This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 104207617 filed in Taiwan, R.O.C. on May 18, 2015, the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to the field of LED light bulbs, and more particularly to an axially symmetric LED light bulb with the features of high light uniformity and wide-angle illumination range.
2. Description of the Related Art
LED with the features of high efficiency, high color rendering, environmental friendliness, energy saving and long service life is used generally used as a light source for various illumination lamps.
For example, the conventional light bulb at an early stage uses a tungsten filament as the light source, wherein electricity is passed through the tungsten filament, and the tungsten filament is heated to incandescence to emit light for the illumination purpose due to the resistance of the tungsten filament. The light emission of such light bulb is similar to that of a light source, so that when such light bulb is used for illumination, a luminous efficacy of 360-degree full-circumferential radiation is achieved. A s described above, LEDs are used extensively as a light source for lamps, but most of the light sources in the present LED light bulbs are designed with a light emitting surface facing upward and perpendicular to the light emitting angle. In the meantime, the shape and structure of the light bulb provides a screening effect to the light, so that the light emitting angle of the conventional LED light bulb is usually not too large, and the light is too concentrated and comes with a narrow light emitting angle. With the aforementioned restrictive properties including the light emitting angle and the total light lumen of the LED, the conventional LED light bulb is unable to achieve the full-circumferential uniform illumination effect like the conventional incandescent lamps with the feature of a uniform wide-angle light emission. Therefore, the conventional LED light bulb still requires improvements of the illumination angle and the uniformity of light to achieve a better illumination performance of the LED light bulb.
To improve the luminous efficacy of the LED light bulb, most manufacturers adopt a 3D light source to increase the illumination angle of the LED light bulb, such that the LED light bulb can achieve the effect of a full-circumferential illumination similar to that of the tungsten filament. With reference to
Therefore, the present methods adopted for improving the light output angle and uniformity of the LED light bulb increase the manufacturing cost, the assembling time and the level of difficulty of the design. Although these methods may overcome the issue of a low luminous efficacy of the LED light bulb, yet they still have the following drawbacks. Therefore, the inventor of the present invention provides an axially symmetric LED light bulb in hope of overcoming the drawbacks of the conventional LED light bulb and improving the illumination angle and light uniformity of the LED light bulb with planar light emission to omit the complicated design of the light source and lower the production cost.
Therefore, it is a primary objective of the present invention to provide an axially symmetric LED light bulb capable of adjusting the upward LED light output angle with respect to the light emitting surface and homogenizing the overall light uniformity to provide the wide-angle light emitting angle and excellent illumination uniformity similar to those of a full-circumferential radiation.
To achieve the aforementioned and other objectives, the present invention provides an axially symmetric LED light bulb comprising a lamp shade, a substrate and a connecting seat, and the substrate being installed on the connecting seat and having a plurality of LED light sources, and an edge of the lamp shade being coupled to the connecting seat and the substrate being covered inside the lamp shade, characterized in that the lamp shade has an unequal thickness, and the thickness of the top of the lamp shade is greater than the thickness of the lateral side of the lamp shade, such that the LED light source is arranged at a polar coordinate origin position, and when the illumination of LED light source points at a direction towards the polar coordinate 0 degree and after the light of the LED light source passes through the lamp shade, at least 5% of the total flux of the LED light source is obtained at the polar coordinate position from 135 degrees to 180 degrees. The axially symmetric LED light bulb 2 further satisfy a illumination relation (|I−Iavg|/Iavg)<25%, wherein I is an intensity of light of at least 90% of a spatial position between 0 degree to 135 degrees of the polar coordinate positions, and Iavg is an average light intensity situated between the polar coordinate position from 0 degree to 135 degrees.
Wherein, the ratio of the thickness of the lamp shade at the polar coordinates from +30 degrees to −30 degrees to the thickness of the lamp shade at the polar coordinates from +90 degrees to +30 degrees and from −90 degrees to −30 degrees is equal to (1.8−3):1. Within this range, the present invention meets the conditions of the optimal light uniformity and wide-angle illumination angle and achieves the best lighting performance.
In addition, the cross-sectional edge of the inner side of the lamp shade is arc-shaped or is a curve with a plurality of turning points, and the curve is bilaterally symmetrical, and the distance from the top end of the inner side of the lamp shade to the substrate is equal to 50 mm-60 mm, and the maximum width of the external periphery of the lamp shade is equal to 58 mm-70 mm.
In summation of the description above, the axially symmetric LED light bulb of the present invention effectively improves the luminous efficacy of a light bulb that uses LED as a light source, and the lamp shade with unequal thickness reduces a too-strong light of the LED light source generated at specific angles, so that the light of the light bulb at a predetermined light output angle is more uniform and the illumination angle is wider.
The technical content of the present invention will become apparent with the detailed description of preferred embodiments and the illustration of related drawings as follows. It is noteworthy that same numerals are used for representing the same respective elements respectively for simplicity.
