Electronic Timepiece Hand Position Detection Using Transient Current
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Solution Overview
Problem
Existing hand position detection methods in analog timepieces consume excessive power and may inaccurately determine the position of hands due to small current variations in light detection.
Innovation Solution
The method involves applying a voltage to a detector after light passes through wheel holes, utilizing parasitic capacity to amplify current output by transient response, and comparing the current value with a threshold before reaching a steady state to enhance accuracy and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light-emitting element is illuminated after voltage is applied to the light-receiving element and detection is performed in the stable period, then the current output is stable, but the power consumption is excessive and detection accuracy is reduced due to small current variations
Solution Approach 1:
The light-emitting element is illuminated in advance before voltage is applied to the light-receiving element. This preliminary action stores light energy in the parasitic capacity of the detector, enabling a strong transient response current when voltage is subsequently applied, thereby improving detection accuracy while allowing for reduced power consumption operation
2Measurement precision
If detection is performed in the stable period, then the current output is stable, but the current variations are small making accurate detection difficult
Solution Approach 1:
The light-emitting element is illuminated in advance to charge the parasitic capacity of the detector. When voltage is then applied to the detector, a large transient response current flows as the stored energy is discharged, providing strong current variations that improve detection sensitivity and accuracy
Solution Approach 2:
The detection timing is changed from the stable period to a transient period. By detecting the current during the transient response phase rather than the stable period, the system captures large current variations that provide better detection signals with higher accuracy
3Measurement precision
If the light-emitting element is illuminated continuously to ensure sufficient light for detection, then detection accuracy is maintained, but power consumption increases
Solution Approach 1:
The light-emitting element is illuminated in advance for a predetermined period before detection. This preliminary illumination stores sufficient light energy in the detector's parasitic capacity, allowing the system to use a brief detection pulse rather than continuous illumination, thereby reducing overall power consumption while maintaining detection accuracy
Solution Approach 2:
Instead of continuous illumination, the system uses periodic action with distinct illumination and detection phases. The light-emitting element illuminates for a predetermined period, then stops, and detection is performed during a brief transient period, creating an efficient periodic operation cycle that reduces power consumption
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 approach allows for high-accuracy hand position detection with reduced power consumption by amplifying current values through transient response, avoiding false negatives and minimizing power usage.
Implementation Method 1
a detector corresponding to the wheel, the detector being configured to detect light that passes through the hole of the wheel in response to voltage being applied to the detector and configured to output current corresponding to an intensity of the detected light
Data Source
AI summary
An electronic timepiece includes: a hand; a wheel corresponding to the hand and having a hole; a detector corresponding to the wheel, the detector being configured to detect light that passes through the hole of the wheel in response to voltage being applied to the detector and configured to output current corresponding to an intensity of the detected light; and a processor. The processor obtains, at a predetermined timing, a current-based value that is based on the current output by the detector. The processor determines whether or not the current-based value is greater than or equal to a predetermined threshold. Based on the determination, the processor performs position detection of the hand. The predetermined timing is earlier than a timing at which the current-based value, which is based on the current output by the detector, becomes a value in a steady state.