Abstract:
A color mixer for producing a colored beam of light in combination with a light source. The color mixer includes a plurality of color media configured to pass a light beam such that the color media may be repositioned relative to one another to produce a color mixing effect resulting in many available combinations of color and hue.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 60/970,636 filed on Sep. 7, 2007. 
    
    
     BACKGROUND 
     The present disclosure relates to a color mixer for producing a colored beam of light, for example, in a theatrical lighting fixture. In theater, stage, and other entertainment production applications, it is often desirable to project a colored light beam. Initially, this was accomplished by using colored glass, followed by colored gelatin. The current term “gel” refers generally to theatrical lighting color filters and is derived from this past use of gelatin as a color-filtering medium. Sheets of dyed polyester (called “gels”) are now standard within the industry for lighting color filter applications. 
     It is also desirable to be able to project more than one color from a single lighting fixture. Rotating color wheels provided multiple colors, however, such color wheels proved to be too large, and too limited in the number of colors available. 
     A further desirable feature is the ability to produce a colored light beam of varying hues. For example, it may be desirable to project a light beam at a stage in colors ranging from white light to a very deep shade of blue, symbolizing a transition from day to night. Gel strings accomplish this transition by comprising an assembly of numerous individual frames of color attached together to create a gel having a color gradient ranging from clear to a deep hue of a particular color, such as blue in the previous example. 
     Gel strings may be used in combination with a motor drive system to remotely position the desired color in front of a light source. Such motor drive systems are referred to as color scrollers and are commercially available, such as the Smart Color® line of scrollers from Apollo Design Technology, Inc. of Fort Wayne, Ind. However, color scrollers are limited to the number of individual frames that can be coupled together, thus limiting the color gradient. The highest number of frames available on color scrollers is presently 32. Designers of theatrical programs frequently need more colors than the limited palette offered by current products. 
     SUMMARY 
     The present disclosure relates to a color mixer having a plurality of color media configured to pass a light beam such that the color media may be repositioned relative to one another to produce a color mixing effect resulting in many available combinations of color and hue. 
     The color mixer of the present disclosure employs a plurality of color media. The exemplary embodiment contains two color media, each color media comprising a gel string. One gel string contains graduated frames of cyan and yellow. The second gel string contains graduated frames of yellow and magenta. By combining a magenta frame with a yellow frame a shade of red is produced. Combinations of magenta and cyan produce blue while combinations of yellow and cyan produce greens. 
     Each of the gel strings includes a selection of hues in gradients of the cyan, yellow and magenta frames. The makeup of these two gel strings greatly increases the number of hues available in the ranges that the human eye is most sensitive. The human eye can detect extremely small changes in blue, purple and red hues. However, the eye can only detect large changes in yellow and greens. This phenomenon is documented in a color graphic known as the MacAdam ellipses. See MacAdam, D. L.,  Visual Sensitivities to Color Differences in Daylight , J. Opt. Soc. Am. (1942). Therefore, it is desirable to have a two-string color-mixing device that creates a large quantity of incrementally small changes in blues, purples and reds. It is also desirable for a two-string color-mixing device that creates a small quantity of incrementally large changes in greens and yellows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will be described hereafter with reference to the attached drawings which are given as non-limiting examples only, in which: 
         FIG. 1  is a representation of the placement of the color mixer of the present disclosure in relation to a light source and the placement of the color media in the mixer; 
         FIG. 2  represents the layout of the color media; 
         FIG. 3  shows the color media positioned to create a clear light; 
         FIGS. 4A ,  4 B and  4 C show the color media positioned to create many hues of cyan, yellow and magenta. 
         FIGS. 5A ,  5 B and  5 C show the color media positioned to create many hues of red and blues while limiting the creation of unnecessary greens. 
     
    
    
     DETAILED DESCRIPTION 
     The color mixer  100  of the present disclosure is shown relative to a light source  101  and its associated light beam  102  in  FIG. 1 . The nature of a light beam in a theatrical light is such that the light beam width is most narrow nearest to the light source and increases as the distance from the light increases. Color mixer  100  includes a housing  110 , including a first aperture  103  positioned on the side of the housing nearer light source  101  and a second aperture  104  opposite the first aperture. Light beam  102  is projected from the light source  101  and is passed through a first aperture  103  located proximate to light source  101 , a first color medium  201 , a second color medium  202 , and a second aperture  105  and arrives at a projection surface  105 . First aperture  103  is configured to be smaller than second aperture  104  due to the smaller diameter of light beam  102  nearer light source  101 . 
