Abstract: A support arm for use in a pen plotter having a platen with a platen extension in front of it spaced to provide a slot therebetween to rotatably support a pinch roller above the platen to prevent the edges of plotting media inserted between the platen and the pinch roller from entering the slot. The arm is slidably supported under the platen on one end and passes through the slot to rotatably support a pinch roller above the platen on the opposite end. The arm has a bridging finger extending horizontally in the slot from a point adjacent the opposite end towards the plotting media from a side edge thereof. Preferably, the bridging finger is of a width substantially equal to the width of the slot and has a top surface at the same level as a top surface of the platen.

Abstract: This is a pair of improvements for a plot rolling mechanism for a pen plotter or the like having a rolling mechanism with an entry opening and a receiving bin for receiving rolled plots. The first improvement comprises a sealing mechanism for sealing the entry opening during plotting, the sealing mechanism being rotatable between a sealing position blocking the entry opening and a retracted position not blocking the entry opening and apparatus for rotating the sealing mechanism between the sealing position and the retracted position.

Abstract: The invention is a polychromatic pen cartridge for recording device such as a color plotter, or printer, for recording a color image on a recording m edium. The color image is characterized by a line width. The invention has tapered tubular lumens with plural hollow elongate lumens. The tubular lumens have a tip end facing the recording medium and spanning a distance on the recording medium on the order of the line width. Each of the lumens has an opening at the tip end and a large input opening at the other end. A plurality of separate ink reservoirs are connected to corresponding ones of the lumens at the input openings thereof. There are also valving apparatus for individually controlling ink flow from each of the ink reservoirs to a respective one of the lumens.

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 phase lock loop (PLL) circuit which includes an input for inputting an incoming signal which is to be tracked, a phase lock loop subcircuit, a phase state indicator subcircuit, and a synchronized blanking window generator. These elements create a phase lock loop circuit capable of producing a stable output which closely tracks the incoming signal, even when the incoming signal shifts in phase by 180 degrees. The phase state indicator subcircuit detects a phase reversal in the incoming signal and outputs a signal indication such. This indicating signal is used by the phase lock loop subcircuit to produce a stable reference signal tracking the incoming signal most of the time. However, during a short period of time between the inversion of the incoming signal and the output of the indicating signal by the phase state indicator subcircuit, the synchronized blanking window generator provides a signal to the phase lock loop subcircuit which is used to stabilize the reference signal.

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: 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: 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 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 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 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: 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.

Abstract: Methods and apparatus for setting the signal-sampling period of each grid wire in a digitizing tablet having grid wires that are sequentially and repetitively scanned to develop a positional signal related to a cursor so as to reduce jitter associated with non-movement of the cursor and signal error associated with rapid movement of the cursor. The method comprises setting the signal-sampling period of each grid wire to a longest signal-sampling period the digitizer tablet is designed to employ if the cursor is not moving and setting the signal-sampling period of each grid wire to a value inversely related to the present speed of movement of the cursor such that the faster the present speed of movement of the cursor the shorter the signal-sampling period of each grid wire as compared to the longest signal-sampling period the digitizer tablet is designed to employ. The present position of the cursor is then saved as the prior position of the cursor for the next time the steps of the method are performed.

Abstract: The invention is a media positioning system for determining the position of the media relative to reference positions thereof in a media transporter in which media having opposed faces is transported along a path of a track including a spatially varying pattern on the media, the alignment system including a light sensor having a light-sensitive surface facing one face of the media in at least approximate registration with the track, the light-sensitive surface including plural sections, the sensor producing plural signals at an output thereof proportional to the intensity of light impinging on respective ones of the plural sections of the light-sensitive surface, a light source facing the other face of the media and directing a beam of light through the media onto the light-sensitive surface, whereby the plural signals vary as a function of the spatially varying pattern of the track as the media is transported along the path of the track, and signal detection and logic apparatus for converting the plural sign

Abstract: This is a hand cursor for a digitizing system allowing easier positioning of the cursor at the points to be digitized. The cursor includes a quasi-sight window having a CCD panel for viewing a 2-dimensional area and an LCD panel for displaying it to the user. There is a vertical positioning line on the panel. A position signal generator is disposed in the cursor for continuously generating and outputting positional data from which a reference point position and the orientation of the positional line on the tablet surface can be dynamically determined. There is also position determination logic for inputting the electrical signal output from the CCD panel and the positional data from the positional generator and for determining a point on the tablet surface where the positional line crosses a line contained in a drawing disposed on the tablet surface over which the quasi-sight window is positioned as a point to digitize.

Abstract: In an electromagnetic digitizer tablet having a grid of receptor wire disposed below a working surface over which a cursor emanating a magnetic field detected by the receptor wires is moved, this invention is an improvement to reduce electrostatically-caused jitters in data from the receptor wires. A grounded electrically conductive shield disposed between the grid of receptor wires and the working surface. The grounded electrically conductive shield is of a material and thickness to pass the magnetic field without substantial attenuation while conducting any electrostatic energy forming thereon to ground. Both conductive ink and a very thin metal foil can be used for the shield. The digitizer tablet is also shown embodied in the input/display device of a pen-driven computing system.

Abstract: This is a low-cost cursor for a digitizing tablet which provides the user with the feel of a mouse. There is a case bottom piece for sliding on the surface of the digitizing tablet and a pair of microswitches. A printed circuit board fits in the case bottom piece with the pair of switches mounted behind one another thereon. A transparent front-piece is disposed over the printed circuit board with slots therethrough through which the switches are disposed. The front-piece has a front portion extending outward from a front end and parallel to the bottom surface and has an annular armature formed thereon with a concentric pair of cross-hairs and a sensing coil of wire wound around the armature. A connecting cable of wires is connected to the sensing coil of wire and the switches. There is also a case top piece attached over the case bottom piece to form a hollow case which is tapered from back to front to give the case the feel of a mouse.

Abstract: In a pen plotter having plotting media supplied in the form of plotting media supply rolled around a hollow tube, this is a method and apparatus for automatically identifying the type of, and measuring the amount of, plotting media contained on the plotting media supply roll. A circular barcode strip is secured to the inner surface of the supply tube and is optically scanned to reveal the identity of the media contained on the supply roll. Said barcode strip's properties allow for the determination of the rotational velocity of the supply roll which, when used in conjunction with other known and easily derivable pieces of information, also allow for the precise calculation of the amount of media remaining on the roll. Knowing the identity of the media on the roll allows the plotter to handle the media in a manner consistent with its properties. Knowing the quantity of media remaining allows both media low and media out conditions to be determined and alarmed.

Abstract: In a cordless digitizing system wherein a cordless stylus having a manually operable button thereon transmits positional pulses to a tablet at a carrier frequency this invention is apparatus for transmitting status information about the button to the tablet. There is first status logic associated with the stylus for sensing the present status of the button and for encoding and transmitting the present status of the button as a binary 1 or 0 employing a first unique and recognizable sequence of carrier frequency cycles as a binary "1" and a second unique and recognizable sequence of carrier frequency cycles as a binary "0". Then, there is second status logic included in association with the tablet for recognizing the first unique and recognizable sequence of carrier frequency cycles to be a binary "1", for recognizing the second unique and recognizable sequence of carrier frequency cycles to be a binary "0", and for determining the present status of the button therefrom.