Capacitive Touch Sensor Time-Division Proximity and Contact Detection
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Solution Overview
Problem
Existing touch-sensitive systems face challenges in accurately detecting both proximity and touch states using the same sensor, as separate detection means complicate the sensor structure and degrade the signal-to-noise ratio, limiting detection frequency and accuracy.
Innovation Solution
A capacitive touch sensor system that alternates between hover and touch detection by setting different capacitance thresholds, allowing for simultaneous detection of proximity and touch states using the same sensor matrix, with exclusive hover sensing in non-detect sections and exclusive touch sensing in touch sections, optimizing the sensing cycle for improved accuracy and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate detection means are provided for proximity and touch sensing, then detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies multi-functionality by enabling a single capacitive sensor to perform both proximity sensing and touch sensing functions. The sensor structure uses one set of electrode pairs that can operate in different modes: measuring capacitance changes for proximity detection when no contact is made, and detecting touch positions when contact occurs. This eliminates the need for separate sensor structures while maintaining detection capabilities for both states.
Solution Approach 2:
The patent merges proximity sensing and touch sensing into a unified detection system. By combining both sensing functions into a single capacitive sensor array with shared electrode pairs and processing circuitry, the system reduces structural complexity while achieving both detection goals through different capacitance measurement thresholds and evaluation criteria.
2Device complexity
If time-division sensing is used for proximity and touch detection, then device complexity is reduced, but detection frequency and accuracy deteriorate due to signal-to-noise ratio degradation
Solution Approach 1:
The patent implements periodic action by systematically alternating between proximity sensing mode and touch sensing mode in regular cycles. The control unit periodically switches the sensor operation: during proximity sensing periods, it measures capacitance values to detect hover states; during touch sensing periods, it measures capacitance changes to detect contact positions. This periodic switching ensures both functions receive adequate attention while maintaining a simple unified sensor structure.
Solution Approach 2:
The patent applies dynamics by making the sensing mode adjustable and adaptive rather than fixed. The system dynamically switches between proximity and touch sensing modes based on operational requirements, allowing optimization of detection parameters for each mode while using the same physical sensor infrastructure.
3Device complexity
If the same sensor is used for both proximity and touch detection, then device complexity is reduced, but it becomes difficult to maintain high detection accuracy for both states simultaneously
Solution Approach 1:
The patent applies local quality by implementing mode-specific detection parameters and evaluation criteria for different sensing functions. For proximity sensing, the system uses capacitance threshold comparisons to detect hover states at specific distances. For touch sensing, it uses capacitance change rate and pattern analysis to detect contact positions. Each sensing mode has optimized local parameters tailored to its specific detection requirements, enabling high accuracy for both functions using the same sensor.
Solution Approach 2:
The patent utilizes parameter changes by adjusting detection thresholds, measurement frequencies, and evaluation criteria based on the current sensing mode. The control unit modifies operational parameters dynamically: using different capacitance thresholds for proximity versus touch detection, adjusting sampling rates according to mode requirements, and applying mode-specific signal processing algorithms to maintain optimal detection accuracy for each function.
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
Enables accurate detection of both proximity and touch states with increased signal-to-noise ratio and reduced power consumption by optimizing the sensing cycle and threshold settings, enhancing detection accuracy and efficiency.
Implementation Method 1
a capacitive sensor is configured to detect an input operation based upon a change in capacitance caused by a user's fingertip or the like that is in physical contact with or approaching an operation surface
Implementation Method 2
in a hover state in which the operation body is located close to the operation panel but is not in physical contact with the operation panel, the amount of change in capacitance reaches a hover detection threshold
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3(A)~3(B)
AI summary
Both a proximity state and a touch state are detected accurately using the same sensor means. A touch-sensitive electronic device has a sensor part that detects a capacitance that varies according to a touch or a proximity of a operation body on or to a operation surface, a memory part that stores a reference value used as a basis of calculation of an amount of change in the capacitance and a threshold value used for detection of the touch or the proximity, a determination part that compares the amount of change in the capacitance calculated based on the reference value with the threshold value and determine a state of the touch or the proximity with respect to the operation surface, and a controller that suspends a touch sensing operation in the sensor part during a period when the proximity of the operation body to the operation surface is not detected by the determination part, and suspends a proximity sensing operation in the sensor part during a period when the touch of the operation body on the operation surface is detected by the determination part.