Patents Represented by Attorney Leonard Zalman
  • Patent number: 3979586
    Abstract: An erasable optical memory array having at each storage location a non-crystalline, semiconductor threshold switching device. The threshold voltage of each switching device is strongly temperature dependent and each switching device has a finite recovery time when switched to its low resistance state. Means are provided for periodically sampling each of the switching devices with voltage pulses repetitive at a first frequency and having a first voltage level sufficient to switch to the low resistance state only those switching devices heated above room temperature by a thermal image. Additional means are provided to sample the switching devices at a second frequency greater than the first frequency and at a voltage level less than that of the first voltage level to maintain the switched devices in the low resistance state upon removal of the thermal image.
    Type: Grant
    Filed: December 9, 1974
    Date of Patent: September 7, 1976
    Assignee: Xerox Corporation
    Inventor: David D. Thornburg
  • Patent number: 3979568
    Abstract: A switching device having a movable contact that is an integral part of a metallic support substrate and is supported above the support substrate by a plurality of spring-like support legs that are also an integral part of the support substrate. The support legs extend radially outward from the movable contact and contact the substrate and the movable contact at equally spaced points. The movable contact is aligned with either a stationary contact or another movable contact and a stationary contact to provide either single or multiple switching. The switching device can be used for contact switching or capacitive switching. A plurality of the switching devices can be formed on the support substrate making the switching device particularly well suited for use in a keyboard. A portion of each support leg may be thinned to provide a negative force-displacement characteristic which provides a good tactile feedback signal indicating switching.
    Type: Grant
    Filed: September 23, 1974
    Date of Patent: September 7, 1976
    Assignee: Xerox Corporation
    Inventor: Wendell C. Johnson
  • Patent number: 3978428
    Abstract: A buried-heterostructure (BH) diode injection laser capable of operating at low room temperature thresholds and in the lowest order TE, TM or TEM modes. The laser has an elongated groove in a substrate with the groove extending through a pump current confining layer with a central portion of the active layer substantially completely within the groove and substantially completely surrounded by light guiding and carrier confining layers of material having a lower index of refraction than the index of refraction of the material of the active layer. The light guiding and carrier confining layer in contact with the substrate has a central depression within the elongated groove and the central portion of the active layer is bowl-shaped and within the depression such that light waves produced by carrier recombination within the central portion of the active layer when the laser is forward biased are guided in the central portion of the active layer such that the laser produces a light beam having reduced width v.
    Type: Grant
    Filed: June 23, 1975
    Date of Patent: August 31, 1976
    Assignee: Xerox Corporation
    Inventors: Robert D. Burnham, Donald R. Scifres
  • Patent number: 3974905
    Abstract: A key arm mechanism for keys of a typewriter or data entry device in which a uniform spring rate is achieved by varying the cross-sectional area of the key arms as a direct relation to the distance of the key support posts from a cantilever point. The entire key arm mechanism is formed of a unitary molded material. In one embodiment, the cross-sectional area of each key arm is uniform from the cantilever point to its associated key support post. In another embodiment, the cross-sectional area of each key arm decreases linearly from the cantilever point to its associated key support post. Uniform initial preload tension can be applied to the key arms by a slotted member which engages the ends of the key arms remote from the cantilever points. Non-uniform preload tension can be achieved by varying the height of some slots of the slotted member or by varying the height of the key arms at the ends thereof remote from the cantilever points.
    Type: Grant
    Filed: September 23, 1974
    Date of Patent: August 17, 1976
    Assignee: Xerox Corporation
    Inventor: Wendell C. Johnson
  • Patent number: 3975755
    Abstract: A switching device having as the active switching element a material with a band gap between 0.6 and 1.2 eV and a mean coordination number of 4. These parameters provide a material having a glass transition temperature that is relatively high such that the material is resistant to devitrification. Amorphous (a-) CdAs.sub.2 is the most promising active switching material having the parameters, and a method of making thin films of a-CdAs.sub.2 by open source evaporation is disclosed.
