Abstract: A decoding device (1) has: a reliability calculating unit (5) which calculates reliability information having a non-linear relationship with a noise distribution of a PR communication path (3) in at least part of or all of the reliability information based on characteristics of the PR communication path (3) and a predetermined modulation rule from an encoded signal that is obtained from the PR communication path (3); a reliability correcting unit (17) which corrects the reliability information calculated by a reliability calculating unit (5); and an error correction decoding unit (18) which performs error correction decoding on the reliability information corrected by the reliability correcting unit (17).

Abstract: A phase difference error detecting unit detects a phase difference error component included in a phase difference component; a phase difference correcting unit corrects a first signal having the phase difference component as an angle of a cosine function and a second signal whose angle of the cosine function differs from that of the first signal by approximately ?/2 based on the detected phase difference error component; a phase operating unit operates a phase difference component from the first signal and the second signal corrected by the phase difference correcting unit; and the phase difference correcting unit obtains the corrected first signal and the corrected second signal by rotating a coordinate point represented by the first signal and the second signal on a polar coordinate plane by an angle corresponding to the phase difference error component.

Abstract: When bnt denotes the length adjustment amount of a front edge portion of an nT recording mark (n: integer, T: channel clock length) and cnT denotes the length adjustment amount of a rear edge portion thereof with respect to a channel clock reference, d denotes a minimum value of n and k denotes a maximum value of n, the length adjustment amount bdT of a front edge portion of a shortest recording mark dT, the length adjustment amount cdT of a rear edge portion of the shortest recording mark dT, the length adjustment amount bkT of a front edge portion of a longest recording mark kT and the length adjustment amount ckT of a rear edge portion of the longest recording mark dT satisfy bdT+cdT>bkT+ckT.

Abstract: An information reproducing apparatus includes a photodetector (200A) divided by a dividing line parallel to a recording track scanning direction into a first light-receiving section (202, 203) that receives reflected light of a center section of a recording track and a second light-receiving section (201, 204) that receives reflected light of a portion adjacent, in a radial direction of an optical disc, with respect to the center section, a first adaptive equalization filter (107) that performs waveform equalization of an output signal from the first light-receiving section (202, 203), a second adaptive equalization filter (120) that performs waveform equalization of an output signal from the second light-receiving section (201, 204), and a data decoder (108) that decodes reproduction data based on an output waveform from the first adaptive equalization filter (107) and an output waveform from the second adaptive equalization filter (120).

Abstract: An information reproducing apparatus includes a photodetector (200A) divided by a dividing line parallel to a recording track scanning direction into a first light-receiving section (202, 203) that receives reflected light of a center section of a recording track and a second light-receiving section (201, 204) that receives reflected light of a portion adjacent, in a radial direction of an optical disc, with respect to the center section, a first adaptive equalization filter (107) that performs waveform equalization of an output signal from the first light-receiving section (202, 203), a second adaptive equalization filter (120) that performs waveform equalization of an output signal from the second light-receiving section (201, 204), and a data decoder (108) that decodes reproduction data based on an output waveform from the first adaptive equalization filter (107) and an output waveform from the second adaptive equalization filter (120).

Abstract: A decoding device includes: an interference canceling circuit (104) which extracts, from states of 2K-number (where K is a natural number) of detected signals that are likely within a range of K bit width where an interference between bits of the digital information occurs due to predetermined frequency characteristics, most likely 2M-number (where M is a natural number) of detected signals respectively corresponding to states of 2M-number of detected signals which exist within a range of M bit width that is included in the range of K bit width; and a Viterbi decoding circuit (105) which generates a decoded signal by calculating differences between the 2M-number of detected signals extracted by the interference canceling circuit (104) and expectation signals respectively corresponding to the 2M-number of detected signals and also by selecting a transition sequence of a state of a detected signal for which the calculated difference is smallest.

