Abstract:
A light pipe fixture with adjustable beam spreads comprises a bayonet assembly having a generally tubular coupling for receiving a light-dispensing end of a light pipe, and a receiver assembly. The receiver assembly has a generally tubular coupling for receiving therewithin the bayonet assembly coupling at adjustable levels of penetration of the bayonet assembly coupling within the receiver assembly coupling. The receiver assembly further comprises an optical lens and a hollow portion for focusing a light beam from the end of the light pipe through the lens. The radial interior surface of the receiver assembly coupling and the radial exterior surface of the bayonet assembly coupling may be configured so the receiver assembly coupling slidably and lockingly receives the bayonet assembly coupling in any of a plurality of positions along the length of the receiver assembly coupling.

Description:
[0001]    This application claims priority from U.S. Provisional Application No. 60/452,806 filed on Mar. 7, 2003. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to fixtures for a light pipe with various features for conveniently installing the fixtures in a ceiling, for instance.  
         BACKGROUND OF THE INVENTION  
         [0003]    In the general- and accent-lighting applications, customers often require flexibility in the angular distribution of the light. This flexibility is sometimes related to the lighting being used in a space that has changing requirements. An example is a retail space where different products are displayed in different ways each week. In this retail space example, spot lights may be desirable for small items, and wider beam flood lights might be appropriate for larger items.  
           [0004]    Another common situation is where a lighting designer or architect will place light points within a space before the final furniture or decoration design is set. The furniture and decoration become targets for the lighting to illuminate once they are set in place, and they may require specific light beam spreads to achieve desirable lighting.  
           [0005]    The lighting consumer has several options to install adjustable light today. For very large fixtures used in factories or warehouses, there are often one or two settings for a socket within a large reflector. By moving the socket, a customer can change the beam spread to a few different settings, but this is rarely done because of the difficulty involved. Instead, the fixtures are usually set in the factory and never changed.  
           [0006]    A second option available today is to use lamps with integral reflectors that have different beam spreads. One example of this is low voltage halogen lamps, of which MR-16 is a common type. The MR-16 lamps are available in several light beam spreads from very narrow spot lights (with angular extents of about 7 degrees) to very wide flood lights (with angular extents of about 60 degrees). The most common beam spreads for the accent-lighting applications where MR-16s are used are 15, 25 and 40 degrees. This strategy causes complications when lamps are changed after burning out. All MR-16s are very similar in appearance, and beam patterns within a space are only maintained after re-lamping if the exact same lamp is used to replace the burned out lamp. This strategy also requires many different lamp types to be kept on hand.  
           [0007]    Fiber optic lighting has historically offered an easier option for adjusting beam spread. Because fiber optic lighting delivers lighting in a forward direction of usually less than about one steradian, it can easily be controlled with imaging or non imaging lenses. By moving the fiber output face with relation to the beam forming lens, different beam spreads can be achieved. Fiber optic lighting fixtures exist today which allow infinite adjustment of the distance from the lens to the fiber. Sometimes these fixtures will have visual guides to help the installer guide the beam setting to the desired angular setting. Because there is infinite adjustment, and only a visual guide to beam setting, in any field of fixtures that are desired to be at the same beam angle, significant variation will be observed. So, the beam-angle accuracy is limited to the skill of the installer. Further, these types of infinite-adjustable systems often rely on compression on the fiber with a set screw or compression fitting to hold the fiber in place. When the angular distribution of the light is changed frequently, these mechanical stresses on the fiber will cause damage leading to further beam inconsistency and light loss.  
           [0008]    It would thus be desirable to provide a light pipe fixture that allows easy adjustment of beam spreads of the light, even after the fixture has been installed.  
           [0009]    It would further be desirable to provide a light pipe fixture in which mechanical stresses imposed on the light pipe supplying light to the fixture is minimized.  
