Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V3/00—Globes; Bowls; Cover glasses
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21K—NON-ELECTRIC LIGHT SOURCES USING LUMINESCENCE; LIGHT SOURCES USING ELECTROCHEMILUMINESCENCE; LIGHT SOURCES USING CHARGES OF COMBUSTIBLE MATERIAL; LIGHT SOURCES USING SEMICONDUCTOR DEVICES AS LIGHT-GENERATING ELEMENTS; LIGHT SOURCES NOT OTHERWISE PROVIDED FOR
  • F21K9/00—Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
  • F21K9/20—Light sources comprising attachment means
  • F21K9/23—Retrofit light sources for lighting devices with a single fitting for each light source, e.g. for substitution of incandescent lamps with bayonet or threaded fittings
  • F21K9/232—Retrofit light sources for lighting devices with a single fitting for each light source, e.g. for substitution of incandescent lamps with bayonet or threaded fittings specially adapted for generating an essentially omnidirectional light distribution, e.g. with a glass bulb
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V3/00—Globes; Bowls; Cover glasses
  • F21V3/04—Globes; Bowls; Cover glasses characterised by materials, surface treatments or coatings
  • F21V3/06—Globes; Bowls; Cover glasses characterised by materials, surface treatments or coatings characterised by the material
  • F21V3/062—Globes; Bowls; Cover glasses characterised by materials, surface treatments or coatings characterised by the material the material being plastics
  • F21V3/0625—Globes; Bowls; Cover glasses characterised by materials, surface treatments or coatings characterised by the material the material being plastics the material diffusing light, e.g. translucent plastics
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V29/00—Protecting lighting devices from thermal damage; Cooling or heating arrangements specially adapted for lighting devices or systems
  • F21V29/50—Cooling arrangements
  • F21V29/70—Cooling arrangements characterised by passive heat-dissipating elements, e.g. heat-sinks
  • F21V29/74—Cooling arrangements characterised by passive heat-dissipating elements, e.g. heat-sinks with fins or blades
  • F21V29/77—Cooling arrangements characterised by passive heat-dissipating elements, e.g. heat-sinks with fins or blades with essentially identical diverging planar fins or blades, e.g. with fan-like or star-like cross-section
  • F21V29/773—Cooling arrangements characterised by passive heat-dissipating elements, e.g. heat-sinks with fins or blades with essentially identical diverging planar fins or blades, e.g. with fan-like or star-like cross-section the planes containing the fins or blades having the direction of the light emitting axis
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
  • F21Y2105/00—Planar light sources
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
  • F21Y2115/00—Light-generating elements of semiconductor light sources
  • F21Y2115/10—Light-emitting diodes [LED]

