Drexler Technology Corporation

Etak, Inc.

Sony Corporation

Teleatlas North America Inc

City of Seattle, the City Light Dep't.

James L Buxton

Gerald A Pierce

Richard Frederick Poppen

Alan C Phillips

Rodney Jude Fernandez

Norman A Peppers

Stanley K Honey

Warren J Vinzant

A system for computing a path in an electronic map (or other network) starts a pathfinding exploration in the background while the system is waiting for a request to find a path. The system automatically chooses an origin. The system's memory can be divided such that a portion of memory acts as a cache. The data for the nodes in the electronic map are loaded into the cache when needed. The system terminates the pathfinding process when a predetermined condition occurs; for example, a predetermined percentage of the cache is filled. When the system terminates the pathfinding process, the system can start a new pathfinding process from a new origin. Thus, when a user requests a path to be found, the pathfinding process begins with data already loaded in the cache.

Caching for pathfinding computation

An optical data storage and retrieval system using a length of optical recording material in which data in the form of microscopic spots is disposed in cells forming a regularly spaced grid. While the material is being moved in a lengthwise direction by a transport, rows of cells are being read by a linear CCD array, one row at a time. A servo system advances the material so that successive rows can be read, while a second servo adjusts the position of the material in the crosswise direction for proper alignment with the CCD array.

Transmissively read quad density optical data system

An optical data read-only card and system using a length of optical recording material in which data in the form of microscopic spots is disposed in cells forming a regularly spaced grid. The spots contrast with the background media with a reflective contrast ratio of at least 1.5 to 1. While the material is being moved in a lengthwise direction by a transport, rows of cells are being read one row at a time by a linear CCD array capable of detecting the contrasting reflectivities between spots and background.

Read-only optical card and system

A method and apparatus for generating a stroke on a display comprising a pair of pulse train generators coupled to a pair of charge pump and integrator assemblies by means of a switch assembly. In operation, a first pulse train corresponding to the larger of the X and Y components of the stroke and a second pulse train corresponding to the ratio of the X and Y components of the stroke control the magnitude of the output of the charge pump and integrator assemblies.

Method and apparatus for generating a stroke on a display

Quad density optical data system

A servo tracking system for an optical record uses a pattern of preformed optically detectable uniform servo track marks disposed in parallel spaced apart columns in combination with a beam from a radiation source split by a diffraction grating into three beams having unequal power distribution. The placement of the beams across the pattern of preformed servo tracks on an optical recording material has one position for writing data by the center beam on an information track while the two outside beams intercept track marks on two adjacent tracks. For reading recorded data tracks, the beams shift to a second position in which the center beam intercepts marks on a servo track while the two outside beams read two adjacent data tracks. Because of the unequal power distribution, increasing the energy level of the radiation source causes the intensity of the middle beam during recording to reach a level sufficient to record while the two outside tracking beams remain below that threshold. The track marks in adjacent columns may be in an offset position with regard to track marks of the adjoining column, to provide self-clocking during recording.

Three-beam optical servo tracking system with two-track parallel readout

A skew correction system for data media, especially optical data storage media wherein a pair of identical geometric marks are spaced apart in a band or track parallel to a data track, the data tracks being transverse to the directions of relative motion of the data storage medium with respect to a detector. As the medium moves relative to the detector, a linearly scanning detector, portions of each geometric mark are observed by the detector. A ratio of picture elements is determined using the two sets of observed picture elements. If the ratio is other than 1, skew exists. A closed-loop servo system is used to restore the ratio to 1, thereby eliminating skew. The geometric marks may be disposed forward of the data tracks, astride the data tracks, behind the data tracks, interspersed with the data tracks, or if different colors of light are used, atop the data tracks.

Skew detection system for optically read data

An inductance coil is clamped onto the cable which is to be monitored. For normal line currents, the coil produces a signal voltage which charges a reset capacitor which in turn periodically discharges to an indicator to show a no fault condition. When the line current goes above a predetermined fault level and remains at that level for a corresponding fault time period, the coil develops a signal voltage sufficiently high to charge a 'set' capacitor that discharges to the indicator to show a fault condition. The indicator continues to show the fault condition until normal current has returned to cause the 'reset' circuit to operate to indicate no fault. To insure that the set capacitor discharges in a manner to indicate reliably the fault condition, there is provided a voltage responsive variable impedence in the circuitry to charge the set capacitor. This variable impedence matches the fuse characteristic in the main power line.

Growing community of inventors

East Palo Alto, CA, United States of America

James L Buxton