Patent application number | Description | Published |
20090073830 | REPRODUCING APPARATUS AND REPRODUCTION METHOD - A reproducing apparatus includes the following elements. A reproducing head unit irradiates an optical disk with a laser beam to obtain a reproduced signal. An offset cancellation circuit cancels an offset element of the reproduced signal. An automatic gain control circuit adjusts the amplitude of the reproduced signal processed through the offset cancellation circuit. A band switching control unit detects a fingerprint period during which the reproduced signal is affected by a fingerprint on the surface of the optical disk and, for the fingerprint period, switches a frequency band in which the offset cancellation circuit and the automatic gain control circuit function to a higher frequency band than that associated with a non-fingerprint period. A decoding unit decodes the reproduced signal processed through the automatic gain control circuit to output binary data. A data reproduction processing unit performs reproduction processing on the binary data to obtain reproduced data. | 03-19-2009 |
20100002556 | REPRODUCTION SIGNAL EVALUATION METHOD, REPRODUCTION SIGNAL EVALUATION UNIT, AND OPTICAL DISK DEVICE ADOPTING THE SAME - A reproduction signal evaluation method for evaluating 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, includes: a pattern extraction step of extracting, from the binary signal, a specific state transition pattern which has the possibility of causing a bit error; a step of computing a differential metric based on the binary signal; an extraction step of extracting the differential metric which is not greater than a predetermined signal processing threshold; a step of determining 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 of determining a standard deviation which corresponds to an error rate predicted from the mean value; and an evaluation step of evaluating a quality of the reproduction signal using the standard deviation. | 01-07-2010 |
20100214895 | REPRODUCTION SIGNAL EVALUATION METHOD, REPRODUCTION SIGNAL EVALUATION UNIT, AND OPTICAL DISK DEVICE ADOPTING THE SAME - A reproduction signal evaluation unit has: a pattern detection section for extracting, from a binary signal, a specific state transition pattern which has a possibility of causing a bit error; a differential metric computing section for computing a differential metric based on the binary signal of the extracted state transition pattern; an error computing section for computing an error rate predicted based on an integration value that is integrated by an integration section, a count value that is counted by a pattern count section, an integration value that is integrated by another integration section, and a count value that is counted by another pattern count section, and a standard deviation computing section for computing a standard deviation based on the computed error rate. | 08-26-2010 |
20110026383 | REPRODUCED SIGNAL EVALUATION METHOD AND WRITE ADJUSTMENT METHOD - The present invention aims to provide a reproduced signal evaluation method and a write adjustment method for offering a Blu-ray disc having a large storage capacity with excellent media compatibility. An evaluation index L-SEAT is calculated through signed addition using a Euclidean distance difference calculated from at least one of target signals in which a focused edge is shifted to the right and left, and the quality of the reproduced signal is evaluated based on the evaluation index. Write condition adjustment using the index enables write adjustment not depending on SNR and achieving high adjustment accuracy. | 02-03-2011 |
20120082201 | DATA DETECTING DEVICE, REPRODUCING DEVICE, AND DATA DETECTING METHOD - A data detecting device includes a multi-input adaptive equalizer, a binarizing unit, and an equalization error calculating unit. The multi-input adaptive equalizer includes a plurality of adaptive equalizers and outputs a reproduction information signal from a target track and a reproduction information signal from a close track close to the target track as equalization signals by calculating outputs of the adaptive equalizers, the reproduction information signals being input to the adaptive equalizers, respectively as reproduction information signals. The binarizing unit obtains binarized data by performing a binarization process on the equalization signals. The equalization error calculating unit obtains an equalization error from an equalization target signal obtained from the binarization result of the binarizing unit and an equalization signal output from the multi-input adaptive equalizer, and supplies the equalization error as a tap coefficient control signal for equalization to the adaptive equalizers. | 04-05-2012 |
20120201112 | REPRODUCTION SIGNAL EVALUATION METHOD, REPRODUCTION SIGNAL EVALUATION UNIT, AND OPTICAL DISK DEVICE ADOPTING THE SAME - 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. | 08-09-2012 |
20140064050 | SKEW DETECTION METHOD AND OPTICAL DISC DEVICE - There is provided a skew detection method including supplying reproduction signals, which are respectively reproduced approximately simultaneously from at least two tracks including a first adjacent track and a second adjacent track located on both sides of a main track, to first and second filters, causing a combining unit to combine output signals of the first and second filters with a reproduction signal which is reproduced from the main track approximately simultaneously with the first adjacent track and the second adjacent track so as to cancel crosstalk, causing a coefficient control unit to obtain an error with a target value of the output signal of the combining unit and control coefficients of the first and second filters so as to reduce the error, and detecting a skew of an optical disc from values of coefficients of predetermined taps of the first and second filters. | 03-06-2014 |
20150143208 | SIGNAL QUALITY EVALUATION APPARATUS, SIGNAL QUALITY EVALUATION METHOD, AND REPRODUCING DEVICE - Provided is a signal quality evaluation apparatus, including an error pattern detection unit to which binarized data obtained by performing a PRML decoding process on a reproduced signal of bit information by partial response equalization and maximum likelihood decoding is input, the error pattern detection unit configured to detect at least one specific error pattern that is a bit pattern that is longer than a constraint length of the PRML decoding process, a metric difference calculation unit configured to calculate a metric difference of the at least one specific error pattern that has been detected by the error pattern detection unit, and an index value generation unit configured to generate an index value of a reproduced signal quality by using a distribution of the metric difference obtained by the metric difference calculation unit. | 05-21-2015 |