具体实施方式：
[0025]Embodiments of the present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Moreover, the various aspects of the embodiments as described herein may be used in combination with any other aspects of the embodiments as described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
[0026]It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present invention. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
[0027]It will be understood that when an element such as a layer, region or substrate is referred to as being “on” or extending “onto” another element, it can be directly on or extend directly onto the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or extending “directly onto” another element, there are no intervening elements present. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present.
[0028]Relative terms such as “below” or “above” or “upper” or “lower” or “horizontal” or “vertical” or “top” or “bottom” may be used herein to describe a relationship of one element, layer or region to another element, layer or region as illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.
[0029]The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”“comprising,”“includes” and/or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
[0030]Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0031]Unless otherwise expressly stated, comparative, quantitative terms such as “less” and “greater”, are intended to encompass the concept of equality. As an example, “less” can mean not only “less” in the strictest mathematical sense, but also, “less than or equal to.”
[0032]The terms “LED” and “LED device” as used herein may refer to any solid-state light emitter. The terms “solid state light emitter” or “solid state emitter” may include a light emitting diode, laser diode, organic light emitting diode, and/or other semiconductor device which includes one or more semiconductor layers, which may include silicon, silicon carbide, gallium nitride and/or other semiconductor materials, a substrate which may include sapphire, silicon, silicon carbide and/or other microelectronic substrates, and one or more contact layers which may include metal and/or other conductive materials. A solid-state lighting device produces light (ultraviolet, visible, or infrared) by exciting electrons across the band gap between a conduction band and a valence band of a semiconductor active (light-emitting) layer, with the electron transition generating light at a wavelength that depends on the band gap. Thus, the color (wavelength) of the light emitted by a solid-state emitter depends on the materials of the active layers thereof. In various embodiments, solid-state light emitters may have peak wavelengths in the visible range and/or be used in combination with lumiphoric materials having peak wavelengths in the visible range. Multiple solid state light emitters and/or multiple lumiphoric materials (i.e., in combination with at least one solid state light emitter) may be used in a single device, such as to produce light perceived as white or near white in character. In certain embodiments, the aggregated output of multiple solid-state light emitters and/or lumiphoric materials may generate warm white light output having a color temperature range of from about 2200K to about 6000K.
[0033]Solid state light emitters may be used individually or in combination with one or more lumiphoric materials (e.g., phosphors, scintillators, lumiphoric inks) and/or optical elements to generate light at a peak wavelength, or of at least one desired perceived color (including combinations of colors that may be perceived as white). Inclusion of lumiphoric (also called ‘luminescent’) materials in lighting devices as described herein may be accomplished by direct coating on solid state light emitter, adding such materials to encapsulants, adding such materials to lenses, by embedding or dispersing such materials within lumiphor support elements, and/or coating such materials on lumiphor support elements. Other materials, such as light scattering elements (e.g., particles) and/or index matching materials, may be associated with a lumiphor, a lumiphor binding medium, or a lumiphor support element that may be spatially segregated from a solid state emitter.
[0034]As shown in FIGS. 14 and 15 show one embodiment of a traditional fluorescent troffer fixture having a housing 4a that may be recess mounted or flush mounted in a ceiling or other structure. Another embodiment of a fluorescent fixture 4b is shown in FIGS. 8 and 13 having a diffuser lens 5. While embodiments of different types of fixtures are shown, the housing in which the lamp of the invention may be used may comprise a variety of shapes, sizes and configurations. The lamp of the invention may be used in any lighting fixture that uses conventional tombstone connectors. The housing typically supports a ballast and electrical conductors such as wiring that comprise the electrical connection between the lamp's tombstone connectors 10 and a power supply. The power supply may be the electrical grid of a building or other structure or the like. The tombstone connectors 10 connect to two pins formed on each end of a fluorescent tube 13 to provide power to the fluorescent tube. Typically, the ballast, wiring and other electrical components are retained in a compartment or wire way 12 in the housing. The wire way 12 typically comprises a recessed area or trough in the base of the housing. The wire way 12 may be covered by a removable wire way cover 14 such that the only exposed electrical components are the UL approved tombstone connectors 10.
