Background of the Invention

The present invention relates to a fitting for locating a lamp in a plurality of positions relative to the focal point of a lamp reflector.

In many applications, reflector arrangements producing different beam angles and intensities are required to provide desired effects.

In conventional lamps, such as glass PAR (Parabolic Aluminized Reflector) lamps used for example in stage lighting, the lamp is fixedly mounted in a reflector body and thus it is not possible to vary the beam angle and intensity. Rather, if a different beam angle and intensity is required the lamp has to be replaced.

Lamp holders which provide for axial adjustment of a lamp and reflector for focusing purposes are known for example in GB-272,653 and FR- 1 ,004,706. However, the prior art lamp holders which provide for axial adjustment of the position of a lamp in a reflector do not permit a lamp to be located repeatedly and accurately in a plurality of set predetermined positions within a reflector.

An aim of the present invention is to provide a low cost, simple fitting for a lamp reflector which allows a lamp to be located repeatedly and accurately in a plurality of predetermined positions relative to the focal point of the lamp reflector and thus provide an output beam having different set beam angles and intensities.

It is a particular aim of the present invention to provide a fitting for a lamp reflector which allows a lamp to be located repeatedly and accurately in a plurality of predetermined positions relative to the focal point of the lamp reflector with minimum shock to the lamp. It is known that lamp filaments are extremely fragile at operating temperature and thus in order to prolong the life of any lamp it is necessary to minimise shock to the lamp.

Summary of the Invention

The present invention provides a fitting for a lamp and reflector, comprising: a frame assembly, one end of which is in use connected to a reflector; a member disposed to the frame assembly to which a lamp is in use mounted, said member being axially displaceable; and a position setting element coupled to said lamp support member; wherein said frame assembly is provided with at least one detent or a plurality of spaced openings and said position setting element includes the other of the at least one detent or the plurality of spaced openings; whereby axial positioning of the lamp support member in relation to the frame assembly is effected by movement of the position setting element and locating the at least one detent in one of the plurality of spaced openings.

In a first preferred aspect the present invention provides a fitting for a lamp and reflector, comprising: a main frame assembly, one end of which is in use connected to a reflector; a member disposed within the main frame assembly to which a lamp is in use mounted, said member being axially displaceable; a supporting element disposed to the main frame assembly and

including at least one detent or a plurality of axially spaced openings; and a position setting element coupled to the lamp support member and including the other of the at least one detent or the plurality of axially spaced openings; whereby axial positioning of the lamp support member in relation to the main frame assembly is effected by movement of the position setting element and locating the at least one detent in one of the plurality of axially spaced openings.

In another preferred aspect the present invention provides a fitting for a lamp and reflector, comprising: a frame assembly, one end of which is in use connected to a reflector, said frame assembly including at least one detent or a plurality of circumferentially-spaced openings; a position setting element including the other of the at least one detent or the plurality of circumferentially-spaced openings, and a helical track or a radially-directed guide; an axially displaceable member disposed within the frame assembly to which a lamp is in use mounted, said member including the other of the helical track or the radially-directed guide; whereby axial positioning of the lamp support member in relation to the frame assembly is effected by movement of the position setting element and locating the at least one detent in one of the plurality of circumferentially- spaced openings.

This preferred lamp fitting, by not directly linking the detent to the lamp support member, provides an arrangement in which the shock applied to the lamp is minimised.

In a third preferred aspect the present invention provides a fitting for a lamp and reflector, comprising: a main frame assembly, one end of which is in use fitted to the neck section of a reflector; a member disposed within the main frame assembly to which a lamp is in use mounted, the lamp support member being axially displaceable and biased by a resilient means towards the one end of the main frame assembly; and an adjustment device comprising a supporting element provided by or to the main body and defining a plurality of axially spaced positions, and a position setting element attached to the lamp support member; whereby axial positioning of the lamp support member in relation to the main frame assembly is effected by locating the position setting element at one of the axially spaced positions.

The supporting element is preferably a stepped plate, each step having a height corresponding to a predetermined axial displacement of the supporting member relative to the main frame assembly.

