Control of the luminous intensity of power LEDs by using the photoelectric effect characteristics of said power LEDs
First Claim
1. Method for operating a signal lamp, in particular a railway signal lamp,wherein the signal lamp comprises as its illuminant at least one light emitting diode (=LED),and wherein the luminous intensity of the signal lamp is adapted to the brightness of the surrounding,whereinat least one LED is operated during first time intervals as the illuminant of the signal lamp,and during second time intervals, the at least one LED is operated as a photo diode,that first and second time intervals alternate over time, in particular periodically,and that the output voltage of the LED during the second time intervals is used to control the operating current of the at least one LED during first time intervals.
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Abstract
A method for operating a signal lamp (1), in particular a railway signal lamp, wherein the signal lamp (1) comprises as its illuminant at least one light emitting diode (=LED) (2), and wherein the luminous intensity of the signal lamp (1) is adapted to the brightness of the surrounding, is characterized in that the at least one LED (2) is operated during first time intervals as the illuminant of the signal lamp (1), and during second time intervals, the at least one LED (2) is operated as a photo diode, that first and second time intervals alternate over time, in particular periodically, and that the output voltage of the LED (2) during the second time intervals is used to control the operating current of the at least one LED (2) during first time intervals. The inventive method does without a separate sensor, thus allowing the use of a corresponding signal lamp arrangement which is simple and inexpensive.
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Citations
10 Claims
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1. Method for operating a signal lamp, in particular a railway signal lamp,
wherein the signal lamp comprises as its illuminant at least one light emitting diode (=LED), and wherein the luminous intensity of the signal lamp is adapted to the brightness of the surrounding, wherein at least one LED is operated during first time intervals as the illuminant of the signal lamp, and during second time intervals, the at least one LED is operated as a photo diode, that first and second time intervals alternate over time, in particular periodically, and that the output voltage of the LED during the second time intervals is used to control the operating current of the at least one LED during first time intervals.
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4. Signal lamp arrangement, in particular railway signal lamp arrangement, with a signal lamp comprising at least one light emitting diode (=LED) as its illuminant,
and with an electronic circuit for operating the signal lamp, wherein that the electronic circuit comprises a supply means for supplying the at least one LED with operating current, a tapping means for tapping the LED voltage of the at least one LED, a comparison means for comparing the LED voltage to a reference voltage, wherein the comparison means is connected to the supply means for controlling the supply means, and a switching means for switching the electronic circuit from a first state into a second state and vice versa, wherein in the first state, the supply means is connected to the at least one LED, and the comparison means is disconnected form the at least one LED, in particular wherein the tapping means is disconnected from the comparison means, and wherein in the second state, the supply means is disconnected from the at least one LED, and the comparison means is connected to the at least one LED, in particular wherein the tapping means is connected to the comparison means.
Specification