Dimmable LED Light Unit Amplitude Control
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Solution Overview
Problem
Existing dimmable light units for passenger transport vehicles, such as aircraft, create strain on the electricity network due to non-continuous current flow from pulse width modulation, leading to inefficiencies and potential back effects on the network.
Innovation Solution
A dimmable LED light unit with an LED drive and control module that adjusts both the drive current amplitude and duty cycle to achieve desired light intensity, reducing strain on the power source and eliminating switching-related issues by using drive current amplitude variation for high light intensities and duty cycle variation for low light intensities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If pulse width modulation is used to drive LEDs for dimming, then light intensity control is achieved, but non-continuous current flow creates strain on the electricity network and switching artifacts
Solution Approach 1:
The patent changes the control parameter from duty cycle modulation to current amplitude modulation. The LED drive circuit varies the amplitude of the drive current while maintaining a continuous flow, eliminating the switching artifacts and network strain associated with pulse width modulation while achieving the desired dimming effect.
Solution Approach 2:
The patent implements continuous current flow to the LEDs by eliminating the switching off periods inherent in PWM. The LED drive circuit provides a continuous analog current signal that smoothly varies in amplitude, ensuring uninterrupted light emission and eliminating the harmful switching effects on the electricity network.
2Illumination intensity
If duty cycle variation is used for dimming, then light intensity is controlled, but precision is limited at high light intensities
Solution Approach 1:
The patent transitions from controlling light intensity via duty cycle percentage to controlling via current amplitude. This parameter change enables precise control across the entire brightness range, particularly improving precision at high intensities where duty cycle approaches 100% and loses resolution.
3Illumination intensity
If non-continuous current flow is used for PWM dimming, then dimming is achieved, but circuit elements must handle switching stress
Solution Approach 1:
The patent eliminates the discontinuous switching action by providing a continuous current flow to the LEDs. This removes the need for high-speed switching circuit elements and reduces the complexity of the drive circuit, as standard analog current control components can be used instead of specialized PWM switching components.
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 reduces the load on the electricity network, improves dimming precision, and eliminates switching-related artifacts, making the dimmable LED light unit more efficient and effective while maintaining consistent light quality.
Implementation Method 1
at least one LED
Data Source
Figure 1
Figure 2~4
Figure 5a
AI summary
A dimmable LED light unit (2), in particular for a passenger transportation vehicle, such as an aircraft, a road vehicle, a ship or a rail car, is disclosed that comprises a power input (10) adapted to receive electrical power from a power source (30), at least one LED (4), and an LED drive and control module (6) coupled between the power input (10) and the at least one LED (4), wherein the LED drive and control module (6) is adapted to receive an LED control signal indicative of a desired light intensity of the dimmable LED light unit (2). The LED drive and control module (6) is configured to provide a drive current to the at least one LED resulting in the desired light intensity of the dimmable LED light unit (2), the drive current having a drive current amplitude and a drive current duty cycle, wherein the LED drive and control module (6) is configured to set the drive current amplitude within an amplitude range and to set the drive current duty cycle within a duty cycle range in response to the LED control signal.