Abstract: A dot matrix printer having a plurality of hammers on a hammerbank with a counterbalance for the hammerbank in adjacent parallel relationship to the hammerbank. The hammerbank and counterbalance are driven by a first crank arm connected to the hammerbank and a second crank arm connected to the counterbalance with looped circular portions having bearing surfaces for moving the crank arms in opposite relationship to each other. A single shaft with two eccentrics, each respectively in the bearing surfaces turns the two crank arms. The crank arms are in close parallel relationship to each other and close proximity to the hammerbank and counterbalance. The single shaft is connected to a motor for driving the hammerbank and counterbalance, and is formed with a stator having coils with a magnetic ring formed as a rotor portion surrounding the stator, and a flywheel surrounding and connected to the magnetic rotor ring.

Abstract: A data converting apparatus and process for converting outline representations of a character into its bit mapped form using two buffers one being for the bit mapped form of the character symbol and the other for the chain-code representation of the outline of the character are disclosed. Three steps are utilized in the process. The first step draws the character outline on to the drawing buffer and generates the chain-code representation with flags to indicate contour collisions. The contours are then scanned one more time to add missing flags on the chain-code representation. Finally, the inside part of the contour on the drawing buffer is filled using the chain-code representations of the contour, to provide a filled character.

Abstract: A printer is disclosed of the dot matrix type having a series of hammers with pins that print upon an underlying media, and which are released from magnetic retention by reversing the polarity of a permanent magnet and having electro-mechanical drive circuits and logic circuits. A power supply supplies an output of a voltage level for driving the electro-mechanical circuits connected to a ribbon drive, platen drive, paper feed, shuttle motor, and fans at a given voltage and the hammers at a different voltage. A thermal sensor is connected to a heat sink of the power supply, and to the printer controller to change the rate of printing when pre-established temperatures are sensed.

Abstract: This specification discloses apparatus and a process for printing data on a web of print from data related to a wider web than that to be printed upon. It includes a printer having a paper output of a narrower web than data from the wider web, and the provision of data as to the narrow and wide web width. The apparatus and process establishes the difference between the narrow web width of the printer and the wide web width and calculates the number of pages of narrow web width to be printed thereafter forming a raster output from the difference between the narrow web width and the wide web width to establish the width for printing by the printer.

Abstract: This disclosure sets forth a dot matrix printer having an improved ribbon drive. The ribbon drive is provided by two respective stepper motors. When one stepper motor is in a take-up mode, the second is in a feed mode. The process is reversed proximate the end of the tape as it is unwound. A re-generative mode for the feed motor is provided and a resistance bank varies amounts of drag on the ribbon as it is fed from the feed motor spool. Both motors when in the take-up mode are driven by full H bridge drivers and amplifiers controlled by a micro controller through an address and decode input and output latch. In order to provide for a uniform velocity of the print ribbon the angular velocity of the take up motor is controlled by counting the zero crossings of the feed motor, and then loading it into the micro controller to compare it with a look-up table for purposes of providing a proper speed to the take-up motor and the proper peak drag through the resistance bank to the feed motor.

Abstract: A process and apparatus for welding a tungsten carbide printing tip of a dot matrix printer to a hammerspring by holding the hammerspring in a fixture with a first electrode in adjacent relationship thereto and a second electrode in adjacent relationship to a tungsten carbide printing tip having cobalt and forcing said tungsten carbide printing tip into adjacent relationship with said hammerspring while causing cobalt in said tungsten carbide printing tip to be welded to said hammerspring through a welding current between said first and second electrodes.

Abstract: Each of a pair of spaced apart paper feed mechanisms within the paper feed system of a dot matrix line printer has opposite upper and lower portions thereof slightly angled relative to each other and disposed on opposite sides of and close to an elongated print station having a platen at one side thereof on which the paper feed mechanisms are mounted. Guides within the print station direct a length of paper introduced onto one portion of the paper feed mechanism through the print station and onto the other portion. Each paper feed mechanism is locked in a desired position on the platen using a manually operated lever arm arrangement having a mechanical advantage. Phasing or pitch adjustment between the opposite portions of each paper feed mechanism is accomplished by either of two arrangements which vary the position of a pulley engaging an endless belt between the opposite portions in combination with an opposite spring mounted pulley which bears against the inside of and tensions the endless belt.

