Diffraction Optical Element Groups for Display Color Shift Correction
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Solution Overview
Problem
Existing display devices using holograms for image light guidance face issues with image quality due to color shifts and reduced brightness caused by separating holograms with positive power, leading to decreased observed image quality.
Innovation Solution
A display device employing a first and second diffraction optical element group with reflection-type volume holograms, where each group is laminated with specific interference patterns corresponding to two or fewer colors, positioned to minimize color shifts and maintain high brightness by efficiently diffracting and directing image light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If holograms with positive power are disposed separated from each other, then the projection optical system can be simplified, but the projection position of image light shifts for each color leading to decreased image quality
Solution Approach 1:
The patent divides the hologram into multiple diffraction optical element groups, with each group containing multiple diffraction optical elements having different interference patterns. This segmentation allows each element to handle specific wavelength bands separately, preventing color shift while maintaining a compact optical system structure.
Solution Approach 2:
Each diffraction optical element within the groups has a specific interference pattern tailored to its function - some elements have patterns corresponding to specific wavelength bands (red, green, blue) while others have patterns for different bands. This local specialization ensures that each element optimally processes its designated wavelength range without causing color shift.
2Ease of operation
If holograms are separated to guide image light, then the light guiding function is achieved, but brightness reduction and color shifts occur
Solution Approach 1:
The patent combines multiple diffraction optical elements with different interference patterns into integrated groups. By merging these elements in close proximity rather than separating them widely, the system maintains efficient light guidance while preserving brightness and preventing color shift through coordinated diffraction action.
3Measurement precision
If multiple diffraction optical elements are used with different interference patterns, then wavelength compensation is improved, but device complexity increases
Solution Approach 1:
Each diffraction optical element group serves multiple functions: it diffracts light for its specific wavelength band, compensates for color shift, and contributes to the overall image guidance. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in device complexity.
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 suppresses color shifts and brightness reduction, enhancing image quality by ensuring accurate wavelength compensation and maintaining high luminous sensitivity, particularly for green light, which is crucial for visibility.
Implementation Method 1
a first diffraction optical element group having positive power and configured to receive the image light, and a second diffraction optical element group having positive power and configured to diffract the image light diffracted by the first diffraction optical element group to form an exit pupil
Data Source
AI summary
The display device including a first diffraction optical element group, and a second diffraction optical element group, wherein the first diffraction optical element group is constituted by laminating a first diffraction optical element having a first interference pattern corresponding to a wavelength band of one or two of three colors of red, green, and blue of the image light, and a second diffraction optical element having a second interference pattern corresponding to a wavelength band of remaining colors of the three colors, and the second diffraction optical element group is constituted by laminating a third diffraction optical element having a third interference pattern corresponding to a wavelength band of one or two of three colors of red, green, and blue of the image light, and a fourth diffraction optical element having a fourth interference pattern corresponding to a wavelength band of remaining colors of the three colors.