Abstract: In a pen plotter having a pen carriage exchangeably carrying a pen with a downward-facing plotting tip controlled in its movement over a plotting area by control logic and also having a multiple pen-holding rotating turret hub controlled by the control logic, this invention consists of cleaning apparatus for automatically cleaning the tip of a pen after pickup from the turret hub and prior to or just after use. There is a brush ring having upward-facing bristles concentrically carried by the turret hub and additional logic contained in the control logic for moving the pen carriage to the brush ring to place the plotting tip within the bristles prior to or just after plotting with the plotting tip and for rotating the turret hub and the brush ring in combination when the plotting tip is within the bristles whereby to clean the plotting tip with the bristles. The brush ring can be rotated bi-directionally for better cleaning if desired.

Abstract: In a cordless, electro-magnetic digitizing system having a drive circuit outputting a square wave drive signal of known initial polarity to a transducer coil in a cursor to oscillate the transducer coil and cause a magnetic field output therefrom which is detected in an associated tablet, a method of operation and associated apparatus for determining the phase of a response signal induced by the magnetic field from the response signal itself.

Abstract: A hand-operated optical scanning system which can be used to scan a large document in multiple passes. There is a digitizing tablet containing position-sensing circuitry for outputting a signal indicating the position of a sensing coil in an x-y coordinate system associated with a working surface of the digitizing tablet as well as a buffer memory for receiving pixelized data associated with optical scanning of a document. A hand scanner for scanning the document comprises, a case having a longitudinal axis, guide rollers for allowing movement of the case only substantially along the longitudinal axis, a read bar centered on the longitudinal axis and perpendicular thereto for optically scanning a one-dimensional line of pixels and for outputting a signal reflecting an instantaneous scanned image, and a sensing coil carried by the case centered on the longitudinal axis at a pre-established distance from the read bar for being positionally sensed by the position-sensing circuitry of the digitizing tablet.

Abstract: A three-piece, all-plastic idler pulley assembly. There is a first unitary bell end portion having a first circular, inward-facing face with a concentrically-disposed, cylindrical shaft extending outward therefrom and perpendicular thereto. The cylindrical shaft has a concentric longitudinal bore therein. There is also a second unitary bell end portion having a second circular, inward-facing face with a concentrically-disposed, cylindrical projection extending outward therefrom and perpendicular thereto. The cylindrical projection is disposed within the longitudinal bore of the cylindrical shaft whereby the second circular, inward-facing, vertical face is disposed at the end of the cylindrical shaft perpendicular to the first inward-facing face and the second bell end portion is connected to the first bell end portion and spaced therefrom. A plastic cylindrical hub is rotatingly mounted on the cylindrical shaft between the first inward-facing face and the second inward-facing face.

Abstract: In a media transporter which positions media, a method and apparatus is provided for positioning the media for accurate alignment. The method includes the steps of sensing a spatial pattern of densities in the media along a scanned strip, saving the spatial pattern of densities during the initial pass to create a path map from the start position to an end point, comparing subsequently sensed spatial patterns of densities to the path map, and following the path map to repeatedly and accurately position the media at any point along the scanned path. The spatial pattern of densities in the media is sensed by shining a light through the media and sensing the transmitted light intensity.

Abstract: In a push-to-release latch connected to a door/lid revolving about an axis of rotation of a cabinet between open, closed and unlatched, and closed and latched positions wherein the closed and unlatched and closed and latched positions are rotationally displaced from one another, apparatus for determining the status of the latch without sensing the latch. A reflector is carried by the door/lid or the cabinet and a non-contacting optical sensor carried by the other for directing a beam of light from an emitter, for receiving the beam of light as reflected by the reflector, and for outputting an electrical signal at an output thereof as a function of reflected light. The reflector and the non-contacting optical sensor are positioned such that the beam of light strikes the reflector to be reflected thereby when the door/lid is in a closed and latched position and the beam of light does not strike the reflector to be reflected thereby when the door/lid is in a closed and unlatched position.

