Retractable Filter Attenuation for Vehicle Head-Up Display Brightness
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Solution Overview
Problem
Existing head-up display systems in vehicles face challenges in adequately adjusting the brightness of projected images between daytime and nighttime driving conditions, with current methods using light emitting diodes or laser sources failing to sufficiently reduce optical power.
Innovation Solution
A device comprising multiple laser sources and attenuation means, such as retractable filters, allows for independent control of optical power through current supply regulation and pulse width modulation, enabling significant adjustment of brightness to match ambient conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser sources are used to increase daytime brightness, then optical power is sufficient during daytime, but brightness cannot be sufficiently reduced at nighttime
Solution Approach 1:
The patent introduces retractable filters as intermediary elements between the laser sources and the projection path. These filters act as mediators that can be inserted or removed from the optical path to attenuate the laser beam intensity. When retracted, they allow full brightness for daytime; when inserted, they reduce intensity for nighttime conditions, enabling the system to overcome the limitation of direct current control and achieve the required 2000:1 brightness adaptation range.
Solution Approach 2:
The patent implements dynamic adaptability by making the filters retractable rather than fixed. The filters can be dynamically positioned in or out of the optical path based on ambient lighting conditions. This dynamic mechanism, combined with PWM control of the laser diodes, enables the system to adapt its brightness output across a wide range (factor of 2000) to match varying environmental conditions from bright daytime to dark nighttime.
2Device complexity
If current supply control is used to adjust brightness, then device complexity is low, but attenuation factor is insufficient (maximum factor of 10-20)
Solution Approach 1:
The patent merges two control mechanisms: PWM control of the laser diode current supply and mechanical retraction/insertion of filters. The PWM provides fine-grained electronic control with a attenuation factor of 10-20, while the retractable filters provide additional mechanical attenuation. By combining these two mechanisms in series, the system achieves a total attenuation factor of up to 2000, overcoming the limitation of using either method alone while maintaining relatively simple device architecture.
3Illumination intensity
If multiple laser sources are combined to increase brightness, then daytime illumination is sufficient, but control precision for nighttime reduction becomes more difficult
Solution Approach 1:
The patent segments the brightness control function into two independent parts: electronic PWM control for fine adjustment and mechanical filter retraction for coarse attenuation. Each laser source can be independently controlled via PWM, and the retractable filters provide an additional layer of attenuation that affects all sources uniformly. This segmentation allows precise control of multiple laser sources while achieving the required nighttime brightness reduction, as each component handles a specific aspect of the control task.
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
The solution provides simultaneous high daytime brightness and low nighttime brightness, achieving an attenuation factor of up to 2000, effectively addressing the limitations of existing technologies.
Implementation Method 1
attenuation means, situated downstream of said source or sources, making it possible to vary the optical power of the light beam, said attenuation means comprising one or more retractable filters, able to be interposed in said beam or beams
Data Source
AI summary
A device for emitting a light beam intended to form an image includes a plurality of sources, each emitting a beam of the laser type. The device is configured to form the light beam by combining the laser beams, and includes attenuation means, situated downstream of the plurality of sources, making it possible to vary the optical power of the light beam. The attenuation means includes one or more retractable filters, and is able to be interposed in the laser beams.