Definitions

• the present invention relates to bulb-shaped LED light sources.
• Figure 7 is a cross sectional view showing a conventional LED bulb 200.
• the objective of the LED bulb 200 is to provide an LED bulb with which white light can be obtained with uniform luminance over a wide area of illumination using a simple configuration, and with which the light distribution pattern can be altered simply, which can be connected directly to an ordinary commercial power supply and which is compatible with commonly used incandescent light bulbs.
• the LED bulb 200 comprises a cover 202 which is provided at one end with a metal cap 201 and which widens in a trumpet shape toward an opening at the other end, an outer tube globe 205 having a light diffusing layer 206 on its inner surface and fitted to the opening of the cover 202, a substrate 203 provided inside a substantially spherical body 207 formed from the cover 202 and the outer tube globe 205, and LED elements 204 mounted onto the outer surface of the substrate 203 facing the outer tube globe 205.
• the outer tube globe 205 may also comprise a uniform material (such as acrylic) having a light diffusing effect.
• the substrate 203 is plate-shaped and parallel to the outer surface of the opening of the cover 202.
• a plurality of LED elements 204 are arranged on the planar substrate 203 (see for example Patent literature article 1) .
• Patent literature article 1 Japanese Patent Kokai 2001-243807 [Summary of the invention]
• LED bulb 200 With such an LED bulb 200, light emitted from the LED elements 204 illuminates the outer tube globe 205, and in some areas light from a plurality of LED elements 204 overlaps, while other parts are outside the illuminated area. In other words, there is a problem of non-uniform brightness.
• the LED elements 204 are arranged on the same substrate 203 facing in the same illumination direction, the light distribution characteristics are completely different from an electric bulb or bulb-shaped fluorescent lamp even though the shape of the commercial product looks the same as an electric bulb, as the emitted light is concentrated in only one direction, as with a spotlight, perpendicular to the surface of the substrate 203.
• n the number of LED elements 204, where n is a natural number
• n the number of LED elements 204, where n is a natural number
• a factor that influences the luminous efficacy is that with a diffusion filter (outer tube globe 205) perpendicular to the optical axis of the illuminating light almost all of the light enters and passes through the filter medium while being attenuated. This is called the in-line transmittance. However, if light enters the filter obliquely, with an angle between its optical axis and the filter, then a portion of the light is reflected without entering the filter medium. In the case of the LED bulb 200, light reflected within the outer tube globe 205 is further reflected multiple times, and is separated into light that is illuminated out of the outer tube globe 205 and light that is lost within the outer tube globe 205.
• the present invention aims to overcome problems such as those mentioned above by providing a bulb-shaped LED light source with which the luminance uniformity ratio on an outer tube globe similar to an incandescent light bulb is improved, in other words with which the occurrence of light non-uniformities can be reduced, without reducing efficiency.
• the design method to be employed was limited to a design in which all of the LED elements have the same light distribution angle, eliminating the need for complex identification or distinct usage of LED elements, and in which the LED elements are installed with the same illumination direction on a substrate, and in which all of the optical axes are in a direction perpendicular to the surface of the substrate.
• the design should preferably be such that there is uniform distribution of light in the lower hemisphere, and also a similar distribution of light in the upper hemisphere, but realistically LED elements do not yet exist that would be able to satisfy such demands, and our aim was thus a design whereby light distribution in the lower hemisphere is as uniform as possible, and whereby directly-downward illumination intensity is distributed to some extent.
• the in-line transmittance of the outer tube globe was set to be approximately 90%.
• this transmittance is a phenomenon that is essentially independent of the present invention, and the advantages of the present invention are not limited to 90%.
• the light distribution angle is the two-dimensional angle from the central axis to the angle at which the light intensity has reduced to 50% of the value on the central axis, where said angle is the angle from the central axis as viewed from the luminescent center of the LED. In other words it is the angle on both sides of the central axis at which the light intensity has reduced to 50%. Therefore, although in practice a small amount of light illuminates outside of this area, the light distribution area is defined here as the area inside the light distribution angle of the LED, in order for design verification to be unambiguous.
• the bulb-shaped LED light source according to the present invention is a bulb-shaped LED light source being a light source of a type that has a built-in lighting circuit and can be lit using a commercial power supply, emitting light over a range of approximately 2nSt (steradian), using LED (light emitting diode) elements as a light source, having an electric bulb-shaped appearance, and not having a wide light distribution like that of an electric bulb, and being an alternative light source to an incandescent light bulb having an E or B metal cap, and further having an outer tube globe in front of the LED light source in imitation of an incandescent light bulb, characterized in that:
• each LED element has a light distribution angle of at least 60° and 120° or less, and the central axis of the light distribution angle is perpendicular to the surface of the substantially planar substrate;
• n overlapping light distribution areas comprise at least 10% and no more than 80% of the inner surface of the outer tube globe.
• the bulb-shaped LED light source according to the present invention is characterized in that the area not included in the light distribution area of any of the LED elements is less than 30% of the inner surface of the outer tube globe.
• the bulb-shaped LED light source according to the present invention by employing the abovementioned configuration it is possible to improve the luminance uniformity ratio on the outer tube globe without reducing the efficiency, in other words to reduce the occurrence of light non-uniformities.
• FIG. 1 is a diagram showing mode of embodiment 1, being a side elevation (a) and a front elevation (b) of a bulb-shaped LED light source 100.
• FIG. 2 is a diagram showing mode of embodiment 1, being a diagram showing the light distribution characteristics of a bulb-shaped LED light source.
• FIG. 6 is a diagram showing the design parameters and evaluation results for comparative examples 1 to 7 and embodiments 1 to 4.
• FIG. 7 is a cross sectional view of a conventional LED bulb 200.
• Figure 8 is a diagram defining the light distribution angle of an LED element.
• Figure 1 to Figure 6 are diagrams showing mode of embodiment 1, where Figure 1 is a side elevation (a) and a front elevation (b) of a bulb-shaped LED light source 100;
• Figure 2 is a diagram showing the light distribution characteristics of a bulb-shaped LED light source;
