Abstract: An improved dot matrix actuator is provided which includes a magnetic circuit formed of a yoke assembly and a pivotal armature. The armature is pivotally supported with respect to the yoke by means of a flexure assembly which eliminates the need for a true pivot between the two elements. The elements are shaped so as to maintain a constant small air gap therebetween so as to maximize the magnetic efficiency of the device while eliminating wear. The device is operated just below saturation of the magnetic circuit in order to maximize efficiency. In addition, the actuator includes several features for maximizing its speed and operational efficiency.

Abstract: A motor control system for a high accuracy incremental motion system such as a paper feed system in a high speed printer. The system utilizes a stepping motor which is driven in one of two modes, depending upon its position. During most of the movement from one position to another, the motor is driven as a DC brushless motor. This is accomplished by commutating the phases of the motor so that they are energized around the peaks of their torque curves. The motor is driven in a closed loop fashion, with velocity commands being generated by a velocity profile generator incorporating a microprocessor. Both position and velocity feedback are utilized. Since the motor is driven as a DC brushless motor, traditional control theory methods (e.g., Root locus, Bode, etc.) can be employed.As the motor nears the final desired position, the system switches so that the motor is energized as a step motor.

Abstract: An improved dot matrix actuator is provided which includes a magnetic circuit formed of a yoke assembly and a pivotal armature. The armature is pivotally supported with respect to the yoke by means of a flexure assembly which eliminates the need for a true pivot between the two elements. The elements are shaped so as to maintain a constant small air gap therebetween so as to maximize the magnetic efficiency of the device while eliminating wear. The device is operated just below saturation of the magnetic circuit in order to maximize efficiency. In addition, the actuator includes several features for maximizing its speed and operational efficiency.

Abstract: A cordless communications system wherein transmission is made and received via magnetic lines of induction comprises a base station and at least one mobile station wherein the base station receives and transmits voice or data signals at different frequencies. The base station employs at least two magnetic loop antennas for transmission and reception, respectively, oriented so as to provide a toroidal magnetic field which allows 360 degree transmission and reception in the planes of the antennas. The components of the at least one mobile station are mounted in an article of clothing. The mobile station is arranged in the article of clothing in such a manner as to insure a substantially constant effective coupling area with the base station antenna.

Abstract: A device for horizontally positioning and maintaining the horizontal tension on paper forms as they are transported through a printer. The device employs a single control knob to make all position adjustments to the paper tractors which grip the computer forms. The device utilizes a cable pulley system to position the paper tractors. The control knob has a first position in which adjustment of the tension on the paper form is facilitated and a second position which facilitates adjustment of the position of the paper form within the printer.

Abstract: An improved pulley system for use with band printers or the like. A steel printing band is looped around a pair of capstans covered by sleeves made of elastomeric material. The sleeves include a plurality of downwardly angled flexible circumferential flanges and a lower horizontal rim. The band contacts the flanges and as the capstans rotate, inward force on the band is transferred to a downward force by means of the flanges. The downward force causes the band to move into contact with the lower horizontal rim, thereby vertically aligning the band in the printer. In an alternate embodiment, a plurality of non-flexible circumferential ridges are included. The central ridges extend farther out from the surface of the sleeve and serve to define a crown. The sleeve configuration serves to reduce wear and accurately align the printing band within the printer assembly.

Abstract: An actuator assembly for a dot matrix printer of the stored energy type in which a plurality of flexible spring hammer elements are mounted in an interleaved arrangement in order to provide a compact structure. The actuator assembly includes a mounting block having upper and lower magnetic circuits and spring hammers attached to it. A portion of the magnetic circuits is coupled to the rear of the mounting block in order to facilitate heat dissipation from the actuator. The pole pieces of the magnetic circuits are positioned to reduce resonance of the spring hammers to thereby decrease cycling time. Permanent magnets utilized in the assembly are arranged in a non-symmetrical fashion in order to increase the magnetic efficiency of the device. Integrally connected pole pieces and permanent magnets are used in the assembly to reduce manufacturing costs without degrading performance.

Abstract: The impact pins of a matrix printhead are brazed by a laser to a print hammer of the flat spring type. The print hammers are then attached to a printhead mounting block adjacent to each other with the impact pins in substantially a straight line. The attached print hammers are then shaped by an electric discharge machining (EDM) process by a single electrode to simultaneously machine the impact pins to the desired shape and to position the tips of the impact pins at a precise distance with respect to one another.

Abstract: A hammer bank assembly for use in line printers. The assembly includes an extruded metal rear frame having a uniform thickness and a plurality of machined mounting surfaces which are machined in accurate relationship with respect to one another. A pair of extruded plastic shoes are mounted to the top and bottom of the frame and also include machined surfaces for accurately aligning them with respect to the frame. The shoes include a plurality of mounting slots which are cut by means of a gang cutter. The slots serve to accurately align a plurality of print hammers in the shoes. The hammers are insulated with respect to the frame and the shoes in order to prevent sliding motion and subsequent wearing of the print hammers. Also disclosed are several methods of simplifying the construction procedure of the hammer bank assembly.

