Low power, high resolution digitizing system with cordless pen/mouse
First Claim
1. In a digitizing system including a digitizing tablet with a digitizing surface and grid conductors in the digitizing surface for receiving electrical signals from a signal source, the improvement comprising:
- (a) a cordless pen, having a conductive stylus including a conductive barrel portion and a conductive tip for producing electrical signals such that capacitive coupling between the conductive tip and the grid conductors causes electrical signals to be produced in the grid conductors in response to electrical signals on the conductive tip;
(b) a tubular conductor disposed coaxially about and spaced from the conductive stylus, the tip of the conductive stylus extending outward beyond an end of the tubular conductor;
(c) an oscillator circuit inside the cordless pen for producing an AC voltage, and means for applying the AC voltage between the conductive stylus and the tubular conductor, the size of the tubular conductor being sufficiently large that the stray capacitance of the tubular conductor is sufficiently greater than the stray capacitance of the conductive stylus to cause the tubular conductor to be an effective virtual ground in order to enable the electrical signal on the tip of the stylus to be effectively capacitively coupled to the grid conductors; and
(d) means within the cordless pen for supplying electrical power to the oscillator circuit without physical connection to any external power source.
4 Assignments
0 Petitions
Accused Products
Abstract
A cordless pen emits a directional electric field from the tip of a conductive pen cartridge. The pen tip is capacitively coupled to embedded major X and major Y conductors in a digitizer tablet, which are scanned to determine which three X conductors and which three Y conductors have the greatest resulting signal levels. A microprocessor calculates the precise pen location from the three largest X signals and the three largest Y signals. A resistive path to ground is provided for each X and Y conductor. A plurality of minor conductors are disposed between each pair of X and Y conductors. A resistive divider circuit linearly distributes the voltage across the pair of conductors among the minor conductors therebetween, and improves the capacitively coupled signal levels and also "localizes" noise signals. The frequency of the pen signal is modulated by several pen switches. Circuitry in the digitizing tablet discriminates the pen frequency to decode the commands represented by switch closures between data scanning operations. In one embodiment of the invention a keyboard is placed on the digitizer tablet. The keyboard includes a groud plane through which a plurality of conductive tips actuated by keys extend to capactively couple an electrical signal to embedded X and Y conductors. The microprocessor interprets the scanned data to determine the identity of each depressed key.
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Citations
38 Claims
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1. In a digitizing system including a digitizing tablet with a digitizing surface and grid conductors in the digitizing surface for receiving electrical signals from a signal source, the improvement comprising:
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(a) a cordless pen, having a conductive stylus including a conductive barrel portion and a conductive tip for producing electrical signals such that capacitive coupling between the conductive tip and the grid conductors causes electrical signals to be produced in the grid conductors in response to electrical signals on the conductive tip; (b) a tubular conductor disposed coaxially about and spaced from the conductive stylus, the tip of the conductive stylus extending outward beyond an end of the tubular conductor; (c) an oscillator circuit inside the cordless pen for producing an AC voltage, and means for applying the AC voltage between the conductive stylus and the tubular conductor, the size of the tubular conductor being sufficiently large that the stray capacitance of the tubular conductor is sufficiently greater than the stray capacitance of the conductive stylus to cause the tubular conductor to be an effective virtual ground in order to enable the electrical signal on the tip of the stylus to be effectively capacitively coupled to the grid conductors; and (d) means within the cordless pen for supplying electrical power to the oscillator circuit without physical connection to any external power source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A computer input device comprising:
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(a) a digitizing tablet including coordinate producing means for producing digital information representative of the coordinates of an interactive device, such as a pen or cursor, that interacts with the digitizing tablet to enable the coordinate producing means to produce the digital information; (b) a separate keyboard aparatus including a plurality of depressable keys and adapted to be positioned on the digitizing tablet; (c) a plurality of interactive means each responsive to a respective one of the keys for interacting with the digitizing tablet when the keyboard apparatus is positioned on the digitizing tablet and that key is depressed to enable the coordinate producing means to produce digital coordinate information representative of the locations of each of the interactive means when the key to which that interactive means is responsive is depressed, whereby the digitizing tablet and the keyboard apparatus operate together as a computer keyboard, and if the keyboard is removed, the digitizer tablet is used as a digitizer tablet in conjunction with a pen or cursor device to produce digital information representative of the location of the pen or cursor device.
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15. A computer input device comprising:
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(a) a digitizing tablet including coordinate producing means for producing the coordinates of a signal source in response to a signal produced by the signal source located adjacent to a digitizing surface of the digitizing tablet; (b) a separate keyboard apparatus including a plurality of depressable keys and adapted to be positioned on the digitizing surface; (c) a plurality of transmitting means each responsive to a respective one of the keys for each acting as a signal source by transmitting a signal to an adjacent location of the digitizing surface when the keyboard apparatus is positioned on the digitizing surface and that key is depressed, the coordinate producing means producing digital coordinate information representative of the locations of each of the transmitting means when the key to which that transmitting means is responsive is depressed, whereby the digitizing tablet and the keyboard apparatus together operate as a computer keyboard, and if the keyboard is removed, the digitizer tablet is used as a digitizer tablet in conjunction with a pen or cursor device that functions as the localized signal source. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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23. In a digitizing system including a digitizing surface and grid conductors in the digitizing surface for receiving electrical signals from a signal source, the improvement comprising:
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(a) a cordless pen, having a conductive stylus including a conductive tip for producing electrical signals to be capacitively coupled between the conductive tip and the grid conductors causes electrical signals to be produced in the grid conductors in response to electrical signals on the conductive tip; (b) a virtual ground conductor disposed adjacent to and spaced from the conductive stylus; (c) an oscillator circuit inside the cordless pen for producing an AC voltage, and means for applying the AC voltage between the conductive stylus and the virtual ground conductor, the stray capacitance of the virtual ground conductor being substantially greater than the stray capacitance of the conductive stylus; and (d) means within the cordless pen for supplying electrical power to the oscillator circuit without physical connection to any external power source, whereby the virtual ground provided by the virtual ground conductor makes it possible for the conductive tip to produce AC signals of sufficient amplitude that the capacitive coupling produces predetermined signal levels in the nearest grid conductor when the conductive tip is near the digitizing surface.
