Abstract: Liquid crystal displays having improved apparent viewing cones are disclosed. The displays are activated by an electrical energizing signal which comprises an activation signal portion and a superimposed A.C. voltage signal by which the apparent viewing cone angles of the displays are increased.

Abstract: A gain control and signal conversion stage in a data converter for a color video CRT display system is disclosed. The disclosed circuit includes capacitors for supplying current at a selected output voltage level, voltage followers for charging the capacitors, and modulators for forming low-level analog color signals for control of video amplifiers in a color CRT display. Digital control of video brightness or contrast and precise color tracking are features which are discussed.

Abstract: A data processing system employing broadcast packet switching and having a plurality of subsystems and a system bus for linking the subsystems. The subsystems are grouped within stations that are each enclosed by a computer cabinet. The system bus includes a star coupler, first and second external transmission lines connecting each station to the star coupler, and first and second internal transmission lines within each station that are coupled to the first and second external transmission lines. The subsystems within each station are each coupled to the first and second internal transmission lines by a system bus interface. The system bus interface monitors the system bus for an idle condition, and passes a message from its subsystem to the system bus only when it detects an idle condition on the system bus. Each message on the system bus includes a postamble that is garbled by any system bus interface that detects an error in any message on the system bus.

Abstract: A process for treating the interior surface area of a glass nozzle for use in an ink jet printer device. The process includes cleaning of the surface area with a hydrofluoric acid solution under controlled conditions, rinsing and then protecting the cleaned area with a blocking agent to prevent contamination by the atmosphere prior to use of the nozzle in a printer device. The disclosed process is useful in minimizing air bubble formation and lock within the nozzle during use, and in facilitating ejection or purging of such air bubbles as may become ingested by the nozzle during service.

Abstract: Described is a controlled device such as a printer device, comprising an electrically operated mechanism such as a moveable print head, a scanner for sensing indicia of alignment of the electrically operated mechanism, and an electrical conductor to carry signals by which the mechanism is operated. The electrical conductor is employed to provide the indicia of alignment to be read by the scanner. Included is a description of an electrical conductor which comprises parallel conductive runs made of copper which are spaced apart and supported by a transparent electrically insulative plastic material, thus forming a timing strip on which positional indicia are defined by optical contrast between the runs and the insulative plastic material.

Abstract: A data processing system employing broadcast packet switching and having a plurality of subsystems and a system bus for linking the subsystems. The subsystems are grouped within stations that are each enclosed by a computer cabinet. The system bus includes a star coupler, first and second external transmission lines connecting each station to the star coupler, and first and second internal transmission lines within each station that are coupled to the first and second external transmission lines. The subsystems within each station are each coupled to the first and second internal transmission lines by a system bus interface. The system bus interface monitors the system bus for an idle condition, and passes a message from its subsystem to the system bus only when it detects an idle condition on the system bus. Each message on the system bus includes a postamble that is garbled by any system bus interface that detects an error in any message on the system bus.

Abstract: Described is a piezoelectric drive element assembly for use in ink jet printer devices. The assembly comprises a piezoelectric drive element, which is characterized by a pair of electrodes spaced apart and thereby electrically isolated from one another on an external lateral face of the drive element. The assembly further includes a printed circuit board having holes through which the drive element is fitted, with the electrodes of the drive element being soldered to opposite sides of the printed circuit board.

Abstract: A method and apparatus for simulating custom chips to be used in a data processing system. Each chip is simulated by a chip simulator that includes a mother board and a plurality of baby boards mounted and interconnected on the mother board. Each baby board has circuit components mounted thereon for performing the circuit function of one cell of the chip. Chip simulators are interconnected in an interconnecting apparatus that supports the mother boards in parallel and spaced apart relation. Chip simulators that represent all of the chips found on a single printed circuit board in the system are interconnected at the interconnecting apparatus so that design errors which are only evident when the chips are interconnected can be tested for and detected prior to fabrication of the chips.

Abstract: The invention relates to a fastening mechanism (10) for removably securing together two workpieces, such as the mounting plate (50) of a print head housing (16) and the support blocks 12 of a carriage (10) in a line printer. The fastening mechanism has a locking member (22) having a stud portion (24) mounted on the carriage (10) for rotational and axial movement relative thereto and having abutment surfaces (28) cooperating with cam surfaces (56, 62) on the print head housing (16) upon rotation of the locking member (22) so as to latch together the print head housing (16) and carriage (10) by the action of a spring (38) biasing the locking member in an axial direction. The fastening mechanism enables a simple and rapid removal and mounting of the print head housing (16) to the carriage (10) without the use of any tools.

Abstract: A pin feed mechanism (10) for transporting continuous stationery (11) having perforations (46) at both longitudinal edges thereof, in which transport pins (38) are arranged to engage with the perforations (46) and move the stationery (11) past a printing station. The pins (38) each have a tapered end to facilitate insertion of the pins (38) into the perforations (46). The tapered end of each pin (38) is shaped to have biconvex cross section, so that the curvature of its paper engaging surfaces has a constant radius of curvature along the length of the pin (38).

Abstract: A sharpening device for supporting a file for sharpening the cutting elements of a chain saw. The device includes a base portion that is removably secured to the chain bar of the chain saw, and a top guide portion slidably mounted on the base portion and for supporting the file. The top guide portion moves between a first position at the chain for sharpening one of the cutting elements and a second position away from the chain to permit indexing of the chain to locate another cutting element for sharpening. In one embodiment, the base portion includes two sidewalls, and the chain bar is clamped between the sidewalls. In an alternate embodiment, the base portion includes a magnet for holding the base portion to one side of the chain bar, and further includes two flat pins that project from the base portion for resting on the chain bar.