Brief Description of the Drawings

Preferred embodiments of the present invention will now be described hereinbelow by way of example only with reference to the accompanying drawings, in which:

Figure 1 shows an exploded side view of a lamp fitting in accordance with a first preferred embodiment of the present invention mounted to a lamp reflector;

Figures 2(a) to (d) show rear end, side, forward end and plan views of

one side frame part of the main frame assembly of the lamp fitting of Figure 1 ;

Figure 3 shows a plan view of the clamping plate of the lamp fitting of Figure 1 ;

Figure 4 shows a plan view of the light shield of the lamp fitting of Figure

1 ;

Figures 5(a) to (c) show side, bottom and end views of the lamp support member of the lamp fitting of Figure 1 ;

Figures 6(a) to (c) show plan and side views of the supporting element of the adjustment device of the lamp fitting of Figure 1 ;

Figures 7(a) and (b) show plan and side views of the adjustment knob of the lamp fitting of Figure 1 ;

Figures 8(a) and (b) show side and plan views of the insert for the adjustment knob of the lamp fitting of Figure 1 ;

Figure 9 shows a first side view of a lamp fitting in accordance with another preferred embodiment of the present invention mounted to a lamp reflector;

Figure 10 shows a second side view ofthe lamp fitting of Figure 9 (when viewed along direction X);

Figure 11 shows a vertical longitudinal section of the lamp fitting of Figure 9;

Figure 12 shows an exploded view from the first side of the lamp fitting of Figure 9;

Figures 13(a) to (d) show rear end, side, forward end and plan views of one side frame part of the main frame assembly of the lamp fitting of Figure 9;

Figures 14(a) and (b) show plan and side views of the clamping plate of the lamp fitting of Figure 9;

Figures 15(a) to (c) show side, plan and end views of the lamp support member of the lamp fitting of Figure 9;

Figures 16(a) to (c) show plan and side views of the supporting element

of the adjustment device of the lamp fitting of Figure 9;

Figure 17 shows a plan view of the light shield of the lamp fitting of Figure 9;

Figures 18A(a) and (b) show bottom and side views of the detent assembly of the lamp fitting of Figure 9;

Figure 18B shows a side view of the detent of the lamp fitting of Figure 9;

Figures 19(a) and (b) show side and end views of the supporting shaft of the adjustment knob of the lamp fitting of Figure 9;

Figure 20 shows an exploded plan view of the main frame assembly, light shield, detent mounting plate, lamp support member and connecting spacer of the lamp fitting of Figure 9;

Figures 21(a), (b) and (c) show side, plan and end views of the guide member of the lamp fitting of Figure 9;

Figures 22(a) and (b) show side and end views of one guide stud of the lamp fitting of Figure 9;

Figures 23(a) and (b) show plan and side views of the adjustment knob of the lamp fitting of Figure 9;

Figures 24(a) and (b) show side and plan views of the insert for the adjustment knob of the lamp fitting of Figure 9;

Figure 25 shows a cross-sectional view of a preferred lamp reflector for use with the lamp fitting of the present invention.

Figure 26 shows a side view of a lamp fitting in accordance with a yet further preferred embodiment of the present invention;

Figure 27 shows a plan view of the lamp fitting of Figure 26;

Figures 28(a) to (d) show plan, rear end, side and forward end views of the main frame of the lamp fitting of Figure 26;

Figures 29(a) to (d) show end, bottom side and plan views of the lamp support member of the lamp fitting of Figure 26;

Figures 30(a) to (c) show end, plan and side views of the index plate of the lamp fitting of Figure 26;

Figure 31 shows a plan view of the light shield of the lamp fitting of Figure 26;

Figure 32 shows a plan view of the index arm of the lamp fitting of Figure 26;

Figures 33(a) and (b) show plan and side views of the adjustment knob of the lamp fitting of Figure 26;

Figure 34 shows an exploded plan view of the lamp fitting of Figure 26; and

Figure 35 shows an exploded plan view of the lamp socket support unit of the lamp fitting of Figure 26.

Detailed Description of Preferred Fmbodiments

Figures 1 to 8 show a lamp fitting in accordance with a first embodiment of the present invention.

The lamp fitting 1 includes a main frame assembly which in this embodiment is mounted to the neck section of the lamp reflector 5. Alternatively, the main frame assembly can be coupled to another part of the lamp reflector 5 or to another component which in use is attached to the lamp reflector 5. For example, when the lamp reflector 5 is fitted in a tubular section (e.g. a PAR can), the main frame assembly can be attached to the tubular section and thereby indirectly to the lamp reflector 5. The main frame assembly comprises two identical side frame parts 7 which are disposed on opposed diametral sides of the neck section of the lamp reflector 5. Each side frame part 7 is of a substantially U-shaped section and has a flat web 7a and arms 7b,7c extending orthogonally from each longitudinal end thereof. One

