Current Adjustment Circuit for LED Dimming Consistency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing LED light source dimming technologies, such as CCM and DCM, face challenges in consistency and control, particularly in multi-LED circuits, due to factors like bus voltage, inductive inductance, and LED voltage, leading to inconsistent dimming effects across multiple LED light sources.
Innovation Solution
A current adjustment circuit incorporating a dimming switch, zero-crossing detector, and time control sub-circuit with capacitors and current sources, which controls the switching cycle by adjusting the delay time and charging times of capacitors to regulate the average current and luminous intensity, thereby enhancing consistency across multiple LED light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If DCM dimming is used to enable easy dimming control, then dimming control is simplified, but consistency among multiple LED light sources deteriorates due to varying inductive current
Solution Approach 1:
The patent employs feedback mechanisms through zero-crossing detection of the inductive current and voltage comparison between capacitors to precisely control the switching cycle. This feedback ensures that despite variations in bus voltage, inductive inductance, and LED voltage, the dimming control maintains consistency across multiple LED light sources by dynamically adjusting the switching timing based on actual circuit conditions.
Solution Approach 2:
The patent changes the timing parameters of the switching cycle by adjusting the delay time and switching period based on the charging times of capacitors. This parameter adjustment compensates for variations in inductive current caused by different LED characteristics, thereby maintaining consistent dimming effects across multiple LED light sources while preserving the ease of DCM dimming control.
2Quantity of substance
If multiple LED light sources are connected in a circuit, then lighting coverage is improved, but dimming consistency deteriorates due to poor LED consistency and large differences in dimming effects
Solution Approach 1:
The feedback mechanism monitors the actual current and voltage conditions in the circuit and adjusts the switching cycle accordingly. This ensures that each LED light source, regardless of its individual characteristics, receives appropriate current control, thereby maintaining dimming consistency across multiple LED light sources while allowing increased lighting coverage.
Solution Approach 2:
By dynamically adjusting the switching cycle parameters based on real-time circuit conditions, the system compensates for variations among multiple LED light sources. This parameter adaptation ensures uniform dimming effects across all LED light sources in the circuit, enabling scalable lighting solutions without sacrificing consistency.
3Stability of the object's composition
If CCM dimming is used to maintain continuous current, then lighting stability is improved, but control difficulty increases and inductor saturation occurs
Solution Approach 1:
The patent employs periodic switching action with controlled duty cycles to achieve both lighting stability and ease of control. By periodically resetting the inductor current to zero and then controlling the on-time based on capacitor charging, the system maintains stable lighting output while avoiding the control difficulties and saturation issues associated with continuous conduction mode.
Solution Approach 2:
The patent performs preliminary action by pre-charging capacitors to specific voltages before initiating the switching cycle. This preliminary preparation establishes precise timing references that simplify control while ensuring stable lighting output, avoiding the need for complex continuous current regulation required in CCM dimming.
Data Source
AI summary
The present disclosure provides a current adjustment circuit. The current adjustment circuit may include a dimming switch coupled to an inductor disposed in a lighting sub-circuit, a zero-crossing detector, and a time control sub-circuit. The dimming switch may be configured to control power supply states of the inductor. The zero-crossing detector may be configured to detect an ending time of a current of the inductor, and to generate a zero-crossing signal. The time control sub-circuit may include a first capacitor and a second capacitor and configured to receive the zero-crossing signal, and generate a control signal that is configured to control the dimming switch to initiate a switching cycle for the inductor. The switching cycle may start after a delay time and the delay time is controlled by a first charging time of the first capacitor and a second charging time of the second capacitor.