, as indicated by the arrows in FIGS. 6E and 6F, the combined bit mb is set to the code at the beginning of the subsequent modulation code, that is, "a" or "b", and the codes before and after it are set to " I will convert it to 0 ". As a result, the condition of the minimum inversion interval Tmin is satisfied.

However, in this way, the code information "a" at the end of the previous modulation code disappears, and "a"
Or it becomes impossible to distinguish "b". Therefore, the use of "b" as the code at the end of the modulation code is prohibited.

(4) When the end code of the modulation data before the combined bit is a land of "1" For example, in the example shown in FIG. 4A, the modulation code before the combined bit mb is "00100a00100b001". And the code at the end is "1". Then, as shown in FIG. 7B, the last code "1" is a land. In such cases, the beginning of the modulation code that follows must be a "0" or "1" land.
(A) and (B) of the figure are examples of the land of "0", and (C) and (D) of the figure are examples of the land of "1".

However, as in the examples shown in (C) and (D) of the same figure, the code at the end of the preceding modulation code is a land of "1", and the start of the subsequent modulation code is also "1". In the case of the land, if the combined bit mb is "0", d = 2
The condition of will not be satisfied. Therefore, as indicated by the arrows in FIGS. 7E and 7F, the combined bit mb is set to "1", and the codes before and after it are converted to "0".

(5) When the end of the modulation code before the combined bit is two or more "0" pits, and the subsequent modulation code starts after it is five or more "0" pits. In the example shown in FIG. 5 (A), the modulation code before the combined bit mb is “0000a0001000b00”, and the last two codes are “0”. Then, as shown in FIG. 7B, the code "0" at the end of them is a pit. Further, as shown in (A) of the same figure, the modulation code after the combined bit mb is "000001000b00100".
And the five signs at the beginning are "0". Then, as shown in FIG. 3B, the code "0" at the beginning of them is a pit.

In such a case, the maximum inversion interval Tmax
(Or the maximum run k), the combined bit mb is set to "1" as shown by the arrows in FIGS. 7C and 7D, and the subsequent modulation is performed to further determine it. The 3rd bit from the beginning of the code will be converted to "a".

(6) In the case where the end of the modulation code before the combined bit is two or more "0" lands, and the subsequent modulation code starts after five or more "0" lands. In the example shown in FIG. 6 (A), the modulation code before the combined bit mb is “00001000b000100”, and the last two codes are “0”. Then, as shown in FIG. 7B, the code "0" at the end of them is a land. Further, as shown in (A) of the figure, the modulation code after the combined bit mb is "00000a000010000".
And the five signs at the beginning are "0". Then, as shown in FIG. 3B, the code "0" at the beginning of them is a land.

In such a case, the maximum inversion interval Tmax
(Or the maximum run k), the combined bit mb is set to "a" as shown by the arrows in (C) and (D) of FIG. The 3rd bit from the beginning of the code will be converted to "1".

<Conversion table> Conditions for the above inversion intervals,
When the conversion table is constructed in consideration of the connection condition of pits and land, it becomes as shown in Table 1 below.

[0035]

[Table 1]

In Table 1, the data is displayed in decimal. On the other hand, the pits and lands at the beginning of the modulation code and the corresponding codes are determined by the four sets of conversion tables 1 to 4 corresponding to the pits and lands at the end of the modulation code and the codes.

Reexpressing this as shown in Table 2 below,
It can consist of two sets of conversion tables, a pit table and a land table. However, in these two sets of conversion tables, the modulation codes before and after must be in one-to-one correspondence. Further, these two sets of conversion tables can be combined with only one of them, rather than selecting whichever one has better conditions. In other words, the land table cannot be used when the pit table is used, and conversely, the pit table cannot be used when the land table is used.

[0038]

[Table 2]

By the way, in the modulation method according to this embodiment, since the data is multiplexed only in the pits, the CDS (Code Word Digital) of the modulation code on the conversion table is multiplexed.
Sum) will inevitably become larger than “0” and DSV
Cannot be controlled to "0". Therefore, assuming that the servo system of the recording device and the auto slice circuit of the reproducing device are operated with an offset,
The conversion table is configured so that the DSV is controlled to a predetermined value “V” that is not “0”.

