Abstract:
PROBLEM TO BE SOLVED: To provide a sync mark detecting method for using information from a preamble and codes of sampled data to increase the fault tolerance of a sync mark detector.SOLUTION: Digital data have a preamble field, the following synchronization mark succeeding to the field, and a data field succeeding to the mark. The timing recovery (28) of a reading channel synchronizes a phase and a frequency of the preamble field, and a synchronization detector (A120) detects the synchronization mark and frames an operation of an RLL decoder (36, A122) for decoding the detected data field. The synchronization mark is selected to meet conditions that a correlation with the shifted synchronization mark connected to the preamble field is minimum in order to reduce a possibility of early erroneous detection. The synchronization mark detector is enabled by timing recovery relative to the end of the preamble field in order to further increase the fault tolerance.
Abstract:
PROBLEM TO BE SOLVED: To provide a low-cost, more efficient magnetic disk servo control system that compensates for non-linear gain variations associated with MR read heads. SOLUTION: A position error X149 is multiplied by a positive gain 47 or a negative gain 48 depending on the state of a switch 46 to generate an acceleration command U53 as input to the controlled system 44. The output of an integrator 54 is the velocity of a controlled system which is also the negative -X255 of the position error velocity. When the switch 46 selects the positive gain 47, it is a negative feedback system, and when the switch 46 selects the negative gain 48, it is a positive feedback system. In each of the structures, the system is unstable. However, the system can be made stable by repeatedly switching between the two structures. COPYRIGHT: (C)2009,JPO&INPIT
Abstract:
PROBLEM TO BE SOLVED: To adaptively reduce dead time in a switching circuit (305). SOLUTION: An apparatus for adaptively reducing dead time in a switching circuit includes: overlap detection circuitry (310) for measuring (406) the dead time/overlap of switches (104, 105); and control circuitry (320) for setting (408) the dead time to the optimum level (407) (generally the minimum possible dead time without any overlap occurring). The dead time/overlap may be detected by measuring the current through switches (501), the current into a power supply (601), the voltage waveform (710, 711, 712) at the switch point, or the average voltage waveform (803) at the switch point. The dead time may be controlled by utilizing delay elements (902, 903) prior to drivers (302, 303) or by utilizing circuitry (302a/320b) to control the driver timing. COPYRIGHT: (C)2010,JPO&INPIT
Abstract:
PROBLEM TO BE SOLVED: To provide an optical disk drive servo control system in which sensitivity to a change in parameter is not so high, and transition can be controlled more favorably and the implementing cost of a complex adaptive linear controller is eliminated. SOLUTION: The optical disk storage system is provided with a sliding mode controller for actuating an optical lead head assembly on an optical disk during focus capturing, focus tracking, track seeking and centerline tracking. The sliding mode controller operates by switching feedback between a positive state and a negative state so as to follow a predetermined phase state track by allocating a certain phase state (e.g., position error or speed of the lead head). COPYRIGHT: (C)2009,JPO&INPIT
Abstract:
PROBLEM TO BE SOLVED: To provide a sliding mode controller for controlling the motion of a magnetoresistive (MR) read head actuated by a voice coil motor over a rotating magnetic disk storage medium. SOLUTION: The magnetic disk 4 includes a plurality of concentric data tracks recorded on the surface, and each data track includes user data and servo data. The sliding mode controller 26 operates by multiplying a head position error phase state and a head position error speed phase state by respective switching gains to force the phase states to follow a predetermined phase state trajectory. The phase state trajectory is defined by a single linear segment , a variable linear segment, multiple linear segments over the entire region of excursion, or optimal parabolic acceleration and deceleration segments. COPYRIGHT: (C)2010,JPO&INPIT
Abstract:
PROBLEM TO BE SOLVED: To provide an output circuit capable of generating an output signal with a relatively high voltage level from a chip manufactured by a process in a relatively low voltage level. SOLUTION: The output circuit has a control-signal logic circuit, a pseudo-ground generating circuit, and an output-signal generating circuit. The control-signal logic circuit receives three-volt data signals from an internal logic circuit in the chip, and generates a control signal as the function of these three-volt data signals. The pseudo-ground generating circuit is connected to the control-signal logic circuit to generate the pseudo-ground level higher than a zero volt and an intermediate output signal, as the function of the control signal generated by the control-signal logic circuit. The output-signal generating circuit is connected to the pseudo-ground generating circuit to generate a five-volt output signal, as the function of the intermediate output signal generated by the pseudo-ground generating circuit. A difference in voltage level in a semiconductor device inside the output circuit always shows below five volt due to generation of the pseudo-ground level. COPYRIGHT: (C)2009,JPO&INPIT
Abstract:
PROBLEM TO BE SOLVED: To provide an efficient error correction processor for correcting a multi-dimensional code comprising a first set of codewords that intersect with a second set of codewords. SOLUTION: The error correction is carried out by performing iterative passes over the first and second sets of codewords. The individual codewords are corrected using error syndromes which are computed as a function of the codeword data. In the preferred embodiment, the individual codewords are encoded according to a Reed-Solomon code and the error syndromes are computed as the modulo division of the codeword polynomial by the factors of a generator polynomial. To increase the throughput of the error correction processor, a syndrome buffer is employed to facilitate generating the error syndromes for both the first and second sets of codewords concurrently. In this manner, after a pass over the first set of codewords, the error syndromes for the second set of codewords are available for immediate processing. COPYRIGHT: (C)2008,JPO&INPIT