Patent Application
20120127733
The present invention relates to an illumination device, in particular to an illumination device provided with a semi-conductor light-emitting element such as a Light Emitting Diode (LED).
In the field of general illumination, the widespread use of conventional incandescent light bulbs is giving way to use of fluorescent lamps, which are energy efficient and have a longer life expectancy. In recent years, demand for even greater energy efficiency and life expectancy has spurred research and development of lamps that use an LED. In particular, development of compact LED lamps, which can be used directly in existing light bulb sockets, is progressing (see, for example, Patent Literature 1). The structure of a compact LED lamp according to conventional technology is described with reference to
As shown in
A groove 920b is formed at the upper surface 920a of the holder 920 to surround the LED module 910. A rim 970b of the globe 970 is inserted into the groove 920b, and a gap between the groove 920b and the globe 970 is packed with an adhesive 980. By allowing the adhesive 980 to harden, the holder 920 and the globe 970 bond.
However, resin material forming the adhesive deteriorates due to heat. Also, the holder reaches a high temperature due to heat produced by the LED module while the lamp is lit. As a result, the edge of the adhesive in contact with the holder may heat up, deteriorate, and detach from the holder. If the adhesive detaches from the holder, then in particular when the lamp is used in a vertical position (i.e. hanging), the globe may fall out of the holder.
One possible way of addressing this problem is a method to form a concavity in a side wall of the groove (see FIG. 8 of Patent Literature 2) and fill the concavity with the adhesive, so that even if the adhesive detaches from the holder, the adhesive will catch in the concavity so that the globe does not fall out of the holder, for example as in the fluorescent lamp recited in Patent Literature 2.
In this method, however, the weight of the globe is supported only by the part of the adhesive in the concavity. This produces sheer stress between the part of the adhesive in the concavity and the part of the adhesive outside of the concavity that is pulled by the weight of the globe, which may cause a crack to form in the adhesive. If a crack formed in the adhesive extends, the globe may end up falling out of the holder. Moreover, a compact LED lamp is anticipated to have a life expectancy of 20,000 hours or longer. This is far longer than the fluorescent bulb recited in Patent Literature 2, making the problem of the globe falling out of the holder, due to a crack in the adhesive, salient.
In light of the above problems, it is an object of the present invention to provide an illumination device that is better than a conventional configuration at preventing the globe from falling out of the holder.
An illumination device according to the present invention comprises: a holder with a top surface and a back surface; a light-emitting module mounted on the top surface of the holder; and a globe covering the light-emitting module, wherein the holder has a groove surrounding the light-emitting module at the top surface of the holder, with a rim of the globe inserted in the groove, along a side wall of the groove, a first location is close to an opening of the groove, a second location is closer to a bottom of the groove than the first location, and the second location is more recessed than the first location in a direction perpendicular to a direction of depth of the groove, and the groove has at least one through-hole at part of the bottom of the groove to connect to the back surface of the holder, the groove and the at least one through-hole being filled with adhesive.
In the illumination device with the above structure, the adhesive that fills the groove and the through-hole is hardened after having filled the concavity formed on the side wall from the first location to the second location and having passed through the through-hole to the back surface of the holder. For this reason, when a lamp is used in a vertical position, even if the adhesive detaches from the holder, the globe is prevented from falling out of the holder since the adhesive catches on the side wall and the back surface.
Moreover, since the weight of the globe is distributed between the adhesive part that fills the concavity of the side wall and the adhesive part that reaches the back surface, the burden of the weight of the globe on the adhesive part that fills the concavity of the side wall is reduced as compared to when only the adhesive part that fills the concavity of the side wall supports the weight of the globe. Therefore, this structure reduces the occurrence of cracks in the adhesive and prevents the globe from falling out due to cracks in the adhesive.
The illumination device according to the present invention is thus better than a conventional configuration at preventing the globe from falling out.
Embodiments of the present invention are described in detail with reference to the drawings.
The compact LED lamp 1 is provided with an LED module 10, a holder 20 on which the LED module 10 is mounted, an E screw base 40 attached to the opposite side of the holder 20 than the LED module 10, and a globe 70 covering the LED module 10.
The LED module 10 is fastened to a top surface 24a of the holder 20 by a pair of fasteners 15.
An annular groove 21 is formed in the holder 20 so as to surround the LED module 10. A tubular rim 70a of the globe 70 is inserted in the groove 21 and attached with adhesive.
