Abstract: In a pen plotter having a pen carriage moving laterally along a support beam over a plotting media, cutting apparatus for cutting the plotting media includes a first member carried by the pen carriage for lateral movement in combination therewith, a second member carried by the first member for movement perpendicular to movement of the first member between a first position adjacent the plotting media and a second position removed from the plotting media, a cutting blade carried by the second member for movement therewith such that when the second member is in the first position the cutting blade has a cutting edge thereof positioned to cut the plotting media and when the second member is in the second position the cutting edge does not contact the plotting media, a first abutting surface disposed adjacent one end of lateral movement of the pen carriage, a second abutting surface disposed adjacent an opposite end of lateral movement of the pen carriage, and a camming apparatus carried by the pen carriage and c

Abstract: A control system and method of operation for controlling the operation of a finished plot handling and rolling mechanism of a plotter. If the finished plot is not properly gripped for rolling, the rolling process is aborted and the plot ejected unrolled. During rolling, power to the driving mechanism is maintained at a level which will keep the media taut and prevent over powering. At the plot end, the media is made taut over the platen for consistent cutting. The trailing end is then accelerated at a level which will overcome static friction of the previously rolled portion and prevent buckling of the trailing portion.

Abstract: In a mechanical device in which a member is moved by an electrical actuator through an electronic and mechanical linkage, apparatus for compensating for changes in system gain to allow precision movement with non-precision components. There a sensor for accurately determining positions of the member, control logic connected to provide a control signal to the actuator, and an adjustable gain control for adjusting the gain of the control signal. Compensation logic is connected to receive positional signals from the sensor, for applying a control signal to the actuator to move the member to a target position closest to a desired final position, for adjusting the gain of the control signal with the adjustable gain control until the member is located at the target position within acceptable tolerance limits, and for then employing that gain to move the member to the desired final position. The method associated with the apparatus can be done in real-time or by pre-calibrating in advance.

Abstract: A device for indicating the phase of the a full-frequency alternating current (AC) magnetic field signal transmitting from the pointing device of a cordless digitizer and for determining if the phase of a half-frequency alternating current (AC) magnetic field signal transmitting from the pointing device is approximately the same or approximately inverted from an immediately preceding half-frequency signal from the pointing device. The indication of the phase of the full-frequency pointing device signal is used by the digitizer logic circuits to determine the location of the pointing device on the tablet's sensing surface. The information concerning the change in phase of the half-frequency signal is used by the digitizer logic circuits to decode the status of various pointing device buttons. If the phase in the induced half-frequency signal is unchanged from the last, this no-change condition represents one binary state. If the phase has changed, the condition represents the other binary state.

Abstract: Apparatus and an associated method for ascertaining the operational status of a pen in a vector plotter in which a pen is moved into contact with a paper web at a test location, the pen is moved relative to the web and an optical detector is used to determine whether or not the pen is drawing a line on the web. The web is moved from a supply roll to a take-up roll to move the test area on the web to an optical testing location. The absence of a line after a pre-determined period of web movement time signals the inoperative status of the pen and the detection of a line by the pen within that pre-determined period of movement time signals that the pen is operative. Quality and proper line width of the line can also be determined.

Abstract: Apparatus for automatically determining if roll or cut-sheet media is being used in a plotter or similar device and for automatically setting some of the operating parameters in lieu of manual input by an operator. The roll media has a hole therein adjacent the roll end. An optical sensing pair senses the passage of light through the media at a point passed by the hole. If a suspected end is found, the media is moved a distance greater than the hole diameter. If light is still detected, the edge of a cut sheet has been detected. If light is no longer detected, it was a hole and the end of a roll of media has been detected. By being able to determine the type of media involved, the plotter logic can measure the width of the media and then get a desired length from a look-up table and thereafter determine if there is a proper length of media available for the plot.