     Color mixer  100  includes spools  106  and  107  to facilitate moving first color medium  201 . Color mixer  100  also includes spools  108  and  109  to facilitate moving second color medium  202 . In the exemplary embodiment, spools  106 ,  107 ,  108 , and  109  may be motorized and coupled to a controller allowing an operator to remotely position first and second color media  201 ,  201  relative to each other and light source  101 . Various portions of  201  can be positioned in the light beam  102 . 
     First and second color media  201 ,  202  are positioned adjacent and apart from each other within color mixer  100 , as shown in  FIG. 1 . In the present disclosure, the selection of hue, percentage of saturation, and frame quantity, of each of the cyan, yellow and magenta frames have been chosen to take advantage of how the human eye perceives hue. The human eye is more sensitive to changes in hues of indigo, blues and reds. The human eye is less sensitive to orange, yellows and greens.  FIG. 2  shows a vertical representation of color media  201  and  202 . In the exemplary embodiment, each color medium comprises a plurality of color frames. Color medium  201  takes advantage of being closer to the light source  101 . Since the light beam  102  is narrower at this point, the width of the color frames can be narrower. More frames can then be assembled while limiting the overall length of the gel string. 
     First color medium  201  includes a plurality of color frames, including a clear frame  203 , a plurality of yellow hue frames  204 , and a plurality of cyan hue frames  207 . Clear frame  203  is positioned near the midpoint of color medium  201 . Section  204  is made up of a plurality of yellow hue frames, having the lightest yellow hue  205  adjacent clear frame  203  and deepest yellow hue  206  at one end of color medium  201 . Section  207  is made up of a plurality of cyan hue frames, having the lightest cyan hue  208  adjacent clear frame  203  and deepest cyan hue  206  at the opposite end of color medium  201 . 
     Second color medium  202  is positioned farther from the light source  101  than color medium  201 . Since the light beam  102  is wider as it passes through color medium  202 , the width of the color frames must be wider. Fewer frames can be assembled to limit the overall length of the gel string. 
     Second color medium  202  includes a plurality of color frames, including a clear frame  210 , a plurality of magenta hue frames  211 , and a plurality of yellow hue frames  214 . Clear frame  210  is positioned offset from the midpoint of the color medium  202  due to the second color medium  202  having more magenta frames  211  than yellow frames  214 . Section  211  is made up of a plurality of magenta hue frames, having the lightest magenta hue  212  adjacent clear frame  210  and deepest magenta hue  213  at one end of color medium  202 . Section  214  is made up of a plurality of yellow hue frames, having the lightest yellow hue  215  adjacent clear frame  210  and deepest yellow hue  216  at the opposite end of color medium  202 . There are a fewer number of yellow hue frames included in section  214 , than for the other sections  204 ,  207 , and  211 . This results in a shorter color medium  202  and limits creation of an unnecessary amount of green hues. 
     To produce a beam of white light, first color medium  201  and second color medium  202  are configured such that clear frames  203  and  210  are aligned, allowing light beam  102  to pass through color mixer  100  without filtering, as shown in  FIG. 3 . With color media  201  and  202  configured in this arrangement, the light beam  102  projects onto projection surface  105  as white light. 
       FIGS. 4A-4C  show the color media  201 ,  202  configured to produce the various primary colors of yellow, cyan, and magenta. To produce a yellow light beam, first color media is configured such that a frame of yellow section  204  of the first color medium  201  is aligned with clear frame  210  of the second color medium  202 , as shown in  FIG. 4A . In this configuration, light beam  102  is filtered as it passes through yellow section  204  and clear frame  210 , resulting in a yellow light projecting onto projection surface  105 . In this configuration, first color medium  201  may be adjusted based on the desired depth of color desired from the lightest yellow hue  205  to the deepest yellow hue of frame  206 , including any of the frames of varying yellow hue therebetween. This allows any hue of yellow to be produced at projection surface  105 . 
