Watch Hand Position Detection Using Extracted Light Blocking
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Solution Overview
Problem
Existing hand position detecting devices for timepieces face challenges in accurately and securely detecting the rotational positions of seconds, center, and hour hands, particularly due to complex assembly requirements and limited light detection efficiency at high speeds.
Innovation Solution
A hand position detecting device with a first driving system that uses a seconds wheel with a circular aperture and arcuate apertures spaced by different light blocking areas, allowing accurate detection by counting successive non-detection events and ensuring secure light passage through apertures in the seconds, center, and hour wheels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a seconds wheel with multiple light-passing apertures is used to detect rotational position, then detection accuracy is improved, but assembly complexity increases due to required precise positioning of multiple wheels
Solution Approach 1:
The invention extracts the light blocking function from the seconds wheel assembly by introducing a separate light blocking area on the main plate. This allows the seconds wheel to have only one light-passing aperture for detection, while the light blocking area provides the necessary blocking function, thereby simplifying the assembly process and reducing positioning requirements.
Solution Approach 2:
The invention segments the light blocking function from the seconds wheel by creating a separate light blocking area on the main plate. This segmentation allows the detection system to use fewer apertures in the seconds wheel while maintaining detection accuracy, thus reducing assembly complexity.
2Productivity
If the seconds wheel rotates at high speeds to improve detection speed, then productivity is improved, but detection reliability decreases because not all apertures can be detected securely
Solution Approach 1:
The invention extracts the light blocking function from the rotating seconds wheel and places it on the stationary main plate. This allows the detection system to rely on a single aperture passing event combined with a stationary blocking area, ensuring reliable detection even at high rotation speeds where multiple aperture detections would be uncertain.
3Illumination intensity
If a seconds wheel with arcuate openings is used to increase light passage, then light intensity is improved, but position detection accuracy decreases because light detection occurs over a range of positions
Solution Approach 1:
The invention applies local quality by creating a concentrated light blocking area at a specific location on the main plate rather than using extended arcuate openings. This localized blocking approach ensures that light detection occurs at a precise rotational position, maintaining detection accuracy while providing sufficient light intensity through the single aperture.
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
Enables accurate and secure detection of the rotational positions of seconds, center, and hour hands, reducing assembly complexity and maintaining detection efficiency even at high speeds.
Implementation Method 1
a light emission element and a photodetection element included in the detector
Implementation Method 2
a light emission element and a photodetection element included in the detector, optically detects... such that the respective rotational positions are determined based on detected signals
Data Source
AI summary
A detection unit detects light passing through apertures provided in a seconds wheel, a center wheel and an hour wheel, respectively, which rotate on the same axis. The apertures in the seconds wheel include a circular aperture provided at a reference position therein, and two apertures provided separated by corresponding arcuate apertures of different lengths from the aperture on its opposite sides, respectively. By counting the number of light non-detection events the detection unit encounters due to the light blocking area covering the detection unit, the rotational position of the seconds wheel is detected accurately and securely.