Touch Sensing Coil Layout for Metal-Frame Switch Integration
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Solution Overview
Problem
Conventional touch switch devices face challenges with design neatness due to mechanical switch requirements, risk of electric shock, and limited freedom in placing the sensing coil, as well as difficulties in distinguishing multiple touch switches in a metal case, leading to potential misoperation.
Innovation Solution
A touch sensing device is designed with a non-conductive cover and conductive frame, featuring a sensing electrode and coil configuration that allows for flexible placement and integration within an electronic device, using a shielding material to prevent parasitic capacitance and enhance safety, and a circuit unit to detect touch and force inputs through resonant frequency changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical switch is used to replace a mechanical switch, then the switch function is implemented, but the design neatness deteriorates due to protruding form and lack of integration with external case
Solution Approach 1:
The patent replaces the mechanical switch system with a touch sensing system comprising a sensing electrode, sensing coil, and circuit unit. The mechanical pressing action is substituted by capacitive touch detection and inductive sensing, eliminating the need for mechanical components while maintaining the switch function. This substitution resolves the contradiction by providing a flush-mounted, integrated design that preserves design neatness while ensuring reliable touch detection.
Solution Approach 2:
The touch sensing device performs multiple functions: it detects touch input through the sensing electrode, detects pressing force through the sensing coil's inductance change, and provides both capacitive and inductive sensing capabilities. This multi-functionality allows the system to replace mechanical switches while maintaining reliable input detection and improving design integration.
2Reliability
If a mechanical switch is used, then the switch function is implemented, but the device complexity increases due to large internal space requirements
Solution Approach 1:
The mechanical switch structure with its moving parts, actuation mechanisms, and required clearance spaces is replaced by a planar sensing electrode and a compact sensing coil. The sensing electrode can be fabricated as a thin conductive layer, and the sensing coil can be implemented as a compact inductor structure. This substitution dramatically reduces the internal space required while maintaining the switch function through electromagnetic and capacitive sensing.
Solution Approach 2:
The patent uses a sensing electrode that can be fabricated as a printed or patterned conductive layer on a substrate, copying the switch function through electromagnetic field interaction rather than mechanical contact. This approach allows the switch function to be implemented with minimal internal space, as the sensing elements can be integrated into the device's existing structure layers.
3Reliability
If a mechanical switch is used, then the switch function is implemented, but dustproofing and waterproofing deteriorate due to the structure of the mechanical switch
Solution Approach 1:
The mechanical switch with its physical openings, moving parts, and sealing requirements is replaced by a sealed touch sensing structure. The sensing electrode and sensing coil are enclosed within the device housing, with only the touch surface exposed. This eliminates the need for mechanical seals and moving parts that could compromise dustproofing and waterproofing, while maintaining reliable touch and force detection through electromagnetic and capacitive sensing.
Solution Approach 2:
The touch sensing device provides both touch detection and force sensing capabilities through the same sealed structure. The sensing electrode detects capacitive changes from touch, while the sensing coil detects inductance changes from pressing force. This multi-functionality is achieved within a single sealed enclosure, maintaining both switch function and environmental protection without requiring separate mechanical components.
4Reliability
If multiple touch switches are disposed in a metal case, then the switch function is implemented, but the ease of operation deteriorates due to difficulty in distinguishing and recognizing each position
Solution Approach 1:
The patent employs visual differentiation methods such as color coding, pattern variations, or illumination differences on the touch switch surfaces. These visual cues allow users to easily distinguish between multiple touch switches in a metal case, preventing misoperation while maintaining the sleek integrated design. The visual differentiation is applied to the touch-sensitive surfaces without compromising the metal case's aesthetic or the sensing functionality.
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 provides a safe, compact, and efficient touch and force sensing system that prevents misoperation by allowing flexible coil placement, improving design aesthetics, and ensuring accurate touch detection without the risks associated with mechanical switches.
Implementation Method 1
a first oscillation circuit configured to generate a first oscillation signal having a resonant frequency that changes in response to the first touch member being touched
Implementation Method 2
the first touch sensing unit having a capacitance that changes in response to a human body touching the first touch member according to a parasitic capacitance generated between the first sensing electrode, the first touch member, and the human body
Data Source
AI summary
A touch sensing device configured to be installed in an electronic device, the electronic device including a side unit and a touch switch unit, the side unit including a non-conductive cover and a conductive frame coupled to the cover, the touch switch unit including a first touch member that is a portion of the cover, the touch sensing device including a first sensing electrode configured to be disposed inside the electronic device near the first touch member; a first sensing coil configured to be disposed inside the electronic device; and a first connection wire including one end connected to the first sensing electrode and another end connected to the first sensing coil, thereby electrically connecting the first sensing electrode to the first sensing coil.