[0035]Because LED based solid state lamps use less energy, are more durable, operate longer, can be combined in multi-color arrays that can be controlled to deliver virtually any color light, and generally contain no lead or mercury the conversion to, or replacement of fluorescent lighting systems with, LED lighting systems is desired. In some existing replacement lamps the entire fluorescent fixture including the troffer must be replaced. The conversion from a fluorescent light to a solid state LED based light may be time consuming and expensive. In the system of the invention, a traditional fluorescent light may be converted to an LED based solid state lamp quickly and easily by replacing the fluorescent bulb with an LED lamp. The LED lamp fits into the same housing as the fluorescent tube and uses the existing tombstone connectors to provide current to the LED lamp. The LED lamp of the invention allows a traditional fluorescent light to be converted to a solid state LED lamp without requiring specialized tools, equipment or training.
[0036]In one embodiment the LED lamp 100 comprises a generally planar or flat base 20. The base 20 may be made of a thermally conductive material such that it functions as a heat sink to dissipate heat from the LED assembly. The base 20 may be made of a rigid material to support the LED assembly 30 and lens 50. In some embodiments the base may be made of extruded aluminum. While aluminum may be used, other rigid, thermally conductive materials and manufacturing processes may be used to form the base 20. While the base 20 is described as planar, the base may have surface irregularities such that while the base is generally planar or flat it is not necessarily a true planar surface. For example, in one embodiment the base comprises a flat member formed to have a centrally disposed longitudinally extending rib 22. The rib 22 provides structural rigidity to the base 20 such that the base 20 does not flex or bend. In other embodiments the base 120 may comprise a planar member 120a where a separate box member 120b is secured to the planar member 120a such as by welding, adhesive fasteners or the like. While a rib 22 may be used in some embodiments to add rigidity to the base 20, the base 220 may comprise a planar member without a reinforcement rib, as shown in FIG. 16, where, for example, the thickness of the base provides sufficient rigidity for the lamp. The rib 22 may be formed such that it extends away from the LED assembly 30 such that a chamber 35 may be provided behind the LED assembly 30, between the LED assembly 30 and the base 20. In the embodiment of FIG. 17 chamber 134 is formed between the planar member 120a and the box member 120b. The chamber 35, 135 may support lamp components such as connectors or the like. In other embodiments the rib 22 may extend to the same side as the LED assembly 30 such that the LED assembly 30 is held in an offset position relative to the remainder of the base 20 as shown in FIG. 18. In the embodiment of FIG. 18 the arrangement of the rib creates an exterior channel 33 that extends along the base and is open to the exterior of the lamp. Any of the bases disclosed herein may be used with any of the translucent lenses disclosed herein. The term planar as used herein to describe the base is intended to define a base that is non-round and that creates a generally flat top surface of the lamp 100. Referring to FIG. 22 the base 20 may be formed with extending fins 23 that create a heat sink to increase the surface area of the base and increase heat transfer to the ambient environment.
[0037]The LED lamp 100 comprises an LED assembly 30 that may be supported by and secured to the base 20. The LED assembly 30 may comprise a plurality of LEDs or LED packages 32 that extend the length of, or substantially the length of, the base 20 to create a desired light pattern. The LEDs 32 may be arranged such that the light pattern extends the length of, or for a substantial portion of the length of, the lamp and is similar in length to a traditional fluorescent bulb. While in one embodiment the LEDs 32 extend for substantially the entire length of the base 20, the LEDs 32 may be arranged in other patterns and may extend for less than substantially the entire length of the base if desired. For example, the LEDs may be disposed along the edges of the LED board 34 and directed toward the middle of the lamp. The LEDs may be directed into a waveguide. The LEDs 32 may be mounted on a LED board 34 that provides physical support for the LEDs 32 and provides an electrical path for providing electrical power to the LEDs. The electrical path provides power to the LEDs and may comprise the power source, board 34 and intervening lamp electronics. The board 34 may comprise MCPCB, FR4, a flex circuit, lead frame or other suitable mounting substrate for the LEDs. The board may comprise the electrical components that form part of the electrical path to the LEDs or electrical conductors may comprise separate elements that are supported by the board. In the illustrated embodiments the base 20 and the LED board 34 are shown as separate physical elements; however, the LED board 34 and the base 20 may be a single element where the LED board has the structural integrity to support the lamp components.
