Light Sensor Signal Compensation for Filter Variations
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Solution Overview
Problem
Current light sensors in electronic devices face accuracy issues due to variations in filter thickness and pigment or dye concentration, affecting the accuracy of lighting environment measurements.
Innovation Solution
A method is introduced to compensate for these variations by determining a compensation factor using a test light source with components outside the pass band of the color sensor, calculating the first transmission value, and applying it to correct color signals, thereby improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If color filters with pigment or dye are used in light sensors, then the light sensor can selectively sense different wavelengths, but variations in filter thickness and pigment concentration cause measurement inaccuracies
Solution Approach 1:
The patent applies preliminary action by measuring the actual transmission characteristics of each color filter using a test light source before using the filter for normal operation. The control unit determines actual transmission values for different wavelength ranges and calculates compensation factors in advance, which are then stored and applied during subsequent measurements to correct for manufacturing variations in filter thickness and pigment concentration.
Solution Approach 2:
The patent employs parameter changes by introducing compensation factors that adjust the measured light intensities based on the actual transmission characteristics of each color filter. Instead of relying on nominal transmission values, the system dynamically modifies the measurement parameters using empirically determined compensation factors derived from test measurements, thereby correcting for variations in filter properties.
2Measurement precision
If compensation factors are calculated using test light sources with components outside the pass band, then filter thickness and pigment concentration variations can be compensated, but the system complexity increases
Solution Approach 1:
The patent applies self-service by enabling the light sensor system to perform its own calibration and characterization using an integrated test light source. The control unit automatically measures the transmission characteristics of the color filters, calculates compensation factors, and stores them for use during normal operation, eliminating the need for external calibration equipment or manual adjustment procedures.
Solution Approach 2:
The patent implements universality by designing the test light source to emit light across multiple wavelength ranges, including both within and outside the pass bands of the color filters. This multi-functional approach allows a single test light source to characterize all color filters in the system, and the same compensation methodology can be applied to different filter configurations and sensor types.
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 enhances the accuracy of lighting environment measurements by accounting for filter thickness and pigment concentration variations, leading to more precise adjustments in device settings.
Implementation Method 1
The color sensor comprises an optical filter and is designed to predominantly sense light with a wavelength within a pass band of the filter
Implementation Method 2
The pigment or dye particles feature for example characteristic absorption coefficients which vary with the wavelength of light
Data Source
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AI summary
An embodiment of a method for processing light sensor signals comprises illuminating a clear sensor (CS) and a color sensor (RS, GS, BS) of a light sensor system with a test light having a test spectrum. Therein the color sensor (RS, GS, BS) comprises an optical filter and is designed to sense light with a wavelength within a pass band of the filter and the test spectrum has components outside of the pass band. A clear test signal which is generated by the clear sensor (CS) and a color test signal which is generated by the color sensor (RS, GS, BS) are received. Then a first transmission value T is determined based on the clear test signal and on the color test signal. Finally, a compensation factor Kr, Kg, Kb is calculated based on the first transmission value T and on a nominal transmission value Tn of the filter.