Abstract: The laser light source, the PBS, and the reference light mirror are arranged in such a manner as to simultaneously satisfy Lsig+LBS?s (Lld/m) (s: positive integer, m: positive integer), Lref+LBS?t (Lld/m) (t: positive integer), and u(Lld/m)?(?L/2)?Lsig?Lref?u(Lld/m)+(?L/2) (u: integer), where Lld represents an in-vacuum internal resonator length of the laser light source, LBS represents an in-vacuum-converted optical path length of a laser beam between the emission end surface of the laser light source and the PBS, Lsig represents an in-vacuum-converted optical path length of signal light between the PBS and the reflecting unit of the optical disk, Lref represents an in-vacuum-converted optical path length of reference light between the PBS and the reference light mirror, and ?L represents an interference permissible optical path length of the laser beam.

Abstract: The present invention is to realize a proper inner zone layout in a quadruple-layer disk. A test area is provided in the inner zone (inner circumference side area) in each of recording layers. If two test areas closer to the outer circumference, of four test areas, are defined as a first pair and two test areas closer to the inner circumference are defined as a second pair, the test areas of the first pair and the test areas of the second pair are so disposed as to be prevented from overlapping with each other in the layer direction. Two test areas of the first pair have the same consumption direction of the test area, and are so disposed that the areas to be used next hardly overlap with each other in the layer direction. Two test areas of the second pair have the same consumption direction of the test area opposite to the consumption direction of the test area in the first pair, and are so disposed that the areas to be used next hardly overlap with each other in the layer direction.

Abstract: Disclosed is an information recording medium (1) having a plurality of pits (301) which are formed periodically, wherein information is recorded by irradiating a laser beam onto a pit string constituted by the plurality of pits (301) and changing the shape of the pits (301), the pit string is periodically wobbled, a length of a period (fp) of the pits (301) is a diffraction limit of the laser beam or less, and the period of the pit string is n times (n is a positive integer) of the period of the pits.

Abstract: An integral multiple of a period of wobbling in a portion other than address information of groove tracks (105, 107) is consistent with a length of one circumference of each of the groove tracks (105, 107), an integral multiple of a period of the address information is consistent with the length of one circumference of each of the groove tracks (105, 107), and pieces of information that differ between adjacent groove tracks (105, 107) among the address information is recorded by a predetermined wobble pattern which at least differs between the adjacent groove tracks (105, 107).

Abstract: A decoding system includes: a modulator which modulates user data by using a modulation rule which converts the user data into a modulation pattern; a regenerator which generates a regenerative signal from a signal obtained by transmitting the user data after modulation through a transmission path; a transmission path decoder which generates signals as generation signals corresponding to the modulation pattern, and calculates k (k is a positive integer) distances between the regenerative signal and the k generation signals in an interval having a length fixedly or dynamically determined; and a demodulator which calculates reliability information for each bit of the user data, and estimates each bit of the user data based on the calculated reliability information. The demodulator calculates likelihood that each bit of the user data is 1 and each bit of the user data is 0 by Formula (A), and calculates the reliability information by Formula (B).

Abstract: The laser light source, the PBS, and the reference light mirror are arranged in such a manner as to simultaneously satisfy Lsig+LBS?s (Lld/m) (s: positive integer, m: positive integer), Lref+LBS?t (Lld/m) (t: positive integer), and u(Lld/m)?(?L/2)?Lsig?Lref?u(Lld/m)+(?L/2) (u: integer), where Lld represents an in-vacuum internal resonator length of the laser light source, LBS represents an in-vacuum-converted optical path length of a laser beam between the emission end surface of the laser light source and the PBS, Lsig represents an in-vacuum-converted optical path length of signal light between the PBS, Lsig and the reflecting unit of the optical disk, Lref represents an in-vacuum-converted optical path length of reference light between the PBS and the reference light mirror, and ?L represents an interference permissible optical path length of the laser beam.

Abstract: A decoding device (1) has: a reliability calculating unit (5) which calculates reliability information having a non-linear relationship with a noise distribution of a PR communication path (3) in at least part of or all of the reliability information based on characteristics of the PR communication path (3) and a predetermined modulation rule from an encoded signal that is obtained from the PR communication path (3); a reliability correcting unit (17) which corrects the reliability information calculated by a reliability calculating unit (5); and an error correction decoding unit (18) which performs error correction decoding on the reliability information corrected by the reliability correcting unit (17).

Abstract: An optical head 12 reproduces information recorded on an optical disc 11, a BCA detector 21 and a medium discriminating circuit 22 acquire waveform distortion information for specifying a waveform distortion of a reproduction signal reproduced by the optical head 12, and a variable waveform equalizer 16 changes a parameter used in a distortion reduction processing for reducing the waveform distortion of the reproduction signal based on the waveform distortion information.