    Type: Grant
    Filed: March 17, 1975
    Date of Patent: August 17, 1976
    Assignee: Xerox Corporation
    Inventor: David D. Thornburg
  • Patent number: 3974906
    Abstract: A ribbon cartridge for a printer provides an unsupported length of ribbon between a pair of spaced guide means to provide for easy threading. In addition, continuous rotation of the ribbon is made possible by storing the ribbon as an endless loop in a random fashion in the principal cavity of the cartridge. A secondary cavity prevents an accidental loop from coming out of the cartridge which would otherwise result in slack in the unsupported length.
    Type: Grant
    Filed: February 25, 1972
    Date of Patent: August 17, 1976
    Assignee: Xerox Corporation
    Inventors: Sen Lin Lee, Ernst Peter Hess
  • Patent number: 3970958
    Abstract: A distributed feedback, (DFB) electrically pumped diode laser in which the spacing of the periodic structure within the diode is selected to optimize the interaction between the periodic structure and the electromagnetic waves in the diode laser. The degree to which the waves interact with the periodic structure is described mathematically by a coupling constant K, with larger values of K corresponding to lower gains required to produce laser operation. It is shown that in DFB diode lasers higher order transverse modes have a higher coupling constant K with the periodic structure than does the lowest order transverse mode and thus the higher order transverse modes will lase more easily than the lowest order transverse mode.
    Type: Grant
    Filed: October 15, 1974
    Date of Patent: July 20, 1976
    Assignee: Xerox Corporation
    Inventors: William Streifer, Donald R. Scifres, Robert D. Burnham
  • Patent number: 3969595
    Abstract: A multiple switching apparatus comprising two spring-like switching members disposed in a tandem array with each integral with its metallic support base. The central area of each of the switching members is defined by a plurality of slots formed in the support base with the length and displacement of the slots defining the force-displacement characteristics of each switching member and, accordingly, of the tandem array. The top switching member moves downward until it produces a first switching function, with further movement of the top switching member effecting movement of the second switching member such that a second switching function is produced.
    Type: Grant
    Filed: September 23, 1974
    Date of Patent: July 13, 1976
    Assignee: Xerox Corporation
    Inventor: Wendell C. Johnson
  • Patent number: 3969686
    Abstract: An electrically pumped, distributed feedback laser having all side surfaces of the active laser medium cleaved and a periodic structure at a 45.degree. angle to all of the cleaved surfaces. Current confining channels restrict pumping current to selected regions of the active laser medium to provide sufficient feedback such that two parallel filamentary areas of the active medium lase. By having multiple lasing filaments the divergence of the output beam in the direction of the width of the filaments is reduced by a factor proportional to the number of filamentary lasing areas.
    Type: Grant
    Filed: March 26, 1975
    Date of Patent: July 13, 1976
    Assignee: Xerox Corporation
    Inventors: Donald R. Scifres, Robert D. Burnham, William Streifer
  • Patent number: 3968336
    Abstract: A switching device having a movable contact element characterized by a set of unconnected, curved slots radiating outward from a central key area and equally spaced around the central key area. The radially extending unconnected, curved slots may be sections of a spiral, at least some of which sections overlap each other. Adjustment of the spring rate of the movable contact element is accomplished by adjusting the length of the slots or by regulating the distance of the inner terminus of the slots from a central point of the central key area. The movable contact element either contacts a second contact element for contact switching or approaches the second contact element for capacitive switching.A plurality of the switching elements can be formed in a planar array on a continuous metallic substrate to provide a keyboard. The movable switching elements can be formed on the metallized areas of a printed circuit board.
    Type: Grant
    Filed: September 23, 1974
    Date of Patent: July 6, 1976
    Assignee: Xerox Corporation
    Inventor: Wendell C. Johnson
  • Patent number: 3956042
    Abstract: A method of making thin film devices with selective etchants. Specifically, a fabrication process in accordance with the invention provides for the manufacture of amorphous chalcogenide sandwich structures. Such structures consist of a glass substrate, a chromium or aluminum electrode on the substrate bounding one side of the chalcogenide layer, and a second electrode of aluminum bounding the other side of the chalcogenide layer. First, the aluminum electrode is etched without affecting the other layers. Secondly, the chalcogenide layer is etched with a solution which attacks only the chalcogenide material and neither the overlying aluminum nor the underlying chromium or aluminum electrode. This two-step process is particularly suitable for fabricating current controlled negative differential resistance devices which requires the precise registration of one of the electrodes with the boundary of the chalcogenide such that a coextensive boundary is achieved.
