Patent Publication Number: US-2010118538-A1

Title: Adjustable light fixture with lens directed beam

Description:
CROSS REFERENCE TO RELATED APPLICATION(S) 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     REFERENCE TO A MICROFICHE APPENDIX 
     Not applicable. 
     TECHNICAL FIELD 
     The present invention is directed toward light fixtures, and particularly toward light fixtures providing highly controlled and directed lighting. 
     BACKGROUND OF THE INVENTION AND TECHNICAL PROBLEMS POSED BY THE PRIOR ART 
     Light fixtures are, of course, used in many applications throughoutthe world to fundamentally provide more light to areas than would naturally occur based not only on the time of day and position of the sun, but also in shaded and enclosed areas throughout the day. 
     Such lighting not only involves basic illumination but also often includes spotlighting different areas for a variety of reasons, including not only aesthetics but also to highlight specific features and/or areas. Particularly in those installations having a need for highly controlled and directed spotlighting, for example, lenses have been used to direct the light shining from the fixture. Such lenses can not only focus the light, but can also shape it so that, for example, it will form a square spotlight, an oval spotlight, or virtually any desired shape. For example, museum displays may be highlighted by spotlights to not only make such areas more clearly viewable but also to draw viewers&#39; attention to different areas in a particular manner by the shape of the light. Such lighting may also be used in theaters and with sales displays (e.g., in retail stores), as well as virtually any situation where such lighting is deemed to be desirable, including lighting in homes. 
     It should be appreciated, therefore, that particularly in installations where shaped spotlights are being used, it is important to be able to direct the light appropriately, which requires not only that the light fixture be appropriately oriented but also that the lens be appropriately oriented as well. U.S. Pat. No. 5,325,281 illustrates a light fixture which may have its direction adjusted through use of a pole (to facilitate making such adjustments when the fixture is located at a relatively inaccessible location such as a high ceiling). However, those light fixtures do not use lenses which require orientation beyond the direction in which the light beam is pointed. Such orientation with the required precision is often difficult if not impossible with many such fixtures, and U.S. Pat. No. 5,325,281 teaches nothing in that respect. 
     It should also be appreciated that the light source used in such fixtures will typically have to be changed with some degree of frequency. Additionally, it should be appreciated that since such fixtures can have a lens covering that light source, removal of the lens will be required in order to gain access to the area of the light source. However, while skilled personnel may be available to initially position the light fixture (e.g., in a new art museum display, a lighting technician may manipulate the fixture while working with an artist to choose the desired orientation of the spotlight), such personnel cannot reasonably be expected to be available to change the light source when necessary (e.g., when a light bulb burns out). More commonly, a regular custodian, who cannot be expected to be skilled in the art of lighting, will be expected to change light bulbs when they burn out. 
     Since the lens must typically be physically removed from the fixture in order to change the bulb, there is a serious risk that the lens will not be replaced appropriately after changing a bulb. For example, after the bulb is changed the fixture may be slightly moved to change the direction of the spotlight. Similarly, when lens is used to provide a non-circular shaped (e.g., elliptical, rectangular, square) spotlight which is oriented in a particular manner to provide a desired effect, there is a serious risk that the lens may be replaced in a different position so that the orientation of the shaped spotlight will no longer be as desired. A custodian typically cannot be reasonably expected to recognize whether the location and orientation of a spotlight remains as desired after replacing the bulb, nor can he be expected to be able to properly and precisely reorient the spotlight even if he were to recognize that the replaced bulb provides a spotlight which is not the same as previously provided. 
     The present invention is directed toward overcoming one or more of the problems set forth above. 
     SUMMARY OF THE INVENTION 
     In one aspect of the present invention, an adjustable lighting fixture for mounting on a support is provided, including a mounting arm and a light housing. The mounting arm extends axially from an end mountable on a support and is adjustably rotatable about the axis. The light housing includes a housing base mounted to the mounting arm for adjustable rotation about a second axis substantially orthogonal to the mounting arm axis, and a housing portion for housing a light source. The housing portion includes a light opening through which light from the light source may pass and a lens mounting adapted to selectively mount a lens in the light opening to direct light from the light source in a selected path, where the housing portion with a mounted lens substantially enclose the light source and the housing portion is removably securable in a fixed orientation relative to the housing base. 
