Apollonius Circle Touch Panel for Non-Rectangular Displays
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Solution Overview
Problem
Resistive touch panels with non-rectangular shapes, such as circular or oval, face challenges in uniform electric field application and high accuracy touch detection due to the need for extensive look-up tables, increased architrave area, and decreased detection accuracy at the edges.
Innovation Solution
A touch panel using the principle of Apollonius' circles with two substrates and point electrodes arranged in a circumference region, connected to calculation and scanning circuits to invert electric voltage polarity and calculate the touched position without a look-up table, reducing the architrave area and maintaining detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional four-wire or five-wire resistive methods are used for non-rectangular substrates, then the touch panel can be manufactured, but uniform electric field application becomes impossible and detection accuracy deteriorates
Solution Approach 1:
The patent changes the electrode configuration from traditional four-wire or five-wire resistive methods to a three-electrode system with point electrodes arranged in a specific geometric pattern. This parameter change enables the application of Apollonius' circle principle, which maintains detection accuracy by using the geometric relationship between three point electrodes to determine touch position, thereby achieving uniform detection performance across non-rectangular substrates
2Measurement precision
If look-up tables are used to compensate for distortion in non-rectangular touch panels, then detection accuracy can be improved, but memory requirements and device complexity increase
Solution Approach 1:
The patent replaces the computational approach of look-up tables with a geometric mathematical principle (Apollonius' circle). Instead of storing pre-computed correction data in memory and performing table lookups, the system uses the inherent geometric relationship between three point electrodes and the touch point to directly calculate position. This substitution eliminates the need for large memory structures and complex computational corrections, reducing device complexity while maintaining high detection accuracy
3Area of stationary object
If the architrave width is reduced to maximize display area in non-rectangular panels, then the display area increases, but the structural integrity and electrode positioning become more difficult
Solution Approach 1:
The patent segments the electrode system into three distinct point electrodes positioned at specific locations on the substrate. This segmentation allows each electrode to be independently positioned and connected to external circuits through separate connection points. The geometric arrangement of these segmented electrodes enables the system to function with reduced architrave width, as the point electrodes can be precisely positioned without requiring large border areas for traditional continuous electrode structures
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach eliminates the need for memory-intensive look-up tables, decreases the architrave area, and maintains high detection accuracy by using the Apollonius' circle principle to determine the touched position, even in non-rectangular shapes.
Implementation Method 1
both having a transparent conductive film (18, 24) formed thereon
Implementation Method 2
the ratio of the distances from the touched position to the two electrodes by using the value of the detected electric voltage
Implementation Method 3
a calculation circuit (12) computing the touched position
Data Source
AI summary
The present invention provides a touch panel with features enabling the external form to be downsized without degrading a detection accuracy of a touch input area and applying an electric voltage to a pair of the electrodes and detecting the output electric voltages inverting the polarity of the voltage. A touch panel of the present invention uses the principle of Apollonius' circle for the touch position detection. Said touch panel is fabricated so that two substrates having a transparent conductive film thereon are place in a manner that said each transparent conductive film is facing each other. A first substrate has one electrode and a second substrate has two pairs of point electrodes. Said two pairs of the point electrodes are arranged in a circumference region of said second substrate. An insulation layer is formed in said circumference region excluding the region where said two pairs of the point electrodes are formed, and wirings extracting said two pairs of the electrodes outwards are formed on said insulation layer and arranged in the region inner than said two pairs of point electrodes are formed.