Abstract: A magnetic disk drive having an active filter supplied with a read waveform of a magnetic disk, an A/D converter supplied with an output of the active filter, a waveform equalizer supplied with an output of the A/D converter. An adaptive learning unit for adaptively learning a boost characteristic of the active filter on the basis of an input and an output of the waveform equalizer so that error in the waveform equalizer is minimized. An abnormal learning detection unit for detecting an abnormal operation in adaptive learning of the boost characteristic just after learning of a sector and a boost characteristic resetter for resetting the boost characteristic before adaptive learning to an initial value before adaptive learning of a next sector when abnormality occurs in adaptive learning of the adaptive learning unit.

Abstract: A servo control method for a storage media includes arranging a plurality of servo sectors along a circumferential direction of the disk-type storage medium without successively arranging the plurality of servo sectors in a radial direction and arranging a plurality of data sectors which are not split by the servo sectors.

Abstract: A signal processing circuit for a magnetic recording/reproducing apparatus, including at least an AGC, a PLL, a LPF, an equalizer circuit and a detection circuit, wherein a coefficient compensation circuit is formed by defining a constitution of the equalizer circuit, an error detection circuit is provided which operates by receiving input from the detection circuit, and the LSI is formed by a plurality of analog and digital chips, and the analog and digital chips are connected by current-output type D/A converters connected to at least the AGC and the PLL.

Abstract: For the purpose of providing technique by which even when large skew of a disk or a head occurs due to a thermal shock, an outside shock, or the like, a servo signal area is not extended, and a performance loss caused by head change is not produced, a servo detection control system according to the present invention comprises: a learning means by head change including a servo sector interval measuring unit for measuring an interval of servo signal areas, which may occur at the time of head change among a plurality of heads; a time difference calculating unit for calculating head-change time difference from a value measured by the servo sector interval measuring unit; and a time difference storage unit for storing a result of calculation made by the time difference calculating unit; and a compensation and control means for compensating start timing of servo detection after head change using a stored value of the time difference storage unit.

Abstract: A servo control method for a storage media includes arranging a plurality of servo sectors along a circumferential direction of the disk-type storage medium without successively arranging the plurality of servo sectors in a radial direction and arranging a plurality of data sectors which are not split by the servo sectors.

Abstract: A magnetic recording and reproduction apparatus, includes a circuit for changing a reference amplitude value of a Viterbi detector. The circuit is used to record and reproduce data with the reference amplitude value displaced from a reference value, thereby measuring the data error rate. Displacement of the reference amplitude from a reference value increases the data error rate, and therefore the data error rate can be measured within a short time. A data error rate with the reference amplitude equal to a reference value is estimated from the data error rate measurement, thereby making it possible to evaluate the degree of accuracy of a magnetic recording and reproduction apparatus. The data error rate is measured with the reference amplitude of the Viterbi detector displaced from a reference value while changing the equalization coefficient value of a waveform equalizer, the cut-off frequency of a low-pass filter and the write precompensation amount of a write precompensation circuit.

Abstract: There is provided a magnetic disk drive in which the adaptability of read signal processing of the magnetic disk drive is enhanced so that the frequency of retry or miscorrection in use is reduced. This magnetic disk drive has a read circuit, and a channel condition measuring circuit. An output of an A/D converter contained in the read circuit is supplied to a digital equalizing circuit so as to be equalized accurately. Upon input of a signal for instructing a coefficient learning circuit to learn the coefficient of the digital equalizing circuit, the initial coefficient registered in a register is set as a coefficient value in another register and the coefficient learning circuit is operated to start consecutive learning of coefficient values. In the channel condition measuring circuit, errors in a row of output values of the digital equalizing circuit are calculated and an integrated value of squares of the errors is compared with an error threshold value.

Abstract: There is provided a magnetic disk drive in which the adaptability of read signal processing of the magnetic disk drive is enhanced so that the frequency of retry or miscorrection in use is reduced. This magnetic disk drive has a read circuit, and a channel condition measuring circuit. An output of an A/D converter contained in the read circuit is supplied to a digital equalizing circuit so as to be equalized accurately. Upon input of a signal for instructing a coefficient learning circuit to learn the coefficient of the digital equalizing circuit, the initial coefficient registered in a register is set as a coefficient value in another register and the coefficient learning circuit is operated to start consecutive learning of coefficient values. In the channel condition measuring circuit, errors in a row of output values of the digital equalizing circuit are calculated and an integrated value of squares of the errors is compared with an error threshold value.

Abstract: A magnetic disk including a plurality of servo sectors and data sectors along a circumference thereof includes full-format servo sectors which are successively arranged in a radial direction of the disk and which include track information and short-format servo sectors which are arranged between the full-format servo sectors not to be successive in a radial direction of the disk and which include position error signals. The short-format servo sectors do not split the data sectors.

Abstract: The present invention enables recovery of data reading, even when TA or defective medium that will make it impossible to increase the number of retries or to read the data part occur in the AGC/PLL part.