     In one form of this aspect of the invention, the housing portion and housing base are removably securable together, with a first cylindrical lip around the housing base and a second cylindrical lip around the housing portion, where one of the cylindrical lips receivable in the other. Annular grooves in the two lips face one another and axially overlap when the housing portion is removably secured to the housing base. A key connection between the cylindrical lips ensures that they are securable together in only one angular orientation and a C-spring is received in the grooves. In a still further form, the C-spring is biased into one of the grooves when an axial force is applied between the housing portion and the housing base. 
     In another form of this aspect of the present invention, the housing portion and housing base are removably securable together by a key defining a selected orientation therebetween and a plurality of detent connections between the housing base and the housing portion. In a further form, the housing base includes a substantially flat base portion, the housing portion is defined by walls extending substantially perpendicular to the base portion and, when secured together, the base portion is positioned inside of the walls and the detent connections extend outwardly from the edge of the flat base portion toward the walls. In a still further form, the flat base portion edge is irregularly shaped whereby the housing portion may be secured thereto in only one orientation. 
     In still another form of this aspect of the present invention, which may be used with either of the above described forms, the lens mounting includes an inner thread inside the housing portion adapted to engage an outer thread of a lens, whereby the lens may be selectively threaded in the housing portion inner thread to selectively position the lens axially and angularly relative to the housing portion to direct light from the light source in a selected path, and a lock is provided to secure a lens in the selected threaded position relative to the housing portion. In a further form, a lip extends inwardly on the interior of the housing portion, a first cylindrical member has a radially projecting flange on one side and a portion extending axially from the flange with threaded portions on its inner and outer surfaces, a second cylindrical member has a threaded portion on its inner surface, whereby the second cylindrical member threaded portion is threaded onto the outer surface threaded portion of the first cylindrical member with the inwardly extending housing portion lip between the first cylindrical member flange and the second cylindrical member, wherein the inner surface threaded portion of the first cylindrical member is the housing portion inner thread. According to a still further form, the lock includes a first lock for securing the lens relative to the first cylindrical member, and a second lock for securing the second cylindrical member relative to the housing portion inwardly extending lip. 
     In yet another form of this aspect of the present invention, a drive shaft is rotatable about the orthogonal axis relative to the mounting arm, with the drive shaft fixed on one end to the housing portion for rotation therewith and having a gear fixed on its other end, and a worm extends axially in the mounting arm with the worm drivably engaging the drive shaft and having a drivable end exposed at the mounting arm other end. In a further form, the mounting arm and the light housing have mating cylindrical portions mounted together with the drive shaft having a diameter smaller than the cylindrical portion, and a power line extends through the cylindrical portions in the radial space between the drive shaft and the inner walls of the cylindrical portions. In a still further form, the light housing includes a cylindrical opening coaxial with the housing cylindrical portion, the cylindrical opening having a smaller diameter than the housing cylindrical portion, with an arcuate slot defined between the cylindrical opening and the housing, and the power line extending through the arcuate slot into the housing. 
     According to another form of this aspect of the present invention, the support is a power supplying track, and a U-shaped mounting member with legs is adapted to fit over the track, wherein the end of the legs are securable to the mounting arm first end. In a further form, the mounting member legs and the mounting arm track end include interengageable threaded portions. 
     According to still another form of this aspect of the present invention, the support is a power supplying track, and an insulated power line extends inside the fixture from the mounting arm first end where it is adapted to engage one side of a power circuit on the track to an insulated base in the light housing, wherein the light housing and mounting arm connect the insulated base to the other side of the power circuit on the track. 
     According to yet another form of this aspect of the present invention, the mounting arm and the light housing have mating cylindrical portions mounted together, and scale indicators on the cylindrical portions indicate the rotated position of the drive shaft around the orthogonal axis. 
