Free Space Optical Humidity Measurement in Watch Cases
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Solution Overview
Problem
Existing watch humidity measurement devices are unsuitable for mechanical watches due to battery requirements, increase product volume, and manufacturing costs, and are bulky and expensive, making it difficult to monitor relative humidity levels without opening the watch case.
Innovation Solution
A free space optical system with an emitter and receiver module, along with a control unit, measures humidity by evaluating the absorption of light beams by water vapor inside the watch case, using reflective elements and optical cavities to determine relative humidity levels without the need for waveguides or batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an electronic measuring device with battery is used to measure relative humidity inside the watch case, then the humidity measurement function is achieved, but the device becomes bulky and requires battery replacement, reducing suitability for mechanical watches
Solution Approach 1:
The patent replaces the electronic measuring device with a mechanical-optical system. A light source emits light through the watch case crystal, and a photodetector on the opposite side measures light absorption. Water vapor inside the case absorbs specific wavelengths of light, and the degree of absorption indicates humidity level. This mechanical-optical system eliminates the need for batteries and electronic components, making the watch suitable for mechanical movements while maintaining measurement capability.
Solution Approach 2:
The patent extracts the humidity measurement function from a bulky electronic module and implements it through the watch case's existing optical path. By using the crystal and back as part of the measurement system, the solution removes the need for dedicated humidity sensor housing and power supply components, significantly reducing volume.
2Measurement precision
If an electronic measuring device is used to monitor humidity inside the watch case, then humidity detection is enabled, but the device becomes expensive and increases manufacturing cost
Solution Approach 1:
The patent makes the watch case components serve multiple functions: the crystal and back serve both their primary protective and display functions and as optical elements for humidity measurement. This multi-functionality eliminates the need for separate humidity sensor assemblies, reducing component count and manufacturing cost while enabling humidity monitoring capability.
3Ease of operation
If the watch case is opened to check humidity levels, then direct observation is possible, but the seals must be replaced and a watchmaker's intervention is required, increasing cost and complexity
Solution Approach 1:
The patent enables the watch to self-monitor its own humidity levels without requiring external intervention. The optical system continuously or periodically measures light absorption through the crystal, and the watchmaker can read the humidity indication directly from the dial or through a magnifying lens, eliminating the need to open the case or replace seals for humidity checking.
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 solution provides a cost-effective, reliable, and fast method to monitor relative humidity levels inside the watch case, allowing for early detection of water-resistance defects without opening the watch, suitable for both mechanical and electronic watches.
Implementation Method 1
an emitter module for emitting at least one light beam; a receiver module for receiving said at least one light beam; said at least one light beam emitted by the emitter module defining an optical path partly comprised in said case and extending as far as the receiver module
Implementation Method 2
the control unit being configured to evaluate the absorption of said light beam by the water vapour capable of being present inside said enclosure of the case
Data Source
AI summary
An assembly (1) for measuring a relative humidity level inside a watch (2), comprising the watch (2) and a device (4) for determining the humidity level present in the enclosure (9) of a case (3) of this watch (2), the determination device (4) comprising a free space optical system and a control unit (7). The system includes: an emitter module (5) for emitting at least one light beam (8); and a receiver module (6) for receiving the at least one light beam (8); the control unit (7) being connected to the modules (5, 6) and the at least one light beam (8) emitted by the emitter module (5) defining an optical path partly comprised in the case (3) and extending as far as the receiver module (6) and the control unit (7) being configured to evaluate the absorption of the light beam (8) by the water vapour capable of being present inside the enclosure (9) of the case (3).