Resistive Touch Panel Circuit for Multi-Touch Detection
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Solution Overview
Problem
Resistive film touch panels are unable to distinguish between single-touch and multi-touch operations due to similar output voltages, leading to invalidation of multi-touch inputs as errors.
Innovation Solution
A control method for a touch panel that applies bias voltages and detects panel voltage and current to determine touched coordinates, utilizing the change in panel current to differentiate between single and multi-touch states and calculate the coordinates of multiple points by monitoring the combined resistance and current changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If voltage-based coordinate determination is used in resistive film touch panels, then the touch position can be determined, but multi-touch operations cannot be distinguished from single-touch operations
Solution Approach 1:
The patent combines voltage detection and current detection methods to determine touch coordinates. By merging these two detection approaches, the system can distinguish between single-touch and multi-touch operations while maintaining accurate coordinate determination, thereby enabling multi-touch operations in resistive film touch panels.
Solution Approach 2:
The patent changes the detection parameter from voltage-only to include both voltage and current measurements. By monitoring current changes in addition to voltage, the system can identify multi-touch states through characteristic current patterns, thus improving adaptability to multi-touch operations without sacrificing measurement precision.
2Reliability
If only voltage detection is implemented, then the device complexity remains low, but the ability to detect multi-touch states is insufficient
Solution Approach 1:
The patent makes the existing resistive film touch panel structure serve multiple functions: it can detect both single-touch and multi-touch operations using the same physical structure. By adding current detection capability to the existing voltage detection system, the panel achieves multi-functional operation without requiring fundamentally different detection mechanisms.
Solution Approach 2:
The patent introduces current as an intermediary parameter to mediate between the touch input and the detection system. Current changes serve as an additional signal that helps distinguish multi-touch states, acting as a mediator that provides supplementary information without completely redesigning the detection architecture.
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
Enables accurate detection and determination of multi-touch states and coordinates, allowing for valid multi-touch operations by differentiating panel current changes, thus supporting multi-touch functionality in resistive film touch panels.
Implementation Method 1
a first resistive film arranged such that one edge thereof is connected to the first terminal and an edge that is opposite to the aforementioned one edge is connected to the second terminal, and a second resistive film arranged with a gap between it and the first resistive film such that one edge thereof is connected to the third terminal
Implementation Method 2
When the user touches multiple points on the touch panel, the combined resistance value of a path from the first terminal to the second terminal is reduced, and accordingly, the panel current changes according to the reduction in the combined resistance
Data Source
AI summary
A first resistive film is arranged such that one edge thereof is connected to a first terminal, and an edge that is opposite to the aforementioned edge is connected to a second terminal. A second resistive film is arranged with a gap between it and the first resistive film such that one edge thereof is connected to a third terminal. A voltage generating unit applies a predetermined first bias voltage and a predetermined second bias voltage to the first terminal and the second terminal, respectively. A voltage detection unit detects a panel voltage that occurs at the third terminal. A current detection unit detects a panel current that flows through a path including the first terminal, the first resistive film, and the second terminal. A computation unit determines the coordinates touched by the user, based upon the values of the panel voltage and the panel current.