JP2003223762A - Encoded information decoding method, recording device, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the amount of data allocated to a unit area on a recording medium. <P>SOLUTION: An encoding method and circuit satisfy the requirements on the original data having a limited amount of bits when they are disposed two dimensionally, and generates channel data having the limited amount of bits to store on a limited area. The recording method and device record the generated channel data having the limited amount of bits on a limited area according to the above two dimensional layout. The recording medium stores the channel data having the limited amount of bits on the limited area according to the above two dimensional layout. The reproducing method and device reproduce the channel data having the limited amount of bits stored as above. The decoding method and circuit decode thus reproduced channel data having the limited amount of bits into the original data. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data recording method and a reproducing method on a recording medium such as an optical disk.

[0002]

2. Description of the Related Art Digital audio and video AV (A
A storage device for storing data handled by a host (computer) such as audio visual (HD) data and files is a magnetic disk device called HDD (Hard Disk Drive) or a CD (Compact Drive).
sc) and DVD (Digital Versatile)
An optical disc device using an optical disc of a standard called Disc), or MO (Magnet-Optica)
1) There is a magneto-optical disk device using a magneto-optical disk called a disk. The storage device also includes a magnetic tape device, a magnetic drum device, a magnetic card device, an optical card device, and the like.

Further, the storage device includes a ROM (Read
A memory dedicated to read (reproduction) in which data cannot be written (recorded) at the time of use called “Only Memory”, or a DRAM (Dynamic)
Random Access Memory) and SRAM
(Static Random Access Mem
RAM (Random Acc)
There is also a recordable and reproducible memory called ess Memory) and a semiconductor memory such as a non-volatile memory called flash (FLASH).

When a storage device receives logical data to be recorded from a higher-level system (a part for compressing digital audio / video data, a computer host, etc.), the storage device generally receives it before recording it on a storage medium. To add some control information or to correct an error that may occur during the playback (the process from the recording by the recording system to the storage on the storage medium to the playback on the playback system) during playback. It also performs error correction coding. In the present specification, data to be subjected to channel constraint coding, which will be described below, such as logical data, data to which control information is added, or data obtained by performing error correction coding on them is referred to as original data. Some storage devices have a certain channel characteristic, and it is difficult to record the original data as it is on the storage medium as it is, or even if it can be recorded, it can be recorded efficiently. There are things that are difficult to reproduce.

In order to solve the problem, such a storage device performs channel constraint coding on the original data with a channel constraint code considering the characteristics of the channel,
The resulting channel data is recorded on the storage medium at the intended location to be recorded. Specifically, for example, in an optical disc device, by applying a light beam for recording to that portion, and in, for example, a magnetic disc device, a magnetizing head magnetizes the portion so that channel data is written to a storage medium. Record.

In many storage devices, digital A
V data, computer data, data to which control information is added, and error-correction-coded data are binary sequences,
Furthermore, the channel data is also a binary series. Each bit of such channel data is stored in the pit (hole) / non-pit state of the storage film in, for example, a perforated optical disc, or in the phase change type optical disc. Is in a crystalline / amorphous state, and, for example, in a magnetic disk, the magnetic substance is in one of two different magnetization directions. It is physically distinguished and stored. Further, in the semiconductor memory, the two values are electrically distinguished and stored by holding one of two different potentials in the storage element.

Upon receiving a reproduction request for the data stored in this way from the higher-level system, the storage device reproduces the channel data from the target portion of the storage medium to be reproduced. Specifically, for example, in an optical disk device, a light beam is applied to the spot to detect the intensity (reproduction signal) of the reflected light (or transmitted light), and in the magnetic disk device, for example, a magnetic detection head. Detects the magnetization direction at that location to reproduce the channel data from the storage medium.

Next, the storage device reproduces the original data by decoding the channel data (inverse conversion for the channel constraint coding). After that, the storage device performs error correction or the like on the original data if necessary, and finally sends the intended logical data to be reproduced to the host system.

The channel constraint code is also simply called a channel code, a constraint code, a recording code or a modulation code.
Run length limitation (RL) is one of the typical channel constraint codes.
L, Run Length Limited) code. The run length is also called an inversion interval or constraint length, and means the length (number of bits) of continuous data with the same value. For example, a binary sequence "0" consisting of all 20 bits
001110000011100011111 "is a run of length 0 (run length) 3 first, followed by a run of length 2 1 followed by a run of length 5 0 and then a run of length 3 1 , Followed by a run of 0s of length 3 and then finally a run of 1s of length 4. A run-length limited code is the same value for channel data as a predetermined bit. The constraint is such that it is continuous for longer or longer or does not exceed a predetermined bit length.The former constraint is called the minimum run length constraint, and the latter is called the maximum run length constraint. It can be said that this is a sequence with a minimum run length of 2 and a maximum run length of 5.

The main purposes of constraining the minimum run length are: The run length is, so to speak, a logical length, and when this is multiplied by the bit pitch of the channel data in the storage medium, it becomes the physical inversion interval of the state on the storage medium track. If the physical reversal interval is too small, it may be difficult to control the light beam or the magnetizing head during recording to so record on the storage medium. Also, if the physical inversion interval is too small, during playback, waveform changes such as reduction of the playback signal amplitude and peak phase shift due to interference of neighboring channel data in the track direction may become noticeable. . This interference is due to intersymbol interference (I
SI, InterSymbol Interferen
ce) is called. When the influence of inter-symbol interference increases, it becomes difficult to correctly reproduce the channel data from the reproduced signal. Therefore, we constrain the minimum run length.

The main purposes of constraining the maximum run length are: The storage device plays back the playback signal and channel data during playback.
And the allocation with the corresponding original data must be known, that is, they must be synchronized. However,
For example, in a disk device, there may be unevenness in the rotation of the disk. Therefore, if the channel data are many and continuous with the same value, the storage device will erroneously recognize the continuous number during playback. So-called synchronization deviation may occur. If the synchronization shift occurs, subsequent reproduction signals will be assigned to uncorresponding original data until synchronization can be established again, which leads to an error in the original data. Therefore, it limits the maximum run length.

There are various kinds of constraints other than the minimum run length and the maximum run length, and various channel constraint codes have been developed in accordance with them. For example, in some storage devices, the DC component or low frequency component of channel data may adversely affect the servo processing during reproduction as noise. Therefore, there is a channel constraint code that is constrained to suppress the DC component and low frequency component of the channel data.
Also, in a certain storage device, even if the minimum run length that may be difficult to reproduce due to the influence of inter-symbol interference as described above, channel data in which the minimum run length is repeated within a predetermined number of times is relatively easy to reproduce. In some cases, it is more difficult to reproduce the channel data in which the minimum run length is repeated more than the predetermined number of times. Therefore, there is a channel constraint code that constrains the channel data so that the minimum run length is not repeated more than a predetermined number of times.

Various coding tables used in conventional channel-constrained coding / decoding are Codes for Mas.
s Data Storage Systems (Sh
non Foundation Publications
rs, The Netherlands, 1999)
Familiar with. Hereinafter, this is referred to as a first document in the present specification. In addition, a conventional coding method for a channel-constrained coding / decoding is a symbolic Dyn method.
amics and Coding (Cambridge)
e University Press, 1995)
Familiar with. Hereinafter, this is referred to as a second document in this specification. In fact, in the second document, for example, the second document 14th
MFM (Modified) shown in Figure 5.2.3 on page 8
Like a coding graph for a Frequency Modulation code, a coding graph is exemplified instead of a coding table.

However, the second document, page 148, FIG.
The coding graph of 2.3 is the same coding graph as that of FIG. 5.1 of Item 84 of the 1st document, and if this is used,
It will be understood that the coding graph and the coding table can be interchanged with each other because the coding table in Table 5.3 can be constructed.

By the way, the storage capacity and the reliability are important items representing the performance of the storage device. For example, in a disk device, the storage capacity has various conditions other than the area of the storage medium, such as track density (reciprocal of track pitch), linear density (reciprocal of bit pitch of channel data), and performance of channel constraint code. Related to. Reliability is also related to these various conditions.

Since a disk device generally scans (records or reproduces) a target track in the track direction,
From the relationship of the channel data, the characteristic of the channel constraint code appears in the neighboring channel data in the track direction as described above (for example, in the case of the channel constraint code with the minimum run length constrained to 2, the same value is obtained). However, channel data that is said to be unrelated to each other is stored in adjacent tracks. Therefore, there is a margin between tracks so that adjacent tracks do not adversely affect each other. Narrowing the margin between tracks,
That is, when the track pitch is reduced, the storage capacity increases. However, if the track pitch is too small,
Inter-track interference (ITI, InterTrack int) in which signals of neighboring tracks interfere as noise during reproduction.
The influence of interference (so-called crosstalk) may increase, and it may be difficult to correctly reproduce the channel data. On the other hand, if the track pitch is too large, the influence of the inter-track interference may be reduced and the data may be easily reproduced, but the storage capacity decreases, which is not practical.

The same applies to the bit pitch of channel data. If the bit pitch of the channel data is too small, the storage capacity increases, but the influence of inter-symbol interference increases as described above, and it may be difficult to correctly reproduce the channel data. On the other hand, if the channel data bit pitch is too large, the influence of inter-symbol interference may be reduced and reproduction may be facilitated, but the storage capacity is reduced and it is not practical. In addition, in the channel-constrained code, the one that can improve the reliability generally has a large redundancy (small coding rate), so that the storage capacity is reduced.

On the other hand, if the redundancy is small (the coding rate is large), the storage capacity can be increased, but the reliability is generally deteriorated. As described above, in order to develop a high-performance storage device, it is important to set an appropriate track pitch and a bit pitch of channel data and to develop an efficient channel constraint code.

In comparison with the above-mentioned conventional storage device, there is an attempt to improve the storage capacity as disclosed in JP-A-10-302407. Hereinafter, this is referred to as a third document in the present specification. The third document relates to a method for recording and reproducing original data on a storage medium capable of two-dimensionally storing data by performing a two-dimensional run length limiting encoding process, and an apparatus using these methods. .

The optical disc of the third document has substantially no radial (between tracks) margin, and the bits of the channel data between adjacent tracks are synchronized (the period and the phase are matched). Then, in order to suppress the influence of the inter-track interference that increases due to the absence of the radial margin, the channel data is not limited to the circumferential direction (track direction) as in the storage device described above, but to the radial direction. Also limits the run length, and two-dimensionally limits the run length.

In the example of the third document, the minimum run length in the radial direction is 2, and the minimum run length and the maximum run length in the circumferential direction are 2 respectively.
And 16 are restricted. The encoding is the original data 4
The bits are converted into matrix cells of channel data of 3 bits in the radial direction × 3 bits in the circumferential direction. FIG. 50 of the third document showing an example of the arrangement of pits on the optical disc in the third document is reproduced in FIG. 25 of the present specification. Note that, in order to facilitate understanding, FIG. 25 is different from FIG. 50 of the third document in that the light spot is removed and a dotted line showing a bit cell of channel data and channel data of 3 bits in radial direction × 3 bits in circumferential direction. The thick dotted line indicating the matrix cell is added, but it does not depart from the essential contents of the third document.