In the holder 20, a plurality of through-holes 22 are formed on a bottom surface 24d of the groove 21 in a direction of length of the groove 21 at predetermined intervals.
The LED module 10 is formed by a substrate 11, a plurality of LED elements 12 mounted on the substrate 11, and a phosphor layer 13 formed to cover the LED elements 12.
The holder 20 is formed by a tubular portion 25 and a disc-shaped mount 24 inserted in the tubular portion 25.
An annular section along an outer edge of an upper surface, in the direction of the Z-axis, of the mount 24 is cut out. Since the mount 24 is inserted into the tubular portion 25, the cut out section of the mount 24 forms the groove 21. Each through-hole 22 connects the bottom surface 24d of this groove 21 to a back surface 24b of the mount 24.
The mount 24 and the tubular portion 25 are formed with, for example, a metal such as an aluminum alloy and function as a heatsink for dissipating heat produced by the LED module 10.
A resin case 60 is disposed in the inside of the tubular portion 25, and a lighting circuit 50 for lighting the LED elements 12 is contained in an inner space of the resin case 60.
The resin case 60 provides insulation between the lighting circuit 50 and the mount 24/tubular portion 25. The resin case 60 is composed of a tubular portion 61 and a cap 62 covering an opening of the tubular portion 61. Note that
The lighting circuit 50 has a lighting circuit substrate 51 and a plurality of electronic components mounted on the lighting circuit substrate 51. The lighting circuit substrate 51 is electrically connected to the LED module 10 and the base 40 by a lead wire.
The globe 70 is composed of, for example, soda glass or heat-resistant transparent resin and allows light emitted from the LED module 10 through to the outside of the lamp. The tubular rim 70a of the globe 70 is inserted in the groove 21 and is bonded to the holder 20 by adhesive 80, such as silicone adhesive, that is packed in the groove 21 and allowed to harden.
The base 40 is attached to the tubular portion 25 via a resin coupling member 30.
The coupling member 30 and the resin case 60 are composed of, for example, Poly Buthylene Terephthalete (PBT), Poly Ether Sulfone (PES), Poly Ethylene Terephthalete (PET), etc.
From an edge D1 (first location) to an edge D2 (second location), a side wall 24c of the groove 21 is recessed in an inverted tapered shape, slanting in a direction perpendicular to the depth direction (Z-axis) of the groove 21.
In
The groove 21 includes a region 26 between the side wall 24c and a line extending vertically from the edge D1 of the side wall 24c to the bottom surface 24d.
The adhesive 80 fills the region 26 of the groove 21 (adhesive part 81) and has hardened after flowing from the bottom surface 24d of the groove 21 through each through-hole 22 to reach the back surface 24b (adhesive part 82).
Even if the compact LED lamp 1 with the above structure is used in a vertical position, the globe 70 will not fall out of the holder 20, since the holder 20 and the globe 70 are bonded with the adhesive 80. Furthermore, even if the adhesive 80 deteriorates along the side in contact with the holder 20, which reaches a high temperature due to heat from the LED module 10, the globe 70 is prevented from falling out of the holder 20. This is because the adhesive part 81 catches along the side wall 24c, since the side wall 24c is an inverted tapered shape, and because the adhesive part 82 catches in an area of the back surface 24b surrounding the through-holes 22. The adhesive 80 easily heats up and deteriorates, and the side of the adhesive 80 in contact with the holder 20 deteriorates and detaches more easily than the side in contact with the globe 70. Therefore, this bonding structure is highly effective in preventing the globe from falling out.
Moreover, in the compact LED lamp 1, if the adhesive 80 detaches, the weight of the globe 70 is supported not only by the adhesive part 81 of the adhesive 80, but also by the adhesive part 82. This distributes the burden of supporting the weight of the globe 70 as compared to when the weight is supported only by the adhesive part 81. Accordingly, the burden on the adhesive part 81 for supporting the weight of the globe 70 is reduced, which reduces the occurrence of cracks in the adhesive 80.
Furthermore, in the compact LED lamp 1, since the side wall 24c is an inverted tapered shape, the area of the adhesive that catches on the side wall of the groove when the adhesive detaches from the side wall is greater as compared to the concavity in the side wall shown in FIG. 8 of Patent Literature 2. Accordingly, the burden per unit of area on the adhesive part 81 for supporting the weight of the globe 70 is reduced, which reduces the occurrence of cracks in the adhesive 80.