         SUMMARY OF THE INVENTION  
         [0010]    The invention provides, in a preferred form, a light pipe fixture with adjustable beam spreads. The fixture comprises a bayonet assembly having a generally tubular coupling for receiving a light-dispensing end of a light pipe, and a receiver assembly. The receiver assembly has a generally tubular coupling for receiving therewithin the bayonet assembly coupling at adjustable levels of penetration of the bayonet assembly coupling within the receiver assembly coupling. The receiver assembly further comprises an optical lens and a hollow portion for focusing a light beam from the end of the light pipe through the lens.  
           [0011]    Preferably, the radial interior surface of the receiver assembly coupling and the radial exterior surface of the bayonet assembly coupling are so configured that the receiver assembly coupling slidably and lockingly receives the bayonet assembly coupling in any of a plurality of positions along the length of the receiver assembly coupling, so as to allow for different discrete distances between the end of the fiber and the lens.  
           [0012]    The foregoing structures provide a light pipe fixture that allows easy adjustment of beam spreads of the light, even after the fixture has been installed. Other advantages and features of the invention will become apparent from the following specification. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0013]    In the drawings, like reference numerals refer to like parts.  
         [0014]    [0014]FIG. 1 is an isometric, exploded view of a bayonet assembly, light pipe, receiver assembly and lens in accordance with the invention.  
         [0015]    [0015]FIG. 2 a  is a side view of the bayonet assembly and light pipe of FIG. 1; FIG. 2 b  is a sectional view of FIG. 2 a  taken at Arrows  2   b - 2   b  in FIG. 2 a ; and FIG. 2 c  is an enlargement of the circled portion of FIG. 2 b  labeled FIG. 2 c.    
         [0016]    [0016]FIG. 3 a  is a side view of the receiver assembly of FIG. 1; FIG. 3 b  is a sectional view of FIG. 3 a  taken at Arrows  3   b - 3   b  in FIG. 3 a ; and FIG. 3 c  is an enlargement of the circled portion of FIG. 3 b  labeled FIG. 3 c.    
         [0017]    [0017]FIGS. 4 a - 4   c  are isometric views, partially cutaway, of initial relative positions of the bayonet and receiver assemblies of FIG. 1 for attaining different light beam spreads.  
         [0018]    [0018]FIG. 5 is an isometric view of the bayonet assembly of FIG. 1.  
         [0019]    [0019]FIG. 6 a  is a sectional, isometric view of the receiver assembly of FIG. 1; and FIG. 6 b  is an enlargement of the circled portion in FIG. 6 a  labeled FIG. 6 b.    
         [0020]    [0020]FIG. 7 a  is an isometric view of a bayonet assembly and a receiver assembly, with the receiver assembly shown without the surface on which positioning pads and circumferential flange stops are mounted, for simplicity of illustration; and FIG. 7 b  is an enlargement of the circled portion in FIG. 7 a  labeled FIG. 7 b.    
         [0021]    [0021]FIGS. 8 a - 8   c  show isometric views of a bayonet assembly and receiver assembly in various stages of interconnection for selecting a 15-degree light beam spread, with outer portions of the bayonet assembly removed or broken away to show more clearly positioning pads and attached circumferential flange stops of the receiver assembly; and FIG. 8 d  is an enlargement of the circled portion in FIG. 8 c  labeled FIG. 8 d.    
         [0022]    [0022]FIG. 8 e  is an isometric view of a portion of the bayonet and receiver assemblies of FIG. 1, partially in cross section, with an outer portion of the bayonet assembly removed to show more clearly a radial-bearing region; and FIG. 8 f  is an enlargement of the circled portion in FIG. 8 e  labeled FIG. 8 f , shown partially broken away.  
         [0023]    [0023]FIG. 8 g  is an isometric view of the bayonet and receiver assemblies of FIG. 1. The figure shows the receiver assembly partially in cross section and with an outer portion removed in the vicinity of the bayonet assembly to portray more clearly a radial-bearing section of the receiver assembly.  
         [0024]    [0024]FIG. 9 a  is an upper isometric view, partially cutaway, of a fixed-angle ceiling mount installation using the bayonet and receiver assemblies of FIG. 1; and FIG. 9 b  is a simplified enlargement of the circled portion in FIG. 9 a  labeled FIG. 9 b.    
