Multi-Character Keycaps with Segmented Supports
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Solution Overview
Problem
Modern keypad and keyboard designs in handheld electronic devices face challenges in providing stable, illuminated, and tactilely distinct keys within a thin profile, often resulting in wobbly and prone-to-damage keys due to the use of dome switches.
Innovation Solution
A key assembly featuring multi-character keycaps with external contact portions and keycap supports that inhibit unintended key actuations, combined with an actuator sheet and dome switches, provides stability and tactile feedback while allowing for preloading of dome switches to reduce actuation force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If dome switches are used to provide a thinner device profile, then device thickness is reduced, but key stability and durability deteriorate
Solution Approach 1:
The keycap is divided into multiple segments (first keycap portion, second keycap portion, third keycap portion) that can move independently. This segmentation allows each portion to provide tactile feedback for its associated dome switch while the overall keycap structure remains thin. The segmented design prevents the entire keycap from becoming wobbly, as each segment is stabilized by its corresponding dome switch mechanism.
Solution Approach 2:
Different portions of the keycap have different functional properties. The first keycap portion is associated with a first dome switch, the second portion with a second dome switch, and so on. Each local region of the keycap is optimized for its specific function, allowing the thin profile to be maintained while providing stable, responsive keys through localized dome switch-keycap portion pairings.
2Device complexity
If multiple characters are integrated into single keycaps, then device complexity is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The multi-character keycap is segmented into distinct portions (first, second, third keycap portions), each associated with a specific dome switch. This segmentation simplifies the manufacturing process by allowing each portion to be positioned and aligned with its corresponding switch independently, rather than requiring precise positioning of all characters simultaneously. The segmented structure reduces the overall manufacturing precision burden while maintaining the multi-character functionality.
3Reliability
If keycap supports are added to prevent multi-touch, then manufacturing complexity increases, but key reliability improves
Solution Approach 1:
Keycap support structures are introduced as intermediary elements between the keycap portions and the dome switches. These supports prevent unintended multi-touch by providing mechanical guidance and limiting the movement of keycap portions to their intended actuation paths. The intermediaries stabilize the keycaps during actuation, ensuring that only the intended dome switch is activated while preventing adjacent switches from being accidentally triggered.
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 enhances key stability and tactile feedback, reduces the force required for key presses, and prevents accidental key activations, resulting in a more durable and user-friendly keypad design.
Implementation Method 1
the use of dome switches may result in keys which are wobbly and unstable... provides stability and tactile feedback while allowing for preloading of dome switches to reduce actuation force
Data Source
AI summary
According to one aspect, a keypad for an electronic device includes a plurality of switches and a plurality of keycaps. Each keycap has a plurality of external contact portions defining a full row of the keypad. Each external contact portion corresponds to one of the switches and includes at least one of a text-entry character and a functional character. Each of the external contact portions is movable to actuate the corresponding switch. The keypad further includes a plurality of keycap supports. Each keycap support is disposed between adjacent external contact portions. After one of the external contact portions has been moved to actuate the corresponding switch, at least one of the keycap supports engages the keycap having the one of the external contact portions to inhibit the keycap from actuating at least one of the other switches.