[0038]The LEDs 32 may be provided in a wide variety of patterns and may include a wide variety of different types and colors of LEDs to produce light in a wide variety of colors and/or light patterns. In some embodiments LEDs as disclosed herein may include one or more light affecting elements (including light transmissive, light-absorptive, light reflective and/or lumiphoric materials) formed on, over or around at least one solid state light emitter including fused elements embodying a plurality of dots, rods, or layers such as may be formed by three-dimensional (3D) printing. Further details regarding formation of light affecting elements including fused elements such as may be formed by 3D printing are disclosed in a related U.S. patent application Ser. No. 13/943,043 entitled “SOLID STATE LIGHTING DEVICES AND FABRICATION METHODS INCLUDING LIGHT-AFFECTING ELEMENTS” by Medendorp et al., filed Jul. 16, 2013, the disclosure of which is incorporated by reference herein in its entirety. In some embodiments, the LED assembly 30 may comprise more than one board where the boards are connected to one another at a connector 33 to provide an electrical path between the individual boards. The connector 33 comprises mating electrical connectors on the boards such that the mating electrical connectors may be connected to create an electrical path along the length of the board. In the illustrated embodiment the connector 33 is shown on the opposite surface of board 34 from the LEDs such that the connector 33 is located in the chamber 35. Alternatively, the connector may be on the same side of the board as the LEDs. One embodiment of a LED lamp and suitable LED structure is shown and described in U.S. patent application Ser. No. 12/873,303 entitled “Troffer-Style Fixture” filed on Aug. 31, 2010, which is incorporated by reference herein in its entirety. Example embodiments of interfacing one or more LEDs to AC-output lighting ballasts are described in a related U.S. patent application Ser. No. 13/943,376 entitled “LED LIGHTING APPARATUS FOR USE WITH AC-OUTPUT LIGHTING BALLASTS” by Zhang et al., filed Jul. 16, 2013, the disclosure of which is incorporated by reference herein in its entirety. Example embodiments of interfacing LED strings to fluorescent emergency lighting ballasts are described in a related U.S. patent application Ser. No. 13/943,455 entitled “EMERGENCY LIGHTING CONVERSION FOR LED STRINGS” by McBryde et al., filed Jul. 16, 2013, the disclosure of which is incorporated by reference herein in its entirety. Example embodiments of suitable driver circuitry for use in the lamp of the invention are described in U.S. application Ser. No. 14/055,264 entitled “SOLID-STATE LIGHTING APPARATUS WITH FILIAMENT IMITATION FOR USE WITH FLORESCENT BALLASTS” by Zhang, filed Oct. 16, 2013, the disclosure of which is incorporated by reference herein in its entirety; and U.S. application Ser. No. 14/256,573 entitled “SOLID-STATE LIGHTING APPARATUS WITH FILIAMENT IMITATION FOR USE WITH FLORESCENT BALLASTS” by Zhang, filed Apr. 18, 2014, the disclosure of which is incorporated by reference herein in its entirety. The driver circuitry described herein and as used in the lamp may use the existing fluorescent ballast in some embodiments.
[0039]The board 34 may be supported by the base 20 such that the board 34 and LEDs 32 are supported for the length of the lamp. In one embodiment the base 20 comprises a first inwardly opening C-channel 40 that extends along the length of one side of the base 20 and a second inwardly opening C-channel 42 that extends along the length of the opposite side of the base 20. In one embodiment the channels 40, 42 extend for the length of the base 20; however, the channels 40, 42 may extend for less than the entire length of the base 20 provided that they adequately support and retain the board 34. For example, gaps may be provided in the channels 40, 42. The channels 40, 42 face one another to create a receptacle for receiving the board 34. In one embodiment the longitudinal edges of the board 34 are inserted into the channels 40, 42 such that the board 34 may be retained in the channels 40, 42 and supported on the base 20. The board 34 may be retained by friction, a mechanical engagement, a pressure fit, adhesive, mechanical connector or other connection mechanism. To assemble the board 34 and base 20 the board may be inserted into the channels from one end of the base 20 and slid into engagement with the channels 40, 42. The board 34 is thermally coupled to the base 20 such that heat generated by the LEDs 32 is transferred to the base 20 via the board 34 and is dissipated to the ambient environment by the base 20. The thermal couple between the board 34 and base 20 may be provided by providing surface to surface contact between the board and the base. In other embodiments thermally transmissive layers may be provided between the base and the board. For example, thermal adhesive may be used to attach the board 34 to the base 20.