With reference to
The axially symmetric LED light bulb 2 is characterized in that the lamp shade 20 has an unequal thickness, wherein the thickness of the top of the lamp shade 20 is greater than the thickness of the lateral side of the lamp shade 20, so that the lamp shade 20 comes with an unequal thickness. Please refer to
The following data are obtained from optical experiments, and these data relate to the thickness ratios of the lamp shade 20 (hereinafter referred to as “thickness ratio”) at the polar coordinate from +30 degrees to −30 degrees with respect to the polar coordinate +90 degrees to +30 degrees and −90 degrees to −30 degrees. The thickness of the lamp shade 20 at the polar coordinate from +30 degrees to −30 degrees and the thickness of the lamp shade 20 at the polar coordinate from +90 degrees to +30 degrees and from −90 degrees to −30 degrees are obtained after conducting the optical experiments, and if their ratio is equal to (1.8−3):1, the aforementioned restrictive condition of the flux and the light emitting intensity is met, and the axially symmetric LED light bulb 2 achieves the effects of full circumferential luminous efficacy and light uniformity.
Firstly, optical experiments on testing whether or not the light emitting intensity satisfies the relation (|I−Iavg|/Iavg)<25% are conducted repeatedly, and the experiment results are listed in Tables 1-1 to 1-5. Wherein, Tables 1-1 to 1-5 show the numeric values of the measured light intensity at the polar coordinate positions (γ,c) and the measured average light intensity Iavg as shown in
Table 1-1 lists the experiment data provided that the thickness ratio of the lamp shade 20 is 1:1 and shows the light emitting intensity I at each spatial position within the polar coordinate positions from 0 degree to 135 degrees and the numeric value of (|I−Iavg|/Iavg) of the average light intensity Iavg; Table 1-2 lists the experiment data provided that the thickness ratio of the lamp shade 20 is 1.7:1, and shows the light emitting intensity I at each spatial position within the polar coordinate positions from 0 degree to 135 degrees and the numeric value of (|I−Iavg|/Iavg) of the average light intensity Iavg; Table 1-3 lists the experiment data provided that the thickness ratio of the lamp shade 20 is 1.8:1, and shows the light emitting intensity I at each spatial position within the polar coordinate positions from 0 degree to 135 degrees and the numeric value of (|I−Iavg|/Iavg) of the average light intensity Iavg; Table 1-4 lists the experiment data provided that the thickness ratio of the lamp shade 20 is 3:1, and shows the light emitting intensity I at each spatial position within the polar coordinate positions from 0 degree to 135 degrees and the numeric value of (|I−Iavg|/Iavg) of the average light intensity Iavg; and Table 1-5 lists the experiment data provided that the thickness ratio of the lamp shade 20 is 3.1:1, and shows the light emitting intensity I at each spatial position within the polar coordinate positions from 0 degree to 135 degrees and the numeric value of (|I−Iavg|/Iavg) of the average light intensity Iavg, wherein the numeric values listed in each table is in the unit of %.
In Tables 1-1 to 1-5, the experiment results of the aforementioned different thickness ratios are combined as shown in Table 2. In Table 2, when the thickness ratio of the lamp shade 20 is 1:1, the number of spatial coordinates not complying with (|I−Iavg|/Iavg)<25% is equal to 156, which is 16.68% of the total number of spatial coordinates, so that it does not meet the requirement of having at least 90% of the coordinates satisfying (|I−Iavg|/Iavg)<25%; when the thickness ratio of the lamp shade 20 is 1.7:1, the number of spatial coordinates not complying with (|I−Iavg|/Iavg)<25% is equal to 96 which is 10.26% of the total number of spatial coordinates, so that it does not meet the requirement of having at least 90% of the coordinates satisfying (|I−Iavg|/Iavg)<25%; when the thickness ratio of the lamp shade 20 is 1.8:1, the number of spatial coordinates not complying with (|I−Iavg|/Iavg)<25% is equal to 62, which is 6.63% of the total number of spatial coordinates, so that it meets the requirement of having at least 90% of the coordinates satisfying (|I−Iavg|/Iavg)<25%; when the thickness ratio of the lamp shade 20 is 3:1, the number of spatial coordinates not complying with (|I−Iavg|/Iavg)<25% is equal to 17, which is 1.81% of the total number of spatial coordinates, so that it meets the requirement of having at least 90% of the coordinates satisfying (|I−Iavg|/Iavg)<25%; and when the thickness ratio of the lamp shade 20 is 3.1:1, the number of spatial coordinates not complying with (|I−Iavg|/Iavg)<25% is equal to 145, which is 15.5% of the total number of spatial coordinates, so that it does not meet the requirement of having at least 90% of the coordinates satisfying (|I−Iavg|/Iavg)<25%.
