LED Driving Circuit Automatic Series Parallel Switching
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Solution Overview
Problem
Existing LED driving circuits face challenges in efficiently managing LED light emission with AC power supply due to nonlinear LED characteristics, leading to increased size, cost, and power consumption, as well as inefficiencies in switching timing and power loss when switching between series and parallel connections of LED blocks.
Innovation Solution
An LED driving circuit that switches current paths based on the output voltage of a full-wave rectification circuit, eliminating the need for digitally controlled switch circuits and automatically determining the optimal connection mode between series and parallel configurations to minimize power loss and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If multiple LED blocks are connected with switch circuits to extend light-emission period, then the light-emission duration is improved, but the device complexity and power consumption increase
Solution Approach 1:
The patent extracts and eliminates the switch circuit from the LED driving system. Instead of using active switching components to change connection modes, the invention uses passive diode bridge rectification with LED blocks directly connected to the rectified voltage, allowing the system to automatically adapt to voltage variations without complex switching control.
Solution Approach 2:
The LED blocks themselves determine their operating state based on the rectified voltage level. When voltage is sufficient, LEDs naturally conduct and emit light; when voltage drops below forward voltage threshold, they automatically stop conducting. This self-regulating behavior eliminates the need for external switch circuits to control connection modes.
2Duration of action of moving object
If switch circuits are used to change connection modes, then the light-emission period is extended, but the power consumption increases
Solution Approach 1:
The patent removes the power-consuming switch circuit from the system. The diode bridge rectifier passively converts AC voltage to pulsating DC voltage, and LED blocks automatically respond to voltage levels without requiring active switching components that consume power during operation.
Solution Approach 2:
LED blocks self-regulate their conduction state based on the instantaneous rectified voltage. When voltage exceeds forward voltage threshold, LEDs conduct and emit light; when voltage drops below threshold, conduction naturally stops. This eliminates power consumption associated with active switching control.
3Device complexity
If predicted switching timing is used based on n×Vf, then the control is simplified, but the lighting efficiency decreases due to voltage variations
Solution Approach 1:
The invention implements natural feedback through the diode bridge rectifier and LED forward voltage characteristics. The rectified voltage directly reflects the instantaneous power supply state, and LED blocks automatically adjust their conduction based on whether the rectified voltage exceeds their forward voltage threshold, achieving optimal efficiency without complex predictive control.
Solution Approach 2:
The system adapts to varying power supply conditions by allowing the operating parameters (connection mode, conduction state) to change naturally with the rectified voltage level. Instead of fixed predicted switching timing, the LEDs automatically adjust their state based on the actual instantaneous voltage, maintaining high efficiency across different operating conditions.
4Duration of action of moving object
If LED blocks with different impedances are connected in parallel, then the light emission is maintained, but power loss occurs due to current regulation requirements
Solution Approach 1:
The patent allows LED blocks to operate in partial conduction modes based on available voltage. When rectified voltage is sufficient, multiple LED blocks can conduct simultaneously; when voltage is limited, only blocks with lower forward voltage thresholds conduct. This partial operation eliminates the need for active current regulation, reducing power loss while maintaining continuous light emission.
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 reduces the need for multiple switch circuits, optimizes switching timing, and minimizes power loss by automatically adjusting current paths according to the output voltage and actual forward voltages of LEDs, thereby enhancing the efficiency and duration of LED light emission.
Implementation Method 1
a full-wave rectification circuit 82, a start-point circuit 20, an intermediate circuit 30, and an end-point circuit 40 which are connected in parallel between a positive power supply output 83 and a negative power supply output 84 of the full-wave rectification circuit 82
Implementation Method 2
LEDs have nonlinear characteristics such that, when the voltage being applied across the LED reaches or exceeds its forward voltage drop, a current suddenly begins to flow. Light with a desired luminous intensity is produced by flowing a prescribed forward current (If)
Data Source
AI summary
The invention is directed to the provision of an LED driving circuit that switches the connection of LED blocks with proper timing in accordance with the supply voltage and the Vf's specific to individual LEDs contained in each LED block. The LED driving circuit includes a rectifier, a first circuit which includes a first current detection unit for detecting current flowing through a first LED array, and a first current control unit for controlling current flowing from the first LED array to a negative power supply output in accordance with the current detected by the first current detection unit, and a second circuit which includes a second current detection unit for detecting current flowing through a second LED array, and a second current control unit for controlling current flowing from a positive power supply output to the second LED array in accordance with the current detected by the second current detection unit, and wherein a current path connecting the first LED array and the second LED array in parallel relative to the rectifier and a current path connecting the first LED array and the second LED array in series relative to the rectifier are formed.