In the third document, at the time of recording, the storage device firstly adjoins the preceding channel (for example, on the left side in FIG. 25) adjacent to the location of the matrix cell of the target channel data in the circumferential (lateral) direction. A matrix cell of data,
Corresponding to 4 bits of original data among some patterns satisfying the run length constraint for matrix cells of adjacent (for example, upper adjacent in FIG. 25) channel data adjacent in the radial direction. One of them is selected as the matrix cell of the channel data at that location, and then the matrix cell of the selected channel data is recorded at that location. According to the third document, by repeatedly generating such a matrix cell of partial channel data for each location, channel data of an infinite region in a radial direction and a circumferential direction, that is, an infinite region is generated. Each bit cell of the channel data so generated is
The run length constraint is satisfied in the infinite region.

[0023]

However, although the size of the storage medium of an actual storage device such as a magnetic disk device or an optical disk device is finite, in the third document, the channel is limited to a finite area. Generating data is not mentioned. Even if the generation of the matrix cell of the channel data of the third document is stopped for a predetermined number of times in the vertical direction and the horizontal direction to generate the channel data of the finite area, the channel data has a particularly minimum run at the boundary. It may no longer meet the constraint on length. That is, there are cases where the run length becomes 1 at the boundary even though the minimum run length is restricted to 2. Therefore, the third document is not suitable for an actual storage device.

Furthermore, the encoding method of the third document is not clear in principle (theoretical) feasibility. As an example,
In FIG. 26 in which the minimum run length is restricted to 2 in both the vertical and horizontal directions, a matrix cell of channel data of 3 bits in the vertical direction × 3 bits in the horizontal direction indicated by a thick line is selected as a target matrix cell for 4 bits of original data. I will give you the case. Here, the upper and left neighboring matrix cells of the target matrix cell have been decided (preceding) as shown in the figure, and the lower and right neighboring matrix cells have not been decided (following). There is). Also, in this figure, it is assumed that the bit "0" of the channel data is shown in white and the bit "1" is shown in dark gray. In this case, the upper left bit in the target matrix cell is forced to '0' in order for the bit to the left of it to satisfy the lateral minimum run length constraint. In addition, the middle left bit in the target matrix cell is forced to '0' so that the upper left adjacent bit, '0', is forced to meet the vertical minimum run length constraint.

Similarly, in order for neighboring bits to satisfy the constraint, the lower left, middle upper, middle, middle lower, upper right, right middle and lower right bits in the target matrix cell are '1' and '1', respectively. , '0', '0', '1', '1',
I am forced to '0'. That is, to satisfy the constraint,
The target matrix cell is forced as shown by the thick line in FIG. (Here, for example, the right middle bit in the matrix cell does not seem to meet the lateral minimum run length constraint at this stage, but the matrix cell to the right of the matrix cell is undetermined at this stage. Therefore, there is no problem because the constraint must be satisfied when selecting the matrix cell on the right side.) That is, in this case, only one pattern can be selected as the target matrix cell, and this matrix cell has information Means that cannot be assigned.

However, it is necessary to allocate at least 4-bit information of the original data to this matrix cell. If it cannot be allocated as in this example, the information that could not be allocated can be allocated to the subsequent matrix cells (for example, if you try to allocate only to the matrix cell on the right side, the matrix cell on the right side May need to allocate 8 bits of information in addition to the 4 bits that originally need to be allocated). However, since the method is not shown in the third document, it is unclear whether or not it can be realized in principle (theoretical), and the position and the number of subsequent matrix cells to which information is assigned are unknown. The position and number of subsequent matrix cells to be reproduced to recover the original data is also unknown.

A main object of the present invention is to provide an encoding method for encoding original data into channel data for recording at high density on a storage medium of a finite size which can be two-dimensionally stored. It is to provide the circuit. A further object of the present invention is to provide a recording method and apparatus for recording channel data generated by the encoding method or the circuit thereof in a storage medium. It is a further object of the present invention to provide a storage medium storing channel data recorded by the recording method or the apparatus thereof.

A further object of the present invention is to provide a reproducing method and apparatus for reproducing channel data stored in the storage medium. A further object of the present invention is to provide a decoding method and a circuit for decoding the channel data reproduced by the reproducing method or the apparatus thereof into the original data (inverse conversion for the encoding).

[0029]

In order to achieve such an object, the encoding method and the circuit thereof according to the present invention apply a predetermined constraint to the original data having a finite number of bits when it is arranged two-dimensionally. Generate a finite number of channels of data to fill and store in a finite area of the storage medium. Further, the recording method and the apparatus thereof of the present invention record the channel data of a finite number of bits generated by the encoding method or the circuit thereof in the finite area of the storage medium according to the two-dimensional arrangement. Further, the storage medium of the present invention stores, in its finite area, channel data having a finite number of bits recorded by the recording method or the apparatus thereof according to the two-dimensional arrangement. Further, the reproducing method and the reproducing apparatus of the present invention reproduce the channel data having a finite number of bits stored in the finite area of the storage medium. Further, the decoding method and its circuit of the present invention decode the channel data having a finite number of bits reproduced by the reproducing method or the apparatus thereof into original data having a finite number of bits.

According to the present invention, the density of the channel constraint code can be increased as compared with a general storage device (the information amount of the original data assigned to the unit area of the storage medium can be increased). Further, the present invention uses a storage medium of a finite size capable of storing two-dimensionally, such as a magnetic disk device, an optical disk device, a magneto-optical disk device, a magnetic tape device, a magnetic drum device, a magnetic card device, an optical card device,
It can also be implemented by an actual storage device such as a semiconductor memory.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, the encoding method and its circuit, the recording method and its apparatus, the storage medium, the reproducing method and its apparatus, the decoding method and its apparatus will be described in order, one by one or a plurality of respective embodiments.

First, a first embodiment of the encoding method of the present invention will be described. This consists of the following three steps, Step 1 to Step 3. Step 1 (original data dividing step): The original data having a finite number of bits is divided every predetermined number of bits. Step 2 (encoding table input step): The divided original data is sequentially input to an encoding table which is configured in advance. Step 3 (channel data output step): The channel data sequentially output from the encoding table with respect to the sequential input of the original data is sequentially output.

FIG. 1 is a diagram showing an encoding table used in the first embodiment of the encoding method of the present invention. This encoding table is an encoding table that inputs the current state of the encoding table itself and 1 bit of original data, and outputs the channel data of 1 bit in the vertical direction × 4 bits in the horizontal direction and the next state of the encoding table itself. . Also, when the channel data generated by this encoding table is two-dimensionally arranged, the minimum run length 2 is set in both the vertical and horizontal directions in the portions other than the vertical boundaries (generated first and last). Fulfill.

Since this encoding table corresponds to 1 bit of original data, step 1 (original data dividing step) divides the original data to be encoded into 1-bit units. Then, in step 2 (encoding table input step), the original data thus divided is sequentially input to the encoding table. In step 3 (channel data output step), the channel data sequentially output from the encoding table with respect to the sequential input is sequentially output. Steps 1 and 2 are, for example, a part (DR) that temporarily stores data that functions as a cache or a buffer.
When implemented in a storage device having a semiconductor memory such as AM), the part can store the original data and send the stored original data bit by bit to the encoding table.

The operation of this encoding table will be described in detail. As an example, the original data to be encoded is “011
6 bits of "001" and the state of the encoding table itself which should be preset before encoding is Q1. FIG. 2 is generated according to the first embodiment of the encoding method of the present invention. It is a diagram showing the converted channel data.
1 ″ is sequentially input as 0, 1, 1, 0, 0, 1 for each bit. First, for the state Q1 of the encoding table itself and the first bit 0 of the original data, the encoding table is a channel. The data “1111” (first line in FIG. 2) is output, and the next state of the encoding table itself is set to Q3.

Next, with respect to the state Q3 of the encoding table itself and the second bit 1 of the original data, the encoding table outputs channel data "1100" (also in the second row),
Further, the next state of the encoding table itself is set to Q2. Similarly, for the remaining 3rd to 6th bits 1, 0, 0, 1 of the original data, the coding table shows channel data "1100", "0000", "000".
0 ”,“ 0011 ”(similarly to the third to sixth rows
Rows) are sequentially output, and Q2, Q0, Q0, and Q1 are sequentially set to the next state of the encoding table itself.

FIG. 2 in which channel data is arranged two-dimensionally.
, There is the same value (polarity) next to each bit in each row in the figure in the horizontal direction (for example, for bit 1 in the second row, second column, to the left of the second row in the second row Same value for 1 column 1
Exists, and the same value exists in the vertical direction next to each bit except for the first row and the sixth row of each column (for example, for bit 0 of the second row and the third column). The same value 0 exists in the third row and the third column underneath.)

That is, this channel data satisfies the constraint of the minimum run length of 2 in the horizontal direction, and further, in the portions other than the vertical boundary (generated at the beginning and the end), that is, the first row and the sixth row in this example. The second to fifth rows other than the rows satisfy the constraint of the minimum run length 2 in the vertical direction. This encoding table is not limited to this example, and for original data of any length, if the encoding table is arranged in the vertical direction by 1 bit in the vertical direction × 4 bits in the horizontal direction, the encoding table will be displayed in the vertical direction except the boundary in the vertical direction. It will be appreciated that it outputs channel data that meets the minimum run length of 2 constraint in both the lateral and lateral directions.

The first embodiment of the encoding method of the present invention has been described above. Here, an example of a method of forming an encoding table that should be previously formed in the encoding method of the present invention will be described. Here, as an example, a method of configuring the coding table of FIG. 1 will be described.

To construct the encoding table, first,
A state transition (also called a Markov model or Marcov model) that outputs channel data satisfying a predetermined constraint is configured. FIG. 3 is a diagram showing a state transition in which channel data satisfying the constraint of the minimum run length 2 in both the vertical direction and the horizontal direction is output sequentially in the vertical direction by 1 bit in the vertical direction × 4 bits in the horizontal direction. For this state transition, q0 to q
There are 15 16 states (also called nodes, nodes).

Then, for example, in the state q7, "00" is displayed in the upper stage.
11 "and the label" 1111 "in the lower row, each state shows a label of 2 rows of upper and lower rows x 4 bits in the horizontal direction. The channel data selected at the time is shown, and the lower row shows the channel data selected at the present time.The reason why each state holds the channel data selected at the previous time in the label is that the run length in the vertical direction is held. By holding two points in total including the previous time point and the current time point, it is possible to express two types of run lengths in the vertical direction at the current time point, that is, 1 or 2 or more. Here, since the minimum run length in the vertical direction is limited to 2, the past selected channel data to be retained is sufficient from the current time point to the previous time point.Of course, the channel data selected at the previous time point is held. Rather, to hold a vertical run length itself at the current time, it is also possible to represent this state transition.

