Polarized Head-Up Display Optics for Brighter, Clearer Windscreen Images
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Solution Overview
Problem
The brightness of images projected on the windscreen in head-up display systems is reduced due to the transmission effect of the windscreen, which diminishes the display effect.
Innovation Solution
A head-up display system incorporating a display unit, a light splitting unit, a light-transmitting substrate, a first imaging unit, and a second imaging unit, where the light splitting unit converts light into first and second linearly polarized lights, and the imaging units reflect and transmit these polarized lights to enhance brightness and reduce ghosting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the windscreen transmits display light to project images, then the driver can view information without lowering the head, but the brightness of the projected image is reduced due to transmission loss
Solution Approach 1:
The patent applies polarization parameter changes to control light transmission and reflection. By using polarized light and polarization-selective reflective films, the system changes the optical parameters of light interaction with the windscreen, enabling high brightness projection while maintaining driver viewing convenience. The reflective polarizer selectively reflects polarized display light while allowing ambient light transmission, resolving the brightness loss issue.
Solution Approach 2:
The patent introduces a polarization-selective reflective film as an intermediary element between the display light source and the windscreen. This intermediary selectively reflects polarized display light to enhance brightness while maintaining windscreen transparency for ambient light, thus resolving the contradiction between image brightness and viewing convenience.
2Illumination intensity
If multiple reflections occur between windscreen surfaces, then light can be redirected to the driver's eye, but ghosting phenomena occur due to multiple imaging paths
Solution Approach 1:
The patent applies local quality by making the reflective film polarization-selective rather than uniformly reflective. The film reflects only polarized display light while allowing non-polarized ambient light to pass through, creating different optical properties for different light types at the same location. This eliminates ghosting by ensuring only the desired light path is reflected.
Solution Approach 2:
The patent changes the polarization parameter of light to control reflection and transmission. By converting display light to polarized light and using a polarization-selective reflective film, the system creates a single reliable imaging path while blocking multiple reflection paths that cause ghosting, thus improving image clarity.
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
Improves light utilization, reduces energy consumption, and enhances the display effect by increasing the brightness and contrast of images projected on the windscreen, allowing for clearer viewing of both the displayed content and the external environment.
Implementation Method 1
a light splitting unit, disposed on a light emitting side of the display unit, and configured to transmit a first linearly polarized light and block a second linearly polarized light, wherein light emitted by the display unit is converted into the first linearly polarized light after passing through the light splitting unit
Implementation Method 2
the first imaging unit includes a transflective film disposed on an optical path from the light splitting unit to the light-transmitting substrate. The transflective film is configured to reflect a part of the first linearly polarized light and transmit a remaining part of the first linearly polarized light
Implementation Method 3
The phase retarder is configured to convert the first linearly polarized light into the second linearly polarized light on an optical path from the light-transmitting substrate to the second reflective polarizer; and to convert the second linearly polarized light into the first linearly polarized light on an optical path from the second reflective polarizer to the light-transmitting substrate
Data Source
AI summary
A head-up display system and a display apparatus are provided in this disclosure, which relates to a technical field of displaying. The head-up display system includes a display unit; a light splitting unit provided on a light emitting side of the display unit and configured to transmit a first linearly polarized light and block a second linearly polarized light, light emitted by the display unit being converted into the first linearly polarized light after passing through the light splitting unit; a light-transmitting substrate; a first imaging unit provided on an optical path from the light splitting unit to the light-transmitting substrate and configured to be able to transmit and reflect the first linearly polarized light; and a second imaging unit provided on a side of the light-transmitting substrate away from the first imaging unit, and configured to reflect the first linearly polarized light transmitted through the light-transmitting substrate.