Abstract:
A tubular luminaire efficiently utilizes the light of a line of high-brightness unlensed LEDs to reproduce the homogeneous appearance of a neon tube. The transparent tube has an annular cross-section suitable for cost-effective manufacturing by extrusion. The LEDs are mounted in a line on a circuit board that can be positioned either inside or outside the tube. Their light shines into a cylindrical groove, thereby entering within the material of the tube. Above the groove, the wall of the tube has a spiral shape that reflects the light laterally so that it stays within the annular tube for a considerable path length. Volume scattering by a low density of scattering inclusions causes the light to escape as a homogenous glow. Alternatively, mild surface scattering from the inside surface can be used.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to illumination and more particularly to LED-based tubular substitutes for the neon lamp. The neon lamp is a venerable and ubiquitous accent light with such technological maturity that no significant improvements are in sight, but with such fragility and high operating voltage (&gt;15,000 V) as to pose inescapable risks. For example, fragility is so high that long-distance shipping is not economical due to inevitable breakage, and thus most lamps are custom-produced locally by small businesses, precluding the economies of mass production. Of societal significance is the relatively low efficacy of neon lamps, leading to excessive power consumption. Furthermore, neon lamps are volume emitters, leading to their perceived brightness being proportional to the length of the viewer&#39;s line of sight through the cylinder. Thus they are highly non-uniform spatially and directionally. 
     Fluorescent tubes have uniform brightness but lack neon&#39;s color purity. 
     LEDs have better efficacy and can generate white light of selectable color temperature, light of higher color purity than fluorescent tubes, or programmably multicolored light, with great improvements in safety, robustness, and operating life as compared with neon technology. Recent gains in the luminosity and operating lifetime of light-emitting diodes (LEDs) make them attractive candidates to replace neon light sources, especially considering their robustness and low operating voltage. The prior art includes numerous ways of end-firing LEDs into long runs of plastic illumination fibers, typically 0.5-1 inch (12 to 25 mm) diameter. This sets rather low limits on the output brightness of the fiber. 
     Relative to the size of neon lamps, however, LEDs are point sources, so that their light must be somehow spread out along a tubular structure so as to reproduce the look of neon. The end-fired cylindrical lights of the prior art, such as U.S. Pat. No. 6,488,397 by Matsutani &amp; Ishiharata are limited in the amount of light that can be injected into them, which limits their length as well, if they are to equal or surpass the luminance of neon lamps. Also, many illumination fibers are made of elastomeric material, so that their lack of rigidity requires frequent support to prevent unsightly sagging. Finally, the diameter of such solid fibers is limited by weight considerations. 
     In the recent prior art, U.S. Pat. No. 7,048,413 by Fan discloses a round scattering layer above a line of bullet-lens LEDs. This approach however, is not a true tube-emitter like neon, since its light shines only out the front part of the device. Also, the bullet-lens LEDs it utilizes represent an older configuration that is optically inefficient and generally of lower efficacy than the more recent high-brightness LED configurations utilized in the present application. U.S. Pat. No. 6,834,979 by Cleaver et al is similar in its approach and limitations. 
