Eccentric Lens Unit and Microlens Array for HMD Angle of View
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Solution Overview
Problem
There is a need for a technique to present an enlarged image to a user in a head part fitting type display, such as a head-mounted display, while maintaining high resolution and avoiding image blurring over the entire angle of view.
Innovation Solution
An image display apparatus comprising a first lens unit, a second lens unit, and a microlens array, where the second lens unit is eccentrically positioned relative to the first lens unit, and a light emitting unit, such as a spatial light modulator or microdisplay, controls light to be refracted by the microlens array to achieve an enlarged angle of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If an eyepiece optical system is used to enlarge the display image, then the angle of view is enlarged, but field curvature causes image blurring over the entire angle of view
Solution Approach 1:
A field curvature correction optical system is introduced as an intermediary between the eyepiece optical system and the transmissive display element. This intermediate system specifically addresses the field curvature issue by redirecting light rays to compensate for the curved focal surface, thereby maintaining image sharpness across the entire enlarged angle of view without requiring changes to the eyepiece design itself.
Solution Approach 2:
The optical system is divided into distinct functional segments: the eyepiece optical system for magnification, the field curvature correction optical system for maintaining image quality, and the transmissive display element for image generation. This segmentation allows each component to be optimized independently, with the correction system specifically addressing the field curvature problem caused by the eyepiece.
2Manufacturing precision
If a diffusion optical element is used to compensate field curvature, then image resolution is maintained, but the system complexity increases
Solution Approach 1:
The field curvature correction function is extracted from the eyepiece optical system itself and implemented as a separate, dedicated optical system. This extraction allows the correction mechanism to be independently optimized and positioned at the most effective location in the optical path, while the eyepiece can focus solely on providing magnification.
3Area of moving object
If the second lens unit is positioned farther from the eye, then the angle of view is enlarged, but the distance between lens units increases
Solution Approach 1:
The optical design utilizes eccentric positioning of the second lens unit relative to the first lens unit, introducing a lateral offset in addition to the axial distance. This dimensional change allows the system to achieve a larger angle of view by positioning the second lens unit farther from the eye while managing the overall compactness through strategic lateral placement rather than simply increasing axial separation.
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 apparatus provides an enlarged image with improved resolution and reduced blurring by converting light into parallel or divergent light, allowing for a larger angle of view and addressing the challenge of presenting clear images to users.
Implementation Method 1
The microlens array is disposed at a first conjugate position based on the first lens unit and the second lens unit... The light emitting unit controls light that enters the microlens array by changing an emission position or emission direction of the light
Implementation Method 2
a first lens unit, a second lens unit, and a microlens array... The microlens array is disposed at a first conjugate position based on the first lens unit and the second lens unit
Implementation Method 3
The second lens unit may convert light refracted by the first lens unit into divergent light... The second lens unit may convert light refracted by the first lens unit into substantially parallel light
Data Source
AI summary
An image display apparatus of the present technology includes a first lens unit (70), a second lens unit (80), and a microlens array (50). The second lens unit (80) eccentrically faces the first lens unit (70). The microlens array (50) is disposed at a first conjugate position (K1) based on the first and second lens units (70, 80).