     In another aspect of the present invention, an adjustable lighting fixture for mounting on a support is provided, including a mounting arm, a light housing and a drive. The mounting arm extends axially from an end mountable on a support and is adjustably rotatable about the axis. The light housing includes a housing base mounted to the mounting arm for adjustable rotation about a second axis substantially orthogonal to the mounting arm axis, and a housing portion for housing a light source. The housing portion includes a light opening through which light from the light source may pass and a lens mounting adapted to selectively mount a lens in the light opening to direct light from the light source in a selected path. The lens mounting includes an inner thread inside the housing portion adapted to engage an outer thread of a lens, whereby the lens may be selectively threaded in the housing portion inner thread to selectively position the lens axially and angularly relative to the housing portion to direct light from the light source in a selected path, and a lock for securing a lens in the selected threaded position relative to the housing portion. The housing portion and a mounted lens substantially enclose the light source, and the housing portion is removably securable in a fixed orientation relative to the housing base. The drive adjustably rotates the housing base about the second axis, and includes a drive shaft rotatable about the second axis relative to the mounting arm with the drive shaft fixed on one end to the housing portion for rotation therewith and having a gear fixed on its other end, and also includes a worm extending axially in the mounting arm, the worm drivably engaging the drive shaft and having a drivable end exposed at the mounting arm second end. 
     In one form of this aspect of the invention, the housing portion and housing base are removably securable together, with a first cylindrical lip around the housing base and a second cylindrical lip around the housing portion, where one of the cylindrical lips receivable in the other. Annular grooves in the two lips face one another and axially overlap when the housing portion is removably secured to the housing base. A key connection between the cylindrical lips ensures that they are securable together in only one angular orientation and a C-spring is received in the grooves. In a still further form, the C-spring is biased into one of the grooves when an axial force is applied between the housing portion and the housing base. 
     In another form of this aspect of the present invention, the housing portion and housing base are removably securable together by a key defining a selected orientation therebetween and a plurality of detent connections between the housing base and the housing portion. In a further form, the housing base includes a substantially flat base portion, the housing portion is defined by walls extending substantially perpendicular to the base portion and, when secured together, the base portion is positioned inside of the walls and the detent connections extend outwardly from the edge of the flat base portion toward the walls. In a still further form, the flat base portion edge is irregularly shaped whereby the housing portion may be secured thereto in only one orientation. 
     In still another form of this aspect of the present invention, which may be used with either of the above described forms, a lip extends inwardly on the interior of the housing portion, a first cylindrical member has a radially projecting flange on one side and a portion extending axially from the flange with threaded portions on its inner and outer surfaces, a second cylindrical member has a threaded portion on its inner surface, whereby the second cylindrical member threaded portion is threaded onto the outer surface threaded portion of the first cylindrical member with the inwardly extending housing portion lip between the first cylindrical member flange and the second cylindrical member, wherein the inner surface threaded portion of the first cylindrical member is the housing portion inner thread. According to a still further form, the lock includes a first lock for securing the lens relative to the first cylindrical member, and a second lock for securing the second cylindrical member relative to the housing portion inwardly extending lip. 
     According to still another form of this aspect of the present invention, the support is a power supplying track, and an insulated power line extends inside the fixture from the mounting arm first end where it is adapted to engage one side of a power circuit on the track to an insulated base in the light housing, wherein the light housing and mounting arm connect the insulated base to the other side of the power circuit on the track. 