     U.S. Pat. No. 6,874,924 by Hulse &amp; Chambers discloses an annular cylindrical structure cut so as to allow side injection of light, again by bullet-lens LEDs, but also including an interior partially reflecting scattering layer. U.S. Pat. No. 6,497,496 by Wang also utilizes a non-waveguiding annular cylinder with radially directed light sources and opposing holes. U.S. Pat. No. 6,676,284 by Wilson also has an annular cylinder, but it is merely a diffusing cover illuminated by a line of centrally located, closely spaced light sources. 
     U.S. Pat. No. 7,277,618 by Yamazaki, et al discloses a conventional optical fiber impregnated with phosphor and end-fired by blue LEDs. Impregnating the waveguide itself with phosphor would make it difficult to attain uniformity of either brightness or whiteness, because blue light is being converted to yellow as it propagates down the fiber, so that its strength weakens and the local fiber emission diminishes and alters color. 
     There is a great need for a superior LED-based neon substitute that can utilize the latest high-brightness LEDs (which are not available in the thermally inefficient bullet lenses mention above). 
     SUMMARY OF THE INVENTION 
     One embodiment of the present invention comprises means to inject light at spaced intervals and means to assure luminance-uniformity, an important requirement when using high-brightness LEDs, since their cost motivates a relatively wide spacing (several tube diameters) between them. This relatively distant spacing is quite unlike the prior art as discussed above, which utilizes a large number of closely spaced low-brightness LEDs, because of their low cost. The cost per lumen of the low-brightness LEDs, however, is much greater than for high-brightness LEDs, hence the need for optics capable of utilizing widely spaced light sources. 
     According to an embodiment of the invention, there is provided a tubular luminaire comprising a line of discrete light sources and a cylindrical transparent annular waveguide. The waveguide comprises a receiving zone, which zone receives the light of the sources so as to admit the light within the transparent material of the annular waveguide. The waveguide comprises an ejector to promote the homogeneous escape of the light from the waveguide. 
     The discrete light sources may be LEDs or other punctuate sources. 
     In an embodiment, the cylindrical transparent annular waveguide has an outer surface that is a right circular cylinder, or an arc of such a cylinder, so that light once reflected by total internal reflection (TIR) within the waveguide will be repeatedly reflected by TIR and will travel around the cylinder until it is ejected by another process. The outer surface may be a complete cylinder, a cylinder complete except for one or more sections specially shaped for injection of light into the waveguide, or a lesser arc. In an embodiment, the cylindrical waveguide is slightly less than a semicircle, with light being injected at one end. An almost complete circular cylinder may then be formed by two such waveguides back to back. 
     Embodiments of the present invention disclose methods of side-firing of unlensed high-brightness LEDs into a tubular annulus. The annulus is typically lighter in weight than a solid tube of the same external diameter, which is advantageous in many uses. Nearly all of the light from a line of LEDs is injected into an annular waveguide. Suitable extraction methods are well known for ejecting this guided light out of the tube. They can be classified as surface or volume scattering. In both cases, not all the scattered light gets immediately out of the tube, since some remains trapped inside the annulus by total internal reflection until again scattered. This helps to smooth out the luminous appearance of the tube as externally viewed, which is advantageous in many uses. In fact, luminous uniformity is often of such high importance that without it no amount of robustness, efficacy, longevity, or low costs will make up for its lack. The human eye is most pleased by luminance uniformity of accent lights, and is intolerant of luminance gradients beyond a fairly low threshold. Embodiments of the present invention make it possible to obtain this uniformity. Moreover, the tubular neon substitute of embodiments of the present invention comprises a hollow rigid tube that will not sag or require great structural support, and can be economically extruded out of a plastic material such as acrylic. 