Abstract: An actuator mechanism for a pencil carriage in which a motor is coupled to a lead holder to move the lead holder relative to a drawing media surface, a pusher mechanism moves a lead carried by an internal of the lead holder relative to the position of the lead holder and the drawing media surface independently of the movement of the lead holder and a plotter control and sensors coupled thereto are provided for synchronizing the operation of the motor and the pusher mechanism to control the position of the lead relative to the lead holder and the drawing media surface. In a particular embodiment, the pusher mechanism includes a pusher rod for engaging the lead, a movable rack and a pinion gear engaged therewith, the movable rack being coupled to the pusher rod to move the lead, and a motor for driving the pinion gear.

Abstract: This is a pen cursor structure for a positional digitizing device such as a digitizing tablet or a pen-driven computer. It comprises a structure of an electrically insulating material having a plurality of areas for receiving and carrying electrical components, an inner structure having a plurality of electrical contacts disposed within the areas and a plurality of electrical traces interconnecting the plurality of electrical contacts. The structure is curved about a longitudinal axis to fit within an outer, hollow, pen-shaped housing.

Abstract: An integrated voltage controlled oscillator (VCO) circuit which utilizes the relative capacitance ratio between capacitors and the relative resistance ratio between resistors in an integrated circuit (IC) to output a signal having a predictable frequency for a given control signal voltage. The VCO output frequency will not vary more than 3.0% from one IC chip implementing the VCO circuit, to the next. This low variance between IC chips is derived from the phenomenon whereby the respective ratios of capacitance and resistance between capacitors and resistors in the IC will not vary more than .+-.1.5% from the ratios of like capacitors and resistors on other IC chips. The integrated VCO circuit includes a control signal subcircuit, integrator subcircuit, filter subcircuit, and comparator unit subcircuit.

Abstract: A combined display and electromagnetic digitizing input device for pen-driven computers. There is a graphics display panel having a viewing surface and a back surface. A first grid of parallel transparent conductors for connection to electromagnetic digitizing electronics to sense the location of an electromagnetic stylus is disposed over one of the surfaces. A second grid of parallel transparent conductors for connection to the electromagnetic digitizing electronics is disposed over the first grid of parallel transparent conductors electrically insulated therefrom and perpendicular thereto. The two grids are constructed of flexible transparent substrates carrying a plurality of transparent indium tin oxide conductors thereon. For improved performance, shielding is provided in the form of a sheet of a transparent conductive material connected to ground potential disposed below the grids of conductors as well as a sheet of a metal foil disposed across the extents of the grids of conductors.

Abstract: Three terms (X,Y,"Error") are combined in a single floating-point number in an advanced microprocessor to compute pixel addresses. The floating-point number is reconverted to integer form in multiplexers operating in a mode determined by slope, relative to unity, of the line to be defined by the pixels. The output of the multiplexers is enhanced by a look-up table to produce color data, which are converted to analog form for display. Speed of operation is greatly augmented by the use of floating-point arithmetic to compute the pixel addresses.

Abstract: A device for imparting a signal phase status of an alternating current (AC) magnetic field signal transmitting from a cursor in a cordless digitizer. The device includes an apparatus for causing the cursor to temporarily emit a signal having a frequency which is lower than the frequency of a basic cursor signal, and an apparatus for determining and imparting the signal phase status of the AC magnetic field signal transmitting from the cursor as derived from the temporarily emitted lower frequency signal.

Abstract: A media stripper mechanism for a plotter in which the media is supported by a support having a recess therein adapted to be covered by the media. A stripper is positioned external of the support and is adapted to be extended a preselected distance into the recess. A mover is provided for moving the stripper into the recess prior to the covering thereof by the media, whereby the media is stripped from the support by the stripper.

Abstract: A media cutter mechanism for a plotter in which the media is supported by a rotating support having one or more continuous recesses therein positioned to be at least partially covered by the media, the media being stationary with respect to the rotating support. One or more cutters are positioned external of the support and are movable a preselected distance into the recesses. Movers are provided for moving the cutters into the recesses to cut the media covering the recesses. In a particular embodiment, a plurality of individual cutters are employed and a plurality of commonly driven individual cams interact with the cutters for individually moving the individual cutters into the recesses. A controller is provided for controlling the individual cams to cut the media into preselected widths. In addition, a driver is provided for commonly driving the individual cutters.