     According to yet another form of this aspect of the present invention, the mounting arm and the light housing have mating cylindrical portions mounted together, and scale indicators on the cylindrical portions indicate the rotated position of the drive shaft around the orthogonal axis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a light fixture according to a first embodiment of the present invention as mounted on a track; 
         FIG. 2  is a perspective view of a light fixture according to a second embodiment of the present invention; 
         FIG. 3  is a partially exploded view of the light fixture of  FIG. 1  illustrating the structure for adjusting the position of the fixture; 
         FIG. 4  is a partial cross-sectional view of the light fixture of  FIG. 2 ; 
         FIG. 5  is a partial cross-sectional view of the light fixture of  FIG. 1 ; 
         FIGS. 6 and 7  are perspective partially broken away views of a portion of the light fixtures of the present invention; 
         FIGS. 8 and 9  are perspective views of the mounting arm of a light fixture according to the present invention as variously mounted to a track; 
         FIG. 10  is a perspective partially broken view illustrating a connection of the light fixture to a track; 
         FIG. 11  is a partial cross-sectional view of a third light fixture embodying aspects of the present invention, with a cylindrical shaped housing; 
         FIG. 12  is a partial cross-sectional view of the  FIG. 11  fixture, with the housing and lens mount exploded; 
         FIG. 13  is a top, partially cut-away view of the square light fixture of  FIG. 2  illustrating the connection of the light housing portion to the light housing base; 
         FIG. 14  is a partial cross-sectional view of a fourth light fixture embodying aspects of the present invention, with a spherical shaped housing, with  FIG. 14   a  showing enlarged detail of the C-spring connection; 
         FIG. 15  is a partial cross-sectional view of the  FIG. 14  fixture, with the housing base, C-spring and housing portion exploded, with  FIG. 15   a  showing enlarged detail of the area connected in  FIG. 14   a;  and 
         FIG. 16  is an exploded perspective view of the connection of the housing base and removable housing portion with a C-spring. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A first light fixture  20  according to the present invention is shown in  FIG. 1  as mounted on a track  22 . It should be appreciated that while mounting of the fixture  20  on a track  22  can be advantageous, many of the aspects of the present invention may also be obtained no matter what the support on which the fixture is mounted. 
     The fixture  20  includes an adjustable mount  24  with a generally axial mounting arm  26  for a light housing  28 . The mounting arm  26  may be adjustably rotated about its axis  30  as further described below, and the light housing  28  may be adjustably rotated about an axis  32  normal or orthogonal to the arm axis  30  as also further described below. It should be appreciated, therefore, that the light housing  28  may be selectively pointed in virtually any direction so as to generally direct light from a light source inside the housing  28  in a desired direction, as also described in greater detail hereafter. 
     A U-shaped mounting member  40  includes downwardly depending legs  42  which are adapted to fit over the track  22  and to be suitably secured to the top of the mounting arm  26 , as described hereafter, to secure the fixture  20  to the track  22  for sliding therealong to place the light fixture  20  in the desired position on the track  22 . It should be appreciated, however, that still other structures for securing the mounting arm  26  to a track  22  may be advantageously used within the scope of at least some aspects of the present invention. It should further be appreciated that light fixtures embodying aspects of the present invention may also be used with lighting systems other than track lighting. 
       FIG. 2  illustrates a second light fixture  20 ′ wherein components identical to those in  FIG. 1  are given the same reference numeral. This fixture  20 ′ has a similar adjustable mount  24  permitting adjustable rotation about axes  30 ,  32  which are generally orthogonal to each other. 
       FIG. 3  illustrates an exploded view of one adjustable mount  24  which may be used with the present invention. 
     The mount  24  includes an outer connector body  44  with an inner thread  46  which may be removably secured to the mounting member  40  by screwing the threaded bottom portion of the mounting member legs  42  into the inner thread  46  of the outer connector body  44 . 
     An inner connector body  50  is rotatably received inside the outer connector body  44 , and suitably secured thereto by suitable securement (for example, a threaded connection) to the upper end of the shaft  52  of a connector adapter  54  which extends through a reduced diameter portion (not shown) in the bottom of the outer connector body  44 . 
     A suitable connector  60  for one side of the light power circuit is also provided in the top of the mounting arm  24 , and includes a bottom stem  62  which may be received inside a threaded nylon isolator  64  which itself is received inside the inner connector body  50 . The exposed end  70  of an insulated wire  72  (not shown in  FIG. 3 , but shown in  FIGS. 6-7 ) is suitably secured in the isolator  64  in conductive contact with the connector stem  62 . The insulated wire  72  extends up through a central passageway through the various components of the mounting arm  24  whereby the wire  72  defining that side of the power circuit is advantageously retained inside the fixture  20 , extending from the connector  60  to the inside of the light housing  28  as described in more detail hereafter. 
     The outer metallic conductive components of the fixture may define the other side of the power circuit when used with low voltage light systems, such as 12 volt track lighting. However, it should be understood that light fixtures according to the present invention may be used with different track structures and different associated connectors. Further, at least some aspects of the present invention may also be obtained when used with supporting/power supplying structures other than tracks. 
