Pinhole Placement for Eye Tracking in Head-Mounted Displays
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Solution Overview
Problem
Existing head-mounted displays face challenges in accurately tracking eye movements due to optical path disruptions from other components, leading to poor imaging of light beams onto image sensors, which affects the clarity and accuracy of eye tracking.
Innovation Solution
A head-mounted display design incorporating a pinhole positioned outside the space defined by the display and first lens, allowing light beams reflected from the eye to form clear images on image sensors, regardless of varying distances, and utilizing additional lenses and a processing unit for enhanced eye tracking functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the eye tracking element is integrated into the head-mounted display, then the viewing angle can be expanded and three-dimensional scene tracking is enabled, but the optical path of the light beam is easily affected by other members of the display, causing poor imaging on the image sensor
Solution Approach 1:
The patent divides the optical path into separate segments: one for display (through the first lens) and one for eye tracking (through the pinhole). By positioning the pinhole outside the space defined by the display and first lens, the eye tracking optical path is segmented from the display optical path, preventing interference between the two functions while maintaining both capabilities.
Solution Approach 2:
The pinhole acts as an intermediary element that selectively transmits light beams from the eye ball to the image sensor while being positioned outside the display optical path. This intermediary structure enables eye tracking functionality without being affected by the display components, solving the interference problem.
2Device complexity
If the pinhole is positioned inside the space defined by the display and first lens, then the structure is more compact, but the light beam is deflected by the first lens, causing poor imaging on the image sensor
Solution Approach 1:
The pinhole is extracted from the interior space defined by the display and first lens, and positioned outside this space. This extraction removes the pinhole from the interference zone of the display optical path, eliminating lens deflection effects while maintaining a relatively compact overall structure.
3Illumination intensity
If the light source is positioned close to the eye ball, then the illumination is more direct, but the light beam is easily blocked by other members of the head-mounted display
Solution Approach 1:
The patent positions the light source in a dimension outside the space defined by the display and first lens, similar to the pinhole positioning. This dimensional separation allows the light source to illuminate the eye ball directly without being blocked by display members, as the light path operates in a separate spatial dimension.
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
This design ensures clear imaging of eye features for effective eye tracking, reduces stray light, and enhances flexibility in design by preventing light beam deflection and improving focal length issues, resulting in a more reliable and flexible eye tracking system.
Implementation Method 1
The at least one pinhole is disposed outside a space defined by the display and the first lens. The at least one light beam reflected by the eye ball passes through the at least one pinhole to form an image on the at least one image sensor.
Implementation Method 2
magnifying lenses are adopted to adjust optical paths, such that images may be projected to the eyes within a short distance
Implementation Method 3
The at least one light source emits at least one light beam to illumine an eye ball of the user. The at least one light beam reflected by the eye ball passes through the at least one pinhole to form an image on the at least one image sensor.
Data Source
AI summary
A head-mounted display including a display, a first lens, at least one light source, at least one pinhole and at least one image sensor is provided. An eye ball observes the display by the first lens. The at least one light source emits at least one light beam to illumine the eye ball. The at least one pinhole is disposed outside a space between the display and the first lens. The at least one light beam reflected by the eye ball passes through the at least one pinhole to form an image on the at least one image sensor.