Abstract:
Systems and methods are disclosed that include overlapping a first portion of a first piece of flexible filter material and a second portion of a second piece of flexible filter material. In these systems and methods, the first and second pieces of flexible filter material produce a desired change in a characteristic of a light beam. These systems and methods can include clamping the first portion and the second portion between a first element and a second element. In addition, these systems and methods can include producing ultrasonic vibrations in the first element that promotes a bond between the first and second piece of flexible filter material.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is related to and claims priority to U.S. Provisional Patent Application Ser. No. 61/011,556, entitled “Method and Apparatus for Fabricating a Gel String,” filed on Jan. 18, 2008, which is assigned to the assignee of the present application. The subject matter disclosed in Provisional Patent Application Ser. No. 61/011,556 is hereby incorporated by reference into the present disclosure as if fully set forth herein. The present application hereby claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 61/011,556. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to automated lighting equipment, and in particular, to a method and apparatus of fabricating a gel string. 
       BACKGROUND 
       [0003]    Characteristics such as color and beam shape of a light beam emitted by a light fixture may be controlled with filter materials placed in the light beam. Where the light beam has a round cross section, a rectangular piece of filter material may be placed across the light beam. Because some color filter material was originally made of a gelatin-based substance, such color filters came to be commonly referred to as ‘gels.’ The term ‘gel’ is now also used to refer to flexible filter material that changes other characteristics of a light beam than color, such as diffusion and/or beam divergence. 
         [0004]    Because gels and other filter materials are flexible, two or more such pieces may be fastened together at their edges to form a sequence of pieces of filter material. Such a sequence of pieces of filter material may be referred to as a ‘gel string.’ Each end of such a gel string may be wrapped around a cylinder and the cylinders positioned on opposite sides of the light fixture with the portion of the gel string between the cylinders positioned across the light beam. By providing the cylinders with motors and a controller, the gel string may be scrolled between the cylinders to position a desired portion of the gel scroll across the light beam. Such a mechanism may be referred to as a ‘gel scroller’ and enables desired characteristics of a light beam to be modified by positioning a desired piece of filter material in the beam. 
       SUMMARY 
       [0005]    In one embodiment, a methods is disclosed that includes overlapping a first portion of a first piece of flexible filter material and a second portion of a second piece of flexible filter material. In this method, the first and second pieces of flexible filter material produce a desired change in a characteristic of a light beam. This method also includes clamping the first portion and the second portion between a first element and a second element. In addition, this method can include producing ultrasonic vibrations in the first element that promotes a bond between the first and second piece of flexible filter material. 
         [0006]    In another embodiment, a gel string prepared by a process is disclosed. This process includes providing a first portion of a first piece of flexible filter material, providing a second portion of a second piece of flexible filter material, and clamping the first portion and the second portion between a first element and a second element. In addition, this process further includes producing ultrasonic vibrations in the first element, whereby the first portion and the second portion are bonded. 
         [0007]    In yet another embodiment, a system is disclosed that includes a first filter material that creates a first alteration of at least one characteristic of a light beam passing through the first filter material. This system also includes a second filter material that creates a second alteration of at least one characteristic of the light beam passing through the first filter material. In addition, this system includes a bond that includes at least part of the first filter material and at least part of the second filter material. This bond is created in situ through energy transferred to the first filter material and secures an overlap area of the first filter material and the second filter material. 
         [0008]    The foregoing has outlined rather broadly the features and technical advantages of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they may readily use the conception and the specific embodiment disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form. 
         [0009]    Before undertaking the DETAILED DESCRIPTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior uses, as well as to future uses, of such defined words and phrases. 
     
    
     
       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 descriptions taken in conjunction with the accompanying drawings, wherein like numbers designate like objects, in which: 
           [0011]      FIG. 1  shows a front view of an apparatus according to the present disclosure for fastening together pieces of filter material; 
           [0012]      FIG. 2  depicts a top view of the apparatus OF  FIG. 1 ; 
           [0013]      FIG. 3  shows a gel string fabricated according to the present disclosure; and 
           [0014]      FIG. 4  depicts an automated lighting fixture including a gel string of the type shown in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0015]      FIGS. 1 through 4 , discussed below, and the various embodiments used to describe the principles of the present invention in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the invention. Those skilled in the art will understand that the principles of the invention may be implemented in any suitably arranged gel string fabrication device. 
