LED Lamp Brightness Control via Voltage Feedback
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Solution Overview
Problem
Existing LED lamps in medical diagnostic devices, such as microscopes and endoscopes, face challenges in dimming due to their higher resistance compared to incandescent lamps, making it difficult to achieve fine brightness adjustments essential for medical applications, and replacing the existing electrical supply apparatuses with rheostats is economically and logistically impractical.
Innovation Solution
A control unit that adjusts the LED current by acquiring a parameter indicating the changing supply voltage and providing a control voltage to simulate the brightness-voltage characteristic curve of incandescent lamps, allowing for continuous dimming within a predefined voltage range, using an electrical load resistor to simulate the incandescent lamp's resistance and an adjustable series resistor to regulate the supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If LED lamps replace incandescent lamps in medical diagnostic devices, then energy consumption is reduced and service life is extended, but brightness control becomes difficult due to higher LED resistance
Solution Approach 1:
The patent introduces a control unit as an intermediary device between the voltage source and the LED lamp. This control unit includes an acquisition apparatus that measures the supply voltage and a provision apparatus that generates an appropriate control signal based on the measured voltage, thereby enabling precise brightness control of the LED lamp while maintaining compatibility with existing voltage sources in medical diagnostic devices
Solution Approach 2:
The patent changes the control parameter from direct voltage control (which works for incandescent lamps) to current control through a control unit. The control unit adjusts the LED current based on the supply voltage parameter, allowing the LED brightness to be controlled in a manner similar to incandescent lamps while accounting for the LED's higher resistance and non-linear current-voltage characteristics
2Duration of action of stationary object
If LED lamps replace incandescent lamps, then service life is extended by one or more orders of magnitude, but compatibility with existing voltage sources requires extensive hardware updates
Solution Approach 1:
The control unit is designed to be universally compatible with existing voltage sources in medical diagnostic devices. It can adapt to different supply voltages and automatically adjust its operation accordingly, allowing LED lamps to replace incandescent lamps without requiring updates to the existing voltage source hardware, thereby maintaining backward compatibility while enabling the use of longer-lasting LED technology
3Reliability
If conventional LED drivers are used to control LED current, then constant current is provided, but fine brightness adjustments are lost due to LED's higher resistance
Solution Approach 1:
The control unit incorporates an acquisition apparatus that continuously monitors the supply voltage and uses this feedback information to adjust the control signal provided to the LED driver. This feedback mechanism enables the system to maintain constant current protection while simultaneously achieving fine brightness adjustments by dynamically adapting the control signal based on the actual supply voltage conditions
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
Enables precise brightness control of LED lamps, matching the dimming characteristics of incandescent lamps, while maintaining compatibility with existing voltage sources, thus allowing for seamless replacement of incandescent lamps without the need for extensive hardware updates in medical devices.
Implementation Method 1
Light-emitting diodes, or LEDs in short, are gradually taking over all areas of everyday life
Implementation Method 2
acquiring a parameter which indicates the changing supply voltage of the supply apparatus
Data Source
AI summary
A method is described for adjusting the brightness of at least one LED according to a changing supply voltage provided to the at least one LED includes acquiring a parameter which indicates the changing supply voltage; and providing, on the basis of the acquired parameter, a control voltage of the at least one LED for adjusting an LED current such that the at least one LED has a predefined relative brightness change over the predefined voltage range. A control unit and an LED lamp which implement the method described here are also discloses. Furthermore, an LED lighting apparatus and a medical diagnostic device having the LED lamp disclosed here are described.