Abstract: An energy dissipative element (24) protects hard disk drives (22, 72, 92) from shocks and vibrations. A closed elastic envelope (48) houses a body of open cell foam (54), a volume of viscous liquid (56), and a compressible gas (64). Under compression or expansion of the foam (54), viscous liquid (56) flows through cell orifices and thereby dissipates energy resulting from external force applied against the elastic wall (48). The energy dissipative elements (24) are applied between a disk drive housing (22) and an outer case (26) to create a ruggedized portable disk drive module (20).

Abstract: An energy dissipative element (24) protects hard disk drives (22, 72, 92) from shocks and vibrations. A closed elastic envelope (48) houses a body of open cell foam (54), a volume of viscous liquid (56), and a compressible gas (64). Under compression or expansion of the foam (54), viscous liquid (56) flows through cell orifices and thereby dissipates energy resulting from external force applied against the elastic wall (48). The energy dissipative elements (24) are applied between a disk drive housing (22) and an outer case (26) to create a ruggedized portable disk drive module (20).

Abstract: A programmable filter for the read channel of a magnetic recording device filters the sensed signals corresponding to data on magnetic media at at least two different transfer speeds of the magnetic media. The programmable filter, under microprocessor control, selectively switches its filter characteristics without affecting the quality of the filter but changing the cut-off frequency so as to correspond to the two different transfer speeds. The programmable filter of the present invention utilizes solid state switches to implement the switching of the filter characteristics to change the cut-off frequency without affecting the quality. The programmable filter is inductorless and is designed only with resistors and capacitors arranged in a filter network. The programmable filter does not use operational amplifiers, using instead low cost transistors in an emitter-follower configuration.

Abstract: A system for aligning data with corresponding sector marks in an optical disk storage system. In an optical disk storage system, data is written into a number of concentric bands, each of which contains a servo track and a number of data tracks. Each band is divided circumferentially into a series of sectors which are defined by marks in the servo track. The beginning of a sector is detected by identifying one of the marks in the servo track, and the beginning of a data record must coincide with the beginning of a sector. Recorded during the manufacture of the storage disk of the present invention, are pairs of special tracks wherein the first sector mark on a track is identified by an index mark, and the adjacent data track has a beginning of data mark recorded at a fixed location relative to the index mark. The disk read/write head is moved over one of these pairs and the difference in time between the occurrence of the index and occurrence of the beginning of data mark is measured.

Abstract: Disclosed is a data detection system and method for accurately detecting data transition marks recorded on a recording surface. A data transition pulse, generated by a data head as recorded data transition marks pass thereby, is presented to consecutive delay circuits in order to generate first and second delay pulses. The second delay pulse and the data transition pulse are subtracted from the first delay pulse, thereby creating a narrow output pulse that indicates the occurrence of a data transition. This narrow output pulse is used to toggle a flip-flop or equivalent logic circuit, the flip-flop output thereby representing a recreation of the data as recorded on the recording surface. The system is best suited for use with an optical storage system wherein data transitions are recorded on an optical disk as spots of substantially uniform size, although the detection system does not require that the spots be uniform size.

Abstract: A programmable signal equalizer uses a plurality of active RC circuits arranged to be controlled by a ladder resistor network. The resistor ladder circuits are selected by digital word signals representative of the selected magnetic tape speed to produce a signal equalization operation at each of the selected tape speeds. A combination of the ladder network circuits is selected by the digital bits in the digital word to form an active RC circuit producing a signal equalization correlated to a selected tape speed. Using an eleven line digital word code and an eleven RC ladder, eight master speed equalizations are selected as well as seven equalizations between the master speeds for a total of sixty-four equalization functions.