(first) arm 7b, which is of shorter length and greater width than the other (second) arm 7c, has a truncated semi-circular cut-out 9 formed at the free edge thereof. This cut-out 9 conforms to the outer shape of the neck section of the lamp reflector 5. The side frame parts 7 are fastened to the neck section of the lamp reflector 5 by a clamping plate 11 and threaded screws 15. The clamping plate 11 is a square plate which has a centrally-located hole 17 formed therein corresponding to the intemal diameter of the neck section of the lamp reflector 5 and clearance holes 19 located adjacent each corner thereof. The clamping plate 11 is preferably formed from 0.06 inch (15.24 mm) aluminium plate with a black anodized finish. The screws 15 are located through the clearance holes 19 in the clamping plate 11 and are received in correspondingly positioned and threaded holes 21 in the first arm 7b of each side frame part 7. The second arm 7c of each side frame part 7 has a preferably semi-circular cut-out 23 formed at the mid-point of the free edge thereof. In the assembled configuration the free edges of the second arms 7c abut one another, whereby the semi-circular cut-outs 23 define-a substantially circular opening. The second arms 7c each further include two clearance holes 25 which are located adjacent, preferably symmetrically, the semi¬ circular cut-outs 23. Alternatively, the main frame assembly can be formed form a single frame part which corresponds in overall shape to the side frame parts 7 when joined along the free edges of the second arms 7c. With this latter configuration the main frame assembly is fitted to the neck section of the reflector 5 by splaying open the first arms 7b.

The lamp fitting 1 includes a light shield 27, which in this embodiment is a circular plate, disposed adjacent the rearwardly-directed surface of the second arms 7c of the side frame parts 7. The light shield 27 has a central hole 29 and four smaller clearance holes 31 located therearound which are correspondingly positioned to the clearance holes 25 formed in the second

arms 7c ofthe side frame parts 7. The light shield 27 is preferably formed from 0.06 inch (15.24 mm) aluminium plate with a black anodized finish and acts to shield the rearwardly-disposed components of the lamp fitting 1 from light radiation which is transmitted through the neck section of the lamp reflector 5.

The lamp fitting 1 further includes a U-shaped support member 33 for holding a socket (not shown) for a lamp. The support member 33 is disposed within the main frame assembly so as to be movable axially therewithin. The support member 33 comprises a flat web 33a having an upstanding arm 33b at each of its longitudinal ends, which member 33 is so adapted that the upstanding arms 33b locate against the inner surfaces of the webs 7a of the side frame parts 7. Each upstanding arm 33b includes a radially outwardly projecting lug 35 disposed at the mid-point of the distal end thereof. The projecting lugs 35 are located in complimentary slots 37 provided in the webs 7a of the side frame parts 7 so as to align the support member 33 along the longitudinal axis of the lamp fitting 1. The lamp socket is disposed within the support member 33 and is fixed thereto by bolts (not shown) which pass through the body of the lamp socket and are located in threaded holes 39 provided in the web 33a of the support member 33. The web 33a of the support member 33 has on its rear side a threaded stud 41 which extends orthogonally to the plane of the web 33a. In this embodiment, the threaded stud 41 extends from the centre of the web 33a, i.e. along the longitudinal axis of the main frame assembly. A connecting spacer 43, which has a correspondingly threaded bore, is attached to the threaded stud 41. The connecting spacer 43 passes through the central opening 29 in the light shield 27. A shoulder washer 42, preferably made of TEFLON (registered trade mark), is disposed in the central opening 29 in the light shield 27 so as to prevent metal-to-metal contact. The position of the connecting spacer 43 on the threaded stud 41 can be fixed by a lock nut (not shown) in a conventional

manner. As an altemative to this arrangement, the connecting spacer 43 may simply be fixed directly to the web 33a of the lamp support member 33 by means for example of a weld.

The lamp fitting further includes an adjustment device which comprises a support element 47 and an adjustment knob 49. The support element 47 is preferably formed of 0.06 inch (15.24 mm) aluminium sheet with a black anodized finish and the adjustment knob 49 is preferably formed of a plastics material, e.g. DELRIN (a registered trade mark).

