Patent Publication Number: US-2019193113-A1

Title: Irradiation systems for curing targets, related curing systems, and related methods

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application No. 62/609,968, filed Dec. 22, 2017, the content of which is incorporated herein by reference. 
    
    
     FIELD 
     The invention relates to curing of targets, and more particularly, to improved LED based irradiation systems for curing of such targets. 
     BACKGROUND 
     Aspects of conventional lighting and/or curing systems are disclosed in U.S. Pat. Nos. 8,357,878, 9,648,705, U.S. Patent Application Publication No. 2013/0010460, and U.S. Patent Application Publication No. 2013/0114263. 
     It would be desirable to provide improved irradiation systems for curing targets, and methods of designing the same. 
     SUMMARY 
     According to an exemplary embodiment of the invention, an irradiation system is provided. The irradiation system includes a plurality of LED arrays, each of the LED arrays including a plurality of LED light producing elements. The irradiation system also includes a target area, the target area being adapted to receive light energy from each of the plurality of LED arrays. The plurality of LED arrays are positioned with respect to one another such that they surround the target area of the irradiation system. 
     According to another exemplary embodiment of the invention, a curing system for curing a target is provided. The curing system includes a coating system for coating a target, and an irradiation system for curing the target after the target is coated using the coating system. The irradiation system includes (i) a plurality of LED arrays, each of the LED arrays including a plurality of LED light producing elements, and (ii) a target area, the target area being adapted to receive light energy from each of the plurality of LED arrays, wherein the plurality of LED arrays are positioned with respect to one another such that they surround the target area of the irradiation system. 
     According to yet another exemplary embodiment of the invention, a method of designing an irradiation system is provided. The method includes the steps of: (a) providing a target configured for curing using the irradiation system; (b) determining curing characteristics for curing the target, the curing characteristics including at least one of (i) a desired level of irradiation for curing the target and (ii) a target area for receiving energy from the irradiation system; (c) using the curing characteristics to determine a plurality of LED arrays for inclusion in the irradiation system, each of the LED arrays including a plurality of LED light producing elements; and (d) positioning the plurality of LED arrays with respect to one another such that they surround the target area of the irradiation system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is best understood from the following detailed description when read in connection with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawings are the following figures: 
         FIG. 1A  is a block diagram of an optical fiber curing system in accordance with an exemplary embodiment of the invention; 
         FIG. 1B  is a block diagram of an target curing system in accordance with an exemplary embodiment of the invention; 
         FIG. 2  is a partially exploded, perspective view of elements of an irradiation system in accordance with an exemplary embodiment of the invention; 
         FIG. 3A  is a block diagram, end view of elements of another irradiation system in accordance with an exemplary embodiment of the invention; 
         FIG. 3B  is another block diagram, internal view, of elements of the irradiation system of  FIG. 3A ; 
         FIG. 3C  is a side view of a lens element of the irradiation system of  FIG. 3A ; 
         FIG. 4A  is a block diagram, end view, of elements of yet another irradiation system in accordance with an exemplary embodiment of the invention; 
         FIG. 4B  is another block diagram, internal view, of elements of the irradiation system of  FIG. 4A ; and 
         FIG. 5  is a flow diagram illustrating a method of designing an irradiation system in accordance with an exemplary embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     According to aspects of the invention, the lamp/irradiator used to cure a target is designed (e.g., shaped, configured, etc.) to address the specific target requiring curing. This is accomplished, for example: by the placement of the light producing elements/arrays that perform the curing operation (e.g., to surround the target); by the inclusion of specific optical elements (e.g., reflectors, lenses, etc.) placed with respect to the light producing arrays and the target; by the inclusion of reflectors between the light producing arrays; among other features. 
     In certain aspects of the invention, the irradiator/lamp may be mounted on a rotating structure/platen. This permits the irradiator/lamp to be turned during servicing. The lenses (e.g., see  FIGS. 3B and 3C ), and the reflectors (see  FIG. 3B ,  FIG. 4B ) positioned between the LED arrays, are both desirably configured to be easily installed and removed. Likewise, the LED arrays may be configured to be easily removed and replaced. 