First, letting V be the average value of the CDS of all the modulation codes on the conversion table of Table 2, a part of the table is further divided into two as shown in Table 3 below, and one of them is the CDS.
The modulation code of <V and the modulation code of CDS> V are arranged on the other side. Then, any one of them has a predetermined value V
The value of DSV is controlled to V by selectively using the one that approaches. As a result, as shown in Table 3, the conversion table shows that pits and lands each have a DSV.
<, DSV> V will be 4 sets.

[0041]

[Table 3]

In addition to these, the following two conditions are further provided in this embodiment. (1) In order to limit the maximum inversion interval Tmax, the number of consecutive 0s at the beginning and end of each modulation code is limited to eight.

(2) Considering the feasibility of cutting the disc, the displacement in the middle of the pit is used for 7T pits (a or b is a code in which six 0s follow),
It is expressed as follows. 7T pit: "a00b000" or "b00b000" 8T pit: "a000b000" or "b000b000" 9T pit: "a000b0000" or "b000b0000" 10T pit: "a0000b0000" or "b0000b0000" 11T pit: "a0000b00000" or "b0000b00000"

When the conversion table of the parameters (d, k, m, n) = (2, 13, 10, 16) is actually constructed based on the above conditions, the following table 4 is obtained. However, as a result of the limitation of the maximum inversion interval Tmax described above, k = 1.
It is 3.

[0045]

[Table 4]

Table 5 shows a part of the actual conversion code table obtained based on the conversion table of Table 4.

[0047]

[Table 5]

<Modulation Device, Disk Manufacturing Device> Next, a modulation device and a disk manufacturing device using the same will be described with reference to the block diagram of FIG.

The 10-bit data is converted into conversion ROMs 10 and 1.
1 is input, and 10-bit data is
Converted to channel bit modulation code. However, RO
M10 is a conversion table corresponding to the modulation of the presence or absence of pits in the track direction, and more specifically, it is a conversion table to the modulation code where a = b → 1 in Table 4 above. Further, the ROM 11 is a conversion table corresponding to modulation of pit displacement in the track orthogonal direction,
Specifically, in Table 4, 1 → 0, a → 0, b → 1
Is a conversion table to the modulation code.

The modulation code after conversion by the ROM 10 is
Registers 12 and 1 are transferred to registers 12 and 14 in order.
The data of 4 blocks before and after is stored in 4 respectively. The modulation code converted by the ROM 11 is sequentially transferred to the registers 13 and 15, and the registers 13 and 15 store the data of the two blocks before and after, respectively. The data stored in the registers 14 and 15 are supplied to the selectors 18 and 19 together with the code of the frame synchronization pattern output from the synchronization code output unit 16, where predetermined selection is performed and stored in the memories 20 and 21. It

As the frame synchronization pattern, a pattern that does not exist in the modulation code pattern is used. For example, “0” is the maximum run between “1” and “1” k +
A pattern that includes one is a synchronization pattern.

Next, the rear few bits of the previous modulation code block stored in the register 12 and the front few bits of the modulation code block after stored in the register 14 are referred to by the combined bit processing unit 22. The above-described code connection is determined, the combined bit is provisionally determined, and the code conversion before and after that is performed if necessary. Similarly, the rear few bits of the previous modulation code block stored in the register 13 and the front few bits of the modulation code block after stored in the register 15 are referred to by the combined bit processing unit 23 and described above. Is determined to temporarily determine the combined bit, and if necessary, code conversion before and after that is performed.

At this time, when the logical value pattern is DSV controllable, the address value of the selectable bit position of the logical value is stored in the address pointer 24 and the DSV operation & sign determination unit 26. Is supplied to.
The provisionally determined combined bit, the address of the selectable bit position, and the subsequent modulation code block data are supplied to the DSV control & code determination unit 26. Then, on the basis of these data, the fluctuation of the DSV corresponding to the logical value of the selectable address is calculated, and the logical value that optimizes the DSV is obtained as described above. As a result, the logical value of the subsequent modulation code block and the logical value of the combined bit are determined.

When changing the logical value of the provisionally determined combined bit, the logical value is changed to that logical value, and when there is no need to change, the provisionally determined logical value is determined as the logical value of the combined bit. To do. The above modulation processing operation is shown in FIG.
~ As shown in Fig. 6.

