Abstract:
An apparatus including a diffuser defining an enclosed area within an interior of the diffuser; a solid state light source, disposed within the interior of the diffuser, emitting light therefrom in a direction away from a horizontal plane containing the solid state light source; optics disposed within the interior of the diffuser adjacent to and above the solid state light source to reflect, utilizing total internal reflection (TIR) and refractive mechanisms, at least a portion of the light emitted from the solid state light source.

Description:
RELATED APPLICATION 
       [0001]    This application is a non-provisional of, and claims benefit under 35 USC 119 of, co-pending, commonly owned provisional application 62/051623, filed 17 Sep. 2014, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    Many tubular-shaped fluorescent lamps are known. Their omni-directional light distribution is favored by many people. Solid state light sources are increasingly being used to replace fluorescent lamps. However, solid state light sources typically project light in a relatively directional manner. While replacement for fluorescent lamps have been previously proposed, the light therefrom may typically produce lambertian photometry that may not be desired for some applications. 
         [0003]    Therefore, it would be desirable to provide improved methods and apparatus for providing a replacement lamp having a solid state light source that substantially provides a light distribution efficient for different applications. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    Features and advantages of some embodiments of the present invention, and the manner in which the same are accomplished, will become more readily apparent upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0005]      FIG. 1  is an illustrative cross-sectional view of a tube lamp having a LED light engine; 
           [0006]      FIG. 2  is an optical distribution chart, corresponding to the lamp of  FIG. 1 ; 
           [0007]      FIG. 3  is an illustrative cross-sectional view of a tube lamp having internal optics, in accordance with some embodiments herein; 
           [0008]      FIG. 4  is an optical distribution chart, corresponding to the lamp of  FIG. 3 ; 
           [0009]      FIG. 5  is a side elevation view of a lamp, according to some embodiments herein; 
           [0010]      FIG. 6  is a perspective view of a portion of a TIR lens for a lamp, in accordance with some embodiments herein; 
           [0011]      FIG. 7  is a detailed perspective view of a portion of a lamp, in accordance with some embodiments herein; 
           [0012]      FIGS. 8 and 9  are optical distribution charts for lamps with different tube diffusers, according to some embodiments herein; 
           [0013]      FIG. 10  is a detailed cross-sectional view of a tube lamp having internal optics, according to one embodiment herein; 
           [0014]      FIG. 11  is a cross-sectional view of a tube lamp having internal optics, according to some embodiments herein; 
           [0015]      FIG. 12  is a perspective view of the tube lamp of  FIG. 11 , according to some embodiments herein; 
           [0016]      FIGS. 13 and 14  are optical distribution charts for the  FIG. 11  lamp with different tube diffusers, according to some embodiments herein; 
           [0017]      FIG. 15  is a detailed cross-sectional view of the tube lamp of  FIG. 11 , according to some embodiments herein; 
           [0018]      FIG. 16  is an optical distribution chart for a lamp of some embodiments herein; 
           [0019]      FIGS. 17 and 18  are plan views of an environment for an application of the lamps of some embodiments herein; 
           [0020]      FIG. 19  is a tabular listing of observed results corresponding to some lamps, in accordance with some embodiments herein; and 
           [0021]      FIGS. 20 and 21  are a graphical presentations of some of the observed results disclosed in the table of  FIG. 19 . 
       
    
    
     DETAILED DESCRIPTION 
       [0022]      FIG. 1  is an illustrative diagram of a cross-sectional view of a conventional LED tube lamp  100 . The lamp shown in  FIG. 1  may be designated as a replacement of a T8 fluorescent lamp based on its construction and configuration, as understood by those knowledgeable and skilled in the art of lighting. Lamp  100  is an illustrative depiction of a known replacement fluorescent tube lamp. Lamp  100  includes a tube-shape diffuser  110 , a light emitting diode (LED) light source  105  that is connected to a printed circuit board (PCB)  115 . PCB  115  is supported by a heat dissipating structure or heat sink  120 . LED  110 , PCB  115 , and heat sink  120  are located against an interior surface of diffuser wall  110  in a lower or bottom portion of the lamp, given the orientation of lamp  100 . 
         [0023]    Light from LED  105  may typically be distributed in a pattern as depicted in the distribution chart  200  of  FIG. 2 . In particular, the light from LED  105  generally travels in straight paths toward diffuser wall  110 , exits, and distributes in, roughly, a lambertian pattern. In some aspects, a LED T8 replacement lamp with Lambertian photometry is not an efficient solution for some applications. This may be due to the produced light distribution having light in an area where it is not needed/desired, not being uniform on the horizontal plane including the light source, and, for example, not providing enough light for higher shelves in some applications. 
