DE10042275A1 - Filter coating for changing color of light reflected by long-persistence phosphorescent material has degree of spectral transmission with high transmissivity in radiated wavelength region - Google Patents

Abstract

The filter coating (2) is arranged between the eye of the observer and a long-persistence material (1) illuminated by white light. The degree of spectral transmission of the filter coating has a high transmissivity in the region of the wavelengths of the light radiation from the long-persistence material and the white light appears colored after transmission through the filter coating.

Description

1) State of the art

The invention relates to phosphorescent, long-afterglow material that is described for example in DIN 67510. This material stores the energy of the so-called excitation lighting, but only the energy of the short-wave portion, and emits it in the form of longer-wave light over a certain period of time.

When illuminated, the light is not absorbed by the long-afterglow material reflected, the incident light color is obtained essentially unchanged, so that white light turns white after reflection, possibly with a slight Color shift in particular appears in the green-yellow area.

Long-luminescent material is often used in order to keep pictograms, in particular escape signs according to DIN 4844 and according to the regulations of the German professional associations VBG 125 , recognizable for a certain time even after the light sources illuminating them have failed. However, due to the low luminance, this is associated with a clear loss of visibility and conspicuity.

Another application of long-afterglow material are guidelines in Orientation systems.

2) Criticism of the state of the art

The disadvantage of long-afterglow material is that it remains in the afterglow appears greenish to an observer, but correspondingly white when illuminated the color of the excitation lighting.

Is the luminescent material illuminated green or with a usual green film or coating covered in order to appear green when illuminated, this will be Material not sufficiently excited so that the desired afterglow effect does not  Wear comes. But even if the excitation is successful, the long-afterglow light from conventional filters are highly absorbed.

According to the state of the art, guidelines made from long-luminescent material can be used The lighting should therefore not be green. Green / white escape signs according to DIN 4844 can only glow with their white surface when illuminated, but this is much smaller than the green area, so that the above signs are noticeable when Afterglow is therefore very low.

3) Invention task

The object of the invention is to find an arrangement in which the surface of the long-luminescent material reflected or transmitted through the material white light, e.g. B. Illuminant A or Daylight appears green and in the case of Afterglow, the emitted light is weakened as little as possible by the arrangement becomes.

4) Solution of the invention task

To solve the problem of the invention it is assumed that the spectral emission long-afterglow material predominantly in the range of maximum spectral Eye sensitivity occurs in the wavelength range from 450 nm to 600 nm, in particular between 500 nm and 550 nm.

According to the invention, the long-afterglow material is made of a transparent, preferably clear transparent filter covered in the area of the maximum spectral eye sensitivity has a high permeability. Typical values are spectral transmittance from 50% to 80%, based on the afterglow of the long-afterglow material emitted light.  

Furthermore, the course of the spectral transmittance of the Filters designed so that when colored with white light, depending on the color Execution z. B. appears green or blue.

The typical structure of the arrangement can be seen in Figure 1.

The long-afterglow material 1 is covered by a filter layer 2 according to the invention. This filter layer can be optically separated or applied optically directly. Illumination 3 with white light strikes filter layer 2 and is changed spectrally during transmission before the light bundle 4 is largely diffusely reflected on the long-afterglow material 1 . The reflected light bundle 5 passes through the filter layer 2 again and enters the outside space as green light 6 .

Figure 2 shows typical spectral transmittance of filters according to the invention.

In area 7 of the light emission of the long-afterglow material, the filters have the highest possible permeability. This area 7 , together with the drop in permeability in areas 8 and 11 and the subsequent increase in area 9, determines the color location of a green filter after irradiation with white light.

A blue filter according to the invention is characterized by a high permeability in the shortwave range, the drop in transmission between 450 nm and 550 nm of the conveyed blue color impression, must be designed as low as possible to be as possible to have high degrees of transmission for the long-afterglow light.

If it is desired to excite the phosphorescent material using a filter according to the invention, the filter according to the invention must be particularly permeable in the range from 380 nm to 480 nm, since the excitation of the phosphorescent material is greatest here. This is automatically the case with blue filters. Green filters can be optimized according to the invention in such a way that the region 11 in which the transmission of the filter is reduced is kept as narrow as the generation of the green color impression allows. The proportion of light energy that can be used for excitation is thus increased and the long-afterglow material can be excited with the light of the surroundings.

A further, very elegant possibility of excitation according to the invention is to excite the long-afterglow material by separate light sources, the light of which is mainly directed at the long-afterglow material and the radiation of which does not have to pass through the filter during the excitation illumination. This is shown in Figure 3.

Figure 3 shows a section of a route guide. Here, a transparent, in this example rectangular, light guide 8 is used, in which measures 9 are taken to deflect the light 3 fed in at the ends 12 , or in which the long-afterglow material layer 1 is completely or over a large number of bridges are optically connected to it. The incident light 3 excites the afterglow effect. If the excitation lighting fails, the light radiation of the long-afterglow material 1 can be recognized as a light bundle 10 through the filter layer 2 located in front of the light guide 8 .

External light 11, which falls on the guideline from the outside, is directed after transmission through the filter layer 2 through the light guide 8 onto the long-afterglow layer, is reflected there and, after retransmission through the green filter layer, finally returns as green light in the light bundle 10 in the outside space.

This has resulted in a guideline that glows green when the excitation lighting is on and at Failure of the excitation lighting due to the long-afterglow light radiation becomes recognizable.

It is also used to indicate the direction of escape in the area of security guidelines Use of the filter according to the invention advantageous because now at Excitation lighting surfaces appearing green even in the event of afterglow can glow greenish. In these cases, it is particularly advantageous instead of a green one white contrast to choose a greenish / black contrast.

Figure 4 shows an arrow 13 with a green background area 14 . According to the invention, the green background area 14 can be long-luminescent. This also has the advantage that the larger part of the image is long-afterglow, so the sign is more striking than if the arrow and not the background area is long-afterglow. The arrow itself can advantageously be black in the case of excitation lighting.

Claims (7)

1. Between the eye of an observer and a long-afterglow material illuminated by a white light type arranged filter layer, characterized in that the spectral transmittance of the filter layer in the region of the wavelengths of light emission of the long-afterglow material has a high transmission and that white light after Transmission through the filter layer appears colored. 2. Filter layer according to claim 1 characterized in that the filter layer converts white light into green light during transmission. 3. Filter layer according to claim 1 and 2 characterized in that the filter layer in the range of wavelengths between 500 nm and 550 nm has a spectral transmittance τ <20% and white light Transmission through the filter layer is converted into green light. 4. Filter layer according to claim 1 characterized in that the filter layer converts white light into blue light during transmission.   5. Filter layer according to claim 1 and 4 characterized in that the filter layer in the range of wavelengths between 450 nm and 500 nm has a spectral transmittance τ <20% and white light the transmission through the filter layer is converted into blue light. 6. Filter layer according to claim 1 to 5 characterized in that the filter layer is designed in such a way that it is effective for excitation Wavelengths of an illumination make the filter layer as spectral as possible Has transmittance. 7. Filter layer according to claim 1 to 6 characterized in that the filter layer is designed in such a way that it is effective for excitation Wavelengths between 380 nm and 480 nm the filter layer has a transmittance τ < Has 20%, except in the wavelength ranges in which a reduction in the Transmittance is necessary, especially in the range between 400 nm and 450 nm a conversion of white light when transmitted through the filter layer into green light sure.