GB2075654A - A halogen lamp par spotlight with high axial light strength - Google Patents

Abstract

A spotlight with high axial light strength, particularly for beacon- type appliances for air and ship traffic, has a light source 1 which is surrounded by a parabolic reflector 10, and is characterised in that an almost punctiform halogen-metal vapour lamp (2) mounted in the focal point (F) of the parabolic reflector (10) is provided as the light source (1). <IMAGE>

Description

SPECIFICATION A spotlight with high axial light strength The invention relates to a spotlight with high axial light strength, particularly for beacontype appliances for air and ship traffic, which has a light source which is surrounded by a parabolic reflector.

Such spotlights are known, and are used mainly for air and ship traffic as rotating or leading beacons, or as illuminating spotlights and searchlights. It is important in such appliances that a high nominal range can be achieved at the operating light strengths of such spotlights, in order, for example, to make the beacon of a lighthouse visible to a ship or a plane from considerable distances away, and therefore to allow good navigation.

In known designs, such spotlights are fitted with halogen incandescent lamps, halogenmetal vapour lamps in strip-light form, or Xenon high pressure lamps. Of these, spotlights which are equipped with halogen incandescent lamps exhibit the disadvantage that they possess a relatively low light output and are therefore uneconomical. Xenon high pressure lamps have the disadvantage that fixing and adjusting such lamps, and igniting them, is not without problems, and for this reason halogen-metal vapour lamps in strip-light form are given preference in known designs, since spotlights equipped with these lamps can attain the necessary high nominal ranges, especially at night.If the high nominal ranges are also to be attained with these spotlights by day as well, then in beacon-type appliances, for example, several spotlight elements equipped with such light sources have to be arrangement so that the beams of light produced by the separate light sources are deflected in one direction in order thereby to achieve the desired nominal ranges. Besides the high material and financial outlay for such applicances there is the disadvantage that, if such spotlights are to be used by day as searchlights over great distances, the manipulation of a plurality of spotlight elements is cumbersome and impractical.

The problem on which the invention is based is that af designing a spotlight with high axial light strength in such a way that high nominal ranges can be achieved with it by day as well.

The invention consists in providing as the light source an almost punctiform halogenmetal vapour lamp mounted in the focal point of a parabolic reflector.

This enables the partial beam of light originating from the light source and reflected by the parabolic reflector to be deflected by the latter parallel to its optical axis with low divergency, whereby the very high axial light strength desired is obtained. Since the light source is seated punctiform in the focal point, a very good beaming is made possible.

In addition, when the lamp is inserted it is not necessary to take into consideration the position of the discharge chamber relative to the reflector, since the discharge chamber is made substantially spherically symmetrical and the light source is therefore always held by a suitable lamp fixing in the vicinity of the focal point of the reflector. It is advantageous if the lamp is equipped with a two-pin plug, since this enables rapid and trouble-free changing of the lamp to be effected. Furthermore, it is advantageous if the mounting can be set, since a lamp mounting which has once been adjusted in the reflector does not then require to be readjusted even after the lamp has been changed.

it is a further advantage that the parabolic reflector is produced in highly polished anodised high-purity aluminium. In this case, a high level of reflection of the light beam produced by the light source can be obtained, which again means a high axial light strength, since the reflector reflects the partial light beam beamed into it parallel to its optical axis.

A spotlight constructed according to the invention, with which axial light strengths of up to a factor of 10 more than in conventional spotlights can be achieved, also has the advantage that by attaching appropriate colour filters individual spectral ranges of visible light with great axial light strength can be filtered out, thus enabling spotlights to be produced for coloured light which can reach great distances.

Advantages and other features of a spotlight constructed according to the invention can be found in the Drawings.

Figure 1 shows the construction of a spotlight element according to the invention.

Figure 2 is a diagram of the horizontal light strength distribution of the spotlight element shown in Fig. 1.

Fig. 1 shows a spotlight element in which an adjustable mounting 5 is fitted in the apex S of a parabolic reflector 10 which bears a light source 1 via the supporting part 4 and the lamp mounting 3. The parabolic reflector 10 can be equipped with a glass covering which prevents dirt or dust particles settling on the surface of the reflector which is produced from highly polished anodised highpurity aluminium, since this can affect the reflection properties of such sensitive surfaces very detrimentally. The parabolic reflector 10 has an aperture diameter of 360 mm and its focal length amounts to f = 60 mm.The light source 1 which in the case shown is part of a halogen-metal vapour lamp 2 (400 W compact source iodide lamp) is held via an adjustable mounting 5 which bears the lamp mounting 3 of the lamp 2 with its discharge chamber in the vicinity of the focal point (F) of the parabolic reflector 1 0. The mounting 5 is equipped with two threaded pins 7 and 6 which make possible adjustment of the seating of the lamp 2 by means of a knurled nut 8 which is locked by means of edged nuts.

Once the light source has been set, when the lamp 1 is changed it need only be removed from the mounting 3 and a new lamp plugged in, without the necessity for readjustment, if the lamp has the same dimensions. It is possible with this arrangement to beam a large part of the beam of light originating from the light source along the axis l-l, so that high axial light strengths can be attained thereby, as can also be seen in Fig. 2.

The horizontal light strength distribution of the spotlight shown in Fig. 1 is shown in Fig.

2. The light strength is shown here in relation to the angle formed with the optical axis l-l.

It can be seen that a maximum axial light strength (0 degrees) for white light of approximately 4.5 x 106 cd and for yellow light of aproximately 2 x 1 06 cd can be produced with a half-power angle of approximately 3, and a tenth-normal scattering angle of approximately 6g. Due to the small divergency of the light beam it is therefore possible to illuminate objects over great distances or to recognise it as a signal light from a great distance. With this design of spot-light element the operating light strengths as under are obtained: 16 = 0.75 x Imax for fixed light with the following nominal range widths: By day: for white light 8.6 sm for yellow light 7.1 sm By night: for white light 29 sm for yellow light 26.8 sm Such a spotlight element can therefore be fitted out as a single sealed spotlight, which achieves on its own light strengths which until now were only possible with several spotlight elements assembled together. Naturally, this unit can also be used as an element for building up spotlight fields which can then attain a particularly high level of light strength.

Claims (6)

1. A spotlight with high axial light strength, particularly for beacon-type appliances for air and ship traffic, with a light source which is surrounded by a parabolic reflector, characterised in that an almost punctiform halogen-metal vapour lamp (2) mounted in the focal point (F) of the parabolic reflector (10) is provided as the light source (1).

2. A spotlight, according to Claim 1, characterised in that the mounting (5) is disposed in the apex (s) of the reflector (10).

3. A spotlight according to Claim 2, characterised in that the mounting (5) can be adjusted.

4. A spotlight according to Claim 1 and 2, characterised in that the parabolic reflector (10) is produced from highly polished anodised high-purity aluminium.

5. A spotlight according to Claim 1 and 2, characterised in that the parabolic reflector (10) has an aperture diameter of d = 360 mm and a focal length of f = 60 mm.

6. A spotlight according to Claim 1 to 5, characterised in that the halogen-metal vapour lamp (2) is a 400W compact source iodide lamp.