Abstract: A method of assembling a railcar bogie includes: a positioning step of locking a wheelbase fixing jig to a pair of axle box devices to position the pair of axle box devices such that a wheelbase between a pair of wheelsets supported by the respective axle box devices becomes a predetermined designed value, the pair of axle box devices being arranged away from each other in a car longitudinal direction, the wheelbase fixing jig extending in the car longitudinal direction; a plate spring arranging step of making the pair of axle box devices support a plate spring extending in the car longitudinal direction; and a bogie frame arranging step of making a longitudinal direction middle portion of the plate spring support a bogie frame and coupling the bogie frame to the pair of axle box devices.

Abstract: A method of assembling a railcar bogie includes: a positioning step of locking a wheelbase fixing jig to a pair of axle box devices to position the pair of axle box devices such that a wheelbase between a pair of wheelsets supported by the respective axle box devices becomes a predetermined designed value, the pair of axle box devices being arranged away from each other in a car longitudinal direction, the wheelbase fixing jig extending in the car longitudinal direction; a plate spring arranging step of making the pair of axle box devices support a plate spring extending in the car longitudinal direction; and a bogie frame arranging step of making a longitudinal direction middle portion of the plate spring support a bogie frame and coupling the bogie frame to the pair of axle box devices.

Abstract: An optical disc drive includes: a means (116, 117) for generating a synchronization signal from a wobble read signal having location information configured by a wobbled groove; a timing correction circuit (127) that generates a control signal having a time width TW after a predetermined time length from the synchronization signal; and a DC level correction means (126) for clamping the DC level of an information read signal for the time width of the control signal, to thereby correct the DC level. After an information read signal in a vicinity of a head of a recorded data field is subjected to the DC level correction by using the DC level correction means (126), the signal is reproduced by binarizing means disposed at the successive stage.

Abstract: Reproduced signals are equalized by the least square technique by using a predetermined number of data samples binarized by a Viterbi decoder. Even when data written on an optical disk is unknown, the data can be equalized in a stable manner and can be reproduced at a low error rate without instability factors such as divergence due to interference.

Abstract: Optical information recording and reproducing medium 10 has two recording layers of first and second recording layers 12 and 14, from a laser beam incident surface side. In each control area 21, recording layer management information containing at least information indicating recording states of a plurality of areas into which the inside of data recording area 22 of each recording layer is divided is recorded. When recording or reproducing is performed on the second recording layer 14, the recording layer management information is checked, and a laser beam output is changed based on a recording state of an area corresponding to the first recording layer 12.

Abstract: Optical information recording and reproducing medium 10 has two recording layers of first and second recording layers 12 and 14, from a laser beam incident surface side. In each control area 21, recording layer management information containing at least information indicating recording states of a plurality of areas into which the inside of data recording area 22 of each recording layer is divided is recorded. When recording or reproducing is performed on the second recording layer 14, the recording layer management information is checked, and a laser beam output is changed based on a recording state of an area corresponding to the first recording layer 12.

Abstract: In an optical disk system using a PRML identification system, a method for deriving an optimum recording wave in a short period of time is provided. Parameters of the recording wave are adjusted by using an evaluation value obtained by a signal evaluation method which is suitable for the PRML identification system as an index. In this case, as a parameter adjusting method, a plurality of adjusting methods are utilized.

Abstract: Reproduction signals include patterns for which recognition errors are likely. With respect to such patterns, probable error patterns are prepared. Tables showing correct patterns and error patterns are prepared, and evaluation values accurately representing signal quality are calculated. In an apparatus using a PRML method, discrimination data and a plurality of predetermined bit sequence pairs are examined to detect matching. A bit sequence and corresponding two ideal responses are calculated. Euclidean distances between the two ideal responses and equalization signals are obtained, and the difference between the Euclidean distances is further obtained. A quality evaluation value of a reproduction signal is calculated based on a mean value, a standard deviation, an appearance probability of the predetermined bit sequence, and a Hamming distance between the predetermined bit sequence pairs.

Abstract: An optical disc including one or more than one recording layers has land areas (131) and groove areas (132) as recording tracks, wherein a data recording area of at least one of the recording layers is divided into a plurality of zones in a radial direction. In each of the divided zones, one or more than one prepits (133) with predetermined data are disposed in a track so that each header area is disposed at ever other boundary among the boundaries between the land areas and the groove areas. Each header area is shifted in the circumferential direction from other header areas apart from the each header area by two boundaries without overlapping in the radial direction.

Abstract: In order to stably carry out reproduction of information in an optical disc medium (10) using a PRML (partial-response maximum-likelihood) method for reproducing the signal, the optical disc medium (10) has not only a data recording area (14) where data is recorded at high density but also a system information recording area (16) where information is recorded at low density and binary equalizing/reproducing can be easily made. Information required to circuit setting is recorded in the system information recording area.