The support element 47 is disposed to the rearwardly-directed surface of the light shield 27, and is fixed to the light shield 27 and the second arms 7c of the side frame parts 7 by pop-rivets 51. It will be understood that other means of attachment such as threaded bolts could alternatively be used. The support element 47 comprises an octagonal base plate 53, which has a central, preferably circular, opening 54 and four smaller clearance holes 55 located therearound through which pass the pop-rivets 51 , and upstanding arms 56,57,59 which extend from three sides of the base plate 53 spaced 90° apart. First and second arms 56,57 are disposed on opposed sides of the base plate 53 and each have a preferably circular hole 61 formed adjacent the free end thereof. The third arm 59 has a projection 63 extending outwardly from the free end thereof. The projection 63 has a V-shaped notch 65 formed at the longitudinal edge thereof. A detent mechanism 67 is located in each of the openings 61 defined in the first and second arms 56,57 of the support element 47. The detent mechanisms 67, which comprise a detent 69 spring- mounted in a casing 71 , are inwardly directed and adapted to engage correspondingly formed parts of the adjustment knob 49 as will be described hereinbelow. The casing 71 of each detent mechanism 67 has a, preferably circular, face plate which is located against a respective inner face of the first

and second arms 56,57 of the supporting element 47.

The adjustment knob 49 comprises a cylindrical main body 73 having pairs of diametrally opposed openings 75a-g defined at axially-spaced positions on the outer side surface thereof. In this embodiment the openings 75a-g are truncated hemi-spherical recesses and are defined in helical tracks 77 symmetrically disposed on the outer surface of the main body 73. The helical tracks 77 comprise blind slots having the openings 75a-g formed therealong with centre to centre spacings of 14° intervals. The slots have a width and a depth corresponding respectively to the diameter and thickness of the face plate of each detent mechanism 67. ln this way the face plates of the detent mechanisms 67 are held captive in the respective slots, thereby allowing the detents 69 to be guided into any of the respective pairs of openings 75a-g by simply rotating the adjustment knob 49. Without such slots the positioning of the detents 69 in respective pairs of the openings 75a-g would be difficult since no means for guiding the detents 69 to the openings 75a-g would be provided. The adjustment knob 49 further comprises a head part 79 which is that part that is gripped when the adjustment knob 49 is to be rotated to provide adjustment of the position of the lamp in the reflector 5. The head part 79 has a maximum diameter greater than that of the main body 73 and for improved grip is provided with recesses on the outer edge thereof. With this arrangement, the notch 65 formed in the outwardly-extending projection 63 of the third arm 59 ofthe support element 47 is visible beyond the outer edge of the head part 79 and thereby permits the set position of the adjustment knob 49 to be determined easily. The adjustment knob 49 is fixed to the connecting spacer 43 by a threaded screw 85 and has a circular insert 87 located in the head part 79. The insert 87 has two clearance holes 89 formed axially therethrough and is fixed to the adjustment knob 49 by threaded screws 91 which pass through the holes 89 and are received in

correspondingly-positioned threaded holes 93 in the adjustment knob 49. The insert 87 can carry information such as the position settings of the lamp in the lamp reflector 5 attainable by the lamp fitting 1.

In use, the position of the support member 33 and hence the lamp in the lamp reflector 5 can be altered by rotation of the adjustment knob 49. In this embodiment, rotation of the adjustment knob 49 in a clockwise direction causes the adjustment knob 49 and the attached support member 33 to be moved axially in a direction into the lamp reflector 5 relative to the focal point of the lamp reflector 5 (i.e. right to left in Figure 1 ). In the extreme position of clockwise rotation the spring-mounted detents 69 are located in the openings 75a. Rotation of the adjustment knob 49 in an anti-clockwise direction causes the adjustment knob 49 and the attached support member 33 to be moved axially out of the lamp reflector 5 relative to the focal point of the lamp reflector 5 (i.e. left to right in Figure 1 ). In the extreme position of anti-clockwise rotation the spring-mounted detents 69 are located in the openings 75g. In this way, the lamp can be repeatedly set with accuracy at any one of seven positions along the optical axis of the lamp reflector 5 by locating the detents 69 in one of the respective pairs of openings 75a-g. It will be understood that the adjustment knob 49 can be provided with any number of openings 75 according to the number of positions which it is desired to set the lamp in the reflector 5.

Figures 9 to 24 show a lamp fitting in accordance with a second embodiment of the present invention.

The lamp fitting 101 includes a main frame assembly which is mounted to the neck section of a lamp reflector 105. Altematively, as with the above- described embodiment, the main frame assembly can be coupled to another

