Position detecting apparatus
First Claim
1. A method of determining the position of an implement relative to a tablet, the implement including a tuned circuit with a predetermined resonant frequency, the tablet including coils arranged in two coordinate directions, comprising the steps of:
- sequentially exciting coils of the tablet 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 coils of the tablet as a function of the implement position on the tablet, andresponding to the AC current flowing in coils of the tablet to indicate the implement position.
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Abstract
The position of an implement is determined relative to a tablet including a tuned circuit with a resonant frequency including coils arranged in two coordinate directions. Coils of the tablet are sequentially excited with AC energy having approximately the same frequency as the resonant frequency. The tuned circuit interacts with the AC energy to change the AC current flowing in coils of the tablet as a function of the implement position so the greatest changes in the AC current are in coils of the tablet closest to the implement. Detected values of changes in current as a function of coil position are interpolated to indicate the implement position.
143 Citations
44 Claims
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1. A method of determining the position of an implement relative to a tablet, the implement including a tuned circuit with a predetermined resonant frequency, the tablet including coils arranged in two coordinate directions, comprising the steps of:
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sequentially exciting coils of the tablet 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 coils of the tablet as a function of the implement position on the tablet, and responding to the AC current flowing in coils of the tablet to indicate the implement position. - View Dependent Claims (2, 3)
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4. A method of determining the position of an implement relative to a tablet, the implement including a tuned circuit with a resonant frequency, the tablet including a series of coils arranged in two coordinate directions, comprising:
sequentially exciting coils of the tablet with AC energy having approximately the same frequency as the resonant frequency, the tuned circuit interacting with AC energy to change the AC current flowing in coils in the tablet as a function of the implement position so that the greatest changes in the AC current are in coils closest to the implement, detecting whether a response indicative of the greatest current changes exceeds a predetermined value, thereafter supplying AC current from the source only to the coil having the greatest change in AC current and the coils in proximity thereto, and responding to the AC current flowing in coils in the tablet to indicate the implement position. - View Dependent Claims (5, 6)
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7. A method of determining the position of an implement relative to a tablet, the implement including a tuned circuit with a resonant frequency, the tablet including coils arranged in two coordinate directions, comprising:
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sequentially exciting coils of the tablet 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 coils of the tablet as a function of the implement position so that the greatest changes in the AC current are in coils of the tablet closest to the implement, and interpolating detecting values of changes in current as a function of coil position to indicate the implement position. - View Dependent Claims (8, 9)
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10. Apparatus for determining the position of an implement relative to a tablet, the implement including a tuned circuit with a predetermined resonant frequency, comprising
a tablet including coils arranged in two coordinate directions, an AC source for deriving AC energy at approximately the predetermined resonant frequency, means for sequentially connecting coils of the tablet to the AC source, the tuned circuit interacting with the AC energy from the source to change the AC current flowing in coils of the tablet as a function of the implement position relative to the tablet, and means responsive tot he AC current flowing in coils of the tablet for indicating the implement position.
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22. Apparatus for determining the position of an implement relative to a tablet, the implement including a tuned circuit with a resonant frequency, comprising
a tablet including a series of coils arranged in two coordinate directions, an AC source for deriving AC energy at approximately the predetermined resonant frequency, means for sequentially coils of the tablet to the AC source, the tuned circuit interacting with the AC energy to change the AC current flowing in coils of the tablet as a function of the implement position so that the greatest changes in the AC current are in coils of the tablet closest to the implement, and means responsive to the change in AC current flowing in coils of the tablet for indicating the implement position by detecting whether a response indicative of the greatest current changes exceeds a predetermined value and for supplying AC current from the source only to the coil having the greatest change in AC current and the coils in proximity thereto.
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25. In combination, an implement including a tuned circuit with a predetermined resonant frequency, and apparatus for determining the position of the implement relative to a surface, the apparatus including:
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a tablet for carrying the surface, the tablet including coils arranged in two coordinate directions, an AC source for deriving AC energy at approximately the predetermined resonant frequency, means for sequentially connecting coils of the tablet to the AC source, the tuned circuit interacting with the AC energy from the source to change the AC current flowing in coils of the tablet as a function of the implement position relative to the tablet, and means responsive to the AC current flowing in coils of the tablet for indicating the implement position relative to the surface. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. In combination, an implement including a tuned circuit with a predetermined resonant frequency, and apparatus for determining the position of the implement relative to a surface, the apparatus including:
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a tablet for carrying the surface, the tablet including coils arranged in two coordinate directions, an AC source for deriving AC energy at approximately the predetermined resonant frequency, means for sequentially connecting coils of the tablet to the AC source, the tuned circuit interacting with the AC energy to change the AC current flowing n coils of the tablet as a function of the implement position so that the greatest changes in the AC current are in coils of the tablet closest to the implement, means responsive to the change in AC current flowing in coils of the tablet for indicating the implement position by detecting whether a response indicative of the greatest current changes exceeds a predetermined value and for supplying AC current from the source only to the coil having the greatest change in AC current and the coils in proximity thereto. - View Dependent Claims (39, 40, 41, 42, 43, 44)
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Specification