Flash LED Calibration via Photo Detector Array
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Solution Overview
Problem
Traditional methods for calibrating flash LEDs in mobile devices are labor-intensive and inefficient, particularly for LED flashes, due to their low intensity and temporal and spatial non-uniformities, making it difficult to achieve satisfactory image quality in dark environments.
Innovation Solution
A portable calibration system using a photo detector panel with an array of light sensing elements, aligned with the camera's field of view, samples the flash LED's output at high frequency to determine spatial and temporal variations in brightness and chromaticity, allowing for precise measurement and correction of light output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional film camera imaging methods are used to measure flash LED output, then brightness and uniformity can be assessed, but the process becomes labor intensive and difficult to implement due to low LED flash intensity and temporal/spatial non-uniformities
Solution Approach 1:
The patent replaces the mechanical film camera imaging system with an electronic photo detector array system. The photo detector panel electronically captures brightness and chromaticity data at multiple locations and time points during the flash LED operation, eliminating the need for manual film development and analysis while providing more precise and efficient measurements of the LED's temporal and spatial non-uniformities
Solution Approach 2:
The patent creates an electronic copy of the flash LED's light output pattern by using the photo detector array to capture brightness and chromaticity information at multiple locations and times. This electronic copy can be processed automatically to assess uniformity and brightness characteristics, replacing the physical film copy method and enabling more efficient calibration
2Measurement precision
If high-speed photo detector array is used to capture flash LED output, then temporal and spatial variations can be measured precisely, but the system complexity and cost increase
Solution Approach 1:
The patent divides the measurement task into multiple independent photo detector elements arranged in an array, with each detector capturing light at a specific location and time point. This segmentation allows the system to measure spatial and temporal variations by combining data from multiple simple detectors rather than requiring a single complex measurement system
Solution Approach 2:
The photo detector panel serves multiple functions simultaneously: it measures brightness, chromaticity, spatial uniformity, and temporal characteristics all in one system. The same array of photo detectors captures multiple types of data during the flash LED operation, reducing the need for separate specialized measurement devices
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 provides a cost-effective, quantitative assessment of flash LED uniformity and chromaticity, enabling improved image quality in mobile devices by accurately measuring and adjusting the light output, which is essential for consistent and bright illumination across the camera's field of view.
Implementation Method 1
a portable calibration system using a photo detector panel with an array of light sensing elements
Data Source
AI summary
Techniques for calibrating spatial uniformity of light emitted by a light source include receiving light from a unit under test with an array of photo detectors. Sampling circuitry receives an output signal generated by each of the photo detectors in response to the received light, and samples each of the output signals to generate a sampled output signal for each of the photo detectors. One or more processors determine a spatial uniformity measure of one or both of luminous intensity and chromaticity for the received light using the sampled output signals.