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24. A method of digitizing the coordinates of a preselected point on a digitizing surface with grid conductors therein, the method comprising the steps of:
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(a) producing an AC signal and applying it between first and second ungrounded conductors by means of an AC signal producing circuit in a pen; (b) applying the AC signal, by means of the first and second ungrounded conductors, between a conductive stylus in the pen and a virtual ground conductor that has a much larger capacitance than the conductive stylus, the virtual ground conductor also being included in the pen; (c) positioning the pen so that a conductive tip of the stylus is close to the preselected point of the digitizing surface, and capacitively coupling the AC signal on the conductive tip to the grid conductors near the preselected point; and (d) measuring the levels of signals capacitively coupled onto the grid conductors from the conductive tip and using the measured signal levels to determinate which grid conductors have the largest signals capacitively coupled thereon, to thereby determine the coordinates of the conductive tip of the pen. - View Dependent Claims (25, 26, 27)
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28. A method of inputting information from a keyboard into a computer, the method comprising the steps of:
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(a) pressing a first key of a keyboard; (b) selectively coupling predetermined AC signal to a first conductive element associated with the first key in response to the depressing of the first key; (c) capacitively coupling the AC signal from the first conductive element to a predetermined region of a digitizing tablet and more particularly to grid conductors disposed in a surface of the digitizing tablet in order to produce grid conductor signal levels indicative of the closeness of the various grid conductors to the first conductive element; (d) measuring the levels of the grid conductor signals capacitively coupled thereon from the first conductive element to determine a coordinate of the first conductive element; (e) transmitting the coordinate to a computer and operating the computer to compare the coordinate with a stored menu to thereby determine the identity of the depressed key; and (f) repeating steps (a) through (e) for a second key of the keyboard. - View Dependent Claims (29, 30, 31)
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32. An apparatus for digitizing the coordinates of a point on a digitizing surface with grid conductors therein, the apparatus comprising:
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(a) a pen having a conductive stylus with a conductive tip; (b) means in the pen for producing an AC signal and applying it between first and second ungrounded conductors; (c) a virtual ground conductor disposed in the pen and having a much larger capacitance than the conductive stylus; and (d) means for applying the AC signal, by means of the first and second ungrounded conductors, between the conductive stylus and the virtual ground conductor; (e) means for measuring the levels of signals capacitively coupled onto the grid conductors from the conductive tip; and (f) means for processing the measured signal levels to determine which grid conductor has the largest signal capacitively coupled thereon, to thereby determine a coordinate of the conductive tip of the pen. - View Dependent Claims (33, 34)
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35. An apparatus for digitizing the coordinates of a point on a digitizing surface with a conductive means therein for receiving pen signals capacitively coupled thereto, the apparatus comprising:
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(a) a pen having a conductive stylus with a conductive tip; (b) means in the pen for producing an AC signal and applying it between first and second ungrounded conductors; (c) a virtual ground conductor disposed in the pen and having a much larger capacitance than the conductive stylus; (d) means for applying the AC signal, by means of the first and second ungrounded conductors, between the conductive stylus and the virtual ground conductor; (e) means for measuring the levels of signals capacitively coupled to the conductive pen signal receiving means from the conductive tip; and (f) means for processing the measured signal levels to determine a coordinate of the conductive tip of the pen.
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36. An apparatus for digitizing the coordinates of a point on a digitizing surface with a conductive means therein for receiving transducer signals capacitively coupled thereto, the apparatus comprising:
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(a) a transducer having a conductive member with a conductive end portion; (b) means in the transducer for producing an AC signal and applying it between first and second ungrounded conductors; (c) a virtual ground conductor disposed in the transducer and having associated therewith a much larger capacitance than the conductive member; (d) means for applying the AC signal, by means of the first and second ungrounded conductors, between the conductive member and the virtual ground conductor; (e) means for measuring the levels of signals capacitively coupled to the conductive transducer signal receiving means from the conductive end portion; and (f) means for processing the measured signal levels to determine a coordinate of the conductive end portion of the transducer.
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37. A method of digitizing the coordinates of a preselected point on a digitizing surface with grid conductors therein, the method comprising the steps of:
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(a) producing an AC signal and applying it between first and second ungrounded conductors by means of an AC signal producing circuit in a transducer; (b) applying the AC signal, by means of the first and second ungrounded conductors, between a conductive antenna member in the transducer and a virtual ground conductor that has a much larger capacitance than the conductive antenna member, the virtual ground conductor also being included in the transducer; (c) positioning the transducer so that a preselected portion of the conductive antenna member is close to the preselected point of the digitizing surface, and capacitively coupling the AC signal on the preselected portion of the conductive antenna member to the grid conductors near the preselected point; and (d) measuring the levels of signals capacitively coupled onto the grid conductors from the preselected portion of the conductive antenna member and using the measured signal levels to determinate which grid conductors have the largest signals capacitively coupled thereon, to thereby determine the coordinates of the preselected portion of the conductive antenna member. - View Dependent Claims (38)
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Specification