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Double-binned LEDs reduce inhomogeneity in rearlamps?

Brückner, Stefan and Vinh, Trinh Quang and Khanh, Tran Quoc :
Double-binned LEDs reduce inhomogeneity in rearlamps?
[Online-Edition: http://www.emk.tu-darmstadt.de/lt/forschung/publikationen/20...]
In: International Symposium on Automotive Lighting, September 2011, Darmstadt. In: International Symposium on Automotive Lighting , 9 . Darmstadt
[Conference or Workshop Item] , (2011)

Official URL: http://www.emk.tu-darmstadt.de/lt/forschung/publikationen/20...

Abstract

When developing automotive rearlamps employing multiple LEDs manufacturers face inhomogeneity problems. Realizing brake and taillight with the same LEDs introduces the need of dimming these LEDs. Widely used dimming methods are Pulse Width Modulation (PWM) and Constant Current Reduction (CCR). CCR has several advantages over PWM, including flicker-free operation and energy efficiency. On the downside, CCR can cause inhomogeneity in rearlamps, at least in combination with traditional single binned LEDs. Recently introduced double-binned LEDs are selected (binned) at two different forward currents, according to brake and taillight level. Thus, the perceived inhomogeneity could be reduced.

In our Lab we measured a number of double binned red rearlamp LEDs. For comparison reasons, we also measured single binned LEDs of the same type. We present an analysis of the results, giving answers if the spread in luminous flux or dominant wavelength changes with forward current or temperature, and if these changes lead to drop out of the ECE color range or if they are noticeable by the human eye.

Item Type: Conference or Workshop Item
Erschienen: 2011
Creators: Brückner, Stefan and Vinh, Trinh Quang and Khanh, Tran Quoc
Title: Double-binned LEDs reduce inhomogeneity in rearlamps?
Language: English
Abstract:

When developing automotive rearlamps employing multiple LEDs manufacturers face inhomogeneity problems. Realizing brake and taillight with the same LEDs introduces the need of dimming these LEDs. Widely used dimming methods are Pulse Width Modulation (PWM) and Constant Current Reduction (CCR). CCR has several advantages over PWM, including flicker-free operation and energy efficiency. On the downside, CCR can cause inhomogeneity in rearlamps, at least in combination with traditional single binned LEDs. Recently introduced double-binned LEDs are selected (binned) at two different forward currents, according to brake and taillight level. Thus, the perceived inhomogeneity could be reduced.

In our Lab we measured a number of double binned red rearlamp LEDs. For comparison reasons, we also measured single binned LEDs of the same type. We present an analysis of the results, giving answers if the spread in luminous flux or dominant wavelength changes with forward current or temperature, and if these changes lead to drop out of the ECE color range or if they are noticeable by the human eye.

Title of Book: 9th International Symposium on Automotive Lighting
Series Name: International Symposium on Automotive Lighting
Volume: 9
Place of Publication: Darmstadt
Uncontrolled Keywords: LED, rearlamps
Divisions: 18 Department of Electrical Engineering and Information Technology > Institute for Electromechanical Design > Light Technology
18 Department of Electrical Engineering and Information Technology > Institute for Electromechanical Design
18 Department of Electrical Engineering and Information Technology
Event Title: International Symposium on Automotive Lighting
Event Location: Darmstadt
Event Dates: September 2011
Date Deposited: 19 Jan 2012 13:05
Official URL: http://www.emk.tu-darmstadt.de/lt/forschung/publikationen/20...
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