         [0024]    The light distribution of lamp  100  as depicted in  FIG. 2  may be acceptable and even desired in some contexts and use-cases. However, different applications and use-cases may warrant different light distributions where, for example, the light output by a lamp is distributed in specific, desired direction(s) that are efficient for a given application. 
         [0025]      FIG. 3  is a cross-sectional view of a tube lamp  300  having internal optics, according to some embodiments herein. Lamp  300  includes a solid state light source  305  (e.g., a LED or LED array), a tubular-shape diffuser  310 , a PCB  315  supporting the LED array and providing electrical connections to an electrical energy source for energizing the LEDs of the LED array, and a heat sink  320  in thermal communication with PCB  315 . As oriented, LED  305 , PCB  315 , and heat sink  320  are positioned at or near the bottom of the interior of diffuser  310 . Lamp  300  further includes an optics mechanism  325 . Optics mechanism  325 , in some embodiments, is a linear extrusion lens incorporating total internal reflection (TIR) and refractive mechanisms disposed within diffuser  310 . In some aspects, the combination of the TIR lens  325  and the diffuser  310  cooperate to produce or provide a particular, designed light distribution output. In some embodiments, a particular (i.e., predetermined) desired photometry may be achieved by virtue of and based on the combination of a customized linear extrusion lens incorporating TIR and refractive (i.e., multiple) mechanisms, and a diffuser of particular material compositions having particular reflection and/or refraction characteristics. 
         [0026]    In some aspects, optics mechanism  325  shown in  FIG. 3  may generally be described as including two protrusions on a distal side of LED  305 . Each of the two protrusions has, roughly, a triangular cross-sectional shape, as depicted in  FIG. 3 . 
         [0027]      FIG. 4  is an illustrative depiction of the light distribution chart  400  for the LED T8 lamp of  FIG. 3  having the TIR lens  325  incorporating TIR and refractive (i.e., multiple) mechanisms and a clear diffuser tube  310 . In some aspects, diffuser tube  310  (like other diffuser tubes herein unless specifically stated as being otherwise) may be constructed of glass, an extruded polycarbonate, and other materials. By using a TIR lens as disclosed herein, the light emitted from LED light source  305  may be refracted or reflected by TIR lens  325  instead of passing directly though tube diffuser  310 . TIR lens  325  may bend the produced light to different angles. Designing the certain TIR lens(es) herein and adjusting the diffusion of tube(s) herein may result in the desired photometry. For example, embodiments may use a TIR lens that bends the output light to higher angles with a relatively weak diffusion material for tube. With such lamps, some of the centrally produced light may be distributed at a higher angle as shown in the light distribution chart  400  of  FIG. 4 .  FIG. 4  shows a representation of a bat-wing photometry instead of Lambertian. In some embodiments, the angle(s) for bat-wings and narrowness (i.e., width) of the produced photometry may be changed by changing the TIR design and diffuser tube composition materials depending, at least in part, on the desired application. These combination(s) of changes may help to increase an application efficiency for the end-users of the lamps herein. For example, a bat-wing distribution may be a desired photometry in an office environment and a retail area where such a photometry may provide uniform light intensity on a work plane and more vertical foot-candles, Fc, on shelves of the retail space. In some embodiments, a narrow bat-wing will provide more Fc on horizontal plane(s). 
         [0028]      FIG. 5  is an illustrative depiction of a diffuser tube  500 , according to some embodiments herein. The diffuser tube may be constructed of various materials, including but not limited to glass, ceramics, polycarbonates, and other man-made and naturally occurring compositions. These and other materials may be manufactured and/or shaped into the configuration of diffuser tube by a variety of manufacturing techniques and processes, including moldings, extracting, casting, etc. Diffuser  500  may be produced to have dimensions similar to (pre)existing light fixtures and/or light fixture installations. In some embodiments, diffuser  500  may have a diameter and length similar to a “T8” lamp. 
         [0029]      FIG. 6  is an illustrative depiction of a TIR lens (i.e., optics)  600  incorporating TIR and refractive (i.e., multiple) mechanisms that may be disposed within a diffuser tube herein. TIR lens  600  may be constructed of materials and configured into a shape that will, when it is disposed within and used in combination with a diffuser tube herein (e.g., diffuser tube  500 ), produces a desired, predetermined light distribution. 
         [0030]      FIG. 7  is an illustrative depiction of a lamp  700  having a TIR lens  705  incorporating TIR and refractive (i.e., multiple) mechanisms disposed within a diffuser tube  710 . The TIR lens is disposed above an array of LEDs (one LED shown in  FIG. 7  though not labeled with a reference number for sake of clarity of the drawing) and shapes the light rays therefrom based on the characteristics thereof (e.g., construction materials, shape of the lens, dimension of the lens, distance between TIR lens and LEDs, distance between the TIR lens and the diffuser tube, etc.). 
