Solar Battery Voltage Limiting for IC Downsizing
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Solution Overview
Problem
The high production cost of electronic timepieces due to the large size and cost of control ICs required for over-charge prevention in rechargeable batteries, which also limits flexibility in circuit board arrangement, is a significant issue in analog format electronic timepieces.
Innovation Solution
An electronic timepiece design that uses a solar battery with a lower electromotive force than the deterioration-start voltage of the rechargeable battery, allowing for a downsized control IC without the need for over-charge prevention features, and includes a display device that operates within specific voltage ranges to prevent over-charging, thereby reducing production costs and improving flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If over-charge prevention feature is incorporated into the control IC, then the rechargeable battery is protected from over-charging, but the production cost of the control IC increases
Solution Approach 1:
The patent extracts the over-charging protection function from the control IC by using a solar battery with inherently limited electromotive force. The solar battery's voltage output is naturally capped below the deterioration-start voltage of the rechargeable battery, eliminating the need for active over-charging protection circuitry in the control IC.
Solution Approach 2:
The patent changes the electromotive force parameter of the solar battery to be lower than the deterioration-start voltage of the rechargeable battery. This parameter modification ensures that the solar battery cannot over-charge the rechargeable battery under any conditions, thereby removing the need for complex over-charging protection features in the control IC.
2Reliability
If over-charge prevention feature is incorporated into the control IC, then the rechargeable battery is protected from over-charging, but the dimension of the control IC increases
Solution Approach 1:
The patent removes the over-charging protection functionality from the control IC by designing the solar battery to inherently prevent over-charging through its limited electromotive force. This extraction of the protection function eliminates the need for additional circuitry and reduces the control IC area.
Solution Approach 2:
The patent uses a solar battery with inherently limited voltage output capability as a passive protection mechanism. The solar battery's design ensures it can never over-charge the rechargeable battery, eliminating the need for active protection circuits and reducing control IC size.
3Reliability
If the control IC becomes larger, then the over-charge prevention feature can be implemented, but the flexibility in arranging the circuit board decreases
Solution Approach 1:
The patent extracts the over-charging protection function from the control IC, allowing the circuit board to be designed with greater flexibility. The solar battery's inherent voltage limitation provides protection without requiring additional components that would constrain circuit board layout options.
4Productivity
If the electromotive force of the solar battery is increased to charge the rechargeable battery faster, then the charging speed improves, but the risk of over-charging and battery deterioration increases
Solution Approach 1:
The patent optimizes the electromotive force parameter of the solar battery to be sufficiently high to charge the rechargeable battery effectively, while simultaneously limiting it to below the deterioration-start voltage. This parameter optimization achieves fast charging without over-charging damage.
Solution Approach 2:
The patent converts the potential harm of high-voltage solar batteries into a benefit by designing the solar battery with an electromotive force that is naturally capped below the rechargeable battery's deterioration voltage. This ensures safe charging while maintaining adequate charging speed.
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 design reduces production costs by downsizing the control IC and circuit board, ensures stable operation of the electronic timepiece, and allows for efficient recharging of the rechargeable battery, even under high illumination conditions.
Implementation Method 1
a solar battery that generates electricity by incident light
Data Source
AI summary
The solar battery includes a plurality of cells having a same electromotive force with each other. The display device further includes a display means to display time, and a control means to control operation of the display means. The electromotive force of the solar battery is lower than a deterioration-start voltage of the rechargeable battery. The electromotive force of the cells is higher than a lower-limit driving voltage of the display device, in which a number of such cells equals a total number of cells include in the solar battery minus one. A driving voltage of the display means is lower than the aforementioned lower-limit driving voltage, and an operational voltage of the control means is lower than the aforementioned lower-limit driving voltage.