HMD Tracking Pixels for Eye Orientation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional head-mounted displays (HMDs) with active eye tracking require additional illumination sources that increase size and complexity, posing challenges in minimizing size, weight, and power consumption while maintaining effective eye tracking capabilities.

Innovation Solution

Integration of tracking pixels within the display element that emit light for eye tracking, either separately from or concurrently with content pixels, allowing for efficient use of existing display infrastructure and optics to determine eye orientation using structured or quasi-uniform illumination patterns, with control over illumination timing to minimize user noticeability and stray light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional illumination sources are added for active eye tracking, then eye tracking capability is improved, but device size and complexity increase

Engineering Contradiction:

Improveeye tracking capabilityVSAvoidHMD structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the illumination function with the display function by using display pixels to emit tracking light. The display element serves dual purposes: presenting visual content to the user and providing illumination for eye tracking, thereby eliminating the need for separate illumination sources and reducing overall device complexity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The display pixels are designed to perform multiple functions: they display visual content during normal operation and emit tracking light for eye tracking. This multi-functionality allows the same hardware components to serve both display and illumination purposes, reducing the number of required components

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Illumination intensity

If tracking pixels operate at high duty-cycle, then illumination signal strength is improved, but eye safety limits may be exceeded and stray light increases

Engineering Contradiction:

Improvetracking light intensityVSAvoideye safety and stray light

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The tracking pixels operate using periodic pulsed illumination rather than continuous emission. By controlling the duty cycle of the tracking pixels to match the display refresh rate, the system achieves sufficient illumination signal strength while limiting total energy exposure to safe levels and reducing stray light through synchronized timing

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts the illumination parameters by synchronizing tracking pixel activation with the display refresh cycle. This dynamic control allows optimization of signal strength at specific moments while maintaining safety limits through temporal distribution of illumination energy

Inventive Principle:

Principle #15Dynamics

3Ease of operation

If tracking pixels are separate from content pixels, then tracking light control is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvetracking light controlVSAvoiddisplay element fabrication

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The patent implements local quality by enabling specific regions or individual pixels within the display element to emit tracking light while other pixels display content. This selective emission capability provides precise tracking light control while maintaining a unified display structure that is easier to manufacture than completely separate pixel arrays

Inventive Principle:

Principle #3Local quality

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 compact, power-efficient HMDs with accurate eye tracking, reducing size and weight while maintaining high refresh rates and minimizing user perception of tracking operations, thereby enhancing user experience and system performance.

Implementation Method 1

The one or more tracking pixels emit light in the IR band. The tracking pixels emitting IR light may be turned on during all times of a time period in a given image frame.

Methodology Applied

Scientific EffectLight emission from pixels: Light Emitting Diode

Implementation Method 2

The camera captures one or more images of an eye of the user in response to projected tracking light on the eye, where the one or more captured images include an illuminated profile of the eye

Methodology Applied

Scientific EffectLight reflection and detection: Reflection

Data Source

PatentUS10152121B2Eye tracking through illumination by head-mounted displays

Publication Date: 2018.12.11 META PLATFORMS TECHNOLOGIES LLC

AI summary

A head-mounted display (HMD) presents content for viewing by users. The HMD includes a display element, an optics block, and a camera. The display element includes content pixels for providing light corresponding to the displayed content and one or more tracking pixels for providing tracking light used for tracking the user's eye movements. The optics block directs light from the display element (light corresponding to the displayed content and that of tracking light) to an exit pupil of the HMD. The camera captures one or images of an eye of the user in response to projecting tracking light on the eye, where the one or more captured images include a distortion of the projected tracking light and are used in determining an orientation of the eye at a time of capturing the one or more images of the eye.