         [0025]    [0025]FIGS. 10 a - 10   c  show parts of the structure of FIG. 9 a  as viewed at Arrows  10   a - 10   a  in FIG. 9 a  and are partially in cross section, the different figures showing different heights of the bayonet assembly relative to a sled.  
         [0026]    [0026]FIG. 11 is an upper isometric view, partially cutaway, of an adjustable-angle ceiling mounting fixture using the bayonet and receiver assemblies of FIG. 1.  
         [0027]    [0027]FIG. 12 a  is an isometric view of the bayonet and receiver assemblies of FIG. 1, including a beauty ring as also shown in FIG. 11; and FIG. 12 b  is an enlargement of the circled portion of FIG. 12 a  labeled FIG. 12 b.    
         [0028]    [0028]FIGS. 12 c  and  12   d  are like FIGS. 12 a  and  12   b , respectively, but show the beauty ring further away from the receiver assembly.  
         [0029]    [0029]FIG. 13 a  is an exploded, isometric view of the bayonet and receiver assembly of FIG. 1, showing a different beauty ring that may be accommodated.  
         [0030]    [0030]FIG. 13 b  is a side plan view of the arrangement of FIG. 13 a ; and FIG. 13 c  is an enlargement of the circled portion of FIG. 13 b  labeled FIG. 13 c.    
         [0031]    [0031]FIG. 13 d  is a side plan view of the arrangement of FIG. 13 a ; and FIG. 13 e  is an enlargement of the circled portion of FIG. 13 d  labeled FIG. 13 e.   
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0032]    This description covers three features relating to (1) bayonet and receiver assemblies, (2) a fixed-angle ceiling mount installation, and (3) an adjustable-angle ceiling mount installation.  
       1. Bayonet and Receiver Assemblies  
       [0033]    [0033]FIG. 1 shows a bayonet assembly  10  and cooperating receiver assembly  12 , which holds a lens  14 . These three components are essential parts of the light pipe fixture of the invention. By way of example, lens  14  may be a plano-convex lens, an aspherical lens, a holographic lens, a Fresnel lens or a flat lens, made from either glass or plastic.  
         [0034]    Light pipe  16  is received into bayonet assembly  16  and secured in such assembly by an adhesive. As shown in connection with FIGS. 2 a - 2   c , bayonet assembly  12  uses an internal lip  18  (FIG. 2 c ) to stop the inserted light pipe at a precise location.  
         [0035]    As shown in connection with FIGS. 3 a - 3   b , receiver assembly  12  utilizes an internal shelf  20  (FIG. 3 c ) and radial snaps  22  (FIG. 3 c ) to lock the lens into a precise location. With receiver assembly  12  being molded from Acrylonitrile Butadiene Styrene (ABS), for instance, radial snaps  22 , preferably two in number, preferably occupy between about 5 and 20 degrees of circumference about a longitudinal axis  24  of such assembly, and more preferably between about 5 and 15 degrees. Preferably, the ABS for the receiver assembly is “platable” in that it can accept such coatings as chrome or brass, for reflective purposes.  
         [0036]    [0036]FIGS. 4 a - 4   c  show respective, initial relative positions of bayonet assembly  10  and receiver assembly  12  for achieving light beam spreads exiting lens  14  of degrees of 15, 25 and 40, respectively, by way of example. In the positions shown, a notch  28  or other mark on receiver assembly  12  is aligned with markings on the bayonet assembly  10  for a desired degree of beam spread; for instance, FIG. 4 a  showing notch  28  aligned with “15” for a 15-degree beam spread. Each of the various beam spread adjustment locations is clearly marked on bayonet.  
         [0037]    In more detail, a user inserts bayonet assembly  10  into receiver assembly  12  as shown in any of FIGS. 4 a - 4   c  until the bayonet assembly reaches a full stop within receiver assembly  10 . The user then rotates the bayonet assembly relative to the receiver assembly in the direction of an arrow  30  until a full rotational stop is reached, at which point the bayonet assembly becomes locked to the receiver assembly. For the embodiment shown, the rotation of bayonet assembly  10  relative to receiver assembly  12  is {fraction (1/12)} th  turn, or 30 degrees.  