• Figure 6 is a diagram showing the design parameters and evaluation results for comparative examples 1 to 7 and embodiments 1 to 4.
• the bulb-shaped LED light source 100 is provided with a metallic heat dissipation component 2 which is provided at one end with a metal cap 1 and which widens in a trumpet shape toward an opening at the other end. It comprises the heat dissipation component 2, an outer tube globe 5 having a light diffusing layer 6 on its inner surface and fitted to the opening of the cover 2, a substrate 3 provided inside a substantially spherical body 7 formed from the heat dissipation component 2 and the outer tube globe 5, and LED elements 4 mounted onto the outer surface of the substrate 3 facing the outer tube globe 5.
• the bulb-shaped LED light source 100 in the present mode of embodiment has the following characteristics.
• the light source is LED elements 4 (light emitting diodes) .
• LED elements 4 light emitting diodes
• It has a bulb-shaped appearance (see Figure 1) .
• At least n (a natural number of four or more) LED elements 4 are arranged in a planar fashion on a substrate 3 within the outer tube globe 5.
• Each LED element 4 has a light distribution characteristic (light distribution angle) of at least 60° and 120° or less (see Figure 2 and Figure 8 for details of the light distribution angle) . It should be noted that with an LED element 4 of 120° or more, the light distribution angle is wide and the illuminating angle is too wide for a light source employing an outer tube globe 5, since although there is no serious problem relating to non-uniform brightness, on the other hand the losses at the outer tube globe 5 are large, the efficiency as a light source is low, and it is difficult to increase the directly-downward illumination intensity. (7) The light distribution areas of each of the LED elements 4, where the light is distributed over the inner surface of the outer tube globe 5, are arranged so as to overlap .
• the overlap includes a portion in which n light distribution areas overlap, and the portion in which n light distribution areas overlap constitutes at least 10% of the inner surface of the outer tube globe 5.
• the area not included in the light distribution area of any of the LED elements 4 (referred to as zero overlap hereinbelow) is less than 30% of the inner surface of the outer tube globe 5.
• n LED elements 4 Light emitted from n LED elements 4 generates a maximum overlap of n overlapping light distribution areas. Depending on the arrangement of the LED elements 4 and the selected light distribution angle, the maximum number of overlaps may be less than n.
• the distances between the LED elements 4 and the inner surface of the outer tube globe 5 only fall within an extremely limited range, and this cannot be a factor that causes a significant difference, so the luminance tends to depend on the number of overlapping light distribution areas rather than on differences in the distance from the LED elements 4 to the illuminated inner surface of the outer tube globe 5.
• the number n (n is a natural number) of LED elements 4 is at least four or more. As shown in Figure 3, if the number n of LED elements 4 is three, then LED elements 4 with an extremely wide light distribution angle are required, and thus losses within the outer tube globe 5 increase, and the luminous efficacy of the overall lamp (bulb-shaped LED light source 100) is unsatisfactory.
• n is preferably four or more.
• the illuminating angle is wide then it is easier to produce an n-overlap light distribution area, but on the other hand illumination losses inside the outer tube globe 5 increase, so a light distribution angle ( ⁇ in Figure 2) of 120° or less is preferable. Also, if the illuminating angle is too narrow then it is difficult to generate an n-overlap area, and so the light distribution angle is preferably at least 60°.
• Increasing the directly-downward illumination intensity is also an important design factor, and there should at least be an n- overlap light distribution area on the outer tube globe 5 on the center line of the lamp (bulb-shaped LED light source 100) .
• n-overlap light distribution area on the outer tube globe 5 occupies at least 10% of the whole.
• the LED elements 4 are arranged in positions on a concentric circle then non-uniform brightness becomes less noticeable on visual observation.
• LED elements 4 use was made of typical white LED elements comprising blue LEDs combined with yellow phosphor, with each element having an output of 1001m and a rated power consumption of 1W. Then, five types were prepared, the only difference between them being the light distribution angle, using light distribution angles of 30°, 60°, 90°, 120° and 150°, and one element was arranged at the center of the 55mm diameter printed substrate 3 shown in Figure 1, and in some cases a plurality of LED elements 4 were arranged on a concentric circle from the center of the substrate 3 in symmetrical positions around said element, and bulb-shaped LED lamps (bulb-shaped LED light sources 100) of a type with an E26 metal cap were manufactured by way of experiment, and a comparative evaluation was performed.
• bulb-shaped LED lamps bulb-shaped LED light sources 100
• the total luminous flux of the experimental lamps was measured using an integrating sphere and was presented as a relative value, where 100% is defined as the theoretical efficiency (unit: lm/W) when the outer tube transmittance is 0.9 and the number of LED elements 4 employed is n, given by: rated output 100 (lm/element) x n (elements) / n (W) x 0.9 (outer tube transmittance) .
• non-uniform luminance on the outer tube globe 5 is called the luminance uniformity ratio, and it is preferable for the luminance to be uniform across all points, but unlike a bulb-shaped fluorescent lamp having a fluorescent lamp as the light source, realistically a uniform luminance cannot be achieved on the outer tube globe 5 since the light sources are very small and have a high luminance, and also have a light distribution angle. The degree of satisfaction felt by the user varies depending on how uniform this can be made.
• the experimental lamps were lit with their bases upwards, and the illumination intensity lm below the lamp was measured using an illuminometer, and a value was obtained by dividing the measured illumination intensity by the total wattage of the lamp.
• a directly-downward illumination intensity of at least 10 (lx/W) is satisfactory.
• one LED element 4 was arranged in the middle of the substrate 5, but this need not necessarily be arranged in the middle. Further, the transmittance of the outer tube globe 5 is not limited to 90%, and the material may also be a resin rather than glass. The LED elements 4 were arranged on a concentric circle for the purposes of comparison.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Optics & Photonics (AREA)
• Non-Portable Lighting Devices Or Systems Thereof (AREA)
• Led Device Packages (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=45065882

Family Applications (1)

Country Status (4)

Cited By (1)

Families Citing this family (1)

Citations (5)

Family Cites Families (2)

• 2010
  • 2010-12-10 JP JP2010276083A patent/JP5628017B2/ja active Active
• 2011
  • 2011-11-23 WO PCT/EP2011/070826 patent/WO2012076339A1/en active Application Filing
  • 2011-11-23 EP EP11790589.3A patent/EP2649364B1/de active Active
  • 2011-11-23 CN CN201180060008.1A patent/CN103261778B/zh not_active Expired - Fee Related

Patent Citations (5)

Also Published As

Similar Documents

Legal Events