As described above, for example, in the state q7, the channel data is "0011" at the previous time point and "11" at the present time point.
This means that the current run length in the vertical direction is the first bit and the second in the horizontal direction.
It is 2 or more in the bit part, whereas it is 1 in the 3rd and 4th bit parts. Therefore, as the channel data at the next time, from the viewpoint of the run length in the vertical direction,
Either 0 or 1 can be selected as the first bit and the second bit, while only the same 1 as the one selected at the present time can be selected as the third bit and the fourth bit. Further, in consideration of the run length in the horizontal direction, two types of channel data “1100” and “1111” can be selected from the state q7 as the channel data at the next time point. When "1100" is selected as the channel data at the next time point, the state changes to the state q14 at the next time point, and when "1111" is selected, the state changes to the state q15 at the next time point. Therefore, there are transitions (also called branches or paths) from the state q7 to the states q14 and q15.

Although not shown in FIG. 3 for convenience, the transition from the state q7 to the state q14 has "1100" of the channel data to be selected at the next time as the first label,
Similarly, the transition from the state q7 to the state q15 is “111
1 ”as the first label. In FIG. 3, the first label of the transition not shown can be seen as the lower stage of the label of the transition destination state.

In this state transition, the first label of the transition is sequentially output as channel data. By setting the initial state arbitrarily in the state transition of FIG. 3 and arbitrarily selecting the transitions, the channel data generated thereby can be arranged in order in the vertical direction. It will be understood that, except for the last output), the constraint of the minimum run length 2 is satisfied in both the vertical and horizontal directions. Further, any channel data satisfying the constraint of the minimum run length 2 in both the vertical and horizontal directions except the boundary in the vertical direction and satisfying the constraint of the minimum run length 2 in at least the horizontal direction at the boundary in the vertical direction is in the state of FIG. It will be understood that it is possible to generate by appropriately setting the initial state in the transition and appropriately selecting the transition.

FIG. 4 is a diagram showing a transition matrix (also called a connection matrix) of the state transition of FIG. The matrix (i
The element at the (+1) th row and the (j + 1) th column is in the state q (i) of FIG.
Represents the number of transitions from the state to the state q (j) (0 ≦ i
≦ 15, 0 ≦ j ≦ 15). That is, in FIG. 3, for example, since there is one transition from the state q0 to the state q1,
The element in the first row and second column of this matrix becomes 1, and the state q
Since there is no transition from 1 to the state q0, the element in the second row and first column of this matrix becomes 0. The maximum eigenvalue of this matrix is approximately 2.6180. 2 to the bottom 2.6180
The logarithm of is about 1.3885.

This is a value indicating the amount of information generally called Shannon capacity, and from the theoretical viewpoint of the amount of information, the maximum asymptotically about the maximum for channel data of 1 bit in the vertical direction × 4 bits in the horizontal direction. This means that it is possible to allocate 1.3885 bits. It should be noted here that an attempt is made to construct a coding table that allocates 1 bit of original data (1 bit at most as information amount) to channel data of 1 bit in the vertical direction × 4 bits in the horizontal direction. For the maximum eigenvalue of a matrix, please refer to a detailed technical book on mathematics and matrices, and on Shannon capacity, please refer to a detailed technical book on information theory.

After constructing the state transition of FIG. 3 for outputting channel data satisfying a predetermined constraint, the states of the state transition and the transitions are appropriately combined, divided or removed, and all states (here In order to allocate 1 bit of the original data), modify the state transition so that two transitions will occur, and then, for the two transitions from each state of the modified state transition, 0 will not overlap each other. Or 1 for the second
(The second label corresponds to the original data, which will be described later).

Here, the corrected state transition is sequentially output at a predetermined time point. In the vertical direction, with respect to arbitrary channel data of the number of bits for the predetermined time point × 4 bits in the horizontal direction, such a channel is set. Second transition that can output data
The second label of the transition shall be assigned so that the label is unique. This property is utilized by the decoding method of the present invention, which will be described later, corresponding to the above-described encoding method, in order to uniquely decode the channel data into the original data. One method of appropriately combining, dividing, and removing the states of the state transitions and then assigning the label corresponding to the original data to the transitions is described in detail in the second document of the related art.

FIG. 5 is a diagram showing a state transition in which the state transitions shown in FIG. 3 are modified so that two transitions are obtained from all the states by appropriately combining, dividing, and removing the states and transitions. is there. Further, FIG. 6 shows the second transition of the state transition of FIG.
It is a figure which shows the state transition which assigned the label of. A label is shown on each transition of the state transitions in FIG. 6, for example, “0/0000” of the transition from the state q0 to the state q0.
One bit to the left of the character '/' in this label is the second label for that transition. On the other hand, the character '/' on this label
The four bits to the right are the first label for that transition.
This state transition functions as a coded graph. In fact
For a 1-bit input of raw data, this coded graph is
Of the two transitions from the current state, the one whose first label is equal to 1 bit of the original data is selected, and the second label is output as channel data of 1 bit in the vertical direction × 4 bits in the horizontal direction, Further, by setting the transition destination state as the next state, it functions as a coding graph. It will be appreciated that the encoding graph can be read from and to the encoding table of FIG.

In the above description, the constraint of the minimum run length 2 is given in both the vertical direction and the horizontal direction, but this is an example, and the constraint given to the channel data to be generated by the coding method of the present invention is not limited thereto. Generally, the constraint given to the channel constraint code is determined in consideration of various factors such as the bit pitch of the channel data of the storage medium and the reproduction signal processing, but the channel data to be generated by the encoding method of the present invention is Various restrictions can be imposed.

For example, the minimum run length does not have to be restricted in one or both of the vertical direction and the horizontal direction, the minimum run length may be restricted to a value other than 2, and the maximum run length may be restricted. May be constrained, a direct current component or a low frequency component may be constrained, or a minimum run length may not be repeated beyond a predetermined number of times. Further, instead of restricting the two directions of the vertical direction and the horizontal direction, it is possible to restrict not to include a predetermined two-dimensional pattern in the case of two-dimensional arrangement. It may be constrained to consist of a predetermined two-dimensional pattern. Other constraints other than these may be used. Regardless of which constraint is given, for example, if the coding table is constructed by applying the above-described coding table construction method, first, a state transition that outputs channel data satisfying the given constraint is performed, and then, It suffices to appropriately combine, divide, and remove states and transitions with respect to the state transitions, and then assign labels corresponding to the original data to the transitions to configure the encoding table.

In the above description, the encoding table for generating channel data of 1 bit in the vertical direction × 4 bits in the horizontal direction with respect to 1 bit of the original data has been described. The unit of the original data and the channel data is not limited to this. Of course, it is also possible to configure an encoding table for generating channel data of M bits in the vertical direction × N bits in the horizontal direction for the original data L bits (L, M, and N are integers of 1 or more). Here, as a condition, L needs to be small with respect to the Shannon capacity obtained from the transition matrix formed later. The method of constructing such an encoding table will be described below.

First, a state transition for outputting channel data satisfying a predetermined constraint is arranged when M bits in the vertical direction × N bits in the horizontal direction are sequentially arranged in the vertical direction. Then, in each transition, channel data of M bits in the vertical direction × N bits in the horizontal direction to be selected is held as the first label. Here, for this state transition, the maximum eigenvalue of the transition matrix is derived, and if the logarithm of the value with the base of 2, that is, the Shannon capacity is less than L, then M bits in the vertical direction × N bits in the horizontal direction. Since the information amount L bits of the original data to be allocated is too large, the encoding table cannot be configured from the theoretical viewpoint of the information amount.

Next, the states and transitions are appropriately combined, divided, or removed, and the state transitions are modified so that 2 ^ L transitions are output from all the states. 2 ^ L is 2 here
Of the power of 2 and is, for example, 2 ^ 5 = 32. Finally, a binary number of 0 to ((2 ^ L) -1) is assigned as the second label so that the 2 ^ L transitions from each state do not overlap each other. Further, at this time, for a predetermined integer T of 1 or more, such channel data is output for arbitrary vertical direction T × M bits × horizontal direction N-bit channel data which is output at T transitions. The second label of the transition is assigned so that the combination of the second labels of the T transitions that can be output is unique. (Here, if the second label of the transition can be assigned with T = 1, it is possible to construct an encoding table that does not have the state of the encoding table itself at the input and the output. It can be understood that there are few parameters of output and output, and the contents to be held accordingly, which leads to reduction of hardware cost at the time of implementation and is effective.) The original data L bits input to the first label are associated with each other, and M bits in the vertical direction to be output to the second label of the transition × N in the horizontal direction.
By associating the bit channel data with each other, a coding graph and thus a coding table can be configured. When the encoding table configured in this way is used, in the first embodiment of the encoding method of the present invention, the original data is divided into L bits and sequentially input to the encoding table, The channel data of M bits in the vertical direction and L bits in the horizontal direction, which are sequentially output from, are sequentially output.

FIG. 7 shows the horizontal direction N, which is derived by the inventor and is restricted to the minimum run length 2 in both the vertical and horizontal directions.
It is a figure which shows the Shannon capacity (maximum amount of information) which can be allocated to the channel data of 1 bit of vertical direction x N bits of horizontal direction with respect to a bit. When N = 4, FIG.
As shown in FIG. 5, the size of the transition matrix is 16 rows × 16 columns, and the size of one side is 16. However, the state transition is logically compressed as described later as the second embodiment of the encoding method of the present invention. Then, the size of one side is 8. Also, the maximum eigenvalue of the transition matrix in this case (as described below,
The original state transition outputs the same channel data, so the transition matrix has the same maximum eigenvalue even if the size is different.)
And Shannon capacity (logarithm of maximum eigenvalue with base 2) is
As mentioned above, about 2.6180 and about 1.3885, respectively.
Is. Further, in this case, since the number of bits in the horizontal direction N = 4, the value obtained by averaging the Shannon capacity to each bit in the horizontal direction (that is, the Shannon capacity divided by the number of bits in the horizontal direction) is about 1.3885. ÷ 4 = about 0.3471. FIG. 7 shows the number of bits N in the horizontal direction similarly derived for 5 ≦ N ≦ 15.

It will be understood from FIG. 7 that the larger the number of bits in the horizontal direction, the larger the Shannon capacitance averaged in the horizontal direction. That is, in the implementation of the present invention, a larger number of bits in the horizontal direction may increase the amount of information that can be assigned per 1-bit channel data, which is advantageous from the viewpoint of storage capacity.

In addition to the above, the coding method and the coding table of the present invention input L bits of original data to the coding table and then input L bits of original data for L ≠ L ′. Then, the original data L'bits may be input and then the original data L bits may be input, so that the number of bits of the original data input to the encoding table may not be constant. In this case, in the method of constructing the above-mentioned encoding table, the states of the state transitions and transitions are appropriately combined, divided, or removed, and an appropriate number of all states (the original data to be assigned to that state) If the number of bits of is, for example, L bits, 2 ^ L transitions are modified so that an appropriate number of transitions from each state do not overlap with each other and an appropriate binary number (assigned to that state) If the number of bits of the original data to be power is L bits, for example, 0 to ((2 ^ L) -1)) can be assigned as the second label.

