Stepped Key Input Structure for Ergonomic and Quiet Typing

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional key input devices do not effectively accommodate the ergonomic needs of users, leading to fatigue and inconsistent key operability and sound feedback.

Innovation Solution

A key input device with sloped key tops and a top casing design featuring parallel surfaces with stepwise height changes and nonwoven fabric sheets to absorb keystroke sounds, ensuring uniform operability and reduced fatigue.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If key tops are arranged on a flat surface, then manufacturing is simple, but user comfort deteriorates due to fatigue from inconsistent key heights

Engineering Contradiction:
Improveuser comfortVSAvoidcasing structure
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The top casing transitions from a flat two-dimensional surface to a three-dimensional sloped surface. The casing includes a sloping panel part that inclines from the front toward the back, creating varying key heights that conform to hand contours. This dimensional change allows keys at different positions to be at different heights, improving ergonomic comfort while maintaining a relatively simple single-piece casing structure.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Ease of operation

If key heights vary to fit hand contours, then ease of operation improves, but manufacturing precision requirements increase

Engineering Contradiction:
Improvekey operability uniformityVSAvoidsloped surface accuracy
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent applies a consistent inclination angle parameter to the sloping panel part. By defining the slope as a uniform angular parameter rather than varying heights for each key, the manufacturing process becomes more controllable. The sloped surface is formed as a continuous geometric progression, ensuring that key height differences are predictable and consistent, thereby improving manufacturing precision while maintaining ergonomic benefits.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If keys are arranged on an inclined surface, then ergonomic comfort improves, but device volume increases

Engineering Contradiction:
Improvehand fitVSAvoidcasing volume
Core Design Contradiction:
Ease of operationVSVolume of moving object

Solution Approach 1:

The top casing is segmented into distinct functional zones: a front flat panel part for display or additional controls, and a back sloping panel part for the main keyboard. This segmentation allows the inclined ergonomic surface to be applied only where needed (under the keys), rather than throughout the entire device. The sloped portion is confined to the keyboard area, minimizing the overall volume increase while maintaining ergonomic benefits for key operation.

Inventive Principle:
Principle #1Segmentation

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 design enhances user comfort by fitting key heights to hand contours and reduces keystroke noise, providing uniform operability and sound absorption.

Implementation Method 1

nonwoven fabric sheets to absorb keystroke sounds

Methodology Applied
Scientific EffectAcoustic absorption: Acoustic Absorption

Data Source

PatentEP4528422A1Key input device
Publication Date: 2025.03.26 CASIO COMPUTER CO LTD
  • EP4528422A1 patent drawingFigure 1
  • EP4528422A1 patent drawingFigure 2
  • EP4528422A1 patent drawingFigure 3

AI summary

A key input device (1) includes keys (14) and a member (10) having surfaces (102A, 102B, 102C, 102D, 102E) parallel to each other, the surfaces each having at least one first through hole (101) among first through holes (101). The keys are inserted to the corresponding first through holes. The member has a first end side, a second end side, a third end side, and a fourth end side, the first end side being opposite the second end side, the third end side being perpendicular to the first end side and opposite the fourth end side. The surfaces of the member are flat from the first end side toward the second end side. The member has a step between a surface on the third end side and a surface on the fourth end side among the surfaces.