         [0031]      FIGS. 8 and 9  are optical distribution charts for lamps with different tube diffusers, according to some embodiments herein. In a present example, the lamp may generally correspond to the lamp of  FIGS. 3 and 7 .  FIG. 8  is a representation of the light distribution with the LED T8 lamp of  FIGS. 3 and 7  having a clear diffuser tube and  FIG. 9  is a representation of the light distribution obtained with the LED T8 lamp of  FIGS. 3 and 7  having a relatively weak diffusing tube. 
         [0032]      FIG. 10  is a detailed cross-sectional view of a tube lamp  1000  having internal optics  1025 , according to one embodiment herein. In this embodiment, LED T8 lamp  1000  includes TIR lens  1025  incorporating TIR and refractive (i.e., multiple) mechanisms disposed within diffuser  1010  and above LED  1005 . LED  1005  is supported by PCB  1015  where a heat sink/support structure  1020  further supports and dissipates heat from the PCB. The extruded TIR lens  1025  of this embodiment is inside LED T8 Tube and may be designed for a particular application or use-case. TIR lens  1025  may generally be viewed as an optic incorporating multiple optical mechanisms and/or manipulating surfaces within a unitary component that may have, for example, two or more divisions or portions for controlling the light that is incident thereto. For example, TIR lens  1025  is designed to use refraction for the light emitted from LED from about zero degrees to 45 degrees (e.g., light rays  1027 ) and to use total internal reflection for light rays above about 45 degrees (e.g., light rays  1029 ). TIR lens  1025  is designed to direct both of these portions of the light from LED  1005  to about 20 degrees—about 30 degrees, per a particular embodiment application. Like the optics  325  of  FIG. 3 , TIR lens  1025  shown in  FIG. 10  may generally be described as including two protrusions on a distal side of LED  1005 . Each of the two protrusions has, roughly, a triangular cross-sectional shape, as depicted in  FIG. 10 . 
         [0033]      FIG. 11  is a cross-sectional view of a LED T8 lamp  1100  having internal optics  1115  and a LED (or other solid state) light source engine  1005  disposed within a diffuser tube  1110 , according to some embodiments herein. The configuration of TIR lens  1105  incorporates TIR and refractive (i.e., multiple) mechanisms and may be designed to produce a particular, desired photometry. In some aspects, optics mechanism  1115  shown in  FIG. 11  may generally be described as including two protrusions on a distal side of LED  1105 . Each of the two protrusions has, roughly, an inverted triangular cross-sectional shape where the inverted triangular protrusions are joined together by a linear center portion above LED  1005 , as depicted in  FIG. 11 . 
         [0034]      FIG. 12  is a perspective view of the LED T8 tube lamp of  FIG. 11 , according to some embodiments herein.  FIG. 12  shows diffuser tube  1205  housing TIR lens  1210  and other components. The other components are not separately referenced for sake of clarity of the drawing. 
         [0035]      FIGS. 13 and 14  are representative optical distribution charts for lamp  1100  of  FIG. 11 , with different tube diffusers, according to some embodiments herein.  FIG. 13  is a representative light distribution chart  1300  for the LED T8 lamp  1100  having the shown TIR lens and a clear diffuser tube.  FIG. 14  is a representative light distribution chart  1400  for the LED T8 lamp  1100  having the shown TIR lens and a relatively weak diffusing tube. 
         [0036]      FIG. 15  is a detailed cross-sectional view of the tube lamp of  FIGS. 11 and 12 , according to some embodiments herein.  FIG. 15  is a detailed cross-sectional view of a tube lamp  1500  having internal optics  1515 , according to one embodiment herein. In this embodiment, LED T8 lamp  1500  includes TIR lens  1515  disposed within diffuser  1510  and above LED  1505 . LED  1505  is supported by a PCB where a heat sink/support structure further supports and dissipates heat from the PCB. The extruded TIR lens  1515  of this embodiment is inside LED T8 Tube and may be designed for a particular application or use-case. TIR lens  1515  may generally be viewed as an optic incorporating multiple optical mechanisms and/or manipulating surfaces within a unitary component having two divisions or portions for controlling the light that is incident thereto. For example, TIR lens  1515  is designed to use refraction for the light emitted from the LED from about zero degrees to 45 degrees (e.g., light rays  1525 ) and to use total internal reflection for light rays above about 45 degrees (e.g., light rays  1520 ). TIR lens  1515  is designed to collimate the light output from LED, as shown in  FIG. 15 . Similar to  FIG. 11 , optics mechanism  1515  shown in  FIG. 15  may generally be described as including two protrusions on a distal side of LED  1505 . Each of the two protrusions has, roughly, an inverted triangular cross-sectional shape where the inverted triangular protrusions are joined together by a linear center portion above LED  1505 , as depicted in  FIG. 15 . 