     In addition to the uniform luminance exhibited by neon tubes, other types of output are possible with further embodiments of the present invention. The small size of LEDs relative to a tubular embodiment makes it possible for collimated light to be produced by coordinated specular ejection, which preserves the LED&#39;s luminance. Diffuse ejection, used by some preferred embodiments, precludes such collimation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
         FIG. 1  shows a cross-section of an embodiment of an inside-fired annular waveguide. 
         FIG. 2  shows a cross-section of another embodiment of an inside-fired annular waveguide with a greater relative wall thickness than in  FIG. 1 , for ease of extrusion. 
         FIG. 3  shows a cross-section of an outside-fired annular waveguide with a minimum radius, relative to wall thickness. 
         FIG. 4  shows a cross-section of an alternative injector configuration with greater minimum thickness than  FIG. 3 . 
         FIG. 4A  is a detail of  FIG. 4 , to a larger scale than  FIG. 4 . 
         FIG. 5  shows a cross-section of an outside-fired annular waveguide for undomed LEDs. 
         FIG. 5A  is a detail of  FIG. 5 , to a larger scale than  FIG. 5 . 
         FIG. 5B  is a sectioned perspective view of the waveguide shown in  FIG. 5 . 
         FIG. 6  shows a dual-source configuration. 
         FIG. 7  shows a luminance transporter. 
         FIG. 8  shows a tapering annular waveguide. 
         FIG. 9  shows two of the waveguide shown in  FIG. 8  combined into a single source. 
         FIG. 10  shows a similar configuration to  FIG. 9 . 
         FIG. 11  shows a configuration with an external phosphor cladding. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Corresponding reference characters indicate corresponding components throughout the several views of the drawings. 
       FIG. 1  shows a cross-section of and embodiment of a tubular luminaire indicated generally by the reference numeral  10 . Luminaire  10  comprises transparent hollow tube  11 , circuit board  12 , LED package  13 , LED emitter chip  14 , and transparent LED dome  15 . Transparent hollow tube  11  comprises circular groove  16  surrounding dome  15 , and injector section  17 , bounded by upper spiral surface  17   s  and a lower flat surface  17   f . Also shown are some exemplary light rays emitted from the edge of chip  14 . All light from chip  14  remains trapped within the wall of tube  11  by total internal reflection, until scattered out by either or both of two mechanisms, weak volume scattering or graded surface scattering. Light from the LEDs undergoes a high number of reflections per average path length. When using surface scattering for ejection, more reflections mean scattering sooner, with a greater chance for circumferential nonuniformity. 
     The interior space of tube  11  is hollow and typically simply contains air. If cooling for the LED chips  14  is desired, a fan or other air-moving device may be used to circulate cooling air along the interior space. 
       FIG. 2  shows another embodiment of a tubular luminaire  20 , comprising transparent hollow tube  21 , internally positioned circuit board  22 , LED package  23  mounted thereupon, and LED emitter chip  24  inside transparent LED dome  25 . Hollow tube  21  is formed with circular groove  26  matching dome  25 , and upper spiral surface  21   s  above groove  26 . Tube  21  has the maximum thickness as expressed by inner radius rI and outer radius rO such that
 
