Abstract:
An apparatus and method for keeping a high intensity discharge arc tube relatively horizontal in a light fixture regardless of aiming orientation of the light fixture towards a target. In one aspect, the light source is mounted in an independently pivotal yoke in the light fixture. A gearing arrangement automatically proportionally pivots the light source relative to any pivoting motion of the fixture over a range of motion such that a selected light source orientation can be approximately maintained regardless of aiming orientation of the fixture.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation application of U.S. Ser. No. 11/332,938 filed Jan. 17, 2006, which claims priority under 35 U.S.C. § 119 of a provisional application U. S. Serial No. 60/644,536 filed Jan. 18, 2005, all of which are incorporated by reference in their entirety. This application is also a non-provisional of the following provisional U.S. applications, all filed Jan. 18, 2005: U. S. Serial No. 60/644,639; U.S. Serial No. 60/644,747; U.S. Serial No. 60/644,534; U.S. Serial No. 60/644,720; U.S. Serial No. 60/644,688; U.S. Serial No. 60/644,636; U.S. Serial No. 60/644,517; U.S. Serial No. 60/644,609; U.S. Serial No. 60/644,516; U.S. Serial No. 60/644,546; U.S. Serial No. 60/644,547; U.S. Serial No. 60/644,638; U.S. Serial No. 60/644,537; U.S. Serial No. 60/644,637; U.S. Serial No. 60/644,719; U.S. Serial No. 60/644,784; U.S. Serial No. 60/644,687, each of which is herein incorporated by reference in its entirety. 
       INCORPORATION BY REFERENCE 
       [0002]    The contents of the following U. S. Patents are incorporated by reference by their entirety: Nos. 4,816,974; 4,947,303; 5,161,883; 5,600,537; 5,816,691; 5,856,721; 6,036,338. 
     
    
     BACKGROUND OF THE INVENTION 
       [0003]    A. Field of the Invention 
         [0004]      FIGS. 1A-F  generally illustrate a sports field lighting system (see also the patents incorporated by reference). There is room for improvement with such fixtures and how they are operated. 
         [0005]    B. Problems in the Art 
         [0006]    The problem of light loss from tilt factor in certain HID lamps is well known. The present applicant has created and patented several ways to operate an arc tube in a glass envelope in generally horizontal position. See certain of above-cited patents which are incorporated by reference herein. 
         [0007]    There is still room for improvement in this area. Some solutions require structure that must be manually adjusted after the fixture is elevated. This is subject to error and is labor intensive. Some solutions fix the relationship of the arc tube relative the fixture. However, in most sports lighting systems the fixtures vary in angular orientation to the ground. In these cases, it is not possible to insure that all arc tubes for the system end up installed in a horizontal position. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention relates to an apparatus and method for automatically keeping the arc tube of an HID lamp in a pre-determined orientation relative the fixture. It comprises a mechanism that maintains the arc tube in the same general orientation to the reflector of a light fixture regardless if the orientation of the reflector relative to the fixture is changed. 
         [0009]    In one aspect a gearing arrangement between a yoke holding the lamp, a mounting elbow for the fixture, and the reflector, a new way of looking at sports lighting. The invention pertains to apparatus, methods, and systems to effectively and more energy-efficiently deliver light to the target space, and reduce glare and spill light outside the target space. 
         [0010]    It is therefore a principal object, feature, or advantage of the present invention to present a high intensity lighting fixture, its method of use, and its incorporation into a lighting system, which improves over or solves certain problems and deficiencies in the art. 
         [0011]    An apparatus according to one aspect of the invention comprises a high intensity lighting fixture apparatus with a yoke is adapted to hold the arc lamp so that its arc tube operates in a horizontal position, or as close as possible thereto, over most conventional operating positions for the fixture. 
         [0012]    In another aspect of the invention, an arc lamp with an arc tube offset from the longitudinal axis of the lamp envelope is used in combination with the yoke. The arc tube offset can be at an aiming angle within the typical range of aiming angles for sports lighting. The yoke and associated structure would keep the arc tube at or about horizontal automatically even though the reflector is moved anywhere in that typical range. 
         [0013]    These and other objects, features, advantages and aspects of the present invention will become more apparent with reference to the accompanying specification and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0014]      FIGS. 1A-F  illustrate general components of a sports lighting system. 
           [0015]      FIGS. 2A-C  illustrate a high intensity discharge arc lamp that is used with an exemplary embodiment of the present invention. 
           [0016]      FIG. 3  is a diagrammatic, partial exploded view of a light fixture  10  according to an exemplary embodiment of the present invention. 
           [0017]      FIGS. 4A-C  is a diagrammatic illustration of operation of an automatic tilt factor correction mechanism according to an exemplary embodiment of the invention. 