     A set screw  76  extending through the outer connector body  44  may be tightened to engage the outer surface of the inner connector body  50  to secure them together in a selected rotational position about the generally vertical axis  30  (see  FIGS. 8-9 ). 
     A gear body housing  80  is suitably secured to the mounting arm  24 , as by engagement of an inner thread  82  with an outer thread on the head of the connector adapter  54 . 
     A worm  90  is secured in the gear body housing  80 , beneath a worm gear lock  92  also threaded inside the worm gear housing  80 , and a worm gear washer  94 . The bottom of the worm  90  includes a suitable irregular recess which may be accessed through an opening  96  in the gear body housing  80  (see  FIG. 7 ) for engagement by a suitable tool (e.g., with an Allen wrench type attachment) to rotate the worm  90 . 
     A gear  100  is also suitably secured in the gear body housing  80  (e.g., by a screw  102  through the side of the gear body housing  80  and longitudinally in the gear  100 ) so as to be rotatable around the orthogonal axis  32 . The gear  100  is drivably engaged with the worm  90  (see  FIG. 6 ) whereby rotation of the worm  90  will cause the gear  100  to rotate about its axis  32 . 
     The distal end of the gear shaft  104  is suitably fixed to a light housing base  110  which includes a cylindrical portion  112  which suitably mates with a cylindrical opening  114  in the gear body housing  80 . A suitable scale  116  (e.g., angular marks) may be provided at the connection to indicate the relative rotational positions. This may be used not only to record the proper desired orientation of a particular fixture  20 , but may also be used to facilitate related orientation of multiple fixtures  20  in settings where, for example, it is desired to have multiple fixtures oriented in the same direction. 
     It should be appreciated that the fixture  80  thus provides a pathway through the mounting arm  24 , the gear body housing  80 , and the housing base cylindrical portion  112  into the housing base  110  for the insulated wire  72 , to both protect the wire  72  and for aesthetic purposes as illustrated in  FIGS. 6-7 . For example, the distal end of the gear shaft  104  may be suitably secured (e.g., by a set screw) in a central opening  120  of a mounting plate  122  suitably secured at the inner end of the base cylindrical portion  112 . An arcuate slot  130  through the mounting plate  122  and around its central opening  120  allows passage of the wire  72  into the housing base  110  where the wire end may be secured to an insulated socket structure  134  (e.g., by screws  136 ). The socket structure  134  is adapted to secure a suitable light source (e.g., light bulb  140 ), with the power circuit running from one side of the track  22 , through the wire  72 , then through the light bulb  140  to generate the desired light, then through the metal housing components of the fixture  20  to the other side of the track  22 . 
     A two prong MR  16  lamp is illustrated as one type of bulb which would be suitable for this fixture  20 . However, it should be appreciated that still other bulbs/lamps could be used within the scope of the present invention, with suitable sockets or other attachments provided in the housing base  110  to accommodate such bulbs. 
     Advantageously according to the present invention, the light housing  28  includes a housing base  110  which is securely connected to the mounting arm  24  for rotation about the orthogonal axis  32 . The housing base  110  also may include another housing section  144  fixed thereto, as by screws  146 . 
     The light housing  28  also includes a housing portion  150  which is adapted to securely and precisely mount a spread lens  160  (see  FIGS. 4 ,  5 ,  11  and  12 ) over the lamp  140  as described in greater detail below. The spread lens  160  may advantageously be adapted to direct light from the lamp  140  into a beam having a selected shape (e.g., such as an oval or a square beam). Thus, the fixture  20  may be used in museum settings, etc. such as described herein, where unique and precisely selected lighting may be provided for areas and displayed objects. It should be appreciated that positioning the fixture  20  in selected positions around the axes  30 ,  32  will allow the beam to generally be directed in precisely the desired direction. 
     Moreover, in accordance with the present invention, the housing portion  150  may not only be precisely mounted so as to also precisely mount the lens  160  to further direct and shape the beam as desired, but that housing portion  150  may be readily removed from the housing base  110  as required to change a light bulb  140  in the housing  28  and then replaced after the bulb  140  is changed so as to be returned in the precisely required position previously established. 
