Transparent Enamel Watch Backlighting With Mirror-Directed Light

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Solution Overview

Problem

Watches with plique-à-jour enamel decoration are not effectively backlit when worn on the wrist, as ambient light does not enter through the case back, diminishing the visibility and brilliance of the enamels.

Innovation Solution

Incorporating a light source and a mirror arrangement within the watch to backlight the decorative structure, where the mirror reflects light emitted by the source onto the rear surface of transparent and/or translucent parts of the enamel, allowing light to pass through and exit via the front glass.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the watch is worn on the wrist, then the watch is convenient to use, but ambient light cannot enter through the lower glass to backlight the decorative structure

Engineering Contradiction:
Improveconvenience of wearingVSAvoidbacklighting of decorative structure
Core Design Contradiction:
Ease of operationVSIllumination intensity

Solution Approach 1:

A light guide is introduced as an intermediary element between the light source and the decorative structure. The light guide transmits light from the source positioned in the case back through the lower glass to the rear surface of the decorative structure, enabling backlighting without requiring ambient light to enter through the case back.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The natural light path relying on ambient light entering through the case back is replaced with an artificial lighting system consisting of a light source, light guide, and mirror arrangement. This substitution allows the decorative structure to be backlit independently of external ambient light conditions.

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

2Illumination intensity

If a light source is added to backlight the decorative structure, then the brilliance of the enamels is enhanced, but the device complexity increases

Engineering Contradiction:
Improvebrilliance of enamelsVSAvoidstructure of light source and mirror arrangement
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The light guide serves as a mediator that simplifies the light transmission path. Instead of directly positioning the light source close to the decorative structure, the light guide conducts the light from a conveniently positioned source in the case back, reducing structural complexity while maintaining effective backlighting.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The light guide performs multiple functions: it transmits light from the source, directs it toward the decorative structure, and can be integrated with the existing case back structure. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity.

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

3Illumination intensity

If the light source is positioned to emit light through the lower glass, then the decorative structure can be backlit, but the light may not reach the transparent parts effectively

Engineering Contradiction:
Improvebacklighting through lower glassVSAvoidalignment of light path with transparent parts
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The light guide acts as a precision intermediary that accurately directs light from the source to the transparent parts of the decorative structure. It compensates for alignment uncertainties by conducting light along a controlled path through the case back and onto the rear surface of the enamel structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The direct mechanical alignment of light source with transparent parts is replaced with an optical path defined by the light guide and mirror system. This optical substitution allows for more flexible and precise light delivery to the transparent areas without requiring complex mechanical positioning.

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

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

Ensures that the decorative structure is backlit both in dimly lit spaces and at night, enhancing the visibility and brilliance of the enamels, regardless of ambient light conditions.

Implementation Method 1

the mirror being arranged below the light source and below a rear surface of the decorative structure. The light source and the mirror are arranged in such a way that this mirror can receive most of the light energy emitted by the light source, when the latter is active, and can reflect the light from this light source in such a way that this reflected light is finally at least partially incident on the back surface of the decorative structure

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP4421568B1Watch provided with a transparent or/and translucent decorative structure, in particular a push-to-pass enamel
Publication Date: 2025.11.05 THE SWATCH GRP RES & DEVELONMENT LTD
  • EP4421568B1 patent drawingFigure 1
  • EP4421568B1 patent drawingFigure 2~3
  • EP4421568B1 patent drawingFigure 4~5

AI summary

The watch (2) includes a case (4), a movement (6) incorporated in the case, a lower glass (10) forming at least part of the back (12), a decorative structure (16) visible axially from the side of the front face (20) of the watch and comprising at least one transparent and/or translucent part (16a) which is visible axially through the lower glass.The watch further includes a light source (26) and a mirror (28), the light source being arranged to emit substantially in the direction of the mirror which is arranged below the light source and below a rear surface (18) of the decorative structure, the mirror receiving most of the light energy emitted by the light source, and reflecting the light from this light source in such a way that the reflected light is ultimately at least mostly incident on the rear surface of the decorative structure in at least one area (18a) defined by said at least a transparent and/or translucent part.