Display Touch Thresholds for Temperature-Driven Capacitance Drift
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Solution Overview
Problem
Existing display devices face challenges in accurately determining touches due to variations in mutual capacitance caused by temperature changes, leading to noise misrecognition or touch non-recognition.
Innovation Solution
A display device with a sensor unit and sensor driver that adjusts the threshold for determining a touch by calculating a change rate in mutual capacitance based on external temperature, using a temperature measurer, change rate calculator, and threshold calculator to generate a threshold that adapts to varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed threshold is used for determining a touch, then the device structure is simple, but touch recognition accuracy deteriorates due to temperature-induced capacitance variations
Solution Approach 1:
The patent implements a dynamic threshold adjustment mechanism where the threshold value changes based on measured temperature conditions. The sensor driver dynamically calculates and applies different threshold values from a pre-stored table corresponding to different temperature ranges, allowing the system to adapt to temperature-induced capacitance variations and maintain accurate touch recognition across varying thermal environments.
Solution Approach 2:
The patent changes the threshold parameter based on temperature measurements. By storing multiple threshold values corresponding to different temperature ranges and selecting the appropriate threshold based on the currently measured temperature, the system adjusts the touch determination criterion to compensate for temperature-induced mutual capacitance variations, thereby resolving the contradiction between fixed simplicity and adaptive accuracy.
2Reliability
If the threshold is adjusted according to temperature, then touch recognition accuracy is improved, but the device complexity increases due to additional temperature measurement and threshold calculation components
Solution Approach 1:
The patent merges the temperature measurement function and threshold adjustment logic into the existing sensor driver circuitry. The sensor driver integrates a temperature measurement unit that measures temperature during touch sensing operations and automatically adjusts the touch determination threshold based on the measured temperature, eliminating the need for separate dedicated temperature sensing and control circuits.
Solution Approach 2:
The sensor driver performs self-adjustment by automatically measuring its own operating temperature and selecting the appropriate threshold value from pre-stored tables. This self-service mechanism eliminates the need for external temperature sensors and complex control logic, as the sensor driver autonomously compensates for temperature effects on touch sensing accuracy.
3Reliability
If a higher threshold is used to prevent noise misrecognition, then false touches are reduced, but legitimate touches at lower capacitance values may be missed
Solution Approach 1:
The patent dynamically changes the threshold parameter based on temperature conditions rather than using a fixed high threshold. By storing and selecting from multiple threshold values corresponding to different temperature ranges, the system optimizes the threshold for each thermal condition, preventing noise misrecognition at high temperatures while maintaining sensitivity to legitimate touches at lower temperatures.
Solution Approach 2:
The threshold value transitions from a static high value to a dynamic value that adapts to temperature conditions. The sensor driver measures temperature and automatically adjusts the threshold in real-time, allowing the system to maintain optimal balance between noise filtering and touch detection sensitivity across varying operating temperatures.
Data Source
AI summary
A display device includes: a sensor unit including first sensors and second sensors; and a sensor driver configured to control the sensor unit, wherein the sensor driver includes: a change rate calculator configured to calculate a first mutual capacitance of the sensor unit, and calculate a change rate corresponding to the first mutual capacitance; and a threshold calculator configured to generate a threshold by applying the change rate to a reference threshold.