       FIGS. 4 ,  5 ,  11  and  12  illustrate the advantageous mounting of the lens  160 . Specifically, referring first to  FIGS. 11 and 12  (which relate to a third fixture  20 ″ having a cylindrical shaped housing  28 ), the interior of the housing portion  150 ″ includes a lip  164  extending inwardly. A first cylindrical member  168  includes a radially projecting flange  170  and an axially extending portion  172  with an inner thread  174  and an outer thread  176  on at least its upper end. A second cylindrical member  180  has an inner thread  182  which may be threaded over the first cylindrical member outer thread  176  to secure the two over the housing portion lip  164 . 
     The lens  160  is adjustably located in the first cylindrical member  168  so that it may be both axially and rotationally adjusted. Specifically, the lens  160  may advantageously be supported in a threaded mount  186  which may be positioned by screwing it into the inner thread  174  of the first cylindrical member  168 . The threaded mount  186  may be advantageously frictionally retained in position, or suitable locks for securing the lens  160  therein may be used (e.g., set screws) or spacers  188  may also be provided. Similarly, locks such as set screws  189  may be used to secure the cylindrical members  168 ,  180  in place. Further, recesses  190  may be provided in the cylindrical members  168 ,  180  and threaded mount  186  to allow use of suitable spanner wrenches or the like to screw the components together. 
     Referring now to  FIG. 4 , a similar light mounting may be provided with a square housing  28 ′. In this alternate embodiment, the upper cylindrical member  180 ′ may receive the lower cylindrical member  168  in a downwardly open annular groove  200 , with the groove  200  having a radially outwardly facing thread which may be engaged with the inner thread  174  of the first cylindrical member  168 ′ (thereby negating the need for an outer thread on the first cylindrical member  168 ′. Though the outer housing  28 ′ is square, an inner cylindrical lip  164 ′ is provided to facilitate locating and adjusting the lens  160  therein.  FIG. 5  illustrates still another variation of a light mounting, wherein the upper (second) cylindrical member  180 ′ includes an inwardly extending flange with an inner thread, thereby extending the axial distance through which the lens  160  may be mounted. Of course, it should be appreciated that still other lens mount variations could be provided within this aspect of the present invention. 
       FIG. 10  illustrates one suitable connection of the fixture mounting arm  24  to the track  22 . Specifically, the connector  60  projects up above the upper lip of the outer connector body  44  so that it engages the bottom track member  210  with the mounting member  40  pressed against the upper track member  212  when screwed tightly into the outer connector body  44 . An insulated separator  216  is between the track members  210 ,  212 . Thus, it should be appreciated that the wire side of the power circuit is connected to the bottom track member  210  via the connector  60 , whereas the other side of the power circuit (through the outer housing of the fixture  20 ) engages the upper track member  212  via the mounting member  40  with the other side of the power circuit maintained spaced from the lower track member by the insulated separator  216 . Of course, as previously mentioned, the present invention could be used with different tracks, different mounts for securing to the track, or even different base mounts which are not used with tracks at all. 
       FIG. 13  illustrates one structure for removably securing the square light housing portion  28 ′ from the housing base  110 ′. Specifically, the top surface  230  of the light housing portion  28 ′ includes an irregularly shaped opening  232  (e.g., including one recess  234  in an otherwise circular opening, with the recess  234  defining a key) which may be aligned in only one orientation with the similarly irregularly shaped outwardly projecting flange  236  of the housing base  110 ′. Spherical detents  240  are biased outwardly from the outer surface of the base outwardly projecting flange  236  so as to extend into an inwardly open annular groove  242  below the top surface  230  of the housing portion  28 ′. 
     It should thus be appreciated that when a light bulb  140  burns out in the light fixture  20 ′ having the structure illustrated in  FIGS. 2 ,  4  and  13 , a custodian may simply grasp the square housing  28 ′ and pull it down and off of the housing base  110 ′ (as the detents  240  will be pushed in clear of the housing upper surface  230  when the housing  28 ′ is pulled down). The custodian may then easily gain access to the light bulb  140  to remove it, and to replace it with a new bulb  140 , after which he can return the square housing  28 ′ by aligning its irregularly shaped opening  232  with the irregularly shaped flange  236  of the housing base  110 ′ and simply snap it back into place (with the detents  240  again in the annular groove  242  of the housing portion  28 ′). 