part of the lamp reflector 105 or to another component which in use is attached to the lamp reflector 105. The main frame assembly comprises two identical side frame parts 107 which are disposed on opposed diametral sides of the neck section of the lamp reflector 105. Each side frame part 107 is of a substantially U-shaped section and has a flat web 107a and arms 107b, 107c extending orthogonally from each longitudinal end thereof. One (first) arm 107b, which is of shorter length and greater width than the other (second) arm 107c, has a truncated semi-circular cut-out 109 formed at the free edge thereof. This cut-out 109 conforms to the outer shape of the neck section of the lamp reflector 105. The side frame parts 107 are fastened to the neck section of the lamp reflector 105 by a clamping plate 111 and threaded screws 115. The clamping plate 111 is formed from a rectangular plate and comprises a first, main part 111a and a second, minor part 111 b which is bent at 45° to The main part 111a. The first, main part 111 a of the clamping plate 111 has a hole 117 formed therein corresponding to the internal diameter of the neck section of the lamp reflector 105 and clearance holes 119 disposed symmetrically in square relation about the hole 117. The second part 111 b of the clamping plate 111 serves as a support for an electrical connector 112 for the lamp. The clamping plate 111 is preferably formed from 0.06 inch (15.24 mm) aluminium plate with a black anodized finish. The screws 115 are located through the clearance holes 119 in the clamping plate 111 and are received in correspondingly positioned and threaded holes 121 in the first arm 107b of each side frame part 107. The second arm 107c of each side frame part 107 has a preferably semi-circular cut-out 123 formed at the mid-point of the free edge thereof. In the assembled configuration the free edges of the second arms 107c abut one another, whereby the semi-circular cut-outs 123 define a substantially circular opening. The second arms 107c each further include two clearance holes 125 which are located adjacent, preferably symmetrically, the semi-circular cut-outs 123. Altematively, again as with the above-described

embodiment, the main frame assembly can be formed form a single frame part which corresponds in overall shape to the side frame parts 107 when joined along the free edges of the second arm 107c.

The lamp fitting 101 includes a light shield 127, which in this embodiment is a circular plate, disposed adjacent the rearwardly-directed surface of the second arms 107c of the side frame parts 107. The light shield 127 has a central clearance hole 128 and four smaller clearance holes 131 located therearound which are correspondingly positioned to the clearance holes 125 formed in the second arms 107c of the side frame parts 107. The light shield 127 further has two diametrally opposed openings 132 through which, as will be described in detail hereinbelow, arms 134b of a guide plate 134 are disposed. The light shield 127 yet further has a pair of clearance holes 129 formed adjacent its circumferential edge and a further clearance hole formed close thereto. The light shield 127 is preferably formed from 0.06 inch (15.24 mm) aluminium plate with a black anodized finish and acts to shield the rearwardly-disposed components of the lamp fitting 101 from light radiation which is transmitted through the neck section of the lamp reflector 105.

The lamp fitting 101 further includes a support unit for holding a socket 106 for a lamp. The lamp support unit comprises a support member 133 and a guide member 134. The lamp support unit is disposed within the main frame assembly so as to be movable axially therewithin. The support member 133 comprises a substantially U-shaped main body having a flat rectangular base 133a with an upstanding arm 133b at the mid-point of each of its longitudinal edges, which member 133 is so adapted that the upstanding arms 133b locate against the inner surfaces of the webs 107a of the side frame parts 107. Each upstanding arm 133b includes a radially outwardly projecting lug 135 disposed at the mid-point of the distal end thereof. The projecting lugs 135 are located

in complimentary slots 137 provided in the webs 107a of the side frame parts 107 so as to align the support member 133 along the longitudinal axis of the lamp fitting 101. The lamp socket 106 is disposed within the support member 133 and is fixed thereto by bolts 106a which pass through the body of the lamp socket 106 and clearance holes 139 provided in the base 133a of the support member 133 and are located in threaded holes 140 provided in the web 134a of the guide member 134. The supporting member 133 further includes a part 133c, bent at an angle of 45°, disposed to one end of the base 133a of the support member 133. The purpose of the extended base 133a and the additional part 133c is to provide a sink for the heat generated in use by the lamp. The guide member 134 is fixed to the rearwardly-directed surface of the base 133a of the support member 133. The guide member 134 comprises a flat web 134a with an upstanding member 134b at each of its longitudinal ends. The upstanding arms 134b are of narrower width than the web 134a of the guide member 134. Each upstanding arm 134b includes an opening 134' near the distal end thereof. The openings 134' are dimensioned to each receive a guide stud 167 with an interference fit. The guide studs 167 have an enlarged head 167a, which as will become apparent hereinbelow, act as followers.

The lamp fitting 101 further includes an adjustment device which comprises a support element 147 and an adjustment knob 149. The support element 147 is preferably formed of 0.06 inch (15.24 mm) aluminium sheet with a black anodized finish and the adjustment knob 149 is preferably formed of a plastics material, e.g. DELRIN (a registered trade mark).

