HMD Eye Tracking via Variable Focal Length Lens Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current eye tracking technologies in head-mounted displays struggle with accuracy when measuring eye relief distance, especially when users gaze at distant objects, due to the use of flat 2D pupil images, leading to increased costs with the addition of multiple cameras to capture 3D information.
Innovation Solution
A head-mounted display apparatus with a distance measurement device that includes an image capturing device, a lens set, and a controller, which adjusts the position or focal length of the lens set at multiple time points to capture images of the target area, allowing for the calculation of the separation distance between the lens set and the eyeball, thereby improving eye tracking accuracy without the need for excessive hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple cameras are added to capture 3D eye relief information, then measurement precision of eye distance is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent changes the optical parameters of the existing single camera system by introducing a lens set with variable focal length. By adjusting the focal length parameter and capturing images at multiple focal length states, the system obtains sufficient information to calculate eye relief distance without adding multiple cameras, thus improving measurement precision while avoiding increased hardware complexity
Solution Approach 2:
The patent introduces a lens set as an intermediary component between the single camera and the target area. This lens set with variable focal length acts as a mediator that enables the single camera to capture images with different optical characteristics, providing enough data to compute 3D eye relief information without requiring multiple cameras
2Measurement precision
If multiple cameras are added to capture 3D eye relief information, then measurement precision of eye distance is improved, but manufacturing cost increases
Solution Approach 1:
The patent achieves improved eye distance measurement precision by changing the focal length parameter of the lens set rather than increasing the number of cameras. This parameter-based approach maintains manufacturing simplicity and lowers costs while still enabling accurate 3D eye relief calculation through multiple images captured at different focal length states
3Device complexity
If a single camera is used to capture 2D pupil images, then device complexity is reduced, but measurement precision of eye relief distance deteriorates
Solution Approach 1:
The patent introduces dynamics into the optical system by using a lens set with variable focal length. The focal length is dynamically adjusted to multiple different states, and images are captured at each state. This dynamic parameter change enables the single camera to gather sufficient information for accurate eye relief measurement while maintaining simple hardware architecture
Solution Approach 2:
The system performs periodic image capture at different focal length states of the lens set. By sequentially adjusting the focal length to multiple discrete states and capturing images at each state, the system accumulates enough data to calculate eye relief distance accurately, transforming a static single-camera system into a dynamic measurement system
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 measures eye distance and enhances eye tracking accuracy, reducing the need for additional cameras and lowering costs while maintaining display performance.
Implementation Method 1
The lens set has a first side facing the image capturing device and a second side facing a target area
Data Source
AI summary
A head mounted display apparatus and a distance measurement device are provided. The distance measurement device includes an image capturing device, a lens set, a position adjuster, and a controller. The position adjuster is configured to adjust positions of the image capturing device and the lens set. The position adjuster respectively adjusts the positions of the image capturing device and the lens set at a plurality of time points. The image capturing device respectively obtains a plurality of images of a target area at the plurality of time points. The controller accordingly obtains a separation distance between the lens set and the target area according to the plurality of images.