Patent Publication Number: US-7896525-B2

Title: Heat resistant color mixing flag for a multiparameter light

Description:
CROSS REFERENCE TO RELATED APPLICATION(S) 
     The present application is a divisional of and claims the priority of U.S. patent application Ser. No. 11/765,539, titled “HEAT RESISTANT COLOR MIXING FLAG FOR A MULTIPARAMETER LIGHT”, filed on Jun. 20, 2007 now U.S. Pat. No. 7,832,902. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to multiparameter lighting fixtures. 
     BACKGROUND OF THE INVENTION 
     Multiparameter lighting fixtures are lighting fixtures, which illustratively have two or more individually remotely adjustable parameters such as focus, color, image, position, or other light characteristics. Multiparameter lighting fixtures are widely used in the lighting industry because they facilitate significant reductions in overall lighting system size and permit dynamic changes to the final lighting effect. Applications and events in which multiparameter lighting fixtures are used to great advantage include showrooms, television lighting, stage lighting, architectural lighting, live concerts, and theme parks. Illustrative multi-parameter lighting fixtures are described in the product brochure showing the High End Systems product line for the year 2000 and are available from High End Systems, Inc. of Austin, Tex. 
     Multiparameter lighting fixtures are commonly constructed with a lamp housing that may pan and tilt in relation to a base housing so that light projected from the lamp housing can be remotely positioned to project on a stage surface. Commonly a plurality of multiparameter lights are controlled by an operator from a central controller. The central controller is connected to communicate with the plurality of multiparameter lights via a communication system. U.S. Pat. No. 4,392,187 titled “Computer controlled lighting system having automatically variable position, color, intensity and beam divergence” to Bornhorst, incorporated herein by reference, discloses a plurality of multiparameter lights and a central controller. 
     The lamp housing of the multiparameter light contains the optical components and the lamp. The lamp housing is rotatably mounted to a yoke that provides for a tilting action of the lamp housing in relation to the yoke. The lamp housing is tilted in relation to the yoke by a motor actuator system that provides remote control of the tilting action by the central controller. The yoke is rotatably connected to the base housing that provides for a panning action of the yoke in relation to the base housing. The yoke is panned in relation to the base housing by a motor actuator system that provides remote control of the panning action by the central controller. 
     It is desirable for a multiparameter light to have a high intensity light output and a remotely variable color system. The use of dichroic filters to color the light emitted by a multiparameter theatre lighting fixture is known in the art. U.S. Pat. No. 4,392,187 to Bornhost, discloses the use of dichroic filters in a multiparameter light. Bornhorst writes “The dichroic filters transmit light incident thereon and reflect the complement of the color of the transmitted beam. Therefore, no light is absorbed and transformed to heat as found in the prior art use of celluloid gels. The use of a relatively low power projection lamp in lights 30 and 110 substantially reduces the generation of infrared radiation which causes high power consumption and heat buildup within prior art devices.” 
     Bornhorst U.S. Pat. No. 4,392,187 was filed in March 1981 and since that time the use of dichroic filters to color the light emitted by a multiparameter stage light is generally practiced in the art. One thing has continued to change however. There is an on going demand within the theatre industry for ever increasing light output levels from multiparameter theater lights. Therefore, the projection lamp source for the modern day multiparameter light has been increasing in power and light output. For example while the lamp 50 disclosed by Bornhorst is a common projector lamp having a power consumption of 350 watts, there is a demand today for multiparameter lights utilizing lamps that have a power consumption of 2000 Watts and over. 
     Bornhorst discloses color wheels 112 and 114 that have dichroic filters mounted thereon and permit the coloring of the light emitted by a lamp  50 . While the use of color wheels that support multiple wavelengths of dichroic filters to color the light of a multiparameter stage light is still in common practice, it is also common practice to construct a multiparameter light having variable density dichroic filter flags that gradually color the light using a subtractive color method. The subtractive color method may use the dichroic filter flag colors of cyan, magenta and yellow to gradually and continuously vary the color of today&#39;s multiparameter stage light producing a pleasing color fade when visualized by an audience. The gradual and continuous varying of cyan, magenta and yellow in the light path of a multiparameter light is referred to as “CMY color mixing” in the theatrical art. 
     U.S. Pat. No. 6,687,063 to Rasmussen discloses a dichroic color mixing filter flag system for use with a multiparameter light color mixing system. Rasmussen discloses a dichroic color mixing flag in FIGS. 8 and 12 with dichroic etched fingers that operate to produce a variable color as they are translated across the light created by the optical path. 