     Referring now to the drawings,  FIG. 1A  illustrates an optical fiber curing system  100 . Optical fiber curing system  100  includes a source optical fiber  102 , a coating system  104 , an irradiation system  106  (also referred to herein as an irradiator), and a spool  108 . Source optical fiber  102  is coated at coating system  104 , and then the coating is cured using irradiation system  106 , and then the coated/cured optical fiber is wound on spool  108 . Aspects of the invention described herein relate particularly to irradiation system  106 . 
     While the invention has applicability to optical fiber curing systems (such as optical fiber curing system  100  shown in  FIG. 1A ), the invention is applicable to irradiation systems (and curing systems) for many applications. For example, other targets (other than optical fiber) may be processed using such irradiation systems. Exemplary targets include pipes, cables, ribbon, wire, etc. for which curing of a coating is desired.  FIG. 1B  illustrates a generic target curing system  100 ′ for curing such targets. Target curing system  100 ′ includes a target  102 ′, a coating system  104 ′, and an irradiation system  106 ′ (also referred to herein as an irradiator). Target  102 ′ (e.g., a pipe, a cable, or other target) is coated at coating system  104 ′, and then the coating is cured using irradiation system  106 ′. 
     Irradiation systems  106 / 106 ′ may vary within the scope of the invention described and claimed herein.  FIG. 2  illustrates one exemplary irradiation system  106   a ;  FIGS. 3A-3C  illustrate another exemplary irradiation system  106   b ; and  FIGS. 4A-4B  illustrate yet another exemplary irradiation system  106   c . Either of irradiation systems  106 ,  106 ′ from  FIGS. 1A-1B  could be any of irradiation systems  106   a  ( FIG. 2 ),  106   b  ( FIGS. 3A-3C ),  106   c  ( FIG. 4A-4B ), or any other irradiation system within the scope of the invention. Elements from each of  FIG. 2 ,  FIGS. 3A-3C , and  FIGS. 4A-4C  may be combined, as desired. 
     Referring now specifically to  FIG. 2 , an irradiation system  106   a  is shown in a partially exploded view. Irradiation system  106   a  includes a housing  106   a   1 , and substrate walls  106   a   3 . One or more hinges  106   a   2  connect sections of housing  106   a   1  including substrate walls  106   b   2 . End caps  106   a   5 ,  106   a   6  are provided on each terminal end of housing  106   a   1 . Inside housing  106   a   1 , on substrate walls  106   a   3 , are provided a plurality of LED arrays  106   a   4 , where each of the LED arrays  106   a   4  includes a plurality of LED light producing elements (e.g., ultraviolet LED light producing elements, infrared LED light producing elements, etc., where such elements are not individually labelled in the drawings because of size). The plurality of LED arrays  106   a   4  are arranged to surround quartz tube  106   a   7  (which is configured to house a target, such as an optical fiber, where this tube, and other tubes described herein, may be filled with a gas such as nitrogen or argon in order to purge oxygen to improve curing efficiency due to the mitigation of oxygen inhibition in the photopolymerization reaction, during irradiation by irradiation system  106   a ). In  FIG. 2 , six (6) different LED arrays  106   a   4  are provided (one on each substrate wall  106   a   3 ) to surround quartz tube  106   a   7 . However, in accordance with the invention, any number of LED arrays (such as LED arrays  106   a   4 ) may be provided to surround the target (such as the target housed within quartz tube  106   a   7 ). 
