Diffraction Elements and Mirror for Luminance Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing display devices with diffraction elements on both sides of a light-guiding member face challenges in maintaining image quality due to luminance unevenness, which can be exacerbated by the addition of optical members to adjust incident and exit angles, leading to increased system size.
Innovation Solution
A display device incorporating a first diffraction element with positive power at the incident side, a second diffraction element with positive power at the exit side, and a mirror with positive power at the incident side of the light-guiding member, where the image light is reflected and propagated to form an exit pupil, allowing for wavelength compensation and reduced luminance unevenness without increasing the system's thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mirror or another optical member having positive power is added to suppress luminance unevenness, then image quality is improved, but the size of the optical system increases
Solution Approach 1:
The patent combines the functions of multiple optical elements into an integrated configuration. The first diffraction element, second diffraction element, and mirror are arranged in a compact sequence where the mirror reflects light back through the light-guiding member, allowing the system to achieve luminance correction without adding significant volume. The diffraction elements are positioned at specific locations (incident side and exit side) to work synergistically with the mirror.
Solution Approach 2:
The patent utilizes the optical path length rather than physical space by folding the light path with the mirror. Instead of adding optical members in a linear extension, the mirror reflects light back through the existing light-guiding member, effectively using the same physical space multiple times to achieve the desired optical effect without increasing system volume.
2Adaptability or versatility
If diffraction elements are added to adjust incident and exit angles, then flexibility in setting inclination is improved, but device complexity increases
Solution Approach 1:
The patent employs diffraction elements with specific diffraction characteristics that can be adjusted by changing their optical parameters. The first and second diffraction elements are designed with positive power and specific diffraction angles that allow independent adjustment of incident and exit angles. This enables flexible inclination setting without requiring complex mechanical adjustment mechanisms.
Solution Approach 2:
The patent replaces mechanical adjustment mechanisms with optical diffraction elements. Instead of using movable mirrors or adjustable lenses to change incident and exit angles, the system uses diffraction elements that inherently provide angular control through their diffraction properties, simplifying the overall device structure.
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 image light deterioration and luminance unevenness while maintaining a compact design by ensuring the diffraction elements are conjugate and the mirror is positioned to control light beam incidence, preventing the light-guiding plate from becoming thick and the second diffraction element from being overly large.
Implementation Method 1
a first diffraction element provided at an incident side of the light-guiding member and having positive power
Implementation Method 2
the image light that passed through the first diffraction element is reflected by the mirror
Implementation Method 3
the image light incident on the second diffraction element is deflected by the second diffraction element forming an exit pupil
Data Source
AI summary
A display device includes an image light generating device, a light-guiding member on which image light emitted from the image light generating device is incident, a first diffraction element provided at an incident side of the light-guiding member and having positive power, a second diffraction element provided at an exit side of the light-guiding member and having positive power, and a mirror provided at an end portion at the incident side of the light-guiding member and having positive power, in which the image light passed through the first diffraction element is reflected by the mirror and propagates in the light-guiding member, and the image light incident on the second diffraction element is deflected by the second diffraction element forming an exit pupil.