     Current state of the art dichroic color mixing flags are constructed of a low expansion borosilicate glass substrate. The low coefficient of expansion of the borosilicate glass substrate helps to provide a reasonable tolerance to thermal shock as the dichroic color mixing flag is translated or moved into and out of the high energy light created by the optical path. A low expansion borosilicate glass substrate use in the manufacture of dichroic filter flags is commercially available from Schott America, 555 Taxter Road, Elmsford, N.Y. and is referred to as Schott Borofloat. 
     The inventors of the present application have noticed during development of new multiparameter stage lights using lamps having a wattage of 2000 watts and over, that the dichroic color mixing flags of the present art constructed on the present art borosilicate substrate are subject to even greater thermal shock and therefore can crack when used with such high intensity light sources. One prior art way to improve the thermal (or heat) resistance of the present art dichroic color mixing flag is to construct the dichroic filter material out of a substrate with an even lower coefficient of thermal expansion than the typical borosilicate. Unfortunately, in the prior art, this improved alternate type of substrate is usually constructed from a high purity quartz, which can be very custom and be quite expensive. 
     SUMMARY OF THE INVENTION 
     At least one embodiment of the present invention includes a method of constructing a dichroic color mixing flag for a multiparameter light that greatly improves the thermal shock tolerance of the flag and avoids having to use a more costly quartz substrate material as in the prior art. 
     At least one embodiment of the present invention includes a novel method of improving the shock tolerance of a color mixing flag used in a multiparameter light. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a simplified diagram of a prior art dichroic color mixing flag; 
         FIG. 2A  shows a simplified diagram of a prior art system of dichroic color mixing flags in a first state; 
         FIG. 2B  shows a simplified diagram of the prior art system of color mixing flags of  FIG. 2A  in a second state; 
         FIG. 3  shows a simplified diagram of a dichroic color mixing flag in accordance with an embodiment of the present invention; 
         FIG. 4A  shows a simplified diagram of a system of dichroic color mixing flags in accordance with another embodiment of the present invention in a first state, wherein the dichroic color mixing flags can be translated into a light path; and 
         FIG. 4B  shows a simplified diagram of the system of dichroic color mixing flags of  FIG. 4A  in a second state, wherein the dichroic color mixing flags have been translated into a light path. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a simplified diagram of a dichroic color mixing flag  100  of the prior art. The dichroic color mixing flag  100  is fixed to a mechanical component, such as mechanical arm  102  used as a holder and for translation into a path of light from a multiparameter light. The fixing of the color mixing flag  100  may be through or by any suitable way known in the art such as by high temperature silicone adhesive to area  104  of the mechanical arm  102 . The flag  100  has a graduated area  108  where a dichroic film is patterned to aid in the gradual color mixing when the dichroic color mixing flag  100  is translated into the path of light from a multiparameter light as known in the art. The flag  100  also has an area  106 . 
       FIG. 2A  shows a simplified diagram of a dichroic color mixing system  200  of the prior art in a first state. The dichroic color mixing system  200  uses two dichroic color mixing flags  210  and  220  each of which is similar to dichroic color mixing flag  100  of  FIG. 1 . The dichroic color mixing flags  210  and  220  are fixed to mechanical components, such as mechanical arms  212  and  222 , respectively, each of which may be the same arm as mechanical arm  102  of  FIG. 1 . The mechanical arm  212  is fixed to a motor shaft  216  of motor  214  so that the mechanical arm  212  and flag  210  may be variably translated in the direction D 1  into the optical path of light  230 . The mechanical arm  222  is fixed to motor shaft  226  of motor  224  so that the arm  222  and flag  220  may be variably translated in the direction D 2  into the optical path of light  230 . The optical path of light  230  is the path of light created by the optical system of a prior art multiparameter light. 
       FIG. 2B  shows the dichroic color mixing system  200  in a second state. In the second state shown in  FIG. 2B , the dichroic color mixing flags  210  and  220  have been fully translated into the optical path of light  230 . 