[0040]The LED assembly 30 may be made removable from the base 20 for maintenance purposes or to vary the light output for different applications. The LED assembly 30 may be made removable by attaching the board 34 to the base 20 using a releasable connection mechanism such as, but not limited to, a friction fit or a snap-fit connection, screws or other releasable fasteners or the like. The base 20 and LED assembly 30 may be made of a reflective material, e.g., MCPET, white optic, or the like, to reflect light from the mixing chamber 51. The entire base and/or board may be made of a reflective material or portions of the base and/or board may be made of reflective material. For example, portions of the base and/or board that may reflect light may be made of reflective material.
[0041]A lens 50 may be connected to the base 20 to cover the LED assembly 30 and create a mixing chamber 51 for the light emitted from the LEDs 32. The light is mixed in the chamber 51 and the lens 50 diffuses the light to provide a uniform, diffuse, color mixed light pattern. The lens 50 may be made of molded plastic or other material and may be provided with a light diffusing layer. The light diffusing layer may be provided by etching, application of a coating or film, by the translucent or semitransparent material of the lens, by forming an irregular surface pattern during formation of the lens or by other methods. Because the lens has a flattened non-round profile, a greater distance between the LEDs and the lens can be provided than with a round lens having the same height. As a result more optical spreading distance is provided between the lens and the LEDs to provide better mixing.
[0042]In some embodiments the lens 50 has a dome-shaped cross-sectional profile as shown for example in FIGS. 2 and 3. The lens 50 extends substantially the length of the base 20 to cover the LEDs 32 supported on the base 20. In some embodiments, the longitudinal edges 50a, 50b of the lens 50 are provided with inwardly facing lips or projections 52 and 54 that may be received in outwardly facing longitudinal C-channels 56, 58 formed along the longitudinal edges of the base 20. The lens 50 and projections 52, 54 may be formed as one piece such as by a plastic molding process. In some embodiments, the base 20 may be formed of extruded, stamped or rolled metal where the channels 56 are formed as one-piece with the base; however, the channels may be separately attached to the base. The projections 52, 54 are inserted into the channels 56, 58 to retain the lens 50 on the base 20. The projections 52, 54 may be slid into the channels 56, 58 from the end of the base 20. If the lens 50 is made of an elastic material, such as molded plastic, the projections 52, 54 may also be inserted into the channels 56, 58 by inserting a first projection 52 into one of the channels 56 and deforming the lens to insert the opposite projection 54 into the opposite channel 58. The lens 50 may then be released such that the lens elastically returns to its original shape where the projections 52, 54 are forced into the opposed channels 56, 58. As shown in the figures in some embodiments the base 20 has a generally planar shape with an S-channel formed along the longitudinal edges thereof. The S-channel defines inwardly facing channels 40, 42 for receiving the board 34 and outwardly facing channels 56, 58 for receiving the projections 52, 54 of lens 50.
[0043]As illustrated in the figures the lens 50 is arranged such that the lens 50 extends above or behind the plane A-A of the LEDs 32. Behind as used herein means toward the side of the board opposite the LEDs. In other words, from a point located on the LED 32 the lens 50 extends for an angle α greater than 180 degrees (or greater than 90 degrees in each direction from a line that extends perpendicularly from the LED). In some embodiments the lens 50 may extend at an angle α greater than 215 degrees. In other embodiments, the lens 50 may extend at an angle α greater than 270 degrees. Moreover, to the lateral sides of the LEDs the base and LED board do not include any portions that extend to block light emitted by the LEDs. The planar LED board and base 20 do not obstruct light emitted laterally from the LEDs. As a result of this arrangement some of the light generated by the LEDs 32 is directed as backlight in a direction behind the plane A-A of the LEDs 32. The light is directed toward the light housing 4a, 4b where it can be reflected by the housing to create a light distribution pattern that is similar to the light distribution pattern of a traditional fluorescent system. It will be understood that in a traditional fluorescent system the fluorescent tube generates light over 360 degrees. As a result, some of the light generated by the fluorescent tube is reflected from the housing. By arranging the lens 50 such that it extends behind the plane A-A of the LEDs 32. Some of the light generated by the LEDs 32 may be emitted directly out of the lamp as backlight while additional light may be reflected off of the lens 50 and emitted as backlight. Such an arrangement provides an LED lighting system that provides a light distribution pattern that is similar to legacy fluorescent tube lights. In some embodiments, the LEDs may be center mounted with greater side emitting optical profiles such as CREE XPQ LEDs. In some embodiments a prismatic lens or parabolic reflectors may be used to create a desired light distribution. In some embodiments the lens 50 may not include side walls such that the lens covers only the bottom of the lamp with the sides of the enclosure open to the external environment.
