Solar Timepiece Illuminance Detection Circuit
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Solution Overview
Problem
Existing timepieces with solar cells face challenges in accurately detecting power generation states due to the overcharge protection circuit short-circuiting the solar cell, leading to erroneous illuminance detection and potential incorrect power saving mode activation, even when illuminance is sufficient.
Innovation Solution
A timepiece configuration that includes a solar cell, a secondary battery, an overcharge prevention circuit, and an illuminance detection circuit connected in parallel, where the control unit short-circuits the solar cell to determine if illuminance is above a predetermined level when the overcharge prevention circuit is activated, allowing accurate detection of power generation states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the overcharge protection circuit is activated to prevent overcharge of the secondary battery, then battery safety is improved, but the solar cell is short-circuited causing erroneous illuminance detection
Solution Approach 1:
The patent introduces a switching circuit as an intermediary component that can selectively connect either the illuminance detection circuit or the overcharge protection circuit to the solar cell based on operational state. When the overcharge protection circuit is activated, the switching circuit disconnects the illuminance detection circuit from the solar cell, preventing the short-circuit effect from affecting measurement accuracy. This intermediary mechanism allows both circuits to coexist without interfering with each other's functionality.
2Reliability
If the solar cell is short-circuited by the overcharge protection circuit, then overcharge prevention is achieved, but the detection value of the illuminance detection circuit becomes lower than actual value
Solution Approach 1:
The patent implements a dynamic switching mechanism that adapts the circuit configuration based on the operational state of the battery. The control circuit monitors battery charge status and dynamically switches between two operational modes: (1) During normal operation, the illuminance detection circuit is connected to measure solar cell output; (2) When overcharge protection is activated, the switching circuit reconfigures to disconnect the illuminance detection from the solar cell. This dynamic adaptation prevents information loss by ensuring measurements are only taken when the circuit configuration supports accurate readings.
3Use of energy by moving object
If the timepiece switches to power saving mode based on erroneous illuminance detection, then energy consumption is reduced, but proper operation is lost when illuminance is sufficient
Solution Approach 1:
The patent implements a feedback mechanism where the control circuit continuously monitors both the battery charge status and the operational state of the overcharge protection circuit. When the overcharge protection circuit is activated, the control circuit receives feedback about this state and uses it to determine that the solar cell is generating sufficient power (since overcharge protection only activates when power generation exceeds battery acceptance). Based on this feedback, the control circuit correctly maintains full operational mode instead of erroneously switching to power saving mode, thus ensuring reliable operation while still managing power consumption appropriately.
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 detection of solar cell power generation even when the secondary battery is close to full charge, preventing erroneous power saving mode activation and ensuring proper operation when illuminance is sufficient.
Implementation Method 1
a solar cell (G) that has a solar panel, a secondary battery (E) that is charged from the solar cell
Data Source
AI summary
Provided is a timepiece including a solar cell that has a solar panel, a secondary battery that is charged from the solar cell, an overcharge prevention circuit that detects a charged state of the secondary battery, and a control unit that short-circuits the solar cell and determines that illuminance of light illuminating the solar panel is equal to or higher than predetermined illuminance in a case where the overcharge prevention circuit is detected to be in an overcharge state.