Polychromatic Lighting Control via Dual PWM Segmentation
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Solution Overview
Problem
Existing lighting apparatuses struggle to precisely control the brightness and color location of polychromatic light, particularly at low brightness levels, due to limitations in duty cycle resolution and the need for high-resolution PWM generators.
Innovation Solution
The method employs modified pulse-width-modulated signals, where color-PWM signals are modulated with intensity-PWM signals to maintain duty cycle ratios, allowing for precise control of color location and brightness adjustment using a lower resolution PWM generator, with the intensity-PWM signal having a significantly shorter or longer fundamental period than the color-PWM signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-resolution PWM generators are used to control brightness at low levels, then brightness control precision is improved, but device complexity and cost increase
Solution Approach 1:
The brightness control is segmented into two independent levels: color-PWM signals control color mixing ratios while intensity-PWM signals control overall brightness. This segmentation allows each PWM generator to operate at lower resolution (e.g., 8-bit) while maintaining overall precision, avoiding the need for expensive high-resolution (e.g., 16-bit) PWM generators.
Solution Approach 2:
The control approach transitions from a single-dimensional high-resolution PWM control to a two-dimensional approach using separate color-PWM and intensity-PWM signals. By adding the intensity control dimension, the system achieves precise brightness control at low levels without requiring increased resolution in the original color control dimension, thus reducing hardware complexity.
2Illumination intensity
If duty cycles are reduced to achieve low brightness, then brightness is reduced, but color location control accuracy deteriorates due to resolution limitations
Solution Approach 1:
The control system segments brightness and color control into separate domains: intensity-PWM signals handle brightness adjustment while color-PWM signals maintain color mixing ratios. This allows brightness to be reduced without compromising color location accuracy, as each function is handled by dedicated control signals with sufficient resolution in their respective domains.
Solution Approach 2:
The intensity-PWM signal acts as an intermediary that modulates the overall brightness independently of the color-PWM signals. This intermediary control layer allows the system to adjust brightness at low levels while the color-PWM signals continue to maintain precise color mixing ratios, preventing color location control accuracy from deteriorating.
3Ease of operation
If standard PWM control is used for polychromatic light, then control is simple, but precise simultaneous control of brightness and color location is difficult
Solution Approach 1:
The control system segments the control functions into color-PWM signals for color location and intensity-PPWM signals for brightness. This segmentation maintains relative simplicity while enabling precise simultaneous control of both parameters, as each segment handles one function with dedicated resolution.
Solution Approach 2:
The system adds an intensity control dimension to the traditional color mixing control, transforming single-parameter PWM control into two-dimensional control. This dimensional expansion enables independent and precise control of both brightness and color location without significantly increasing operational complexity, as the two control dimensions can be implemented using standard PWM techniques.
Data Source
AI summary
A lighting apparatus emitting polychromatic light comprising light of at least two light-channels with different colors, wherein each light-channel is controlled by one modified pulse-width-modulated signal (modified PWM-signal), and each modified PWM-signal results from the modulation of one color-pulse-width-modulated signal (color-PWM-signal) with an intensity-pulse-width-modulated signal (intensity-PWM-signal) in order to control the brightness and color location of the polychromatic light.