Abstract: In a pen cursor for use in performing writing motions on the surface of a tablet, this is a sensor for mounting in a tip portion of the pen cursor to develop a signal output indicating longitudinal force on a writing tip of the pen cursor. A tip member extends from the tip portion of the pen cursor and is mounted for longitudinal movement. It has a plunger portion extending therefrom within the pen cursor. A resistive member and a conductive member are disposed within the pen cursor behind the plunger portion. The plunger portion forces the resistive member and the conductive member together in electrical contact over a contacting area which is directly proportional to the amount of longitudinal pressure on the plunger portion. A voltage is connected across the contacting area whereby resistance as a function of longitudinal pressure on the plunger portion can be measured.

Abstract: A combined shield member and grid shield for a digitizer tablet having conductive grids on a flexible substrate comprising a sheet of a metal having a high magnetic permeability substantially the size of a square X-Y axis coordinate system of the digitizer tablet shielding the flexible substrate. Preferably, the metal has an initial permeability of at least 5,000. The metal can be a NiFe alloy having an initial permeability sufficiently high to qualify it as a .mu.-metal. Typically, the sheet of metal is a square sheet of substantially the size of a square X-Y axis coordinate system of the digitizer tablet and the flexible substrate has edge portions which extend beyond side edges of the sheet of metal and are wrapped around the side edges. An alternate embodiment employs the high permeability shield positioned between two rigid substrates carrying the grids and interconnects respectively. A conductive metal foil over the surface of the substrate corrects any signal errors introduced by the shield.

Abstract: In order to determine without ambiguity the grid sections on which the pointer is located in a cordless electromagnetic digitizer having x and y locating grids, a third, "phase" grid has conductors that form elongated, narrow open loops, spaced so that each location on the work surface is enclosed by loops formed by a minority of the phase grid conductors. Any phase grid conductor with sufficient induced voltage can serve as a phase reference to determine the relative phases of the signals induced in all of the phase grid conductors. A phase grid conductor determined to have the relative phase of the minority can then serve as phase reference to identify the locating grid section unambiguously, and digitize the pointer location.

Abstract: An actuator mechanism for a plotter carriage adaptable for use in either a pen plotter or a pencil plotter mode in which a coupler engages both a support for a pen holder and a support for a lead holder and a motor and an actuator arm coupled to the motor are provided for driving the coupler relative to a drawing media surface. An interlock and a sensor are provided to enable the motor, actuator arm and coupler to be coupled to a pencil actuator mechanism and to determine whether the plotter carriage is being used in a pen plotter or a pencil plotter mode.

Abstract: A pen force gage for a pen plotter for determining whether the force of a pen positioned by a pen support onto the surface of a drawing media in the pen plotter falls within an acceptable range. The pen force gage includes structure for aligning or positioning the gage within the pen plotter so as to enable the gage to measure the force of the pen; a pivotable arm configured at one end to interact with the pen support as the pen moves toward the surface of the media and at the other end to support a movable weight to determine the force to be applied by the pen on the surface of the media; and an indicator and a reference mark for determining whether the force falls within the acceptable range.

Abstract: In a pen plotter, a plotting system for generating and delivering vaporized ink to an aerosol pen which is designed to deliver a precision, controlled stream of ink to the media surface without having to come into contact with it. This is achieved by vaporizing ink in a chamber and delivering it to an ink vapor aerosol pen through tubing which is designed to absorb and recover any ink vapor droplets that may have condensed therein and thus obstruct the vapor path. The aerosol pen is designed to dispense the ink vapor as a stream which converges to a fine point thereby allowing a precise image to be plotted on the media surface. As with the vapor delivery tubing, the aerosol pen is also designed to absorb and recover condensed ink vapor droplets. An interrupter moved into and out of the ink vapor stream to act as a valve for the stream so as to stop and start marking on the media by the stream. Intercepted ink is recycled back to the holding chamber.