LED Driver Dimming Control for Flicker-Free Low Intensity
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Solution Overview
Problem
Existing LED dimming technologies face challenges in maintaining color tone stability and smooth dimming at low intensities, often resulting in flicker and spottiness due to complex synchronization issues between current sources and switching units, especially when dimming down to very low levels.
Innovation Solution
An LED driver that determines setpoint intensity and color temperature, above a threshold, mixes LED groups to achieve desired output, and below the threshold, operates a single LED group at the setpoint intensity, deviating from the desired color temperature to avoid synchronization issues and reduce ripple effects, thereby ensuring stable dimming and avoiding flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If multiple LED groups are mixed to achieve desired color temperature at low intensity, then color temperature accuracy is improved, but synchronization issues cause flicker and spottiness
Solution Approach 1:
The patent extracts the problematic synchronization function by disabling LED groups instead of attempting to synchronize them at low intensities. The control device selectively disables certain LED groups when operating at low intensity levels, eliminating the synchronization requirement and thus preventing flicker and spottiness while maintaining acceptable color temperature through the remaining active groups.
2Temperature
If LED groups are mixed to achieve precise color temperature, then color tone accuracy is improved, but device complexity increases due to synchronization requirements
Solution Approach 1:
The patent removes the complex synchronization mechanism by selectively disabling LED groups at low intensities. This extraction of the synchronization function simplifies the control system while maintaining color tone accuracy through the remaining active LED groups, thereby reducing device complexity without sacrificing color performance.
3Measurement precision
If dimming is reduced to very low levels using complex synchronization, then dimming resolution is improved, but harmful effects like flicker increase
Solution Approach 1:
The patent converts the potential harm of operating multiple LED groups at low intensity (which causes flicker and spottiness) into a benefit by selectively disabling groups. This approach maintains high dimming resolution through precise control of remaining active groups while eliminating the harmful synchronization effects, thus converting a problematic scenario into a beneficial solution.
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 solution allows for stable and smooth dimming down to very low intensities (approximately 0.1%) without color shifts, improving resolution, contrast, and flexibility, while preventing spottiness and maintaining a natural color behavior similar to incandescent bulbs.
Implementation Method 1
LED driver configured to drive a plurality of LEDs, the LEDs being arranged in groups having respective different colour temperatures
Data Source
AI summary
An LED driver has outputs to drive LEDs in groups of different colour temperatures. An input is configured to receive setpoint information, and a control device is configured to determine a combined LED setpoint intensity for the groups and a combined LED setpoint colour temperature for the groups, from the LED setpoint information. If the LED setpoint intensity is above a threshold, the control device operates the LED driver outputs to mix the LED group outputs to jointly achieve the LED setpoint intensity and the LED setpoint colour temperature. If the LED setpoint intensity is below the threshold, the control device selects a single LED group, operates the LED driver output associated with the selected LED group to drive that one LED group at the LED setpoint intensity, and operates the remaining LED driver outputs to drive the remaining LED groups at zero LED intensity.