Pushbutton Switch Member With Segmented Dome And Rubber Actuator
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Solution Overview
Problem
Conventional pushbutton switch members face challenges in achieving a high load capacity, long stroke, and strong click feeling due to issues with positional differences between the pusher and metal dome, adhesive variations affecting dimensional tolerance, and reduced durability from increased sheet thickness or curvature.
Innovation Solution
The pushbutton switch member incorporates a dome-shaped movable contact with an outer extension part and an operation key having a foot part fixed on the substrate, with a fixation sheet covering the outer extension part to enhance adhesion and maintain a long stroke while ensuring a strong click feeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the metal dome is pushed alone, then the structure is simple, but the stroke until peak load is short and high load capacity cannot be achieved
Solution Approach 1:
The pushbutton switch member is divided into two functional parts: a rubber switch for initial pushing and a metal dome for final switch actuation. This segmentation allows each component to be optimized for its specific function, with the rubber providing a long, comfortable stroke and the metal dome providing the precise click feeling and high load capacity needed for switch actuation.
Solution Approach 2:
The invention combines a rubber switch and a metal dome into a single integrated pushbutton switch member. The rubber switch and metal dome work together in sequence, with the rubber deforming first and then transferring force to the metal dome, which deforms to actuate the switch. This merging allows the system to achieve both long stroke and high load capacity.
2Force
If the sheet thickness or curvature of the metal dome is increased to achieve high load capacity, then the load handling ability improves, but durability against repetitive deformation decreases and size increases
Solution Approach 1:
The load-bearing function is segmented between the rubber switch and the metal dome. The rubber switch handles the initial pushing and absorbs much of the deformation, while the metal dome handles the final precise actuation. This allows the metal dome to be thinner and more durable since it doesn't need to handle the full load alone throughout the entire stroke.
Solution Approach 2:
The invention changes the material parameter from using a thick metal dome to using a thinner metal dome combined with a rubber switch. The rubber material allows for greater elasticity and repetitive deformation without permanent damage, while the thinner metal dome provides sufficient stiffness for the final actuation phase.
3Force
If a rubber switch is disposed above the metal dome to reduce load issues, then load capacity improves, but positional difference between pusher and metal dome occurs degrading touch feeling
Solution Approach 1:
The rubber switch and metal dome are merged into a single integrated component where the rubber is formed directly connected to the metal dome. This integration eliminates the need for separate positioning mechanisms and adhesive agents, ensuring precise positional alignment between the pusher and metal dome while maintaining the load-bearing advantages of the rubber switch.
Solution Approach 2:
The rubber switch acts as an intermediary between the user's finger and the metal dome. It provides a large, comfortable pushing surface and gradually transfers force to the metal dome, ensuring that the pusher position and metal dome position remain aligned throughout the deformation process, thus maintaining excellent touch feeling.
4Manufacturing precision
If adhesive agent is used to fix the pusher to the metal dome to eliminate positional difference, then positioning accuracy improves, but dimensional tolerance increases and click feeling is reduced
Solution Approach 1:
The rubber material serves as an intermediary connection between the pusher and metal dome, replacing the adhesive agent. The rubber's elasticity and conformability allow it to bond effectively to the metal dome surface while accommodating dimensional variations, eliminating the need for precision adhesive application and ensuring consistent positional alignment without compromising the metal dome's click feeling.
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 allows for a high load capacity, reliable long stroke, and improved adhesion force between the dome-shaped movable contact and the key, enhancing the overall switch feeling and durability.
Implementation Method 1
a fixation sheet covering at least a portion of a surface of the outer extension part and fixing at least a portion of the outer extension part to the foot part
Implementation Method 2
a switch is turned on through deformation of a metal dome when pushing is externally applied on a central top part of the metal dome
Data Source
Figure 1(A)~1(B)
Figure 2(A)~2(B)
Figure 3
AI summary
[Problem] To provide a pushbutton switch member which is compact and able to handle a high load, and which easily delivers a feeling of full stroke and strong click. [Solution] The present invention pertains to a pushbutton switch member 30 provided with a dome-shaped movable contact 20 and an operation key 10, positioned facing and separate from the protrusion side of the movable contact 20. Pushing the operation key 10 in the direction of the movable contact 20 causes the movable contact 20 to electrically connect at least two contacts 41, 42 on a substrate 40. The operation key 10 is provided with: a key body 11; a dome part 12 connected with an outer periphery of the key body 11, and deformable by pushing of the key body 11 toward the substrate 40; and a foot part 14 connected with an outer periphery of the dome part 12, and fixed on the substrate 40. The movable contact 20 is provided with: an upper contact part 21 spaced apart from a site directly below the key body 11, and which makes contact with a contact 42 when the key body 11 is pushed in; and an outer fixing part 25 disposed at the upper contact part 21, or further outside thereof in the radial direction, and fixed outside of the key body 11 in the radial direction.