Layered Watch Dial for Optical Hand Position Detection

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Solution Overview

Problem

Existing electromechanical watches are prone to inaccuracies in displaying time due to external disturbances, necessitating a solution to autonomously and accurately determine the position of the hour and minute hands.

Innovation Solution

A watch dial with an autonomous determination device comprising light sources, a photovoltaic module, a light-detecting element, and a control unit, integrated in thin layers, which measures the position of the hands using reflected light beams and generates visual messages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electromechanical watch hands are driven by gear trains, then the watch can display time mechanically, but the hand position becomes inaccurate due to external disturbances and impacts

Engineering Contradiction:

Improvehand position accuracyVSAvoidexternal disturbances

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical gear train system with an autonomous optical detection system. Light sources emit beams that reflect off the hands, and light-detecting elements measure the reflected light to determine hand positions electronically, eliminating mechanical transmission errors caused by external disturbances

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The determination device is fully autonomous, using its own integrated light sources and photovoltaic module to detect hand positions without requiring external power or control from the mechanical movement, making the system self-sufficient and immune to mechanical disturbances

Inventive Principle:

Principle #25Self-service

2Measurement precision

If an autonomous determination device is added to the dial, then hand position can be accurately determined, but the device complexity increases

Engineering Contradiction:

Improvehand position measurementVSAvoiddial structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the determination device components directly into the dial structure itself. The light sources, light-detecting elements, photovoltaic module, and control unit are all integrated within the dial layers, combining the functions of time display and position measurement in a single unified structure

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent implements the determination device in a two-dimensional planar layout within the dial layers rather than using three-dimensional mechanical components. The light sources and detectors are arranged in specific patterns on the dial surface, enabling position measurement through optical paths in the plane of the dial

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Extent of automation

If light sources and detecting elements are integrated in the dial, then the determination device becomes autonomous, but the manufacturing complexity increases

Engineering Contradiction:

Improvedetermination device autonomyVSAvoiddial assembly

Core Design Contradiction:

Extent of automationVSEase of manufacture

Solution Approach 1:

The patent divides the determination device into distinct functional layers within the dial structure. Each layer contains specific components (light sources in one layer, detectors in another, photovoltaic module in a third), allowing independent manufacturing and assembly of each layer before final integration

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dial structure serves multiple functions simultaneously: it displays time visually, houses the autonomous determination device, provides structural support, and facilitates light transmission. This multi-functionality reduces the need for separate components and simplifies the overall manufacturing process

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 provides constant and accurate hand position determination, independent of the watch's power source, enabling precise timekeeping and additional functions like resynchronization and illumination.

Implementation Method 1

a stand-alone power supply unit comprising a photovoltaic module

Methodology Applied

Scientific EffectPhotovoltaic effect: Photovoltaic Effect

Implementation Method 2

a first light source and at least a second light source... arranged so that a light beam emitted by said at least one first light source is reflected by said at least one hand towards said at least one light-detecting element

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS20250208583A1Device for determining the position of a hand of a watch

Publication Date: 2025.06.26 ETA SA MFG HORLOGERE SUISSE

AI summary

A dial (2a, 2b) of a watch (1) including a device (3) for determining the position of at least one hand (24a, 24b) of this watch (1), such a dial (2a, 2b) having a visible face (20a) and a hidden face (20b), the dial (2a, 2b) being formed by a stack (9a, 9b) of thin layers (10, 11, 12, 13, 14) of material extending between these two faces (20a, 20b), each of the layers (10, 11, 12, 13, 14) comprising one or more of the functional elements included in the determination device (3): at least one light-detecting element (23), at least a first light source (4a) and at least a second light source (4b), a stand-alone power supply unit (21) comprising a photovoltaic module (5), and a control unit (7) for managing the operation of each light source (4a, 4b) and of the at least one light-detecting element (23).