Abstract: An improved matrix printer is described employing a high order, single track incremental position encoder to provide a plurality of electrical reference signals representative of predetermined print positions along a platen and for locating matrix columns at the predetermined print positions. An electronic circuit is provided for varying the predetermined print positions at which the matrix columns can be located.

Abstract: A capacitive keyboard verification system is disclosed wherein key movement is verified with a high degree of accuracy in a manner largely immune to ambient noise or other electronic or electromagnetic interference. A pulse signal, in the form of a train of pulses, is periodically applied across the capacitor associated with each key. The signal coupled through the capacitor is reconstructed only if it exceeds a predetermined reference level. A test, which depends on the previously verified key state, is made to determine the existing key state. The test for the active key state is conditioned on multiple true comparisons of a reconstructed signal with the originally applied signal throughout the duration of the test. The test for the inactive key state is conditioned on the absence of a reconstructed signal throughout the test. In both instances the newly indicated key state is compared with the state to which the key is assumed to have changed from its previously verified state.

Abstract: An impact printer is described having a control circuit for varying the location at which the printing elements of a printhead are actuated in order to compensate for flight time of the elements and other mechanical characteristics of the printer.

Abstract: The gap between the print head and the printing surface or platen in a printer is extremely critical in certain types of printers. Where printers are required to accept print media of various thickness (single or multipart paper), an adjust mechanism is required to optimize the print gap. A problem arises thereafter whenever ribbon has to be changed or new paper fed into the printer, since the print head must be retracted from its optimum gap position for ease of operation. The present invention provides for automatically resetting the print head to its predetermined previous gap spacing following movement of the print head away from the printing surface for servicing such as paper loading on ribbon replacement. This is accomplished by providing a lever, adapted to move the print head away from the printing surface, with a cam face for mating with a cam follower carried by a gap adjustment arm pivoted for movement in fixed distance increments about a pivot point.

Abstract: A system for tracking an endless image copying or recording belt and maintaining it in alignment within a confined area includes at least three rollers with four rollers being preferred. The first roller is a cylindrical drive roller and the second and third rollers are cylindrical driven rollers. The fourth roller is cylindrical along a major central portion and flares outwardly at the end portions. The third roller is mounted on support arms which, in turn, are mounted to pivot about the axis of the second roller and are biased normally to maintain uniform tension in the belt. If the belt creeps toward one end of the flared roller, the climb to the larger diameter displaces the tape which causes the corresponding end of the third roller to dip thereby causing the belt to move laterally back toward a central position.

Abstract: A drive circuit is responsive to input pulses to supply drive energy pulses to the printing head of a matrix printer so as to produce constant impact forces and constant print intensity over a wide range of print rates by decreasing the energy of the drive pulses as a function of the time interval between successive input pulses as said interval diminishes below a predetermined value. In one embodiment the amplitude of the drive pulses is reduced as the frequency of the input pulses exceeds the predetermined value. In a second embodiment the duration of the drive pulses is reduced as the frequency of the input pulses exceeds the predetermined value.

Abstract: An arrangement for processing data by modifying selected bit portions of coded control signals for comparison with coded input signals to control printing by a printer.

Abstract: A method and apparatus for generating separated data and clock pulse trains from a composite pulse train of interspersed data and clock pulses where a predetermined number of successive clock pulses are absent from predetermined segments of the composite pulse stream. In the preferred exemplary embodiment, the first encountered pulse in the composite pulse stream is passed to a separated clock pulse train. Pulses thereafter occurring during subsequent alternating periodic time intervals are passed to the data pulse stream and to the clock pulse stream, respectively. Absences or non-occurrences of clock pulses in the resultant separated clock pulse stream are detected and counted. After counting a predetermined number of non-occurrences clock pulses in the separated clock pulse stream, the circuit is reset and all of the above recited steps are repeated. An exemplary circuit utilizing a plurality of interconnected monostable multivibrators for accomplishing such data separation is disclosed.

Abstract: Apparatus for automatically searching for a string of ordered characters stored on a magnetic tape wherein the string may be of selectable length employing a dynamic buffer register for storing the candidate strings of characters to be searched and a static/dynamic register for use in identifying the ordered reference string of characters used in performing the search, said candidate characters and reference characters being compared on a bit parallel character serial basis, means are provided to successively delay the relative positions of said reference characters and candidate characters in their respective register stages until a comparison indicates that the string of characters identified in the reference register have been located in the candidate register.

Abstract: A regulator for a two phase shaft encoder used in sensing irregular body movements which determines when the light transmission of a photocoupler is maximum and corrects the photocoupler output to agree with a reference value.

Abstract: A communication receiver for receiving speech and sequential control tones wherein a pulser circuit is provided and rendered operative in a predetermined manner to produce a pulse pattern for intermittently rendering the receiver operative. The receiver comprises a tunable filter for selecting the desired control tones and detector circuits for detecting said control tones to provide a plurality of control signals. Said control signals are employed to control the pulser circuit to render the receiver operative to receive speech and control tones in a predetermined manner. The tunable circuit is responsive to said detected control tones for having its tuning changed to sequentially receive said control tones.

Abstract: An arrangement for controlling the speed of payoff and winding reels and an associated capstan drive in a recording and reproducing arrangement during start up, running and stopping operations employing the application of control signals to the capstan and reel motors which include novel, combined use of capstan motor armature counter-electromotive force, reference signals and capstan motor terminal voltage.

Abstract: Print control apparatus which combines a first in - first out memory for storing received data with a random access memory for feeding data to a movable type printer to eliminate the need for suspension of receiving input characters or the adding of fill characters or time delays during the period when printer action is suspended during execution of control actions, such as paper feed. The apparatus controls the transfer of data from the first in - first out memory to the random access memory by keeping the latter memory continuously replenished with data as the printer executes its printing action and printed characters are erased from the random access memory.

Abstract: This invention relates to an improved design of removable type carrying fingers used in belt printer applications wherein a shoulder is provided on the fingers to fix the fingers with respect to the edge surface of the belt and the shoulder is located where the concentration of stresses developed at the shoulder during printing are compressive and not tensile.

Abstract: Data transfer and control apparatus for coupling between a data source having a first character per second rate of delivery of coded pulse groups each representing a character and a recorder for recording data in blocks of a fixed number of characters at a second character per second rate comprising an incremented data storage register; an incremented tag signal storage register; means for applying coded pulse groups to said register from said source; means for providing tag signals, associated with respective applied coded pulse groups, to said tag signal register; means for incrementing said applied pulse groups and associated tag signals synchronously in their respective registers at a third character per second rate.

Abstract: An arrangement for detecting a change in the number of printing characters associated with a set of such characters employed in a printer and for automatically modifying the print control algorithm employed in the printing process in accordance with said detected change.

Abstract: An arrangement for protecting hammer drive solenoids in a printer against failure in associated SCR circuits by correlating the currents of SCR gate firing pulses with subsequent SCR conduction.

Abstract: Achieving N-key rollover by detecting the leading edge of the binary coded signal generated in bit parallel form in response to keyboard key depression and blocking the receipt of data representing a subsequently depressed key where the width of each binary bit signal is less than the interval between two successive system timing pulses which in turn is much less than the 10 millisecond or so interval between successive key operations by an operator as a result of rollover typing.

Abstract: In a dot matrix printing head having a plurality of printing elements or styli each driven by an associated electromagnetically operated hinged armature, an adjustable spring arrangement for adjusting the preload biasing of each armature against an armature stop to insure that the associated electromagnets are matched with respect to flight time and can be set to deliver the proper printing force to each styli.