Abstract: An integrated circuit Read-Only Memory (ROM) with improved speed of operation is disclosed as generally representative of similarly improved logic arrays. The ROM includes parallel rows of conductors oriented normal to parallel doped regions which form column conductors. The ROM is implemented with field-effect transistors and comprises two decoder fields and a data field. The transistors of the decoder fields serve to define open circuits between adjacent column conductors in accordance with binary input signals applied to the decoder fields. In the illustrative ROM, a first column conductor is connected to a return terminal of a power supply and a second column conductor is connected to a "pull-up" circuit. The illustrative circuit provides for the connection of power supply return connections to both ends of the one column conductor and provides for the connection of pull-up circuits to both ends of the second column conductor.

Abstract: In a cartridge for an endless typewriter ribbon, a fresh ribbon is stored in the cartridge with a substantial length of ribbon wound in a convolute around a roller. When the cartridge is mounted in a printing apparatus, the ribbon is drawn from the cartridge, exhausting the convolute. When the cartridge is fully mounted in position in the printer, a single path of ribbon extends into the cartridge and through an opening along a chord of the roller and out from the cartridge. A brake is provided to limit motion of the roller so as to preclude premature unwinding of the convolute and to limit oscillation of the roller during operation of the printer. With the normal operating path of the ribbon extending through the chord-oriented slot of the roller, ribbon can readily be rewound onto the roller upon removal of the cartridge from the printer.

Abstract: A re-entrant shift register comprising eight levels and in the illustrative embodiment eight stages per level, is selectively used in the buffering of information between an asynchronous signal source, e.g., a manual keyboard and a data sink, e.g., a controller which accepts information upon an asynchronous basis. Information to be transmitted from a data source to the data sink is entered in parallel in a register in the form of a latch under control of write control circuitry. Similarly, data to be transmitted to the asynchronous data sink is temporarily stored in a parallel output register in the form of a latch. The writing of information into and out of the output latch is under the control of read control circuitry. The write control circuit includes a write counter and the read control circuit includes a read counter.

Abstract: A variable reluctance motor wound for two-phase excitation is excited with single phase pulses, whereby the de-energization of one phase coil aids in the energization of the succeeding (and preceding) phase coil, in which a phase coil that is about to be de-energized is energized for a short period with maximum excitation energy power in order that the decay from that maximum power level, upon advance of the stepping motor, induces, by transformer action, an aiding voltage in the next succeeding phase coil so as to increase the speed of excitation of that next succeeding phase coil.

Abstract: In order to advance an inked ribbon in a printing apparatus in which a printing carriage mechanism moves across the width of a platen, one-way brakes are placed on ribbon guide rollers on the printing carriage mechanism to permit relative movement between the printing carriage mechanism and the inked ribbon as the printing carriage mechanism is advancing from left-to-right across the paper. One-way brakes are placed on return rollers in the ribbon path in order to prevent the inked ribbon from moving with respect to the platen as the printing carriage mechanism is moving from left-to-right across the paper. When the printing carriage mechanism moves from right-to-left in order to return to the left-hand margin, the one-way brakes on the ribbon guide rollers on the printing carriage mechanism apply substantial friction to the inked ribbon and drag the inked ribbon with the printing carriage mechanism as the printing carriage mechanism returns from right-to-left.

Abstract: A paper web is maintained on a rotating apertured drum by means of a vacuum created inside of the drum. The paper length is slightly greater than the circumference of the drum thereby providing a tangentially projecting flap which is detected by a flap sensor. The concurrance of a pulse from the flap sensor with an end of message signal enables a counter. A first series of selected states of the counter are decoded and used to interrupt the vacuum causing the paper to come to rest against a shroud surrounding the drum. A second series of counter states, some of which coincide with the first series, open a discharge door covering a paper discharge opening in the shroud. When the vacuum is reapplied to the drum, upon expiration of the first series of counter states, the rotating drum boosts the paper out through the discharge opening.