     For example, in a configuration different from that shown in  FIG. 2 , three (3) LED arrays  106   a   4  may be provided to surround quartz tube  106   a   7  (e.g., in each of  FIGS. 3A-3C , and  FIGS. 4A-4B , three LED arrays are provided to surround the target). Returning again to  FIG. 2 , additional optical elements (e.g., lenses, reflectors, etc.) may be provided, as desired to optimize the specific application. For example, lenses may be between each of the LED arrays and the quartz tube (e.g., see lenses  106   b   6  in  FIGS. 3B-3C ). Further, reflectors may be provided between each of the LED arrays (e.g., see reflectors  106   b   7  in  FIG. 3B , or reflectors  106   c   7  in  FIG. 4B ). Further still, primary reflectors may be provided adjacent each LED array to direct light energy toward a target (e.g., see primary reflectors  106   c   6  in  FIG. 4B ). When irradiation system  106   a  is fully assembled (or an irradiation system similar irradiation system  106   a , but with a different number of LED arrays, and/or with any of the aforementioned lenses or reflectors), a coated optical fiber (or other target) enters irradiation system  106   a  via a hole in one end cap  106   a   5  or  106   a   6 , passes through quartz tube  106   a   7 , and exits irradiation system  106   a  via a hole in the other end cap  106   a   5  or  106   a   6 . Through the operation of the LED arrays, the coating previously applied to the target is desirably cured while in quartz tube  106   a   7 . 
       FIG. 3A  illustrates a simplified, end view, of an irradition system  106   b  (the elements within the enclosure are removed for simplicity, but see  FIG. 3B ). Irradiation system  106   b  includes a housing  106   b   1  (which may be similar to housing  106   a   1  in  FIG. 2 , or may vary as desired) including a plurality of wall sections  106   b   2 . While illustrated in a simplified manner, each wall section  106   b   2  may represent a more complex structure, for example: (i) an outside wall portion/structure and an interior wall portion/structure (e.g, an interior substrate wall similar to substrate wall  106   a   3  in  FIG. 2 ); or (ii) a part of an underlying housing such as housing  106   a   1  shown in  FIG. 2 , that supports substrate sections such as substrate wall  106   a   2  in  FIG. 2 . 
     Irradiation system  106   b  includes three (3) light producing arrays  106   b   5  (e.g., LED arrays including a plurality of LED light producing elements), which are visible in  FIGS. 3B-3C . As shown in  FIG. 3A  (when viewed in connection with  FIG. 3B ), a heatsink  106   b   3  along with a corresponding cooling element  106   b   4  (e.g., a fan), is provided on each of the wall sections  106   b   2  that supports a light producing array  106   b   5  (e.g., an LED array). 
       FIG. 3B  is another end view of irradiation system  106   b , but that shows certain of the internal elements thereof. In the example shown in  FIG. 3B , three (3) light producing arrays  106   b   5  (e.g., LED arrays) are provided, and are positioned with respect to one another to surround a target area  106   b   10  and a target  106   b   8 . In the example shown in  FIG. 3B , target  106   b   8  (e.g., an optical fiber) is provided in a target housing  106   b   9  (e.g., a quartz tube, as in  FIG. 2 ). A desired optical boundary limitation  106   b   10  (e.g., also referred to as target area  106   b   10  for receiving a predetermined level, or profile, of irradiation) is also shown around target  106   b   8  and target housing  106   b   9 . 
     Light producing arrays  106   b   5  (e.g., LED arrays) are each provided on internal portions of wall sections  106   b   2 . A lens element  106   b   6  (also referred to as an optical lens  106   b   6 , detailed in  FIG. 3C ) is positioned between each of the light producing arrays  106   b   5  (e.g., LED arrays) and target  106   b   10  (and target  106   b   8 ). Optical reflectors  106   b   7 , each including an internal curved surface  106   b   7   a  (e.g., for reflecting light back toward target area  106   b   10  and target  106   b   8 ), are provided between each of lens elements  106   b   6 . Light from each light producing array  106   b   5  passes through a respective lens element  106   b   6 , and then on to target area  106   b   10  (and target  106   b   8 ). The inclusion of optical reflectors  106   b   7  between lens elements  106   b   6 , makes irradiation system  106   b  more efficient. Further, the design of lens elements  106   b   6  (detailed in  FIG. 3C ) also makes irradiation system  106   b  more efficient. 
