Compact Eye-Tracking Camera With Compound Mirror
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Solution Overview
Problem
The integration of eye-tracking systems into thin displays, such as modern laptops and tablets, is challenging due to the irreducible minimum focal length of lenses and cameras, which often exceeds the display thickness, leading to undesirable non-flush configurations and manufacturability issues.
Innovation Solution
A compact eye-tracking camera assembly is implemented with a laterally-mounted lens and image sensor, utilizing a compound mirror oriented at a 45-degree angle relative to one axis and 15-22 degrees relative to another axis parallel to the display surface, allowing the camera assembly to be incorporated into thinner displays while maintaining effective IR light collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional lens and camera assembly are used for eye-tracking, then the system can accurately capture reflected images of the user's face, but the minimum focal length (15 mm or more) exceeds the display thickness, resulting in non-flush configurations
Solution Approach 1:
The patent changes the mounting orientation of the camera assembly from a conventional approach (where the optical axis is perpendicular to the display surface) to a lateral mounting configuration where the optical axis is parallel to the display surface. This dimensional change allows the camera to be positioned within the thin display structure while maintaining its focal length requirements, achieving flush integration without compromising eye-tracking accuracy.
Solution Approach 2:
The patent introduces a compound angle mirror as an intermediary optical element that redirects infrared light from the user's face along the principal axis of the camera assembly. This mediator enables the camera to capture images effectively despite the lateral mounting configuration and thin display thickness, resolving the contradiction between maintaining measurement precision and reducing device length.
2Length of stationary object
If the camera assembly is mounted flush with the display surface, then the device thickness is reduced, but the lens focal length requirements cannot be met
Solution Approach 1:
By reorienting the camera assembly to a lateral mounting configuration where the optical axis is parallel to the display surface rather than perpendicular, the patent enables flush integration within thin displays while satisfying the lens focal length requirements. This dimensional reconfiguration allows the camera to be positioned within the display structure without compromising manufacturability or optical performance.
Solution Approach 2:
The compound angle mirror serves as an intermediary that enables the camera assembly to function effectively in a flush-mounted configuration. It redirects infrared light along the camera's principal axis, allowing the system to meet focal length requirements while achieving thin-profile integration, thus improving ease of manufacture for thin display devices.
3Length of stationary object
If a compound angle mirror is used to redirect IR light, then the camera assembly can be mounted laterally for flush integration, but the optical path becomes more complex
Solution Approach 1:
The compound angle mirror is introduced as a specialized intermediary optical element that efficiently redirects infrared light from the user's face along the camera assembly's principal axis. This mediator enables lateral mounting for flush integration while managing optical path complexity through a well-defined reflection geometry, balancing device thickness reduction with optical system feasibility.
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 solution reduces the required thickness of devices by up to 50% by mounting the camera assembly parallel to the display and using a compound angle mirror to redirect IR light, enabling flush integration of eye-tracking functionality into thin computing devices.
Implementation Method 1
a compound mirror generally oriented toward a user's face... a compound angle mirror configured to redirect incident IR light along the principal axis
Data Source
AI summary
Systems and methods are provided for a compact eye-tracking camera assembly. The camera incorporates a lens and image sensor whose principal axis is parallel to the plane of the display surface, and a compound angle mirror configured to redirect incident IR light along the principal axis. The compound angle mirror has a first angle of approximately 45 degrees relative to a first axis, and a second angle of approximately 15-22 degrees (e.g., 18 degrees) relative to a second axis that is orthogonal to the first axis. The first and second axes are substantially parallel to the plane of the display surface.