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: An optical disc medium includes a land and a groove at which information can be recorded. A predetermined number of address information units which record address information of the land or groove are provided in a circumferential direction of the optical disc medium. The address information unit of the land includes three or more address recording areas capable of recording address information. The address information is recorded on one area selected from among the three or more address recording areas. The address information unit of the land has address information which is recorded, in the same modulation, on the side of the inner adjacent groove and on the side of the outer adjacent groove. The one area to be selected from among the three or more address recording areas for recording the address information of the land is different among three address information units adjacently arranged in a radial direction.

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 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: A discrete Fourier transform circuit (201) calculates a first frequency spectrum in a predetermined frequency range from a detection signal in a predetermined segment. An expectation calculation circuit (202) calculates a second frequency spectrum corresponding to an expectation signal of a pattern of digital information that is present in the predetermined segment and obtained via an optical disc (100). A branch metric calculation circuit (203) calculates a difference between the first frequency spectrum and the second frequency spectrum. A maximum likelihood decoding circuit (207) decodes the digital information by selecting a pattern in which the difference between the first frequency spectrum and the second frequency spectrum is minimized as a decoding result.

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: A discrete Fourier transform circuit (201) calculates a first frequency spectrum in a predetermined frequency range from a detection signal in a predetermined segment. An expectation calculation circuit (202) calculates a second frequency spectrum corresponding to an expectation signal of a pattern of digital information that is present in the predetermined segment and obtained via an optical disc (100). A branch metric calculation circuit (203) calculates a difference between the first frequency spectrum and the second frequency spectrum. A maximum likelihood decoding circuit (207) decodes the digital information by selecting a pattern in which the difference between the first frequency spectrum and the second frequency spectrum is minimized as a decoding result.

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 element comprising a vacuum-sintered body comprising a plurality of particles each having a two-layer structure comprising a ceramic particle and a coating layer, wherein the ceramic particle comprises LnxAlyO[x+y]×1.5, where Ln represents a rare-earth element, x represents 1?x?10, and y represents 1?y?5, and has an average particle diameter of 1 ?m or more and 10 ?m or less, and wherein the coating layer comprises a ceramic having a lower sintering temperature than a sintering temperature of the ceramic particle.

Abstract: An information recording medium according to the present invention includes an information recording layer on which information is recordable, and is evaluated using an evaluation index which is found based on a ratio of a center of an amplitude of a reproduction signal corresponding to a second shortest mark and a second shortest space, with respect to a center of an amplitude of a reproduction signal corresponding to a longest mark and a longest space.

Abstract: A method for rating an information recording medium according to the present invention includes the steps of: receiving a digital read signal, which has been generated based on an analog read signal representing information that has been read from the information recording medium, and shaping the waveform of the digital read signal; subjecting the shaped digital read signal to maximum likelihood decoding, thereby generating a binarized signal showing a result of the maximum likelihood decoding; and calculating the quality of the digital read signal based on the shaped digital read signal and the binarized signal. If the quality of the read signal is calculated by a PRML method in which a number of zero-cross portions are included in a merging path of a minimum difference metric, the quality is calculated by using only a state transition pattern in which only one zero-cross portion is included in a merging path of a non-minimum difference metric.

Abstract: According to the present invention, when an apparatus performs reproduction from an optical disc of a format not compatible to the apparatus, the apparatus is prevented from obtaining an incorrect address and thus causing a malfunction. A recording method according to the present invention performs first conversion of bit-inverting m number (1?m<n; m an integer) of symbols at prescribed positions of a code word coded using an error correction code by a Reed-Solomon code and including symbol C(i) [i=0, 1, 2, . . . n; n is an integer] to generate conversion information; and records the conversion information on a first recording medium.

Abstract: An optical element is formed by vacuum-sintering a molded body of ceramic particles having an average particle diameter of 1 ?m or more and 10 ?m or less and including LnxAlyO[x+y]×1.5 (Ln represents a rare-earth element, 1?x?10, and 1?y?5). Ln preferably includes at least one kind selected from La, Gd, Yb, and Lu. The optical element preferably has a refractive index of 1.85 or more and 2.06 or less, and an Abbe number of 48 or more and 65 or less. The obtained optical element has optical properties of high refractive index and low dispersibility.

Abstract: An optical element is formed by vacuum-sintering a molded body of ceramic particles having an average particle diameter of 1 ?m or more and 10 ?m or less and including LnxAlyO[x+y]×1.5 (Ln represents a rare-earth element, 1?x?10, and 1?y?5). Ln preferably includes at least one kind selected from La, Gd, Yb, and Lu. The optical element preferably has a refractive index of 1.85 or more and 2.06 ?m or less, and an Abbe number of 48 or more and 65 or less. The obtained optical element has optical properties of high refractive index and low dispersibility.

Abstract: A waveform shaping portion receives a digital reproduced signal generated from an analog reproduced signal reproduced from an information recording medium and shapes the waveform of the digital reproduced signal. A maximum likelihood decoding portion applies maximum likelihood decoding to the digital reproduced signal in the shaped waveform and generates a binarized signal indicating the result of the maximum likelihood decoding. A phase detection portion extracts, during the maximum likelihood decoding, a phase error using state transition patterns having only a single zero cross point among differential metrics at a plurality of merging points at which a set of paths branched from a given state merges. A synchronization detection portion generates a reproduction clock signal using the phase error that has been detected and brings the digital reproduced signal into synchronization with the reproduction clock signal that has been generated.

Abstract: A signal evaluation method according to the present invention is a method for evaluating a read signal, retrieved from an information recording medium, based on a binarized signal generated from the read signal by a PRML method.

Abstract: A bit pattern for a run-in area which allows data reproduction to be performed stably even when the recording density of an optical disc is increased is provided. An optical disc according to the present invention includes tracks, each of which divided into a plurality of recording blocks. Each of the plurality of blocks includes a run-in area and a data area. In the run-in area, a prescribed run-in bit pattern is recordable; and in the data area, bit patterns having a plurality of bit lengths obtained by modulating data as a recording target in accordance with a prescribed modulation rule are recordable. In this optical disc, at least one of spatial frequencies corresponding to the bit patterns having the plurality of bit lengths is higher than a cutoff frequency. The run-in bit pattern recordable in the run-in area includes the bit patterns having the plurality of bit lengths, from which the bit pattern corresponding to the frequency higher than the OTF cutoff frequency has been excluded.