Abstract:
The described systems  200  provides a simplified slide system for longitudinal movement of optical light modulators  102  for automated luminaires  12  employing expansion and contractions slots  125, 126  which allow for precise smooth movement over a range of temperatures.

Description:
RELATED APPLICATION(S) 
       [0001]    This application is a utility filing claiming priority of provisional application 61/165,274 filed on 31 Mar. 2010. 
     
    
     TECHNICAL FIELD OF THE INVENTION 
       [0002]    The present invention generally relates to an automated luminaire, specifically to the configuration and control of the movement of lenses within such a 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 typically 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]      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 . 
         [0005]      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 . The resultant light beam may be further constrained, shaped, colored and filtered by optical devices  26  which may include dichroic color filters, goboes, rotating goboes, irises, 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. Lenses  28  and  29  may individually and separately be constrained to move along the optical axis on slide rails  30  and  32  so as to change the separation of lenses  28  and  29  and the relative position of the lenses to aperture  24  and optical device(s  26 . The movement of the lenses may change the effective focal length of the combination and therefore the image focus and image magnification. By adjusting the positions of the lenses the user can select a desired image size and then control the sharpness or focus of that image. The friction or dampening on the movement of lenses  28  and  29  and their interaction with slide rails  30  and  32  is critical to the smooth and accurate operation of the luminaire  12 . If the friction is too high then the lenses  28  and  29  may jam or stick on the rail(s)  30  or  32  and movement may be jerky. Additionally excess friction will cause hysteresis problems where a lens  28 ,  29  will be positioned differently when moving to a preset position in one direction  27  or  31  than when it moves to that same position from the opposite direction  31  or  27  respectively. Such jerky movement and hysteresis will be manifested as poor image quality in the projected beam or noticeable and distracting jumps in the focus and size of the projected image/beam. It is also important that the friction is not too low as that may cause overshoot or wobbling of the lenses  28 ,  29  as they move. As with many mechanical systems a critical amount of friction or dampening is key to smooth, controlled movement. 
         [0006]      FIG. 3  illustrates a prior art mechanism used to control the movement of a lens assembly  100  along the optical axis of an automated luminaire. Lens  102  is rigidly attached to a lens carrier  104 . Lens carrier  104  rides on a rail  112  such that lens carrier  104  may slide along cylindrical rail  112  and the lens  102  may be positioned as desired along the optical axis through connection  114  with belt  116 . Belt  114  is moved by the rotation of driven pulley  108  and runs on idler  110 . In the prior art embodiment illustrated there is a transverse circular hole (not shown in  FIG. 3 ) through lens carrier  120  of as diameter slightly larger than that of the rail  112  so that the carrier moves freely on the rail with the hole acting as a friction beating. It is important that movement is constrained to the optical axis only as any movement transverse to the optical axis will degrade the resultant image. Thus lens carrier  120  is typically long along the optical axis so as to minimize any possible rotation about axes that are orthogonal to the optical axis of lens carrier  120  on slide  112  and ensure that the lens is maintained perpendicular to the optical axis. A disadvantage of this system is that the long contact length between the lens carrier  120  and slide  112  produces excess friction between the two and the movement of the carrier along the slide may be stiff and jerky and also exhibit excess hysteresis. The use of lubricants is problematic as an oily or greasy surface will attract dust and other contaminants which may jam the movement. A further problem is that any deviation in the straightness of rail  112  may cause a jamming of the movement of carrier  120 . 
         [0007]      FIG. 4  illustrates a further prior art arrangement which seeks to alleviate the friction and sticking problems exhibited by the system shown in  FIG. 3 . In this case the single long transverse hole in carrier  120  riding on rail  112  is replaced by two shorter segments with transverse holes  122 . This arrangement is an improvement over the system shown in  FIG. 3  in that it reduces overall friction however it fails to provide repeatable control over that friction. Further it is still prone to the problems involved with lubricants of the carrier and rail. 