         [0037]      FIG. 16  is an optical distribution chart  1600  for a lamp of some embodiments herein.  FIG. 16  illustrates the photometry that is produced by the TIR lens inside the LED T8 lamp of, for example,  FIG. 15 . This TIR directs light to about 10 degrees both sides of the zero degree reference. 
         [0038]      FIGS. 17 and 18  are plan views of an environment for an application of the lamps of some embodiments herein. In particular,  FIG. 17  is a plan view of a room  1700  such as a warehouse having multiple shelves  1705  and  1710 . In between the shelves and mounted to the ceiling of the room are light fixtures (e.g.,  1715  and  1720 ) in accordance with some embodiments herein. The light fixtures have a TIR lens internal to the LED T8 lamp thereof and a diffuser tube that cooperates to provide light in a distribution pattern that is particularly designed to illuminate the face of the shelves that may hold various items.  FIG. 18  is an overhead view  1800  of room  1700  or the like and includes shelves  1805  and  1810  with a lamp  1815  mounted to the ceiling of the room in between the shelves. The room shown in  FIG. 18  includes additional shelves and light fixtures. 
         [0039]      FIG. 19  is a summary table of photometric results obtained in a simulation of the described embodiments. The baseline is a standard T8 lamp (denoted as “LED T8 Regular” in  FIG. 19 ) and is compared to a lamp incorporating the optics described herein (denoted “LED T8 w/Optics” in  FIG. 19 ). Each of these lamps were placed in shelving areas similar to the applications herein. The “Floor Avg.” column depicts horizontal illumination in foot-candles (fc) for the plane directly below the lamps. By incorporating the disclosed optics and subsequently narrowing the output of the lamp, the horizontal illuminance increases from 28.7 fc to 53.7 fc. This represents a large increase in application efficiency for the same given output. Simulated readings across the entire plane are seen to show the same consistency, as described by the ratio of “Floor Avg/Min and “Floor Avg/Max” illuminance. In short, the light levels observed on the floor can be described as substantially higher (desirable) for the same output. The vertical illuminance (“Vertical Avg.”) shows a very similar result. Vertical illuminance corresponds to light levels in a vertical plane lying on the face of the shelves. Simulated across the face of the shelves, vertical illuminance was found to increase from 24.2 fc to 33.4 fc. The consistency of the light level (Vertical avg/min, Vertical avg/max) has been drastically reduced, implied by the lower ratios. Essentially the dim areas of the shelves are better illuminated with respect to the average illuminance seen across the entire shelving unit. 
         [0040]      FIG. 20  is a map of vertical illuminance values as simulated for a standard output T8 without incorporating the optics disclosed herein (i.e., baseline). Here, the black boxes  2005  would be the lamps pointing downward from the ceiling (right in the figure). The ground or floor would correspond to the  2010  at the far right. Isolines depicting the 50, 45,40,25,20, and 15 foot-candle levels are drawn, ranging from around 5 feet (50 FC) to about 2 feet (15FC) from the ground. Observed levels are seen to decrease further down the shelf face as the light approaches the ground. This entire map may be used to calculate the vertical illuminance values displayed in  FIG. 19 . 
         [0041]      FIG. 21  is a map of vertical illuminance values for a similar simulation as represented in  FIG. 20  but incorporating the optics disclosed herein (e.g., a LED T8 lamp with the disclosed optics). Isolines are shown for the 45, 40, 35, 30, and 25 FC light levels. Similarly, these range from around 2 feet to about 5 feet from the ground. 
         [0042]    Together,  FIGS. 20 and 21  illustrate, at least in part, some aspects of the utility of including the optics herein in, for example, a LED T8. In the baseline case, a sharp gradient is observed with a “hot-spot” (i.e., high illuminance) observed substantially off the floor and a relatively dim area near the base of the shelves. 
         [0043]    In some embodiments, lamps incorporating the optics described herein produce a distribution that (simulated) decrease the illuminance values at higher distances from the floor, reducing “hot-spots” while simultaneously increasing the light levels in the formerly dim areas near the floor. This represents a more consistent illumination (as described in the avg/min and avg/max ratio) without dim portions that is desirable in many applications of interest. It should be noted that this behavior can be predicted mathematically for any lighting system that matches the distribution shown for the LED T8 w/optics. That is, a person of ordinary skill in the art may be able to fabricate the optic necessary from the description herein, together with the light distribution pattern, without any undue experimentation. 
         [0044]    Embodiments have been described herein solely for the purpose of illustration. Persons skilled in the art will recognize from this description that embodiments are not limited to those described, but may be practiced with modifications and alterations limited only by the spirit and scope of the appended claims.