Resistive Touch Panel Two-Point Coordinate Calculation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Resistive touch panels cannot accurately calculate the input coordinates of two points touched simultaneously, limiting their functionality in applications requiring multi-point input information.
Innovation Solution
A 4-wire resistive touch panel apparatus with a control unit that applies and measures voltages across orthogonal terminals on two overlapping resistive films, using calculated terminal voltages to determine the positional relationship and distance between two points of contact, enabling the derivation of central and input coordinates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional resistive touch panel is used, then the structure is simple and easy to manufacture, but it cannot accurately calculate the input coordinates of two points touched simultaneously
Solution Approach 1:
The patent segments the touch detection process into multiple measurement phases: first measuring terminal voltages when only one resistive film is pressed, then measuring when both films are pressed simultaneously. This segmentation allows the system to separately obtain resistance values for each film and calculate two-point coordinates by combining these measurements, thereby enabling multi-point input capability while maintaining calculation accuracy.
Solution Approach 2:
The patent performs preliminary measurements of terminal voltages before the final coordinate calculation. By first measuring voltages in a single-point press state and storing these reference values, the system prepares necessary data in advance that enables accurate two-point coordinate calculation when both films are pressed, thus improving measurement precision for multi-point input.
2Loss of information
If the panel is touched at two points, then the resistance between the terminals decreases, but the ability to calculate specific input coordinates is lost
Solution Approach 1:
The patent implements a feedback mechanism where terminal voltages are measured and used to calculate resistance values, which then feed into coordinate calculation algorithms. By continuously measuring terminal voltages under different pressing conditions and using these measurements to derive resistance values and coordinates, the system recovers coordinate information that would otherwise be lost in two-point touches, maintaining both information integrity and detection reliability.
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 calculation of input coordinates for two-point touches, enhancing the panel's functionality as an input device for systems like POS terminals and personal computers by reducing measurement and calculation errors.
Implementation Method 1
When a user's touch allows the resistive films to come into contact with each other, terminal voltages change. Based on these terminal voltages, the input coordinates of the single point at which the touch panel has been touched can be calculated.
Implementation Method 2
The application unit is configured to apply a voltage between the first terminal and the second terminal at a first timing. The measurement unit is configured to measure a voltage of each of the third and fourth terminals at the first timing.
Data Source
AI summary
According to an embodiment, a control apparatus controls a touch panel includes a first resistive film includes a first terminal and a second terminal and a second resistive film includes a third terminal and a fourth terminal, the first and second resistive films being laid on top of each other with a gap between the resistive films. The control apparatus comprises an application unit, a measurement unit and a calculation unit. The application unit is configured to apply a voltage between the first terminal and the second terminal at a first timing. The measurement unit is configured to measure a voltage of each of the third and fourth terminals at the first timing. The calculation unit is configured to derive a positional relationship between two points at which the touch panel has been touched based on the voltages of the third and fourth terminals measured at the first timing.