Calibration Frames for Accurate Pupillary Distance Measurement
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Solution Overview
Problem
Current methods for measuring pupillary distance (PD) are inaccurate, costly, and difficult to use, especially for self-administered measurements, often resulting in errors due to parallax issues and the inability to distinguish between near and far PD, which is crucial for proper eyeglass prescription and virtual reality headset alignment.
Innovation Solution
The use of calibration frames with known markings on eyeglass frames that serve as an absolute reference, combined with image processing on a personal electronic device, to accurately measure PD by detecting the calibration marks and pupil centers, accounting for vergence and providing options for manual adjustments to ensure precise calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If self-administered PD ruler measurements are used, then cost is reduced, but measurement precision deteriorates due to parallax errors and inability to distinguish near and far PD
Solution Approach 1:
The patent introduces a camera as an intermediary device to capture images of the user's eyes and a reference object. This intermediary enables automated PD measurement by processing the captured images through image recognition algorithms, eliminating the need for manual ruler measurement while maintaining accessibility and low cost.
Solution Approach 2:
The patent replaces the mechanical PD ruler system with an optical-digital system using a camera to capture images and software to calculate PD. This substitution eliminates parallax errors inherent in manual ruler measurement while keeping the solution affordable and easy to use through smartphone integration.
2Device complexity
If credit card reference method is used in PD apps, then device complexity is reduced, but measurement precision deteriorates due to parallax errors exceeding 1 mm
Solution Approach 1:
The patent introduces specialized calibration objects with known geometric features as intermediaries between the camera and the measurement target. These calibration objects provide reference scales and alignment markers that enable the system to compensate for camera angle and distance variations, achieving sub-millimeter accuracy.
Solution Approach 2:
The patent changes the reference from a flat credit card to three-dimensional calibration objects with known spatial parameters. These objects provide multiple reference points at different depths and angles, enabling the system to calculate and correct for parallax errors through geometric relationships.
3Ease of operation
If manual PD measurement methods are used, then ease of operation is improved, but measurement precision deteriorates due to user alignment errors
Solution Approach 1:
The patent enables the measurement system to perform self-alignment by automatically detecting the user's eyes and the calibration object in captured images. The software identifies key features and calculates PD without requiring manual positioning or alignment by the user, eliminating alignment errors while maintaining ease of use.
Solution Approach 2:
The patent incorporates feedback mechanisms where the system captures images, processes them to detect eye positions and calibration markers, and automatically adjusts calculations based on detected parameters. This closed-loop approach eliminates manual alignment errors by using real-time image feedback for automated measurement.
4Measurement precision
If auto refractors are used for PD measurement, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent creates a simplified optical copy of the auto refractor's measurement capability using a standard camera. Instead of requiring complex automated refractoring equipment, the system captures images of the user's eyes and processes them through software algorithms that replicate the measurement function at a fraction of the cost and complexity.
Solution Approach 2:
The patent replaces the complex mechanical and optical systems of auto refractors with a simple camera-based imaging system. The measurement function is achieved through digital image processing and geometric calculations rather than complex optical mechanisms, dramatically reducing device complexity while maintaining measurement capability.
Data Source
AI summary
Accurate measurement of pupillary distance, PD, is necessary to make prescription eye glasses as well as configuring VR headsets, and using other binocular optical devices. Today, many people are ordering eyeglasses on line and obtaining their PD is often problematic for a number of reasons as the prior art fails to provide consumer friendly PD measurement systems. A disclosed eyeglass frame system comprises reference marks of known locations upon the frames. A smart phone may be used to locate the consumer's pupils, while the consumer is wearing the frames. The consumer's pupils may be marked or tagged upon a digital image of the consumer wearing the frames. By use of angles in the sight lines of the camera lens and other variable values and the known relative distances of the frame markings, a consumer's pupillary distance can be quickly and accurately derived.