[0001] his iave«ik>n relates to projectors,

[0002] The aivesttioB is concerned with a projector which em ts a high powered highly concentrated beam that extends over a significant distance of say 1000 to 2000 metres or more, (Such a projector is sometimes also referred to as "a search light ^* or a "torch"). The projector has particular applicability for military aad security purposes and is referred to herein as "a .military projector",

[0003] in ray co-peiidmg psmnt application No 2013/03735

(WO 2012/058699) I have, described and iliastrated a military 'projector comprisirig a tukikr housing that cont ins a high &Bsit laffip _i: a .reflecting- mirror e isd ^" the high feieiisity lamp, a negative lens, fee form of a biconcave leas, which is located before the lamp and a pair of positive meniscus lenses spaced trom the negative lens and located near the front of fee-housing.

[0004] I have now made improvements or developments to this projector.

SUMMARY OF THE INVENTION

[00051 According to ohe aspect of the present iuveeiion. there is provided a military projector comprising a tubpkr housing that contains a high intensity lamp, a. reflecting mirror behind and preferably forming, a -part of the high intensity lamp, a negative lens which is carried a first mounting. member located in front of the lamp and a pair of positive meniscus leases which are laotrated in & second mounting member spaced from the negative lens cbaracterised m that the second mnt g mem er is capable of ein mpved relative to the first moaatiog member so that the distance between the negative tern and the posi ive meniscus lenses can be varied.

[0006] Preferably hoik the mooti members are cylindrical or have parts wfelcl. are cylindrical and are capable of relative roiatioa, preferably ιρ second moiiutisg member being rotatsbte relative to the first mountin niembet, asd there is provided cam and cam follower seaM eoaasctirig the two roo Ei jg members- so Ehat when there h relative rotation between the mohhtmg members, the second iBoa thig emher will he moved, towards or away from- the first mo.ttnsmg rrtember. in this way the cone angle af (he light beam emitted by the .projector can be varied. The earn and cam followe member preferably comprise- ^' ¾ plurality of preferably four) cams aid. a piaraiit of cam followers respectively engaging -the cams. _. The caais are .preferabl c m grooves forme to -be -first, mounting member and die sa - followers are piss carried by the second mounting me be ,

[0007] Preferably a toothed part is mounted on. the second mounting, member and a -pimpfc. engages this toothed part, the pmioa bein rota-table by a motor ("the adjusting motor") to rotate the second mountin member. The rotation of the second mounting member is preferably quite small. a«d preferably of the order of say 20". The- relative moveiae»i between the positive meniscus leases an the negative tens also is quite small being of die order of 7 mm. This wiil enable the projector to emit a beam which diverges either very slightly or a .little m e and thus can dinrnmate an area of about thirty five me res diameter at 10QO metres when the distance between the men scus lenses and the ne ative leas is at a maximum and about one hundred and five metres at 1000 metres when that distance is at mimnMtfn.

[0008] Preferably there is provided a filter carrier adapted to carry an infra-red filter, the filter carrier being pivoted- to the second mounting member so as. to pivot about a pivot between (i) an operative position in which the filter is in the path or rays passing through the meniscus lenses and (ii) an inoperative position outside d e said path, Moving member preferably including as. elecirie motor is provided to move the filter carrier from the operative to the inoperative position positions and vice versa. Preferably the filter carrier has a lever bei.Bg ivoted to a correc i g member at the other end of which is movahiy by an electric motor.

