Electro-Optic Rearview Mirror Drive Circuit Segmentation
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Solution Overview
Problem
Existing electro-optic rearview mirror systems face challenges in providing improved drive circuitry for multiple electro-optic rearview mirror elements, particularly in ensuring that if one mirror is shorted, it does not affect the functionality of the other mirrors, and in efficiently managing glare protection and reflectance levels.
Innovation Solution
A drive circuit configuration that differentially senses the voltage of the inside electro-optic rearview mirror element, ensuring that if the outside element is shorted, the voltage of the inside element remains unchanged, and includes a controller responsive to ambient and glare light sensors to generate voltage control signals, with a selection circuit to selectively supply drive voltage to the mirror elements, using power transistors and capacitors to manage voltage and current efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate drive circuits and power conditioning means are provided for each mirror, then reliability is improved (disabling one mirror does not affect others), but device complexity increases
Solution Approach 1:
The drive circuit is segmented into separate functional blocks: a first power conditioning means for the inside electro-optic mirror element and a second power conditioning means for the outside electro-optic mirror elements. This segmentation allows independent control and protection of each mirror element, ensuring that a failure in one does not affect the others, while maintaining manageable circuit complexity through modular design.
2Device complexity
If a single drive circuit controls multiple mirror elements, then device complexity is reduced, but reliability deteriorates (one shorted mirror affects all mirrors)
Solution Approach 1:
The power conditioning means is divided into distinct segments - a first power conditioning means connected to the inside mirror element and a second power conditioning means connected to the outside mirror elements. This segmentation creates electrical isolation between mirror elements, allowing the system to maintain lower complexity than fully separate circuits while preventing a shorted mirror from affecting others through the segmented architecture.
3Measurement precision
If differential sensing is implemented for voltage detection, then measurement precision is improved (accurate voltage sensing despite shorts), but device complexity increases
Solution Approach 1:
A differential sensing mechanism is implemented within the power conditioning means to detect voltage across the inside electro-optic mirror element. This differential sensing acts as an intermediary measurement approach that accurately determines the voltage state of the mirror element even when other parts of the system experience shorts, providing precise control information without requiring complex external monitoring equipment.
Data Source
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AI summary
An electro-optic rearview mirror system is provided. The electro-optic rearview mirror system includes an inside electro-optic rearview mirror element and an outside electro-optic rearview mirror element in series with the inside electro-optic rearview mirror element. A drive circuit is in electrical communication with the inside electro-optic rearview mirror element and the outside electro-optic rearview mirror element and includes a first power operational amplifier and a second power operational amplifier, both of which are configured as voltage followers. The drive circuit is configured to apply overvoltage to the inside electro-optic rearview mirror element if the outside electro-optic rearview mirror element is shorted.