Sensor Line RC Load Matching for Touch Detection Accuracy
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Solution Overview
Problem
Existing display devices using self-capacitance touch sensing methods face challenges in maintaining consistent RC loads between sensors, leading to potential deviations in touch input detection due to varying distances and positions of sensors and transmitter/receiver components.
Innovation Solution
The display device configures sensor lines and pads to match RC loads between touch sensors, ensuring equal lengths and resistance components, thereby maintaining consistent sensing performance across the touch input detection system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor lines and pads are configured with equal lengths and resistance components to match RC loads, then touch input detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent adjusts the physical parameters of sensor lines (length, width, material) and pads (area, shape, position) to achieve equal RC load values. By changing these geometric and electrical parameters, the invention balances the time constants of different sensors, ensuring consistent touch detection accuracy across the entire touch panel surface.
Solution Approach 2:
The patent applies different configurations to different sensor lines and pads based on their specific positions and functions. Each sensor line-pad pair is individually optimized with appropriate length, width, and resistance values to achieve uniform RC loads, rather than applying a single uniform design to all sensors.
2Area of stationary object
If sensor lines are made longer to connect distant sensors to pads, then sensor coverage area is improved, but RC load increases causing voltage deviations
Solution Approach 1:
The patent compensates for the increased RC load from longer sensor lines by adjusting other parameters such as line width, pad area, or resistance values. This allows distant sensors to be connected to pads while maintaining consistent time constants and voltage levels across all sensors, preventing detection deviations.
Solution Approach 2:
The patent accepts that sensor lines of different lengths are necessary to achieve comprehensive coverage, but compensates for the asymmetry by adjusting other parameters (width, resistance, pad area) to balance the overall RC load, transforming an asymmetric geometric configuration into an electrically symmetric system.
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 ensures accurate and consistent touch input detection without deviations in input and output voltages, enhancing the reliability of self-capacitance based touch sensing in display devices.
Implementation Method 1
Each of the first touch sensor and the second touch sensor is configured to sense a touch input based on self-capacitance
Data Source
AI summary
A display device includes a display substrate having a non-display area at least partially surrounding a display area, and pixels in the display area, and a sensor substrate covering the pixels and a portion of the display substrate. The display device also includes first and second pads in the non-display area, a first sensor on the sensor substrate, a first sensor line connecting the first pad and the first sensor, and a second sensor line connecting the second pad and the first sensor. In addition, the display device includes a sensor transmitter to supply a sensing signal to the first pad during a first period, and a sensor receiver to receive a sampling signal from the second pad during a second period after the first period.