       FIG. 3C  provides a detailed side view of one of lens elements  106   b   6  of  FIG. 3B , where light from the adjacent light producing array  106   b   5  passes through lens element  106   b   6  on the way to target area  106   b   10 . Some of the light goes through the primary (central) lens portion  106   b   6   c , where such light is shown as extending in a vertical direction in the view shown in  FIG. 3C . As shown in  FIG. 3C , the primary (central) lens portion  106   b   6   c  may have a “double convex” profile designed to aim the light to a central region of target area  106   b   10 . The double convex profile means that light enters a first “entry” convex profile of the lens, and is then directed to a second “exit” convex profile of the lens. 
     In addition to the primary (central) lens portion  106   b   6   c  of lens element  106   b   6 , each lens element  106   b   6  includes a first side portion  106   b   6   a  and a second side portion  106   b   6   b . A portion of the light (e.g., illustrated as dotted line  106   b   11  in  FIG. 3C ) from light producing array  106   b   5  also reflects off of the curved side walls  106   b   6   a   1 ,  106   b   6   b   1  of each of the side portions  106   b   6   a ,  106   b   6   b , and exits lens element  106   b   6  via curved walls  106   b   6   a   2 ,  106   b   6   b   2 , on its way to target area  106   b   10 . Specifically, the light that enters curved side walls  106   b   6   a   1 ,  106   b   6   b   1  refracts and then interacts with the total internal reflection (TIR) surface of the curved side walls  106   b   6   a   1 ,  106   b   6   b   1 . 
     As shown in  FIG. 3C , each lens element  106   b   6  is aligned in grooves  106   b   2   a  (or other features) of the respective wall section  106   b   2 , which provides for efficient installation, removal, and alignment.  FIG. 3C  also illustrates a gap  106   b   12  between light producing array  106   b   5  and lens element  106   b   6  (i.e., lens element  106   b   6  is spaced apart from the light producing elements of light producing array  106   b   5 ). This gap  106   b   12  allows for efficient cooling of light producing array  106   b   5 . 
     In accordance with certain exemplary embodiments of the invention, lens elements (e.g., lens elements  106   b   6  shown in  FIGS. 3B-3C ) may be formed from at least one of a quartz material and a silicon based material. 
     In accordance with certain exemplary embodiments of the invention, and in connection with irradiation system  106   b  shown in  FIGS. 3A-3C  (and similar irradiation systems), the lens elements may be positioned in a specific location to optimize light energy provided by the light producing arrays based on predetermined criteria. Such predetermined criteria includes at least one of a target location, a target size, a desired area of irradiation around the target, and a desired level of irradiation of the target. 
     Thus,  FIGS. 3A-3C  illustrate one detailed example of an irradiation system  106   b .  FIGS. 4A-4B  illustrate another detailed example, through the external ( FIG. 4A ) and internal ( FIG. 4B ) views.  FIG. 4A  illustrates a simplified, end view, of an irradition system  106   c  (the elements within the enclosure are removed for simplicity, but see  FIG. 4B ). Irradiation system  106   c  includes a housing  106   c   1  (which may be similar to housing  106   a   1  in  FIG. 2 , or may vary as desired) including a plurality of wall sections  106   c   2 . While illustrated in a simplified manner, each wall section  106   c   2  may represent a more complex structure, for example: (i) an outside wall portion/structure and an interior wall portion/structure (e.g, an interior substrate wall similar to substrate wall  106   a   3  in  FIG. 2 ); or (ii) a part of an underlying housing such as housing  106   a   1  shown in  FIG. 2 , that supports a substrate sections such as substrate wall  106   a   2  in  FIG. 2 . 
     Irradiation system  106   c  includes three (3) light producing arrays  106   c   5  (e.g., LED arrays), which are visible in  FIG. 4B . As shown in  FIG. 4A  (when viewed in connection with  FIG. 4B ), a heatsink  106   c   3  along with a corresponding cooling element  106   c   4  (e.g., a fan), is provided on each of the wall sections  106   c   2  that supports a light producing array  106   c   5  (e.g., an LED array). 
