Abstract: A digital circuit for detecting changes in the gray scale of scanned images is disclosed. Each line of video information produced by scanning the image is digitized. Each digital sample is compared to digital samples delayed a predetermined amount to generate a difference signal which is indicative of a change in the gray scale having a component perpendicular to the direction of scan. The digitized samples of the video signal are also stored in a memory having a capacity sufficient to store data representing a plurality of scan lines with a typical memory having a capacity for storing digital information representing eight scan lines. Selected digital samples from the stored data are compared to samples of the line being scanned to detect changes in the gray scale having a component parallel to the direction of scan.

Abstract: The preferred embodiment of the invention comprises a glass sealed thyristor and a method for simultaneously constructing a plurality of thyristors and a common semiconductor wafer. The thyristor utilizes a body of semiconductor material with the cathode and base regions extending to one major surface and the anode region extending to the second major surface. A groove is etched in the first surface of the body of semiconductor material to expose the PN junction formed at the interface of the cathode emitter and cathode emitter base regions. A second groove is etched in the second major surface to expose the PN junction formed at the interface of the anode emitter region and the anode emitter base region. Ring shaped glass members are fused to the body of semiconductor material to form seals providing environmental protection for the PN junctions exposed by etching the grooves in the major surfaces of the body of semiconductor material.

Abstract: A transistor in which this effective emitter resistance which is determined by the geometry of the emitter metallization as disclosed. In the preferred embodiment, the emitter metallization comprises a series of circular "dots" which are distributed over the entire emitter area. The area of the "dots" with respect to the entire emitter area is selected such that the desired effective emitter resistance is achieved.

Abstract: An asynchronous system for transmitting digital data from a data origination station to a data utilization station over a communications path such as an ordinary long-distance telephone network is disclosed. The system includes circuitry for synchronizing and maintaining synchronization between the receiving circuits and the transmitting circuits and for correcting errors introduced by the communications path. Each data word transmitted has associated therewith a synchronization code comprising a stop bit and a start bit. During normal operation, the system is synchronized by detecting the start bit which precedes the information portion of each data word. Synchronization is maintained for several data words even though the start bit is not detected due to interference, for example, by an auto-synchronization signal which includes a pulse positioned within the time period during which the start bit would normally be detected.

Abstract: An integrated array of solar cells, each cell having a positive and a negative electrode, is disclosed. A first grid comprising a plurality of non-intersecting electrically conductive members is affixed to an insulating substrate. Each single individual member of this grid forms the negative electrode of an individual cell of the array. Overlying and affixed to the negative electrodes and the surface of the substrate between these electrodes is a semiconductor layer of a first conductivity type. Isolated (i.e., non-touching or non-abutting) semiconductor regions of a second conductivity type form a plurality of PN junctions with the semiconductor layer. These P-N junctions are the active areas of the individual cells of the array. Each of the isolated semiconductor regions of the second conductivity type is solely coupled to an individual member of another grid whose members form the positive electrodes of the individual cells.

Abstract: An improved passive optical range simulator device which can be used to test the ranging function of an optical radar ranger system having parallel beams leaving and entering. An adapter member provides for mechanical coupling and optical alignment of the simulator device with the ranger system. A focusing lens transforms parallel beams entering and leaving the ranger system into focused beams entering and leaving one end of a coil of optical fiber having a mirror at its opposite end to act as an optical delay medium. A primary tilted-glass-element optical attenuator limits optical energy allowed to reach the optical fiber entrance face, while defecting first surface reflection away from ranger system input. A removable attenuator assembly having oppositely-tilted flat glass elements at the fiber entrance face permits, by substitution, fine adjustment of beam attenuation.

Abstract: A programmable test point selector circuit for interfacing a test set with a system to be tested is disclosed. Typically, the system to be tested is provided with a multi-pin connector or receptacle to which the automatic test set is connected. The disclosed programmable test point selector circuit is interposed between the test set and this connector. Digital program words from the test set are used to designate pins of the multi-pin connector for use as either an input pin or an output pin. Additionally, the programmable test point selector permits at least one voltage level of the digital signal supplied to any pin designated as an input to be independently programmed over a wide range of values. An output sensing circuit is also provided which permits any individual pin or group of pins to be selected for monitoring to determine the voltage level of the signal present at the selected output pin relative to a threshold level.