A cross section of the concavity in the side wall shown in FIG. 8 of Patent Literature 2 is rectangular, and when packing the groove with adhesive, it is difficult for the adhesive to fill the corners of the concavity, especially the corner in the ceiling of the concavity, and therefore it is easy for a space to form. By contrast, a cross section of the region 26 of the groove 21 formed on the inverted tapered side wall shown in
As described above, the compact LED lamp 1 reduces the occurrence of cracks in the adhesive 80 and is better than a conventional configuration at preventing the globe 70 from falling out of the holder 20.
Furthermore, by providing through-holes 22 in the compact LED lamp 1, the adhesive 80 and the holder 20 bond over an increased area, thus increasing bonding strength.
As shown in
The convexity 127 protrudes out from the side wall 124c by the opening of the groove 121 in a direction perpendicular to the depth direction (Z-axis) of the groove 121 and is formed along the entire length of the groove 121. Along the side wall 124c, a part D12 (second location) that is closer to the bottom surface 124d than the convexity 127 is at a location that is more recessed in a direction perpendicular to the Z-axis than a distal edge D11 (first location) of the convexity 127.
The groove 121 includes a region 126 between the side wall 124c and a line extending vertically from the distal edge D11 of the convexity 127 to the bottom surface 124d.
The adhesive 180 fills the region 126 of the groove 121 (adhesive part 181) and has hardened after flowing from the bottom surface 124d of the groove 121 through each through-hole 122 to reach the back surface 124b (adhesive part 182).
When the compact LED lamp 101 with the above structure is used in a vertical position, even if the adhesive 180 deteriorates along the side in contact with the holder 120, the globe 70 is prevented from falling out of the holder 120. This is because the side wall 124c includes the convexity 127, on which the adhesive part 181 catches, and also because the adhesive part 182 catches in an area of the back surface 124b surrounding the through-holes 122.
Moreover, in the compact LED lamp 101, if the adhesive 180 detaches, the weight of the globe 70 is supported not only by the adhesive part 181, but also by the adhesive part 182. This distributes the burden of supporting the weight of the globe 70. Therefore, this structure reduces the occurrence of cracks in the adhesive 180 and is better than a conventional configuration at preventing the globe 70 from falling out.
As shown in
From an edge D21 (first location) to an edge D22 (second location), a side wall 224c of the groove 221 is recessed in an inverted tapered shape, slanting in a direction perpendicular to the depth direction (Z-axis) of the groove 221.
The groove 221 includes a region 226 between the side wall 224c and a line extending vertically from the edge D21 of the side wall 224c to the bottom surface 224d.
The adhesive 280 fills the region 226 of the groove 221 (adhesive part 281) and has hardened.
When the compact LED lamp 201 with the above structure is used in a vertical position, even if the adhesive 280 deteriorates along the side in contact with the holder 220, the globe 70 is prevented from falling out of the holder 220. This is because the adhesive part 281 catches along the side wall 224c, since the side wall 224c is an inverted tapered shape.
Note that if the adhesive 280 in the compact LED lamp 201 detaches, the globe 70 is supported only by the adhesive part 281. However, since the side wall 224c is an inverted tapered shape, the burden per unit of area on the adhesive part 281 for supporting the weight of the globe 70 is reduced, and air is prevented from remaining in the groove 221. Therefore, this structure reduces the occurrence of cracks in the adhesive 280 and is better than a conventional configuration at preventing the globe 70 from falling out.
Since there is no need to form through-holes in the compact LED lamp 201, the burden and cost of manufacturing the lamp can be reduced. Whether or not to form through-holes in the holder can be determined in accordance with the specifications and use of the lamp.
As shown in
The fasteners 315 are attached so as to partially cover the groove 321 from above, extending beyond a top surface 324a of a mount 324.
The adhesive 380 is packed to a position contacting with a back side (lower side along the Z-axis) of the part of the fasteners 315 covering the opening of the groove 321 and has hardened after flowing from the bottom surface 324d of the groove 321 through each through-hole 322 to reach the back surface 324b (adhesive part 382).
When the compact LED lamp 301 with the above structure is used in a vertical position, even if the adhesive 380 deteriorates along the side in contact with the holder 320, the globe 70 is prevented from falling out of the holder 320. This is because an adhesive part 381, which is covered from above in the direction of the Z axis by the fasteners 315, catches on the fasteners 315, and also because the adhesive part 382 catches in an area of the back surface 324b surrounding the through-holes 322.