Abstract: The specification describes a low reluctance magnetic circuit for a dot matrix line printer for retaining hammersprings by the magnetic circuit having pairs of pole pieces formed of magnetically conductive sheets having a space for receipt of a permanent magnet. A coil is wrapped around a portion of each of the pole pieces between the magnet and the ends to provide a reverse magnetic field to the magnetic field provided by the permanent magnet. A magnetic shunt is established between the pole pieces to provide a greater magnetic effect. The pole pieces are sized and plated at the ends, with a spaced wear bar between them to provide improved performance and longer wear.

Abstract: The specification sets forth a hammerspring for a dot matrix printer having a plurality of such hammersprings spaced along a hammerbank with permanent magnetics to draw said hammersprings into a retracted and uniformly stressed mode through a spring portion which are released by overcoming the magnetic retention, the hammerspring formed with a base portion connected to the hammerbank with a spring portion extending from said base portion having a decreasing transverse cross sectional area extending to an enlarged end portion for improved magnetic retention against said permanent magnets.

Abstract: An improved hammerbank in a dot matrix line printer has two different sets of staggered apertures therein along the length thereof for drawing pressurized air at the outside of the hammerbank therein to provide turbulent, high velocity cooling air in the region below the magnetic coils of the magnetic hammer actuators. The cooling air is confined to passage over the magnetic coils by enlarged flanges on the coil bobbins which form an air dam. The air dam discourages escape of the cooling air through spaces between the hammer springs.Magnetic interaction between adjacent magnetic hammer actuators is minimized due to the absence of common magnetic materials extending therebetween, except for the permanent magnets which hold the hammer springs in the retracted position. The permanent magnets are common to a plurality of the magnetic hammer actuators and by physically extending therebetween serve to prevent substantial leakage flux from occurring.

Abstract: In a printer in which a shuttle is driven in reciprocating fashion by a rotating cam, a counterbalance assembly disposed on the opposite side of the cam from the shuttle and having a cam follower disposed along a common axis extending through the cam and a cam follower of the shuttle includes a mass in the form of a generally rectangular block mounting the cam follower at one of a pair of opposite ends thereof. Reciprocating movement of the block in response to rotation of the cam is provided by a pair of tapered flex pivots coupled to opposite ends of a base and extending upwardly and coupled to the opposite ends of the block. The end of the block opposite the cam follower receives a spring disposed against a reference surface to bias the cam follower against the cam.

Abstract: A printer tractor drive assembly is specified having a belt with pins which engage paper which is to be moved across a print station. The assembly includes a split lid covering the paper being driven. One portion of the split lid can be opened to expose and remove the paper along its perforations, while the other portion of the split lid retains the paper on the tractor pins.

Abstract: A dot matrix line printer is disclosed in which the amount of wear of an ink ribbon is measured by continuously compiling data representing impacting action of the printer as the printer prints.In one embodiment, this is accomplished by initially determining a dot count based on the length of the ribbon and representing the maximum theoretical useful life of the ink ribbon and then decreasing the initial dot count as printing thereafter commences. The dot count remaining is continuously divided by the initial dot count to determine the percentage of ribbon life remaining. When the dot count has been increased substantially to zero, a worn ribbon indication is provided to initiate an audible or visible alarm and to prevent further printing until the worn ribbon is replaced. As printing occurs the dots actually printed are counted, and this count is applied to reduce the initial dot count at a rate determined by the type of printing being undertaken.

Abstract: A dot matrix line printer is disclosed in which the amount of wear of an ink ribbon is measured by continuously compiling data representing impacting action of the printer as the printer prints.In a first embodiment, this is accomplished by initially determining a dot count based on the length of the ribbon and representing the maximum theoretical useful life of the ink ribbon and then decreasing the initial dot count as printing thereafter commences. The dot count remaining is continuously divided by the initial dot count to determine the percentage of ribbon life remaining. When the dot count has been decreased substantially to zero, a worn ribbon indication is provided to initiate an audible or visible alarm and to prevent further printing until the worn ribbon is replaced. As printing occurs the dots actually printed are counted, and this count is applied to reduce the initial dot count at a rate determined by the type of printing being undertaken.