         [0008]    In prior art automated luminaire slide systems the manufacturers have been forced by operating conditions to provide additional mechanical means to provide a controlled amount of friction or dampening to the movement of the carrier on the rail in order to minimize hysteresis. Typically this takes the form of an adjustable spring loaded plunger (not shown) providing force onto the rail or a friction collar clamping on to the rail with an adjustable amount of force. Both these systems are prone to poor adjustment and drift in adjustment as the fixture ages and is maintained. 
         [0009]    There is a need for an improved lens slide system for automated luminaire which provides controllable and repeatable friction or dampening in the movement of the lens. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    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: 
           [0011]      FIG. 1  illustrates a typical automated lighting system; 
           [0012]      FIG. 2  illustrates a typical internal components of an automated luminaire; 
           [0013]      FIG. 3  illustrates a prior art slide rail system; 
           [0014]      FIG. 4  illustrates a further prior art slide rail system; 
           [0015]      FIG. 5  illustrates a plan view of an embodiment of the invention; 
           [0016]      FIG. 6  illustrates an elevation view of the lens carrier slide; 
           [0017]      FIG. 7  illustrates a sectional view of the lens carrier slide; 
           [0018]      FIG. 8  illustrates a sectional view of a further embodiment of the lens carrier slide; 
           [0019]      FIG. 9  illustrates a further embodiment of the invention; 
           [0020]      FIG. 10  illustrates a further embodiment of the invention employing a single slide rail; 
           [0021]      FIG. 11  illustrates a side view of the embodiment illustrated in  FIG. 10 ; and 
           [0022]      FIG. 12  illustrates a further embodiment of the single slide rail embodiment of  FIG. 10  with a slide rail with another cross-sectional shape. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    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. 
         [0024]    The present invention generally relates to an automated luminaire, specifically to the configuration and control of the linear movement of lenses within such a luminaire and discloses simplified means to provide a controlled and repeatable friction or dampening on the movement of such a lens without introducing an opportunity for jamming or sticking of the lens movement. While in the examples the slide system facilitates or guides the linear movement of lenses, the system is also contemplated to move other types of lighting or optical modulating or generating components in an automated luminaire. 
         [0025]      FIG. 5  illustrates a plan view of an embodiment of the invention used to control the movement of a lens assembly  100  along the optical axis  101  of an automated luminaire. Lens  102  is rigidly attached to a lens carrier  104 . Lens carrier  104  rides on a rail  112  such that lens carrier  104  may slide along rail  112  and lens  102  may be positioned as desired along the optical axis through connection  114  with belt  116 . Belt  114  is moved by the rotation of driven pulley  108  and runs on idler  110 . Rail  112  may typically be round in cross section although other cross sections are possible as known in the art and the invention is not so limited. Although the illustrated system uses a belt drive to move the lens carrier the invention is not so limited and other movement systems well known in the art including but not limited to worm drives, shaft drives, gear drives, cam drives, linkage drives may be utilized without departing from the spirit of the invention. Different drive systems have different advantages and disadvantages with respect to speed, hysteresis, smoothness of motion, cost etc. 
         [0026]    Carrier  104  comprises a series of fingers  124  formed by a series of parallel slots  125  in the carrier. Each of the fingers  124  has a transverse hole ( 127  in  FIG. 7 ) that may be the same size, slightly smaller or slightly larger in diameter than rail  112 . If hole  127  is larger than rail  112 , as in the prior art, then friction between the rail and carrier will be low however the carrier will have freedom to move and will vibrate or wobble as the luminaire is moved. If hole  127  is the same size or smaller than rail  112  then hole  127  will grip rail  112  by the resilience of the carrier material acting as a spring, by adjusting the size of the hole and the resilience of the material the amount of this grip and thus the friction may be accurately controlled. The effective length of lens carrier  124  is long along the optical axis  101  and provides a wide support base which serves to minimize any possible rotation of lens carrier  124  on slide  112  while the slots  125  minimize any excessive contact area and allow for expansion and contraction during movement and during temperature changes within the luminaire  12 . Thus the problems of excessive contact area such as jamming or sticking on uneven shafts and contaminant build up are avoided. 