Abstract: A memory system has a plurality of memory modules. A longitudinal parity word is stored in one memory module and correction words are stored in each of the other memory modules. When one of the data words in a memory module having a correction word is changed, the correction word is also changed from a prior value to a new value so that the longitudinal parity of the data in the modules is unaffected. The new value of the correction word is computed by EXCLUSIVE ORing the value of the data word before the change, the data word after the change, and the prior value of the correction word.

Abstract: A data processing system having a plurality of subsystems linked by a star coupler. The star coupler includes contention circuitry for controlling the star coupler so that at any given time no more than one selected subsystem can pass a message through the star coupler. The contention circuitry uses a conventional priority encode circuit to determine the selected one of the subsystems, so that the first message to be received from one of the subsystems is the message passed or, if two or more messages are received from subsystems simultaneously, the message from the subsystem having the highest relative priority established by the priority encode circuit is the message passed. In an embodiment showing an expanded star coupler, the contention circuitry has plural first level contention circuits and a second level contention circuit, each using a conventional priority encode circuit.

Abstract: A memory system having both a primary memory and an alternate memory. The alternate memory stores data to be substituted for data stored at memory locations in the primary memory that have defective cells. The alternate memory includes a byte memory and a bit memory. The byte memory stores bytes of data that are to replace bytes having multiple bit errors in the primary memory. The bit memory stores bits to replace single bits in any byte in the primary memory that has a single bit error. A mapping memory controls access to the primary memory and the alternate memory. The memory devices in the primary memory have either all row defects or all column defects in order to reduce the size of the mapping memory.

Abstract: A data processing system employing broadcast packet switching and having a plurality of subsystems and a system bus for linking the subsystems. The subsystems are grouped within stations that are each enclosed by a computer cabinet. The system bus includes a star coupler, first and second external transmission lines connecting each station to the star coupler, and first and second internal transmission lines within each station that are coupled to the first and second external transmission lines. The subsystems within each station are each coupled to the first and second internal transmission lines by a system bus interface. The system bus interface monitors the system bus for an idle condition, and passes a message from its subsystem to the system bus only when it detects an idle condition on the system bus. Each message on the system bus includes a postamble that is garbled by any system bus interface that detects an error in any message on the system bus.

Abstract: A data recovery system for use in recovering data encoded in a double frequency code on a magnetic disc device includes a data window expander circuit. The data recovery system recovers both separated data and separated clock signals. The separated data signal has a data window which occurs during the second half of each bit cycle of the separated data signal. The data window expander circuit expands the data window, and includes flip-flops for delaying the separated data signal and an OR gate for logically ORing the delayed separated data signal with the undelayed separated data signal. The output of the OR gate is the separated data signal having an expanded data window, which can then be synchronized, with minimal alignment errors, by the separated clock signal.

Abstract: An ink jet printer includes a print head having a plurality of piezoelectric driving elements selectively energizable to cause ejection of droplets of ink through nozzles in a nozzle plate. Ink is supplied to the print head from an ink reservoir which is connected to a bellows device. The ink reservoir and the bellows device together form an air-tight container. The bellows device has a resilient form of construction so as to tend to increase the volume of the container. As a result, an appropriate underpressure is maintained in respect of the ink in the nozzles, such underpressure being necessary to prevent ink escaping from the nozzles under quiescent conditions. In operation, the bellows device progressively collapses so as to reduce the rate at which the underpressure increases as ink is ejected, thereby prolonging the period for which the underpressure is maintained within a desired operating range.

Abstract: A connector for connecting coplanar circuit boards in an edge-to-edge fashion. The connector has a housing with a circuit board receiving cavity extending through and between opposite faces of the housing. The cavity has two opposing side walls which support electrical terminals for contacting conductors on the edges of circuit boards that are inserted into the cavity at the opposing faces of the housing. A passage extends transversely through the housing and intersects the cavity and receives a pin for engaging the terminals and maintaining them fixed within the housing. The edge-to-edge connection of two or more coplanar circuit boards is provided by use of the connector.

Abstract: A bidirectional pulse generator suitable for driving a video disc stylus deflector transducer. A differential amplifier is arranged with both its inverting and non-inverting input terminals connected for receiving a prescribed pulse waveform. First and second diodes are respectively connected between the inverting and non-inverting input terminals and a point of bilevel potential for selectively conditioning one or the other of the diodes to conduct, thereby establishing the quiescent output potential of the amplifier and concurrently shunting the pulsed waveform from one or the other of the amplifier input terminals.

Abstract: An edge connector wherein an insulated base defines an elongated opening and an insulated carrier is slidably mounted to the base. The carrier is provided with an elongated opening for receiving a printed circuit board. A series of conductors are pivotly coupled between the base and the carrier, such that each of the conductors pivots about one end when the carrier is slid with respect to the base. The length of the conductors is sufficient to come into contact with the edge contacts of the printed circuit board when the printed circuit board is received by the carrier and for transmitting a retaining force to the printed circuit board. A series of resilient pins mounted to the base and in contact with the pivot end of respective conductor of the series of conductors provides along with a spring both the retaining force and the contact force necessary for good electrical contact.