         [0038]    The foregoing lock-in adjustment location ability of the bayonet &amp; receiver assembly arrangement is made possible by appropriate contouring of the confronting surfaces of the bayonet assembly  10  and receiver assembly  12 . With reference to FIG. 5, bayonet assembly  10  uses an axial stop ledge  32  and circumferential lock flange  34  that extend radially outwards from a substantially cylindrical surface  36 , which is a surface that radially bears against cooperating surfaces of receiver assembly  12 . Axial stop ledge  32  is axially aligned with lock flange  32 . The additional geometric structures on the bayonet assembly (e.g.,  37 ) allow for clearance for different beam-spread positions and may also block contaminants, as described below.  
         [0039]    At this point, it should be noted that the described radially outwardly facing surface of bayonet assembly  10  forms a pattern from about 180 degrees about a longitudinal axis  38  of the assembly, which pattern repeats for the other approximately 180 degrees about such longitudinal axis. This same approximately 180-degree repeating of patterns applies also to receiver assembly  12 .  
         [0040]    Now, referring to receiver assembly  12  of FIGS. 6 a  and  6   b , receiving channels  40 , circumferential flange stops  42  and axial positioning pads  44  are shown extending radially inwardly from a generally cylindrical surface  46 . Flange stops  42  and positioning pads  44  are mounted on a radial bearing region  45 , which extends towards axis  38  from surface  46 . Radial bearing surface  45  supports radial bearing loads when the bayonet assembly is inserted into the receiver assembly, and structurally supports positioning pads  44 . Another function of radial bearing surface  45  will be described below.  
         [0041]    During insertion of bayonet assembly  10  (FIG. 5) into receiver assembly  12  (FIG. 6 a ), circumferential lock flange  34  (FIG. 5) is guided into a receiving channel  44  (FIG. 6 a ), such as vertically middle-shown channel  44 , until axial stop ledge  32  (FIG. 5) abuts the vertically lowermost-shown positioning pad  44  (FIG. 6 a ). At this point, bayonet assembly  10  is then turned 30° clockwise relative to receiver assembly  12  so that circumferential lock flange  34  (FIG. 5) passes a cam lock point (or projection)  48  (FIG. 6 b ) to lock the circumferential lock flange against a circumferential flange stop. In this position (not shown), a positioning pad  44  (FIG. 6 a ) is sandwiched in the axial space between circumferential stop flange  34  and axial stop ledge  32 . This operation can be more easily understood with reference to FIGS. 7 a - 7   b  and  8   a - 8   c.    
         [0042]    As in FIG. 5, FIG. 7 a  shows bayonet assembly  10  with axial stop ledge  32 , circumferential flange lock  34  and additional structure  37 . As in FIG. 6 a , FIG. 7 a  also shows receiver assembly  12  with circumferential flange stops  42  and axial positioning pads  44 . However, FIG. 7 a  has been simplified by omitting the mounting surface for these stops  42  and pads  44 , as is shown at  44  in FIG. 6 a ; and FIG. 7 b  shows these structures as six stops  42   a - 42   f  and six pads  44   a - 44   f . For practicality, it is preferred that the number of stops and pads be four, six (as shown) or eight.  
         [0043]    With the foregoing structure in mind, the selection of a 15-degree beam spread is shown in FIGS. 8 a - 8   c . FIG. 8 a  shows the insertion of circumferential lock flange  34  into the receiving channel  40  between axial positioning pads  44   a  and  44   b . FIG. 8 b  shows the final extent of insertion of lock flange  34 , when axial stop ledge  32  abuts axial positioning pad  44   a . Then, bayonet assembly  10  is then rotated 30 degrees clockwise relative to receiver assembly  12 , as shown in FIG. 8 c , at which point axial positioning pad  44   b  is sandwiched between axial stop ledge  32  and circumferential lock flange  34 . At this point, also, axial stop ledge  32  stops rotating since it then abuts circumferential flange stop  42   a . At this point, finally, as shown in the detail view of FIG. 8 d , lock flange  34  has rotated past a cam lock projection  54  on positioning pad  44   b , which locks in the bayonet assembly relative to the receiver assembly at the 15-degree beam spread position.  
