Transparent Display Optics Using Dichroic Filtering Against Stray Light
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Solution Overview
Problem
Display systems in motor vehicles are sensitive to external light, causing interference, reflections, stray light, and potential damage to the light source due to solar radiation.
Innovation Solution
A display device comprising a light source, a diffractive optical element, and a dichroic filter that filters external radiation and allows only a specific wavelength range to enter, while using a splitter and multiple diffractive optical elements to create different colored symbols from a single light source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a transparent or partially transparent surface is used for display, then aesthetic appearance is improved with floating symbols, but sensitivity to external light increases causing interference and heating
Solution Approach 1:
A dichroic filter is introduced as an intermediary component between the external environment and the display system. This filter selectively transmits the wavelength range needed for display operation while blocking harmful external radiation, thus protecting the light source and maintaining display quality without compromising the aesthetic transparent design
Solution Approach 2:
The dichroic filter provides selective wavelength transmission properties, allowing only specific wavelength ranges to pass through while blocking others. This local quality approach enables the system to maintain transparency for visible light while blocking harmful infrared or ultraviolet radiation that causes heating and interference
2Adaptability or versatility
If multiple light sources are used to create different colored symbols, then color versatility is improved, but device complexity and space requirements increase
Solution Approach 1:
A single light source is designed to emit across a broad wavelength range, making it universal enough to produce multiple colors. By combining this multi-wavelength capability with a diffractive optical element that can be positioned to select different wavelength ranges, the system achieves color versatility without needing multiple separate light sources
Solution Approach 2:
The system uses a movable diffractive optical element that can be dynamically positioned to select different wavelength ranges from the single light source. This dynamic adjustment allows the same physical component to produce different colors by changing its position, thereby achieving versatility without increasing device complexity
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
Reduces interference and stray light, protects the light source from overheating, and allows for aesthetic display of symbols without external light disruption, while using a single light source for multiple colors.
Implementation Method 1
a dichroic filter placed in the path of said image light beam and the passband of which at least partially covers said wavelength range so as to at least partially transmit said image light beam
Implementation Method 2
a diffractive optical element, the operating range of which is adapted to said wavelength range and which is arranged to receive said source light beam and to transmit an image light beam
Data Source
AI summary
The invention relates to a display device (1) comprising:—a light source (20) designed to generate a source light beam (S) extending over a predetermined wavelength range; —a diffractive optical element (40), the operating range of which is adapted to said wavelength range and which is arranged to receive said source light beam (S) and to transmit an image light beam (I); and —a dichroic filter (50) placed in the path of said image light beam and the passband of which at least partially covers said wavelength range so as to at least partially transmit said image light beam.