Abstract: A pointer position detection system for use in determining the position of a pointer relative to a tablet comprising a signal generating system coupled to the tablet for transmitting a driving signal, the signal generating system including a set of conductors for radiating the driving signal and the driving signal including information as to the particular conductor being activated by the signal generating system, a movable pointer responsive to the transmitted driving signal, the pointer including a signal processor responsive to the information and the amplitude of the driving signal on a selected plurality of successive conductors for generating a positional signal and causing the positional signal to be transmitted a selected time after receipt of the information and the amplitudes and further including a transmitter system coupled to the signal processor for transmitting the positional signal, and a signal detector system for detecting the transmitted positional signal.

Abstract: A high accuracy digitizer system for determining the position of a pointer relative to a tablet comprising a tablet having a positional grid thereon, a processor for determining the coarse position of the pointer relative to the tablet, and an error correction system for generating the true position of the pointer relative to the tablet. In a particular embodiment, the pointer includes an electromagnetic transducer for inducing a signal in the positional grid and the processor is coupled to the positional grid for sensing the signal and generating the coarse position of the pointer. The error correction system receives the coarse position from the processor and generates a true position, the positional grid containing positional inaccuracies therein and the error correction system correcting for such inaccuracies.

Abstract: Methods and apparatus are shown for correcting velocity-induced offset errors in a digitizing system when the cursor is moved diagonally across a sensing grid. Primarily, this is a system for reducing the offset error in the actual and depicted cursor position when a pen cursor is moved rapidly over a digitizing screen of a pen-driven computer. It also provides double the number of positional outputs for added accuracy. A triplet of data is formed by taking two samples from one axis and one from the second axis. The two samples are averaged to form one component of the cursor position and then the average along with the single sample from the other axis are output as the positional coordinates. A second sample is then taken from the second axis to form a new data triplet. The averaging process is repeated with the two data points from the second axis and the average along with the second sample from the first axis are output as a next position of the cursor.

Abstract: An improved service station for a printer having a print head comprising a service station for preventing clogging of the nozzles of said print head and a bracket coupled to the service station and rotatably supporting the service station along an extended pivot for restricting movement of the service station to a first selected direction, whereby proper alignment and positioning of the service station with the print head is maintained. The print head moves along a second selected direction toward the service means and the bracket is coupled to the service station along the second selected direction to provide uniform support along the second selected direction. In a particular embodiment, the bracket is an extended hinge-type bracket and is coupled to the service station and a side wall of the printer along the length of the bracket along the second selected direction.

Abstract: An improved ink cartridge comprising an ink chamber, a pressure relief chamber coupled to the ink chamber, and at least one air bleed hole coupling the pressure relief chamber to the ink chamber, the air bleed hole having a capillary dimension for creating a negative pressure on any ink in the air chamber. The pressure relief chamber is positioned below the ink chamber, the ink chamber including an opening to couple the ink cartridge to an ink head, the opening including an automatic shutoff valve, and the air bleed hole is positioned at the bottom of the ink chamber.

Abstract: An improved ink delivery system for an ink jet printer having a print carriage that traverses across a print medium comprising an ink source, a print head, and a coupler for coupling the ink source to the print head, the coupler including a pair of flexible tubes for carrying the ink and a Y-coupler for coupling to the pair of flexible tubes and the ink source, the Y-coupler causing the pair of flexible tubes to initially diverge. A check valve is provided to prevent back siphoning.

Abstract: A high efficiency passive pointer digitizer system comprising first and second sets of orthogonal and substantially coplanar conductors, a signal generator for generating a driving signal selectively along the first set of conductors, a movable pointer inductively coupled to the first and second sets of conductors, the pointer including a tuned circuit responsive to the driving signal for radiating a positional signal, a signal detector for detecting a positional signal induced in the second set of conductors by the tuned circuit responding to the driving signal, and a signal processor coupled to the signal generator and the signal detector for determining the location of the pointer relative to the conductors.

Abstract: An improved sensor system for a printer having a print carriage comprising an ink source, a print head, and a coupler for coupling the ink source to the print head, the coupler including a tube for carrying the ink and sensors for detecting voids in the ink carried by the tubes and positioned in close proximity to the ink source and the print head. A controller is coupled to the sensors and responsive to signals therefrom to stop the print carriage when voids are simultaneously detected by the sensors.