The address value whose logical value can be selected is stored in the pointer register 24 as described above, and the address is designated by the pointer register 24 when the address is counted by the address counter 28. Then, the logical value of the designated address is calculated by the DSV calculation & sign determination unit 2
The final set values are stored in the memories 20 and 21, respectively.

The 15-channel bit data and the combined bit of the modulation code block after being stored in the memories 20 and 21 are output in parallel to the parallel-serial conversion units 30 and 32, where they are serially converted to the NRZI conversion unit. Three
2 and 33 respectively. NRZI converter 32,
In 33, based on the input data, it is inverted with the logical value "1",
For "0", a non-inverted NRZI modulated signal is generated. The modulation signal of the NRZI conversion unit 32 is supplied to the optical modulator drive circuit 34, and the modulation signal of the NRZI conversion unit 33 is supplied to the deflector drive circuit 35.

The disk 36, which is a recording medium, has a light source 3
After the recording light output from the optical modulator 8 is modulated by the optical modulator 40 and deflected by the deflector 41, the projection optical system 42
Is radiated through. In the optical modulator drive circuit 34,
The optical modulator 40 is driven corresponding to the input first modulation signal. That is, the light supplied from the light source 38 is modulated by the optical modulator 40 based on the first modulation signal. As a result, optical modulation is performed corresponding to the presence or absence of pits in the track direction.

In the deflector drive circuit 35, the input second
The deflector 41 is driven according to the modulated signal of. That is, the light supplied from the optical modulator 40 is deflected by the deflector 41 based on the second modulation signal. As a result, optical modulation corresponding to the displacement of the pits in the track orthogonal direction is performed. Then, pits and lands are formed on the disk 36 based on this modulated light.

<Demodulator> Next, the demodulator will be described with reference to the block diagram of FIG. The device shown in the drawing is an example in which the demodulating device of this embodiment is applied to a disc reproducing device for reproducing a signal read from the disc 36 recorded by the disc recording device shown in FIG.

In the figure, a light source 5 such as a semiconductor laser is provided.
The read light beam output from 0 passes through the beam splitter 52 and enters the disk 36 through the read optical system 54. Then, the read light that has been modulated by the pit train of the disk 36 enters the beam splitter 52 again, is reflected there, and enters the two-divided photodetector 56. The outputs of the respective division detectors of the photodetector 56 are the adder 58 and the subtractor 6
The values are input to 0, and addition and subtraction operations are performed respectively. The output of the adder 58 is a reproduction signal in which the presence or absence of a pit is detected, and the output of the subtractor 60 is a reproduction signal in which the displacement of the pit is detected.

In the slice circuit 62, the reproduction signal for detecting the presence or absence of pits is binarized, and based on this, the PLL circuit 6
At 4 clock pulses are obtained. The input / output of the PLL circuit 64 is ANDed by the AND circuit 66, whereby the clock pulse of only the portion having the pit is taken out. This clock pulse is supplied to the sample hold circuit 68, where it operates as a sampling pulse. In addition,
The output of the slice circuit 62 is supplied to the synchronization signal detection circuit 74, and the synchronization signal detected here is supplied to the memory and determination circuit 72.

The output of the sample hold circuit 68 is A /
Memory and determination circuit 7 after A / D conversion by D converter 70
2 is stored, and it is determined whether the displacement is an inner displacement or an outer displacement in the track orthogonal direction. The first demodulated signal obtained by this determination, that is, the demodulated signal corresponding to the presence or absence of pits in the track direction, is stored in the combined bit memory (displayed in mb) 76, the shift register 78, the combined bit memory 80, and the shift register 82. Stored in array order. On the other hand, the second demodulated signal obtained by the determination,
That is, the demodulated signal corresponding to the displacement of the pits in the track orthogonal direction is the combined bit memory 77, the shift register 79,
The combined bit memory 81 and the shift register 83 are stored in the order of arrangement.

