Luminous Watch Hand Light Guide Replication
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for manufacturing luminous watchmaking hands, particularly those using fluorescent needles, face challenges such as difficulty in holding liquid resin in pre-cut metal sheets and delicate handling of sacrificial films, leading to incomplete light extraction and visible clips.
Innovation Solution
A method involving the assembly of needle bodies with a pre-cut light guide using a transparent, non-diffusing glue, where the light guide is manufactured through replication of micro-structures on a plastic substrate with UV-embossing, allowing for efficient light coupling and extraction, and final cutting to ensure complete light emission around the needle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If liquid resin is deposited onto a pre-cut metal sheet to form a light guide, then the light guide structure is created, but it is difficult to keep the liquid resin contained within the opening and requires delicate handling of sacrificial films
Solution Approach 1:
The metal sheet is pre-cut with a recess before resin deposition, creating a containment structure in advance. This preliminary action eliminates the need for sacrificial films during resin application, making the process more reliable and easier to manufacture while ensuring the resin remains contained within the opening.
2Illumination intensity
If the needle tip attachment is cut beyond the resin light guide to allow light extraction, then light extraction is enabled, but the attachment remains visible which affects aesthetics
Solution Approach 1:
The light guide structure is designed with differentiated zones: a first portion with light extraction structures for illumination, and a second portion extending beyond it that is optically isolated and invisible. This local quality differentiation allows light extraction where needed while maintaining aesthetic appearance in visible areas, as the second portion appears transparent or invisible to the observer.
3Ease of manufacture
If a sacrificial film is used to seal the opening around the needle, then liquid resin containment is achieved, but the handling is particularly delicate and complex
Solution Approach 1:
The sacrificial film step is completely removed from the manufacturing process. Instead, a recess is created in the metal sheet that provides inherent containment for the liquid resin. This extraction of the sacrificial film simplifies the process by eliminating delicate handling requirements and reducing overall process complexity while maintaining resin containment effectiveness.
4Illumination intensity
If the attachment is made visible to allow light extraction all around the needle, then complete light extraction is achieved, but the visible clip detracts from the aesthetic appearance
Solution Approach 1:
The light guide is designed with a first portion that is visible and contains light extraction structures for illumination, and a second portion that extends beyond the first portion and is optically isolated to be invisible. This local quality differentiation allows the attachment to remain functional for light extraction while preventing aesthetic harm in visible areas, as the second portion appears transparent or invisible to the observer.
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 method enables the production of luminous watch hands with uniform illumination, avoiding visible clips and improving manufacturing efficiency by ensuring complete light extraction and optical isolation, resulting in a more aesthetically pleasing and functional timepiece display.
Implementation Method 1
The replication of the microstructures is carried out by UV embossing
Implementation Method 2
optical coupling of light in a light guide
Implementation Method 3
a medium refractive index layer whose function is to guide the fluorescent light to the edges of the needle
Implementation Method 4
structured to create areas of light coupling and extraction
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Method for manufacturing a luminous watch hand (80), according to which, on the one hand, in a first group of operations (1000), at least one light guide (30) or a strip of light guides (35) is manufactured separately by replicating microstructures initially made on a master (1), and on the other hand, in a second group of operations (2000), at least one hand body (50) or a strip of hand body (55) is manufactured separately, which is assembled with said at least one light guide (30) or said strip of light guides (35) by a gluing operation (600) and an assembly operation (700), before finishing said luminous hand (80) by a final cutting operation (800).