Coded data generation or conversion – Digital code to digital code converters
Reexamination Certificate
1999-10-18
2002-04-16
JeanPierre, Peguy (Department: 2819)
Coded data generation or conversion
Digital code to digital code converters
C341S050000
Reexamination Certificate
active
06373405
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a conversion method employed to convert sequentially information blocks, each of which is extracted sequentially from information sequence and acts as a conversion unit, into code blocks. More particularly, the present invention relates to a conversion method and a conversion device which are capable of converting the information blocks into the code blocks through simple procedures, while taking account of suppression of a direct current component.
The present invention also relates to a restoration method and a restoration device which are optimal to restore the code blocks, which are converted by using the above conversion method, to original information blocks.
2. Description of the Prior Art
In the prior art, in order to remove defects such as restoration error caused due to baseline shift, etc. when information blocks each of which is extracted sequentially from information sequence and acts as a conversion unit are converted sequentially into code blocks, various conversion methods have been known which intend to realize the conversion taking account of suppression of a direct current component.
For example, in Patent Application Publication (KOKAI) Sho 59-200562, a conversion method has been disclosed which intends to realize the conversion while taking suppression of the direct current component into consideration. According to this conversion method, when 8-bit information blocks are converted into 10 bit code blocks, codes in which “1” and “0” are equal or close in number to each other are selected as a code conversion candidate from codes of 2
10
=1024 patterns, and then the selected code conversion candidates are allocated to the codes of 2
8
=256 patterns so as to correlate the code conversion candidates with the codes respectively.
Also, for example, in Patent Application Publication (KOKAI) Sho 60-107921, another conversion method has been disclosed which intends to realize the conversion while considering suppression of the direct current component. According to this conversion method, codes with the small bit number are converted into codes with the large bit number, then codes which do not contain the direct current component and which have patterns whose change points of information level are separated by more than two bits, codes which have patterns in which change points of information level are separated by more than two bits but the net positive or negative direct current component is suppressed within the previously determined range, or the like are selected as the code conversion candidate from the latter codes with the large bit number, and then a plurality of selected code conversion candidates are allocated to the codes with the small bit number so as to correlate the code conversion candidates with the codes respectively.
However, such a problem to be solved exists in the above conversion methods in the prior art that procedures required for converting the information blocks into the code blocks while taking account of suppression of the direct current component become complicated.
In other words, according to the conversion method disclosed in Patent Application Publication (KOKAI) Sho 59-200562, because only 193 codes in which “1” and “0” are contained equally in number are present in the codes of 2
10
=1024 patterns, 63 patterns of the codes in which “1” and “0” are close in number must also be selected as the code conversion candidate. In this case, further the procedure of compensating difference between “1” and “0” is requested.
As a result, the procedures required to convert the information blocks into the code blocks with considering the suppression of the direct current component become complicated.
In contrast, according to the conversion method disclosed in Patent Application Publication (KOKAI) Sho 60-107921, patterns in which the change points of information level are separated by more than two bits but the net positive or negative direct current component is suppressed within the previously determined range are selected as the code conversion candidate. In this case, the procedure of eliminating the net positive or negative direct current component is further requested. As a result, the procedures required to convert the information blocks into the code blocks with considering the suppression of the direct current component become complicated.
Therefore, interested persons earnestly look forward to development of a new technology which are capable of converting the information blocks into the code blocks through simple procedures while taking account of suppression of the direct current component.
SUMMARY OF THE INVENTION
The present invention has been made in light of the above circumstances and it is an object of the present invention to provide a conversion method and a conversion device which are capable of converting information blocks into code blocks through simple procedures, while taking account of suppression of a direct current component, by dividing information blocks, each of which is extracted sequentially from information sequence and acts as a conversion unit, into a plurality of original subblocks, then generating inverted subblocks containing inverted information, which are obtained by inverting all original information allocated to one or more segments contained in divided original subblocks, while correlating the original subblocks with the inverted subblocks respectively, and then combining together a plurality of original subblocks and a plurality of generated inverted subblocks.
It is another object of the present invention to provide a restoration method and a restoration device which are optimal to restore the code blocks, which are converted by using the above conversion method, to original information blocks.
In order to achieve the above object, there is provided a conversion method of converting sequentially information blocks, each of which is extracted sequentially from an information sequence and acts as a conversion unit, into code blocks, the method comprising the steps of: dividing the information blocks into a plurality of original subblocks; generating a plurality of inverted subblocks containing inverted information, which are obtained by inverting all original information being allocated to one or more segments contained in original subblocks, while correlating the original subblocks with the inverted subblocks respectively; and converting the information blocks into the code blocks by combining the plurality of original subblocks and the plurality of generated inverted subblocks together.
According to the present invention, the information blocks are converted into the code blocks by dividing the information blocks which are extracted sequentially from an information sequence and acts as a conversion unit into a plurality of original subblocks, generating a plurality of inverted subblocks containing inverted information, which are obtained by inverting all original information being allocated to one or more segments contained in original subblocks, while correlating the original subblocks with the inverted subblocks respectively, and converting the information blocks into the code blocks by combining the plurality of original subblocks and the plurality of generated inverted subblocks together. Therefore, the information blocks each serving as a conversion unit are converted into the code blocks in which the original information allocated to every segment contained in the information blocks and the inverted information are combined together such that the numbers of the original information in a block acting as a conversion unit and the inverted information are balanced. As a result, the information blocks can be converted into the code blocks via simple procedures while suppressing the direct current component.
In the preferred embodiment of the present invention, each of the inverted subblocks is inserted between any original subblocks of the plurality of original subblocks when the plu
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Jean-Pierre Peguy
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