Abstract: An armature locating and holding structure in which the armature only partially overlaps one of the magnetic poles so as to produce a magnetic tensile force on the armature tending to pull the armature toward the partially overlapped pole and a magnetic gap tending to apply a rotational balance force so as to pull the armature structure toward a pair of stops that limit movement of the armature toward the partially overlapped pole and also limits the rotation of the armature by reason of the magnetic gap.

Abstract: A drive control system for a stepping motor having an optical disk sensor on the rotor shaft. A binary counter counts output pulses from a clock running much faster than the maximum speed expected from the optical disk. Optically-generated pulses, synchronized with the counted pulses, transfer the count from the counter into a storage register and reset the counter. The count achieved by the counter is inversely proportional to the velocity of the rotor shaft. More pulses and a higher count means a lower shaft speed. Therefore, the contents of the register is a coded measure of shaft speed. A code converter is used to determine the power input to the stepping motor to maintain a desired shaft speed. Therefore, the higher the motor speed and the lower the counter output between successive optically generated pulses, the less power is delivered to the stepping motor coils.

Abstract: A conventional stepping motor has an optical disk connected to its rotor. Optically generated pulses from the disk are used to generate a signal indicating the speed of the rotor. A code converter converts the speed signals into a binary-encoded power-required signal for feedback to control the power delivered to the coils of the stepping motor so as to maintain a constant stepping speed. The encoded power-required signal is delivered to a binary comparator which delivers an output pulse of one binary sense or the other. A clock driving a counter generates a binary count having the same number of binary levels as the encoded power-required signal fed to the comparator. The output of the counter is also fed to the comparator. The comparator delivers an output of one binary sense when the clock count is less than the binary-encoded power-required signal and an output of the other binary sense when the counter output is greater than the power-required signal.

Abstract: Paper is carried on an apertured platen and is rotated past a slowly moving printing head so as to scan in a raster fashion from top to bottom and from left to right over the surface of the paper. The paper is held to the platen drum by a vacuum that is applied to the inside of the platen. A valve is located at the entrance of the vacuum system of the platen in order to rapidly dissipate the vacuum so as to release or remove the paper from the still rapidly rotating platen. To facilitate inserting and releasing paper, a shroud system is placed very close to the periphery of the drum and guides the paper during insertion to close proximity with the vacuum. An exit door is provided in the shroud at a convenient location to permit the paper to exit from the drum once the vacuum has been dissipated. The size of the drum is made such that its circumference is slightly less than the length of the paper so as to provide overlap of the top and bottom edges of the paper.

Abstract: A stepping motor is driven with extended pulses producing an effective excitation intermediate to the single phase and the dual phase operations. The unique drive circuit creates a series of drive pulses for each motor phase so that each pulse slightly overlaps the drive pulse of the next adjacent phase. Thus, since each previous phase is still providing torque while the current in the next phase is being built up, the torque characteristics are improved, and the extended pulses are terminated before the subsequent phase is energized so that excessive power consumption is avoided. In closed loop systems, a fixed duration overlap provides the improved speed-torque characteristic at high speeds where the overlap is a large percentage of the drive pulse, while at lower speeds (such as when the motor is accelerating) where power consumption is greatest, the overlap is a smaller percentage of the drive pulse hence minimizing the increase in power consumption.

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: 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: 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 dynamic logic system is disclosed in which a capacitor is charged by a clock signal through a gating device. The capacitor is either discharged or remains at its charged value in response to the impedance of a logic circuit. Two such systems are disclosed in which the output from the first logic system is applied as an input to the second logic system.

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: An AM/FM receiver which demodulates radio signals by computing estimates of spectral parameters of the radio signals. Three spectral parameter estimation circuits are selectively formed from a number of shared circuits according to the type of modulation of the radio signal. In the case of frequency modulated signals, the respective strengths of the desired signal and interfering signals dictate the most favorable circuit configuration. The first estimation circuit calculates the instantaneous amplitude of the radio signal which corresponds to the modulating audio signal of an AM signal, the second estimation circuit calculates the instantaneous frequency of the radio signal which corresponds to the modulating audio signal of an FM signal, and the third estimation circuit calculates the power mean frequency of the radio signal which, when calculated over a short period of time relative to the rate of change of the FM signal, also corresponds to the modulating audio signal.

Abstract: A digital computer arrangement is disclosed including a central processing unit, a plurality of peripheral units coupled to a peripheral bus, a memory access controller, a first memory bus, and a second memory bus. The first memory bus serves a first plurality of memory units and the second memory bus serves a second plurality of memory units. The memory access controller selects which of the peripheral units may use the peripheral bus to access a memory bus during a particular time interval. If use of a particular memory bus is requested by a peripheral unit for an interval in which that memory bus is required by the central processing unit, the memory access controller preempts the usage of that memory bus by the peripheral unit for the interval.

Abstract: A reliable pulse source circuit utilizing two independent but synchronized pulse generators is disclosed. The pulse source circuit maintains output pulses even though one pulse generator fails regardless of the failure mode, i.e., whether the output of the failed generator is stuck high or stuck low. A toggle flip-flop responsive to the presence and absence of pulses from the two generators and its own state outputs controls gating circuitry to generate a sequence of output pulses wherein alternate output pulses occur in response to pulses of one generator and the remaining output pulses occur in response to pulses of the other generator, and if either generator fails, all output pulses occur in response to the pulses of the other generator.

Abstract: A tone detector circuit for detecting the presence of a certain tone or tones in an input signal. An estimate is calculated for each of the following three parameters of the band limited spectrum of the input signal: total power, power mean frequency, and mean square power bandwidth. Each of the three input spectrum parameters is compared to the same parameter of the tone or tones desired to be detected. If a match within certain bounds occurs on all three parameters, the desired signal has been detected.

Abstract: A program controlled data processing system which includes two data manipulation units generally operated in parallel. The two data manipulation units, however, by design react differently in the execution of certain program order words. The system includes a circuit arrangement which compares data generated by the two data manipulation units and generates comparison signals indicating the identity or lack of identity of the compared data. The comparison signals are utilized in the detection of faults and errors and in the determination of conditions as defined by the program.