Resistor Matrix Touch Control Using Sequential Row Voltage Sensing
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Solution Overview
Problem
Existing input devices with resistor matrices struggle to accurately determine touch points when multiple points are triggered simultaneously, leading to miscalculations in location detection.
Innovation Solution
A method utilizing a resistor matrix with M first traces and N second traces, where first ends of resistors in a column connect to one first trace and second ends connect to one second trace, coupled to a reference and variable resistors, measuring voltage levels to determine touch points based on resistance ratios and applied forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a switch matrix is used to detect touch points, then the device structure is simple, but multiple simultaneous touch points cause miscalculation of locations
Solution Approach 1:
The patent segments the detection process into multiple sequential phases, applying voltage to different rows in succession. During each phase, only one row is activated, which isolates the measurement to that specific row and eliminates interference from other rows. This temporal segmentation allows accurate detection of multiple simultaneous touch points by processing them sequentially rather than simultaneously.
Solution Approach 2:
The patent applies a preliminary voltage to the selected row before performing the actual resistance measurement. This preliminary action establishes a known voltage state that enables subsequent accurate measurement of the touch point location by comparing the applied voltage with the voltage divider effect caused by the touch.
2Speed
If voltage is applied to multiple rows simultaneously, then detection speed is improved, but measurement accuracy deteriorates due to current interference
Solution Approach 1:
The patent employs periodic action by cycling through each row sequentially and applying voltage in a repeating sequence. This allows the system to maintain high detection speed by rapidly iterating through all rows, while ensuring measurement accuracy by isolating each measurement to a single active row during its designated time slot. The periodic nature enables complete coverage of all touch points across the matrix.
3Measurement precision
If a resistor matrix with voltage division is used, then touch point location can be determined, but multiple simultaneous touches cause current interference and miscalculation
Solution Approach 1:
The patent segments the resistor matrix measurements by activating only one row at a time. This segmentation isolates the voltage division measurement to a single row, preventing current interference from other rows. By measuring each row separately in sequence, the system maintains reliable detection accuracy even when multiple touch points are pressed simultaneously across different rows.
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 allows for accurate determination of touch points even when multiple points are triggered, reducing location miscalculations and enabling precise coordinate detection by using resistance ratios and force strength calculations.
Implementation Method 1
measuring a first voltage level of the each second trace when a first voltage is applied to a first end of the reference resistor and a second voltage is applied to first ends of the M−1 variable resistors
Data Source
AI summary
A method for controlling an input device is provided. The input device has a resistor matrix having M first traces, N second traces and M×N resistors. Each second trace is coupled to a reference resistor and M−1 variable resistors. M and N are integers greater than 1. A first voltage level of each second trace is measured when a first voltage is applied to a first end of the reference resistor and a second voltage is applied to first ends of the M−1 variable resistors via the M first traces. Variations of the first voltage level of each second trace are measured, such that it could be determined whether any touch point of the input device exists according to the variations of the first voltage level of each second trace.