 rI/rO =sin α
 
where α is the minimum incidence angle, required to be greater than the critical angle of the transparent tube material. A 45° value is shown in  FIG. 2 . This assures that the light will remain within the tube as it propagates away from the LEDs before being scattered out. With the thinner tubes, some of the light will reflect off the inner wall by TIR is never perfect, and some light rays could be scattered outwards and refracted by the outer wall, and become visible to the viewer as a glowing inner wall, magnified by the curvature of the outer wall. The proper ratio of inner to outer diameter will make that magnified image just fill the apparent outer surface, so that the glowing inner wall is not separately distinguishable.
 
     Thicker walls are easier to make, but heavier. In most cases, the thickness shown in  FIG. 2 , in which critical angle rays  27  are tangent to the inner wall, is the maximum desirable thickness. This is precisely the condition of all light from the inner wall escaping through the outer wall. 
       FIG. 3  shows tubular luminaire  30 , comprising transparent hollow tube  31 , externally positioned circuit board  32 , LED package  33  thereupon, LED emitter chip  34 , transparent LED dome  35 , circular groove  36  matching dome  35 , and inner spiral surface  31   s  above groove  36 . The embodiment  30  of  FIG. 3  is substantially the same as the embodiment of  FIG. 2  except for having the LED assembly  32 ,  33 ,  34 ,  35  on the outside and the spiral surface  31   s  on the inside. The embodiment of  FIG. 3  has the advantage that the LED assemblies are easily accessible for assembly, power supply, and maintenance, but the embodiment of  FIG. 2  has the advantage that the light emission is uninterrupted round the entire circumference of the tube  21 . Internally illuminated embodiments such as that of  FIG. 1  may be made up to a few feet (a meter or two) long, and may be used as accent lights. For greater lengths, it becomes increasingly difficult to insert the circuit board  12 ,  22  into the tube, and the externally illuminated embodiments may be preferred where a long continuous tube is desired. 
     The circuit board  32  may serve as, or may be attached to, a mount for mounting the luminaire  30  on a wall or other surface of an architectural structure. 
     The domed LEDs shown so far represent a common type, such as those commercially available from the Lumileds Corporation having a 5 mm dome-diameter. This size sets the scale for the entire luminaire. If the domes  15 ,  25 ,  35  have a 5 mm diameter, the tubes of  FIG. 2  and  FIG. 3  thus have an outer diameter of about 1.5″ 38 mm, which is larger than most neon tubes. 
     One problem with the configuration of  FIGS. 1 to 3  is the lack of material between circular groove  16 ,  26 ,  36  and the central cusp of spiral surface  21   s ,  31   s , causing tube  31  to lack full rigidity.  FIGS. 4 and 4A  show a cross-section of a further embodiment of a tubular luminaire  40 , comprising transparent hollow tube  41 , externally positioned circuit board  42 , LED package  43  thereupon, LED emitter chip  44 , transparent LED dome  45 , groove  46  matching dome  45 , and inner spiral surface  41   s  above groove  46 . Luminaire  40  has an appreciable thickness of material between the groove  46  and the cusp  41   t  of spiral surface  41   s . As is best seen in the detail view in  FIG. 4A , groove  46  has a V-top that causes light to miss the tip or cusp  41   t  between the spiral surfaces  41   s , which cannot actually be manufactured without some fillet radius that would allow light to escape. Thickness  47  between the tip  41   t  and the V-top of groove  46  enables the tube material to form a single uninterrupted and rigid piece. Unfortunately, this also scales up the entire device, so that, if using the same 5 mm diameter LED domes mentioned above, the outer diameter of tube  41  has grown to two inches (50 mm), well outside the normal range of neon tubes. 
     In order to reduce device diameter to the half-inch (12 mm) range typical of neon tubes, a different LED may be used, one without a dome, so that the spiral injector can be smaller and closer to the LED.  FIG. 5  and detail  FIG. 5A  show a cross-section through tubular luminaire  50 , comprising transparent hollow tube  51 , externally positioned circuit board  52 , flat-top LED package  53  thereupon, LED top-emitting chip  54  optically coupled to the flat bottom of tube  51 , with inner spiral surface  51   s  above it. The outer diameter of tube  51  is about half an inch (12 mm). 
     Regarding the neon-substituting light-emission that is a raison d′être of certain embodiments of the present invention,  FIGS. 5 ,  5 A, and  FIG. 5B  show exemplary ray  55  proceeding from emitting chip  54 , bouncing numerous times in typical waveguide fashion, unable to break the radial symmetry of the annulus and escape (unless it should happen to encounter spiral  51   s , after going all the way around tube  51 ). As mentioned above, light emission may be produced by an ejector scattering some of the rays. At exemplary scattering point  56 , escaping ray  57  represents the half (approximately) that are scattered out, and trapped ray  58  the other half. If the concentration of scattering points  56  is uniform, a high rate of scattering will increase the proportion of rays that are scattered out, at the expense of uniformity, with areas near the LEDs  54  typically being brighter than areas on the opposite side of the tube  51 . A low rate of scattering will give higher uniformity, but many rays will complete the circuit and return to spiral  51   s  and LED package  53 ,  54 . Such returning rays may either be absorbed, reducing efficiency, or escape through spiral  51   s , producing a bright streak. 