Abstract: The equalizer is capable of generating an equalized output that is compensated in the non-linearity of the signal reproduced by an MR head and a reliable high-density magnetically recorded-signal reproducer. The equalizer of an FIR-type filter structure includes a plurality of delay elements for delaying an input signal by a certain period, a plurality of coefficient processing units provided to input or output taps of the delay elements, and an adder for obtaining the sum of the outputs of the coefficient processing units. The distortion of the reproduced waveform can be corrected by a relatively simple circuit structure by comparing the signal value inputted to the coefficient processing unit from each tap with a predetermined threshold level and changing the signal value and a coefficient value to be multiplied in accordance with the comparison result.

Abstract: An information recording/reproducing apparatus includes first and second data demodulators having different data discriminating capabilities. The first data demodulator has a lower data discriminating capability and the second data demodulator has a higher data discriminating capability. When the reliability of reliability information for demodulation data generated by the first data demodulator, the second data demodulator is operated so that demodulation data generated by the first data demodulator is replaced by demodulation data generated by the second data demodulator during a period of time when the reliability of the reliability information is deteriorated.

Abstract: A signal processing circuit for a magnetic recording/reproducing apparatus, including at least an AGC, a PLL, a LPF, an equalizer circuit and a detection circuit, wherein a coefficient compensation circuit is formed by defining a constitution of the equalizer circuit, an error detection circuit is provided which operates by receiving input from the detection circuit, and the LSI is formed by a plurality of analog and digital chips, and the analog and digital chips are connected by current-output type D/A converters connected to at least the AGC and the PLL.

Abstract: An information recording/reproducing apparatus includes first and second data demodulators having different data discriminating capabilities. The first data demodulator has a lower data discriminating capability and the second data demodulator has a higher data discriminating capability. When the reliability of reliability information for demodulation data generated by the first data demodulator, the second data demodulator is operated so that demodulation data generated by the first data demodulator is replaced by demodulation data generated by the second data demodulator during a period of time when the reliability of the reliability information is deteriorated.

Abstract: The present invention relates to a hair cuticle caring method or volume enhancing method, which comprises treating hair with a composition containing (A) a cationic surfactant and (B) an organic acid or salt thereof in a combination to give, when an aqueous solution containing 1 mM of each of the components is formed, 40 mN/m or less as the surface tension of the aqueous solution at 27±0.5° C. By the application of the above-described composition, the lift-up of the hair cuticle can be suppressed, the volume can be enhanced softly, moisturized but stickiness-free feeling is imparted and styling ease is improved.

Abstract: A magnetic recording and reproduction apparatus: includes a circuit for changing a reference amplitude value of a Viterbi detector. The circuit is used to record and reproduce data with the reference amplitude value displaced from a reference value, thereby measuring the data error rate. Displacement of the reference amplitude from a reference value increases the data error rate, and therefore the data error rate can be measured within a short time. A data error rate with the reference amplitude equal to a reference value is estimated from the data error rate measurement, thereby making it possible to evaluate the degree of accuracy of a magnetic recording and reproduction apparatus. The data error rate is measured with the reference amplitude of the Viterbi detector displaced from a reference value while changing the equalization coefficient value of a waveform equalizer, the cut-off frequency of a low-pass filter and the write precompensation amount of a write precompensation circuit.

Abstract: The equalizer is capable of generating an equalized output that is compensated in the non-linearity of the signal reproduced by an MR head and a reliable high-density magnetically recorded-signal reproducer. The equalizer of an FIR-type filter structure includes a plurality of delay elements for delaying an input signal by a certain period, a plurality of coefficient processing units provided to input or output taps of the delay elements, and an adder for obtaining the sum of the outputs of the coefficient processing units. The distortion of the reproduced waveform can be corrected by a relatively simple circuit structure by comparing the signal value inputted to the coefficient processing unit from each tap with a predetermined threshold level and changing the signal value and a coefficient value to be multiplied in accordance with the comparison result.

Abstract: A compensating circuit for compensating positive-negative asymmetry of an input signal having an amplitude exhibiting a positive-negative asymmetry with reference to a given level. Either one of the input signal or a signal obtained by multiplying the input signal by a given number is selected to be outputted as a compensated signal when the input signal has a level higher than a threshold level or alternatively when the input signal has a level lower than the threshold level. Distortion of signal waveforms ascribable to non-linearity of an MR head can be compensated satisfactorily with an extremely simplified and inexpensive circuit structure.

Abstract: A reproduced signal processing circuit includes a variable gain amplifier to which a signal read from a medium by a reproducing head is inputted; an analog-to-digital converter for converting a signal outputted from the variable gain amplifier into a digital signal; and a variable frequency oscillator for supplying an operation clock signal to the analog-to-digital converter.

Abstract: An information recording/reproducing apparatus includes first and second data demodulators having different data discriminating capabilities. The first data demodulator has a lower data discriminating capability and the second data demodulator has a higher data discriminating capability. When the reliability of reliability information for demodulation data generated by the first data demodulator, the second data demodulator is operated so that demodulation data generated by the first data demodulator is replaced by demodulation data generated by the second data demodulator during a period of time when the reliability of the reliability information is deteriorated.