Further, although the above description has been given of the coding table for generating the channel data satisfying the predetermined constraint in the vertical direction by M bits in the vertical direction and N bits in the horizontal direction, the coding method of the present invention. The encoding table can be implemented in other ways. Vertical M bit ×
The horizontal N bits are a so-called rectangular area. Figure 8 ~
Each of FIG. 10 is a diagram showing a generation order of channel data generated by the encoding method of the present invention. The channel data in each of these figures is an example in which the horizontal direction is 5 bits and the vertical direction is generated in sequence. The numbers attached to the respective bit positions of the channel data are the vertical 8 bits × horizontal 5 bits In the region, it means that they are sequentially generated in that order. In each figure, there is a bit position of the channel data shown in gray, but this does not show the value of each bit of the channel data, but the vertical 8 bits x horizontal 5 bits of the channel data. It only shows the bit position of the sixth channel data generated in the region of.

That is, in FIG. 8, the vertical 8 bits × the horizontal 5
The channel data generated by the encoding table for the sixth original data for the bit channel data area is the second leftmost bit position from the top, the third leftmost bit position from the third, It means that they are arranged at the fourth middle bit position from the top, the fifth bit position from the right to the second bit position from the top, and the sixth rightmost bit position from the top. Further, in FIG. 9, the vertical 8 bits ×
The channel data generated by the encoding table for the sixth original data for the horizontal 5-bit channel data area is the sixth leftmost bit position from the top and the fourth leftmost bit position from the fourth. Means that they are arranged at the middle sixth bit position from the top, the fourth bit position from the right, the second bit position from the right, and the sixth rightmost bit position from the top.

Further, in FIG. 10, the channel data generated by the coding table for the sixth original data for the area of the channel data of vertical 8 bits × horizontal 5 bits is shown in FIG.
It is located at the 5th leftmost bit position from the top, the 2nd bit position from the left, and the middle bit position, and the 6th leftmost bit position from the top, the 2nd bit position from the left, and the middle bit position. It means that. In order to implement the encoding method and the encoding table of the present invention in the order of such bit positions, in the above-described method of configuring the encoding table, first, the state transition corresponding to such bit position and order is performed. It suffices to configure and derive the encoding table from the state transition. The bit position and the order of the channel data output by the coding method and the coding table of the present invention can be implemented in various ways other than those shown in FIGS. The first embodiment of the encoding method of the present invention has been described above.

Next, a second embodiment of the encoding method of the present invention will be described. This consists of the following four steps 1 to 4. Step 1 (original data dividing step): The original data having a finite number of bits is divided every predetermined number of bits. Step 2 (encoding table input step): The divided original data is sequentially input to an encoding table which is configured in advance. Step 3 (Relative channel data conversion step): Relative channel data sequentially output from the encoding table with respect to sequential input of the original data is sequentially converted into channel data. Step 4 (channel data output step): The sequentially converted channel data is sequentially output.

The second embodiment of the encoding method of the present invention is different from the above-described first embodiment of the encoding method of the present invention in step 1 (original data dividing step) and step 2.
(Encoding table input step) is the same, and step 3 is performed before step 4 (channel data output step).
The difference is that the (relative channel data conversion step) is performed. The second embodiment of the encoding method of the present invention differs from the above-described first embodiment of the encoding method of the present invention in the encoding table used.

In the above-described exemplification of the first embodiment of the encoding method of the present invention, the minimum run length is restricted to 2 in the horizontal direction of the width of 4 bits of the channel data. The second bit, the third bit, and the fourth bit always have the same value. Therefore, the encoding table does not have to hold the first bit and the fourth bit. If the encoding table does not hold such redundant bits, it leads to a reduction in the amount of hardware during implementation, which is advantageous. If these bits that the encoding table does not hold are necessary, they may be generated by copying the same value as the second bit as the first bit, for example.

Further, in the above-described exemplification of the first embodiment of the encoding method of the present invention, the same restriction is given to 0 and 1 of channel data. Therefore, the coding table of FIG. 1 is also configured without any difference from the viewpoint of 0 and the viewpoint of 1 of the channel data. That is, in the encoding table of FIG. 1, channel data 0 and 1 and states Q0, Q1, Q2, and Q3 are replaced with channel data 1 and 0 and states Q3, Q2, Q1, and Q0, respectively. The encoded table is the encoded table itself of FIG. This means that the encoding table of FIG. 1 holds the same contents from the viewpoint of 0 and the viewpoint of 1 of the channel data. Therefore, the encoding table of FIG. 1 holds the same content twice and is redundant.

Here, a method of forming an encoding table while logically compressing the above two types of redundancy will be described. FIG. 11 is a diagram showing a state transition in which channel data satisfying the constraint of the minimum run length 2 in both the vertical direction and the horizontal direction is sequentially output in the vertical direction by 1 bit in the vertical direction × 4 bits in the horizontal direction. That is, FIG. 11 is a state transition in which the same channel data is output although the configuration is different from the state transition in FIG.

The state transition of FIG. 11 will be described in detail. There are eight states q0 to q7 in this state transition. And, for example, as the state q7 is labeled with "10" in the upper stage and "00" in the lower stage, each state is labeled with the upper and lower two stages and the horizontal 2-bit label. The upper part of the two upper and lower labels is the second bit (the first bit is the same) of the channel data selected at the previous time with respect to the second bit (the first bit has the same value) of the channel data selected at the original time. Value) and the third bit (the fourth bit has the same value) as the relative (exclusive OR) value. On the other hand, the lower row shows the second bit (the first bit has the same value) of the relative channel data selected at the current time with respect to the second bit (the first bit has the same value) of the channel data selected at the original time and It shows the relative (exclusive OR) value of the third bit (the fourth bit has the same value).

This omits the description of the first and fourth bits in the horizontal direction of each label for the state transition of FIG. 3, and then the label of each state and the first of each transition exiting from that state. For each bit of the label of, the value relative to the first horizontal bit in the lower row of the label of that state is newly described (exclusive OR), and after that, the state transition has Is equivalent to the state transition with the redundancy removed. For example, in the horizontal direction of each label of the state transition of FIG.
After omitting the bit and fourth bit descriptions, each bit of the label of each state and the first label of each transition leaving that state is exclusive of the first horizontal bit of the label below that state. If the logical sum is taken, for example, the label of the state q0 is "00" in the upper stage, "00" in the lower stage, the label of state q2 is "11" in the upper stage, "01" in the lower stage, and the label of state q15 is in the upper stage. "00" and "00" at the bottom. It will be understood that the first horizontal bit of the lower row of each state label is always 0 because the exclusive OR is performed with the first horizontal bit of the lower row of the state label.

By describing as such, the state q in FIG.
0 and the state q15 have the same label, and the state q1 and the state q14 have the same label, and these states are equivalent. Then, by combining such equivalent states, the state transition of FIG. 11 is obtained. It should be noted that FIG. 11 is a state transition in which the redundancy of the state transition of FIG. 3 is removed, and thus the maximum eigenvalue of the transition matrix is the same as that of FIG. This can be understood from FIG. 11 and FIG. 3 that channel data under the same conditions can be output, and therefore the amount of information that can be assigned is the same from a theoretical point of view. With respect to the state transitions of FIG. 11, as in the method of constructing the encoding table described in the first embodiment of the encoding method of the present invention, the states are changed so that there are two transitions from all states. After modifying the transition, the second graph of the transition is assigned to construct the coding graph.

FIG. 12 shows two transitions from all states in the same manner as the method of constructing the encoding table described in the first embodiment of the encoding method of the present invention with respect to the state transition of FIG. FIG. 8 is a diagram showing a state transition in which the second label of the transition is assigned after the state transition is modified so that the transition of FIG. Here, the state transition diagram of FIG. 12 will be described in detail. For each transition of this state transition, for example, states q0 to q
The label is shown as "0/00" of the transition to 0. One bit to the left of the character '/' in this label is the second label for the transition. On the other hand, the character '/' on this label
The two bits to the right are the first label for the transition. As described above, each label is a value (exclusive OR) relative to the first horizontal bit in the lower row of the state label.

This state transition functions as a coded graph. In fact, for a 1-bit source data input, this encoding graph selects the one of the two transitions out of the current state whose first label is equal to 1 bit of the source data and assigns its second label to it. If the relative channel data of 1 bit in the vertical direction × 2 bits in the horizontal direction is output and the transition destination state is set as the next state, the relative channel data satisfying a predetermined constraint is sequentially output.

FIG. 13 is a diagram showing an encoding table used in the second embodiment of the encoding method of the present invention, which is obtained by replacing the encoding graph of FIG. This coding table is smaller in scale than the coding table of FIG. That is, the number of bits of channel data held in each state is reduced by omitting the description of the first and fourth bits in the horizontal direction of each label. In addition, each bit of the label of each state and the first label of each transition that exits from that state is relative (exclusive ORed) to the first horizontal bit of the lower stage of the label of that state By newly describing the value, the number of states is halved. It will be understood that such logical compression is effective, for example, in reducing the hardware cost at the time of implementation.

By the way, the coding graph of FIG. 12 and FIG.
The encoding table of outputs the relative channel data. The reason for being relative channel data is that each bit of the label of each state and the first label of each transition exiting that state is relative (exclusive) to the first horizontal bit below the label of that state. This is because the value has been newly described. As described above, the lower part of the label of each state before the new description shows the channel data selected at the present time. Further, the coding graph of FIG. 12 and the coding table of FIG. 13 output relative channel data at the next time point. Therefore, when the coding graph of FIG. 12 or the coding table of FIG. 13 is used, in the second embodiment of the coding method of the present invention, step 3 (relative channel data conversion step) is performed at the next relative point. The target channel data is converted to the next-time channel data. Specifically, as each bit of the channel data at the next time point, each bit of the relative channel data at the next time point is exclusive ORed with the first bit in the horizontal direction of the channel data at the current time point. Then step 4 (channel data output step)
The channel data thus obtained is output.

The operation of the encoding table shown in FIG. 13 will be described. As an example, the original data to be encoded is “0110
01 ″ 6 bits, and the state of the encoding table itself that should be preset before encoding is Q1, and the first bit in the horizontal direction of the channel data that should be preset before encoding. Is set to 1.

FIG. 14 shows the relative channel data generated by the second embodiment of the coding method of the present invention,
It is a figure which shows 1st channel data and 2nd channel data. The i-th row of the relative channel data in this figure is the relative channel data output from the encoding table with respect to the input of the i-th bit of the original data to the encoding table of FIG. 13 (1 ≦ i ≦ 6). In addition, the i-th row of the first channel data in this figure is the previous time point (i-1 row).
Of the relative channel data at the present time (the i-th row) with respect to the first bit in the horizontal direction of the channel data. It should be noted that the first row of the first channel data in this figure is the first row for the first horizontal bit of the channel data which should be preset before the encoding with the value set to 1 here. Is an exclusive logical loop of the relative channel data of. The second channel data in this figure is generated by duplicating the first column and the second column of the first channel data into the first column and the second column, and the third column and the fourth column, respectively. It was done.

