Push-button Switch Lever Mechanism for Large Surface Actuation

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Solution Overview

Problem

Existing pushbutton switches struggle to provide consistent actuation forces and haptic feedback on large surfaces, often requiring multiple sensors and being unsuitable for heavy or large elements like 5-inch displays, which can lead to tilting and unreliable triggering.

Innovation Solution

A pushbutton switch design featuring a simple, robust mechanism with two levers mounted play-free on a base plate, using a central switching element for haptic feedback, and a display on the key cap, allowing for a flat and stable surface with parallel displacement, suitable for large areas and various applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a large-area touch switch is designed to support heavy elements like displays, then the structural strength and stability are improved, but the device complexity and number of required sensors increase

Engineering Contradiction:
Improvestructural strengthVSAvoiddevice complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The pushbutton switch is divided into functionally independent segments: a key cap for user input, a base plate for structural support, and a single central switching element for detection. This segmentation allows each component to be optimized independently, achieving high strength and stability without increasing overall system complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The single switching element serves multiple functions: detecting actuation force, providing haptic feedback through its mechanical response, and triggering the switch signal. This multi-functionality eliminates the need for multiple sensors while maintaining reliability across large surface areas.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If multiple sensors are used to ensure reliable activation across large surfaces, then the measurement precision and reliability are improved, but the device complexity and cost increase

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Multiple sensing functions are merged into a single central switching element. The lever mechanism transmits force from any position on the key cap to this central element, which then handles detection, feedback, and signal generation. This consolidation maintains reliability while dramatically reducing complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The lever mechanism acts as an intermediary that distributes and concentrates force from the large key cap surface area to the single central switching element. This mechanical mediation ensures that actuation force from any location on the key cap is reliably transmitted to trigger the switch.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If the key cap is designed with a long guide in the direction of actuation to provide tactile feedback, then the haptic feedback quality is improved, but the overall height and device complexity increase

Engineering Contradiction:
Improvehaptic feedbackVSAvoidoverall height
Core Design Contradiction:
Ease of operationVSLength of stationary object

Solution Approach 1:

The lever mechanism provides dynamic haptic feedback through its mechanical properties. As the key cap is pressed, the levers rotate and compress the switching element, creating natural tactile resistance and a satisfying click. This dynamic mechanical response eliminates the need for long guides while maintaining excellent haptic feedback.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent replaces the traditional mechanical guide system with a lever-based mechanism. Instead of relying on the length of a guide to provide tactile feedback, the system uses the rotational movement and elastic properties of the levers to create haptic response, significantly reducing the required height.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Ease of manufacture

If the levers are mounted with play on the base plate to allow movement, then the ease of assembly is improved, but the manufacturing precision and positioning accuracy deteriorate

Engineering Contradiction:
Improveease of assemblyVSAvoidpositioning accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The mounting design implements local quality by providing play-free mounting at the pivot points where precision is critical, while allowing controlled movement in the actuation direction. This selective approach ensures high positioning accuracy where needed without compromising ease of assembly.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent uses identical lever designs with standardized mounting features that can be replicated. This copying approach allows for precise, consistent positioning across multiple units while maintaining ease of assembly through standardization.

Inventive Principle:
Principle #26Copying

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 ensures consistent haptic feedback and reliable actuation across large surfaces with a single central switching element, preventing twisting and allowing for easy assembly and adaptation to different applications, making it suitable for vehicles and other applications requiring thin keys and touchscreens.

Implementation Method 1

The switching element is a piezoelectric switch arranged such that it generates the switching signal when the actuating element is inserted into the housing

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a first lever (5) and a second lever (6) which are rotatably mounted on a base plate (3) in a lever-like manner

Methodology Applied
Scientific EffectLever mechanism: Lever

Data Source

PatentEP3486931B1Push-button switch and motor vehicle with push button switch
Publication Date: 2020.12.09 VOLKSWAGEN AG
  • EP3486931B1 patent drawingFigure 1~2
  • EP3486931B1 patent drawingFigure 3~4
  • EP3486931B1 patent drawingFigure 5~6

AI summary

A push-button switch and a motor vehicle in which such a push-button switch is used. The push-button switch (1) has a keycap (2), a base plate (3), a switching element (4), a first lever (5), and a second lever (6). The first lever (5) and the second lever (6) are each rotatably mounted on the base plate (3) by means of a pivot bearing (7) and are each movably connected to the keycap (2) at a first lever end (8). At a second lever end (9), the first lever (5) and the second lever (6) are movably connected to each other. The switching element (4) is arranged on the keycap (2) such that it can be actuated by the second lever end (9) of the first lever (5) or by the second lever end (9) of the second lever (6).