Abstract: A closed loop control system for a stepper motor provides the necessary feedback to accurately control the position of a motor during acceleration, constant velocity and deceleration. Generation of commutation signals is based upon a monitoring of motor position to determine the points where commutation would result in maximum accelerating torque during acceleration and constant velocity and minimum braking torque during deceleration. These points indicate the earliest points at which commutation may occur. Commutation may be delayed in order to reduce the accelerating torque during acceleration and constant velocity or increase the braking torque during deceleration.

Abstract: A multi-colored dye-based printing ribbon is disclosed which has a thermoplastic resinous barrier preventing the colored portions of the ribbon from interfusing.

Abstract: A digitizer for receiving sine and cosine encoder signals and providing a digital output representative of the phase angle of the encoder. A counter is used to generate a variable reference angle, and memories are used to generate digital signals representing the sine and cosine of the output of the counter. These signals are multiplied by the analog cosine and sine inputs, respectively, in order to determine the direction of the difference between the encoder phase angle and the counter angle. The counter is incremented or decremented so as to make the digital angle output provided by the counter equal to the phase angle of the encoder. A velocity indication may be provided by the addition of a low pass filter to the circuit.

Abstract: A capacitive encoder utilizing a stationary plate having transmitter elements and receiver elements located on the surface thereof and a moving plate having two conductive areas separated by a sine wave shaped gap. The receiver elements on the stationary plate overlie the gap and provide outputs which vary as a function of the position of the gap with respect to the output elements. Signals from the output elements are differentially amplified and demodulated in order to provide precise sine and cosine outputs, the accuracy of which are unaffected by variations in the input signal.

Abstract: A compact band printer system incorporating an inverted character band and a hammer bank assembly in which the hammer bank frame serves as the main support frame for the printer. Ribbon, band pulley and tractor drive assemblies are all supported by the hammer bank frame. A platen is secured to the frame and serves to increase the rigidity of the structure.

Abstract: An improved multicolor ribbon cassette system for use with a printing mechanism. A ribbon cassette is carried on a plate which is pivotally connected to a shuttle mechanism. The plate rotates about an axis which is perpendicular to a printing medium and the portion of the ribbon adjacent the printing mechanism. The pivot plate is tilted up or down to position a different part of the ribbon in alignment with a printing mechanism. The configuration of the device is such that the ribbon will remain parallel to the printing medium as it is tilted. The position of the pivot plate is controlled by means of a barrel cam driven by a stepper motor. The stepper motor is controlled by a logic circuit. An optical sensor is also connected to the logic circuit to determine whether a single color or multicolor cassette is in position.

Abstract: Disclosed is a unique wire coil having flat sides and a maximum packing density. The coil is wound in a hex fashion (i.e., with each interior turn of the coil being in contact with six other turns of the coil) and has a plurality of turns and a plurality of layers of turns. The coil is wound generally perpendicular to a central axis, and each layer of turns is wound at an angle of approximately 30 degrees with respect to the axis, which results in a coil having flat sides.

Abstract: There is disclosed a hammer assembly for a high speed impact printer of the type comprising a solenoid including a coil and an axially-apertured pole piece, the pole piece having a conically-shaped recessed surface, an axially movable armature within the solenoid, the armature having a tapered conical leading surface facing and substantially parallel to the recessed surface of the pole piece, and a hammer, one end of the hammer being rigidly connected to the armature to form a unitized armature/hammer element for striking a print element in the printer, the hammer extending through the aperture in the pole piece. The present hammer assembly achieves, when compared to previous designs, a longer stroke, an increase in impact energy, a reduction of rebound and settling time, an increase in hammer life expectancy, a decrease in cost, improved reliability and a reduction in weight.

Abstract: An improved print hammer incorporating crossed-spring support wires having a round cross section so as to render the hammer relatively flexible in a direction lateral to hammer travel during printing. The spring wires are connected between a lower body portion and a foot section. The lower body portion and foot section are designed so that the spring wires enter them substantially perpendicularly, thereby reducing stress. The foot section incorporates a pair of mounting pegs which serve to accurately locate the hammers in a hammer bank assembly. A pair of weights can be included on the spring wires in order to dampen recoil motion which occurs after the hammer impacts against a print character. The crossing point of the spring is positioned so that the springs are flexed by a constant bending moment, thereby reducing stress on the springs.

Abstract: A process for making an elastomer for use in printing/drive belts is disclosed wherein a mixture of approximately 2 equivalents of toluene diisocyanate consisting of about 88 wt. % of the 2,4 isomer and 12 wt. % of the 2,6 isomer is reacted with a polyether or polyester having difunctional primary hydroxyl groups to form a prepolymer. The prepolymer is then reacted with a diamine curing agent to form the elastomer.

Abstract: A hammer bank assembly for use in line printers. The assembly includes an extruded metal rear frame having a uniform thickness and a plurality of machined mounting surfaces which are machined in accurate relationship with respect to one another. A pair of extruded plastic shoes are mounted to the top and bottom of the frame and also include machined surfaces for accurately aligning them with respect to the frame. The shoes include a plurality of mounting slots which are cut by means of a gang cutter. The slots serve to accurately align a plurality of print hammers in the shoes. The hammers are insulated with respect to the frame and the shoes in order to prevent sliding motion and subsequent wearing of the print hammers. Also disclosed are several methods of simplifying the construction procedure of the hammer bank assembly.