Coordinate input system and input implement used in the system
DCFirst Claim
1. A method of determining the position of an implement on a tablet and the pressure of the implement on a surface of the tablet, the implement including a tuned circuit with a predetermined resonant frequency and a pressure responsive reactance connected in circuit with the tuned circuit, the pressure responsive reactance having a value that changes as a function of the pressure of the implement on the surface of the tablet, the tablet including coils arranged in two coordinate directions, comprising the steps of:
- sequentially exciting at least some of the coils with AC energy having approximately the same frequency as the resonant frequency, the tuned circuit interacting with the AC energy to change the AC current flowing in at least some of the coils so the AC current change at the resonant frequency in at least some of the coils arranged in the two coordinate directions designates the implement position on the tablet and the pressure of the implement on the surface, the AC current change designating the implement on the surface being derived from the same coils of the tablet; and
responding to the changes in the AC current flowing in said same coils that designate the implement position on the tablet and the pressure of the implement on the surface to indicate the implement position and the pressure of the implement on the surface at positions indicated by the implement on the surface.
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Abstract
A coordinate input system has a tablet composed of an X-direction loop coil assembly and a Y-direction loop coil assembly, and an input pen having a tuning circuit the tuning frequency of which is variable about a predetermined frequency. The system has a coordinate detecting function for detecting the X- and Y-coordinate values of position input by the input pen, and a phase detecting function for detecting the change in the tuning frequency of the tuning circuit as a change in the phase with respect to the phase of the predetermined tuning frequency. Information concerning the detected coordinate point, e.g., spread of the coordinate point proportional to the pressure at which the pen is pressed onto the tablet, is computed in accordance with the amount of change in the phase detected by the phase detecting function.
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Citations
30 Claims
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1. A method of determining the position of an implement on a tablet and the pressure of the implement on a surface of the tablet, the implement including a tuned circuit with a predetermined resonant frequency and a pressure responsive reactance connected in circuit with the tuned circuit, the pressure responsive reactance having a value that changes as a function of the pressure of the implement on the surface of the tablet, the tablet including coils arranged in two coordinate directions, comprising the steps of:
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sequentially exciting at least some of the coils with AC energy having approximately the same frequency as the resonant frequency, the tuned circuit interacting with the AC energy to change the AC current flowing in at least some of the coils so the AC current change at the resonant frequency in at least some of the coils arranged in the two coordinate directions designates the implement position on the tablet and the pressure of the implement on the surface, the AC current change designating the implement on the surface being derived from the same coils of the tablet; and responding to the changes in the AC current flowing in said same coils that designate the implement position on the tablet and the pressure of the implement on the surface to indicate the implement position and the pressure of the implement on the surface at positions indicated by the implement on the surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 10, 11)
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- 8. The method further comprising the steps of detecting the amplitude of the current flowing in at least some of the coils to indicate the position of the implement.
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12. Apparatus for determining the position of an implement on a surface, the implement including a tuned circuit with a predetermined resonant frequency and a pressure responsive reactance connected in circuit with the tuned circuit, the pressure responsive reactance having a value that changes as a function of the pressure of the implement on the surface, the apparatus comprising
a tablet carrying the surface and including the coils arranged in two coordinate directions, means for sequentially exciting at least some of the coils with AC energy having approximately the same frequency as the resonant frequency, the tuned circuit interacting with the AC energy to change the AC current flowing in at least some of the coils so the AC current change at the resonant frequency in at least some of the coils arranged in the two coordinate directions designates the implement position on the tablet and the pressure of the implement on the surface, the AC current change designating the implement position on the tablet and the pressure of the implement on the surface being derived from the same coils of the tablet; means responsive to the AC current changes flowing in said same coils that designate the implement position on the tablet and the pressure of the implement on the surface for indicating the implement position and the pressure of the implement on the surface at the indicated implement positions on the surface. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. In combination
a tablet; -
an AC energy source; an implement for movement on a surface of the tablet, the implement including a tuned circuit with a predetermined resonant frequency and a pressure responsive reactance connected in circuit with the tuned circuit, the pressure responsive reactance having a value that changes as a function of the pressure of the implement on the surface, the tablet including coils arranged in two coordinate directions of the surface; means for sequentially exciting at least some of the coils to the AC energy source, the AC energy source having approximately the same frequency as the resonant frequency, the tuned circuit interacting with the AC energy supplied to the coils to change the AC current flowing in at least some of the coils so the AC current change at the resonant frequency in at least some of the coils arranged in the two coordinate directions designates the implement position on the tablet and the pressure of the implement on the surface, the AC current change designating the implement position on the tablet and the pressure of the implement on the surface being derived from the same coils of the tablet; and means responsive to the AC current changes flowing in said same coils that designate the implement position on the tablet and the pressure of the implement on the surface for indicating the implement position and the pressure of the implement on the surface at positions indicated by the implement on the surface. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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28. A coordinate input system comprising:
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a tablet including a first coil assembly having a multiplicity of juxtaposed coils arranged along a first direction, and a second coil assembly having a multiplicity of juxtaposed coils arranged along a second direction; an input implement adapted to be applied with pressure against said tablet having a tuning circuit tuned to a frequency which varies around a predetermined central frequency depending on the pressure with which said input implement contacts said tablet; first direction selection means for successively selecting one of the coils of said first direction coil assembly; second direction means for successively selecting one of the coils of said second direction coil assembly; means for generating an A.C. reference wave having a frequency substantially equal to said predetermined frequency; signal detection means for detecting the A.C. signal of said predetermined frequency; connection change-over means for alternatively connecting said A.C. reference wave and said signal detection means successively to said coils of said first and second coil assemblies selected by said first and second direction selection means; and means responsive to the A.C. signals derived from said first and second direction coils and coupled to said signal detection means by said connection change-over means for determining the position and pressure of the input implement on said tablet. - View Dependent Claims (29, 30)
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Specification