         [0016]      FIG. 1  shows a front view of an apparatus  100  according to the present disclosure for fastening together pieces of filter material. An ultrasonic welding assembly  102  includes an ultrasonic transducer  103  and a horn  104 . The transducer  103  converts electrical energy received via electrical conductor  105  into ultrasonic mechanical vibrations. The vibrations are transferred via the horn  104  to a surface  122 . Any known technique for producing ultrasonic vibrations in the surface  122  may be used without departing from the scope of the present disclosure. 
         [0017]    The apparatus  100  also includes an anvil  105  that is positioned opposite the ultrasonic welding assembly  102  and has a surface  124  positioned opposite the surface  122 . The anvil  105  cooperates with the assembly  102  in the fastening process. Pieces of filter material  106  and  108  are overlapped and the overlapped portion positioned between the horn  104  and the anvil  105 . The pieces  106  and  108  are supported on each side of the anvil  105  by supports  111  and  110 , respectively. The anvil  105  and the supports  110  and  111  are attached to a common base  112 . It will be understood that the supports  110  and  111  may be mounted to separate bases without departing from the scope of the present disclosure. 
         [0018]    A distance between the ultrasonic welding assembly  102  and the anvil  105  is controlled by a positioning mechanism  114 . In a preferred embodiment, the positioning mechanism  114  includes a piston  118 , mechanically coupled to the ultrasonic welding assembly  102 , operable to move within a cylinder  116 , which is fixed in position relative to the anvil  105 . The position of the piston  118  within the cylinder  116  may be controlled hydraulically via a conduit  120  coupled to the cylinder  116 . As the piston  118  moves within the cylinder  116 , the ultrasonic welding assembly  102  is moves closer to or farther from the anvil  105 . Other mechanisms than a hydraulic mechanism may be used to position the ultrasonic welding assembly  102  relative to the anvil  105  without departing from the scope of the present disclosure. 
         [0019]    In operation, once the pieces of filter material  106  and  108  are overlapped and positioned between the horn  104  and the anvil  105 , the positioning mechanism  114  is operated to clamp the pieces  106  and  108  with a desired pressure. At the same time, electrical power is applied to the ultrasonic transducer  103  and the resulting ultrasonic vibrations of the surface  122  generates frictional heat in the piece  106  of filter material. One or both of the pieces  106  and  108  soften or melt, forming a bond between the pieces  106  and  108 . It will be understood that other known techniques of heating the pieces  106  and/or  108  in a controlled manner may be used without departing from the scope of the present disclosure. 
         [0020]    The pressure applied to the pieces  106  and  108  by the horn  104  and the anvil  105  is controlled, along with the duration of the ultrasonic vibrations, to securely fasten the pieces  106  and  108  together, without resulting in burn-through or significant weakening of the material. A desired pressure and duration may be determined based upon a thickness and type of material of each of the pieces  106  and  108 . 
         [0021]      FIG. 2  depicts a top view of the apparatus  100 . The anvil  105  is positioned between the supports  110  and  111 . The pieces of filter material  106  and  108  are overlapped and laid on the anvil  105  and the supports  110  and  111 . Above the pieces  106  and  108  is the ultrasonic transducer  103 . The outlines of the horn  104  and the surface  122  are depicted by broken lines. Not shown in  FIG. 2  are the base  112  and the positioning mechanism  114 . 
         [0022]    As shown in  FIG. 2 , the surface  124  of the anvil  105  may have a texture to improve the ultrasonic fastening process or the resulting bond between the pieces  106  and  108 . Similarly, the surface  122  of the horn  104  may be textured. 
         [0023]    As also shown in  FIG. 2 , the horn  104  may be smaller along its long dimension (in the vertical direction, as shown in  FIG. 2 ) than is the anvil  105 . When the pieces of filter material  106  and  108  are wider than the horn  104 , the fastening process is performed in stages. A first area of the overlapped portion of the pieces  106  and  108  is clamped between the horn  104  and a corresponding portion of the anvil  105  and fastened. The horn is then lifted and repositioned along the anvil  105  to fasten a second area of the overlapped portion of the pieces  106  and  108 . The first and second areas may overlap, in order to compensate for any variation in quality of the bond between the pieces  106  and  108  at the ends of the horn  104 . 