     To produce a cyan light beam, first color media is configured such that a frame of cyan section  207  of the first color medium  201  is aligned with clear frame  210  of the second color medium  202 , as shown in  FIG. 4B . In this configuration, light beam  102  is filtered as it passes through cyan section  207  and clear frame  210 , resulting in a cyan light projecting onto projection surface  105 . In this configuration, first color medium  201  may be adjusted based on the desired depth of color desired from the lightest cyan hue  208  to the deepest cyan hue of frame  2096 , including any of the frames of varying cyan hue therebetween. This allows any hue of cyan to be produced at projection surface  105 . 
     To produce a magenta light beam, first color medium  201  is configured such that clear frame  203  is aligned with a frame of magenta section  211  of the second color medium  202 , as shown in  FIG. 4C . In this configuration, light beam  102  is filtered as it passes through magenta section  211  and clear frame  203 , resulting in a magenta light projecting onto projection surface  105 . In this configuration, second color medium  202  may be adjusted based on the desired depth of color desired from the lightest magenta hue  212  to the deepest magenta hue of frame  213 , including any of the frames of varying magenta hue therebetween. This allows any hue of magenta to be produced at projection surface  105 . 
       FIGS. 5A-5C  show the color media  201 ,  202  configured to mix the various primary colors of yellow, cyan, and magenta to produce red, green, and blue hues. To produce a red light beam, first color medium  201  is configured such that a frame of yellow section  204  is aligned with a frame of magenta section  211  of the second color medium  202 , as shown in  FIG. 5A . In this configuration, light beam  102  is filtered as it passes through yellow section  204  and magenta section  211 , resulting in a red light projecting onto projection surface  105 . In this configuration, since sections  204  and  211  each vary in hue from light to deep, first and second color media  201  and  202  may be adjusted based on the desired depth of color desired and shade of red desired. 
     To produce a green light beam, first color medium  201  is configured such that a frame of cyan section  207  is aligned with a frame of yellow section  214  of the second color medium  202 , as shown in  FIG. 5B . In this configuration, light beam  102  is filtered as it passes through cyan section  207  and yellow section  214 , resulting in a green light projecting onto projection surface  105 . In this configuration, since sections  207  and  214  each vary in hue from light to deep, first and second color media  201  and  202  may be adjusted based on the desired depth of color desired and shade of green desired. Since section  207  varies in hue from  208  to  209  and section  214  has limited hues from  215  to  216 , a limited number of greens can be produced at projection surface  105 . This limitation is desirable since the human eye only detects large changes in green, requiring only limited green gradations. 
     To produce a blue light beam, first color medium  201  is configured such that a frame of cyan section  207  is aligned with a frame of magenta section  211  of the second color medium  202 , as shown in  FIG. 5C . In this configuration, light beam  102  is filtered as it passes through cyan section  207  and magenta section  211 , resulting in a blue light projecting onto projection surface  105 . In this configuration, since sections  207  and  211  each vary in hue from light to deep, first and second color media  201  and  202  may be adjusted based on the desired depth of color desired and shade of blue desired. 
     As should be apparent, by adjusting color media  201 ,  202  to align various hues of yellow, cyan, and magenta, along with the clear frames, a full spectrum of colored light may be produced. Additionally, it is contemplated that color media  201  and  202  comprise colored portions comprising sections of continuously variable color gradient, instead of discrete hue frames. A color medium having such a continuously variable color gradient has colored sections  204 ,  207 ,  211 , and  214  that gradually deepen in hue without a perceptible step in gradation. It is further contemplated that more than two color media may be utilized and still be within the scope of the present disclosure. For example, three color media may be used, one color media for each of the yellow, cyan, and magenta hues. Also, the present disclosure is not limited to theatrical gel strings, but may employ any suitable color filter media. 
     While an embodiment has been illustrated and described in the drawings and foregoing description, such illustrations and descriptions are considered to be exemplary and not restrictive in character, it being understood that only an illustrative embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. The applicant has provided description and figures, which are intended as an illustration of certain embodiments of the disclosure, and are not intended to be construed as containing or implying limitation of the disclosure to those embodiments. There are a number of advantages of the present disclosure arising from various features set forth in the description. It will be noted that alternative embodiments of the disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of the disclosure and associated methods that incorporate one or more of the feature of the disclosure and fall within the spirit and scope of the present disclosure as defined by the impendent claims.