Head-Up Display Using Polarized Light Combiner
Solution Overview
Problem
Current head-up displays face issues with fragility, high power consumption, heat generation, and insufficient luminance, particularly when using cathode ray tube (CRT) sources, and flat panel liquid crystal displays (LCDs) have not achieved widespread success due to luminance challenges.
Innovation Solution
The solution involves a head-up display apparatus that uses a data image display with a backlight, liquid crystal layer, and polarizers oriented to deliver s-polarized light to a combiner, which selectively reflects s-polarized light while transmitting background scenes, enhancing luminance and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If CRT image sources are used in head-up displays, then the display can provide sufficient luminance, but the device becomes fragile, bulky, and consumes more power
Solution Approach 1:
The patent changes the fundamental parameters of the display system by introducing a polarizing beamsplitter combiner and s-polarized LCD technology. This allows the system to achieve high luminance efficiency (above 50%) while using a compact, reliable LCD source instead of a bulky CRT, directly resolving the contradiction between luminance performance and device reliability/compactness
Solution Approach 2:
The patent replaces the electro-mechanical CRT system with an optical-based LCD system combined with a polarizing beamsplitter. This substitution eliminates the fragile electron gun and phosphor screen of CRTs while maintaining sufficient luminance through the optical polarization and beam-splitting mechanism
2Reliability
If conventional LCD technology is used in head-up displays, then the device becomes more compact and reliable, but sufficient luminance cannot be achieved
Solution Approach 1:
The patent introduces a polarizing beamsplitter combiner as an intermediary optical element between the LCD source and the viewer's eye. This beamsplitter mediates the light path by reflecting s-polarized light from the LCD toward the viewer while allowing p-polarized ambient light to pass through, thereby amplifying the effective luminance of the LCD display without requiring a brighter (and more power-consuming) LCD source
Solution Approach 2:
The patent changes the optical parameters of the system by utilizing polarization states (s-polarization vs. p-polarization) to control light transmission and reflection. This allows conventional LCDs to achieve sufficient display luminance through the polarizing beamsplitter mechanism without needing to increase their backlight power consumption
3Adaptability or versatility
If a combiner is used to superimpose data and background images, then head-up display functionality is achieved, but light leakage and reduced optical efficiency occur
Solution Approach 1:
The patent applies local quality by making the combiner's optical properties polarization-dependent. The polarizing beamsplitter has different transmission and reflection characteristics for s-polarized and p-polarized light, allowing it to efficiently direct data image light (s-polarized) to the viewer while permitting background scene light (p-polarized) to pass through with minimal loss, thereby reducing optical energy waste
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
This approach provides improved luminance and optical efficiency, reducing power consumption and heat, while maintaining binocular symmetry and minimizing light leakage, resulting in a more effective and user-friendly head-up display.
Implementation Method 1
The data image display preferentially delivers s-polarized light to the combiner, which has a selective reflectance region for preferentially reflecting s-polarized light toward the viewer
Implementation Method 2
selectively reflecting the s-polarized data image off the combiner towards the viewer while transmitting the background scene image through the combiner
Implementation Method 3
A data image display comprises a backlight, a liquid crystal layer and two polarizers oriented so that the data images directed toward the combiner are s-polarized with respect to the selective reflectance region
Data Source
AI summary
Methods and apparatus are provided for a combined image on a head-up display. A data image display provides a first part of a combined image. An optical input provides a second part of the combined image, e.g., the background scene. A combiner superimposes the first and second parts to provide the combined image to the viewer. The data image display preferentially delivers s-polarized light to the combiner, which has a selective reflectance region for preferentially reflecting s-polarized light in a wavelength region of interest. In a preferred embodiment, the data image display comprises a backlight, a liquid crystal layer and two polarizers oriented so that the data images directed toward the combiner are s-polarized with respect to the selective reflectance region. A polarization rotation element may also be used in the data image display to facilitate s-polarization orientation.