Electrostatic Sensor Gloved Touch Detection
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Solution Overview
Problem
Capacitive touch sensors have limited detection sensitivity, particularly when used in environments such as cars where a driver may wear gloves, leading to reduced accuracy in detecting touch inputs.
Innovation Solution
The design includes a capacitive touch sensor with a first and second electrode group, connected to detection circuits and alternating-current sources, where alternating voltage is applied to selected electrodes to enhance detection sensitivity by maintaining electric field density and directivity, thereby improving position detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional capacitive touch sensor with a single electrode group is used, then the device structure is simple, but the detection sensitivity is insufficient to detect touches through gloves
Solution Approach 1:
The electrode system is divided into multiple electrode groups (first electrode group and second electrode group) with different orientations (X-direction and Y-direction diamond-shaped electrodes). Each electrode group independently contributes to detection sensitivity, allowing the system to detect touches through gloves by combining the detection capabilities of multiple segmented electrode structures.
2Measurement precision
If alternating voltage is applied to all electrodes simultaneously, then the electric field coverage is maximized, but the directivity and precision of position detection are reduced
Solution Approach 1:
The controller applies alternating voltage to electrode groups in a periodic, sequential manner rather than simultaneously. The first electrode group and second electrode group are alternately activated, creating time-separated electric fields that maintain directivity. This periodic activation pattern enables precise position detection while managing control circuit complexity through systematic switching.
3Reliability
If the electrostatic capacitance change is small (as occurs with gloved touches), then the touch sensor cannot reliably detect the input, but increasing the electrode density increases manufacturing complexity
Solution Approach 1:
The patent combines multiple electrode groups with different orientations (X-direction and Y-direction diamond-shaped electrodes) into a unified detection system. By merging the detection outputs from both electrode groups, the system amplifies the overall capacitance change signal, making gloved touches reliably detectable without requiring excessive density in any single electrode pattern, thus balancing reliability with manufacturability.
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
The solution significantly improves detection sensitivity and accuracy, reducing false detection caused by non-human objects like water droplets, and maintains high directivity, effectively addressing the limitations of existing capacitive touch sensors.
Implementation Method 1
a capacitive touch sensor employs a resistive film method, an electrostatic method, an optical detection method, or the like. The touch sensor employing the electrostatic method, that is, a capacitive touch sensor, detects a change of an electrostatic capacitance obtained when a conductive body or a portion of a human body is close to a conductive substance
Implementation Method 2
detects a change of an electrostatic capacitance obtained when a conductive body or a portion of a human body is close to a conductive substance and inputs operation information by detecting a position of the conductive body or the portion of the human body
Data Source
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AI summary
An electrostatic sensor which detects a position of an object to be detected which is approaching the electrostatic sensor, includes a first electrode group including a plurality of electrodes, a second electrode group including a plurality of electrodes which are adjacent to the electrodes of the first electrode group, detection circuits configured to be individually connected to electrodes selected from among the electrodes of the first electrode group and the electrodes of the second electrode group and have respective first alternating-current sources and respective current measurement units, a second alternating-current source configured to be connected to unselected electrodes among the electrodes of the first electrode group and the electrodes of the second electrode group, and a controller. Alternating voltage generated by the first alternating-current sources and alternating voltage generated by the second alternating-current source have the same frequency and the same phase. The controller successively selects electrodes to be connected to the detection circuits from among the electrodes of the first electrode group and the electrodes of the second electrode group, causes the selected electrodes to be connected to the detection circuits, and detects a position of the object to be detected based on current detected by current measurement units included in the detection circuits.