Self-adaptive Constant-Current Driving Circuit for Multi-Color LED
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Solution Overview
Problem
Conventional three-channel multi-color LED driving circuits with independent constant currents result in fluctuated brightness and discontinuous color mixing due to different sums of constant currents in various color mixing conditions.
Innovation Solution
A self-adaptive constant-current driving circuit is introduced, comprising a decoder, a two-phase non-overlapping circuit, and LED constant-current driving circuits, which adjusts the constant current of each channel based on the number of lighted channels to maintain a consistent sum of currents, ensuring uniform color mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If independent constant currents are used for each channel, then each channel can be controlled independently, but the sum of constant currents fluctuates and brightness becomes unstable
Solution Approach 1:
The patent introduces a feedback mechanism where the constant current for each channel is dynamically adjusted based on the number of active channels. The control circuit detects the number of lighted channels and automatically scales the current allocation, ensuring that the total current remains stable while maintaining independent channel control capability.
Solution Approach 2:
The patent transitions from static independent constant currents to dynamic adaptive currents. The current for each channel is no longer fixed but varies based on real-time detection of active channels, allowing the system to maintain stable total current while preserving operational flexibility.
2Device complexity
If independent constant currents are used for each channel, then channel control is simplified, but color mixing becomes discontinuous
Solution Approach 1:
The control circuit incorporates feedback to detect the number of active channels and adjust current allocation accordingly. This ensures that when channels are activated in different combinations, the total current remains consistent, enabling smooth transitions and continuous color mixing without requiring complex control algorithms.
3Stability of the object's composition
If PWM duty ratio algorithms are used to adjust brightness, then continuous color mixing can be achieved, but the number of mixed colors is limited
Solution Approach 1:
The patent changes the fundamental parameter from PWM duty ratio (temporal modulation) to adaptive constant current (amplitude modulation). By dynamically adjusting the current magnitude based on the number of active channels, the system achieves continuous color mixing with a vastly expanded color gamut, theoretically enabling 256×256×256=16777216 mixed colors.
Data Source
AI summary
A self-adaptive constant-current driving circuit for a three-channel multi-color LED, including a decoder, a two-phase non-overlapping circuit, and a LED constant-current driving circuit, where the decoder determines the number of lighted channels according to a first input signal, and generates a first switch control signal and a second switch control signal; the two-phase non-overlapping circuit modulates the first switch control signal into a first two-phase non-overlapping signal and a second two-phase non-overlapping signal, and modulates the second switch control signal into a third two-phase non-overlapping signal and a fourth two-phase non-overlapping signal; the LED constant-current driving circuit controls an on/off state of the respective channel of LED according to a second input signal, and outputs a current for controlling a brightness of the respective channel of LED according to the first two-phase non-overlapping signal, the second two-phase non-overlapping signal, the third two-phase non-overlapping signal, and the fourth two-phase non-overlapping signal.