     Particularly, it should be noted that when a bulb is changed, even though the lens was necessarily removed in order to be able to gain access to the bulb, the lens  160  is reliably replaced in the same position as it was when the light was first position by a lighting technician (working, possibly, in conjunction with an artist). Therefore, the fixture  20 ′ will provide the same shaped beam as previously set without the less skilled custodian having to worry about resetting the lens and/or fixture to some particular desired orientation which may not even be known by the custodian. 
       FIGS. 14 and 15  illustrate yet another structure for removably securing a portion of the light housing  28 ″ from the housing base  110 ″. Specifically, in this structure, the housing  28 ″ is generally spherical with a portion  300  of the spherical housing  28 ″ being a fixed part of the housing base  110 ″ and a removable housing portion  310 . The removable housing portion  310  includes an inner cylindrical lip  164 ″ for mounting of the lens  160  as previously described, though the lens  160  and its mounting structure are omitted from  FIGS. 14 and 15  for clarity. 
     As illustrated in the exploded view of  FIGS. 15 and 15   a,  the removable housing portion  310  includes a cylindrical lip  314  and the housing base portion  300  includes a cylindrical lip  318  within which the removably housing portion lip  310  may be received. A C-spring  320  is receivable in facing grooves  324 ,  328  in each of the lips  314 ,  318  whereby when snapped together the housing base portion  300  and the removable housing portion  310  will be retained together by the interference overlapping of C-spring  320  with the top of groove  324  and the bottom of groove  328  as seen in  FIG. 14   a.    
     A key connection  340  (see  FIG. 16 ) ensures proper rotational alignment of the removable housing portion  310  with the housing base portion  300 . Specifically, the key  340  consists of a slot  344  in the inner lip  314  and an inwardly projecting key  348  on the outer lip  318 , with the key  348  ensuring that the removable housing portion  310  can only be aligned in a single angular orientation (with its slot  344  aligned with the key  348 ). Thus, as with the  FIG. 13  connection, when a bulb is changed and the lens is necessarily removed in order to be able to gain access to the bulb, the lens  160  is reliably replaced in the same position as it was when the light was first positioned. Therefore, the fixture  20 ′ will provide the same shaped beam as previously set without the less skilled custodian having to worry about resetting the lens and/or fixture to some particular desired orientation which may not even be known by the custodian. 
     As also seen in  FIG. 16 , it should be appreciated that the gap in the C-spring  320  should be slightly greater than the width of the key  348 , and that the inner diameter of the groove  324  plus twice the diameter of the body of the C-spring  320  (i.e., the diameter of the material of the C-spring  320 ) be no greater than the inner diameter of bottom of the lip  318  of the housing base portion  300 . Similarly, the depth of the groove  324  should advantageously be about the diameter of the body of the C-spring  320 . As a result, the housing potion  310  and housing base portion  300  may be removed by pulling them apart, whereby the pulling force will cause the C-spring  320  to squeeze together into the groove  324  so that it may clear the bottom portion of the lip  318  of the housing base portion  300 . The housing base portion  300  and removable housing portion  310  can similarly be snapped back together by pushing them together, with that force also causing the C-spring  320  to squeeze together into the groove  324  so that it may clear the bottom portion of the lip  318  of the housing base portion  300 . 
     Suitable tapers  350 ,  352  (see  FIG. 15   a ) may also be provided around the bottom inner edge of the lip  318  which cams with the round C-spring  320  to facilitate squeezing together of the C-spring  320  when the removable housing portion  310  and housing base portion  300  are pushed together or pulled apart (with the C-spring  320  in the groove  324  of the removable housing portion lip  314 ). 
     Still other aspects, objects, and advantages of the present invention can be obtained from a study of the specification, the drawings, and the appended claims. It should be understood, however, that the present invention could be used in alternate forms where less than all of the objects and advantages of the present invention and preferred embodiment as described above would be obtained.