Then, the code converter 84 refers to the 3-bit logical values of the shift registers 78 and 82 on the combined bit memory 80 side and the combined bit logical values of the combined bit memory 76. The code conversion unit 84 performs a demodulation process that is the reverse of the modulation process, and converts the logical value of the corresponding bit in the shift registers 78 and 82. On the other hand, the shift register 7
The code converter 85 refers to the 3-bit logical value of each of the 9 and 83 combined bit memories 81 and the combined bit logical value of the combined bit memory 77. The code conversion unit 85 performs a demodulation process that is the reverse of the modulation process, and converts the logical value of the corresponding bit in the shift registers 79 and 83.

Thereafter, the 15-channel bit data respectively stored in the shift registers 82 and 83 are supplied to the demodulation table 86, and are converted back to 10-bit data by referring to Table 4 to obtain the demodulated output.

As described above, according to this embodiment, first, an optical recording apparatus is prepared which puts information on both the presence or absence of a bit in the track direction on the disc and the slight displacement of the bit in the track orthogonal direction. . Then, a digital modulation method for converting m-bit digital data into n-bit digital modulation data by using a modulation method having first and second code forming means is applied. This allows
A DR larger than that of the background art can be realized. For example,
The conversion parameters (d, k, m, n) are (2, 13, 1)
If the modulation method of 0, 16) is adopted, DR = 1.88
Which is 1.25 times that of the 4/8 modulation method. That is, the linear recording density on the disc is increased by 25%.

<Other Embodiments> The present invention can be variously modified based on the above disclosure, and includes, for example, the following. (1) The above embodiment is a case of conversion between 10-bit data and 16-channel bit data, where Tmin = 3 and Tmax
However, those values may be changed as needed. For example, the following combinations are useful. Tmin = 3 8-bit data → 13 channel bit conversion Tmin = 3 10-bit data → 15 channel bit conversion Tmin = 3 12-bit data → 18 channel bit conversion In the above embodiment, m = 10. Above, it may be below.

In the present invention, generally, conversion of m-bit digital data and an n (n> m) -bit digital modulation code of Tmax = k + 1 is performed by inserting a d-1 bit combination bit. The present invention is applicable to digital modulation / demodulation in which conversion of substantially m-bit digital data and (n + d-1) -bit digital modulation code is performed. Further, although NRZI is applied in the above embodiment, another method may be used.

(2) In the above embodiment, the present invention is applied to the recording and reproducing of the data on the disk, but in the case of recording and reproducing the data on the recording medium such as another tape or transmitting the data. However, the present invention is applicable. Further, the device configuration can be modified in various ways so as to achieve the same operation.

[0069]

As described above, the present invention has the following effects. (1) n (including m-bit digital data including modulation information in the track direction and the orthogonal direction thereof) is converted by using a conversion table that is predetermined so as to satisfy a predetermined inversion interval condition and a pit / land connection condition. (n> m) conversion into a digital modulation code of channel bits, and a combination bit of logical value satisfying the condition of the inversion interval is inserted between two consecutive blocks of the digital modulation code of n bits obtained by this. Therefore, the information density in modulation, demodulation, or transmission can be improved.

(2) Predetermined value V in the conversion table
For (≠ 0), the modulation code of CDS> V and CDS <V
Including the modulation code of, and it was decided to select one of those modulation codes so that DSV approaches V,
Control of the DSV becomes easy. (3) By improving the information density, the recording medium can be efficiently used and miniaturized.

[Brief description of drawings]

FIG. 1 is a diagram showing a modulation processing method according to an embodiment of the present invention.

FIG. 2 is a diagram showing a modulation processing method according to an embodiment of the present invention.

FIG. 3 is a diagram showing a modulation processing method according to an embodiment of the present invention.

FIG. 4 is a diagram showing a modulation processing method according to an embodiment of the present invention.

FIG. 5 is a diagram for explaining a maximum inversion interval according to the embodiment.

FIG. 6 is a diagram showing a modulation processing method according to the embodiment of the present invention.

FIG. 7 is a block diagram showing a main part of a disk recording device to which the modulator of the embodiment is applied.

FIG. 8 is a block diagram showing a main part of a disc reproducing device to which the demodulating device of the embodiment is applied.

