HUD Backlighting Light Recycling via Beam Splitter
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Solution Overview
Problem
Conventional heads-up displays for vehicles, utilizing TFT-LCD screens, suffer from low luminous power transmission due to polarizers, leading to high energy consumption and heat dissipation issues, requiring bulky components and significant back-lighting.
Innovation Solution
A projection system with a back-lighting device that includes a light source, collimating lenses, and reflective means to recycle light, utilizing a high reflection coefficient metallic coating on lenses and support structures to enhance light transmission and reduce energy consumption, while minimizing optical interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a TFT-LCD screen with polarizer is used for heads-up display, then the display can show information to the driver, but the luminous power transmission is reduced to around 5% due to the polarizer blocking most light from LED back-lighting
Solution Approach 1:
The patent recovers light that would otherwise be discarded by the polarizer. A beam splitter is positioned at 45 degrees to the optical axis to redirect reflected light from the liquid crystal layer back through the liquid crystal layer toward the screen, allowing the system to utilize light that would normally be blocked and lost, thereby improving luminous power transmission efficiency
Solution Approach 2:
The beam splitter acts as an intermediary optical element that redirects light paths. It intercepts light reflected from the liquid crystal layer and redirects it back through the liquid crystal layer, enabling the system to recover and reuse light that would otherwise be blocked by the polarizer, thus improving overall light transmission efficiency
2Illumination intensity
If high power LED back-lighting is used to compensate for low transmission, then sufficient luminous power reaches the screen, but significant energy is consumed and heat is generated requiring bulky heat dissipators
Solution Approach 1:
The patent recovers light that would otherwise be discarded by the polarizer. A beam splitter is positioned at 45 degrees to the optical axis to redirect reflected light from the liquid crystal layer back through the liquid crystal layer toward the screen, allowing the system to utilize light that would normally be blocked and lost, thereby improving luminous power transmission efficiency
Solution Approach 2:
The beam splitter acts as an intermediary optical element that redirects light paths. It intercepts light reflected from the liquid crystal layer and redirects it back through the liquid crystal layer, enabling the system to recover and reuse light that would otherwise be blocked by the polarizer, thus improving overall light transmission efficiency
3Illumination intensity
If high power back-lighting is used to achieve sufficient image luminosity, then the display is visible in all conditions, but the back-lighting device and heat dissipators become bulky
Solution Approach 1:
The patent recovers light that would otherwise be discarded by the polarizer. A beam splitter is positioned at 45 degrees to the optical axis to redirect reflected light from the liquid crystal layer back through the liquid crystal layer toward the screen, allowing the system to utilize light that would normally be blocked and lost, thereby improving luminous power transmission efficiency
Solution Approach 2:
The beam splitter acts as an intermediary optical element that redirects light paths. It intercepts light reflected from the liquid crystal layer and redirects it back through the liquid crystal layer, enabling the system to recover and reuse light that would otherwise be blocked by the polarizer, thus improving overall light transmission efficiency
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 system achieves improved luminous power efficiency, reduced energy consumption, and smaller size by recycling and modifying light characteristics, thereby enhancing the display's luminosity and reducing heat dissipation needs.
Implementation Method 1
reflective means disposed on the face of the lens situated on the side with the light source, designed to let the light pass through in the direction of the screen and reflect toward the screen nearly all of the light propagating in the direction of the lens
Implementation Method 2
at least one lens adapted to collimate the light coming from the light source in the direction of the liquid crystal screen
Data Source
AI summary
The invention relates to a projection system for a display, in particular a heads-up display, comprising a liquid crystal screen (12) and a back-lighting device (14) for said screen (12). The projection system is characterized in that said back-lighting device (14) comprises at least one light source (16) emitting light towards the screen (12), at least one lens (38a, 38b) suitable for collimating the light from the light source (16) towards the liquid-crystal screen (12), and reflective means (26) arranged on the surface of the lens (38a, 38b) located on the side of the light source (16), arranged such as to allow light to pass through same towards the screen (12) and to reflect towards the screen (12) almost all of the light propagating towards the lens (38a, 38b).