[0009] The high inten ity lamp is preferably a short arc Xenon ceramic lamp preferably ^' having an anode connector at one end and a cathode connector at the other.. A f s no mally provided to cool the lam in use. A mam heat sink ½ preferably also provided to keep the anode (or cathode) cool and a secondary heat sink is preferably also provided to keep the cathode (or anode) cool. T e two heat sinks are preferably spaced to prevent arcing,

[0910] An embodiment of the invention will now be described by way of example with reference to the accompanying drawings,

SHORT DESCRIPTION OF THE DRAWINGS

[001 i] In the. drawings. ·-

Figure 1 is a perspective view of a projector of the invention Figure 2 is a rear end view of d e projector;

Figure 3 is m imderview of the projector;

Figure 4 is a partially exploded longitudinal perspective section through the projector;

Figure 5 is a section oa ime 4 - 4 of Figure 2;

Figure 6 is a section os ime 6 - 6 of Figure 2;

Figure 7 is a longitudinal section through the lam holder,

Figure 8 is a frp&t. view o the lamp located m the heat sink.

Figure 9 is a rear perspective view of the lighting unit at?d the rear e¾d closure:

Figure 10. is a perspective view from the SO c ot the filter moviBg means; Figure 11 is a perspective detail, of an adjustable e»s carrier of the projector; Figure 1 is; a similar view of the rea holder;

Figure B is a similar ew sljowio the adjustable lens carrier mourned on the rear holder; and

Figure 14 is an enlarged detail of the piaios and rack,

$0012] Referring now to the drawings there is shown a military projector 10 of the is eRti a. The projector coaiprises a eoeiaimnent 100 within which is a light emittisg device,

[00013] The containment 100 consists of an extruded cylindrical aluminium housing 102 with a rear eud closure- member 104 aad a front annular end closure 106 which holds a glass closure disc 1.08. The housing 102 is 440 mm long and 185 mm outside diameter, ft has a wa f thickness of 3mm. [00014] Oil its exterior. i e housing 102 has four equkspaced enlarged longitudinally extending portions 110 within hic are formed respectively inverted outwardly opening T-shaped grooves 112 (see Figures 1 and 2). Equi- spaced between the portions 110 are four enlarged portions 114 with inwardly opening keyhole section slots 116.

[0Q015] The front en closure 106 has eight projecting lags ^' 120 which can be and are aligned, fo r with the portions 110 and four with the portions. 1141. Screws 122 passing through openings 124 (see Figure 4) in die lags 120 engage in the grooves 111 and the slats 116 to secure the f ont closure 106 to hold U on the front of the ^' housing 102. The rear end closure member 1.04 has fe projecting lugs 126 which caa be and are aligned with the enlarged portions 11 . Screws 128 passing through openings 129 m the lugs. 126 engage in .the .slots 116 to secure the end closure number 104 to the ^: rear end f the housing 102.

[00016] Eight substantially ova!o vnr*?. openings 13 are provided midway of the length of the housing 102, fOQQ!?} The rear end closure member 104 is an ahimhnum member. It has a if usto conical body 132 and a transverse plane surface 134 at its smaller end, An enlarged opening 136 passes through, this surface 134. The opening 136 is substantially circular with a chorda! flat 138. Surrounding the surface 134 in the body 132 are two sets of equally aligned cylindrical openings 140 of the same diameter arranged on two circles centered on the centre of the opening 336. There are Tour smaller holes 142 in the larger circle, The thickness of the body 132 b the same as the diameter of the opaaiugs 1.40, 90018] The end closure member 104 lias a cylindrical ei-d part 14 , the outer diameter of which is e same as that of the housing 102, he ead 146 of the end part is of reduced diameter so as to fit mto the end of the housisg 102.

$300.19] The torsi end closure 106 has a cylmdnc&i irmer. bore 148 which Increases at a 150 to a ma tere 152 (see Figures 4 and 5), The glass closure disc 108 rests on th step ISO an is held »¾ position by a circ!ip (not shown) fitting in a groove 1.54 i the mala opesiag 152,

[00020] The aiirmhiium housing 102 serves as an. eleetroroegBe-de harrier to eo«¾m the electro msgostlc radiation emanating fwm the lamp which mil be described below,