         [0024]    In other embodiments, the horn  104  and the anvil  105  may both be shorter than the width of the pieces  106  and  108  and may both be moved in order to fasten the pieces  106  and across their width. In other such embodiments, the pieces and  108  may be moved relative to the horn  104  and the anvil  105  in order to fasten the pieces  106  and  108  across their width. 
         [0025]      FIG. 3  shows a gel string  300  such as may be fabricated with the apparatus  100  of  FIGS. 1 and 2 . Pieces and  304  of filter material have been overlapped and fastened (or welded) along a seam  306 . Where the overlap between the pieces  302  and  304  extends beyond the seam  306 , one or more portions of pieces  302  and  304 , such as corner  307  and/or edge  309 , may be left un-welded. Once the gel string  300  is mounted in a gel scroller, the corner  307  or the edge  309  may catch on a part of the scroller when the gel string  300  is in motion, resulting in a weakening or tearing of the seam  306 . To eliminate, or reduce the incidence of, such occurrences, adhesive tape  308  and  310 , or other material, may be placed around the outer edges of the gel string  300  in the vicinity of the corner  307 , to cover the corner  307  and/or a part of the edge  309 . 
         [0026]    While the seam  306  is shown in  FIG. 3  positioned orthogonally across the pieces  302  and  304 , it will be understood that the seam may be positioned at other angles than 90 degrees to the edges of the pieces  302  and  304  of filter material. Similarly, while the seam  306  and the adjacent edges of the pieces  302  and  304  are shown as straight lines, it will be understood that other shapes and configurations may be used, such as a zig-zag edges and/or seams. 
         [0027]      FIG. 4  depicts a gel scroller  400  having mounted therein a gel string  402  of the type shown in  FIG. 3 . The gel string is wrapped at opposite ends around cylinders  406  and  410 , respectively. The cylinders  406  and  410  are mounted to rotate around axes  408  and  412 , respectively. A portion of the gel string  402  extending between the cylinders  406  and  410  extends across an aperture of a light fixture  403  and the light beam emitted by the light fixture  403 . Motors and a controller (not shown in  FIG. 4 ) may be coupled to the cylinders  406  and  410  and operated to position a desired portion of the gel string  402  across the light beam emitted by the light fixture  403 . 
         [0028]    As shown in  FIG. 4 , the gel string  402  may be positioned such that a seam  404  is across the aperture of the light fixture  403 . The two filter pieces joined by the seam  404  may be color filters having differing colors and a subsequent optical element (not shown in  FIG. 4 ) may blend or homogenize the two colors in the light beam into a single combined color. In such an embodiment, the location of the seam  404  would determine how much of each color filter was located across the light beam, thereby determining the color of the blended light beam. 
         [0029]    The portion of the gel string  402  that is positioned across the light beam emitted by the light fixture  403  will absorb some of the light energy in the beam, resulting in heating of that portion of the gel string  402 . Some other techniques for joining pieces of filter material to form a gel string result in a fastening that degrades when heated in this way. For example, the adhesive coating on adhesive tape used to join two pieces of filter material may fail when heated, resulting in such a gel string breaking. Even if the adhesive does not fail, the tape may discolor, resulting in an undesired color of the light beam. However, a gel string fabricated according to the method of the present disclosure places no material other than the filter material in the light beam and the welding process of the present disclosure may be performed so as not to weaken the filter material, with the result that any portion of the gel string  402  may be positioned in the light beam and suffer heat degradation at substantially the same rate as the individual pieces of filter material. 
         [0030]    Although the present invention and its advantages have been described in the foregoing detailed description and illustrated in the accompanying drawings, it will be understood by those skilled in the art that the invention is not limited to the embodiment(s) disclosed but is capable of numerous rearrangements, substitutions and modifications without departing from the spirit and scope of the invention as defined by the appended claims.