LED Control Device Rising Current Profile for Flux Stability
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Solution Overview
Problem
Radiation-emitting semiconductor components, such as LEDs, experience a decrease in radiation flux during pulsed operation due to heating, leading to fluctuations in the radiation flux, which is undesirable for applications requiring uniformity and stability.
Innovation Solution
A control method and device that generates a pulsed electric operating current with a rising profile during the pulse duration, using a compensation current superimposed on the switching current, to maintain a constant radiation flux within a predetermined tolerance band, without rising or falling edges, thereby counteracting the heating-induced flux decrease.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a constant electric operating current is used during pulse duration, then the operation is simple, but the radiation flux decreases due to heating
Solution Approach 1:
The patent applies the dynamics principle by transitioning from a static constant current to a dynamic time-dependent current profile. The operating current I(t) is modulated according to a predetermined function that compensates for heating effects during the pulse duration, thereby maintaining stable radiation flux while accounting for thermal variations in the semiconductor component.
Solution Approach 2:
The patent implements parameter changes by varying the electric operating current as a function of time during the pulse duration. The current parameter is dynamically adjusted according to a predetermined temporal profile (e.g., exponential decay or linear decrease) to counteract the heating-induced reduction in radiation flux, thus maintaining constant optical output despite temperature changes.
2Stability of the object's composition
If the radiation flux is maintained constant during pulse duration, then the uniformity is improved, but the device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the optimal current profile function that compensates for heating effects. This predetermined temporal profile is established before operation based on thermal modeling and experimental characterization, allowing the control device to maintain constant radiation flux without requiring real-time temperature measurement or complex adaptive algorithms.
Solution Approach 2:
The patent introduces a current modulation function as an intermediary between the simple switching signal and the semiconductor component. This intermediate layer translates the binary switch-on/switch-off command into a sophisticated time-dependent current profile that compensates for thermal effects, thereby achieving uniform radiation flux without directly controlling temperature.
3Stability of the object's composition
If a rising compensation current is superimposed on switching current, then the radiation flux stability is improved, but the current generation complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the operating current into two independent components: a rectangular switching current that provides the basic pulsed operation, and a rising compensation current that counteracts heating effects. These two current components are generated separately and then superimposed, allowing each to be optimized independently while achieving the overall goal of stable radiation flux.
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
Ensures reliable and uniform pulsed operation of radiation-emitting semiconductor components by maintaining a stable radiation flux, suitable for applications requiring high uniformity and minimal fluctuation, and allows for independent generation of switching and compensation currents.
Implementation Method 1
Radiation-emitting semiconductor components are used, for example, as light-emitting diodes, or for short: LED
Implementation Method 2
the at least one radiation-emitting semiconductor component heats up during the pulse duration
Data Source
AI summary
A pulsed electric operating current that rises during a pulse duration is generated for operating at least one radiation-emitting semiconductor component. For this purpose, in a method for producing a control device for operating the at least one radiation-emitting semiconductor component, a temporal profile of a thermal impedance representative of the at least one radiation-emitting semiconductor component is determined. A profile of the electric operating current that is to be set is determined depending on the determined temporal profile of the thermal impedance. The control device is furthermore designed such that the profile of the operating current that is to be set is set in each case during the pulse duration.