           [0018]      FIGS. 5A-J  are various views of a bulb cone into which an HID lamp can be removably mounted and to which a reflector can be mounted. 
           [0019]      FIGS. 6A-H  are various views of an elbow mount for connection to a cross arm on a pole. 
           [0020]      FIGS. 7A-K  are various views of an elbow connectable to the elbow mount of  FIG. 6A  and to the cone of  FIG. 5A . 
           [0021]      FIGS. 8A-D  are various views of a gearing piece useful with the preferred embodiment. 
           [0022]      FIGS. 9A-D  are various views of a bushing used with a bolt to pivotably connect the elbow and cone. 
           [0023]      FIGS. 10A-B  show a spring used with the preferred embodiment. 
           [0024]      FIGS. 11  A-B show a strap member used to lock the cone to the elbow. 
           [0025]      FIGS. 12A-F  show additional straps used for such locking. 
           [0026]      FIGS. 13A-F  show an end stop also used for adjustable locking of the angular orientation of the cone to the elbow. 
           [0027]      FIGS. 14A-J  are various views of a yoke into which the HID lamp is mounted which can pivot angularly relative to the cone. 
           [0028]      FIGS. 15A-D  are views of yoke retainers. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0029]    A. Exemplary Apparatus
       1. Lighting Fixture  10  Generally       
 
         [0031]      FIG. 3  shows the basic components of sports lighting fixture  10  in exploded form. 
         [0032]    Lamp cone  40  (360 Aluminum with polyester powder coat) pivots around axis  52  relative to knuckle  50 . It contains a socket  154  (shown diagrammatically in  FIG. 14A , commercially available) which is bolted to the flat web  160  between the arms  156  and  158  of yoke  80  (see  FIG. 14A ). Lamp  20  (Musco Corporation Z-Lamp™) has a threaded base that can be screwed in and out of socket  154  (shown screwed into operating position in  FIG. 3 ) to install or remove lamp  20 .
       2. Lamp  20         
 
         [0034]    Arc lamp  20  is of the general type disclosed in Musco Corporation U.S. Pat. No. 5,856,721, incorporated by reference herein, with certain modifications. These types of lamps are used by Musco Corporation under the trademark Z-Lamp™ and typically are 1000 watt or greater metal halide (MH) HID lamps. Its arc tube  12  is tilted obliquely across the longitudinal axis of the arc lamp  20 . In operation, it is rotationally positioned in fixture  10  such that the longitudinal axes of the arc tube and the lamp define a vertical plane, and the longitudinal axis of arc tube  12  is as close to a horizontal plane as possible.
       3. Yoke  80         
 
         [0036]    Yoke  80  is pivotally supported at the front of lamp cone  40  at pivot axis  140  (see  FIGS. 3 and 5C ). Pivot pins  152  of lamp yoke  80  (see FIG.  14 A—and described in more detail below) slide longitudinally into mating receivers  134  (which define pivot axis  140 ) on opposite sides of opening  132  to lamp cone  40  and are retained in place by yoke retainers  173  ( FIGS. 15A-D ) by machine screws in the pair of threaded bores on opposite sides of receivers  134 . 
         [0037]    Lamp socket  154  is mounted between arms  156  and  158  of yoke  80  via bolts, screws or other means through the back end  160  of yoke  80 . Yoke  80  therefore can pivot around an axis  140  defined by receivers  134  in lamp cone  40 . In combination with a setting of gearing, pivotable yoke  80  allows arc tube  12  of arc lamp  20 , which is supported by yoke  80 , to be maintained in a horizontal position independent of tilt of lamp cone  40 .  FIGS. 4A-E , along with  FIGS. 5A and 14A , illustrate this total tilt factor correction feature of fixture  10 . 
         [0038]    Pinion gear  202  ( FIGS. 8A-D ) has a large gear portion  204  spaced parallel from a small gear portion  206  by shaft  208 . Shaft  208  is rotatably journaled in opening  138  in the side of lamp cone  40  (offset from the rotational axis of lamp cone  40  relative to knuckle  50 ). A bushing  203  (plastic sleeve/bushing— FIGS. 9A-E ), provides a bearing surface for shaft  208  of gear  202  in opening  138  of lamp cone  40 . 
         [0039]    When fixture  10  is assembled, small gear  206  engages gear rack  170  (see  FIG. 7A ) formed in knuckle  50 . Large gear  204 , in turn, engages gear rack  190  fixed on one side of yoke  80  (see  FIG. 14A ). Lamp cone  40  can rotate in a vertical plane around its pivot axis  136  relative to knuckle  50  to allow for different aiming angles for fixture  10  relative the target. Because the front of yoke  80  (at its pivot axis  140 ) is fixed relative to lamp cone  40 , yoke  80  also rotates in a vertical plane when lamp cone  40  does. If yoke  80  were completely fixed relative to lamp cone  40 , the longitudinal axis of lamp  20  would also rotate in a vertical plane. However, this would conflict with the preference to operate arc tube  12  in a horizontal plane regardless of aiming angle of the fixture. 