[00021 ]. A moimiing- bracket 156 (i l sho s in figures 2 and 3) is provided. The m thMiag bracket 156 comprises a base 158 and two elongated side arms 160, Plates (aot shown) fit la two adjacen grooves 1 12, Each plate has threaded apertures. Screws 1.64 pass ng through apertures at the arms ½0 engage in the threaded apertures in the plates to hold the bracket; 156 in position, By tigteumg the screws 164, the arms. 160 cati be damped between the material of the porhc-ns 1 10 at the groove 1 12 so drat the bracket 156 is secured firmly to the housing 102. The base 158 of the mourn ng bracket 156 has cat. out portions 162 to reduce weight. The base 158 can he modified as desired so thai the projector 10 can be rnonnted on to any apparatus, as is required, such as on a -machine gun.

[00022] ithiu the homing 102 is a light emitting device 200 (best shown i Figure 5), The light emitting device 200 comprises a mounting unit comprisin a front, disc like plate 202 and a rear disc plate 204 hich are located on. either side of the set of vent o ning 130 and extend to t e inner surface of the boas tag 102. The rear plate 204 is secured to the back end closure 104 by four square smioh ^' osts 206 which have t ned rear ends 207 of cyiind seal shape. hese feuds 20? pass through the .smalle . ©penisgs 142 where they are engaged by screws (aot shown) to secu e them to the rear end dMffi 104, 'T & f ont ends of th posts 206 have mtemaUy threaded: blind bores, Pour threaded membe s 208 (not shows) pass through small openings in the rear plate 204 (see Figure 4) and their rear ends engage la the blind ^" bares of fear rods 2X0 which extend to the front-plate 202, The front piste 202 is comprised by a flange of a f om cylindrical carrier member 214; This ^' member 214 has a large rear bore 216, a s ep 218 leading to the main bore part 220, aa a front bore part 222. An en ring 224 is secured to the end of Irani carrier member 214 by sc ews 225,

[0023] Carried by the mounting unit between the front and rear plates 202 and 204 is a lamp bossing 22S carrying a high intensity ceramic Xenon short arc lamp 228 (see Figure 7) having an integral parabolic reflector 230 and a .el ear front window 232, The window has a diameter of 12.7 m . (½ ").. e iamn and reflector will be described further below. [0024] A rear carrier member 234 is provided. The rear carrier member 234 has a rear bore 236 and a larger Imerrnedlaie bore 238 leading to conical section 240. A re&rwardiy extending cylindrical member 242 extends .from the end of rhe corneal section to flange 244, The edge of the flange 244 received in rear ore 216 of the &©nt carrier member 214 butting against the step 218 between the bores 216 and 220 and befog sealed thereto by an ^Λ Ο ^η ring .seal 246, A negative less m the form of a pkBO-eoacave lens 250 is monnied. in the rear bore 236, which ½ in front of the lamp 228, with ;the plane surface 252 closer to the lamp 228, A ring .254 basing ¾ry fine- threads is. th eaded irito the larger bore 23$ of the rear carrier member 234 which is correspondingly threaded to hold the less 250 in position. The. interior surface of the ring 254 has line nular grooves t prevent light being ^■ -reflected off this, surface.,

[0025] An intenrsediaie leas carrier 256 is located betwee the rear carrier .member 234 and the front carrier taerftber 214, The lens carrier 256 .has- .a raaia bore 258 whic fits on and is a !ly and rotatahiy slidahls -upon the rear cylindrical member 242, The relationship between the rear and .intermediate carriers 234 and 256 will be described farther below- The. front end of the carrier 256 has steps 259 and 360 to carry two: positive ffienlscHs tenses fcoacavc/convex lenses) 262 and 264 spaced closely apart, Cirdips 268 bold the lenses 262 and 26 in position. The axes of the lamp 228, the reflector 230 and the lenses 252 _» 262 and 264 are all aligned,

£0026] The inner meniscus teas- 262 has a diameter of 86 mm. Its rear concave surface 270 has a radius of 165,5 mm and its front convex surface 272 has a radius of 104, 81 inm. The distance of the deepest point of the .rear surface 270 ^' from the deepest point in the surface .274 of tae negative km 250 is 64.13 mm when tlie carrier 256 is in its rearmost position as will be described.