The support element 147 is disposed adjacent the light shield 127 and is fixed to the light shield 127 and the second arms 107c of the side frame parts 107 by pop-rivets 151. It will be understood that other means of attachment such as threaded bolts could alternatively be used. The support

element 147 comprises a truncated octagonal base plate 153, which has a central clearance hole 154 and four clearance holes 155 located therearound through which pass the pop-rivets 151 , and upstanding arms 156,157,159 which extend from three sides of the base plate 153 spaced 90° apart. First and second arms 156,157 are disposed on opposed sides of the base plate 153. The third arm 159 has a projection 163 extending outwardly from the free end thereof. The projection 163 has a V-shaped notch 165 formed at the longitudinal edge thereof. The base plate 153 of the support element 147 further has two diametrally opposed openings 160 through which, as will be described hereinbelow, arms 134b of a guide plate 134 are disposed.

The adjustment knob 149 comprises a cylindrical main body 173 having openings 175a-g circumferentially spaced at a fixed radial distance about the underside 173a of the main body 173. In this embodiment the openings 175a- g are truncated hemi-spherical recesses formed with centre to centre spacings of 14° intervals. The main body 173 further has a pair of diametrically opposed helical tracks 177 disposed on the outer side surface 173b thereof. The helical tracks 177 comprise slots having a width and a depth corresponding respectively to the diameter and thickness of the enlarged head 167a of each guide stud 167. In this way the enlarged heads 167a of the guide studs 167 are held captive in the respective slots. The adjustment knob 149 further comprises a head part 179 which is that part that is gripped when the adjustment knob 149 is to be rotated to provide adjustment of the position of the lamp in the reflector 105. The head part 179 has a maximum diameter greater than that of the main body 173 and for improved grip is provided with recesses on the outer edge thereof. With this arrangement, the notch 165 formed in the outwardly-extending projection 163 of the third arm 159 of the support element 147 is visible beyond the outer edge of the head part 179 and thereby permits the set position of the adjustment knob 149 to be determined

easily. The adjustment knob 149 is rotatably mounted on a connecting spacer 143 which is fixed to the support element 147 by a threaded screw 184. The adjustment knob 149 is fixed to the connecting spacer by a threaded screw 185. The adjustment knob 149 has a circular insert 187 located in the head part 179. The insert 187 has two clearance holes 189 formed axially therethrough and is fixed to the adjustment knob 149 by threaded screws 191 which pass through the holes 189 and are received in correspondingly- positioned threaded holes 193 in the adjustment knob 149. The insert 187 can carry information such as the position settings of the lamp in the lamp reflector 105 attainable by the lamp fitting 101.

The lamp fitting 101 further includes a detent assembly 190 which is mounted to the light shield 127. The detent assembly 190 comprises a mounting plate 191 having a detent 192 fixed thereto. The mounting plate 191 is U-shaped, with one (first) arm 191a, which is longer than the other (second) arm 191b, carrying the detent 192. The other arm 191b of the mounting plate 191 is provided with clearance holes 193 which are correspondingly positioned to the clearance holes 129 provided at the circumferential edge of the light shield 127. The mounting plate 191 is attached to the light shield 127 by pop- rivets 194. The detent 192 is rivetted to the first arm 191a and is so dimensioned as to extend beyond the flat outer surface of the second arm 191b, through the clearance hole 130 in the light shield 127, and engage a respective one of the openings 175a-g defined in the underside 173a of the main body 173 of the adjustment knob 149. The detent 192 is formed with a hemispherical distal end having a radius of curvature, preferably 0.094inch (2.388mm), corresponding to that of the hemispherical openings 175a-g in the adjustment knob 149. The detent 192 is preferably formed of brass. The mounting plate is formed from spring steel sheet, preferably 0.015inch (0.381mm) in thickness.

In use, the position of the support member 133 and hence the lamp in the lamp reflector 105 can be altered by rotation of the adjustment knob 149. In this embodiment, rotation of the adjustment knob 149 in a clockwise direction causes the support member 133 to be moved in a direction into the lamp reflector 105 relative to the focal point of the lamp reflector 105 (i.e. right to left in Figure 9). In the extreme position of clockwise rotation the spring- mounted detent 192 is located in the opening 175a. Rotation of the adjustment knob 149 in an anti-clockwise direction causes the support member 133 to be moved out of the lamp reflector 105 relative to the focal point of the lamp reflector 105 (i.e. left to right in Figure 9). In the extreme position of anti¬ clockwise rotation the spring-mounted detent 192 is located in the opening 175g. In this way, the lamp can be repeatedly set with accuracy at any one of seven positions along the optical axis of the lamp reflector 105 by locating the detent 192 in one of the openings 175a-g. It will be understood that a lamp fitting can be provided with a second set of openings having a spacing corresponding to the openings 175a-g together with an associated detent arrangement. The provision of a second detent arrangement provides a fail¬ safe in the event that the first detent arrangement fails. It will further be understood that the adjustment knob 149 can be provided with any number of openings 175 according to the number of positions which it is desired to set the lamp in the reflector 105.