         [0040]    Thus, fixture  10  compensates for this as follows. Gear rack  170  is fixed on knuckle  50 . Knuckle  50  is fixed relative to cross arm  7 . The gearing and the parts involved with it are selected so that pivotal movement of lamp cone  40  around axis  140  causes a proportional pivoting of yoke  80  around its different pivot axis  136 . Placement of yoke pivot axis  140  is intentionally chosen to be at or near the front plane of lamp cone  40 . When lamp cone  40  is rotated upward, the front of yoke  80  and pinion gear  202  raise with it, but large gear  206 , at the same, lifts the back free end of yoke  80  a proportional amount so that the orientation of lamp  20  and its arc tube  12  remains the same relative to horizontal. 
         [0041]    When assembled, the longitudinal axis of yoke  80  is aligned or parallel with the longitudinal axis of lamp cone  40 . Thus, when lamp  20  is appropriately mounted on yoke  80 , its longitudinal axis would be oblique by the same angle to the longitudinal axes of lamp  20 , yoke  80  and lamp cone  40 . This is basically a reference position. If lamp cone  40 , for example, were tilted 30° down from horizontal relative to cross arm  7  when pole  5  is erected, yoke  80  would also have its longitudinal axis tilted down 30° from horizontal. This would put arc tube  12  in a horizontal plane. 
         [0042]    This relationship allows a lamp such as Z-lamp  20  ( FIGS. 3A-C ) to be utilized and operated at a horizontal position, so long as the angular offset of the arc tube relative to the longitudinal axes of the arc lamp is equal to the amount of tilt of lamp cone  40  from horizontal. Thus, if arc tube  12  is tilted 30° to the longitudinal axis of lamp  20 , and lamp  20  is rotated into the socket of yoke  80  such that the arc tube axes and lamp axes are in a vertical plane, arc tube  12  will be horizontal when lamp cone  40  is tilted 30° down from horizontal. As previously described, operation of arc tube  12  at horizontal will correct tilt factor. 
         [0043]    However, because not all fixtures will be aimed at 30° down from horizontal, yoke  80  automatically adjusts to maintain the orientation of yoke  80  relative to horizontal for a selected range (e.g. 15° up to 47° down in steps in the plane of knuckle  50 ) of pivoting of lamp cone on either side of the reference position (e.g., 30° down). 
         [0044]    This automatic tilt factor correction is further illustrated at  FIGS. 4A-F . If lamp cone  40  is tilted up several degrees from its 30° reference position relative to horizontal, pinion gear  202  will rotate in opening  138  of lamp cone  40  in a counter-clockwise direction as viewed in  FIG. 4D . Gear track  170  is fixed with respect to knuckle  50 , and with respect to space. The tilting of lamp cone  40  is about its rotational axis  136  (see  FIGS. 4A-F ), which is also stationary in space. The front of lamp cone  40 , and thus the front of yoke  80 , will move upward in an arc (see reference number 302,  FIGS. 4A-F ). Pinion gear  202  likewise will move upward in an arc (ref. no. 304). However, the counter-clockwise rotation of pinion gear  202  means large gear  204  will concurrently rotate counter-clockwise. Because large gear  204  is fixed relative to lamp cone  40 , the counter-clockwise rotation of large gear  204  will cause gear rack  190  to move in an a still third arc (ref. no. 306) inside lamp cone  40  vertically upward separately from the vertical upward movement of lamp cone  40 . Thus, the back of yoke  80  will pivot upwardly along with gear track  190  an amount proportional to the amount lamp cone  40  is pivoted upwardly because gear rack  190  is fixed to yoke  80 . A similar proportional downward movement of the back of yoke  80  will be automatic when lamp cone  40  is pivoted downward. However, the amount of movement of the back of yoke  80  is less then the amount of movement of lamp cone  40  because the back of yoke  80  is closer to the pivot axis of lamp cone  40 . 
         [0045]    In this embodiment, the range of tilt up and below horizontal (the arc tube reference position) is approximately +15 to −60°. This covers most conventional sports lighting aiming angles (95% of them at 30° beam and reference axes). It is noted that the guiding factor for operation of the automatic tilt factor correction is the pivot location of yoke  80 . It works as described because it is basically in the same plane as the junction between lamp cone  40  and reflector frame  30 . It would be more difficult to get precise correction if the yoke was pivoted to lamp cone  40  nearer the back of lamp cone  40 . While some change between the position of arc lamp  12  and the reflecting surfaces of fixture  10  occurs, it is relatively small. Thus minor re-aiming, if any is needed. 
