Light for the interior of an aircraft

BACKGROUND

Field of the invention

The present invention relates to a light for the interior of an aircraft and, in particular, to a wash light for an aircraft,

Related prior art

For illuminating the interior of an aircraft, it is known to use diverse lights. One type of light is also called "wash light" and comprises light sources the light rays of which are directed along the inner surfaces of the sidewalls and ceiling of the aircraft cabin.

It is an object of the present Invention to provide a light for the interior of aircraft which is LED-based and comprises a homogeneous Sight color.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a fight for the interior of an aircraft, in particular a wash light for an aircraft, comprising :

- a first group of white LEDs each having an InGaN semiconductor material chip, and

a second group of amber colored LEDs each having an InGaN

semiconductor material chip. According to the invention, it is proposed to use at least two different types of LEDs namely a first group of LEDs comprising white LEDs and a second group of LEDs comprising amber colored LEDs, All the LEDs used in the light according to the invention are based on the same semiconductor material technology and comprise InGaN semiconductor material chips.

With the new combination of LEDs according to the present invention a more homogenous color spectrum than current wash light systems can be achieved. In particular, using the same semiconductor material for the LED chips, all the LEDs used are subjected to the same or at least similar aging effects so that the color spectrum maintains substantially homogenously over the life time of the light.

In one aspect of the invention, the light further comprises a third group of red colored LEDs each having an InGaN semiconductor material chip.

In another embodiment of the present invention, the light comprises a fourth group of blue colored LEDs each having an InGaN semiconductor material chip, Basically, the light according to the invention may comprise a housing within which the different colored LEDs are arranged, the housing comprising a light exit opening, and a lens arranged in the light exit opening.

According to another aspect of the present invention, the different colored LEDs define color spaces in the CIE 1931 chromaticity diagram as follows:

and, if applicable

and, if applicable

Due to leak of amber and red wave length in the emission spectrum of white LEDs in the past, it was necessary to add LEDs with the missing wave length to the wash lights to obtain a homogeneous light color.

With the availability of white LEDs and amber LEDs in InGaN technology that are emitting a wide spectrum from amber into red, red colored LED are no longer necessary anymore and the mainly used color option such as coid white, warm white, amber and blue with just 3 control channels can be offered therewith.

Due to the use of the same technology for the LEDs (InGaN), similar aging performance of the 3 LED colors can be expected.

Due to the added complexity of the control system and the distance of the white emitters it is important to minimize the number of different LEDs to fill up the light spectrum to receive a good Color Rendering Index (CRI) .

Due to the installation a main light distribution of 60° is required. To achieve the required light distribution, an additional lens is used to the light distribution angle of the LEDs themselves.

For a homogeneous color distribution it is suitable to keep the LED chip within one line under the lens.

Due to this, it is suitable to keep the distance between the white emitter as small as possible, otherwise spots will be visible on the side wall or ceiling panel.

The main innovation Is related to the 3 channel wash light that provides a very good CRJ for white light together with the possibility to change the light color continuously to dark amber and blue. And therewith the light is able to provide the mostly used multi color interior light that are currently used.

A further advantage of the new system is also that onfy LEDs are used that are based on InGaN chip technology. Therefore the aging process of the different LED colours will be equivalent.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in more detail referring to an

embodiment of the present invention as well as to the drawing in which

Fig. 1 shows a representation of the CIE 1931 chromaticity diagram mentioning preferred chromaticity areas for the white, amber, red, and blue LEDs which according to one preferred

embodiment of the invention can be used (with red and blue applicable in combination or alone in addition to the white and red LEDs), Fig, 2 a front view of a design of a wash light comprising one single row of adjacent LEDs in InGaN technology and different colors white, amber, and blue (in this arrangement), and Fig. 3 a cross-sectional view taken along line III-III of Fig. 2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Figs. 2 and 3 show views of a wash light 10 to be used for illuminating the side walls and/or ceiling of an aircraft cabin. The wash light 10 comprises a housing 12 defining a light exit opening 14 and a lens 16 arranged in the light exit opening 14. The lens 16 is made from synthetic materials of different optical density like e.g. granular polycarbonate having a relatively high transmission factor and optically defuse properties.

Behind the lens 16 within the housing 12 there is positioned an arrangement of different LEDs in InGaN technology. The LEDs comprise a plurality of white LEDs 18, amber colored LEDs 20 and in this embodiment additional blue colored LEDs 22. Instead of the blue colored LEDs, the wash light 10 also may comprise red colored LEDs, Also it is possible that beside the white and amber colored LEDs 18, 20, both blue and red colored LEDs can be provided. All the LEDs 18, 20, 22 are arranged on a substrate plate 24 or PCB arranged within the housing 12. In the present embodiment according to Figs. 2 and 3, the different colored LEDs are arranged in the repeated order "white, amber, blue".

The different colored light of the individual LEDs 18, 20, 22 is transmitted by the LEDs 18, 20, 22 and is mixed already in part within the housing 12 and, in any event, through the lens 16 so that the homogeneously colored and mixed overall light of the different colored LEDs is transmitted by the wash light 10. It is to be noted here that providing a lens in the wash light 10 according to the embodiment is not necessary. Depending on the distance to the LEDs 18, 20, 22, their light rays are homogeneously mixed automatically without the aid of the lens 16. A lens as a cover for the housing 12 is advantageous with regard to the feature that by way of the lens the light exiting the housing 12 can be directed as suitable in the specific application.

In the diagram according to Fig. 1 preferred color spaces (color areas) for the white, amber, blue and red LEDs are mentioned.

Although the invention has been described and illustrated with reference to specific embodiments thereof, it is not intended that the invention be limited to those illustrative embodiments. Those skilled in the art will recognize that variations and modifications can be made without departing from the true scope of the invention as defined by the claims that follow. It is therefore intended to include within the invention all such variations and modifications as fall within the scope of the appendant claims and equivalence thereof.