Capacitive Input Device Dual Detection Mode Switching
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Solution Overview
Problem
Existing capacitive input devices face challenges in accurately detecting positional information and pressing force with certainty due to changes in contact area and capacitance, especially when the operating body approaches without touching the panel, and difficulties in distinguishing between position detection and force detection.
Innovation Solution
A capacitive input device with facing electrode pairs on two substrates, where a switching unit allows for two detection states: one for detecting pressing force and another for positional information, using the same electrode pairs connected to a driving or detecting unit, enabling sensitive and accurate detection without increasing substrate spacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the spacing between upper and lower conductive films is increased to reduce capacitance, then the change in capacitance when pressing force is applied becomes more detectable, but the detection sensitivity for pressing force decreases
Solution Approach 1:
The patent divides the electrode structure into multiple independent electrode groups (first electrode group and second electrode group) arranged in matrix patterns on upper and lower substrates. Each electrode can be independently controlled and detected, allowing the system to distinguish between position changes and pressing force effects by analyzing capacitance changes in specific electrode pairs rather than relying solely on the overall capacitance between substrates.
Solution Approach 2:
The patent implements dynamic switching between two detection modes through a switching unit: a first detection mode for positional information and a second detection mode for pressing force. This allows the system to adaptively select the appropriate detection strategy based on the operational requirement, optimizing both position detection accuracy and pressing force detection sensitivity without compromise.
2Measurement precision
If electrode groups are arranged in matrix patterns to detect positional information, then the resolution of position detection improves, but the complexity of the electrode structure increases
Solution Approach 1:
The patent designs electrode groups that serve multiple functions: the same matrix-arranged electrode groups used for high-resolution position detection also function as sensing elements for pressing force detection when operated in the second detection mode. This multi-functionality reduces the need for separate specialized electrode structures, thereby managing complexity while maintaining high performance in both detection capabilities.
3Device complexity
If the same electrode pairs are used for both position and force detection, then the device complexity is reduced, but the detection reliability for distinguishing between position and force changes deteriorates
Solution Approach 1:
The patent employs a switching unit that dynamically reconfigures the electrical connections to electrode pairs based on the required detection mode. In the first detection mode, electrode pairs are connected to detect positional information, while in the second detection mode, the same physical electrode pairs are reconnected to detect pressing force. This dynamic reconfiguration allows the system to maintain simple electrode physics while achieving reliable mode distinction through controlled electrical switching rather than physical complexity.
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 positional information and pressing force with reduced power consumption and stable detection processing, maintaining constant capacitance when no operation is performed.
Implementation Method 1
a capacitance is formed between an electrode in the electrode group A and an electrode in the electrode group B. When an operating body touches or approaches a detecting electrode, coupling is formed between the capacitance formed between an electrode in the electrode group A and an electrode in the electrode group B and a capacitance formed between each electrode and the operating body, and positional information of the operating body is acquired in accordance with the change in the coupled capacitance.
Implementation Method 2
the input device according to Japanese Unexamined Patent Application Publication No. 2008-140130 is considered to be able to detect whether a pressing force is applied to the top panel in accordance with a change in the capacitance between the electrodes on the upper conductive film and the ground. This is because the upper and lower conductive films move closer to each other in response to the pressing force applied to the top panel.
Data Source
AI summary
First and second substrates are disposed to face each other and allowed to approach each other. A plurality of first electrodes are formed on the first substrate. A plurality of second electrodes are formed on the second substrate and face the respective first electrodes. A facing electrode pair is constituted by each of the first electrodes and a corresponding one of the second electrodes. A switching unit causes each of the first electrodes and each of the second electrodes to be connected to a driving unit or a detecting unit and switches between a first detection state in which a distance change between each of the first electrodes and a corresponding one of the second electrodes is detected and a second detection state in which the coordinates of a position that an operating body approaches or touches are determined in accordance with detection outputs from the facing electrode pairs.