         [0046]    The gear ratios (large and small gears  104  and  206  have the same number of teeth) are carefully selected such that there will be precise compensation for any upward or downward tilting of lamp cone  40  to maintain the same downward angular orientation of yoke  80 . In other words, despite yoke  80  being attached to, and moving with lamp cone  40  when it is pivoted away from its reference position, the gearing causes yoke  80  to pivot to maintain the same orientation relative to horizontal. Because lamp cone  40  pivots about a different axis than yoke  80 , selection of the gearing is critical to cause the right proportional movement of yoke  80 . Although the actual physical position of yoke  80  relative to lamp cone  40  will change somewhat, the orientation of yoke  80  stays parallel to its reference position. This will allow arc tube  12  of Z-lamp  20  to stay horizontal regardless of whether lamp cone  40  is in the reference position or some degree off of the reference position (within the range of the gearing). 
         [0047]    To provide against play and to inject a biasing force relative to yoke  80 , an extension spring  210  (see  FIGS. 10A-B ), attaches between post  212  of yoke  80  and post  214  at the front of lamp cone  40 . The spring is selected to maintain a suitable biasing force. It essentially pre-loads the gearing so there is not play in the gears or backlash. This increases the accuracy of the aiming. When maintenance on lamp  10  is performed, spring  120  can be easily disengaged by pulling it off of post  214 . The pitch diameter of the last few teeth on large gear  204  are cut off slightly greater than the pitch diameter of the other teeth. This makes that combination less sensitive to reengagement. 
         [0048]      FIGS. 11 ,  12 , and  13  show what is called straps and an end stop that can be clamped along the curved slot in knuckle  50 . A projection from the side of cone  40  extends into that curved slot when cone  40  is pivotally connected to knuckle  50  by bolt  174 . The angular orientation of cone  40  relative knuckle  50  can therefore be set by where strap pair  146 ,  148  is clamped in position (as a lower end stop), and where end stop  142  is positioned and clamped in place (as an upper end stop). This combination provides more holding power to withstand torque forces than just relying on the tightening of bolt  174 . The straps and end stop can have structure that allow them to be clamped in place along the curved channel by tightening of bolts. Additionally, it allows for relatively easy release of the position for cone  40 . Two bolts on the straps for the bottom end stop can simply be released and that end strap pair slid away. This would allow, for example, a maintenance crew to go up and work on a fixture. The lower end stop straps could be released and the fixture tilted down to hang vertically while they worked on it. By leaving the upper end stop clamped into position, when finished, the workers just pivot the lamp and cone  40  back until into abutment with the upper end stop, slide the lower end stop strap pair into abutment with the projection or boss from the end cone that is in the slot, and retighten the screws. The original aiming of the fixture is therefore retained. It avoids having to do any re-aiming or calibrations. 
         [0049]    As discussed above, one feature of the invention is maintaining an orientation of the lamp relative to some reference position substantially independent of the pivoting of the cone  40 . As can be appreciated, the exemplary embodiment does this with the multiple pivot axes and gearing. This arrangement, however, while maintaining its substantially consistent orientation of the lamp with some external reference plane does cause slight movement of the lamp relative to the reflector that is attached to cone  40 . This can slightly alter the beam pattern from the fixture. For example, if cone  40  is tilted upwardly approximately 15° from a 30° down position, not only would the reflector connected to the cone tilt up 15°, the repositioning of the lamp inside the reflector would cause a beam shift an additional approximately 7½ more degrees up. Being aware of this, and compensating for this, is sometimes required. However, because of fairly known proportionalities once a configuration is selected, this can be built into the design of the system. It actually can be advantageous in that even though there might be some physical limit of how far up or down cone  40  can be adjusted (for example because of physical limitations in the structure of the fixture or for that matter, practical limitations), the beam shift created by that adjustment is proportionally more, thus giving a wider range of potential adjustments. 
         [0050]    Further discussion of benefits of the total tilt factor correction structure and options for it can be found in the patents incorporated by reference herein. 
         [0051]    It will be appreciated that the foregoing exemplary embodiment is given by way of example only and not by way of limitation. Variations obvious to those skilled in the art will be included in the invention. The scope of the invention is defined solely by the claims. 
         [0052]    Utilization of the Musco Z-Lamp is not necessarily required. By appropriate modification, a standard arc lamp could be utilized. 
         [0053]    It will be appreciated that the combination of components shown in the figures is but one way in which adjustability between a mount for the fixture to a cross arm, and the fixture can be accomplished. The figures illustrate how, in the exemplary embodiment, an integration of the gearing and the adjustable yoke allows for compensation and maintenance of an orientation of the arc lamp regardless of orientation vertically of the cone in which the yoke is contained (over a reasonable range). The drawings are intended to show to one skilled in the art one combination. The general concept is to have some compensation or mechanism for the function and result of maintaining a certain orientation of the lamp.