         [0044]    [0044]FIG. 8 e  shows bayonet assembly  10  and receiver assembly  12 . This figure shows assembly  23  partially in cross section and with an outer portion removed to show more clearly radial-bearing region  45 , described above in connection with FIG. 6 a . The enlarged view of FIG. 8 f  shows radial-bearing region  45  of receiver assembly  12  supporting positioning pads  44   a  and  44   b . It further shows circumferential lock flange  34  of bayonet assembly  12  extending axially past positioning pad  44   b , and circumferentially positioned so that it has started to pass under positioning pad  44   b . Surface  32   a  of axial stop ledge  32  of the bayonet assembly axially abuts positioning pad  44   b , similar to the position shown in FIG. 8 b . Part of surface  32   a , shown broken away, also abuts a portion of an annular shelf  55  of radial-bearing region  45 . Upon rotating bayonet assembly  12  clockwise in relation to receiver assembly (such rotation not shown in FIG. 8 f ), when viewing from right to left in FIG. 8 f , surface  32   a  of stop ledge  32  continues to abut, and be supported by, annular shelf  55 . Preferably, annular shelf  55  of radial-bearing region  45  forms a continuous annular surface with positioning pad  44   b , which continuous annular surface fully supports the entire surface  32   a  of ledge  32 . This provides a stable coupling between the bayonet and receiver assemblies, and help assure that the locking action described above in connection with FIG. 6 b  will reliably occur.  
         [0045]    In the embodiment illustrated herein, annular shelves such as that shown in FIG. 8 f  at  55  are associated with positioning pads  44   b  and  44   c  (FIG. 7 b ), but not with positioning pad  44   a.    
         [0046]    The above-described bayonet assembly  10  and receiver assembly  12  were designed as molded components, with bayonet assembly  10  of polycarbonate plastic and receiver assembly of platable ABS, as mentioned above. This provides low cost and an easily reproducible product.  
         [0047]    In addition, in the one of the three beam-spread positions in which the bayonet assembly is inserted the furthest into the receiver assembly, the present design blocks contaminants from reaching the light pipe. In particular, such interstices are configured to block any direct path for contaminants to reach the light-dispensing end of the light pipe when the bayonet assembly is locked in position with the receiver assembly. This is shown in FIG. 8 g , wherein structure  37  of bayonet assembly cooperates with radial-bearing region  45  of the receiver assembly to block a direct path for contaminants to reach the light pipe when the bayonet and receiver assemblies are locked together. Thus, although not sealed, the foregoing design is considered closed, since it does not allow allows a direct path for dust, spray, or insects to reach the light pipe end.  
         [0048]    Many earlier designs were abandoned because the components were not easily moldable.  
         [0049]    The receiver assembly, in particular, was the most difficult to design for molding as a component that was closed to contaminants as described above. The small bore size of the receiver assembly&#39;s area for receiving the bayonet assembly—typically about 20 mm—made any common undercut (or snap pocket) impossible to mold. Although the use of exterior inserted slide cores in a mold would have made the bayonet and receiver assemblies easy to make and effective, the receiver assembly&#39;s bore size needed to be kept small to keep the costs of the components and associated tooling reasonable and practical, as well to allow for mounting practical component sizes.  
         [0050]    The illustrated design of the bayonet and receiver assemblies allows for the successful molding of these components, as well as maintaining the small bore size and closure of any direct path for contaminants to reach the light pipe end.  
       2. Fixed-Angle Ceiling-Mount Installation  
       [0051]    The light pipe fixture described above, including bayonet assembly and receiving assembly, is the base unit to a fixed-angle ceiling mount installation shown in FIG. 9 a.    
