Pixelated Display Non-Uniformity Calibration via Adaptive Transfer Functions

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Solution Overview

Problem

Pixelated displays, such as light projectors using IRLEDs, exhibit non-linear and non-uniform intensity output relationships with driving current, which are sensitive to temperature and manufacturing anomalies, leading to inaccuracies in projected images, particularly in applications requiring precise light intensity control.

Innovation Solution

A calibration system and method that involves an imager and a non-uniformity determination processor to repeatedly select and illuminate subsets of pixels with varying driving currents, capture and store intensity values, and update driving currents based on determined intensity values, creating an adaptive transfer function for each pixel to ensure accurate light projection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the same driving current is applied to all pixels, then the operation is simple, but the output light intensity is non-uniform across pixels

Engineering Contradiction:

Improvesimplicity of driving current applicationVSAvoiduniformity of light output

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent applies local quality by assigning individualized transfer functions to each pixel based on its measured characteristics. Each pixel receives a customized driving current calculation using its specific transfer function, ensuring uniform light output across all pixels despite manufacturing variations in the LED array.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If iterative calibration is performed for all pixels, then the uniformity of light output is improved, but the time and complexity of the calibration process increases

Engineering Contradiction:

Improveuniformity of light outputVSAvoidcalibration time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent segments the calibration process into two phases: an iterative calibration phase performed during manufacturing to establish transfer functions for each pixel, and a rapid execution phase during operation where pre-determined transfer functions are applied. This segmentation reduces the time penalty by performing detailed calibration once during manufacturing rather than repeatedly during operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary action by completing the iterative calibration process during manufacturing before the projector enters service. The transfer functions are pre-determined and stored, allowing rapid execution during operation without requiring repeated time-consuming iterative calibration.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If temperature effects are not compensated, then the system is simpler, but the accuracy of light intensity control deteriorates due to heat sensitivity

Engineering Contradiction:

Improvesimplicity of systemVSAvoidaccuracy of light intensity control

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent addresses temperature effects by incorporating temperature-dependent parameters into the transfer functions. The calibration process measures pixel characteristics at different temperatures, and the resulting transfer functions compensate for thermal drift, maintaining accurate light intensity control despite temperature variations during operation.

Inventive Principle:

Principle #35Parameter changes

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 approach allows for precise determination and correction of non-uniformity in pixel output, enabling accurate projection of images and video frames by establishing a unique transfer function for each pixel, reducing errors and ensuring reliable performance in applications like missile guidance systems.

Implementation Method 1

an imager positioned to capture the image produced by the pixelated display

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 2

Pixelated displays (e.g. light projectors) drive light emitting elements such as infrared light emitting diodes (IRLEDs) to project an IR image

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS10511816B2Non-uniformity output determination for light projectors

Publication Date: 2019.12.17 UNIVERSITY OF DELAWARE

AI summary

The present invention relates to a calibration system and method including a pixelated display including pixels for projecting an image, an imager positioned to capture the image produced by the pixelated display, and a processor. The processor is configured to determine and measure non-uniformity in the image produced by the pixelated display by repeatedly selecting and illuminating a subset of the pixels in the pixelated display with respective driving currents, controlling the imager to capture the image projected by the subset pixels, determining and storing, for each pixel in the subset, an intensity value produced in response to the respective driving current, and updating, for each pixel in the subset, the respective driving currents based on the determined intensity value and previously stored intensity values corresponding with previously stored driving currents.