Dynamic information storage or retrieval – Binary pulse train information signal – Binary signal processing for controlling recording light...
Reexamination Certificate
2000-06-06
2002-04-09
Huber, Paul W. (Department: 2651)
Dynamic information storage or retrieval
Binary pulse train information signal
Binary signal processing for controlling recording light...
C369S059220, C369S124020
Reexamination Certificate
active
06370097
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an information recording and reproducing method, an information recording and reproducing system, an information recording apparatus, and an information reproducing apparatus, and more particularly relates to an information recording and reproducing method, an information recording and reproducing system, an information recording apparatus and an information reproducing apparatus, which can record and reproduce digital data onto and from an information recording medium.
2. Description of the Related Art
There is a research with regard to a technique for recording or reproducing multi-level digital data having a plurality of values other than “0” or “1” onto or from an information recording medium in order to record or reproduce a large amount of digital data onto or from an optical disc as the information recording medium, at a high density.
Here, as a conventional technique in this field, there is a recording and reproducing method, which is a combination of (i) a pit edge multi-level recording method for changing the edge positions of a pit formed on the optical disc (namely, the positions of two edges of the pit in a rotational direction of the optical disc), by several steps in the rotational direction depending upon a value of digital data to be recorded to thereby record the digital data, and (ii) an RPR (Radial direction Partial Response) reproducing method for reproducing the recorded digital data by simultaneously reading the edges of pits on two tracks adjacent to each other. Such a recording and reproducing method is disclosed in detail in, for example, Japanese Patent Application Laid Open publication NO. Hei 10-74322.
Next, the above-mentioned information recording and reproducing method is schematically explained below with reference to
FIG. 10
to FIG.
12
C.
FIG. 10
is a block diagram showing the schematic configuration of an information recording and reproducing system used in the information recording and reproducing method.
FIG. 11
is an enlarged plan view showing an aspect of the pit on the optical disc.
FIG. 12A
to
FIG. 12C
are timing charts describing the information recording and reproducing method.
As shown in
FIG. 10
, a conventional information recording and reproducing system S′ is provided with a recording system R′ for digitally recording information data Sin onto an optical disc
1
and a reproducing system P′ for reproducing the recorded information data Sin from the optical disc
1
to thereby generate reproduction data Sout.
Next, the detailed configuration and operation of the recording system R′ is explained below.
As shown in
FIG. 10
, the recording system R′ is provided with a Reed Solomon encoding unit
100
, a mapping unit
101
, a pre-coding unit
102
, a pit edge modulating unit
103
and a recording head
104
.
Next, the operations of the respective units are explained below.
The Reed Solomon encoding unit
100
performs an encoding process including an addition of a Reed Solomon error correction code onto the information data Sin, and generates an information code Se, and then outputs it to the mapping unit
101
.
Accordingly, the mapping unit
101
converts the information code Se corresponding to a plurality of bits among the inputted information code Se, into a multi-level symbol Sts, and outputs it to the pre-coding unit
102
. Actually, for example, the information code Se corresponding to three bits is converted into two of the multi-level symbols Sts having three levels of “0”, “1” and “2”.
Next, the pre-coding unit
102
performs a pre-coding operation onto the generated multi-level symbol Sts, and converts the multi-level symbol Sts into a record symbol Srs similarly having the three levels of “0”, “1” and “2”, and then outputs it to the pit edge modulating unit
103
.
Then, the pit edge modulating unit
103
generates a record pulse Srp, whose edge positions (namely, a rising up position and a falling down position of the pulse) are changed by three steps in accordance with respective values in the generated record symbols Srs, and then outputs it to the recording head
104
.
Accordingly, the recording head
104
irradiates a record laser light, whose intensity is modulated in accordance with the record pulse Srp, onto a track (not shown) of the optical disc
1
, and forms on the track a pit row composed of pits having edges (implying two edges existing in a rotational direction of the optical disc
1
, and hereafter, implying the same) at positions corresponding to the generated record pulse Srp.
The above-mentioned operations of the recording system R′ enables the original information data Sin to be recorded on the optical disc
1
, by using the pits in which the edge position is changed by the three steps.
The detailed configuration and operation of the reproducing system P′ is explained below.
As shown in
FIG. 10
, the reproducing system P′ is provided with a reproducing head
105
, a waveform equalizer
106
, a level judging unit
107
, a remainder calculating unit
108
, a reverse mapping unit
109
and a Reed Solomon decoding unit
110
.
The operations of the respective units are explained below.
The reproducing head
105
irradiates a reproduction laser light having a constant intensity onto the optical disc
1
, reads the formed pit row, generates an analog reproduction signal Spa having a level corresponding to the edge position of the pit, and outputs it to the waveform equalizer
106
.
A beam spot formed on the optical disc
1
by the reproduction laser light is moved on a central line between two tracks adjacent to each other, and two pit edges on the two tracks adjacent to each other are read at the same time. Thus, a level of the generated analog reproduction signal Spa corresponds to an added value of the two record symbols Srs recorded on the two tracks adjacent to each other. In a case of the above-mentioned record symbol Srs having the three levels of “0”, “1” and “2”, the reproduction analog signal Spa takes five levels composed of “0” (if the values of the two record symbols Srs adjacent to each other are both “0”), “1” (if the values of the two record symbols Srs are “0” and “1”), “2” (if the values of the two record symbols Srs are “0” and “2”, or both “1”), “3” (if the values of the two record symbols Srs are “1” and “2”), or “4” (if the values of the two record symbols Srs are both “2”).
Next, the waveform equalizer
106
filters the generated reproduction analog signal Spa by using a filter having a frequency characteristic of a high frequency band emphasis type, and re-shapes its waveform, to thereby generate a re-shaped analog reproduction signal Sep. Then, the waveform equalizer
106
outputs it to the level judging unit
107
.
Accordingly, the level judging unit
107
samples the re-shaped analog reproduction signal Sep by using a preset sampling clock, and compares its voltage level with four threshold levels, and then generates a judgment symbol Sjs of five levels corresponding to the reproduction analog signal Spa of the five levels, and further outputs it to the remainder calculating unit
108
.
Next, the remainder calculating unit
108
calculates the respective remainders when the respective values (“0”, “1”, “2”, “3” and “4”) of the generated judgment symbol Sjs are divided by 3, and generates a reproduction symbol Sps having three levels of “0”, “1” and “2”, and then outputs it to the reverse mapping unit
109
.
Then, the reverse mapping unit
109
carries out a converting process inverse to that of the mapping unit
101
, and converts the two reproduction symbols Sps into a reproduction information code Spe of three bits, and then outputs it to the Reed Solomon decoding unit
110
.
Finally, the Reed Solomon decoding unit
110
performs a demodulating process using the Reed Solomon error correction code onto the reproduction information code Spe, and generates the final reproduction data Sout, and then outputs it to the external portion.
In t
Goto Toshio
Hayashi Hideki
Huber Paul W.
Morgan & Lewis & Bockius, LLP
Pioneer Corporation
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