Light Emitting Device PWM Duty Ratio Correction for Color Shade Uniformity
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Solution Overview
Problem
Light emitting devices with multiple elements of different chromaticity can produce varying color shades when mixed, leading to design quality issues in applications like vehicle interior illumination.
Innovation Solution
A light emitting device with a receiving section for command information, a driving section for PWM control, and a storing section for correction information to adjust duty ratios based on measurement results, ensuring consistent mixed light output across multiple elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple light emitting elements with different chromaticity are used to produce mixed light, then the versatility of light color output is improved, but the uniformity of color shade across different devices deteriorates
Solution Approach 1:
The patent applies preliminary action by measuring the emission light characteristics of each light emitting element during production and storing correction information in advance. This pre-characterization allows the system to compensate for individual element variations through duty ratio corrections, ensuring color shade uniformity across different devices while maintaining the ability to output multiple light colors.
2Measurement precision
If PWM control is used to adjust brightness of individual light emitting elements, then the precision of light intensity control is improved, but the complexity of the control system increases
Solution Approach 1:
The patent implements feedback by using measured emission light characteristics to determine correction information that is stored and applied during PWM control. The system measures the actual output of each light emitting element and uses this feedback to adjust duty ratios, achieving precise light intensity control while managing control system complexity through automated correction algorithms.
Data Source
AI summary
A light emitting device, which includes a plurality of light emitting elements each having a different chromaticity of emission light, to emit mixed light produced by mixing the respective emission light of the plurality of light emitting elements together, includes a receiving section to obtain command information on the mixed light, a driving section to perform a PWM drive on the plurality of light emitting elements on the basis of the command information, and a storing section to store correction information to be set on the basis of measurement results on the respective emission light of the plurality of light emitting elements. The driving section is being configured in such a manner as to, on the basis of the correction information, correct a duty ratio in the PWM drive to be set in accordance with the command information, and perform the PWM drive on the plurality of light emitting elements.