In the second embodiment of the encoding method of the present invention, the channel data finally required for recording on the storage medium is 2 bits in the horizontal direction, and is in the vertical direction except at least the boundary in the vertical direction. If channel data satisfying the minimum run length of 2 is required, the first channel data of FIG. 14 may be output. In addition, channel data that is 4 bits in the horizontal direction and that satisfies the minimum run length of 2 in both the vertical and horizontal directions except at least the boundary in the vertical direction and that the minimum run length in the horizontal direction is at least 2 bits in the horizontal direction is required. If so, the second channel data in FIG. 14 may be output. In the above description, the encoding table is logically compressed by using the relative value with the first bit of the channel data selected at the present time as a reference.
It goes without saying that the encoding table can be logically compressed in the same manner by using a relative value based on other bits.

Further, in the above description, the logical compression is performed for both of the two types of redundancy. It will be understood that it will reduce the wear cost and it will be effective. The above logical compression is an example,
It can also be logically compressed for other redundancy.

For example, if the channel data (or relative channel data) held by the encoding table holds the same value in a plurality of columns (rows) of the encoding table, such encoding is performed. Instead of the table, the index of channel data (or relative channel data) to be input to the second encoding table and the next state of the encoding table itself with respect to the input of the current state of the encoding table itself and the original data. With respect to the input of the first coding table for outputting and the index of the channel data (or relative channel data) output by the first coding table, the corresponding channel data (or relative channel data) is input. You may change so that it may implement as a 2nd encoding table to output. By doing so, the channel data that should be held in multiple columns of the encoding table will be retained in a single column of the second encoding table, thus reducing the hardware cost during implementation. Be connected and understand that it works. Other than these, the encoding table of the present invention may have various configurations. The second embodiment of the encoding method of the present invention has been described above.

Next, a third embodiment of the encoding method of the present invention will be described. This consists of the following four steps 1 to 4. Step 1 (original data dividing step): The original data having a finite number of bits is divided every predetermined number of bits. Step 2 (encoding table input step): The divided original data is sequentially input to an encoding table which is configured in advance. Step 3 (appropriate channel data selection step): When there are a plurality of types of channel data that can be output by the encoding table with respect to the sequential input of the original data, the subsequent channel data are foreseen and the plurality of types of channels are selected. Select the appropriate channel data from the data. Step 4 (channel data output step): With respect to the sequential input of the original data, when there is one type of channel data that can be output by the encoding table, the channel data is selected, and when there are multiple types, the selected channel is selected. Data is output sequentially.

The third embodiment of the encoding method of the present invention is different from the above-described first and second embodiments of the encoding method of the present invention in step 1 (original data division step). ) And step 2 (encoding table input step)
Are the same, step 3 (appropriate channel data selection step) and step 4 (channel data output step)
Is different. The third embodiment of the encoding method of the present invention uses a different encoding table from the above-described first and second embodiments of the encoding method of the present invention.

Both the encoding tables used in the first and second embodiments of the encoding method of the present invention output the original data sequentially input and the state of the encoding table itself. The possible channel data was one type as described above. On the other hand, the encoding table used in the third embodiment of the encoding method of the present invention has a plurality of types of channel data that can be output depending on the original data that is sequentially input and the state of the encoding table itself. To do.

Here, a method for constructing such an encoding table will be described. First, a state transition is formed in which channel data satisfying a two-dimensional predetermined constraint is sequentially output in the vertical direction by M bits in the vertical direction × N bits in the horizontal direction. Each transition holds channel data of M bits in the vertical direction × N bits in the horizontal direction to be selected as a first label.
Next, the states and transitions are appropriately combined, divided, or removed, and the state transitions are modified so that 2 ^ L or more transitions are output from all the states. Further, at this time, the state transitions are modified so that the number of transitions exceeds 2 ^ L from at least one state. Finally, a binary number of 0 to ((2 ^ L) -1) is allowed at least once at least once as the second label for the transition of 2 ^ L or more transitions from each state.

Further, at this time, with respect to a predetermined integer T of 1 or more, with respect to the channel data of arbitrary vertical direction T × M bits × horizontal direction N bits output by this state transition at T transitions, Assign the second label of the transition such that the combination of the second labels of the T transitions that can output such channel data is unique. With respect to the state transition configured as described above, L bits of original data input to the first label of the transition are made to correspond to M bits of vertical direction × N bits of horizontal direction to be output to the second label of the transition. By associating the channel data, a coding graph capable of outputting a plurality of types of channel data can be configured depending on the conditions. An encoding table having the same meaning can be constructed from the encoding graph.

FIG. 15 is a diagram showing an encoding table used in the third embodiment of the encoding method of the present invention. This encoding table restricts the channel data to the minimum run length 2 in both the vertical and horizontal directions. Also, it should be understood that a plurality of types of relative channel data can be output depending on the divided bits of the horizontally sequentially input original data and the state of the encoding table itself.

For example, the state of the encoding table itself is Q0.
If the original data is 0, then "000", "011",
It is possible to output three types of channel data of "110". It should be noted that this encoding table is arranged in the vertical direction in the order of 1 bit in the vertical direction × 5 bits in the horizontal direction.
The minimum run length constraint of 2 bits is satisfied in the vertical direction except at least the vertical boundary (corresponding to the first bit of the original data and the last bit of the original data), and the minimum run length of 2 bits is constrained in the horizontal direction at the vertical boundary. It is used to output channel data that satisfies the above condition. The content is
Similar to the second embodiment of the encoding method of the present invention described above, the description of the first and fifth bits in the horizontal direction of the channel data is omitted, and the first bit in the horizontal direction of the current channel data is further described. The logical compression is tried by using the relative value by taking the exclusive OR of.

In the third embodiment of the encoding method of the present invention, in step 3 (appropriate channel data selection step), when there are a plurality of types of channel data that can be output from the encoding table, subsequent channel data is Look ahead and select the appropriate channel data. The foreseeable range is either all the subsequent channel data, the subsequent channel data for a predetermined number of bits, or the subsequent channel data until the encoding table can output a plurality of types for the first time. However, it may be other than these. Here, as an example of a method of selecting an appropriate one of a plurality of types of channel data that can be output,
One of selection methods for suppressing the DC component and the low frequency component in the vertical direction of the channel data will be described. In particular,
Of the absolute value of the difference between the value obtained by vertically accumulating the channel data up to the foresee range for each bit position in the horizontal direction and the function S / 2 for the vertical bit number S of the channel data up to the foresee range The channel data having the smallest maximum value is selected as an appropriate one.

This is because the maximum absolute value of the accumulated values when channel data 0 is -1 and 1 is 1 is equivalent to selecting the minimum channel data. Good. Of course, the accumulation target is not to vertically accumulate the channel data up to the foreseeable range for each bit position in the horizontal direction, but to vertically accumulate the channel data up to the foreseeable range at a predetermined horizontal bit position. Either one of accumulating or accumulating all channel data up to the foreseeing range may be used, or other than these. Also,
The function for the number of bits S in the vertical direction may be not S / 2 but another function or a constant for S.

Then, in step 4 (channel data output step) in the third embodiment of the encoding method of the present invention, if there is one type of channel data that can be selected by the encoding table, that channel data is selected. If there are a plurality of types, the channel data selected in step 3 is output.

FIG. 16 shows the vertical direction of the channel data generated by the third embodiment of the coding method of the present invention using the coding table of FIG. 15, in which the vertical direct current component and low frequency component are suppressed. It is a figure which shows the frequency characteristic of a direction. This figure shows 1048576 bits in the vertical direction output for 1048576-bit random original data by the encoding method that functions to suppress the direct current component and low frequency component in the vertical direction using the encoding table of FIG. C. This is the result of performing frequency analysis in the vertical direction on each of the horizontal 5-bit channel data for each bit position in the horizontal direction.

More specifically, the analysis result of FIG.
100 kinds of such original data are prepared, and the results of analysis for them are averaged. As mentioned above
Since the first and second bits in the horizontal direction of the channel data, or the fourth and fifth bits have the same value, these frequency characteristics are also the same in this figure. In this figure, for comparison, the same original data is output by the encoding method that does not function to suppress the vertical DC component and low frequency component using the encoding table of FIG. The frequency characteristics of the channel data are also shown. In the channel data thus generated, the low frequency component in the vertical direction is suppressed as shown in FIG. It will be appreciated that there is an advantage to the channel data thus generated.

Note that FIG. 1 shown in the analysis result of FIG.
In the third embodiment of the encoding method of the present invention, which functions to suppress the direct current component and the low frequency component in the vertical direction using the encoding table of No. 5, specifically, the encoding table can be output. When there is only one type of channel data, step 4 (channel data output step) outputs the channel data. If the encoding table is capable of outputting a plurality of types of channel data, step 3 (appropriate channel data selection step) is performed on the following 8 bits of original data by following 8 bits in the vertical direction × 3 bits in the horizontal direction (first 1
(2nd bit to 4th bit excluding 5th bit and 5th bit) are foreseen (when the following original data is less than 8 bits, all the following channel data are foreseen). Then, the channel data in the case where 0 is set to −1 and 1 is set to 1 up to the foreseeable range for each bit position in the horizontal direction is vertically accumulated, and the channel whose absolute value is the maximum is the minimum. Select data. Then step 4
In the (channel data output step), the channel data thus selected is output. The third embodiment of the encoding method of the present invention has been described above.

Next, an embodiment of the encoding circuit of the present invention will be described. FIG. 17 shows a first encoding circuit of the present invention.
3 is a block diagram showing the configuration of the embodiment of FIG. The encoding circuit 1701 includes an encoding table 1702.
The coding table 1702 has the states of the coding table itself, such as the coding table of FIG. 1, as an input and an output. That is, this encoding circuit 1701
Is a coding circuit corresponding to a coding table having the states of the coding table itself at the input and the output. The coding table described in the above-described coding method of the present invention is
Generally, a lookup table (lookup table)
It will be appreciated that it can easily be implemented in circuits such as e) or ROM. Further, it is understood that the encoding circuit corresponding to the above-described encoding method of the present invention can be easily implemented like this encoding circuit 1701 and functions as described in the above-mentioned encoding method of the present invention. See.

FIG. 18 shows the second encoding circuit of the present invention.
3 is a block diagram showing the configuration of the embodiment of FIG. The encoding circuit 1801 includes an encoding table 1802.
This encoding table 1802 does not have the state of the encoding table itself in either input or output. That is, this encoding circuit 1801 is an encoding circuit corresponding to an encoding table having neither the state of the encoding table itself nor the state of the encoding table itself. It will be appreciated that the encoding circuit 1801 and the encoding table 1802 are also easy to implement and function as described in the encoding method of the invention above.

