Electronic Timepiece Hand Position Detection via Dynamic Light Threshold
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Solution Overview
Problem
Conventional electronic timepieces face detection failures due to insufficient illuminance caused by shadows from hands, especially when exposed to varying light environments, leading to inaccurate hand position detection.
Innovation Solution
An electronic timepiece with detection units arranged corresponding to each hand, a control unit that adjusts the threshold for light detection based on environmental illuminance, and a method for re-attempting detection if initial detection fails, ensuring reliable hand position detection without the need for additional light-emitting elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light-receiving elements are installed at positions corresponding to through holes in gears to detect external light for hand position detection, then hand position detection function is enabled, but detection failures occur when shadows from hands block the light path causing insufficient illuminance at the light-receiving elements
Solution Approach 1:
The patent dynamically adjusts the threshold value for light detection based on the detected illuminance level. When illuminance is high, a higher threshold is used; when illuminance is low, a lower threshold is used. This dynamic adaptation allows reliable hand position detection across varying light conditions without requiring additional light-emitting elements.
Solution Approach 2:
The invention changes the detection parameter (threshold value) according to the environmental illuminance conditions. By adjusting this parameter dynamically, the system maintains detection reliability whether the watch is in bright sunlight or dim indoor lighting, resolving the contradiction between varying illumination intensity and consistent detection reliability.
2Reliability
If additional light-emitting elements are added to ensure sufficient illuminance for detection, then detection reliability improves, but device complexity and size increase
Solution Approach 1:
The patent uses the existing ambient light environment to perform detection, making the system self-sufficient without requiring additional active light sources. The light-receiving elements detect external light that naturally passes through the through holes, and the system adapts to the available light conditions through dynamic threshold adjustment, eliminating the need for extra light-emitting components.
Solution Approach 2:
The existing through holes in the gears serve dual purposes: they allow light transmission for position detection and simultaneously act as the detection aperture itself. This multi-functionality eliminates the need for separate light-emitting and light-receiving structures, reducing device complexity while maintaining detection reliability.
3Measurement precision
If the threshold for light detection is set high to avoid false detection, then detection accuracy improves, but detection fails in low illuminance environments
Solution Approach 1:
The threshold value is dynamically adjusted based on the detected illuminance level. In bright environments, a high threshold maintains detection accuracy by filtering out ambient light variations. In dim environments, the threshold is automatically lowered to enable detection while still distinguishing valid hand positions from noise, thus maintaining accuracy across all illuminance conditions.
Solution Approach 2:
The detection threshold parameter is changed adaptively according to ambient illuminance conditions. This parameter adjustment allows the system to maintain optimal detection accuracy whether the threshold needs to be high (in bright light) or low (in dim light), resolving the contradiction between fixed threshold accuracy and variable illuminance 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
The solution ensures accurate hand position detection across a wide range of illuminance levels, preventing detection failures and allowing for miniaturization of the timepiece design by eliminating the need for extra light-detection components.
Implementation Method 1
through holes that transmit light are provided in a plurality of gears that constitute a wheel train mechanism
Implementation Method 2
a light receiving element for detecting external light is installed at positions corresponding to through holes
Data Source
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AI summary
An electronic timepiece includes a plurality of hands; a plurality of detection units that detect external light, arranged corresponding to the plurality of hands; and a control unit, wherein the control unit is configured to perform external light detection operations that respectively determine whether or not external light of a threshold value or more is detected at the plurality of detection units while moving the plurality of hands by a predetermined distance, respectively, and when there is a hand among the plurality of hands for which the external light detection operation detected external light and when there is another hand among the plurality of hands for which the external light detection operation did not detect external light, perform the external light detection operation for said another hand again.