Reflective Polarizers for Head-Up Display Heat Reduction
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Solution Overview
Problem
Image-generating devices in vehicle head-up displays experience excessive heating due to the absorption of light by absorptive polarizers, which affects the brightness and efficiency of the display.
Innovation Solution
Incorporating additional reflective polarizers upstream and downstream of the liquid-crystal display to reflect light components that would otherwise be absorbed, reducing heat generation and maintaining image brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If absorptive polarizers are used in the liquid-crystal display, then light can be selectively transmitted to create the image, but excessive heating occurs in the device
Solution Approach 1:
The invention converts the harmful absorbed light energy into beneficial reflected light that can be reused. The reflective polarizers reflect the absorbed light components back through the liquid crystal display, allowing the light to be utilized again rather than being wasted as heat, thus converting the harmful heating effect into a beneficial lighting effect
Solution Approach 2:
Instead of discarding the light energy that is absorbed by the polarizers (which causes heating), the invention recovers this energy by using reflective polarizers to bounce the light back through the display. This recovered light can be reused to illuminate the display again, improving efficiency and reducing heat generation
2Reliability
If absorptive polarizers are used to selectively transmit light components, then the liquid-crystal display can function properly, but light energy is lost as heat
Solution Approach 1:
The harmful absorbed light energy is converted into beneficial reflected light by using reflective polarizers. The light that would normally be absorbed and lost is instead reflected back through the liquid crystal display, allowing it to be reused for illumination and converting energy loss into energy recovery
Solution Approach 2:
The invention recovers light energy that would otherwise be discarded as heat. By using reflective polarizers, the absorbed light components are reflected back through the display and can be reused, thereby recovering energy that would have been lost and improving overall system 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 solution effectively limits heating in the image-generating device while maintaining a bright image by reflecting unwanted light components, thus enhancing the device's performance and longevity.
Implementation Method 1
a first additional polarizer located on the path of the light, upstream of said liquid-crystal display, and a second additional polarizer located on the path of the light, downstream of said liquid-crystal display, the first additional polarizer being a first reflective polarizer suitable for reflecting a component of the light having a polarization orthogonal to said entrance polarization
Implementation Method 2
the first additional polarizer being a first reflective polarizer suitable for reflecting a component of the light having a polarization orthogonal to said entrance polarization and the second additional polarizer being a second reflective polarizer suitable for reflecting a component of the light having a polarization orthogonal to said exit polarization
Data Source
AI summary
An image generating device (3) comprises a liquid-crystal screen (8) and a light source (5). The liquid-crystal screen (8) comprises a matrix of liquid crystals interposed between an input polariser and an output polariser. The image generating device (3) comprises a first additional polariser (16) located on the light path, upstream of said liquid-crystal screen (8), and a second additional polariser (18) located on the light path, downstream of said liquid-crystal screen (8). The invention also relates to a head-up display (1) comprising a device (3) of this type.