[0044]Further, as shown in FIG. 3 the lens 50, in some embodiments, may be configured such that the width of the lens 50 at its widest portion B is larger than the width W of the base 20. In other words the ratio of the base width W to the maximum lens width B is less than 1. As a result light may be emitted from the lens 50 as backlight that is not blocked by the base 20. The backlight may be reflected from the light housing 4 to create the light distribution pattern described above.
[0045]Referring to FIG. 19 an alternate embodiment of the lens 50 is shown where the lens is provided with a cross-sectional profile where the lens has a relatively square or rectangular shape. FIG. 20 illustrates another embodiment of the lens 50 where the lens comprises faceted profile where the lens comprises a plurality of planar surfaces 50a-50g. The lens may comprise a regular or irregular polygon such and may include a wide variety of number of surfaces such as 4, 5, 6, 7, 8, 9, 10 or more sides. FIG. 21 illustrates another embodiment of the lens 50 where the lens comprises a generally triangular profile. While the illustrate lens terminates a flat face 50h that extends generally parallel to the base 20 the lens may terminate in a corner where sides 50i meet at an acute angle. The lens is disposed as previously described where the lens 50 extends above or behind the plane A-A of the LEDs 32. Further, as previously explained the width of the lens 50 at its widest portion B is larger than the width W of the base 20. In other words the ratio of the base width W to the maximum lens width B is less than 1. As a result light may be emitted from the lens 50 as backlight that is not blocked by the base 20.
[0046]In some embodiments the lens 50 and base 20 are arranged such that the LEDs mounted on the base 20 are disposed in the top 30-35% of the height of the lens and in some embodiments the LEDs mounted on the base 20 are disposed in the top 25% of the height of the lens. Referring to FIG. 3, if the lens has a height of H, then the base 20 and LEDs 32 are disposed between the top of the lamp and a distance 0.25H from the top of the lamp for example. Arranging the LEDs in such a position relative to the overall height of the lamp allows the lens to be disposed such that backlight is created as previously described.
[0047]In one embodiment a lamp as described herein comprises 105 XH-G LEDs manufactured and sold by CREE, INC. Such a lamp may have a total Lumen output of approximately between 2,200 and 2,300 Lumens, and more specifically 2,244 Lumens. In this embodiment approximately 389 Lumens or 17.3% of the total Lumen output is emitted as backlight (zone 90-180) with the remaining Lumens emitted as light toward the front of the lamp. Charts showing the Lumen output per zone of the lamp are set forth below.
[0048]Zonal Lumen SummaryZoneLumens% Luminaire0-30412.518.4%0-40684.930.5%0-601,266.556.4%60-90 588.326.2%70-100444.019.8%90-120255.311.4%0-901,854.982.7%90-180389.017.3% 0-1802,243.9 100%Lumens Per ZoneZoneLumens% Total0-512.50.6% 5-1037.01.7%10-1560.62.7%15-2082.43.7%20-25101.84.5%25-30118.35.3%30-35131.45.9%35-40141.06.3%40-45146.76.5%45-50148.46.6%50-55146.26.5%55-60140.26.3%60-65131.05.8%65-70119.25.3%70-75105.34.7%75-8090.74.0%80-8576.93.4%85-9065.32.9%90-9556.42.5% 95-10049.52.2%100-10544.0 2%105-11039.31.8%110-11535.01.6%115-12031.11.4%120-12527.41.2%125-13023.81.1%130-13520.30.9%135-14017.00.8%140-14513.80.6%145-15010.80.5%150-1558.10.4%155-1605.80.3%160-1653.80.2%165-1702.10.1%170-1750.7 0%175-1800.1 0%
[0049]In another embodiment 120 XH-G LEDs manufactured and sold by CREE, INC. are used. Charts showing the Lumen output per zone of the lamp are set forth below. The total lumen backlight (zone 90-180) is about 14.6% of the total lumen output. Such a lamp may have a total Lumen output of approximately between 2,300 and 2,400 Lumens, and more specifically about 2,322 Lumens. In the example embodiments used to create the zonal Lumen results described herein, the lamp was connected to an existing ballast using the driver circuitry described herein, and as specifically described in U.S. application Ser. No. 14/055,264 entitled “SOLID-STATE LIGHTING APPARATUS WITH FILIAMENT IMITATION FOR USE WITH FLORESCENT BALLASTS” by Zhang, filed Oct. 16, 2013, the disclosure of which is incorporated by reference herein in its entirety; and U.S. application Ser. No. 14/256,573 entitled “SOLID-STATE LIGHTING APPARATUS WITH FILIAMENT IMITATION FOR USE WITH FLORESCENT BALLASTS” by Zhang, filed Apr. 18, 2014, the disclosure of which is incorporated by reference herein in its entirety.
