Spring-Loaded Chronograph Zero Reset for Reliable Single-Press Operation

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Solution Overview

Problem

Existing zero-setting devices for chronographs require multiple components, leading to high manufacturing costs and maintenance efforts, and often necessitate multiple presses to reliably reset counter hands to the zero position due to insufficient user force.

Innovation Solution

A zero-setting device utilizing a first compression spring connected to a zero-setting lever arm, which indirectly interacts with the control means to transmit force for reliable zero-setting with reduced components, allowing single-press operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a return spring is used to hold the zero-setting lever in a free position, then the lever can be reset to zero position, but the user force is insufficient to reliably rotate the cams and reset the hands

Engineering Contradiction:
Improvereliability of hand resetVSAvoiduser force requirement
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent applies preliminary action by pre-loading a first compression spring in a first deflected state before the reset operation. This stored elastic energy is then released to provide the additional force needed to reliably rotate the zero-setting cam and reset the chronograph hand, eliminating the insufficiency of user-applied force while maintaining ease of operation.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If multiple zero-setting cams and hammers are used to reset multiple counter hands, then each hand can be reset to zero position, but the device complexity and number of components increase significantly

Engineering Contradiction:
Improvehand reset functionalityVSAvoidnumber of components
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent applies universality by designing a single zero-setting lever that can reset multiple counter hands (seconds and minutes) through a single cam mechanism. This multi-functional approach eliminates the need for separate hammers and cams for each hand, significantly reducing device complexity while maintaining full reset functionality for all chronograph counters.

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

Solution Approach 2:

The patent merges multiple reset functions into a single integrated mechanism. The zero-setting lever combines the functions of multiple hammers, and the single zero-setting cam replaces multiple cams, thereby reducing the number of components and simplifying the overall device structure while preserving the ability to reset multiple hands.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If multiple individual hammer springs are used to preload each hammer, then the impulse to zero-setting cams is increased, but the operating force required increases and the device becomes more complex

Engineering Contradiction:
Improveimpulse to zero-setting camsVSAvoidoperating force
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent combines multiple individual hammer springs into a single first compression spring. This unified spring provides the necessary pre-load and impulse to the zero-setting cam through the zero-setting lever, maintaining reliable hand reset functionality while reducing the number of components and lowering the operating force required compared to multiple separate springs.

Inventive Principle:
Principle #5Merging (Combining)

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

Reduces manufacturing costs and maintenance requirements while ensuring durable and user-friendly resetting of counter hands to the zero position with improved reliability.

Implementation Method 1

a first compression spring (140) which is supported on the zero-setting lever arm (210) and is in a first deflected state, in particular in a pre-loaded state

Methodology Applied
Scientific EffectElastic energy storage and release: Spring

Data Source

PatentEP4372489B1Spring loaded zero reset mechanism
Publication Date: 2025.07.30 DAMASKO PRÄZISIONSTECHNIK GMBH & CO KG
  • EP4372489B1 patent drawingFigure 1
  • EP4372489B1 patent drawingFigure 2
  • EP4372489B1 patent drawingFigure 3

AI summary

The invention relates to a zeroing device 100 for a chronograph movement 300, comprising at least one zeroing heart 110, 120, a zeroing unit 200 having a zeroing lever arm 210 and a zeroing lever latch 220, the first end 221 of which is designed to abut the at least one zeroing heart 110, 120, and a control means 130 cooperating with the zeroing lever arm 210, wherein the zeroing unit 200 is set to zero by actuating the control means 130. The object of the present invention is to provide a zeroing device 100 for a chronograph that enables cost-effective manufacturing and low maintenance while simultaneously ensuring a reliable, durable, and user-friendly reset of the counter hands to the zero position.The problem is solved by the zeroing device 100 comprising a first compression spring 140 which is supported on the zeroing lever arm 210 and is operatively connected to the control means 130, and the control means 130 interacting indirectly with the zeroing unit 200 via the first compression spring 140.