Abstract: In a pen plotter having a plotting head carrying one half of a pen exchanging mechanism including a holding plate pivotally attached to a plotting head for pivotal movement to raise and lower a pen gripped therein and carried thereby a spring-biased gripping finger pivotally carried by the holding plate for releasably holding a pen, this is a dual-function sensing apparatus for providing a single output signal indicating pen presence and pen up/down position. There is an optical sensor comprising a light source and a light detector separated from the light source by a space and having a sensing surface upon which a beam of light impinges and wherein the level of signal output is a function of the amount of light impinging on the sensing surface.

Abstract: This is an apparatus and associated method for rolling large pieces of a flexible media such as completed plots produced by a plotting pen plotter. The rolling mechanism is placed adjacent an exit of the pen plotter to received ejected media pieces therein. Upon detecting the leading edge of a media piece while in an open position, the mechanism closes to form a guide slot to a cylindrical rolling chamber. The media piece is then urged along the guide slot and into the rolling chamber where it is rolled by a drive roller. Upon detecting the trailing edge of the media piece, the mechanism opens allowing the rolled media piece to fall into a receiving bin. The stationary portion and the rotating portion are formed of a plurality of slats having low contact area edges disposed for media pieces to move along whereby the media pieces move along a low friction path.

Abstract: This invention is a self-adjusting motor mount for holding a driving gear mounted on the shaft of a motor in engagement with a driven gear carried by a back plate disposed in a vertical plane and is particularly useful in a pen plotter. There is a mounting plate carrying the motor and the driving gear. A pivotal mounting carried by the back plate attaches the mounting plate to the back plate at a point above the motor for pivotal movement so as to have the motor pivotally hang from the point. There is a bias spring for resiliently urging the mounting plate to carry the driving gear into engagement with the driven gear. Finally, there is a shock absorber carried by the back plate for absorbing pivotal gear disengaging movement of the mounting plate.

Abstract: This invention is directed to the use of single optical sensor to replace two mechanical sensors in a pen plotter. A light beam is directed through a slot in the plotter's main platen. The light beam is detected to provide a signal output. Servo fan motors of the plotter are turned on when the light beam is broken by media placed into the plotter for plotting as one function. A load sequence of the plotter is started only after a start command is input by a user through a control console and the light beam is broken by media placed into the plotter for plotting as a second function.

Abstract: In an electro-magnetic, cordless digitizer system wherein a transducer emits an AC magnetic field which is detected by a first grid of scanned parallel first wires in a tablet to provide positional data for the transducer in a first axis of a coordinate system and which are detected by a second grid of scanned second wires in the tablet to provide positional data for the transducer in a second perpendicular axis of the coordinate system, a method and associated apparatus for obtaining a phase reference signal; to be used in a demodulator demodulating data signals from the first and second grids of scanned first and second wires.

Abstract: This invention maintains a selected printed ink drop density in an image recording device such as an X-Y plotter having a cartridge of the type which emits discrete ink droplets onto a recording medium and wherein the cartridge is transported along two axes with respect to the medium. There is sensing apparatus for sensing the two-dimensional velocity vector of the cartridge and control apparatus for regulating the rate at which the cartridge emits the droplets in accordance with the two-dimensional velocity vector. Thus, a given printed dot density on the medium is maintained for different angles of travel of the cartridge.

Abstract: This invention is a two-color unitary application and vacuuming head for a liquid toner electrostatic printing system. There is a body having three planar faces angularly displaced from one another concentrically about a pivot point, one of the faces being a first toner face having openings therein communicating with a first network of toner passages in the body, a second of the faces being a second toner face having openings therein communicating with a second network of toner passages in the body, a third of the faces being a vacuum face also having individual openings therein communicating respectively with a third network of toner passages in the body and with a fourth network of toner passages in the body.