Abstract: The bag includes a selected volume of gas having a selected volume of dead space. The dead space being provided to accommodate expansion of the gas in the event of atmospheric and temperature changes. The dead space is within a range of 9% to 9.5% of the combined volume of the bag. The selected volume of air is sufficient such that complete drainage of an ink supply line to the printhead is allowed.

Abstract: This is a dual-mode digitizing tablet system for providing inputs to a user program. There is a tablet with an active surface and an output connected to the computer. A cursor is moveable over the surface for generating a first signal reflecting the position thereof. Two switch-activating buttons on the cursor generate a second signal when pushed. A position history table holds a last position of the cursor and a menu definition table holds entries defining menu selections associated with the user program as a function of pre-established positions on the tablet. Dual-mode logic is disposed between the tablet and the user program for determining and storing a present location of the cursor, for outputting the present location of the cursor when one of the buttons is pressed, for otherwise outputting both the present location and relative movement of the cursor, and for outputting an indication when the other button is pressed.

Abstract: This is a method and associated implementation logic for plotting circles with a pen plotter to obtain a substantial and unexpected increase in throughput of the plotter when plotting circles having a radius equal to or smaller than a small radius lower limit. The method comprises the steps of, employing an independently calculated chord length and number of chords at the independently calculated chord length for plotting circles having a radius greater than the small radius lower limit; and, employing a maximum chord length which is not separately discernable to the naked eye in a circle of a desired radius and an associated number of maximum length chords when plotting a circle having a radius equal to or smaller than the small radius lower limit. In tested embodiments, the method has provided a twelve-fold increase in plotter throughput when plotting small radius circles.

Abstract: A media position sensing system for a plotter in which a media is driven along at least one edge thereof comprising a plurality of apertures in the media positioned within the width of the edge and an optical detector positioned along the edge for sensing the appearance of the apertures in order to sense a selected position of the media. In a particular embodiment, the width of the apertures are less than one-half the width of the edge and are offset spaced from one another across the width of the edge to present an effective detection capability equivalent to a single aperture having a width equal to the width of the edge. The apertures extend along the length of the media a distance approximately equal to the width of the edge and are located near the end of the length of the media for sensing the end of the media.

Abstract: An apparatus for sensing whether a liquid with a turbulent surface and contained within a vessel has fallen to a level where the liquid is substantially expended. The apparatus includes a light source for emitting light, a light sensor which is sensitive to the light emitted by the light source and which outputs a signal proportionate to the amount of light sensed, and logic for determining from fluctuations in the signal output by the light sensor when the liquid has fallen to the level in the vessel where the liquid is substantially expended. The fluctuations in the signal are caused by randomness in reflections of the emitted light due to the turbulence of the surface of the liquid. Where the vessel has a closed top and the liquid initially fills the vessel, the logic additionally uses the magnitude of the signal from the light sensor to determine when the liquid has fallen to the level where it is substantially expended.

Abstract: A cordless transducer/cursor having a transmitter for use in conjunction with the receiver of a digitizer tablet. The transmitter receives parallel binary signals representing the status of non-positional functions such as command button status and the pressure applied to a stylus of the transducer/cursor and converts these into a serial stream of binary data for electrostatic or electromagnetic transmission to the receiver which, in turn, converts the serial stream into a plurality of parallel binary signals consistent with those received and converted by the transmitter.

Abstract: A printed wire electrostatic printing transducer having two or more rows of styli together defining the recording stylus configuration and an associated method for producing such a transducer by printed circuit techniques. Provision is made for the integration of counter electrodes and multiplexing circuitry with the transducer in a single package.

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: This is a system for holding a supply roll of media in a plotter or the like. One support bar is of fixed length and has a sliding lockable collar for use with different widths of media. Another support bar is of adjustable length for use in plotters employing different widths of media. The end holder for the support bar includes a biased member holding the end in a U-shaped slot to resist lifting from forces on the supply roll as the media is removed.

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: 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.