Abstract: A test pattern including a first test mark which is one unit-record-length longer than a shortest mark among modulating codes and a second test mark which is two or more unit-record-lengths longer than the shortest mark is recorded under a plurality of recording conditions (step S2). The recorded test pattern is reproduced (step S3), and based on a plurality of reproduced signals thus obtained, recording conditions allowing the first test mark and the second test mark, respectively, to be suitably recorded are selected (step S4). A recording condition for the shortest mark is determined by inference based on the recording conditions of the first test mark and the second test mark.

Abstract: In an operation method of an optical disc apparatus in which an optical disc is loaded, an optical disc is loaded in the optical disc apparatus; and the optical disc apparatus is evaluated based on a performance evaluation index for the loaded optical disc. The evaluation is achieved by acquiring an identification data used to identify a kind of the loaded optical disc; by selecting one of methods of calculating a performance evaluation index based on the identification data; by determining the performance evaluation index by using the selected method; and by evaluating an RF (radio frequency) signal obtained from the loaded optical disc based on the performance evaluation index.

Abstract: A recording data string is composed of a plurality of synchronous frames each of which has synchronous data and coding data. Data items in the coding data contributed to creation of the same column of the error correction code are arranged at regular intervals of E in the recording data string. A data segment length L is obtained by adding an additional synchronous frame to the recording data string. Wherein, a physical segment length A satisfies the equation L=mA, m is a natural number. And A is set indivisible by E.

Abstract: In order to evaluate the quality of a signal recorded on an optical recording medium, a target signal is obtained based on a predetermined data string and a predetermined partial response characteristic, and for each clock cycle, an equalization error is calculated that is a difference between the target signal and a signal reproduced each clock cycle. Further, the product of the equalization errors calculated at different times is obtained, and based on the obtained product, the quality of a signal is evaluated.

Abstract: In an optical disk system using a PRML identification system, a method for deriving an optimum recording wave in a short period of time is provided. Parameters of the recording wave are adjusted by using an evaluation value obtained by a signal evaluation method which is suitable for the PRML identification system as an index. In this case, as a parameter adjusting method, a plurality of adjusting methods are utilized.

Abstract: Optical information recording and reproducing medium 10 has two recording layers of first and second recording layers 12 and 14, from a laser beam incident surface side. In each control area 21, recording layer management information containing at least information indicating recording states of a plurality of areas into which the inside of data recording area 22 of each recording layer is divided is recorded. When recording or reproducing is performed on the second recording layer 14, the recording layer management information is checked, and a laser beam output is changed based on a recording state of an area corresponding to the first recording layer 12.

Abstract: A test pattern including a first test mark which is one unit-record-length longer than a shortest mark among modulating codes and a second test mark which is two or more unit-record-lengths longer than the shortest mark is recorded under a plurality of recording conditions (step S2). The recorded test pattern is reproduced (step S3), and based on a plurality of reproduced signals thus obtained, recording conditions allowing the first test mark and the second test mark, respectively, to be suitably recorded are selected (step S4). A recording condition for the shortest mark is determined by inference based on the recording conditions of the first test mark and the second test mark.

Abstract: An optical disc including one or more than one recording layers has land areas (131) and groove areas (132) as recording tracks, wherein a data recording area of at least one of the recording layers is divided into a plurality of zones in a radial direction. In each of the divided zones, one or more than one prepits (133) with predetermined data are disposed in a track so that each header area is disposed at ever other boundary among the boundaries between the land areas and the groove areas. Each header area is shifted in the circumferential direction from other header areas apart from the each header area by two boundaries without overlapping in the radial direction.

Abstract: In a code modulating method and a code modulating apparatus, a run length has an encoding rate of ? which is equal to that of (1, 7) modulation, and indicates the number of “0” bits between adjacent ones of “1” bits in the channel bit train. A data bit train is converted into the channel bit train so that the run length has a minimum value 1 and a maximum value 10. Further, upon converting any data bit train, the channel bit train does not include a pattern “1010101010101” in which the run length 1 is continuously repeated six times or more. The channel bit train has a DSV (Digital Sum Value) control bit which selects the “0” bit or “1” bit in accordance with a DSV. The channel bit train obtained by using random data for the data bit train is NRZI converted into a signal. A frequency component of the signal is reduced from a maximum value of the frequency component by 20 dB or less as a power density at a frequency of {fraction (1/10,000)} or less of a channel clock frequency.

Abstract: In order to stably carry out reproduction of information in an optical disc medium (10) using a PRML (partial-response maximum-likelihood) method for reproducing the signal, the optical disc medium (10) has not only a data recording area (14) where data is recorded at high density but also a system information recording area (16) where information is recorded at low density and binary equalizing/reproducing can be easily made. Information required to circuit setting is recorded in the system information recording area.