Figures 26 to 35 show a lamp fitting in accordance with a third embodiment of the present invention.

The lamp fitting 201 includes a main frame assembly 203 which is mounted to the neck section of a lamp reflector 205. Plan, side and end views of the main frame assembly 203 are shown in Figures 28(a) to (d). The main

frame assembly 203 is of square-section (see Figure 28(c)) and includes a substantially circular opening 207 in one end member, the forward end member, which receives the neck section of the lamp reflector 205. Those parts 207' of the forward end member which are on opposed diametral sides of the circular opening 207 are removed so as to allow the side members 203a,b of the main frame assembly to be splayed open and thereby permit the main frame assembly 203 to be located about the neck section of the lamp reflector 205. One ofthe side members 203a of the main frame assembly 203 includes two threaded holes 209, each of which is located adjacent a respective outer edge of that side member 203a and the forward end of the main frame assembly 203. The other side member 203b includes two correspondingly located clearance holes (not shown). In use, bolts 211 pass through the clearance holes in the other side member 203b and are received in the threaded holes 209 in the opposing side member 203a. This arrangement permits, by tightening of the bolts 211 , the main frame assembly 203 to be fastened to the neck section of the lamp reflector 205.

The lamp fitting 201 further includes a support unit 215 for holding a socket 216 for a lamp 217. The lamp support unit 215 comprises an attachment plate 218 and a U-shaped support member 219 which is mounted to the front side of the attachment plate 218. The lamp support unit 215 is disposed within the main frame assembly 203 so as to be movable axially therewithin. The support member 219 comprises a flat web 219a having an upstanding arm 219b at each of its longitudinal edges, which member 219 is so adapted that the upstanding arms 219b locate against the inner surfaces of the side members 203a,b of the main frame assembly 203. The upstanding arms 219b each include a radially outwardly projecting lug 225 which is disposed centrally at its distal end. The projecting lugs 225 are located in complementary slots 227 provided in the side members 203a,b of the main

frame 203 so as to align the lamp support unit 215 along the longitudinal axis of the lamp fitting 201. The lamp socket 216 is disposed within the support member 219 and is fixed thereto by bolts 228 which pass through the body of the socket 216 and are located in threaded holes 229 provided in the flat web 219a of the support member 219. The attachment plate 218 has on its rear side a threaded stud 222 which extends normally to the plane thereof. In this embodiment the stud 222 extends from the centre of the attachment plate 218, i.e., along the longitudinal axis of the main frame assembly 203. A connecting spacer 223, which has a correspondingly threaded bore, is attached to the threaded stud 222. This threaded coupling of the spacer 223 to the attachment plate 221 provides for adjustment of the position of the lamp support unit 215 in relation to the main frame assembly 203 prior to attachment of the fitting. The position of the connecting spacer 223 on the threaded stud 222 is fixed by a lock nut 224 in a conventional manner. As an altemative to this arrangement the connecting spacer 223 may simply be fixed directly to the attachment plate 218, for example by a weld, or indeed the attachment plate 218 may be omitted entirely and the connecting spacer 223 fixed to the web 219a of the supporting member 219.

The lamp fitting 201 further includes an index plate 231 which is fixed, for example by pop-rivets, to the other end member, the rear end member, of the main frame assembly 203. The index plate 231 is shown in Figures 30(a) to (c). The index plate 231 comprises a channel-shaped member which in this embodiment is disposed such that its longitudinal axis is located along the longitudinal axis of the rear end member of the main frame assembly 203. The index plate 231 could however equally be arranged with its longitudinal axis at any angle to the longitudinal axis of the rear end member of the main frame assembly 203. The arms 231 a,b of the index plate 231 are stepped along their entire length, with the height of the steps on one arm 231a decreasing and the

height of the steps on the other arm 231b increasing in a symmetrical fashion when viewed in the same direction. The index plate 231 has rotational symmetry and each of the corresponding steps on the two arms 231 a, b is of the same height. At the mid-point along the longitudinal length of the index plate 231 the height of the steps on each of the arms 231 a,b is the same. In this embodiment, each of the arms 231 a.b includes seven steps A-G. The web or base of the index plate 231 has an opening 232 at the mid-point along its longitudinal axis which receives a shoulder washer 233, preferably made of TEFLON (registered trade mark), though which the connecting spacer 223 passes. A light shield 234 is also provided between the main frame assembly 203 and the index plate 231. The light shield 234 has a central opening 235 which receives the flange of the shoulder washer 233. In this embodiment, the light shield 234 is a circular member which has a diameter greater than that of the length of the index plate 231 and the rear end member of the main frame assembly 203.