         [0027]    In some embodiments, to further reduce contaminant build up the lens carrier  124  may be manufactured of Nylon 66, PA66 or other similar self-lubricating material. The use of such material reduces the need for lubricant grease and thus removes the greasy surface which attracts dirt and contaminants. 
         [0028]      FIG. 6  and  FIG. 7  illustrate a further aspect of the invention—a longitudinal, slot(s)  126  running the length of the carrier  124  generally parallel to the optical axis. FIG.  6  shows carrier  124  from an elevation view perpendicular to the view in  FIG. 5 .  FIG. 7  shows a sectional view through carrier  124  and rail  112 . Carrier  124  runs on rail  112  and has a longitudinal slot  126  running along its axial dimension parallel to rail  112  and through all the fingers of carrier  124 . In alternative embodiments these slots may be staggered between slots  125  rather than being in one line as illustrated in the figures. 
         [0029]      FIG. 7  further illustrates that that in this embodiment the slide system is a dual or multiple rail system. In some embodiments the rails  112  and  113  and interfaces  124  and  129  with the slide rails  112  and  113  respectively may be equivalent. In other embodiments as illustrated in  FIG. 8  the second rail  113  and lens carrier interface  131  may be a looser fit that merely prevents rotation of the lens carrier and lens about the first slide rail  112  as the lens carrier or the luminaire itself is moved to different positions. 
         [0030]    Carrier interface  124  may be manufactured of a resilient material such that the removal of material in slot  126  allows the fingers to act as springs gripping the rail  112  with a known and pre-defined force. In this case the diameter of the holes through the fingers in carrier  124  may be slightly smaller than the diameter of rod  112  and the slot  126  allows opening up those diameter against the resilience of the material acting as a spring so as to allow rail  112  to pass through the holes. This spring gripping action allows the fingers and thus carrier  124  to have a known and defined friction or dampening in their interaction with rail  112  without the need for any additional friction or dampening devices. Carrier  124  may further be molded to close tolerances so as to maintain a high accuracy on the grip and thus the friction between carrier  124  and rail  112 . This accurate control of friction also ensures known and controllable hysteresis and thus good smooth movement and repeatability. 
         [0031]    A single lens and lens carrier is illustrated in  FIGS. 5 and 6  however the invention is not so limited and, in practice, any number of lenses, carriers and rails may be used so as to provide the same advantages of controlled friction and dampening to a plurality of lenses.  FIG. 9  illustrates a view of a further embodiment of the invention where a first lens  102  and a second lens  202  are mounted to a first carrier  104  and a second carrier  204  each of which runs on their respective rails  112  and  212 . Lens carriers  104  and  204  are manufactured with both the transverse slots forming fingers providing a wide support base without excessive contact area and a longitudinal slot providing the controlled gripping action and thus a controlled friction and dampening. Each carrier  104  and  204  has associated with it a second lens carrier interface  221  and  222  respectively which may run on a second rail to prevent rotation of the lens carrier and lens about the first rail. 
         [0032]    In other embodiments lens carriers may share one or more guide rails. 
         [0033]    In yet further embodiments more than one lens and carrier may be positioned on a single rail.  FIGS. 10 ,  FIG. 11  and  FIG. 12  illustrate exemplar single rail embodiments.  FIG. 10  illustrates an embodiment with a slide rail  312  with a rectangular cross-section. The longitudinal slot(s)  326  in the lens carrier&#39;s slide rail interface  304  can be seen in this view.  FIG. 12  illustrates an embodiment with a slide rail  412  with a triangular cross section. The longitudinal slot(s)  426  in the lens carrier&#39;s slide rail interface  404  can be seen in this view.  FIG. 11  illustrates a view from the side where the slots  225  in the lens carrier interface  304  can be seen. In the embodiments  300  and  400  illustrated in  FIG. 10 ,  FIG. 11  and  FIG. 12  additional slide rails are not necessary. 
         [0034]    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.