Coordinate detecting apparatus
First Claim
1. An apparatus for detecting the coordinate of a point on a plane, comprising:
- a resistive film means forming the plane, said resistive film means having an effective region used for the coordinate detection, said effective region being substantially rectangular and having a pair of ends disposed in a direction in parallel to a relevant coordinate axis;
a buffer means having an input and an output, said input being connected to one end of said film means and said output being connected to the other end of said film means, said buffer means having substantially infinite impedance and unit voltage gain; and
measuring means connected to said input of said buffer means, to measure an impedance between an end of said film means and ground,wherein the point, whose coordinate on the plane is to be detected, is indicated by applying a load to the point.
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Accused Products
Abstract
A coordinate detecting apparatus for determining the coordinate data of a point on a plane by indicating the point with a touch of a fingertip or other load to the point. The apparatus comprises a transparent resistive film forming the plane (touch panel) and a buffer circuit operating as a voltage follower circuit having substantially infinate input impedance. The buffer amplifier is operatively connected between each selected pair of facing ends of a substantially rectangular region of the resistive film, and equalizes the potentials at the ends. The change of the impedance between one of the ends and the ground is detected in accordance with the touch of the fingertip to the touch panel and is used as an original coordinate data. Further modifications concerning the avoidance of degradation in the detection quality due to fluctuations of the impedance provided by the touch of a fingertip, for example, and the methods to perform 2-dimensional coordinate detection are described.
117 Citations
20 Claims
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1. An apparatus for detecting the coordinate of a point on a plane, comprising:
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a resistive film means forming the plane, said resistive film means having an effective region used for the coordinate detection, said effective region being substantially rectangular and having a pair of ends disposed in a direction in parallel to a relevant coordinate axis; a buffer means having an input and an output, said input being connected to one end of said film means and said output being connected to the other end of said film means, said buffer means having substantially infinite impedance and unit voltage gain; and measuring means connected to said input of said buffer means, to measure an impedance between an end of said film means and ground, wherein the point, whose coordinate on the plane is to be detected, is indicated by applying a load to the point. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification