LED Driver Constant Current Controller with Periodic Switching
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Solution Overview
Problem
Existing light emitting diode (LED) drivers face challenges in reducing heat generation and power consumption due to the use of bulky sensing resistors, which complicate the circuit and lead to unnecessary power consumption.
Innovation Solution
A light emitting device with a constant current controller that includes a transistor, operational amplifiers, and a switching unit connected to a sensing resistor, which periodically switches to control the current flow through the sensing resistor, allowing for constant current delivery to the LED string while minimizing heat generation and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If multiple sensing resistors connected in parallel are used to reduce heat generation, then heat generation is reduced, but the LED driver becomes more complicated and power consumption increases
Solution Approach 1:
The patent implements periodic switching of the sensing resistor connection to the transistor. The switching unit periodically connects and disconnects the sensing resistor based on a pulse signal, enabling heat reduction through intermittent operation rather than continuous parallel resistor configuration. This periodic action maintains measurement functionality while significantly reducing thermal load and circuit complexity.
2Temperature
If multiple sensing resistors connected in parallel are used to reduce heat generation, then heat generation is reduced, but power consumption increases
Solution Approach 1:
The switching unit periodically connects and disconnects the sensing resistor based on a pulse signal, enabling the system to reduce power consumption through intermittent operation. By only activating the sensing resistor when measurement is needed rather than maintaining continuous parallel resistor connections, the patent achieves significant power savings while still monitoring current effectively.
3Temperature
If a switching unit with periodic switching is used to control current flow, then heat generation and power consumption are reduced, but the control circuit becomes more complex
Solution Approach 1:
The patent combines the switching unit, pulse generator, and sensing resistor control into an integrated constant current controller circuit. By merging these functions into a single control module rather than separate components, the patent reduces overall circuit complexity while maintaining the periodic switching capability needed for heat and power management.
Solution Approach 2:
The pulse generator automatically generates the periodic switching signals without requiring external control, and the switching unit self-regulates the sensing resistor connection based on these signals. This self-service mechanism eliminates the need for additional control circuitry, reducing complexity while maintaining periodic switching functionality for heat and power reduction.
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
The solution effectively reduces heat generation and power consumption by controlling current flow through the sensing resistor, simplifying the circuit and maintaining constant current to the LED string, thereby enhancing efficiency and reducing the complexity of the LED driver.
Implementation Method 1
a transistor connected to the cathode terminal of the LED string
Implementation Method 2
controls a driving current flowing through the LED string
Implementation Method 3
a first operational amplifier including an output terminal connected to a base of the transistor
Implementation Method 4
A switching unit and a sensing resistor are connected to the transistor
Implementation Method 5
The switching unit connects and disconnects between the sensing resistor and the transistor
Data Source
AI summary
A light emitting device includes a light emitting unit and a constant current controller. The light emitting unit includes at least one LED string. The constant current controller is connected to a cathode terminal of the LED string and controls a driving current flowing through the LED string. The constant current controller includes a transistor connected to the cathode terminal of the LED string. A switching unit and a sensing resistor are connected to the transistor. The switching unit connects and disconnects between the sensing resistor and the transistor.