HMD Eye Tracking With Photodetector Arrays and Temperature Compensation
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Solution Overview
Problem
Existing eye tracking systems in head-mounted display units face challenges such as high cost, complexity, weight, energy consumption, heat emission, and computing power requirements, particularly in mobile standalone devices.
Innovation Solution
A low-power eye tracking system for HMD units utilizing a support frame with a light source, photosensors, temperature sensors, and a processor that compensates for measurement errors due to variable operating temperature through a calibration procedure and temperature compensation algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If IR cameras are used for eye tracking, then tracking accuracy is improved, but device weight and power consumption increase
Solution Approach 1:
The patent extracts the eye tracking functionality from complex IR camera systems and implements it using a simplified photodetector array that directly detects eye position without requiring full camera imaging, thereby reducing weight while maintaining tracking accuracy
Solution Approach 2:
The patent uses a photodetector array that captures light reflected from the eye, creating a simplified optical copy of eye position information without needing full imaging capability, thus achieving accurate tracking with reduced hardware weight
2Measurement precision
If IR cameras are used for eye tracking, then tracking accuracy is improved, but power consumption increases
Solution Approach 1:
The patent extracts only the essential eye position detection function from full IR camera systems, using photodetectors that consume significantly less power while maintaining tracking accuracy through direct light detection rather than full image processing
Solution Approach 2:
The patent employs inexpensive photodetector elements with low power requirements instead of expensive, high-power IR cameras, accepting that the simpler sensors need frequent calibration but achieving overall system efficiency through reduced power consumption
3Measurement precision
If IR cameras are used for eye tracking, then tracking accuracy is improved, but device complexity increases
Solution Approach 1:
The patent removes the complex optical path requirements including IR mirrors and complex lens systems from the eye tracking module, retaining only the essential photodetector array that can directly detect eye position with simpler assembly
Solution Approach 2:
The patent integrates the photodetector array into the existing HMD display structure, allowing the display optics to serve dual purposes for both image delivery and eye tracking, thereby reducing overall system complexity
4Device complexity
If photosensors are used without temperature compensation, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent incorporates temperature sensors that continuously monitor the photosensor temperature and feeds this information back to a processor that compensates for temperature-induced measurement drift, maintaining gaze position accuracy without significantly increasing system complexity
Solution Approach 2:
The patent changes the operational parameters of the photosensors by applying temperature-based calibration adjustments, compensating for temperature drift effects on measurement precision through software algorithms that adjust sensor responses based on measured temperature
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 system achieves accurate gaze position estimation with reduced power consumption, simplified assembly, and improved user experience by minimizing errors and reducing the need for additional cooling systems.
Implementation Method 1
a plurality of photosensors mounted to the support frame and configured to receive reflected light from different portions of the illuminated eye
Implementation Method 2
a temperature sensor mounted to the support frame and configured to measure a temperature of the photosensors
Data Source
AI summary
A virtual reality/augmented reality (VR/AR) wearable assembly is described herein. The VR/AR wearable assembly includes a support frame, a display mounted to the support frame, a plurality of light emitters configured to illuminate an area of a subject's eye, a plurality of photosensors configured to receive reflected light from different portions of the illuminated subject's eye, and a controller operatively coupled to the display, the plurality of light emitters, and the plurality of photosensors. The controller includes a processor programmed to execute an algorithm including the steps of alternating illumination of the light emitters to generate predefined lighting patterns, acquiring data from the plurality of photosensors when corresponding light emitters are illuminated, mapping intensities of reflected light based on the acquired data from the plurality of photosensors, and determining a gaze position of the subject's eye based on the mapped intensities of reflected light.