         [0052]    [0052]FIG. 9 a  shows a compression fitting  60  for holding bayonet assembly  10  to a sled  62  that is mounted on a pair of rails  64  and  65 , which may be conventional Part No. 512HD sold by Erico International Corporation of Solon, Ohio. These rails have clamps  64   a  and  65   a  for attaching to the a standard “T” bar grid (e.g.,  66   a ,  66   b ) for supporting ceiling tiles  67  and  70 , for instance. Rails  64  and  65 , in turn, are mounted above a ceiling tile  67 , which may be a conventional ceiling tile used in office buildings. Light pipe  16  is supplied from a protective feeder pipe  68 , mounted on a bracket  69 , which in turn is mounted above another ceiling tile. In the foregoing arrangement, compression fitting  60  compresses against bayonet assembly  10 , rather than against light pipe  16  as is traditional. Beneficially, this prevents kinking of light pipe  16  with resulting light output loss and damage upon installation  
         [0053]    [0053]FIG. 9 b  shows details of compression fitting  60  and associated structure, including bayonet assembly  10 , receiver assembly  12  and light pipe  16 . Compression fitting has a cylindrical shank  60   a  with threads above a fixed nut  60   b  on which a threaded compression nut  60   c  is received, and threads below fixed nut  60   b  for receiving a nut  60   d . As is conventional, the upper portion  60   e  of shank  60   a  is not threaded, but rather has vertically extending slots (not shown). The vertical slots form a generally cylindrical structure that is compressed against the upper portion of bayonet assembly  10  to fix compression fitting  60  in relation to the bayonet assembly. Nut  60   d  then torques an annular portion of sled  62  against fixed nut  60   b , so as to fix compression fitting  60  in relation to sled  62 .  
         [0054]    Referring to FIG. 9 a , bayonet assembly  10  holds receiver assembly  12  in place, due to their mutual lock-in arrangement described above. With the mounting arrangement of FIG. 9 a , the angle of receiver assembly  12  and its lens remains fixed relative to the associated ceiling tile  67 .  
         [0055]    The height of bayonet assembly  10  can be adjusted vertically along the longitudinal axis of compression fitting  60 . This is important to be able to accommodate ceiling tiles of different thicknesses, as shown in FIGS. 10 a - 10   c . These figures, which use the same reference numerals as in FIG. 9 a , show three different height adjustments of bayonet assembly  10 , for accommodating ceiling tiles  67   a ,  67   b  and  67   c  of different thicknesses; for instance, thickness  84   a  (FIG. 10 a ) of 0.5 inch,  84   b  (FIG. 10 b ) of 1 inch, and  84   c  (FIG. 10 c ) 1.5 inch. In FIG. 10 c , sled  62  is inverted from its position in FIGS. 10 a  and  10   b.    
         [0056]    Referring to FIG. 9 a , sled  62  is shown mounted on rails  64  and  65 . The sled can attach to other mounting means such as a so-called Butterfly Mount. Such Butterfly Mount is sold, for instance, by RSA Lighting LLC of Chatsworth, Calif., as part light fixture assembly Part No. CO111STR. Other mounting means will be apparent to those of ordinary skill in the art based on the present specification. Such other mounting means may allow sled  62  to slide to different positions or to otherwise be mounted in different position, or may only allow mounting in a fixed position.  
       3. Adjustable-Angle Ceiling-Mount Installation  
       [0057]    In some light-fixture installations, it may be desirable to have the ability to repeatedly adjust the angle of the light. Thus, FIG. 11 shows a flexible gooseneck  90 , which, once bent, retains its position. The flexible portion of gooseneck  90 , numbered  90   a , may comprise helically wound metal (not shown) as is conventional, and the ends  90   b  and  90   c  of the gooseneck may include cylindrical sleeves. Sleeve  90   b  mounts about bayonet assembly  10  and is held with adhesive. Gooseneck  90  may be a conventional Part No. 96070 sold by Moffatt Products, Inc. Inc. of Watertown, S. Dak.  
         [0058]    Compression fitting  61 , which is typically larger than compression fitting  60  of FIG. 9 a , compresses against flexible portion  90   a  of gooseneck  90 , rather than against light pipe  16  as is traditional. Beneficially, this prevents kinking of light pipe  16  and resulting light output loss and damage upon installation.  
