Abstract:
Described are an improved automated luminaire  12  and luminaire systems  10  employing an improved iris  40.  The iris  40  is improved by simultaneously improving the thermal conductivity of the system for wicking away heat and the use of a bearing race  41  within the iris structure  40.

Description:
RELATED APPLICATION(S) 
       [0001]    This application is a utility filing claiming priority of provisional application 61/165,289 filed on 31 Mar. 2010. 
     
    
     TECHNICAL FIELD OF THE INVENTION 
       [0002]    The present invention generally relates to an automated luminaire, specifically to an iris for use within an automated luminaire. 
       BACKGROUND OF THE INVENTION 
       [0003]    Luminaires with automated and remotely controllable functionality are well known in the entertainment and architectural lighting markets. Such products are commonly used in theatres, television studios, concerts, theme parks, night clubs and other venues. A typical product will commonly provide control over the pan and tilt functions of the luminaire allowing the operator to control the direction the luminaire is pointing and thus the position of the light beam on the stage or in the studio. Typically this position control is done via control of the luminaire&#39;s position in two orthogonal rotational axes usually referred to as pan and tilt. Many products provide control over other parameters such as the intensity, color, focus, beam size, beam shape and beam pattern. The beam pattern is often provided by a stencil or slide called a gobo which may be a steel, aluminum or etched glass pattern. The products manufactured by Robe Show Lighting such as the ColorSpot 700E are typical of the art. 
         [0004]    The optical systems of such luminaires may include a gate or aperture through which the light is constrained to pass. Mounted in or near this gate may be devices such as gobos, patterns, irises, color filters or other beam modifying devices as known in the art. The use of a variable aperture or iris diaphragm allows control over the size of the output beam and thus the size of the image projected onto a surface. When placed in the optical path within a luminaire removed from a focal point the iris may be used to serve the role of a variable dimmer either progressively decreasing or increasing the light intensity as the iris either closes or opens respectively. 
         [0005]      FIG. 1  illustrates a multiparameter automated luminaire system  10 . These systems commonly include a plurality of multiparameter automated luminaires  12  which typically each contain on-board a light source (not shown), light modulation devices, electric motors coupled to mechanical drives systems and control electronics (not shown). In addition to being connected to mains power either directly or through a power distribution system (not shown), each luminaire is connected is series or in parallel to data link  14  to one or more control desks  15 . The luminaire system  10  is typically controlled by an operator through the control desk  15 . 
         [0006]      FIG. 2  illustrates a prior art automated luminaire  12 . A lamp  21  contains a light source  22  which emits light. The light is reflected and controlled by reflector  20  through an aperture or imaging gate  24  and then through a variable aperture  23 . The resultant light beam may be further constrained, shaped, colored and filtered by optical devices  26  which may include dichroic color filters, gobos, rotating gobos, framing shutters, effects glass and other optical devices well known in the art. The final output beam may be transmitted through output lenses  28  and  29  which may form a zoom lens system. 
         [0007]    Variable aperture  23  is most commonly constructed as an iris diaphragm which contains a series of overlapping leaves that may be adjusted by a single lever or gear to control the effective size of the aperture. 
         [0008]      FIGS. 3 ,  4 ,  5 ,  6 ,  7  and  8  illustrate the construction and operation of a prior art example of an iris diaphragm  30 . Iris diaphragms are well known in the art and have been utilized as variable apertures in luminaires for many years. Iris diaphragms in automated luminaires typically employ multiple thin leaves  36  which are constrained on both sides to avoid problems caused by buckling of the thin leaves  36  due to the inherent high temperature operating conditions frequently found in an automated luminaire. 
         [0009]      FIGS. 3 ,  4 ,  5 ,  6 ,  7  and  8  illustrate such an iris diaphragm where both ends of the leaves  36  are constrained by housing  38  and stationary ring  34 . Handle  32  of actuator ring  37  to which one end of each of the leaves  36  are pivotally attached. The other end of leaves  36  have tabs  35  which ride in slots  39  in stationary ring  34  which is in turn fixed to stationary housing  38  constraining the movement of the leaves  36 . Leaves  36  are held within slots  39  of the stationary rung  34  by pressure applied to the underside of actuator ring  37  by stationary housing  38 . As the handle  32  is rotated in one direction, the leaves individually rotate about their pivoted ends they are constrained by tab  35  and slot  39  and occlude an increasing amount of the central aperture space. When the handle  32  moves in the opposite direction the leaves  36  occlude a decreasing amount of the central aperture space. 
         [0010]      FIG. 3  illustrates an iris diaphragm  30  in a position where actuator  32  is at one extreme of its motion and leaves  36  are fully thus maximizing the central aperture. 
         [0011]      FIG. 4  illustrates an iris diaphragm  30  in a position where actuator  32  is at its midpoint and leaves  36  have been rotated to their midpoint thus occluding a portion of the central aperture. Note that the resultant aperture formed by the juxtaposition of the leaves is not a true circle. The more leaves  36  that are used in the design the closer to circular the resultant aperture. Using more leaves  36  also tends to increase the friction in the system and the risk of problems in opening and closing of the iris particularly in high temperature conditions. 