     It is possible for the extrusion process to create low volume-scattering near the line of LEDs, but increase the volume-scattering progressively in a circumferential direction to a maximum on the opposite side, to ensure that most of the light is scattered out before getting all the way around, while at the same time producing the homogeneity in the apparent brightness of the tube that is one of the desirable features of many embodiments of the present invention. 
       FIG. 5B  shows a line of LEDs  53  spaced along the length of the luminaire  50 , and shows how rays  55  propagating obliquely to the principal axes of the tube  51  can spread the light evenly over the length, as well as the circumference, of the tube. It will be understood that the other embodiments will typically have a similar arrangement along the length, although in most cases only a single cross-section perpendicular to the length of the tube is shown and, in the interests of clarity, exemplary rays in the plane of the drawing are shown. 
     Another method of producing uniform emission is an ejector in the form of a gradation of nanometer-scale surface roughening on either or both surfaces. This is more difficult to accomplish with extrusion, but might be worth the expense in some cases. Totally internally reflecting light, as in the tubular waveguide of the present invention, is especially sensitive to nanometer-scale roughness, which does not affect transmitted light, however. 
     It is possible to further augment the tubular luminaire with a second line of light sources and a second set of injection means.  FIG. 6  shows tubular luminaire  60 , comprising transparent hollow tube  61 , internally positioned circuit board  62 , LED package  63  mounted thereupon, LED emitter chip  64  inside transparent LED dome  65 , circular groove  66  matching dome  65 , and upper spiral surface  61   s  above groove  66 , as well as lower circuit board  62 L, lower LED package  63 L mounted thereupon, second LED emitter chip  64 L inside transparent LED dome  65 L, lower circular groove  66 L matching dome  65 L, and lowermost spiral surface  61 L below groove  66 L. Assuming the spacing of LED packages  63  and the spacing of LED packages  63 L are equal to the spacing of LED packages  23 , and the two embodiments  20  and  60  are otherwise identical, this doubles the amount of light within waveguide  61  compared with waveguide  21 . That augmentation is usually better suited to the internally illuminated luminaires  20 ,  60  than to luminaires  10 ,  30 ,  40 ,  50  because having two externally positioned circuit boards would obstruct a significant part of the exterior of the tubular luminaire. 
     It is possible to inject light tangentially into an annular waveguide in such a way that all light remains within the waveguide unless some ejector acts upon it. Such a waveguide is also known as an angle rotator.  FIG. 7  shows angle rotator  700  with acceptance and exit angle  701 , such that light entering the rotator within the angle  701  of the normal to the entry face will remain guided within the interior of the rotator  700 . The rotator  700  rotates light by an angle  707 . Light enters the optic on the left confined by a flat mirror  704  and a macrofocal parabola  703  on one (inner) side and a macrofocal parabola  702  on the other side, both with macrofocus  712 . Between section lines  708  and  709 , light is confined by circular arcs  704  and  705 , both with center  706 . The injection of light into this section by macrofocal parabolas  702  and  703  is such that edge rays are reflected at the outer surface  705  with angle  710  and at the inner surface  704  with angle  711 . Rotation angle  707  for end-injected light can be chosen freely by extending circular arcs  704  and  705 . 
     If it is not desired to have light emitted from the whole circumference of the luminaire, part of the transparent hollow tube could be formed as an angle rotator  700 . For example, if the luminaire will be viewed only from a narrow angle, so that one side (the “back” side) will never be seen by viewers, it may be more efficient to mount the LEDs at the back, and use angle rotators to conduct the light to the point, less than 90° from the LEDs, by an amount depending on the viewing angle, where the surface of the luminaire becomes visible and useful ejection of radiation starts. 
