Watch Hand Position Detection Using Controlled External Light Paths
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Solution Overview
Problem
Conventional timepieces using external light for hand position detection struggle with inaccurate results due to uncontrolled light incidence from oblique angles, lacking means to prevent such incidence, and fail to adjust detection thresholds based on illuminance environment.
Innovation Solution
The timepiece incorporates a first light detector and a second light detector with distinct mechanisms to limit external light detection, utilizing through holes in the board and gears to control light incidence, and a reference illuminance detector to set detection thresholds based on illuminance levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external light is used for hand position detection without light limiting mechanisms, then the detection system is simple, but the detection accuracy deteriorates due to uncontrolled light incidence from oblique angles
Solution Approach 1:
The patent introduces light limiting mechanisms (light shielding members, light guiding members, and specific through-hole structures) as intermediaries between the external light source and the light receiving element. These intermediaries selectively control light incidence, blocking oblique light while transmitting perpendicular light, thereby improving detection accuracy without requiring complex active control systems
Solution Approach 2:
The patent applies local quality by creating specific light transmission zones through strategically positioned through-holes in the board and gear components. Only light incident through these specific localized paths reaches the light receiving element, ensuring that only perpendicular light is detected while maintaining a relatively simple overall structure
2Reliability
If conventional light detection without illuminance adaptation is used, then the device structure is simple, but the reliability deteriorates under varying illuminance conditions
Solution Approach 1:
The patent implements self-service by enabling the timepiece to automatically detect ambient illuminance levels and adapt its hand position detection thresholds accordingly. The system uses the same light receiving element to perform both illuminance detection and hand position detection, eliminating the need for separate dedicated illuminance sensors while maintaining reliable detection across varying lighting conditions
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 configuration ensures highly reliable hand position detection by controlling light incidence and setting appropriate detection thresholds, minimizing the need for re-adjustment, and maintaining accuracy across varying illuminance conditions.
Implementation Method 1
a light receiving element or other detection means to detect only light incident perpendicular to the display surface
Data Source
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AI summary
Disclosed is an electronic timepiece (100) including: a first light detector (5) and a second light detector (6) that detect external light; a first mechanism (37) that limits an amount of the external light detected by the first light detector; and a second mechanism (21) that limits an amount of the external light detected by the second light detector and has a different structure from a structure of the first mechanism.