     In the prior art, dichroic color mixing flags, such as  100 ,  210 , or  220 , have been constructed primarily rectangular or square in geometry. This is quite natural since it is desirable to have a long fixing area for gluing such as the area  104  of the flag  100 . Generally, the term “color mixing flag” is associated by with a rectangular or a square shape. This can be easily seen when observing the geometry of the color mixing flags of FIG. 12 of U.S. Pat. No. 6,687,063 to Rasmussen and 505 of FIG. 5 of U.S. Pat. No. 6,796,683 to Wood for example. During the development of a high powered multiparameter light using a lamp of 2000 watts or greater the inventors of the present application realized that the prior art dichroic color mixing flags (such as flag  100  of  FIG. 1 ) often cracked due to thermal stress when translated into a light path across such intense light. It was not desirable to change the substrate material to that of a lower expansion from a material like quartz because the price of the quartz substrate is quite expensive and not readily available. 
     Experimentation began with varying thicknesses of a borosilicate dichroic color mixing flag, to find a solution. The fixing or gluing area  104  used for the flag  100  of shown in  FIG. 1  was altered as a means to allow the substrate further room for expansion as it was translated into the light path. An experiment to sectionalize the dichroic color mixing flag  100  of  FIG. 1  into multiple smaller strips of material was tried without significant improvement of the flag as modified, to handle thermal stress when translated into a light path, such as  230  of  FIG. 2B . 
     The inventors found that a dichroic color mixing flag of a borosilicate substrate could be constructed that greatly improved the handling of thermal stress by altering the geometry of the color mixing flag  100  of the prior art. In one embodiment of the present invention a dichroic color mixing flag  300  is constructed having a substantially circular geometry. The color mixing flag  300  of  FIG. 3  shows a great improvement to handling thermal stress in multiparameter lights with highpowered light sources. In one embodiment of the present invention, which may be preferred, a substantially circular dichroic color mixing flag  300  is provided. However, a dichroic color mixing flag that is substantially elliptical or substantially predominantly oval are also embodiments of the present invention, and will produce a somewhat improved color mixing flag over the prior art. 
       FIG. 3  shows the dichroic color mixing flag  300  of an embodiment of the present invention. The dichroic color mixing flag  300  is shaped to a substantially circular geometry. The dichroic color mixing flag  300  is fixed to a mechanical arm  302  used as a holder and for translation into a path of light from a multiparameter light. The fixing of the color mixing flag  300  may be any suitable way known to the art such as by high temperature silicone adhesive to an area  304  of the mechanical arm  302 . The mechanical arm  302  of  FIG. 3  may be similar in construction to the mechanical arm  102  of  FIG. 1 . The dichroic color mixing flag  300  has a graduated area  308  where dichroic film is patterned to aid in the gradual color mixing when the flag  300  is translated into the path of light of the high powered multiparameter light. The graduated area  308  may be etched and be a pattern of dots or areas of full saturation next to areas of no saturation. The flag  300  also has an area  306 . 
       FIG. 4A  shows a simplified diagram of a dichroic color mixing system  400  in accordance with an embodiment of the present invention in a first state. The dichroic color mixing system  400  uses two dichroic color mixing flags  410  and  420  each of which is similar to dichroic color mixing flag  300  of  FIG. 3 . The dichroic color mixing flags  410  and  420  are fixed to mechanical components, such as mechanical arms  412  and  422 , respectively, each of which may be the same arm as mechanical arm  302  of  FIG. 3 . The mechanical arm  412  is fixed to a motor shaft  416  of motor  414  so that the mechanical arm  412  and flag  410  may be variably translated in the direction D 3  into the optical path of light  430 . The mechanical arm  422  is fixed to motor shaft  426  of motor  424  so that the arm  422  and flag  420  may be variably translated in the direction D 4  into the optical path of light  430 . The optical path of light  430  is the path of light created by the optical system of a multiparameter light. 
       FIG. 4B  shows the dichroic color mixing system  400  in a second state. In the second state shown in  FIG. 4B , the dichroic color mixing flags  410  and  420  have been fully translated into the optical path of light  430 . The translation of the dichroic color mixing flags  410  and  420  may be accomplished, in one embodiment of the present invention, by rotation of the motor shafts  416  and  426  that drive the mechanical arms  412  and  422  to rotate, respectively. The mechanical arm  412  with the flag  410  and the mechanical arm  422  with the flag  420  are rotated into the optical path of the light  430 . 
     Although the invention has been described by reference to particular illustrative embodiments thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. It is therefore intended to include within this patent all such changes and modifications as may reasonably and properly be included within the scope of the present invention&#39;s contribution to the art.