    Type: Grant
    Filed: November 7, 1974
    Date of Patent: May 11, 1976
    Assignee: Xerox Corporation
    Inventors: David D. Thornburg, Richard I. Johnson
  • Patent number: 3954534
    Abstract: A structure for providing arrays or individual hemispherical diodes and methods of producing the diodes. When the diode array is to be part of a configuration utilizing a substrate, the substrate is selected to have radiation transparency, a lower refractive index, and lattice constant and lattice structure similar to that of a crystal layer grown in hemispheres formed in the substrate. When the diode array is to be removed from the substrate, a material that can be preferentially etched is grown between the hemispheres formed in the substrate and the grown crystal layer that is to have light emitting areas.
    Type: Grant
    Filed: October 29, 1974
    Date of Patent: May 4, 1976
    Assignee: Xerox Corporation
    Inventors: Donald R. Scifres, Robert D. Burnham
  • Patent number: 3953708
    Abstract: A thermal printer comprised of a shift register, a line buffer and a plurality of printheads in heat-transfer relationship with a heat-sensitive record medium. The shift register and line buffer are comprised of a plurality of stages or modules with each module having an amorphous semiconductor heating element that exhibits current controlled negative differential resistance in heat-transfer proximity to a heat-gated amorphous semiconductor threshold switch which has a V-I characteristic which is strongly temperature dependent. The printheads are comprised of the amorphous semiconductor heating elements. Data is stored in the shift register by means of a video data signal and two oppositely phased clock signals of an amplitude that will only bias a heated threshold switch to conduction, with transfer of data to the line buffer being achieved in a parallel format by a third properly phased clock signal.
    Type: Grant
    Filed: April 25, 1975
    Date of Patent: April 27, 1976
    Assignee: Xerox Corporation
    Inventor: David D. Thornburg
  • Patent number: 3952156
    Abstract: A system for processing a plurality of audio signals to generate binaural output signals. The signal processor has a manually operated spatial position control which provides a correspondence between movement of the control and the binaural perception of movement by a listener at a listening position within an audio signal space. The spatial position control is essentially an electric circuit analog of a particular audio signal space, with means for obtaining variable binaural output signals from the circuit to simulate movement of the listening position in the signal space. One embodiment of the position control includes a mechanical linkage to a plurality of series ring connected potentiometers. The variable outputs from the wiper arms of the potentiometers are combined to produce the desired binaural output signals. The perceived orientation of the listening position in the audio signal space may be changed by selective combinations of potentiometer outputs.
    Type: Grant
    Filed: September 7, 1972
    Date of Patent: April 20, 1976
    Assignee: Xerox Corporation
    Inventor: Roy J. Lahr
  • Patent number: 3950846
    Abstract: A method of forming a switching device having a movable contact that is an integral part of a metallic support substrate and is supported above the support substrate by a plurality of spring-like legs that are also an integral part of the support substrate. One or more of the switching devices is produced by forming one or more groups of curved, unconnected radially extending slots in a metallic substrate to define support legs, plastically deforming the legs defined by the slots past their elastic limit, and then precipitation hardening the complete structure. The slots can be formed by a photomasking technique followed by an acid etch with the etch being performed from both sides of the metallic support substrate. To provide a desired tactile response characteristic, and to assure movement of a central portion of the switching device past the plane of the metallic support substrate, a portion of each of the legs defined by the slots may be removed to thin that portion of each leg.