Abstract: A method for etching semiconductor fusions to change their electrical characteristic, especially to reduce the firing current of thyristor fusions, to a predetermined desired value is disclosed.The etching is accomplished by subjecting fusions comprised of a body of semiconductor material, for example, silicon, including an anode emitter region therein and an anode electrode affixed thereto, an anode base region, a cathode base region and a gate electrode affixed thereto, and a cathode emitter region having a cathode electrode affixed thereto, to a plasma etchant comprising a mixture of CF.sub.4 and a carrier gas such for example, nitrogen, for a predetermined time interval. Following this etching cycle the firing current of the fusions is measured. Any fusions having a firing current in excess of the desired value at the end of the first etching cycle are subjected to another etching cycle to further reduce the firing current.

Abstract: A glass encapsulated semiconductor diode and a method for glass encapsulation of a fusion to form a semiconductor diode is disclosed. The fusion comprises a body of semiconductor material having a PN junction therein and metal electrodes affixed to opposed major surfaces thereof. The fusion is encircled by a ring-shaped glass member with an inner surface of the ring-shaped glass member fused to an edge surface of the body of semiconductor material to form a protective layer overlying the PN junction. The ring-shaped glass member is formed and fused to the edge of the body of semiconductor material by placing the fushion and a prefabricated glass ring, preferably cut from stress relieved glass tubing, encircling the fusion in a furnace. A weight is applied to the upper surface of the prefabricated glass ring.

Abstract: A signal simulator for generating a simulated target signal useful in testing the receiver and data processing portions of radar systems is disclosed. Input signals to the signal simulator include a multi-pulsed synchronizing signal having substantially the same duty cycle and PRF (pulse repetition frequency) as the RF output signal of the radar transmitter normally used in conjunction with the receiver, digital signals specifying the acceleration, the initial velocity and the initial range of the target to be simulated. A target range calculator circuit utilizes the acceleration, initial velocity and initial range signals to calculate the range of a simulated target. A plurality of delay circuits are sequentially initialized by the synchronizing signal to generate a trigger signal delayed from the synchronizing signal with the delay corresponding to the range of the simulated target. The pulse width of each pulse of the synchronizing signal is measured and stored.

Abstract: A glass sealed semiconductor diode is disclosed. The diode includes a fusion which comprises a body of semiconductor material having a PN junction therein and metal electrodes affixed to opposed major surfaces of the semiconductor body. The fusion is encircled by an annular-shaped glass member with an inner surface of the annular-shaped glass member fused to an edge surface of the fusion to form a protective layer over the PN junction. An annular metallic member encircles the annular glass member with an inner surface thereof fused to an outer surface of the annular glass member.

Abstract: A radiation hardened drain-source protected MNOS transistor is disclosed. A layer of silicon oxide overlies the channel and the junctions formed by the intersections of the drain and source regions with the channel. Drain and source protection is provided by relatively thick portions of the silicon oxide layer which overlie the junctions formed by the drain and source regions and the channel. The portion of the silicon oxide layer overlying the central section of the channel is thinner than the remainder of this layer.A silicon nitride layer and an electrically conductive layer forming the gate electrode overlie the thinner portion of the silicon oxide layer to complete the MNOS transistor. The conductive layer forming gate electrode of the transistor is in electrical contact with both the silicon nitride and the silicon oxide layers.

Abstract: A digital circuit for detecting changes in the gray scale of scanned images is disclosed. Each line of video information produced by scanning the image is digitized. Each digital sample is compared to digital samples delayed a predetermined amount to generate a difference signal which is indicative of a change in the gray scale having a component perpendicular to the direction of scan. The digitized samples of the video signal are also stored in a memory having a capacity sufficient to store data representing a plurality of scan lines with a typical memory having a capacity for storing digital information representing eight scan lines. Selected digital samples from the stored data are compared to samples of the line being scanned to detect changes in the gray scale having a component parallel to the direction of scan. These detected changes in the gray scale are combined to generate a signal which operates a printer to generate a line drawing of the scanned image.

