Overlapping Diffraction Elements for Compact Head-Mounted Display Exit Pupil
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing head-mounted image display devices require a large number of laser light sources to expand the exit pupil, leading to increased device size and the need for complex CPU processing to compensate for image light distortion, which further complicates the device configuration.
Innovation Solution
An image display device with a deflection member comprising overlapping reflective diffraction elements, utilizing a combination of first and second light sources with different wavelength bands, and a combining optical member to generate and superimpose image light, effectively expanding the exit pupil without increasing device size or requiring large-scale CPU processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a large number of laser light sources are used to expand the exit pupil, then the exit pupil size is improved, but the device size increases
Solution Approach 1:
The patent combines multiple light sources (first light source emitting first wavelength and second light source emitting second wavelength) into a single integrated structure. The combining optical member superimposes the light from both sources, allowing multiple pupils to be generated simultaneously without requiring separate physical spaces for each light source, thus expanding the exit pupil while maintaining compact device size.
Solution Approach 2:
The patent utilizes the wavelength dimension to differentiate and multiplex multiple light sources. By assigning different wavelength bands to different light sources and using wavelength-selective diffraction elements, the system can generate multiple pupils in the spatial domain simultaneously, effectively expanding the exit pupil without increasing the physical footprint of the device.
2Area of moving object
If multiple light sources are used to generate multiple pupils, then the exit pupil size is improved, but the device complexity increases
Solution Approach 1:
The deflection member is designed with multiple diffraction elements that serve multiple functions simultaneously. Each diffraction element is configured to diffract light of a specific wavelength band to form a pupil at a specific position. This multi-functional design allows a single deflection member to generate multiple pupils for different wavelength sources without requiring separate deflection mechanisms, thereby reducing device complexity while maintaining expanded exit pupil capability.
3Area of moving object
If incident angle of image light varies for multiple pupils, then the exit pupil size is improved, but image distortion increases
Solution Approach 1:
The patent implements local quality by configuring each diffraction element with specific diffraction characteristics tailored to its corresponding wavelength band and target pupil position. Each diffraction element is designed to compensate for the specific incident angle variations and distortion characteristics of its associated light path, ensuring that image quality is maintained locally for each pupil while the overall system provides multiple expanded pupils.
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 efficiently expands the exit pupil size while preventing distortion and reducing the need for complex processing, thereby maintaining a compact device configuration and improving image display quality.
Implementation Method 1
a deflection member of a reflective-type configured to deflect the image light emitted from the image light generation device
Implementation Method 2
the deflection member includes a first diffraction member including a first diffraction element corresponding to the wavelength band of the first light and a second diffraction member including a second diffraction element corresponding to the wavelength band of the second light
Implementation Method 3
a combining optical member configured to at least partially superimpose the first light and the second light
Data Source
AI summary
An image display device includes an image light generation device configured to generate image light, and a deflection member configured to deflect the image light to form an exit pupil, in which the image light generation device includes a first light source unit configured to emit first light, a second light source unit configured to emit second light within a same frequency band as the first light and having a wavelength band different from a wavelength band of the first light, and a combining optical member configured to at least partially superimpose the first light and the second light, the deflection member includes a first diffraction member corresponding to the wavelength band of the first light and a second diffraction member corresponding to the wavelength band of the second light, and the first diffraction member and the second diffraction member overlap when viewed from the exit pupil.