Abstract: A phase difference error detecting unit detects a phase difference error component included in a phase difference component; a phase difference correcting unit corrects a first signal having the phase difference component as an angle of a cosine function and a second signal whose angle of the cosine function differs from that of the first signal by approximately ?/2 based on the detected phase difference error component; a phase operating unit operates a phase difference component from the first signal and the second signal corrected by the phase difference correcting unit; and the phase difference correcting unit obtains the corrected first signal and the corrected second signal by rotating a coordinate point represented by the first signal and the second signal on a polar coordinate plane by an angle corresponding to the phase difference error component.

Abstract: Shape-wise thicknesses of a cover layer and first through (N?1)th intermediate layers of an optical recording medium having refractive indexes nr1, nr2 are converted into thicknesses t1, t2 of the respective layers having a predetermined refractive index which makes a divergent amount equal to a divergent amount of a light beam resulting from the thicknesses tr1, tr2, a difference DFF between the sum of a thickness “ti” through a thickness “tj”, and the sum of a thickness “tk” through a thickness “tm” is set to 1 ?m or more (where i, j, k, and m are each any positive integer satisfying i?j<k?m?N), and the thicknesses t1, t2 are calculated by products of a function f(n) expressed by the following formula (1), and the thicknesses tr1, tr2: f(n)=?1.088n3+6.1027n2?12.042n+9.1007??(1) in the formula (1), n=nr1, nr2, . . . , and nrN.

Abstract: A reproduction signal evaluation method evaluates the quality of a reproduction signal reproduced from an information recording medium based on a binary signal generated from the reproduction signal using a PRML signal processing system. A pattern extraction step extracts, from the binary signal, a specific state transition pattern which has the possibility of causing a bit error; a step computes a differential metric based on the binary signal; an extraction step extracts the differential metric which is not greater than a predetermined signal processing threshold; a step determines a mean value of the differential metrics which are not greater than the signal processing threshold and extracted in the extraction step; a standard deviation computing step determines a standard deviation which corresponds to an error rate predicted from the mean value; and an evaluation step evaluates a quality of the reproduction signal using the standard deviation.

Abstract: A recording medium and apparatus enable the number of data units of recording pulse information to be reduced. The recording medium includes an information area for recording set values of a recording pulse for forming recording marks. The set values include preceding space-based set values having a first reference value as a set value of a recording pulse corresponding to a predetermined preceding space and a first difference set value of a recording pulse corresponding to a space other than the predetermined preceding space; and trailing space-based set values having a second reference value as a set value of a recording pulse corresponding to a predetermined trailing space and a second difference set value of a recording pulse corresponding to a space other than the predetermined trailing space and which is expressed as a difference from the second reference value.

Abstract: The present invention is to realize a proper inner zone layout in a quadruple-layer disk. A test area is provided in the inner zone (inner circumference side area) in each of recording layers. If two test areas closer to the outer circumference, of four test areas, are defined as a first pair and two test areas closer to the inner circumference are defined as a second pair, the test areas of the first pair and the test areas of the second pair are so disposed as to be prevented from overlapping with each other in the layer direction. Two test areas of the first pair have the same consumption direction of the test area, and are so disposed that the areas to be used next hardly overlap with each other in the layer direction. Two test areas of the second pair have the same consumption direction of the test area opposite to the consumption direction of the test area in the first pair, and are so disposed that the areas to be used next hardly overlap with each other in the layer direction.

Abstract: When ld0 denotes an initial optical path length that is a length of an optical path, along which the signal light travels, as converted using a refractive index in vacuum, lm0 denotes an initial optical path length that is a length of an optical path, along which the reference light travels, as converted using a refractive index in vacuum, ?l denotes a fluctuation width of a difference in optical path lengths between the signal light and the reference light as converted using a refractive index in vacuum, ?0 denotes a central oscillation wavelength of the wavelength-variable laser, and ?? denotes an oscillation wavelength variable range of the wavelength-variable laser, then an initial optical path difference |ld0?lm0| satisfies |ld0?lm0|>(?l/??)?0.