Laser Beam Attenuation via Electrochromic Mirrors for Head-Up Displays
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Solution Overview
Problem
Current head-up display systems in vehicles face challenges in adapting the brightness of projected images to varying ambient light conditions, particularly struggling to reduce optical power sufficiently between daytime and nighttime driving, and existing technologies using light-emitting diodes or laser sources have limitations in achieving the necessary luminosity adjustments without moving parts.
Innovation Solution
A device comprising multiple laser sources that combine to form a single light beam, with attenuation means such as electro-chrome mirrors and current control mechanisms to vary the optical power, allowing for significant adjustments in brightness without moving parts, using pulse-width modulation and linear current regulation to achieve desired attenuation factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If LED light sources are used with current control, then brightness adjustment is achievable, but daytime brightness remains insufficient
Solution Approach 1:
The patent changes the fundamental parameter of light source selection from LEDs to laser diodes, which inherently provide higher luminous intensity. This parameter change enables sufficient daytime brightness while maintaining ease of operation through electronic current control and electrochromic attenuation mechanisms.
2Ease of operation
If current control technologies are used to adjust brightness, then some attenuation is achieved, but the minimum pulse duration and current intensity requirements limit the attenuation range
Solution Approach 1:
The patent replaces the mechanical/current-control-based brightness adjustment system with an electro-optic system using electrochromic mirrors. This substitution eliminates the minimum pulse duration and current intensity constraints inherent in LED/diode current control, enabling continuous attenuation from 100% to 0.05% of maximum brightness.
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 high daytime luminosity and low nighttime luminosity with precise control over optical power, achieving attenuation factors of at least 1000 or 2000, ensuring optimal visibility in different driving conditions without mechanical components.
Implementation Method 1
the attenuation means comprise one or more electrochromic mirrors. They may, for example, be arranged in series along the path of said beam(s). Their attenuation factor can thus be combined.
Data Source
Figure 1~3
Figure 4
AI summary
The invention concerns a device for emitting a light beam (10) intended to form an image, the device comprising one or more sources (4, 5, 6), each emitting a laser-type beam (7, 8, 9), the device being designed to form the light beam (10) from the one laser beam (7, 8, 9) or from a combination of the laser beams, the device comprising attenuation means (12), disposed downstream of the source(s) (3, 4, 5), enabling the optical power of the light beam (10) to be varied by transmitting and/or reflecting the beam(s) as a function of a current feeding the attenuation means (12).