Projection Display Device Wavelength Control for HUD Brightness
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Solution Overview
Problem
Existing head-up display (HUD) systems face challenges in maintaining consistent image brightness across different incidence angles due to varying reflectance of hologram elements, leading to limited control over diffraction characteristics and increased manufacturing costs, and do not effectively address visibility issues when using hologram elements.
Innovation Solution
A projection display device and method that includes a projection angle control mechanism and an image light control unit, which adjusts the intensity of light in multiple wavelength ranges based on the projection angle using a wavelength selection film and light sources, ensuring consistent brightness regardless of the incidence angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a hologram element with high reflectance for multiple colors is used, then the brightness of virtual images can be maintained, but the design becomes complex and manufacturing cost increases
Solution Approach 1:
The patent divides the light control function into separate wavelength ranges by using multiple wavelength selection films (e.g., first wavelength selection film for blue light, second wavelength selection film for red light). Each film handles a specific wavelength range independently, avoiding the need for a single complex hologram element to manage all colors simultaneously. This segmentation simplifies the overall design while maintaining brightness across multiple colors.
Solution Approach 2:
The patent applies different reflectance characteristics to different wavelength ranges by positioning specific wavelength selection films in the optical path. Each wavelength range receives tailored optical treatment through its corresponding wavelength selection film, allowing optimized brightness control for each color without requiring the entire combiner design to be optimized for all colors at once.
2Illumination intensity
If the diffraction characteristic of the hologram element is controlled to maintain constant brightness, then visibility is improved, but control capability is limited and manufacturing cost increases
Solution Approach 1:
The patent introduces wavelength selection films as intermediary elements between the light source and the hologram element. These films selectively transmit or reflect specific wavelength ranges, acting as mediators that control which wavelengths reach the hologram element. This intermediary approach enables independent control of different color channels without requiring complex modifications to the hologram element's diffraction characteristics.
Solution Approach 2:
The patent enables dynamic control of brightness for different wavelength ranges by independently adjusting the properties of multiple wavelength selection films. Each film can be controlled separately to adapt to changing viewing conditions, projection angles, or display requirements, providing versatile control capability that overcomes the limitations of fixed diffraction characteristics in traditional hologram elements.
3Ease of manufacture
If a traditional windshield without hologram element is used, then manufacturing cost is reduced, but visibility control at different projection positions is poor
Solution Approach 1:
The patent creates a composite optical system by combining traditional windshield material with selectively positioned wavelength selection films. This composite structure maintains the simplicity and low cost of traditional windshields while adding targeted optical functionality through the wavelength selection films. The films are strategically placed to provide visibility control only where needed, rather than requiring the entire windshield to have complex holographic properties.
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 enhances image visibility by maintaining constant brightness across varying projection angles without complex hologram element design, reducing manufacturing costs and allowing flexible design options, while improving display quality and flexibility in HUD systems.
Implementation Method 1
a first wavelength selection film having a first reflectance for light in a first wavelength range and a first transmittance for light in a wavelength range other than the first wavelength range
Implementation Method 2
a first wavelength selection film having a first reflectance for light in a first wavelength range and a first transmittance for light in a wavelength range other than the first wavelength range
Implementation Method 3
a projection display unit that performs, in accordance with input image data, spatial modulation on light emitted by a light source
Implementation Method 4
projects image light obtained through the spatial modulation onto a projection surface of a vehicle to display an image
Data Source
AI summary
A projection display device has a projection display unit that performs, in accordance with input image data, spatial modulation on light emitted by a light source, and projects image light obtained through the spatial modulation onto a projection surface of a vehicle to display an image that is based on the image data, the projection surface is formed of a member having a reflectance that is higher for light in a plurality of wavelength ranges than for light in a wavelength range outside the plurality of wavelength ranges, and the projection display device includes: a projection angle control mechanism that controls a projection angle of the image light on the projection surface; and an image light control unit that controls, in accordance with the projection angle, intensity of the light in the plurality of wavelength ranges included in the image light.