Abstract: A circuit is described for selectively increasing the number of text rows on the display screen of a CRT. The number of scan lines in each text row is reduced by one in response to a display format selection signal. The scan lines so saved are utilized to form two additional text rows. A variable modulus scan line counter is used in combination with a decoder to provide the scan line counter modulus desired. Additionally, a text row counter is used in combination with a second decoder to selectively change the modulus of the text row counter to correspond with the selected modulus of the scan line counter. A compressed display is provided by simultaneously changing the modulus of both the scan line and text row counters.

Abstract: A printing apparatus having a moving carriage with a snap action switch mounted thereon to initialize the left and right margins of the printing apparatus. The carriage is moved to the left until the snap action switch strikes a stop on the frame of the machine. The carriage is then moved a predetermined distance to the right, and a left margin counter is set to zero while a right margin counter is set to a count representative of the width of printing between margins. The counters are incremented and decremented by movement of the carriage with the zero point of each counter representing presence of the carriage at that associated margin. Manual devices are provided for setting a narrower printing field with wider margins at either side by resetting the margin counters. Also, a margin release allows movement of the carriage outside of the narrowed printing field but never outside of a maximum printing field.

Abstract: A supply spindle for a cassette recorder which includes means for reducing the abrupt start-up forces to which the recording tape within the cassette is subjected by incrementally coupling the inertial mass of the supply spindle to the tape upon start-up. The supply spindle includes a shaft carrying a supply head for engaging a cassette spool. The supply head is axially as well as rotationally movable upon the shaft. A coil spring, fixed to the shaft and supply head, urges the head to the end of the shaft. Additionally, the spring rotatably biases the supply head against a stop carried on the shaft. Initially upon start-up, only a portion of the mass of the supply spindle is coupled to the magnetic tape with the full mass being subsequently coupled thereto.

Abstract: A circuit is described for controlling a programmable logic array adapted for use with a communications terminal. The logic array includes an input AND-section defined by a plurality of addressable fields and an output OR-section. One field of the input section is addressed by an incoming address register selectively loaded with incoming data. A second field is addressed by a branch address register loaded with selective outputs of the output section thus providing program branching capabilities. Also, a loop counter and a clocked program counter address two additional fields of the input section. The loop counter facilitates program looping in the logic array while the program counter affords real time operational characteristics for the control circuit.

Abstract: A stepping motor is described having two operative modes, the first mode being a normal rotary mode and the second a stationary mode. During rotary operation, the induced energy created by interruption of the current flow through the energized phase winding is dissipated quickly by a zener diode connected across the winding. In the stationary mode, a pulsed current is fed to one of the phase windings of the motor to assure stationary positioning of the rotor. During stationary operation, the zener diode is shunted with a second conventional diode providing a low impedance path to the current induced in the phase winding upon de-energization. This low impedance path greatly reduces the energy dissipated during the off condition of the pulsed current thereby greatly reducing motor power requirements during stationary operation.

Abstract: Unidirectional driving torque is applied to the inputs of first and second differential gears. Each differential gear includes an output blocking gear as well as a spool output gear coupled to a spool with a ribbon web transported between the spools. A locking gear alternately engages the blocking gears and is held in position by a detent mechanism which yieldably restrains rotation of the locking gear. Each of the spool output gears are provided with unidirectional brakes. The restrained blocking gear selects the differential gear through which the input drive is transferred to its respective spool. A web tension condition causes the restrained blocking gear to rotate the locking gear against the detent and the locking gear increments to its alternate position with the previous supply spool becoming the take-up spool.

Abstract: A circuit for cancelling nontonal variations in the output signal from a facsimile scanner. The circuit generates a location signal which corresponds to the physical location of the document sample. The location signal is passed through a function generator, inverted and thereafter multiplied with the output signal of the scanner. Since the characteristic of the inverted function generator output is the reciprocal of the nontonal characteristics of the scanner signal, the resulting output signal from the multiplier is substantially free of nontonal variations.