The lamp fitting further includes an index arm 236 (see Figure 32) which is attached in a freely rotatable manner to that end of the connecting spacer 223 which is remote from the lamp support unit 215. The index arm 236 comprises a plate 237 having a central hole 238 though which the connecting spacer 223 passes and two opposed radially outwardly directed arms 239. A knob 240 is fixed on the rear side of the plate 237, preferably by screws 241 , so as to facilitate adjustment of the angular position of the index arm 236, that is the location of the arms 239 on a corresponding pair of the steps A-G of the index plate 231 , and hence the axial position of the lamp support unit 215 within the main frame assembly 203. Preferably, the knob 240 is fabricated from DELRIN (registered trade mark) and has a knurled outer edge. The index arm 236 and knob 240 are held captive at the end of the connecting spacer 223 by a threaded bolt 243 which is engaged in the threaded bore of the

connecting spacer 223. The bolt 243 has an enlarged head over which the index arm 236 and knob 240 cannot pass. The radially extending arms 239 of the index arm 236 are so adapted as to be locatable on a corresponding pair of the steps A-G of the index plate 231. When the arms 239 are located on steps A the lamp support unit 215 and hence the lamp 217 is positioned in a foremost position within the lamp reflector 205. Figure 28 shows the index arm 236 located in the central position, i.e., on step D. In order to accommodate the effective increase in the width of the arms 239 with increasing angle of rotation from the central position, either to the steps A of smallest height or to the steps G of greatest height, the steps are formed so as to have increasing length from the central step outward. A resilient element 244, for example a compression spring, is disposed between the rear end member of the main frame assembly 203 and the attachment plate 218 of the lamp support unit 215 so as to bias the lamp support unit 215 in the forward direction and hence maintain the lamp 217 in a set position within the lamp reflector 205.

In the above-described embodiments any commercially available lamp socket which is adapted to accommodate incandescent or arc discharge lamps can be used. The lamp socket may be a two-pin base unit, for example a G9.5 unit as supplied by Osram/Sylvania which is adapted to receive many kinds of lamp typically having a power output from 300-1000 watts, or may be selected according to the type and size of the lamp used and the application of the lamp reflector.

In addition, in any of the above-described embodiments, the lamp reflector can be parabolic, spherical, elliptical, planar or a combination thereof, and may be adapted to provide different beam angles, i.e. spot and flood range. The lamp reflector may be a standard PAR lamp reflector as used, for example, in stage lighting. Such lamp reflectors are available in four sizes,

these being 36, 46, 56 and 64 and can optionally have their inner reflecting surface dimpled (the PAR plus reflectors) or facetted to remove filament reflections ("hot spots"). Preferred reflectors are shown in Figures 27 and 28. Typically, reflectors are fabricated from super pure 99.99% aluminium or lower grade aluminium with a cladding of for example 15% by thickness of super pure aluminium to act as a reflecting surface. The reflecting surface may be brightened by the ALCAN "BRYTAL" proprietary process. The lamp reflector may further include optical coatings to reduce infra-red emissions. A front lens may also be used to provide a further means of varying the beam pattern and range. A clear lens can also be used to act as a lamp shield in the event of a lamp explosion. In this regard, it will be noted that the reflector shown in conjunction with the lamp fitting of the second-described embodiment is provided with clips for this purpose.

Applications of a lamp unit incorporating the fitting of the present invention include industrial, architectural, stage and night club lighting. In addition, by the provision of a weather-proof housing, such units can be used outdoors.

It will be understood by a person skilled in the art that various modifications and adaptations can be made to the embodiments described hereinabove without departing from the scope of the present invention as defined in the appended claims. In one such modification the lamp fittings may be adapted to provide radial adjustment of a lamp within a reflector, that is movement in the X and Y axis, in addition to movement in the axial direction, the Z axis. In this way, a lamp can be centred within a reflector. This XYZ axis control can be achieved by employing a linear axial detent track in the adjustment knob for axial positioning of the lamp by a simple push-pull action, and incorporating a further element having orthogonally arranged detent tracks

for permitting positioning of a lamp in the X and Y axis.