£GG2?3 The outer meniscus lexis 264 has a diameter of 92 mm. Its rear concave surface 276 lias a radius of 243,2 mat ami its front convex surface 27S has a radius of 87,54 mm. The distance of the deepest point of the rear surface 276 of the outer meniscus less 264 from the forwardmost point of the frost surface 272 of the moor lens 262 is 1 mm, p)28J in. fmM of the meniscus lenses 262 and 264 is a dear window 280 ftOimfed as will be described below,

[9029] A -main heat sink 280 having vanes 2S2 surrounds the rear end

^■ of the lamp. housing 282 surrounding- one of the terminals of tiie lamp. Spaced from the main .beat sink 280 is a frost heat sink 284 havin vanes 286. The fro heat sink 284 surrounds th other terminal of the lamp housing, {0030] A 288 is carried in a - ^' housing 290 (best sho n in Figure 10) secured to the plate 204. In use the fan 288 draws air in through- openings 140 the end closure .104 and: blows the air over the vanes 282 and 286 of the heat sinks 280 and 284, The air the escapes through the ve t openings 130. The -front and rear plates 202 and 294 serve as baffles which prevent the air passing for amly of the front plate 202 and reatwardly of the rear plate 204, 0031 Four cam slots 292 (best shown in Figure 12) are provided in the outer surface o ^' the rear cylinder 242. The cam slots 282 are inclined to a pirns normal to the axis of the rear cylinder 242 extending towards the upper end of the cylinder 242.

[0032] Four pins 294 pass through the iens carrier 266 and engage in the cam slots 292 to xotm cam followers.

.[003.3] A short areaaie gear rack 300 is mounted oa a portion of the surface of the lens carrier 266 (see Figure 12). Aa -elongated pinion 302 mss&es with this rack 300. The pinion 302 is carried cm a short shaft 304 extendin rearwacd y thereof and being fitted into bearings 306 and 308 in a cylindrical carrier 310 winch fits in ah opening 312 the --front plate 202. The rear end of the shaft 304 esters a hollow insulated drive shaft 314 (hereinafter called the ''adjnsthig ¹ shaft ^* ) that exisads ^' between the front plats 202 and. e. rear plats 204. Th shaft 314 is connec e to a coupling memher 316 which engages the drive shaft 318 of an electric motor 320 (hereinafter called the "adjusting motor") mounted on two posts 206. The djustin motor 320 is operable to rotate the pinion 302 so as to rotate the less carrier 266 relative to the rear carrier member 234. The earn followers 294 will then move hi the cam slots 292 to move the lens carrier 266 axiaiiy for ardiy and baeicwardly. The lengt and inclination of the earn slots 292 is such that this -movement would be 7 aim. The axial length of the pinion 302 is sufficient to maintain engagement with the gear rack 300 daring its full axial movemen

[0034] A filter carrier 324 is provided, it is pivoted cm a pivot pin 326 carried between a pair ©flags 328 carried by the end ring 224. The filter carrier 324 carries an Ma-red filter 330 which is slightly larger than the window 280. The filter 3 0! rests against a step m the filter carrier 324 and W

is held in position by a circHp (not shown). The filter carrier 324 can pivot about the pivot pin 326. (i) An operative position (as shown, in Figures 5 and 6) is which it lies against the end ring 224 and. (u) an open position in which it lies in- a plane parallel to the xis of the lenses 262 and 264. When the filter carrier 324 is m the operative position light passing through the lenses is filtered through the infra-red filter 330. When the titer carrier 324 is in the open, position the ligh from the lenses passes beside the filter carrier 324 and is uninterrupted,

[0035! A pair of pins 332 and 334 (see Figure 10} -extending-. arallel to the pivot pin 326 project from the end ring 224 and the filter carrier 324. Am. over centre, spring 336 joins these pins 332 and 334 to bias the filter carrier 324. into either operative position or its inoperative position.