       FIG. 4B  is another end view of irradiation system  106   c , but that shows certain of the internal elements thereof. In the example shown in  FIG. 4B , three (3) light producing arrays  106   c   5  (e.g., LED arrays including a plurality of LED light producing elements) are provided, and are positioned with respect to one another to surround a target area  106   c   10  and a target  106   c   8 . In the example shown in  FIG. 4B , target  106   c   8  (e.g., an optical fiber) is provided in a target housing  106   c   9  (e.g., a quartz tube, as in  FIG. 2 ). A desired optical boundary limitation  106   c   10  (e.g., also referred to as a target area  106   b   10  for receiving a predetermined level, or profile, of irradiation) is also shown around target  106   c   8  and target housing  106   c   9 . 
     Light producing arrays  106   c   5  (e.g., LED arrays) are each provided on internal portions of wall sections  106   c   2 . A primary reflector  106   c   6  is positioned adjacent each of the light producing arrays  106   c   5  (e.g., LED arrays), and is configured to direct light energy from the respective one of the plurality of light producing arrays  106   c   5  toward optical boundary limitation  106   c   10  (and target  106   c   8 ). Optical reflectors  106   c   7  (also referred to herein as secondary reflectors), each including an internal curved surface  106   c   7   a  (e.g., for reflecting light back toward optical boundary limitation  106   c   10  and target  106   c   8 ), are provided between each of primary reflectors  106   c   6 . Light from each light producing array  106   c   5  passes through (and/or is reflected by) a respective primary reflector  106   c   6 , and then on to optical boundary limitation  106   c   10  (and target  106   c   8 ). The inclusion of optical reflectors  106   c   7  between primary reflectors  106   c   6 , makes irradiation system  106   b  more efficient (e.g., because additional light energy is reflected off of curved surface  106   c   7   a , and back toward optical boundary limitation  106   c   10  and target  106   c   8 ). 
       FIG. 5  is a flow diagram illustrating a method of designing an irradiation system for curing a target in accordance with an exemplary embodiment of the invention. As is understood by those skilled in the art, certain steps included in the flow diagram may be omitted; certain additional steps may be added; and the order of the steps may be altered from the order illustrated. 
     At Step  500 , a target configured for curing using the irradiation system is provided. At Step  502 , curing characteristics for curing the target are determined. The curing characteristics include at least one of (i) a desired level of irradiation for curing the target and (ii) a target area for receiving energy from the irradiation system. At Step  504 , the curing characteristics are used to determine a plurality of LED arrays for inclusion in the irradiation system. At Step  506 , the plurality of LED arrays are positioned with respect to one another such that they surround the target area of the irradiation system. 
     Depending on the specific application, additional steps may be included in the method shown in  FIG. 5 . For example, in an application including an irradiation system such as that shown and described with respect to  FIGS. 3A-3C , the method may also include a step of positioning a lens element (e.g., lens elements  106   b   6 ) between each of the LED arrays and the target area. The position of the lens elements may be specified to optimize light energy provided by the LED arrays based on predetermined criteria. Such predetermined criteria includes at least one of a target location, a target size, a desired area of irradiation around the target, and a desired level of irradiation of the target. 
     In another example, in an application including an irradiation system such as that shown and described with respect to  FIGS. 4A-4B , the method may also include the steps of: (i) providing a plurality of primary reflectors, each of the plurality of primary reflectors being configured to direct light energy from a respective one of the plurality of LED arrays toward the target; and providing a plurality of secondary reflectors, each of the plurality of secondary reflectors being positioned between respective ones of the plurality of primary reflectors. 
     A number of significant benefits are achieved through various exemplary embodiments of the invention such as, for example: improved efficiency in managing heat generated by the light producing elements/arrays, which affords extended LED chip lifetime and the ability for shorter wavelength chips (e.g., UVB and UVC) to be used (which require more cooling than UVA chips); a lamp/irradiator designed according to the target that will be cured (e.g., in an optical fiber curing application, a column of fiber can be cured with a column of light); improved photon management, uniformity, and efficiency at the target; improved curing performance with less radiation/energy; because of light producing arrays surrounding the target, there is essentially 360° direct curing to the target; and modularity in that the design can be easily modified by changing the number of elements (e.g., light sources, lenses, etc.). 
     Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.