Multifunction Light Pipe for Rearview Mirror Glare Sensing
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Solution Overview
Problem
Existing interior rearview mirror assemblies face challenges in effectively sensing glare light and providing user-activated functions due to the placement of light sensors and switches, which can be obstructed by the mirror reflective element and lack intuitive user interfaces for controlling electrochromic dimming.
Innovation Solution
A multi-function light pipe is integrated into the mirror assembly, acting as both a conduit for guiding glare light to a rear-facing light sensor and an actuator for a switch, allowing the sensor to be placed on the printed circuit board's rear side while enabling an indicator LED to be visible and usable through the same optics, with a pivot mechanism for user activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light sensor is placed on the front side of the mirror assembly to sense glare light, then the sensing function is improved, but the mirror reflective element obstructs the sensor and reduces measurement precision
Solution Approach 1:
The light sensor is inverted and placed on the rear side of the printed circuit board, facing away from the mirror reflective element. The light pipe extends through the mirror head to allow the sensor to receive glare light from the front while being positioned on the rear side, thus eliminating obstruction by the mirror reflective element while maintaining sensing accuracy.
Solution Approach 2:
A light pipe is introduced as an intermediary component to transmit glare light from the front of the mirror head to the light sensor on the rear side. This mediator allows the sensor to be positioned on the rear side away from the mirror reflective element while still receiving the necessary light for accurate glare sensing.
2Device complexity
If the light sensor and indicator LED share the same light pipe, then device complexity is reduced, but the light sensor may be affected by indicator LED light emission
Solution Approach 1:
The indicator LED is activated only during specific periods (when the user presses the light pipe actuator or when ambient light levels require indication), while the light sensor operates continuously. This periodic activation of the LED prevents it from continuously interfering with the sensor, allowing both components to share the same light pipe without compromising sensor reliability.
3Ease of manufacture
If the switch is placed on the printed circuit board for easy manufacturing, then ease of manufacture is improved, but user accessibility and ease of operation are reduced
Solution Approach 1:
The light pipe serves a dual function: it guides light to the sensor and acts as a mechanical actuator for the switch. When the user presses the exposed end of the light pipe, this mechanical pressure is transmitted through the light pipe to actuate the switch on the printed circuit board, providing easy user access while maintaining the manufacturing advantage of having the switch on the PCB.
Solution Approach 2:
The light pipe is designed to perform multiple functions: it serves as an optical conduit for the light sensor, as an indicator display element, and as a mechanical actuator for the switch. This multi-functionality eliminates the need for separate components, simplifying the overall structure while improving both ease of manufacture and user accessibility.
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 configuration allows for efficient glare sensing and user-friendly control of the electrochromic mirror's dimming function, ensuring the light sensor operates independently of the indicator LED and provides a clear, intuitive interface for driver interaction.
Implementation Method 1
A multi-function light pipe or conduit or guide is disposed at the mirror head with (i) a first end disposed at and spanning or encompassing at least part of each of the light sensor, the indicator LED and the switch
Implementation Method 2
an indicator light emitting diode (LED) and (iii) a switch or button (that is activated via pressing the switch or button or otherwise physically moving a portion of the switch or button relative to the substrate of the printed circuit board)
Implementation Method 3
an interior rearview mirror assembly that comprises a variable dimming electro-optic mirror reflective element
Data Source
AI summary
A vehicular interior rearview mirror assembly includes a mirror head having a mirror casing and an electro-optic mirror reflective element. A printed circuit board is disposed in the mirror head and includes (i) a light sensor, (ii) an indicator LED and (iii) an electronic switch. A multi-function light pipe is disposed at the mirror head with (i) a first end at the light sensor, the indicator LED and the electronic switch, and (ii) a second end at a perimeter region of the mirror head so as to be viewable and accessible by the driver of the vehicle. The light sensor senses light from rearward of the vehicle via the light pipe. Light emitted by the indicator LED, when energized, is viewable by the driver via the light pipe. The light pipe actuates the electronic switch responsive to a user actuation at the second end of the light pipe.