Abstract: The illustrated printer effectively divides the surface of a paper into a large number of small areas termed dot locations each of which may or may not receive one or more ink drops depending upon the tonal level to be printed. Fifteen tonal shades are utilized with the tonal scale evenly divided by averaging the number of drops over a given number of dot locations to effectively generate fractional drop intensities. Selected ink drops generated by an ink jet are charged as determined by an incoming signal and the charged droplets directed at selected dot locations on the paper. The charge duration is not related to the frequency of the ink drop generation and further, the time of initiation of the drop charging period and the ink drop frequency are asynchronous. Thus, for a given charging period, a varying number of ink drops will be charged resulting in an averaging of the ink drops over several dot locations corresponding to a single tonal value.

Abstract: A print hammer bumper for an on-the-fly impact printer which includes a hammer mechanism having a plurality of print hammers disposed in a linear array. The bumper serves to automatically adjust the forward force of the hammer to the number of paper plys being printed and to dampen the rebound energy of the hammer return stroke. The bumper is in the form of an elongated material having two portions each exhibiting different characteristics. A first portion of the bumper, which is positioned to engage each of the print hammers during their forward printing stroke, exhibits a hardness characteristic such that it readily compresses to adjust the printing force to the number of paper plys being printed. A second portion of the bumper exhibits a low resiliency characteristic and is positioned to engage the hammers upon their return or rebound stroke so as to absorb the hammer rebound energy, thus preventing character overprint by a rebounding hammer again striking the paper.

Abstract: A D.C. to D.C. converter including a start circuit having a choke with a primary winding and a start winding. A portion of the input power is fed through a section of the start winding to the base of a switching transistor connected in series with the primary winding. The transistor is operated as a blocking oscillator by the start circuit and a voltage is induced across a secondary winding of the choke. The secondary voltage is rectified and fed to the control input of a pulse width modulator. In response to a predetermined level of the secondary voltage, the output of the pulse width modulator is coupled to the base of the transistor and the start circuit disabled. Current overload and transient voltage protection circuits are also included.

Abstract: A facsimile transmission system is described which includes a transmitter section having an optical sensor driven across a selected document by a variable speed motor controlled by the frequency of an oscillator. The relative movement of the sensor with respect to the document is indicated by a pulse generator which clocks the output of the sensor into a storage memory. The stored data is clocked from the storage memory by the oscillator output and fed, along with the oscillator signal, to a diphase modulator. At a receiver section, the diphase signal is demodulated providing data and clock signals. The data signal is placed into a receiver storage memory. The clock frequency is used to control the speed of a recorder motor driving a recorder. A pulse generator is coupled to the recording device and generates recorder location pulses which are used to clock the data from the memory.

Abstract: A circuit for controlling a graphic display printer wherein a paper sheet is wrapped about a rotating drum and maintained in place thereon by a vacuum. The length of the paper sheet is slightly longer than the circumference of the drum and thus defines a tangentially projecting flap. A sensor detects passage of the flap and in response to the initial detection, a counter is started having a cycle corresponding to one rotation of the drum. Selected states of the counter are digitally compared to the output of the flap sensor. After the rotational position of the flap has been determined twice for each of three successive drum revolutions, a paper validation signal is generated indicating that the paper is properly wrapped about and rotating with the drum. In response to the validation signal, printing is started.

Abstract: A selector disc defining a single revolution spiral aperture is concentrically rotated with a scanning disc defining four nested multiturn spiral apertures. An elongated fixed slit is positioned between the discs and as the discs rotate, an exposure aperture is defined by the slit and a selected scanning spiral, the aperture moving linearly across the slit. The drive ratio between the discs is such that their relative positions advance so that adjacent scan lines are defined by alternate scanning spirals. Further, each scanning spiral is composed of a series of contiguous, arcuate segments forming in the general path of an Archemedian spiral thus providing a scanning system having improved resolutional characteristics.

Abstract: An asynchronous data input signal is detected and synchronized by a fast-acting circuit. The input is used to modulate a local clock and a detecting latch is then driven by the data-modulated clock. Most of the propagation delay found in conventional detector-synchronizers is eliminated since the SET input to the latch, which is essentially the clock signal, is generated without any gate delay and the CLEAR input is generated with only a single gate delay. Thus, the circuit is well suited for multiple clock systems in which detection and synchronization to one clock must be accomplished before the pulse of a second clock begins.