Moreover, in the compact LED lamp 301, if the adhesive 380 detaches, the weight of the globe 70 is supported not only by the adhesive part 381, but also by the adhesive part 382. This distributes the burden of supporting the weight of the globe 70. Therefore, this structure reduces the occurrence of cracks in the adhesive 380 and is better than a conventional configuration at preventing the globe 70 from falling out.
Since there is no need to process a side wall 324c of the groove 321 in the compact LED lamp 301 to form a recess, the burden and cost of manufacturing the holder 320 can be reduced.
The globe provided in the compact LED lamp in Embodiment 5 differs from Embodiment 1, whereas other structures are essentially the same. Specifically, Embodiment 5 differs from Embodiment 1 in that whereas the rim 70a of the globe 70 in Embodiment 1 is formed only by a tubular part, a rim 670a of the globe 670 in Embodiment 5 is composed of a tubular part 671 and an annular flange 672 provided on the tubular part 671. Note that for the sake of simplicity, constituent elements that are the same as the compact LED lamp 1 shown in
In the compact LED lamp 601 in Embodiment 5, as shown in
When the compact LED lamp 601 with the above structure is used in a vertical position, even if the adhesive 80 deteriorates along the side in contact with the holder 20 and detaches, the globe 670 is prevented from falling out of the holder 20. Additionally, even if the adhesive 80 further deteriorates and detaches from the globe 670, the flange 672 of the globe 670 catches on the adhesive part 83, preventing the globe 670 from falling out of the holder 20.
Furthermore, by providing the flange 672, the adhesive 80 and the globe 670 bond over an increased area, thus increasing bonding strength as compared to the globe 70 in Embodiment 1.
In Embodiment 5, since the flange 672 provided in the rim 670a of the globe 670 catches on the adhesive part 83 of the adhesive 80, the globe 670 is prevented from falling out. By contrast, a globe 770 according to Embodiment 6 differs in that an annular concavity 771 is provided along the outer periphery of a rim 770a. The concavity 771 is formed to catch on an adhesive part 84 of the adhesive 80 that fills the inside of the concavity 771, thus preventing the globe 770 from falling out. Note that for the sake of simplicity, constituent elements that are the same as the compact LED lamp 601 shown in
When the compact LED lamp 701 with the above structure is used in a vertical position, even if the adhesive 80 deteriorates along the side in contact with the holder 20 and detaches, the globe 770 is prevented from falling out of the holder 20. Additionally, even if the adhesive 80 further deteriorates and detaches from the globe 770, the concavity 771 of the globe 770 catches on the adhesive part 84, preventing the globe 770 from falling out of the holder 20.
Furthermore, by providing the concavity 771, the adhesive 80 and the globe 770 bond over an increased area, thus increasing bonding strength, as in Embodiment 5.
In Embodiment 7, a plurality of oval-shaped through-holes 871 are formed in a rim 870a of the globe 870 in a circumferential direction at predetermined intervals, passing through from the inner peripheral surface to the outer peripheral surface of the rim 870a. Adhesive parts 85 of the adhesive 80 fill the through-holes 871 and catch on the through-holes 871, preventing the globe 870 from falling out. Embodiment 7 differs from the globe 670 in Embodiment 5 in this respect. Note that for the sake of simplicity, constituent elements that are the same as the compact LED lamp 601 shown in
When the compact LED lamp 801 with the above structure is used in a vertical position, even if the adhesive 80 deteriorates along the side in contact with the holder 20 and detaches, the globe 870 is prevented from falling out of the holder 20. Additionally, even if the adhesive 80 further deteriorates and detaches from the globe 870, the through-holes 871 of the globe 870 catch on the adhesive parts 85, preventing the globe 870 from falling out of the holder 20.
Furthermore, by providing the through-holes 871, the adhesive 80 and the globe 870 bond over an increased area, thus increasing bonding strength, as in Embodiment 5.
The compact LED lamp according to the present invention has been described based on the Embodiments, but the present invention is not limited to these Embodiments.