Abstract: This invention is directed to a method and associated apparatus for allowing the carriage shafts of a pen plotter to be mounted and aligned quickly and accurately without the introduction of any bending stresses or intra-shaft misalignment. The shafts have conical indentations in the ends thereof. Laterally slidable end caps are bolted over the shaft ends and bolted in place in proper alignment with the shafts. An end cap on one end of the shafts has conical projections in the bottoms of bores therein aligned with and fitting into the shaft ends. An end cap on the other end of the shafts has bolts with conical ends threaded through the bottoms of bores therein aligned with and fitting into the shaft ends. The bolts through the end cap are tightened to hold the shafts in place. An alignment fixture holds the shafts in proper alignment while the end caps are aligned and tightened.

Abstract: The invention is a digitizer circuit in a peripheral system for a computer comprising a moveable instrument and a planar grid in which an excitation signal in one of said instrument and grid generates an induced signal in the other one of said instrument and grid, and wherein the phase difference between said excitation and induced signals is indicative of the position of said instrument with respect to said grid, comprising means for summing said excitation and induced signals to produce a sum signal and means for producing an output signal whose frequency is a function of the amplitude of said sum signal.

Abstract: An apparatus such as a printer or a plotter feeds image-receiving media such as paper by rotation of a shaft, and a media position sensor responds to the rotation of a sensor roller. The apparatus includes a position sensor calibration device having an elastically deformable ring compressible between the shaft and the sensor roller and a calibrator for changing the distance between the shaft and the sensor roller so as to change the amount by which the deformable ring is compressed, in order to adjust the output of the media position sensor for a given amount of media movement. The shaft is connected to one of a pair of media-gripping pinch rollers, the one pinch roller being rotatable by the shaft, and a shaft motor is connected to the shaft. The ring is pinched between the shaft and the sensor roller. The calibrator is a screw threaded through a stationary threaded support and extending toward the sensor roller to push the roller toward the shaft and compress the elastically deformable ring.

Abstract: This is a method and associated apparatus for electrically connecting a coaxial connector plug having a hollow cylindrical center pin inside a cylindrical conductive housing concentrically disposed about the center pin with an insulating support separating the pin and the housing to a coaxial cable having a center conductor inside a hollow conductive shield and separated therefrom by an insulating layer without the use of solder.

Abstract: In a digitizer tablet system employing a tablet having equally spaced parallel grid wires disposed in a plane along an axis parallel to the tablet's upper surface and a pen cursor having a sensing coil disposed concentric with and perpendicular to a longitudinal axis of the pen cursor to develop a characteristic output waveform from electromagnetic inductance between the grid wires and the sensing coil, this invention is the method of compensating a calculation of the position of the pen's tip on the tablet's upper surface and along the axis determined from an interpolation of the characteristic output waveform to find its zero voltage crossing point for tilt of the pen cursor longitudinal axis from perpendicular to the tablet's upper surface comprising using voltage values from grid wires next on opposite sides of the zero crossing point to calculate a pen tilt compensation factor.

Abstract: A method and associated apparatus for frictionally compensating a vector plotter having an X-drive motor for driving plotting apparatus in +X and -X directions and a Y-drive motor for driving plotting apparatus in +Y and -Y directions and logic for applying positive and negative electrical drive currents to the respective motors to affect plotting. Plotter accuracy and associated plot quality are improved by the method which comprises the steps of, providing a memory for holding +X, -X, +Y, and -Y friction compensation factors; prior to the time of plotting with the vector plotter, calibrating the plotter by (1) causing the motors to move the plotting apparatus in +X, -X, +Y, and -Y directions, (2) measuring the friction during the +X, -X, +Y, and -Y directional movement, and (3) calculating and storing the +X, -X, +Y, and -Y friction compensation factors in the memory.

Abstract: In a thermal printer for thermally printing on a wide media with a composite printhead comprising a plurality of standard thermal printheads and including a small diameter print roller for supporting the media adjacent the printhead, an improvement to improve print quality by preventing bowing of the print roller away from the printhead. In one embodiment, there is a first cylindrical support roller mounted parallel to the print roller in rolling contact therewith along the length thereof to oppose vertical movement or deformation of the print roller.