This invention relates to a sealed, internal ly forced air , convect ion cooled, f lameoroof l ight source for use in hεzarαous at osoneres .

Light sources are wel l known and widely used in many types of endoscopic and other inspect ions. The majority of these units force air from the surrounding atmosphere over the I amo envelope for cool ing, and are therefore considered undesireabla for use in haza dous atmospheres. Those units w ich are classified for use in hazardous areas use one or more of the fol lowing msthoαs of cool ing; exot ic gases, a high pressure compressed air suβply or a mass of material to both absorb and dissipate the lamp's heat.

The l ight source described herein could if required use a gas other than forced air cool ino.

Because the l mp generates a considerable amount of heat , i t reαuire≤ a large amount of cool ing when used in hazardous areas; the current designs of l ight sources are either exoensive to maintain or diff icult to use or have a relat ively short duty cycle before overheating and being thermal ly tripped.

According to this present inven ion this internal ly forced ai r convection cooled light source is a sealed box l ike structure which has cool ing fins on both sides of the four normal ly vert ical primary wal ls. Air contained within the sealed compartment of the l ight source is circulated by a fan over the lamp and optical system io cool them. This air is also circulated through internal ly finned ducts. The f ins in these ducts absorb heat from the forced air. Heat from the internal fins is transmitted by conduction to the external fins which in turn give up their heai to the ambient atmosphere. Li nt from the lamp is passed througn a sealed optical window in one w l l to a multi function fully vairable mounting for a fibre optic l i t guiαe or another l ight transmitting medium.

The specific embodiment of the invent ion wi l l now be describee by example, with reference to the accompanying drawing in hicn:-

Fioure 1 shows the external conf iαurat i on of the l ight source

igure 2 shows the principle of the internal forced air cool ing s stern.

Referring to Figure 1 the forced air convection cooled l ight source comprises of a case 10 with a l id, 11 w ich when fitteα prevents he interchange of gases, between case internal cavity and ambient atmosphere. The external vertical finned primary wal ls 12 are

protected by rod frame 13 w ich orof ruoes front and back to iorrr. carrying handles for the ooerator. At tne front of the i .' nt source is a Multi Function Ful l Variable Mount 14 which has an orit ice . 1 for ootical l ight guides. Electrical oower for the l ight source s provided by and through a sealed cable l i .

Figure 2 shows the internal configuration of the l ight source with the lid 11 removed. The l ight from the lamp 17 is focussed througn the optical system 19 onto the ootical wi dow 1? wnich is positioned behind the Mu 1 t i Function Ful ly Variable Mount 14. The fan unit 20 is posit ioned behind the lamp 17 and in front of the electronic power supply system 21. The primary wal ls 12 ere al l finned vertical ly on the outside and horizontal ly on the inside. The inside horizontal fins of the primary walls form part of a uct system 22. Partitions 23 form the inner most wal l of these ducts. The part itions 22 are left open on two of the wal ls to provide an inlet and out let for air from the fan 20. The air which is contained within the seaied enclosure is circulated by the fan 2D over the i amp 1? and opiicai system 18. After passing over the lamp 17 and ootical system lδ the, now heated, air enters the inlet orifice of the finned ducts 22. W i lst passing through these finned ducts the air gives up a proportion of its heat. The now cooler air exits the ducts into the electronics compartment 21, in which is situated the inlet of the fan