OPTICAL SMOKE DETECTION ACCORDING TO THE TWO-COLOR PRINCIPLE BY MEANS OF A LIGHT EMITTING DIODE WITH AN LED CHIP FOR LIGHT EMISSION AND WITH A LIGHT CONVERTER FOR CONVERTING PART OF THE EMITTED LIGHT INTO LIGHT OF LONGER WAVELENGTH

摘要

The invention relates to an arrangement (10) for optical smoke detection according to the two-color principle. The arrangement comprises a light emitting diode (1) and a photosensor (2) for detecting stray light or transmitted light. The light emitting diode is designed to emit light in a first wavelength range and in a second wavelength range different therefrom. According to the invention, the light emitting diode has an LED chip (3) for emitting light in the first wavelength range and a light converter (6) for converting part of the emitted light into light in the second wavelength range. The second wavelength range has a spectral full width at half maximum (BR) of a maximum of 100 nm, in particular of a maximum of 75 nm and preferably of a maximum of 50 nm. In one particular embodiment, the light converter comprises a phosphorescent luminophore having an optical decay half-life (xF) and/or optical rise half-life (xR) in the range of 10 µs to 50 ms. With the aid of a control unit (9) as part of a smoke detection unit (20) with an arrangement according to the invention, it is possible to determine the two-color ratio from the magnitude of an abrupt signal rise and/or abrupt signal fall (RS) of the detected photosensor signal directly after the switch-on/switch-off of the light emitting diode. The invention additionally relates to a smoke detector and to an optical smoke detection method.