For example, the following Modifications are possible. Note that for the sake of simplicity, in the description of the Modifications of the present invention, constituent elements that are the same as the compact LED lamp 1 shown in
<1>
(1) In a direction of depth, part of a side wall 504c of the holder 500 shown in
This is advantageous in that, when forming the side wall, it is easier to form only part of the side wall in the direction of depth in an inverted tapered shape, rather than the entire length of the side wall.
Furthermore, as shown in
(2) In contrast with the side wall 504c in
<2> In the holder according to Embodiments 1 through 3, the recess in the side wall is shown as being formed along the entire length of the groove, but the recess in the side wall may be formed on at least part of the groove in a direction of length, or at predetermined intervals in a direction of length of the groove.
Also, a plurality of recesses in the side wall may be arranged in the direction of depth of the groove. The structure of the side wall of the groove can thus be determined in accordance with the specifications or use of the lamp.
<3> In the holder according to Embodiments 1 through 3, a recess for catching on the adhesive is shown as being formed in the inner peripheral side wall of the groove, but the recess may be formed on the outer peripheral side wall of the groove.
Alternatively, recesses may be formed on both sides of the groove. For example, in the case of a dovetail shaped groove, the adhesive catches on both side walls. As compared to when the adhesive only catches on one side wall, the groove is more effectively prevented from falling out.
<4>
(1) In a holder 520 shown in
(2) In a holder 530 shown in
(3) In the Modifications shown in
<5> In the above Embodiments and Modifications, a structure has been described in which the mount and the tubular portion composing the holder are separate elements, but the mount and the tubular portion may be an integral part of the holder.
Also, a structure is possible in which the mount is composed of a separate first mount and second mount. In this structure, the first mount is attached to the tubular portion, and the second mount, on which the LED module is provided, is attached to a central region of the first mount. By thus structuring the mount with two elements, the groove, side wall, and through-holes can be formed more easily.
<6> The globe in Embodiments 5 through 7 may be formed from soda glass, but from the perspective of ease of processing, it is preferable to form the globe from, for example, heat-resistant transparent resin.
<7> In Embodiments 5 through 7, a structure has been described in which the globe is attached to the holder 20 according to Embodiment 1, but the present invention is not limited in this way. For example, the globe according to Embodiments 5 through 7 may be attached to the holder shown in Embodiments 2 through 4, or the holder shown in the Modifications (see
<8> In the globe 670 according to Embodiment 5, the annular flange 672 has been described as attached to the rim 670a, but the present invention is not limited in this way. For example, the flange need not be annular in shape, and one or more arc-shaped flanges may be provided along the periphery of the rim of the globe.
Furthermore, the flange 672 has been described as protruding in a direction perpendicular to the tubular part 671, but the flange 672 may protrude so as to slant downwards or upwards from the tubular part 671. Additionally, the flange may protrude towards the inside of the globe. The number, shape, size, arrangement, etc. of the flanges can be determined in accordance with the specifications and use of the lamp.
<9> The globe 770 according to Embodiment 6 has been described as being provided with the annular concavity 771, but the present invention is not limited in this way. For example, a concavity may be provided along part of the periphery of the rim of the globe, or a plurality of concavities may be provided at predetermined intervals along the periphery. The concavity may also be formed along the inner periphery of the rim of the globe. The number, shape, size, arrangement, etc. of the concavities can be determined in accordance with the specifications and use of the lamp.
<10> In the globe according to Embodiment 7, the plurality of through-holes 871 are formed at predetermined intervals (equal intervals) along the periphery of the rim 870a, but the through-holes are not limited in this way. A plurality of through-holes may be formed at differing intervals along the periphery. Furthermore, the shape of the through-holes is not limited to being rectangular as shown in
<11> In Embodiment 1, the lighting circuit 50 is contained in the resin case 60, but the lighting circuit 50 need not be contained in the resin case 60. As long as insulation can be provided between the lighting circuit and the holder, the structure of the insulation can be determined in accordance with the specifications and use of the lamp.
For example, when not using a resin case, a mount may be provided along the inner circumference of the tubular portion 25, and the lighting circuit substrate 51 may be attached to this mount with an insulating film made of resin therebetween. Furthermore, by filling the space between the lighting circuit substrate 51 and the mount 24 with resin material and covering the lighting circuit substrate 51 with resin material, the insulation properties between the lighting circuit substrate 51 and the mount 24 can be improved.
The present invention can be widely used in general illumination.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-154998 | Jun 2009 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2010/003831 | 6/9/2010 | WO | 00 | 12/5/2011 |
