Head-Up Display Optics With Dual Diffusion to Suppress Stripe Patterns
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Solution Overview
Problem
Conventional head-up displays using Fresnel lenses suffer from a visually identifiable striped pattern due to microstructures, which reduces the luminance of the display light.
Innovation Solution
Incorporating a first and second diffusion structure spaced apart, each with low haze values, and an optical member with refractive optical elements to diffuse and refract basal light, reducing the visibility of the striped pattern while maintaining luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a Fresnel lens is used to render luminance uniform, then the luminance uniformity is improved, but a striped pattern becomes visually identifiable reducing image quality
Solution Approach 1:
The patent divides the single optical member into multiple optical elements (first optical element and second optical element) with different microstructure configurations. The first optical element has a first microstructure and the second optical element has a second microstructure, segmenting the light diffusion function to reduce the striped pattern while maintaining luminance uniformity.
Solution Approach 2:
Different regions of the optical system are assigned different microstructure properties. The first optical element and second optical element have different microstructure designs, allowing each region to contribute differently to the overall light diffusion, thereby eliminating the striped pattern while maintaining uniform luminance across the display.
2Object-affected harmful factors
If the microstructure pitch is reduced to lower striped pattern visibility, then the striped pattern becomes less visible, but the luminance of display light is reduced
Solution Approach 1:
Instead of uniformly reducing the microstructure pitch across the entire optical system, the patent segments the optical system into multiple elements with different microstructure pitches and configurations. This allows the striped pattern to be reduced without uniformly sacrificing luminance across all optical paths.
Solution Approach 2:
The optical system uses a composite configuration of multiple optical elements with different microstructure properties. By combining optical elements with different microstructure characteristics, the system achieves reduced striped pattern visibility while maintaining overall luminance through the composite optical path.
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 minimizes the visibility of the striped pattern and maintains the luminance of the display light, enhancing the quality of the virtual image.
Implementation Method 1
a first diffusion structure that diffuses the basal light that is to enter the display panel
Implementation Method 2
a second diffusion structure that is disposed spaced apart from the first diffusion structure, and diffuses the basal light that is to enter the first diffusion structure
Implementation Method 3
an optical member that includes a plurality of optical elements each of which refracts the basal light that is to enter the second diffusion structure
Implementation Method 4
a mirror that reflects the display light that exits from the display panel
Data Source
AI summary
A display device is a display device that includes a display panel from which display light showing an image exits and a light source that emits basal light for producing the display light. The display device includes: a first diffusion sheet that diffuses the basal light that is to enter the display panel; a second diffusion sheet that is disposed spaced apart from the first diffusion sheet, and diffuses the basal light that is to enter the first diffusion sheet; and an optical member that includes a plurality of optical elements each of which refracts the basal light that is to enter the second diffusion sheet.