         [0012]      FIG. 5  illustrates an iris diaphragm  30  in a position where actuator  32  is at the other extreme of its motion and leaves  36  are fully rotated thus occluding the majority of the central aperture. It can be seen that as previously discussed actuator ring  37  is in contact with the inside surface of fixed housing  38  and thus there is considerable friction between these two surfaces particularly in higher temperature or in varying temperature conditions. Prior art devices have made various attempts to minimize this friction by using lubricants or coatings on the mating surfaces of actuator ring  37  and stationary housing  38  however these coatings and lubricants frequently cause increased friction at the high operating temperatures of automated luminaires. Increased friction in the rotation of actuator ring  37  may result in jerky or steppy movement visible to the audience and, in extreme cases, may result in the iris diaphragm becoming so stiff to move that the small stepper motor frequently utilized to move actuator  32  is unable to overcome that friction and the iris becomes stuck. Such a system is also prone to increased problems due to accumulation of dust and dirt as the fixture ages and is maintained. Further problems may arise from the poor thermal transfer of heat from leaves  36  through actuator ring  37  to stationary housing  38 . 
         [0013]    There is a need for an improved iris diaphragm mechanism for automated luminaire which provides reduced and consistent friction between the operating components and improved thermal transfer to allow operation at a wide range of operating temperatures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings in which like reference numerals indicate like features and wherein: 
           [0015]      FIG. 1  illustrates a typical automated lighting system; 
           [0016]      FIG. 2  illustrates a typical automated luminaire; 
           [0017]      FIG. 3  illustrates a prior art iris diaphragm; 
           [0018]      FIG. 4  illustrates a prior art iris diaphragm; 
           [0019]      FIG. 5  illustrates a prior art iris diaphragm; 
           [0020]      FIG. 6  illustrates a prior art iris diaphragm; 
           [0021]      FIG. 7  illustrates a prior art iris diaphragm; 
           [0022]      FIG. 8  illustrates a prior art iris diaphragm; 
           [0023]      FIG. 9  illustrates an embodiment of the invention; 
           [0024]      FIG. 10  illustrates an embodiment of the invention; 
           [0025]      FIG. 11  illustrates an embodiment of the invention; 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    Preferred embodiments of the present invention are illustrated in the FIGUREs, like numerals being used to refer to like and corresponding parts of the various drawings. 
         [0027]    The present invention generally relates to an automated luminaire, specifically to the configuration of an iris diaphragm within such a luminaire such that the mechanism supporting movement of the iris diaphragm provides reduced and consistent friction between the operating components at a wide range of operating temperatures. 
         [0028]      FIG. 9  illustrates an exploded drawing of an embodiment of the invention. Iris diaphragm  40  comprises a set of leaves  46  that may be rotated to variably occlude a central aperture. 
         [0029]    The first, outer, ends (not shown) of leaves  46  are pivotally attached to stationary housing  48  such that leaves  46  may rotate across the central aperture. The second, inner, ends of leaves  46  have tabs  45  which ride in slots  49  in actuator ring  44 . Actuator ring  44  may be rotated by an external motor drive system (not shown); such motorized operation is well known in the art. The motor may be of a type selected from a list comprising but not limited to, stepper motors, servo motors, and linear actuators. As actuator ring  47  rotates it links the rotation through slots  49  to tabs  45  on leaves  46 . As leaves  46  individually rotate about their pivoted ends they are constrained by tab  45  and slot  49  to occlude an increasing amount of the central aperture. Leaves  46  are held within slots  49  of the actuator ring  44  by pressure applied to the underside of actuator ring  44  through ball bearing race  41  to stationary housing  48 . 
         [0030]    Bearing race  41  provides a first improvement over the prior art by providing a controlled low friction bearing surface through ball bearing race  41  between the actuator ring  44  and stationary housing  48 . Ball bearing race  41  provides smooth and consistent motion for the actuator ring  44 . 
         [0031]    A further improvement of the invention over the prior art is provided by fixing the stationary end of leaves  46  directly to the stationary housing  48  rather than through an intermediate ring (shown as  37  in  FIG. 6 ). This direct connection to stationary housing  48  provides an improved heat path with lower thermal resistance from leaves  46  to stationary housing  48  and thus to the chassis of the luminaire. This allows heat from the leaves heated by the light from the luminaire to pass readily from the leaves thus keeping them at a lower temperature and reducing distortion and warping due to excessive heat. 
         [0032]      FIGS. 10 and 11  illustrate an embodiment of the invention in its final assembled state. 
         [0033]    While the disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the disclosure as disclosed herein. The disclosure has been described in detail, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the disclosure. For Example, although the invention is described as holding the housing  48  stationary and rotating actuator ring  44  the invention is not so limited and this operation may be reversed by holding the actuator ring stationary and rotating the housing without departing from the spirit of the invention.