Capacitive Touch Input Device Signal Processing for Detection Accuracy
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Solution Overview
Problem
Existing capacitive touch input devices face challenges in improving detection accuracy while maintaining a compact circuit scale, as they require complex configurations like charge integration circuits.
Innovation Solution
The touch input device incorporates M drive lines and N sense lines arranged in a parallel configuration, forming (M×N) electrostatic capacitances. A signal processor outputs drive signals such that the first amplitude total from one drive line is equal to the second amplitude total from multiple other drive lines, allowing for accurate detection of changes in electrostatic capacitance without increasing circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a charge integration circuit is used to detect changes in electrostatic capacitance, then detection accuracy is improved, but circuit scale increases
Solution Approach 1:
The patent extracts the charge integration function from a separate circuit and integrates it directly into the controller. The controller now performs both drive signal generation and charge integration functions, eliminating the need for external charge integration circuits and reducing overall circuit scale while maintaining detection accuracy
Solution Approach 2:
The controller is designed to perform multiple functions: generating drive signals for the drive electrode, integrating charge from the sense electrode, and processing detection results. This multi-functional design consolidates what would traditionally require separate circuits, reducing circuit scale while improving detection accuracy
2Measurement precision
If the second drive voltage having an opposite phase is applied to remaining drive electrodes, then detection accuracy is improved, but the number of drive signals increases
Solution Approach 1:
The controller applies drive voltages with opposite phases in a periodic manner, switching between different phase configurations. This periodic application of opposite-phase voltages enables accurate detection of electrostatic capacitance changes while managing the complexity of drive signals through systematic timing control
Solution Approach 2:
The patent applies drive voltages with opposite phases to different drive electrodes at different times. By inverting the phase relationship between drive electrodes systematically, the controller can distinguish between capacitance changes caused by touch and those caused by other factors, improving detection accuracy without requiring all electrodes to simultaneously handle complex signal configurations
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 configuration enhances detection accuracy while reducing the circuit scale, enabling reliable touch position identification and suppressing noise, thus improving overall performance.
Implementation Method 1
capacitive touch input device that detects a touched position in accordance with a change in electrostatic capacitance
Implementation Method 2
(M×N) electrostatic capacitances formed between the M drive lines and the N sense lines
Implementation Method 3
outputs a second drive signal having a phase opposite to a phase of the first drive signal to each of at least two second drive lines other than the first drive line
Data Source
AI summary
A touch input device includes M drive lines; N sense lines; (M×N) electrostatic capacitances; and a signal processor configured to output a first drive signal and detect a change in a plurality of electrostatic capacitances of the (M×N) electrostatic capacitances. The signal processor outputs the first drive signal to the at least one first drive line and outputs a second drive signal having a phase opposite to the first drive signal to each of at least two second drive lines. The signal processor outputs the first drive signal and the second drive signal so that a first amplitude total, which is obtained by multiplying an amplitude of the first drive signal by the number of first drive lines, is substantially equal to a second amplitude total, which is obtained by multiplying an amplitude of the second drive signal by the number of second drive lines.