£0036] A short lever 33S is provided on the filter carrier 324 radial to the pivot pin. 326. The end of the Sever 338 is pivotalry connected to a narrow rectangular section connecting rod 348, The rod 34 that passes through radial slots 342 and 344 in the plates 202 and 204. The other end the rod 340 is pivotaliy connected to a similar lever 346 movable by an electric motor 348 also mounted on the posts 206 (hereinafter called "the. filter motor").

[0037] Electronic control devices 350 mounted on a PCB 352 carried by two posts 206, are provided on the rear side of the rear plate 204 to operate the lamp 226. and the adjusting and filter motors 320 and 334. Suitable switch means (not shown) are provided to operate the control devices to operate the lamp 226 and the adjusting and filter motors 320 and 334. These .de ices receive- ower from a cable- {not shown) connected to a power pack or control box outside the projector 10. Th cable eaters the projector 10 through, a ■.union 354 passing through, the opening 136 at the centre of the conical end piece 104, If desired the power pack or control box can be quite remote from the projector - which mig t be mounted on a mast or the like.

[0038] As mentioned, above the lamp 266 has a reflecting mirror 230 behind it . The mirror 230 is parabolic in shape, it is arranged to reflect a spectrins of 2QQn (IJV) to 1 lOfem (NIK), The lamp optical system, i. e. the high, intensity lamp 266, parabolic mirmr 230 and lamp window 23% delivers radiant power, on offer by in a beam with the following. characteristics viz an approximately Gaussian shaped Intensity profile; a total angular spread i radiant power, at the 10 % of maximu oin s, of 9" - 12°; projection of he radiant source of a very long distance say 1 OQSm to 200Q;½ or more. The characteristics, of the negative lens 260 being radii, thickness, glass types and airspaces, and designed to ..condition the beam in the fal lowing ways he, to retain the Gaussian slvaped inteiisiij' profile of the jarnp system; to .reduce: fee total angular spread by a factor of 3 - 4X nmirnum; and to allow adjustment of the- ^' angular spread ^' without loss of ^' the intensity profile shape, All three lenses 250, 262 and 264 are manufactured from ¾e high refractive index, raid dispersion G angmlug H-LAF52 glass. Lens spacings are normally specified on the optical axis, e.g. the airspace between surface 274 of negative lens 250, and: surface 270 of lens 262 is 64, Buna along the optical axis.

[0039] It will be seen that the lenses are fn two groups have a. common focal point which s a Galilean telescope arrangement. The described arrangement reduces beam divergence as well as other optical abberations ars when the positive lens 262 .gad 264 are spaced, at a .tsaximnna from the negative .less a very powerful narrow beam, witfc a high energy density to be projected over a great distance which may be a diaiteier of 35 metres over 1000 metres.

[0040] It ili ^; In addition be seen that by operating the adjusting- motor 320, to move the lenses closer togetiier the beam to be projected can be varied between the very .narrow beam as mentioned aboste to a (comparatively) broad eam i -. lti-minate an area, of one hundred meters diameter at 1000 metres. f¾0 !] Itwi!l ¾fher be seen that by operating the filter rnstor: 348 the: projector M may be used with. visible l g t or inrm^ed. light th t has passed through art iafra-red filter.

|0042} Th invemkmis sot limited to the precise constructional details hereinbefore described and Illustrated in the drawings, Eor exam le the negative leas may be- a hl-eoneave less. The various: sizes and spaces mentioned may he varied. The enclosure 106 may be opes or may carry a plane glass window to protect the interior of the projector. Although the projector, is referred to herein m a military projector it may be used for other non-mhitary purposes.