       FIG. 8  shows a tapering annular waveguide  800  with ejection features. Hemispheric light is emitted by source  801  and propagates across narrow air gap  802 , encountering end wall  803 , which refracts the light so it is confined within the critical angle a and will remain guided within the waveguide. Macrofocal parabola  804  then redirects the edge rays into the remaining part of the light guide to the right of section line  811 . To the right of section line  811 , light is confined on the outside by circular arc  808  with center  810 , and on the inside by inner flow lines  809  (also circular with center  810 ) and ejectors in the form of extraction features  812 . The angle with which the edge rays hit outer surface  808  is the critical angle α=sin −1 (1/n) of the material of the light guide. This angle corresponds to angle  701  in  FIG. 7 . Extraction features  812  are designed so that exemplary ray  805  that has been reflected at the critical angle a at the outer surface  808  is reflected at  812  in a direction  806  such that, after refraction at the outer surface  808 , the light comes out in a given direction  807 . The result of this is that light refracted at surface  808  comes out confined by direction  807  and the tangent to  808 . Although in this example there is an air gap  802  between the source  801  and the light guide, similar devices can be designed, using the general principles of nonimaging optics, without such an air gap. 
       FIG. 9  shows two light guides such as that of  FIG. 8  combined into a single light-emitting tube  900 . The resulting emission pattern is such that light exiting the tube is limited angularly by direction  91  and the tangent to the tube and by direction  92  and the tangent to the tube. As shown in  FIG. 9 , the end of angle rotator  700  and the first extraction feature  812  are positioned so that the limiting rays  91 ,  92  from the first extraction feature on each side form an angle of approximately 180°, within which the overall light emission of the tube  900  is confined. Subsequent extraction features  812  are more prominently shaped, so that the limiting ray from each subsequent extraction feature  812  is parallel to rays  91 ,  92  and at a greater angle to the local tangent. There are two light sources  93  and  94 , one on each side. The tip edges of the two waveguides  800  may be joined together for rigidity and structural strength. 
       FIG. 10  shows an optic  100  comprising annular tube  103  similar to that in  FIG. 9  but in which the angle rotator section  700  is longer than angle rotator section  804  in  FIG. 8 , and light emission is now confined by symmetric directions  101  and  102  making an angle of approximately 90° to each other. Just as before, at each point on the exit surface of the optic  103 , light emission is confined between direction  101  and the tangent to that surface. 
     In fiber optic devices there is an outer lower-index layer called the cladding, a feature that can be utilized for the present invention. Especially suitable for this role are fluoropolymer species, including PTFE (Polytetrafluoroethylene), FEP (Fluorinated ethylenepropylene), PFA (Perfluoroalkoxy), ETFE (Ethylene tetrafluoroethylene). They appear as clear to milky white color in their natural, unpigmented state. The clearest fluoropolymer resin is PFA HP, which allows for a high level of light transmission. FEP is quite clear as well, while PTFE material tends to be more milky in color. Levels of clarity can be modified to some extent by different processing methods and through the use of a variety of resin grades. Numerous fillers are available to alter mechanical or chemical properties, including photoluminescent phosphors. If the LEDs of the presently described devices are blue, a phosphor cladding that converts some of the blue light to emit yellow light may be used. With the proper thickness and density, such a phosphor cladding would produce white light. Alternatively, a line of ultraviolet LEDs could operate in conjunction with the same type of white phosphor as in conventional fluorescent lamps. 
     The main annular waveguide tube  103 , like the annular waveguides in the other embodiments, may be made of any suitable transparent material, including flexible plastic materials already known for fiber optic illuminators. These materials include flexible acrylics, as well as vinyl. It is well known to materials science how to alter acrylic formulations so as to confer flexibility sufficient for the cross-sections of the Figures to follow space curves, such as draped around a Christmas tree. The art of fiber optic illumination also includes transparent plastics of lower refractive index used as cladding. Vinyls and silicones offer numerous candidates for this role. It will be understood by a skilled practitioner of the art of fiber optic illumination how to use flexible materials, and to include a cladding, on any of the preferred embodiments the cross-sections of which are disclosed herein. 
       FIG. 11  shows luminaire  110 , comprising transparent annular cylindrical waveguide  111  with spiral reflector section  111   s , LED with base  112 , package  113 , emitting chip  114 , and dome  115 . On the profile of waveguide  111  is circular section  116  for receiving light from dome  115 . Atop waveguide  111  is phosphor-impregnated cladding layer  117 , covering the top half of waveguide  111  and emitting converted light in all directions. By covering only half of waveguide  111  the emission of cladding  117  is biased upwards. 