         [0059]    By using the gooseneck  90  and compression fitting  61  of FIG. 11 instead of compression fitting  60  of FIG. 9 c , the angle of direction of receiver assembly  12  can be easily, and repeatedly, manipulated as desired.  
         [0060]    As will be shown in the further drawing figures, the receiver assembly described herein may be designed to accommodate various beauty rings and an optional filter (not shown). Optional filters may comprise a beam-filtering lens, a coloring lens or a diffusing lens, by way of example.  
         [0061]    Thus, FIG. 12 a  shows a beauty ring  120  affixed to receiver assembly  12  tightly; that is, without clearance required for a typical optional filter of about 4 mm thickness. Ring  120  has a pair of similar, axially extending first and second latches  130   a  and  130   b  (behind assembly  12 ). As shown best in FIG. 12 b , the lower end of receiver assembly  12  has similar first and second recesses  136   a  and  136   b  (behind assembly  12 ) for receiving first and second latches  130   a  and  130   b . As shown in FIG. 12 b , recess  136   a  has a central path  137   a  extending axially, and first and second paths  137   b  and  137   c  extending in opposite circumferential directions from the central path at respectively different axial positions. The entranceways to first and second paths  137   b  and  137   c  have respective cam lock ramps  138  and  139 , for locking beauty ring  120  onto receiver assembly  12 .  
         [0062]    As shown in FIGS. 12 a  and  12   b , with latch  130   a  received in path  137   c , beauty ring  120  fits close to receiver assembly  12 . In such position, there is insufficient space between ring and assembly for a optical filter that typically is about 4 mm thick. In contrast, as shown in FIGS. 12 c  and  12   d , with latch  130  received in path  137   b , sufficient clearance  142  between ring and assembly exists for receiving an optical filter (not shown) of typically 4 mm thickness. However, as shown in FIGS. 12 a  and  12   b , without clearance for a typical 4 mm filter, the beauty ring can be easily mounted to the receiver assembly, and light output is maximized since more light can pass through the beauty ring that when clearance is provided for an optical filter.  
         [0063]    [0063]FIG. 13 a  shows bayonet assembly  10 , receiver assembly  12  and lens  14 , and a beauty ring  150  that can be used instead of ring  120  shown in FIGS. 12 a - 12   d . Ring  150  includes a pair of axially extending mounting arms  152   a  and  152   b  (shown behind beauty ring  150 ). Receiver assembly  12  includes a pair of mounting apertures  154   a  and  154   b  for respectively receiving the mounting arms  152   a  and  152   b.    
         [0064]    As better seen in FIGS. 13 b  and  13   c , in which there is insufficient clearance for a typical approx. 4 mm optical filter, mounting arm  152   a  includes a pair of axially spaced mounting valleys  156   a  and  156   b  that face radially and preferably radially outwards from a longitudinal axis of receiver assembly  12 . Correspondingly, mounting aperture  154   a  includes a mounting ridge  157  for selectively being received in one or the other of mounting valley  156   a  or  156   b . In FIGS. 13 b  and  13   c , mounting ridge  157  is received in mounting valley  156   a , leaving insufficient space to accommodate an optional 4 mm thick filter. As such, however, the beauty ring can be easily mounted to the receiver assembly, and light output is maximized since more light can pass through the beauty ring that when clearance is provided for an optical filter.  
         [0065]    [0065]FIGS. 13 d  and  13   e  correspond to FIGS. 13 b  and  13   c  except that, as shown in FIG. 13 e , upper mounting valley  156   b  receives mounting ridge  157   a . This provides a clearance  150  for a typical optical filter of about 4 mm thickness.  
         [0066]    The receiver assembly of FIG. 1 beneficially incorporates both the structures shown in FIGS. 12 a - 12   d  and in FIGS. 13 a - 13   e  so improve its versatility and thus reduce the need to stock different receiver assemblies for using the different beauty rings.  
         [0067]    While the invention has been described with respect to specific embodiments by way of illustration, many modifications and changes will occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true scope and spirit of the invention.