Pushbutton Plate Spring Layout for Impact-Resistant Timepiece Switches

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Solution Overview

Problem

Existing electronic timepieces face challenges in impact resistance, as sudden pushes from external impacts, such as falls, can unintentionally activate the pushbutton switch, potentially damaging the internal structure and disrupting operation.

Innovation Solution

The design incorporates a first plate spring and a second plate spring that extends beyond the tip of the first spring in a perpendicular direction, allowing the second spring to contact an electrode when the pushbutton switch is pushed, dispersing impact and maintaining contact without unnecessary lengthening of the spring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the plate spring is lengthened to reduce impact transmission, then impact resistance improves, but the spring cannot be lengthened unlimitedly due to space constraints

Engineering Contradiction:
Improveimpact resistanceVSAvoidplate spring length
Core Design Contradiction:
ReliabilityVSLength of moving object

Solution Approach 1:

The patent transitions from a single linear spring configuration to a two-dimensional L-shaped configuration. The first plate spring extends in a first direction, and the second plate spring extends in a second direction perpendicular to the first direction, allowing the spring to occupy space in multiple dimensions rather than just one, thereby achieving longer effective length within limited space

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

Solution Approach 2:

The patent divides the plate spring into two separate components: a first plate spring and a second plate spring. These segmented springs work together to provide the full length needed for impact absorption while fitting within the space constraints of the electronic timepiece housing

Inventive Principle:
Principle #1Segmentation

2Volume of moving object

If the plate spring is made shorter to fit within space constraints, then device compactness improves, but impact absorption capability deteriorates

Engineering Contradiction:
Improvespring assembly volumeVSAvoidimpact absorption
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

By configuring the springs in an L-shape with perpendicular orientations, the design utilizes three-dimensional space more efficiently. The first plate spring extends in a first direction and the second plate spring extends in a second direction perpendicular to the first direction, achieving long impact absorption path within compact volume

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

Solution Approach 2:

The two plate springs are arranged in a nested-like configuration where the second plate spring branches off from the first plate spring. This nested arrangement allows both springs to be integrated within a compact space while maintaining their individual lengths for effective impact absorption

Inventive Principle:
Principle #7Nested doll (Nesting)

3Measurement precision

If the pushbutton switch is made sensitive to detect pushes, then detection precision improves, but susceptibility to unintentional activation by impact increases

Engineering Contradiction:
Improvepush detection precisionVSAvoidunintentional activation by impact
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The detection mechanism is segmented into two separate plate springs with different functions. The first plate spring is optimized for detection sensitivity, while the second plate spring provides impact absorption. This segmentation allows the detection element to be sensitive without being directly exposed to full impact forces

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The second plate spring acts as an intermediary between the external impact and the first plate spring. It absorbs and reduces impact forces before they reach the detection mechanism, protecting the sensitive detection element from unintentional activation while allowing normal push operations to be detected

Inventive Principle:
Principle #24Intermediary (Mediator)

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 enhances the impact resistance of electronic devices by absorbing and dispersing forces, reducing the risk of damage and malfunction, while maintaining efficient detection of pushbutton switch operations.

Implementation Method 1

the shaft of a pushbutton switch pushes and deforms a conductive plate spring when the pushbutton switch is pushed

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

the plate spring lessens such an impact

Methodology Applied
Scientific EffectImpact absorption: Damping

Data Source

PatentEP4332692A1Electronic device and electronic timepiece
Publication Date: 2024.03.06 CASIO COMPUTER CO LTD
  • EP4332692A1 patent drawingFigure 1
  • EP4332692A1 patent drawingFigure 2
  • EP4332692A1 patent drawingFigure 3

AI summary

An electronic device (100) includes a first plate spring (1431), a second plate spring (1432) and a substrate (11). The first plate spring (1431) extends in a first direction from a fixed end (141). The second plate spring (1432) branches off from the first plate spring (1431) and extends in the first direction beyond a tip of the first plate spring (1431) in the first direction. The substrate (11) has an electrode (11c) that contacts the second plate spring (1432) accompanied by the first plate spring (1431) being pushed by a pushbutton switch being pushed. The substrate (11) does not contact the first plate spring (1431). The second plate spring (1432) has a tip part. In a plan view in a push direction of the switch, the tip part extends, at a point beyond the tip of the first plate spring (1431), in a second direction different from the first direction to overlap the substrate (11). The tip part contacts the electrode (11c) by the switch being pushed.