Butterfly Hinge Key Mechanism for Low-Profile Tactile Input
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Solution Overview
Problem
Existing electronic devices, such as keyboards, face challenges in minimizing size and manufacturing costs due to the large space occupied by input devices, which can be alleviated by reducing the z-stackup of key mechanisms.
Innovation Solution
The implementation of a butterfly hinge-based key mechanism that allows for low travel distances with a desired tactile response, utilizing a double wing design and pivot pins to minimize keystroke depth while maintaining consistent tactile feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If traditional key mechanisms are used, then tactile response is achieved, but z-stackup height is large
Solution Approach 1:
The key mechanism is divided into separate functional components: a scissor mechanism for vertical motion, a butterfly hinge for rotational motion, and a dome switch for actuation. This segmentation allows each component to be optimized independently, achieving low profile height while maintaining tactile feedback through the specialized dome switch component.
Solution Approach 2:
The mechanism transitions from purely vertical motion to a combination of vertical and rotational motion. The butterfly hinge introduces rotational movement as an additional dimension, allowing the keycap to pivot while descending, thereby reducing the vertical travel distance needed to achieve the same actuation effect.
2Volume of moving object
If key mechanism size is reduced, then device size is minimized, but manufacturing complexity increases
Solution Approach 1:
Multiple functions are merged into integrated components. The scissor mechanism and butterfly hinge are combined into a single assembly that works together to achieve both compact size and low profile. The dome switch serves multiple purposes: providing tactile feedback, actuating the switch, and defining the key travel distance, thereby reducing the need for separate components.
Solution Approach 2:
The butterfly hinge serves multiple functions: it enables rotational motion, provides structural support, and works in conjunction with the scissor mechanism to achieve the low profile configuration. This multi-functionality reduces the total number of components needed, simplifying manufacturing despite the reduced size.
3Length of moving object
If keystroke distance is reduced, then device thickness is minimized, but tactile feedback consistency becomes difficult to maintain
Solution Approach 1:
The mechanism changes the motion parameters from pure vertical translation to a combination of vertical and rotational motion. The butterfly hinge introduces a rotational component that allows the keycap to pivot during actuation, maintaining tactile feedback through the angular movement while reducing the vertical travel distance required to actuate the dome switch.
Solution Approach 2:
The butterfly hinge acts as an intermediary between the keycap and the dome switch. It translates the user's pressing motion into a controlled rotational and vertical movement that consistently actuates the dome switch at the correct point, ensuring uniform tactile feedback across all keys regardless of variations in pressing force or angle.
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 the creation of thinner keyboards with uniform tactile response across the keycap surface, reducing keystroke distance to between 0.1 mm to 2.0 mm, and maintaining stability and tactile feel over the device's lifetime.
Implementation Method 1
each wing is operative to pivot about its own pivot axis during a keystroke of the key mechanism
Implementation Method 2
a dome switch is secured within the cavity between the keycap assembly and the support structure, the dome switch operative to bias the keycap assembly in a first position
Data Source
AI summary
A key mechanism including one or more butterfly hinges. Each butterfly hinge may include a double wing design operative to move between a depressed position and non-depressed position. Hinged coupling mechanisms couple respective arms of the wings together. Additionally or alternatively, a key mechanism can include one or more half-butterfly hinges. Each half-butterfly hinge includes a double wing design operative to move between a depressed position and non-depressed position. A hinged coupling mechanism couples one set of corresponding arms of the wings together, while the other set of corresponding arms are not coupled together.