Touch Sensing Device Differential Capacitance Detection
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Solution Overview
Problem
Existing self-capacitance touch screens require high-frequency clock counting to enhance sensing sensitivity, leading to increased power consumption and reduced detection capacity for finger capacitance.
Innovation Solution
A touch sensing device with a touch screen and sensing circuit that uses differential input methods to detect changes in capacitance between adjacent sensors, generating delays and converting them into digital data to improve touch detection capacity while reducing power consumption, employing a low-frequency dot clock for multiple sensing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-frequency clock counting is used to improve sensing sensitivity, then touch detection sensitivity is improved, but power consumption increases
Solution Approach 1:
The patent changes the sensing method from time-based measurement (requiring high-frequency clocks) to voltage-based measurement. The sensing circuit measures the voltage level on the sensing line after a fixed charging period, eliminating the need for high-frequency clock counting while maintaining detection sensitivity. This parameter change from temporal to voltage measurement resolves the contradiction between sensitivity and power consumption.
2Measurement precision
If high-frequency clock counting is used to improve sensing sensitivity, then touch detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical clock counting system with an electrical voltage measurement system. Instead of using high-frequency clocks and counters to measure touch capacitance changes, the invention uses a sensing circuit that directly measures voltage levels on sensing lines. This substitution simplifies the device architecture by eliminating clock generation and counting mechanisms while maintaining measurement precision.
3Use of energy by moving object
If sensing operation is performed only once within a given period, then power consumption is reduced, but detection capacity for finger capacitance is reduced
Solution Approach 1:
The patent implements periodic sensing operations at multiple time points within a given period. The sensing circuit performs measurements at different moments (e.g., at different phases of the display refresh cycle), enabling multiple detections per frame period. This periodic multi-point sensing increases detection capacity for subtle capacitance changes while the overall power consumption remains controlled due to the efficient voltage-based measurement method.
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 enhances touch sensitivity and detection capacity without high power consumption, enabling multiple touch point recognition and improved sensing performance in both single and multi-touch methods.
Implementation Method 1
detects changes in capacitances of the first and second touch sensors
Implementation Method 2
receives self capacitance signals of a first touch sensor and a second touch sensor adjacent to the first touch sensor among the plurality of touch sensors at differential input method
Data Source
AI summary
A touch sensing device includes a display panel including a touch screen on which a plurality of touch sensors are formed, a touch sensing circuit including at least one sensing unit which receives self capacitance signals of a first touch sensor and a second touch sensor adjacent to the first touch sensor at differential input method and detects changes in capacitances of the first and second touch sensors, and a touch controller which analyzes touch raw data received from the touch sensing circuit and calculates coordinates of a touch input position. The sensing unit generates delays corresponding to a difference between the capacitances of the first and second touch sensors, accumulates the number of delays, converts an accumulated value of the delays into digital data, and generates the touch raw data.