Touchscreen Display Touch Position Detection Voltage Compensation
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Solution Overview
Problem
Existing touch panel systems in LCD devices face accuracy issues in touch state discrimination due to variations in readout voltage caused by threshold voltage shifts, sensor gap variations, and temperature dependence, leading to mis-touch discrimination and degraded accuracy.
Innovation Solution
A method and apparatus that integrate a readout current to generate an integrated readout voltage, convert it into digital data, and compensate for variations by comparing differences with reference data, adjusting reset voltages, and using digital processing circuits to determine touch states, thereby enhancing touch position detection capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed reference voltage is used in touch discrimination operation, then the device complexity is reduced, but the measurement precision of touch state determination is degraded due to mis-touch discrimination
Solution Approach 1:
The reference voltage is changed from a fixed value to a dynamically adjusted value that adapts to environmental conditions. The system automatically modifies the reference voltage based on detected variations, enabling accurate touch discrimination across different temperatures and operating conditions without increasing overall system complexity
Solution Approach 2:
The reference voltage parameter is made variable rather than fixed. By adjusting the reference voltage level according to environmental factors such as temperature, the system maintains high measurement precision for touch state determination while avoiding the complexity of more sophisticated sensing systems
2Length of stationary object
If the sensor gap is reduced to improve touch panel integration, then the device thickness is decreased, but the readout voltage stability is worsened due to increased sensitivity to gap variations
Solution Approach 1:
The system implements a feedback mechanism that detects readout voltage variations caused by sensor gap changes and automatically adjusts the reference voltage to compensate. This feedback loop maintains voltage stability despite the reduced sensor gap, enabling thin device design without sacrificing measurement reliability
Solution Approach 2:
The system proactively compensates for expected voltage variations by adjusting the reference voltage before touch discrimination occurs. By anticipating and counteracting the effects of gap variations, the system maintains stable operation in integrated thin designs
3Measurement precision
If transistor threshold voltage compensation is implemented to improve touch detection accuracy, then the measurement precision is enhanced, but the device complexity increases due to additional compensation circuits
Solution Approach 1:
The system uses the existing readout circuitry to detect and compensate for threshold voltage variations without requiring separate compensation circuits. The readout voltage itself serves as the basis for both detection and compensation, enabling high measurement precision while avoiding additional circuit complexity
Data Source
AI summary
A method for detecting a touch position includes integrating a readout current detected at a sensing part to generate an integrated readout voltage, converting the integrated readout voltage into a digital converted readout voltage data and compensating a variation of the digital converted readout voltage data to determine whether the sensing part is touched.