In addition to these, the third embodiment of the encoding method of the present invention corresponds to the case where the subsequent channel data is foreseen and an appropriate one of a plurality of types of selectable channel data is selected. It goes without saying that such an encoding circuit can be easily implemented. Briefly, an encoding table, a part that temporarily stores a plurality of types of selectable channel data, a part that looks ahead to the subsequent channel data to determine whether it is appropriate, and one channel that is appropriate Such a coding circuit can be implemented by providing a part for selecting data. The encoding circuit of the present invention has been described above.

Next, a first embodiment of the recording method of the present invention will be described. This consists of the following two steps, Step 1 and Step 2. Step 1 (channel data generation step): Channel data having a finite number of bits that satisfies a predetermined constraint when arranged two-dimensionally with respect to the original data having a finite number of bits is generated. Step 2 (channel data recording step):
Data is recorded in a finite area of the storage medium according to the two-dimensional arrangement.

FIG. 19 is a diagram showing a storage medium in which channel data is recorded according to the first embodiment of the recording method of the present invention, and is a diagram showing the first embodiment of the storage medium of the present invention. is there. In this figure, the first embodiment of the recording method of the present invention uses an optical disc 190 as a storage medium.
An example using 1 is shown. Also, in this figure, the first embodiment of the recording method of the present invention shows an example in which the channel data of FIG. 2 is generated in step 1 (channel data generation step). In this figure, the area 1912 is an enlarged view of the minute area 1911 of the optical disk 1901.

The general recording apparatus recognizes the position of the storage medium on which the target channel data should be recorded (and reproduced). This is, for example, from the host when it is used as a secondary storage of data handled by the host (computer) and from the host when it is used to store AV data of digitized sound or video. From the part that controls the AV data and compresses the information (the part that controls the channel constraint code, the error correction code, etc. is sometimes called the front end part, while this is sometimes called the back end part), Recording device (or its front end,
Hereinafter, this description will be omitted) receives the logical data to be recorded in the storage medium and the logical address thereof. The recording device that has received the logical address recognizes the physical address (information indicating the position of the storage medium) where the data should be recorded, from the logical address.

In the example of FIG. 19, the channel data of FIG. 2 is recorded in the finite area 1921 shown by the thick dotted line.
Around the finite area 1921 indicated by the thick dotted line, there is another area indicated by the thick dotted line, which is an area for storing other channel data (and thus original data and logical data). In addition, between each storage area, a pad (PAD), a guard band (Guard Band), a space (sp)
There is a blank area 1922 in which data should not be recorded. It should be noted that the thick and thin dotted lines shown in FIG. 19 respectively show the finite area on the storage medium and the bits of the channel data for easy understanding, and are not visible in the actual storage medium. is there.

The channel data of FIG. 2 recorded in the finite area 1921 indicated by the thick dotted line is such that the logical vertical direction shown in FIG. 2 is the physical circumference (tangential line) direction of the optical disk and the logical horizontal direction is the physical direction. The logical polarities such as space (white) for the value 0 of each bit of the channel data, and mark (gray) for the value 1 of each bit of the channel data. The physical polarity difference was assigned and recorded. For example, the bit value 1 of the channel data in the first row and first column of FIG. 2 is represented by the mark 1931 in FIG. 19, and the bit value 0 of the channel data in the sixth row and first column of FIG. It is recorded as 19 spaces 1932. This physical difference in polarity is carried out depending on whether or not there are pits (holes) in the optical disc, and whether the state of the substance of the memory film is crystalline or amorphous (amorphous). Here, although the logical vertical direction and the horizontal direction are assigned to the physical circumferential direction and the radial direction, respectively, the present invention can be carried out other than this if the physical directions are different.
Further, it goes without saying that the difference between the logical polarity and the physical polarity of the channel data can be implemented in addition to the above.

The first embodiment of the recording method of the present invention is as follows:
In step 2 (channel data recording step),
The recording beam is applied to each bit of the channel data of FIG. 2 to each bit of the physical channel data on the optical disk shown by the thin dotted line in the finite area 1921 shown by the thick dotted line of FIG. (Stamper, stan
per) to record.

When recording is performed using the imprinting mechanism, each bit of those channel data is recorded simultaneously. On the other hand, when recording is performed using the recording beam, the recording order of each bit of the channel data can be performed in any manner, but considering that the optical disc is rotating, Since the position relatively moves in the circumferential direction on the rotating optical disc, it is sufficient to record in order in the circumferential direction. Then, a single bit may be recorded in the radial direction of the channel data using a single recording beam, and adjacent bits may be recorded in the radial direction of the channel data when the optical disk makes one rotation. However, a plurality of bits of channel data may be recorded in parallel in the radial direction using a plurality of recording beams. If there is a time lag between the generation of each bit of the channel data in step 1 and the recording in step 2, if there is a portion (semiconductor memory such as DRAM) for storing the data, that portion Channel data may be temporarily stored in.

Although an example in which an optical disk is used as a storage medium has been described with reference to FIG. 19, any other storage medium having a finite size capable of storing two-dimensionally may be used. Such storage media include, for example, magnetic disks, magneto-optical disks, magnetic tapes, magnetic drums, magnetic cards,
There are optical cards and semiconductor memories. More specifically,
For example, even a magnetic disk has a storage medium of a longitudinal magnetic recording system (horizontal magnetic recording system), a vertical magnetic recording system, or the like, but is applicable to any storage medium.

Further, not limited to the example of FIG. 19, for example, in recording / reproducing, for use in recording / reproducing positioning processing (servo processing, etc.) performed by the storage device, a physical area in the blank area 1922 of the storage medium is used. It is also possible to embed information such as addresses that can be used for positioning and the like. Further, although the bit positions in the physical diameter (logical lateral) direction of the channel data have the same bit pitch in FIG. 19, they can be implemented differently. For example, the bit position at the end in the physical diameter (logical lateral) direction in each finite area may be set larger or smaller than the other bit positions.

In FIG. 19, the length (the number of bits) of the channel data existing in one finite area is in both the physical circumferential (logical vertical) direction and the physical diameter (logical horizontal) direction. The reason why it is relatively short is to facilitate understanding.
As described above, the channel constraint code having a larger number of logical bits in the horizontal direction is more advantageous from the viewpoint of storage capacity. In addition, from the perspective of reducing the ratio of areas where original data is not stored, such as blank areas, the physical circumference (logical vertical) direction and physical diameter (logical horizontal)
It goes without saying that it is advantageous from the viewpoint of storage capacity that bits are continuous in both directions. The first embodiment of the recording method of the present invention has been described above.

Next, a second embodiment of the recording method of the present invention will be described. This consists of the following three steps, Step 1 to Step 3. Step 1 (first channel data generation step): For the original data having a finite number of bits, the first channel data having a finite number of bits that satisfies a predetermined constraint when arranged two-dimensionally is generated. Step 2 (channel control data adding step): Finite bits that satisfy predetermined constraints when two-dimensionally arranged by adding channel control data used for reproduction to predetermined portions of the first channel data. Generate a number of second channel data. Step 3 (second channel data recording step): The second channel data is recorded in a finite area of the storage medium according to the two-dimensional arrangement.

FIG. 20 is a diagram showing a storage medium in which channel data is recorded according to the second embodiment of the recording method of the present invention, and is a diagram showing the second embodiment of the storage medium of the present invention. is there. In this figure, the second embodiment of the recording method of the present invention is a recording medium in which a groove (Gro) is used.
An example using an optical disc 2001 composed of an ove, a groove, a guide groove) and a land (Land, non-groove) is shown (an optical disc having a land and a groove is in a conventional technique).

In this figure, the second embodiment of the recording method of the present invention is an example in which channel data is generated using the encoding table of FIG. 15 in step 1 (first channel data generation step). Is shown. In this figure, the area 2012 is an enlarged view of the minute area 2011 of the optical disc 2001.

In the example of FIG. 20, channel data of 6 bits in the vertical direction × 5 bits in the horizontal direction are generated in step 1, and the channel data is shown by the continuous three types of thick dotted lines in the groove portion 2021. Finite area 204
Among the items 1 to 2043, the data is recorded in the limited area 2042. Around these areas, there are other areas indicated by thick dotted lines in the same groove portion 2021, the groove portion 2024 and the groove portion 2025 beyond the land portion 2022 and the land portion 2023, but there are other areas. This is an area for storing the channel data of. Further, a blank area 2031 in which data should not be recorded exists between the storage areas existing in the same groove portion.

The second embodiment of the recording method of the present invention is as follows:
In step 2 (channel control data addition step), channel control data is added to the first channel data to be generated in step 1. Specifically, in order to enable the reproducing apparatus to synchronize with the bits of the channel data on the storage medium during reproduction, in the example of FIG. 20, 8 bits in the vertical (circumferential) direction in the finite area 2041 ×
An appropriate predetermined pattern of 5 bits in the lateral (diameter) direction is added. In order to satisfy the predetermined constraint (minimum run length 2) between this pattern and the first channel data, for example, for this pattern and the encoding table of FIG. In the generation, the first horizontal bit of the channel data to be preset is set to 0, and the state of the coding table itself to be preset is set to Q0.

Further, with respect to the first channel data generated in this way, the encoding used to satisfy a predetermined constraint at the end of the first channel data (the lower end in the vertical direction and its vicinity), or the encoding used Depending on the configuration of the table, even at the end of the first channel data, the end corresponding to the end of the first channel data can be uniquely decoded by the decoding method of the present invention to be described later. Add a pattern. Specifically, FIG.
In the above example, as a pattern corresponding to the first channel data in the finite area 2042, a predetermined termination pattern of 1 bit in the vertical (circumferential) direction × 5 bits in the horizontal (diameter) direction in the finite area 2042 is added. The second channel data is obtained by adding the channel control data for controlling such channel data.

In the second embodiment of the recording method of the present invention, the second channel data generated in this way is indicated by three continuous types of thick dotted lines in step 3 (channel data recording step). The data is recorded in the area 2041, the limited area 2042, and the limited area 2043. Specifically, in the finite area 2041, the channel control data of 8 bits in the vertical (circumferential) direction × 5 bits in the horizontal (radial) direction added in step 2 is stored in the finite area 2042 in step 1
In the finite area 2043, the first channel data generated in (1) is recorded with channel control data of 1 bit in the vertical (circumferential) direction × 5 bits in the horizontal (radial) direction added in step 2. As shown in FIG. 20, the second channel data continuously recorded on the storage medium satisfies the minimum run length 2 given to the channel data generated by the encoding table of FIG. 15 in both the vertical and horizontal directions. You will understand.

Note that in FIG. 19, the mark is shown as a circle or an expanded form of a circle at the bit value 1 of the channel data, whereas in FIG. 20, it is shown as a quadrangle. This is because the aspect of the channel data stored in the storage medium is not limited to the state and shape of the substance described in FIG.
It means that the present invention can be applied to aspects other than these. In a recording device using an optical disc, it is generally more difficult to draw a square mark as a bit of channel data on a storage medium than a circular mark, but the wavelength of the recording beam and the focus By using a lens or one suitable for the material of the storage medium, the recording device will be able to delicately draw, and if the position of the spot of the recording beam is properly controlled, a square mark (or a shape close to it) Can be drawn.