Abstract: This invention relates to a semiconductor device having as a part thereof a second semiconductor device to protect the first or main device against overheating and current overloads.

Abstract: An altitude simulator for checking the range accuracy of a radar altimeter is disclosed. Typical altimeters include a transmitter and a receiver. The simulator receives a multipulse trigger signal from the altimeter to be checked. The trigger signal is synchronized with the output pulses of the transmitter. This trigger signal forms an input to a phased locked loop to generate at the output of the phased locked loop a multipulse signal which is synchronized with and phase displaced from the trigger signal by an amount equal to the inherent time delays in the simulator. The output signal of the phase locked loop is coupled to the input of a pulse generator which is programmable to generate a multipulse output signal synchronized with and phase displaced from the output signal of the phase locked loop by a selected fixed amount. A modulator receives an RF input from a signal generator and the ouput signal of the pulse generator to produce at the output of the modulator a pulse modulated RF signal.

Abstract: A monitoring circuit for digital circuits is disclosed. The monitor is primarily applicable to digital circuits which operate in a cyclic mode with the digital patterns generated during each cycle being repeated in a predictable manner. A predetermined number of expected bit patterns are stored in a programmable memory. The stored bit patterns correspond on a bit-by-bit basis to the bit patterns generated by the circuit being monitored when this circuit is operating normally. In the self-scan mode each pattern generated by the circuit being monitored is compared to each of the patterns stored in the memory in a sequential manner. Each time a pattern generated by the circuit being monitored is found to identically correspond to a pattern stored in the memory a valid pattern pulse is generated which steps a down counter one count.

Abstract: A nonvolatile (MNOS) memory array using varactor boosted select signals is disclosed. The memory utilizes a varactor circuit to boost the row select during the erase and write modes of operation.

Abstract: A digital monitor for monitoring the operation of a synchronous digital system. Proper operation of the monitored digital system is determined by storing a predetermined sequence of digital numbers in a memory. The bit patterns generated by the system being monitored are utilized as addresses to read the stored digital numbers. After each read cycle the digital number read from the memory is examined to determine if it has the proper value. If the value is not proper, a memory is set indicating that the system being monitored has malfunctioned. Additionally, the number of bit patterns checked during each cycle of the system is determined. If the correct number of patterns are not checked, the memory is also set indicating that a malfunction has occurred. Apparatus for monitoring a selected number of analog signals such as power supply voltages is also provided. Either of these tests may be inhibited by signals from the system being monitored or by signals from an external source.

Abstract: A reverse switching rectifier is described in which a PNPN semiconductor structure has a specially adapted N-type end zone or cathode-emitter zone. The N-type end zone penetrates to two different levels in the semiconductor body. A deep central portion and a shallow peripheral portion of the N-type end zone are produced by etching a cavity in the center of the body followed by diffusion of N-type dopant material. The exposed surfaces of the N-type end zone are then metallized to provide electrical and thermal contact thereto.

Abstract: A device for substantially instantaneously converting a tonal image, such as a photograph, to a line drawing which depicts the lines formed by the borders of contrasting portions of the tonal image. The tonal image is scanned by a video scanner to produce a time varying video signal which signal is then differentiated to produce a signal consisting of pulses representative of predetermined selected levels of changes in tone, color, or shade. The signal is supplied to a pulse generator which produces a pulse of uniform width and height for each input pulse suitable for processing by a video receiver. The video receiver, being synchronized with the video scanner, is provided with means to instantaneously display a line drawing of the tonal image. Circuit control means are also provided to vary the uniform width of the lines in the resulting line drawing and to control the selection of lines in the line drawing in accordance with its corresponding significance in the tonal image.