Abstract: A cartridge for an inked ribbon has spring support means which maintains a constant back pressure on a uniformly folded ribbon stack inside the storage compartment of the cartridge. The spring support means is displaceable to adjust for dimensional variations occuring within the stack during use.

Abstract: In a high resolution electroerosion printer, a print head comprises a print head body of plastic or glass in which are embedded closely spaced glass tubes. The glass tubes provide low friction passageways for fine wire electrodes which extend through the glass tubes protruding beyond the print head body to be in uninterrupted flexible contact with the metal layer of a record medium. A pair of feed rolls frictionally engage the individual wires such that when the feed rolls are operated they can adjust the position of the wires to compensate for wear of the ends thereof in contact with the metal layer.

Abstract: In a magnetic ink jet printer a continuous stream of ferrofluid ink drops is projected toward a print medium. A magnetic selector located proximate the stream is operated in synchronism with the flight of the ink drops for deflecting individual unwanted ink drops into a drop catcher. Due to fringing effects produced by the selector when unwanted drops are selected, adjacent print drops are deflected a lesser amount from the initial stream trajectory. Print drops not affected by the fringe magnetic field produced to select unwanted drops are subjected to a compensation deflection depending on their position relative to the unwanted drops so that all print drops follow the same trajectory, after passing the magnetic selector in their travel through a vertical deflector and deposition onto the print medium.

Abstract: In a serial printer a movable type character element such as a ball, disc or the like is rotated to present different type characters to the print position. The carrier for the type element is moved along the print line at a predetermined maximum velocity so long as it is possible to move the type element to the next character in time required to move the carrier from one print position to the next. If the type character set-up time is greater, the carrier is run at a slower speed and is then returned to the predetermined velocity for printing.

Abstract: A magnetic deflector for a magnetic ink jet printer has compensating pole pieces which alter the gradient field produced by deflection pole pieces so as to counterbalance centering forces acting on magnetic ink drops moving through the magnetic field in off center locations. The compensating pole pieces are preferably passive and extend from the zero potential region of the magnetic circuit of the deflection pole pieces.

Abstract: A dot matrix printer apparatus has a magnetic ink jet recording head which projects a continuous stream of ferro-fluid ink drops toward a print medium. The ink drops are rastered in the direction orthogonal to the direction of relative motion of the recording head and the print medium to form characters from columns of dots. The slant of the characters caused by the change in direction of relative motion is controlled by reversing the direction or sequence of rastering of ink drops when the direction of printing reverses.

Abstract: In an ink jet printer, drops are generated at a test frequency which is a harmonic of the drop generation rate for printing. If an error in velocity is detected at the test frequency, a coarse correction velocity is made to bring the correct number of drops within the range of one-half the wavelength at the nth drop location relative to a drop detector. Drops are then generated at the printing frequency and a fine correction in the velocity is made if a velocity error is detected.

Abstract: Damper element which absorbs soundwave energy produced in the liquid mass of an ink jet nozzle by a magnetostrictive drop generator is submersed in the liquid mass with or without attachment to the nozzle chamber.

Abstract: A print wheel is rotatably mounted on a carrier driven by a stepper motor to traverse the print line of a document. The wheel contains two or more arrays of characters with preferred characters most commonly used in each array and a number of lesser-used characters divided between the arrays. The print wheel normally makes one revolution for each two or more print positions and if a compare is made in each array the stepper motor advances the carrier at constant speed. Should a compare not be found or the character desired be too close to a previous character for the print hammer to settle out, the stepper motor is stopped for that position until a compare is made in some following array.

Abstract: A serial line printer uses a linear stepper motor of the variable reluctance type in which the toothed stator bar acts as a guide and support for the print mechanism carrier. Sensor elements movable with the carrier sense the presence of the teeth of the stator bar and generate timing signals usable for controlling operation of the printer and the motion of the carrier. The pitch of the teeth in the stator bar is proportional to the spacing of the print locations in a line of print.

Abstract: A servo system for adjusting the velocity of ink drops in a magnetic ink jet printer has a coarse control loop for making coarse increment adjustments to the pump which supplies ink under pressure to a nozzle and a fine control loop for making fine increment adjustments to the pressure of said pump. The velocity of the drops is determined by a pair of drop sensors located one drop wavelength apart at a fixed distance from the drop generation point. The direction of any phase error between pairs of drops is used to generate direction control signals applied to the coarse control loop until a reversal in phase error occurs. A toggle control allows the coarse control loop to make coarse adjustments in pump pressure around a null point velocity before switching direction control signals to the fine control loop.

Abstract: A linear actuator comprises a toothed magnetic motor bar and a motor element having a pair of E-cores on opposite sides of the motor bar. Rollers attached directly to the E-cores ride on the motor bar to maintain a fixed air gap between the motor bar and the pole faces of the E-cores. The E-cores are connected by I-shaped connector plates to hold the tooth relationship between E-cores. The connector plates also are flexible to compensate for variations in thickness of the motor bar.

Abstract: A three phase rotary stepper motor of the variable reluctance type comprises a rotor and an annular stator having three pairs of diametrically opposed stator poles wound with bifilar windings. The stator windings are connected so that opposed poles are energized as a pair having the same polarity. The bifilar winding is connected so that pole pairs are energized with either polarity. A two phase energization scheme is used which causes adjacent poles of two pole pairs to have opposite polarity, while the third pole pair is magnetically neutral. Every three steps of the sequence the magnetically neutral pole pair is magnetized with the reverse polarity.

Abstract: In an ink jet serial printer, a drop collector has horizontal and vertical collector sections or gutters. Unused drops are diverted in the direction of motion during uniform velocity of the ink jet head into the vertical section and into the horizontal section during acceleration/deceleration portions of head motion. A bias potential applied to the vertical drop deflector is removed during acceleration/deceleration to cause unused drops to be directed to the horizontal collector section.

Abstract: A line printer has a print head with plural nozzles arranged in a single row generally transverse to the direction of relative motion of the print head and a print medium. The nozzles are spaced plural dot positions from each other corresponding to a plural dot segment of a single dot matrix character stroke. When the row of nozzles is slanted relative to the direction of motion, drops from the nozzles are used to print stroke segments in plural character strokes simultaneously.

Abstract: In an ink jet recorder, a ferrofluid ink is supplied under pressure to a nozzle to form a continuous ink jet stream. The jet stream is subjected to two or more perturbation forces out-of-phase with each other causing the satellites and drops to fast merge. Plural electromagnetic transducers are located at spaced locations along the stream and energized to produce out-of-phase perturbations on the stream. The spacing of the transducers is differentially related to spacing of varicosities or ink drops produced by first transducer. The out-of-phase perturbations can also be obtained using an electromechanical transducer and electromagnetic transducers located out-of-phase or energized out-of-phase with each other.

Abstract: A digital pulse source generates a frequency analog of a desired velocity to which a d-c motor is accelerated. The acceleration circuit comprises a circuit means for converting a frequency analog signal to a frequency dependent direct voltage and a sawtooth voltage. A comparison circuit generates a motor drive signal having a duty cycle dependent on the relative voltage levels of the direct and sawtooth voltages. The comparative duty cycle of motor drive signal for two different velocities is regulated to be proportional to the square of the ratio of the two velocities.