[0050]Zonal Lumen SummaryZoneLumens% Luminaire0-20203.70 8.80%0-30436.4318.80%0-40725.5731.20%0-601347.5158.00%0-801830.6878.80%0-901983.2585.40%10-90 1930.8383.20%20-40 521.8722.50%20-50 836.7436.00%40-70 892.4038.40%60-80 483.1720.80%70-80 212.71 9.20%80-90 152.57 6.60%90-110201.87 8.70%90-120269.0911.60%90-130313.3613.50%90-150338.4714.60%90-180338.8014.60%110-180 136.94 5.90% 0-1802322.05100.00% ZoneLumens 0-1052.4210-20151.2920-30232.7330-40289.1440-50314.8750-60307.0760-70270.4670-80212.7180-90152.57 90-100112.94100-11088.92110-12067.23120-13044.27130-14021.15140-1503.97150-1600.09160-1700.15170-1800.09
[0051]An explanation of the above-referenced charts will be provided with reference to FIG. 3. Each zone is defined by an angle β where the angle β is the angle between a first line extending from the LEDs 32 at the first value of the zone and a second line extending from the LEDs 32 at the second value of the zone, where a line extending perpendicularly from the LEDs toward the front of the lamp (i.e. toward the lens 50) is angle 0. The actual zone includes the space bounded by the lines that are defined by angle β and the negative angle β. Thus, for example, zone 0-30 defines a three-dimensional space included between β from 0 to 30 degrees and −β from 0 to 30 degrees for the length of the lamp. In other words, zone 0 to 30 is a 60 degree section of the emitted light that extends for the length of the lamp. In another example zone 90-180 is a zone where β starts at 90 degrees (parallel to the board 34) and ends at 180 degrees and −β starts at 90 degrees (parallel to the board 34) and ends at 180 degrees such that the zone is 180 degree section of the emitted light that extends for the length of the lamp. Light emitted in zone 90-180 defines backlight of the lamp. Thus, for any designated zone angle, the zone includes two three-dimensional sections of the lamp, one section defined by the angle range β and one defined by the same angle range at −β.
[0052]In some embodiments the distribution of light may be considered in terms of lumen output or in terms of percentage of lumen output. In some embodiments the LED assembly and lens are configured as described herein such that approximately between 5 and 25 percent of the total Lumen output of the lamp is emitted as backlight, and in some embodiments approximately between 10 and 20 percent of the total Lumen output of the lamp is emitted as backlight; and in one embodiment approximately between 13 and 18 percent of the total Lumen output of the lamp is emitted as backlight. Depending on the orientation and light distribution of the LEDs and the lens shape and size relative to the base, the light distribution can yield a lower or higher percentage of backlight. In different embodiments the lamp may comprise 140, 120 or 105 XH-G LEDs may be used although different numbers, types and arrangements of LEDs are possible. In some embodiments approximately between 105 and 600 Lumens are emitted as backlight, and in some embodiments approximately between 210 and 480 Lumens are emitted as backlight; and in one embodiment approximately between 273 and 432 Lumens are emitted as backlight. The light may be at different color temperatures. In some embodiments, the color temperature is between 3000K and 4500K, between about 3400K and 4100K. And, in some embodiments the color temperature may be about 3500K and about 4000K. Different CRI values are possible such as at least 80, at least 85 or at least 90. In one embodiment the CRI may be about 90. In another exemplary embodiment the LED assembly comprises 120 XH-G LEDs manufactured and sold by CREE, INC. In some embodiments the lamp may have a total Lumen output of approximately 2100 Lumens at least 100 Lumens per watt. The lamp may have a total Lumen output of approximately 2000 Lumens or greater. The output numbers may also fluctuate based on the existing ballast being used.
[0053]End caps 60 may be provided at the opposi