Resistive Touch Screen Controller Dual Gesture Detection
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Solution Overview
Problem
Existing resistive touch screen controllers require expensive and cumbersome external circuitry for accurate dual gesture recognition, which increases costs and complexity.
Innovation Solution
A processor-configured apparatus with a configurable resistor and current mirror to measure and differentiate currents on resistive screens, determining single and dual touches by comparing current levels and calculating finger positions and gestures using derivatives of current changes over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If prior art resistive TSC measures current through both top and bottom plates with external circuitry, then dual touch position and orientation can be determined, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the bottom plate current measurement circuitry from the system. By using only the top plate current measurements and applying mathematical differentiation, the system achieves dual touch detection without the complex external circuitry previously required to measure bottom plate currents.
Solution Approach 2:
The patent replaces the physical measurement of bottom plate currents with a mathematical approach. Instead of physically measuring currents through separate bottom plate circuits, the system uses differentiation of top plate current measurements to infer dual touch information, substituting mathematical processing for physical measurement infrastructure.
2Measurement precision
If prior art TSC uses voltage division across sensor and reference resistors, then single touch position can be detected, but dual touch recognition requires additional complex measurements
Solution Approach 1:
The patent makes the top plate current measurement system universal by enabling it to perform both single touch and dual touch detection functions. The same top plate measurement circuitry is used for both gesture types, with the processor distinguishing between them through analysis of current patterns and their derivatives, eliminating the need for separate measurement systems.
Solution Approach 2:
The patent changes the parameter being measured from voltage division ratios to current magnitudes and their rates of change. By monitoring how current changes over time (derivatives) rather than just static voltage divisions, the system can distinguish between single and dual touches using the same hardware, reducing complexity.
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
Simplifies circuitry by focusing on top plate current differentials to recognize dual touch gestures, reducing costs and complexity while accurately determining finger positions and gestures.
Implementation Method 1
measuring a current on a top and bottom touch screen... measuring a current on a top and bottom touch screen, wherein the top touch screen is being touched by one finger... measuring a current on a top and bottom touch screen, wherein the top touch screen is being touched by two fingers
Data Source
AI summary
A resistive touch screen controller provides two-finger gesture recognition. Current mirror circuitry, coupled to the XP/XN and YP/YN conductors, generates a screen current IL corresponding to X/y plate currents, and a corresponding mirror current IL/N. A variable resistor receives mirror current IL/N, and a resistance controller sets the resistance value R1 of the variable resistor, and monitors a variable resistor voltage VR1 based on IL/N*R1. A processor determines calibration voltages for the X and Y plates corresponding to the mirror current IL/N for X/Y voltage values of VR1 for a no touch condition, and X/Y offset voltages VOFS and HOFS of VR1 for a two touch condition. For a two touch condition, the processor determines touch resistance relative to no touch, and generates an adjusted X/Y plate resistance ΔX/ΔY based on VOFS/HOFS, and based on X/Y, determines a distance and angle between the two touches.