[Explanation of symbols]

10, 11 ... Conversion ROM (data conversion means) 12, 13, 14, 15 ... Register 16 ... Synchronous code output section 18 ... Selector 20, 21 ... Memory (code sequence generation means) 22, 23 ... Combined bit processing section (code) Sequence generation means) 24 ... Pointer register 26 ... DSV operation & code determination unit 28 ... Address counter 30, 31 ... Parallel-serial conversion unit 32, 33 ... NRZI conversion unit 34 ... Optical modulator drive circuit 35 ... Deflector drive circuit 36 ... Disc (recording medium) 38 ... Light source 40 ... Optical modulator 41 ... Deflector 42 ... Projection optical system 50 ... Light source 52 ... Beam splitter 54 ... Reading optical system 56 ... Photodetector 58 ... Adder 60 ... Subtractor 62 ... Slice Circuit 64 ... PLL circuit 66 ... AND circuit 68 ... Sample hold circuit 70 ... A / D converter 72 ... Memory / judgment circuit (demodulation processing 74 ... Synchronous signal detection circuit 76, 77, 80, 81 ... Combined bit memory (demodulation processing means) 78, 79, 82, 83 ... Shift register (demodulation processing means) 84, 85 ... Code conversion section (demodulation processing means) ) 86 ... Demodulation table (data inverse conversion means) mb ... Combined bit

Claims (10)

[Claims] 1. The m-bit digital data includes modulation information in a track direction and in a direction orthogonal thereto by using a conversion table predetermined so as to satisfy a predetermined inversion interval condition and a pit / land connection condition. A data conversion step for converting a digital modulation code of n (n> m) channel bits; a combination bit of logical value satisfying the condition of the inversion interval between two consecutive blocks of the digital modulation code of n bit obtained by this. A digital modulation method including a code sequence generating step of inserting. 2. The m-bit digital data includes modulation information in the track direction and the orthogonal direction thereof by using a conversion table that is predetermined so as to satisfy a predetermined inversion interval condition and a pit / land connection condition. Data conversion means for converting a digital modulation code of n (n> m) channel bits; a combination bit of a logical value satisfying the condition of the inversion interval between two consecutive blocks of the n-bit digital modulation code obtained thereby. Code sequence generation means to be inserted;
A digital modulator including a. 3. The conversion table comprises: a first code formation table for data conversion corresponding to a track direction; a second code formation table for data conversion corresponding to a track orthogonal direction; 3. The digital modulator according to claim 2, wherein the code forming table uses a code corresponding to the presence / absence of displacement indicating whether the pit described with respect to the previous pit is displaced in the track orthogonal direction. 4. The conversion table includes a modulation code of CDS> V and a modulation code of CDS <V for a predetermined value V different from 0, and the data conversion means has a DSV of V
4. A digital modulator as claimed in claim 2 or 3, wherein either of the modulation codes is selected so as to approach 5. m = 10, n = 16, maximum inversion interval Tma
x = 14 and minimum inversion interval Tmin = 3.
Alternatively, the digital modulation device according to 4 above. 6. A synchronization pattern adding means for adding, as a synchronization pattern, data of a logical value pattern that continues while the number of “0” s exceeding the condition of the maximum inversion interval among the conditions of the inversion interval is “1”. The digital modulator according to claim 2, 3, 4, or 5. 7. A step of obtaining a recording signal based on the digital data modulated by the digital modulation method according to claim 1, and a step of recording the data on a recording medium based on the recording signal obtained thereby. A method of manufacturing a recording medium including the same. 8. A recording medium on which digital data is recorded by the method for manufacturing a recording medium according to claim 7. 9. The combination of the digital data reproduced from the recording medium according to claim 8 and a logical value of a modulation code before and after the combined bit are referred to perform a demodulation process reverse to the modulation process to obtain an n-channel bit. A demodulation processing step for obtaining a digital modulation code; a data inverse conversion step for performing an inverse conversion to the data conversion means on the digital modulation code of n channel bits demodulated thereby to obtain m bits of digital data. Demodulation method. 10. The combined bit of the digital data reproduced from the recording medium according to claim 8 and the logical value of the modulation code before and after the combined bit are referred to perform demodulation processing reverse to the modulation processing, and the n-channel bit Digital demodulation processing means for obtaining a digital modulation code; data inverse conversion means for performing an inverse conversion to the data conversion means on the digital modulation code of n channel bits demodulated thereby to obtain m-bit digital data Demodulator.