Eyepiece with Movable Lens Groups for Variable Field of View
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Solution Overview
Problem
Existing VR and AR eyepieces struggle to provide optimal image quality and field of view across both wide and narrow angles, leading to image cropping and reduced pixel utilization, which affects user experience, especially in applications like movie watching and gaming.
Innovation Solution
A three-lens configuration with a movable positive lens group closest to the exit pupil, a stationary positive lens group closest to the image plane, and a movable negative lens group between them, allowing for variable field of view without cropping the image, thus utilizing the full display area and maintaining high image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a wide angle eyepiece with a single lens is used for VR projection, then the field of view is widened (115-95 degrees), but the image periphery is not resolved well enough and image quality suffers
Solution Approach 1:
The single lens is divided into multiple lens elements (first positive lens element, negative lens element, second positive lens element) arranged in sequence. This segmentation allows each element to contribute differently to the overall optical function, enabling wide field of view while maintaining image quality across the entire field including periphery regions.
Solution Approach 2:
Different lens elements have different optical properties tailored to specific regions of the field of view. The aspheric surfaces and varying refractive indices are designed to optimize light routing locally, ensuring that both central and peripheral areas of the display are resolved with high quality across the wide angular range.
2Measurement precision
If the field of view is cropped to improve image resolution, then the perceived resolution improves, but more than 50% of the display pixels are lost
Solution Approach 1:
The eyepiece dynamically adapts to different viewing conditions through its optical design that maintains high resolution across the entire wide field of view. This eliminates the need for static cropping, allowing the system to utilize 100% of display pixels while maintaining perceived resolution through proper optical routing and focal point management.
3Volume of moving object
If the eye-relief distance is reduced to make the headset more compact, then the device size is reduced, but the user experiences physical discomfort from eyelashes touching the eyepiece
Solution Approach 1:
The optical design allows for an increased eye-relief distance of at least 12mm without significantly increasing the overall headset volume. This is achieved through the specific arrangement and focal lengths of the lens elements, which optimize the optical path to provide both comfortable eye-relief and compact form factor.
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
Enables retention of pixel count across different field of view applications, reducing the display size while maintaining image quality, and providing a comfortable viewing experience by allowing the full display area to be used without distortion, even in peripheral areas.
Implementation Method 1
an eyepiece for use in a projection application, the eyepiece comprising a first positive lens group, a second negative lens group and a third positive lens group arranged in sequence from an image plane towards an exit pupil
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The invention relates to personal display devices and in particular an eyepiece therefor. The eyepiece is adapted for projecting an image from an image plane (14) on one side of the eyepiece through an exit pupil (10) on the opposite side of the eyepiece and comprises at least one stationary lens group (13) and at least two movable lens groups (11, 12) being movable with respect to the stationary lens group (13) along an optical axis between the image plane (14) and the exit pupil (10). According to the invention, the lens groups are arranged in positive-negative-positive configuration and the movable lens groups are arranged to move along the optical axis between a first state providing a first field- of-view and a second state providing a second field-of-view smaller than the first field-of-view to the image plane (14). The invention allows for improving optical performance and user experience of personal display devices.