International Business Machines Corporation

Rolf Andresen

John H Christian

Sung J Kim

Alan L Murphy

Robert J Bellar

A liquid heat sink is provided that employs natural convection of a liquid coolant (18') to cool a printed circuit board (14) on which are mounted a plurality of heat-generating components (12). In particular, the spacing d between the heat-generating components and a cold plate (20) used to cool the liquid must be such as to provide a Rayleigh number of at least about 1700 in the Rayleigh equation: ##EQU1## In the above equation, g is the acceleration of gravity, .beta. is the volumetric coefficient of expansion of the liquid coolant, T.sub.1 is the temperature of the cold plate, T.sub.2 is the temperature of the component to be cooled, .nu. is the kinematic viscosity of the liquid coolant, and .alpha. is the thermal diffusivity of the liquid coolant. The novel heat sink of the present invention allows complete immersion of the component in the liquid to provide maximum heat transfer, while at the same time providing a mounting/packaging scheme that allows full utilization of the desired heat transfer properties.

Method and apparatus for immersion cooling or an electronic board

Improved conversion efficiency and lower output ripple are achieved by a DC-to-DC converter that uses an H-bridge driver to alternately energize first and second inductors. By alternately energizing the first and second inductors, a higher switching frequency can be maintained allowing for the use of smaller inductors while reducing ripple in the output voltage. The reduced ripple in turn reduces the need for filtering. Additionally, the first and second inductors are wound about a common core such that a mutual inductance exists therebetween. The mutual inductance results in trapezoidal currents in each inductor instead of the typical sawtooth waveforms. This results in still lower ripple in the output voltage.

H-driver DC-to-DC converter utilizing mutual inductance

A focus and tracking support includes a pair of bender beams extending parallel to a track to be scanned. The bender beams are cantilevered from a mounting block carried by a head carriage. Disposed intermediate and pivotally secured to the distal ends of the bender beams is a lens holder having two pairs of oppositely-extending, pivotally-secured support arms connected to the distal ends. The arrangement is such that when the bender beams are moved in the same direction tracking functions are performed while when the bender beams are moved in opposing directions, focussing functions are performed. The arms and lens holder are formed from a plastic unitary member. When the bender beams are piezo-electric beams, electrical signals for focus and tracking controls are superposed for effecting simultaneous focus and tracking functions.

Lens support system enabling focussing and tracking motions employing a

A disk file employs a disk having sectors of track-following servo information interspersed around the disk between data portions. Included in each sector is a SYNC signal which is encoded to indicate the validity or invalidity of the servo information in that sector. The servo information in a sector is used only if the SYNC signal indicates that it is valid.

Sector servo with sync marks

A record member is provided with a plurality of sector areas, including servo track follow integration areas. The integration areas comprise an equal number of signal bursts representing binary '1' and binary '0' in a predetermined arrangement to identify a plurality of record track location lines. The predetermined arrangement of '1's' and '0's' is generated by the insertion of one of two binary codes which exhibit high self-correlation properties, at positions within the integration areas corresponding to a consecutive number of signal bursts equal to a digit in the address identifying a particular one of the track location lines. The two binary codes are complements, are composed of an odd number of signal bursts and are selected so as to maintain equal the number of signal bursts representing binary '1' and binary '0', respectively, in the servo track follow integration areas. A transducer positioning circuit is provided which has a search mode for detecting addresses of the record track location lines and a servo mode for centering the transducer with respect to a selected one of the record track location lines.

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Tucson, AZ, United States of America

Rolf Andresen