     The line of LEDs of the present invention are suitable for the usual temporal controls long known in the lighting industry, controls that were pioneered in Las Vegas in the 1950&#39;s with incandescent lights. In the case of LEDs, however, electronics replace the old rotary switches. For example, the line of LEDs of the present invention can be controlled by DMX (Digital MultipleX, a practice from the 1980&#39;s which became a standard in 1990. Its current 2004 standard is incorporated as a reference and listed as such. 
     The LEDs of the present invention can as well be controlled by a variety of electronic signal protocols, particularly Ethernet, DALI, TCP/IP, HTTP, XML, Bluetooth, and 802.11 wireless. 
     It has long been known that LEDs can have their overall flux controlled by pulse-code modulation (PCM) or pulse-width modulation (PWM), originally established in the 1970&#39;s by the inventors of the LED themselves. Numerous applications of this technique have been taught in the prior art. PWM makes it possible in the present devices to control individual LEDs to generate pleasing traveling-wave patterns as well as static or slowly changing color of the entire length of an accent light, by the use of RGB or RBGY multiple-wavelength lamps. 
     Certain embodiments of the present devices differ from the prior art, however, in that the mixing of the LED light by the ejector of the annular configuration makes possible colorimetric gradients along the tube, between two lamps of different colors, that would be more pleasing to the human eye than anything attainable in the prior art. Luminaires with independently controllable light sources, including light sources of different colors, and including luminaires provided with, or equipped to cooperate with, electronic control systems to produce these or other lighting effects, are within the scope of the present invention as defined in the claims of the present application. 
     Luminaires in accordance with embodiments of the present invention are of course suitable for customized lettering and symbology, as is already done with neon tubes. The lettering may be formed by curved tubes, straight tubes, or successive curved and straight runs. The tubes may be flexible, or may be rigid and preformed to a desired shape, or may be softenable or plasticly deformable but then hold their shape rigidly in normal use. Commercially available flexible LED connectors can take the place of the circuit boards  52  in such a configuration, especially in curved runs or continuous sections of tube that include curved runs. This long-established and open prior art is claimed by the present invention solely as used with the annular tube configurations disclosed herein. As with the linear configurations mentioned above, the degree of homogenization attained by the present invention enables the creation of pleasing multicolor displays along the length of the annular tubing of the present invention forming a particular emblem or symbol. 
     In the foregoing description, terms of relative position such as “top” and “bottom” have been used for convenience with reference to the positions of features shown in the drawings. The devices shown are not required to be installed or operated in those specific orientations, and the positional language is not to be understood as limiting. 
     Although specific embodiments have been described, the skilled reader will understand how features of different embodiments may be combined and substituted, and such combinations are within the scope of the present invention. 
     For example, the flat-topped LED package  52 ,  53 ,  54  shown in  FIGS. 5 and 5A  can be used in the luminaires shown in  FIGS. 1 ,  2 ,  3 ,  4 ,  6 , and  11 . For example, the added wall thickness  47  shown in  FIG. 4A  can be used in the luminaires shown in  FIGS. 1 ,  2 ,  3 ,  6 , and  11 . The skilled reader will understand how to make the appropriate consequential changes to each embodiment to enjoy the advantages of those additional features. 
     The following U.S. PATENT DOCUMENTS are herein incorporated by reference in their entirety: 
     
       
         
               
               
               
             
           
               
                   
               
             
             
               
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                 315/209 
               
               
                 2006/0,193,357 
                 Pruett 
                   372/38.07 
               
               
                   
               
             
          
         
       
     
     The following other document is herein incorporated by reference in its entirety: 
     ESTA Publication,  Entertainment Technology—USITT DMX 512- A—Asynchronous Serial Digital Data Transmission Standard for Controlling Lighting Equipment and Accessories,  American National Standards Institute, 2004 
     The preceding description of the presently contemplated best mode of practicing the invention is not to be taken in a limiting sense, but is made merely for the purpose of describing certain general principles of the invention. The full scope of the invention should be determined with reference to the Claims.