Abstract: In a printer in which a plurality of hammers mounted along the length of an elongated hammerbank are selectively fired as the hammerbank is reciprocated relative to an elongated platen to impact a length of ink ribbon against at least one length of print paper supported by the platen to effect printing in dot matrix fashion, the platen being rotatable about an axis of rotation to vary the size of a platen gap between the plurality of hammers and the platen, a mechanism is provided for positively locking the platen in any one of a succession of different rotational positions to provide locking platen gap adjustment. The Positions are identified in order to facilitate resetting of the platen to a desired gap size. The mechanism includes a rotatable knurled thumbknob having mounted thereon a cam having a succession of eccentric or radially varying detents in an outer surface thereof which receives the end of a pivotally mounted, spring-biased lever.

Abstract: In a printer in which drive transistors coupled to hammer drive coils control energization of the coils within each of a plurality of magnetic print hammer actuators to provide firing of hammer springs associated with the print hammer actuators, leakage of one or more of the drive transistors when they are switched off is detected by a testing circuit which flags a fault condition to turn off the driver circuits if the current at a junction common to all of the drive transistors exceeds a predetermined threshold value. This provides an early warning system in which faulty transistors are routinely detected well before they have a chance to fail and thereafter burn out the associated coil included within a hammerbank of the printer.

Abstract: In a printer in which an elongated shuttle is driven in reciprocating fashion across a print paper with hammers mounted along the length of the shuttle being selectively fired to print dots on the paper, a timing system provides hammer fire pulses denoting the positions of the shuttle at which hammer firing should be initiated to print in the proper dot positions. Proper timing is maintained so as to allow for printing during acceleration and deceleration as well as during constant velocity movement of the shuttle by determining the average shuttle velocity between each successive pair of fence post pulses generated by a shuttle-coupled encoder. The average velocities are represented by the time lapses between occurrence of the pairs of fence post pulses which are measured and stored during each startup of the printer as well as each time the nominal operating shuttle velocity is changed as part of a change in printer operation.

Abstract: In a dot matrix line printer in which a plurality of hammer springs mounted along the length of an elongated reciprocating hammerbank are selectively released or fired to impact dot printing impact tips mounted thereon against a print paper through a length of ink ribbon to print dots, the wear that would otherwise occur each time one of the hammer springs rebounds back into contact with a pair of pole pieces against which the hammer spring resides when in its retracted position is greatly minimized by chromium masses plated on the tip of the hammer spring and on the tips of the pole pieces. Chromium platings on each hammer spring are confined to the end of the spring and comprise either a pair of masses adjacent the different pole tips or a single mass encompassing both pole tips. The chromium masses are of convex contour and of hexavalent chromium composition to provide the masses with hard and smooth surfaces that slide over and do not abrade one another upon impacting.

Abstract: In a dot matrix line printer in which an elongated hammerbank and an opposite conunterbalancing assembly are driven in opposing reciprocating fashion by a motor driven cam, the size of the cam drive motor and the current requirements thereof during startup of the printer are greatly reduced by applying current pulses to the motor in a pattern synchronous with the resonant frequency of the reciprocating cam driven system. The current pulses which are considerably smaller in amplitude than the continuous current conventionally used to produce startup are generated during alternate half cycles of the resonant frequency, causing the cam to rock back and forth until eventually the peak resistance presented by opposite lobes on the cam and the consequent maximum compression of springs within the cam followers coupling the cam to the hammerbank and the counterbalancing assembly is overcome.

Abstract: In a color printer in which a shuttle assembly containing a plurality of impacting print hammers is reciprocated in bidirectional fashion relative to an opposing platen to impact a print paper against the platen through the different color zones of an ink ribbon to print in color, the different color zones of the ribbon are arranged in a repeating pattern along the length thereof enabling the lightest color to be printed first followed by successively darker colors as the ribbon is advanced bidirectionally between the opposite ends thereof. A pair of barrier zones having a blank ribbon zone therebetween are disposed between each adjacent pair of color zones on the ribbon to prevent ribbon contamination due to bleeding of ink between adjacent color zones when the ribbon is wound on a reel. Ribbon contamination is further prevented by the blank ribbon zones which absorb ink that rubs off onto the ribbon guides.