In addition to the measurement of the numeric values of the light intensity I at each spatial position within the polar coordinate positions from 0 degree to 135 degrees, and the calculation of the numeric values of the relation of the average light intensity Iavg within the polar coordinate positions from 0 degree to 135 degrees, the present invention also measures the flux of the LED light sources 211 at the polar coordinate positions from 135 degrees to 180 degrees and calculates the total flux of the LED light sources 211 to obtain the numeric value of the cumulative percentage of the total flux at the polar coordinate positions from 135 degrees to 180 degrees. Experiments are performed for different thickness ratios of the lamp shade 20, and the experiment results are listed in Tables 3-1 to 3-5. Table 3-1 lists the experiment results for the thickness ratio of the lamp shade 20 equal to 1:1; Table 3-2 lists the experiment results for the thickness ratio of the lamp shade 20 equal to 1.7:1; Table 3-3 lists the experiment results for the thickness ratio of the lamp shade 20 equal to 1.8:1; Table 3-4 lists the experiment results for the thickness ratio of the lamp shade 20 equal to 3:1; and Table 3-5 lists the experiment results for the thickness ratio of the lamp shade 20 equal to 3.1:1, wherein γ(∘) is the angle at the polar coordinate position; Average 1(cd) is the average light intensity at each angular position which is measured in the unit of candle (cd); Zonal F(lm) is the regional flux at each angular position, which is measured in the unit of lumen (lm); Sum F(lm) is the sequentially cumulative flux at each angular position, which is measured in the unit of lumen (Im); Eff Fiux(%) is the percentage (%) of the flux at each angular position with respect to the total flux; and Eff Sum(%) is the cumulative percentage of the flux at each angular position with respect to the total flux, which is measured in the unit of percent (%).
From the numeric values listed in the cumulative fields of the flux at each angular position with respect to the total flux as shown in Tables 3-1 to 3-5, we know that when the thickness ratio of the lamp shade 20 is 1:1, the flux of the polar coordinate positions from 135 degrees to 180 degrees is approximately equal to 6.431% of the total flux of the LED light sources 211; when the thickness ratio of the lamp shade 20 is 1.7:1, the flux of the polar coordinate positions from 135 degrees to 180 degrees is approximately equal to 7.372% of the total flux of the LED light sources 211; when the thickness ratio of the lamp shade 20 is 1.8:1, the flux of the polar coordinate positions from 135 degrees to 180 degrees is approximately equal to 7.699% of the total flux of the LED light sources 211; when the thickness ratio of the lamp shade 20 is 3:1, the flux of the polar coordinate positions from 135 degrees to 180 degrees is approximately equal to 8.379% of the total flux of the LED light sources 211; and when the thickness ratio of the lamp shade 20 is 3.1:1, the flux of the polar coordinate positions from 135 degrees to 180 degrees is approximately equal to 8.733% of the total flux of the LED light sources 211. Although the flux of the testing items can reach up to 5% of the total flux of the LED light source 21 at the polar coordinate position from 135 degrees to 180 degrees provided that the thickness ratio of the lamp shade 20 is 1:1, 1.7:1, 1.8:1, 3:1 or 3.1:1, yet the present invention is characterized in that the axially symmetric LED light bulb 2 not just achieves a brightness with a flux equal to 5% of the total flux of the LED light sources 211 at the polar coordinate position from 135 degrees to 180 degrees only, but also satisfy the relation (|I−Iavg|/Iavg)<25%, wherein, I is an intensity of light of at least 90% of a spatial position between the polar coordinate positions from 0 degree to 135 degrees, and Iavg is an average light intensity between the polar coordinate positions from 0 degree to 135 degrees. With reference to the aforementioned experiment results, the expected illumination effect of the present invention has not been achieved when the lamp shade 20 has a thickness ratio of 1:1, 1.7:1 or 3.1:1.
With reference to
Preferably, the edge of a sectional line on an inner side of the lamp shade 20 is an arc, or a curve having a plurality of turning points, wherein the curve is laterally symmetrical. In this preferred embodiment, the edge of the sectional line on the inner side of the lamp shade 20 is an arc. In addition, the distance L from the top of the inner side of the lamp shade 20 to the substrate 21 is 50 mm-60 mm, and the maximum width W of the external periphery of the lamp shade 20 is 58 mm-70 mm.
In summation of the description above, the present invention focuses at the LED light bulbs with a light emitting surface that faces upward, and makes use of the lamp shade 20 of unequal thickness to reduce the light intensity of the LED light sources 211 at specific angles to scatter the light to predetermined light output angle and achieve a uniform light emitting effect and a wide-angle illumination range, so as to overcome the drawbacks of the conventional LED light bulb including non-uniform light emission and too-concentrated light angle effectively.
Number | Date | Country | Kind |
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104207617 | May 2015 | TW | national |
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Number | Date | Country | |
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20160341367 A1 | Nov 2016 | US |