Further, in step 2, the pattern for bit synchronization and the termination pattern are added, but only one of them or the channel control data for controlling the channel data other than these is added. Good. The channel control data other than these is, for example, a pattern (symbol, byte) for enabling the reproducing device (or the decoding circuit) to recognize (synchronize) the correspondence between the channel data and the original data during reproduction. A pattern for synchronization, a tracking pattern for use in servo processing or tracking that allows the playback device (or decoding circuit) to recognize the radial position on the storage medium during playback, and during playback There is a pattern or the like indicating information such as a logical address and a physical address for the reproducing apparatus (or the decoding circuit) to recognize whether or not the area of the storage medium currently being reproduced is correct. If these channel control data are added, it is necessary to configure these channel control data patterns so that these patterns themselves also satisfy the predetermined constraints and also satisfy the predetermined constraints with other consecutive patterns. Good.

Further, in the above description, one kind of finite bit number of channel data for one kind of finite bit number of original data is provided as a continuous finite area (a finite area 1921 indicated by a thick dotted line in FIG. 19, and a thick area in FIG. 20). It is recorded in the finite areas 2041 to 2043) indicated by the dotted line and is recorded so as to be separated from the channel data for other original data in a blank area, but it can be implemented in addition to this. For example,
It is also possible to continuously record the plural types of finite bit number of channel data with respect to the plural types of finite bit number of original data. Then, it is also possible to add, for example, a termination pattern and a pattern for pattern synchronization between each finite number of bits of channel data.

Further, as shown in FIG. 20, the channel data is not stored only in the groove portion, but the land portion is made to have a sufficient width so that the channel data is also stored in the land portion. It goes without saying that you can also do it. The second embodiment of the recording method of the present invention has been described above.

Next, an embodiment of the recording apparatus of the present invention will be described. FIG. 21 is a block diagram showing the configuration of the first embodiment of the recording / reproducing apparatus of the present invention, which uses an optical disc as a storage medium. FIG. 21 shows the function of not only recording but also reproducing, for use in the description of the reproducing apparatus of the present invention described later. The optical disk device 2101 of FIG. 21 uses an optical disk 2118 as a storage medium, and is a storage device that is connected to the host 2102 and stores the data.

The optical disk device 2101 is a host 210.
Interface unit 211 for interfacing with 2
1. A bus control unit 2112 that arbitrates a data bus so that data can be transferred between appropriate parts, a memory 2113 that plays a role of a cache or a buffer and stores work data, an error correction encoding and An error correction coding / decoding unit 2114 that performs the decoding (error correction), a coding method (or a circuit thereof) of the present invention described above that performs channel constraint coding and its decoding, and a decoding method of the present invention described later (or that (A circuit) embodying a constraint encoding / decoding section 2115, a signal processing section 2116 for generating a recording signal and a signal processing of a reproduction signal, an optical disk 211.
8 is composed of an optical head 2117 for transferring (recording and reproducing) data to and from the optical disc 8, a processor 2119 for controlling the entire inside of the optical disc device 2101, a spindle motor (not shown) for rotating the optical disc, and the like. The optical head is composed of a laser pickup 2121 for generating a light beam and detecting reproduction light, a lens 2122 for condensing light from the laser pickup and reproduction light, and the like.

The interface unit 2111 is used by the host 21.
Logical data (and logical address) to be recorded from 02
When the data is received, the data is stored in the memory 2113 via the bus control unit 2112 (hereinafter, this description will be omitted). Next, the memory 2113 sends the stored logical data to the error correction coding / decoding unit 2114, and the error correction coding / decoding unit 2114 generates redundant data for the data and stores the result in the memory 2113. Store. The combination of logical data and redundant data is the original data that is the target of the encoding method of the present invention.

Next, when the optical head 2117 is ready to access the target finite area 2131 (corresponding to the logical address) of the optical disk 2118 rotated by a spindle motor (not shown), the memory 21
Reference numeral 13 denotes the original data stored in the constraint encoding / decoding unit 21.
15, the constraint coding / decoding unit 2115 converts the original data into channel data by the above-described coding method (or circuit thereof) of the present invention, and sends the channel data to the signal processing unit 2116.

Next, the signal processor 2116 sends the recording signal generated for the data to the laser pickup 2121 in the optical head 2117, and the lens 2122 collects the recording beam emitted by the laser pickup 2121. Optical disk 2118
Finite area 21 of the target (corresponding to the logical address) of
Record at 31. Thus, the optical disk device 2101
The data to be recorded received from the host 2102 is recorded on the optical disc 2118. This optical disk device 2101
Since a single recording beam is used, channel data having multiple bits in the radial direction is recorded by recording a single bit in the radial direction and consecutive bits in the circumferential direction are recorded continuously. When the optical disk 2118 makes one rotation, the adjacent bit is recorded in the radial direction.

FIG. 22 is a block diagram showing the configuration of the second embodiment of the recording / reproducing apparatus of the present invention, which uses an optical disk as the storage medium. Optical disk device 220 of FIG.
1 is different from the optical disk device 2101 of FIG. 21 in that the optical head 2117 is changed to an optical head 2217. The optical head 2217 includes a laser pickup 2221 that generates a plurality of light beams and detects a plurality of reproduction lights, a lens 2222 that collects a plurality of lights from the laser pickup and a plurality of reproduction lights, and the like. Since this optical disc device 2201 uses a plurality of recording beams, channel data having a plurality of bits in the radial direction is recorded in parallel in the radial direction by the plurality of recording beams. The embodiment of the recording apparatus of the present invention has been described above.

In the present invention, not only the storage medium suitable for the encoding method (and its circuit) and the recording method (and its apparatus) but also the storage medium for storing the channel data recorded by the recording method of the present invention. Simplex (eg, Figure 1
9 and FIG. 20), it will be understood that the effects of the present invention can be obtained. That is, not only a magnetic disk device such as a magnetic disk device having a storage medium and a drive mechanism combined but also a C
It is understood that the effects of the present invention can be obtained even with a storage medium used in a storage device that can be replaced by another storage medium such as an optical disc device using an optical disc called D or DVD. Will be done.

Next, an embodiment of the reproducing method of the present invention will be described. This consists of the following two steps, Step 1 and Step 2. Step 1 (channel data reproducing step): Channel data having a finite number of bits is reproduced from a finite area of the storage medium. Step 2 (original data restoration step): The original data of a finite number of bits is restored to the channel data.

FIG. 23 is a diagram showing the storage medium of FIG. 19 reproduced by the embodiment of the reproducing method of the present invention.
This figure is different from FIG. 19 in that a reproduction spot 2301 is present. In FIG. 23, it is assumed that a single reproduction beam is used to reproduce a single bit in the radial direction of the channel data, and when the optical disc makes one rotation, the adjacent bit is reproduced in the radial direction of the channel data. There is.
FIG. 24 is a diagram showing the storage medium of FIG. 20 reproduced by the embodiment of the reproducing method of the present invention.

This figure is different from FIG. 20 in that reproduction spots 2401 to 2405 are present. Figure 24
In the above, the channel data having a width of 5 bits existing in the radial direction is reproduced in parallel by using five reproduction beams. If a time lag occurs after the reproduction signal is detected by scanning as described above and before the step of reproducing channel data that is a binary sequence in step 1 or the restoration of the original data in step 2 occurs. A portion for storing data (semiconductor memory such as DRAM) may be provided, and the reproduced signal or the reproduced channel data may be temporarily stored in the portion.

In step 1, after the reproduction signal is detected as described above, if necessary, signal processing (waveform equalization (equal)
alignment) and thresholds (threshold, thre
hold, level) determination (so-called slice), or maximum likelihood (ML, Maximum Likelilihoo)
d) Judgment or the like) is performed to reproduce the finite number of bits of channel data that is a binary sequence. Since the embodiment of the storage medium of the present invention stores the channel data two-dimensionally, it can be said that performing the signal processing two-dimensionally is effective from the viewpoint of reliability. In this way, in step 1 (channel data reproducing step), the channel data stored in the storage medium is detected as a reproduced signal, and signal processing is performed on the detected channel data to obtain a finite number of bits that is a binary sequence. Play the channel data of.

Step 2 (original data restoration step) is
The finite number of bits of channel data reproduced in step 1 is sent to the decoding method (or its circuit) of the present invention described later for each predetermined number of bits, thereby obtaining the finite number of bits of original data. Here, the number of bits of the channel data sequentially generated by the encoding method (or its circuit) performed at the time of recording is 1 in the vertical direction as in the first embodiment of the encoding method of the present invention described above. In the case of 4 bits × horizontal direction 4 bits, the decoding method (or its circuit) of the present invention
The data is sent every predetermined number of bits, for example, every 1 bit in the vertical direction x every 4 bits in the horizontal direction, or every 2 bits in the vertical direction x every 4 bits in the horizontal direction. At this time, if the channel data on the storage medium includes channel control data for use in synchronization, servo, tracking, etc. during reproduction, the decoding method (or its circuit) ) Will not be sent to. On the other hand, among the channel control data, if the termination pattern is added to enable unique decoding to the original data, the data is sent to the decoding method (or its circuit).

When the optical disc having the groove portion and the land portion shown in FIG. 24 is used, it is generally necessary to detect the difference between the reproduced signals from the groove portion and the land portion to detect the difference between the reproduced signal between the mark and the space. It can be easier than doing. In such a case, among the reproduction spots 2401 to 2405, the land portion 2022 is included.
Also, the reproduction spot 2401 and the reproduction spot 2405, which are respectively close to the land portion 2023, may be used particularly for tracking. The embodiment of the reproducing method of the present invention has been described above.

Next, an embodiment of the reproducing apparatus of the present invention will be described. In FIG. 21, the optical disk device 21
The interface unit 2111 in 01 is connected to the host 2102.
Receives the logical address to be reproduced. Optical disk 21 rotated by a spindle motor (not shown)
When the optical head 2117 is ready to access the target finite area 2131 (corresponding to the logical address) of 18, the laser pickup 2121 in the optical head 2117 first outputs the reproduction beam through the lens 2122 to the optical disk 2118. Of the laser beam from the reproduction light obtained through the lens 2122 by irradiating the target finite area 2131 (corresponding to the logical address) of
21 detects a reproduced signal. The optical head 2117 sends the reproduction signal to the signal processing unit 2115, and the signal processing unit 211
5 reproduces the binary series channel data by performing signal processing on the reproduced signal.