    Type: Grant
    Filed: September 23, 1974
    Date of Patent: April 20, 1976
    Assignee: Xerox Corporation
    Inventor: Wendell C. Johnson
  • Patent number: 3947390
    Abstract: A switching plate having a plurality of arch-shaped snap-type switching members formed in a continuous metallic sheet or from sections of a metallic sheet bonded to an insulating substrate. Adjacent of the switching members extend in transverse directions. The switching members will snap downward when forced sufficiently downward thereby achieving contact or capacitive switching.The switching members are formed in a metallic sheet by providing a first plurality of groups of parallel slots in one direction and a second plurality of groups of parallel slots in a transverse direction, one of the slots of the first group being longer than the other slots. The sheet is placed in a die having members conforming in shape to the desired arches, wherein the sheet is deformed elastically at desired locations to provide the arch-shaped snap-type switching members.
    Type: Grant
    Filed: September 23, 1974
    Date of Patent: March 30, 1976
    Assignee: Xerox Corporation
    Inventor: Wendell C. Johnson
  • Patent number: 3946222
    Abstract: A system for automatically focusing images of different magnifications to be reproduced onto a light sensitive medium. First and second optical patterns of a wavelength to which the light sensitive medium is not responsive are projected from first and second displaced light pattern producing means to the projection plane of the images to be reproduced and back to the light pattern producing means. The light pattern producing means have transparent portions therein such that when the returned optical patterns are defocused portions of the defocused optical patterns are transmitted through the transparent portions. The transmitted light is then mechanically modulated and then converted to an electrical signal which is amplified, filtered and then demodulated to provide a signal having the polarity needed to drive a servo system such that focus of the images to be reproduced is achieved.
    Type: Grant
    Filed: April 18, 1975
    Date of Patent: March 23, 1976
    Assignee: Xerox Corporation
    Inventor: Melvin E. Swanberg
  • Patent number: 3940574
    Abstract: Reproducing the information stored in the spiral track of a record-type information-bearing disc is achieved by uniformly charging the surface of the disc by means of a corona-generating device disposed in proximity to the disc, and, thereafter, using a conductive stylus riding in the track of the disc to pick up the charge from only the peak points of the track. All peaks are at the same height. The system preferably uses FM encoding, and the information is carried by the track according to the peak-to-peak spacing. The stylus is shaped in relation to the track such that it may not touch the peaks in the track. The stylus contacts the sides of the track for tracking purposes. An air breakdown between the peaks and the metallic portion of the stylus results in the signal picked up by the stylus.
    Type: Grant
    Filed: December 20, 1973
    Date of Patent: February 24, 1976
    Assignee: Xerox Corporation
    Inventor: Leland Dale Green
  • Patent number: 3938881
    Abstract: An acousto-optic modulation device is provided which is comprised of an interaction material of an injection moulded plastic integrally combined with a transducer which is bonded automatically to the interaction material during the injection process. A beam of light is projected through the interaction material, the light being diffracted by an acoustic field established by the transducer.
    Type: Grant
    Filed: November 25, 1974
    Date of Patent: February 17, 1976
    Assignee: Xerox Corporation
    Inventors: David K. Biegelsen, Gary K. Starkweather, James C. Zesch
  • Patent number: 3936180
    Abstract: A printing system adapted for creating hard copy output from computer generated digital pulses. This system feeds blank or preprinted paper from a paper supply station through a xerographic processor wherein readable computer generated images are created thereon. The information bearing paper is then transported to a paper receiving station which comprises one or more paper receiving bins. Alternatively, an auxiliary feed path for the output paper is created to direct pages, under certain circumstances, to a sample print tray. Paper deflecting fingers are provided to divert pages to the sample print tray under the control of the operator in response to one of four conditions. These conditions include: (a) The feeding of a sample page through the processor when power is first applied to the machine after the machine has been in a powerless state, or (b) After a jam in the system has been cleared and it is desired to abort pages which have not been removed from the paper path.
    Type: Grant
    Filed: January 4, 1973
    Date of Patent: February 3, 1976
    Assignee: Xerox Corporation
    Inventors: Charles F. Willard, Brian D. Marsden, John G. Richardson, James L. Gastonguay