LED Driving Circuit with Current Path Select for Power Factor
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Solution Overview
Problem
Existing LED driving devices have a low power factor due to limited current flowing through LED strings and consume significant area and power with voltage detectors.
Innovation Solution
A device comprising a power supply unit, an LED array connected in parallel, and a current path select circuit that varies current flow based on voltage levels across LED channels, eliminating the need for a voltage detector and improving power factor by increasing current driving capability as current sources are farther from the power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a voltage detector is used to detect voltage levels and control current sources, then LED channels can be turned on/off according to voltage levels, but the area and power consumption of the driving device become large
Solution Approach 1:
The patent extracts the voltage detection function from a separate voltage detector component and integrates it into the current path select circuit. The current path select circuit directly responds to voltage levels at its input terminal, eliminating the need for a dedicated voltage detector and reducing overall device area while maintaining the capability to control LED channels based on voltage levels.
Solution Approach 2:
The patent combines the voltage detection function with the current path selection function into a single current path select circuit. This circuit simultaneously performs voltage level detection and current path selection, merging multiple functions into one component to reduce area and power consumption while maintaining operational control.
2Ease of operation
If a voltage detector is used to detect voltage levels and control current sources, then LED channels can be turned on/off according to voltage levels, but the power consumption of the driving device increases
Solution Approach 1:
The patent removes the separate voltage detector component that consumes power, and instead uses the current path select circuit to directly respond to voltage levels. This extraction eliminates the power consumption associated with a dedicated voltage detection mechanism while preserving the voltage-level-dependent control capability.
Solution Approach 2:
The current path select circuit performs self-detection of voltage levels without requiring an external voltage detector. The circuit uses its own internal mechanisms to sense voltage levels and automatically selects appropriate current paths, making the system self-sufficient and reducing overall power consumption.
3Ease of manufacture
If current sources are configured with the same electrical characteristic, then the circuit design is simplified, but the power factor remains low due to limited current flowing through LED strings
Solution Approach 1:
The patent applies different electrical characteristics to different current sources based on their position in the circuit. Current sources farther from the power supply are configured with higher current capabilities, creating local variations in electrical characteristics. This improves the power factor by enabling greater current flow through LED strings connected to these distant current sources, while maintaining design feasibility through systematic differentiation.
Solution Approach 2:
The patent implements dynamic current path selection that adapts to voltage levels. The current path select circuit dynamically switches between different current sources based on the detected voltage level, allowing the system to optimize current flow and power factor in real-time rather than being constrained by fixed, uniform current source characteristics.
4Loss of energy
If inductors or capacitors are used to improve power factor, then power efficiency can be enhanced, but the device complexity and area increase
Solution Approach 1:
The patent removes traditional power factor correction components (inductors and capacitors) from the circuit design. Instead, it achieves power factor improvement through a reconfigured current path selection mechanism that directly controls current flow based on voltage levels, eliminating the need for separate reactive compensation components and reducing device complexity.
Solution Approach 2:
The patent replaces the traditional electrical mechanism of using inductors and capacitors for power factor correction with a control-based mechanism. The current path select circuit uses voltage-level-dependent switching to achieve power factor improvement, substituting passive reactive components with an active control system that is simpler and more direct.
Data Source
AI summary
The present invention introduces a device and a method for driving an LED with an improved power factor without using a voltage detector having a large amount of area and power consumption. The device for driving an LED includes a power supply unit, an LED array, and a current path select circuit. The LED array 320 is connected with the power supply unit in parallel and includes at least one LED string including LED channels LED1 to LEDn that are configured of a plurality of LEDs connected in series. The current path select circuit selects a path of current flowing from output terminals of the plurality of LED channels according to voltage levels of each of the output terminals of the plurality of LED channels.