Next, the constraint coding / decoding section 2115 restores the original data from the channel data by the decoding method (or its circuit) of the present invention described later, and stores the result in the memory 2113. Next, the memory 2113
Is an error correction coding / decoding unit 21 for the stored original data.
14 and the error correction coding / decoding unit 2114 performs error correction on the data (decoding for error correction coding).
Then, the erroneous data in the memory 2113 is corrected.
Next, the data stored in the memory 2113 is sent to the host 2102 as logical data to be reproduced. In this way, the optical disk device 2101 reproduces, from the optical disk 2118, the logical data corresponding to the logical address to be reproduced received from the host 2102, and the host 2102.
Send to. Since this optical disc device 2101 uses a single reproduction beam, it reproduces channel data having a plurality of bits in the radial direction and a single bit in the radial direction,
Bits continuous in the circumferential direction are continuously recorded, and when the optical disk 2118 makes one rotation, the adjacent bits are recorded in the radial direction.

In FIG. 22, this optical disk device 2
Since 201 uses a plurality of reproduction beams, channel data having a plurality of bits in the radial direction is reproduced in parallel in the radial direction by the plurality of reproduction beams. The embodiment of the reproducing apparatus of the present invention has been described above.

Next, embodiments of the decoding method and its circuit of the present invention will be described. The embodiment of the decoding method of the present invention comprises the following two steps, step 1 and step 2. Step 1 (decoding table input step): The channel data having a finite number of bits, which is sequentially input for each predetermined number of bits, is input to a decoding table which is configured in advance. Step 2 (original data combining step): The original data output from the decoding table is combined with the sequential input of the channel data.

In any of the embodiments of the above-described encoding method of the present invention, the channel data of an arbitrary predetermined number of consecutive bits (which is output at the transition of a predetermined time point in the encoding graph) generated by the encoding method is generated. On the other hand, the corresponding original data (the second label of the transition in the encoding graph) uses an encoding table that is uniquely determined. Therefore, the original data can be uniquely decoded (inverse conversion to the channel constraint coding) by observing the channel data of the predetermined number of bits at the maximum.

Depending on the configuration of the encoding table used, it may not be possible to decode the end of the channel data encoded from the original data (logical lower end in the vertical direction and its vicinity) into the original data. . However,
Even in such a case, in order to enable the second embodiment of the recording method of the present invention described above to uniquely decode such data into original data, a termination pattern is added. Therefore, if the end pattern is observed, such data can be uniquely decoded into original data.

Therefore, a decoding table corresponding to the coding table for coding the original data into the channel data and capable of decoding the input of the channel data of a predetermined number of bits (without error) without fail to the original data It will be appreciated that can be configured. It is possible that the channel data will be incorrect after passing through the channel, but in such a case,
When the decoding table recognizes the presence of an error (cannot be decoded), it outputs a flag indicating that it is incorrect, or outputs data that may not be accurate as original data corresponding to that channel data, And so on. Even in such cases,
Incorrect original data may be restored by corrective error correction performed later in the reproducing method (or the apparatus thereof).

For example, an embodiment of a decoding method of the present invention corresponding to the above-described first embodiment of the encoding method of the present invention for sequentially outputting channel data of 1 bit in the vertical direction × 4 bits in the horizontal direction. In step 1 (decoding table input step), input channel data, which is sequentially input, for example, every 1 bit in the vertical direction x 4 bits in the horizontal direction or every 2 bits in the vertical direction x 4 bits in the horizontal direction into the decoding table. To do. If a termination pattern is added in order to uniquely decode the original data, the termination pattern is also input to the decoding table.

In the reproducing method (or the apparatus therefor), error correction for the original data and transfer of the original data to the host or the like are performed thereafter. Some or all of the data needs to be prepared. Further, if there is a speed difference between the data transfer from the storage medium to the playback device and the data transfer from the playback device to the host, etc., the storage device buffers the data in order to buffer it. It is necessary to prepare a part or all of the target finite number of original data having a part for temporarily storing the data.

According to the embodiment of the decoding method of the present invention, in step 2 (original data combining step), the original data generated in step 1 is a part (temporarily storing data which plays a role of a cache or a buffer). DRAM
Etc.) to the semiconductor memory, etc.), and the part stores the original data. This is because, in step 1 of the first embodiment of the above-described encoding method of the present invention, the part stores the original data, and the stored original data is encoded table every predetermined number of bits. By sending the original data to each predetermined number of bits, the reverse connection is performed.

It goes without saying that, like the embodiment of the circuit corresponding to the encoding method of the present invention described above, the embodiment of the circuit corresponding to the decoding method of the present invention can be easily implemented. . Briefly, the decoding table may be implemented by a circuit called a look-up table. In addition, if the channel data that is sequentially input for each predetermined number of bits cannot be sequentially decoded into the original data and it is necessary to observe the predetermined number of bits,
Holds such channel data by having a part that temporarily stores the data and has a size sufficient to hold the channel data that is sequentially input even while observing until unique decoding is possible. You can do it. The embodiments of the decoding method and the circuit thereof according to the present invention have been described above.

It will be understood that, according to the present invention, the density of the channel constraint code can be increased (the information amount of the original data allocated to the unit area of the storage medium can be increased) as compared with a general storage device. Further, the present invention is
A magnetic disk device, an optical disk device, a magneto-optical disk device, a magnetic tape device, a magnetic drum device, a magnetic card device, an optical card device, a semiconductor memory, and the like, which use a storage medium of a finite size that can be two-dimensionally stored. It will be appreciated that it can be implemented in an actual storage device.

[0140]

As compared with the general storage device, the density of the channel constraint code can be increased (the information amount of the original data assigned to the unit area of the storage medium can be increased).
Furthermore, a magnetic disk device, an optical disk device, a magneto-optical disk device, a magnetic tape device, a magnetic drum device, a magnetic card device, an optical card device, and a semiconductor memory using a storage medium of a finite size that can be two-dimensionally stored. Etc.
It can be implemented in an actual storage device.

[0141]

[Brief description of drawings]

FIG. 1 is a diagram showing an encoding table used in a first embodiment of an encoding method of the present invention.

FIG. 2 is a diagram showing channel data generated by the first embodiment of the encoding method of the present invention.

FIG. 3 is a diagram showing state transitions used to configure the encoding table of FIG. 1 in the first embodiment of the encoding method of the present invention.

FIG. 4 is a diagram showing a transition matrix of the state transition of FIG. 3 in the first embodiment of the encoding method of the present invention.

FIG. 5 is a diagram showing a state transition obtained by modifying the state transition of FIG. 3 in the first embodiment of the encoding method of the present invention.

FIG. 6 is a diagram showing a state transition in which a label is assigned to the state transition of FIG. 5 in the first embodiment of the encoding method of the present invention.

FIG. 7 is a diagram showing Shannon capacities that can be derived in the process of configuring the coding table in the first embodiment of the coding method of the present invention.

FIG. 8 is a first diagram showing a generation order of channel data generated according to the first embodiment of the encoding method of the present invention.

FIG. 9 is a second diagram showing a generation order of channel data generated according to the first embodiment of the encoding method of the present invention.

FIG. 10 is a third diagram showing a generation order of channel data generated according to the first embodiment of the encoding method of the present invention.

FIG. 11 is a diagram showing state transitions used to configure an encoding table in the second embodiment of the encoding method of the present invention.

FIG. 12 is a diagram showing a state transition in which a label is assigned by modifying the state transition of FIG. 7 in the second embodiment of the encoding method of the present invention.

FIG. 13 is a diagram showing an encoding table used in the second embodiment of the encoding method of the present invention.

FIG. 14 is a diagram showing relative channel data, first channel data, and second channel data generated by the second embodiment of the encoding method of the present invention.

FIG. 15 is a diagram showing an encoding table used in the third embodiment of the encoding method of the present invention.

16 is a diagram showing frequency characteristics of channel data generated by the third embodiment of the encoding method of the present invention using the encoding table of FIG.

FIG. 17 is a block diagram showing a configuration of a first embodiment of an encoding circuit of the present invention.

FIG. 18 is a block diagram showing a configuration of a second embodiment of an encoding circuit of the present invention.

FIG. 19 is a diagram showing a first embodiment of a storage medium of the present invention.

FIG. 20 is a diagram showing a second embodiment of a storage medium of the present invention.

FIG. 21 is a block diagram showing the configuration of the first embodiment of a storage / reproduction device of the present invention.

FIG. 22 is a block diagram showing the configuration of a second embodiment of a storage / reproduction device of the present invention.

23 is a diagram showing the storage medium of FIG. 19 reproduced by the embodiment of the reproducing method of the present invention.

FIG. 24 is a diagram showing the storage medium of FIG. 20 reproduced by the embodiment of the reproducing method of the present invention.

FIG. 25 is a first diagram showing the positional relationship of pits in the known optical disc recording medium of the third document.

FIG. 26 is a second diagram showing the positional relationship of pits in the known optical disc recording medium of the third document.

FIG. 27 is a third diagram showing the positional relationship of pits in the optical disc recording medium of the known third document.

[Explanation of symbols]

1701, 1801 ... Encoding circuit 1702, 1802 ... Encoding table 1901, 2001, 2118 ... Optical disc 2101, 201 ... Optical disc device

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yukari Katayama             1099 Ozenji, Aso-ku, Kawasaki City, Kanagawa Prefecture             Ceremony company Hitachi Systems Development Laboratory (72) Inventor Takashi Nishitani             1099 Ozenji, Aso-ku, Kawasaki City, Kanagawa Prefecture             Ceremony company Hitachi Systems Development Laboratory (72) Inventor Takeshi Maeda             1-280, Higashikoigakubo, Kokubunji, Tokyo             Central Research Laboratory, Hitachi, Ltd. F-term (reference) 5D044 BC01 BC02 BC10 CC09 GL01                       GL02

Claims (9)

[Claims] 1. A step of generating channel data having a finite number of bits to be stored in a finite area of a storage medium, which satisfies a predetermined constraint when arranged two-dimensionally with respect to original data having a finite number of bits. An encoding method having. 2. A means for generating channel data having a finite number of bits to be stored in a finite area of a storage medium, which satisfies a predetermined constraint when arranged two-dimensionally with respect to the original data having a finite number of bits. An encoding circuit having. 3. A decoding method comprising a step of decoding channel data having a finite number of bits that satisfies a predetermined constraint when arranged two-dimensionally into original data having a finite number of bits. 4. A decoding circuit having means for decoding channel data having a finite number of bits satisfying a predetermined constraint when arranged two-dimensionally into original data having a finite number of bits. 5. A recording method comprising the step of recording channel data having a finite number of bits satisfying a predetermined constraint when arranged in a two-dimensional manner in a finite area of a storage medium according to the two-dimensional arrangement. Method. 6. A recording device comprising means for recording channel data having a finite number of bits satisfying a predetermined constraint when arranged two-dimensionally in a finite area of a storage medium according to the two-dimensional arrangement. apparatus. 7. A reproducing method comprising reproducing channel data having a finite number of bits satisfying a predetermined constraint when the channel data is arranged two-dimensionally from a finite area of a storage medium. 8. A reproducing apparatus comprising a step of reproducing, from a finite area of a storage medium, channel data having a finite number of bits satisfying a predetermined constraint when arranged two-dimensionally. 9. A storage medium, wherein channel data having a finite number of bits satisfying a predetermined constraint when arranged two-dimensionally is stored in the finite area.