LED lamp

An LED lamp (A1) includes a plurality of LEDs (2), a retainer (1) on which the light LEDs (2) are mounted, and a wiring pattern formed on the retainer (1) and electrically connected to the LEDs (2). The retainer (1) includes a plurality of substrates (11, 12, 15). Of the plurality of substrates (11, 12, 15), two adjacent substrates (11, 12) are connected to each other by a pair of bendable connection members (32a, 32b). The two substrates (11, 12) are arranged in such a manner that their normal line directions differ from each other.

TECHNICAL FIELD

The present invention relates to an LED lamp that utilizes a light emitting diode (referred to as “LED” below) as the light source and that can be used as a substitute for an incandescent lamp or a fluorescent lamp.

FIG. 25is a perspective view showing an example of conventional LED lamp (see Patent Document 1, for example). The LED lamp X shown in the figure includes a disk-like substrate91, a plurality of LEDs92mounted on the disk-like substrate91, and a base93connected to the substrate91. The LED lamp X is structured such that the LEDs92can be turned on by mounting the base93to an existing light bulb socket designed for screwing-in a base of an incandescent lamp, for example.

In the LED lamp X, the LEDs92are mounted on a single, flat substrate91, which configuration allows only a limited area to be illuminated. Hence, the LED lamp X, when used in place of an incandescent lamp, may unduly leave a corner of the room badly lit.

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

The present invention has been proposed under the circumstances described above. It is therefore an object of the present invention to provide an LED lamp that is capable of illuminating a wider area.

Means for Solving the Problems

An LED lamp provided according to the present invention comprises a plurality of light emitting diodes, a retainer on which the light emitting diodes are mounted, and a wiring pattern formed on the retainer and electrically connected to the light emitting diodes. The retainer includes two mount surfaces that are adjacent to each other via a bent portion, and normal line directions of the two mount surfaces are oriented in different directions from each other.

In a preferred embodiment of the present invention, the LED lamp further comprises a support including a plurality of attachment surfaces whose normal line directions are different from each other. The retainer is attached to the support in such a manner that each of the two mount surfaces overlaps a respective one of the attachment surfaces.

Preferably, the attachment surfaces include a central attachment surface that overlaps one of the two mount surfaces. The support has a shape projecting in the normal line direction of the central attachment surface. The support includes a side surface that surrounds the central attachment surface as viewed in the normal line direction of the central attachment surface. Of the plurality of attachment surfaces, the attachment surface that overlaps the other one of the two mount surfaces is provided on the side surface.

More preferably, as the side surface proceeds away from the central attachment surface in the normal line direction of the central attachment surface, the side surface proceeds away from the central attachment surface in a direction perpendicular to the normal line direction of the central attachment surface.

More preferably, the central attachment surface is rectangular, and the side surface comprises a plurality of peripheral attachment surfaces that adjoin sides of the central attachment surface, respectively.

More preferably, the retainer comprises a plurality of separate substrates. The two mount surfaces are obverse surfaces of adjacent two of the plurality of substrates. The bent portion comprises a pair of bendable connection members connecting the two adjacent substrates. The paired connection members electrically connect the wiring patterns formed on the two substrates to each other.

In a preferred embodiment of the present invention, the retainer comprises a rectangular central substrate and a plurality of peripheral substrates separate from the central substrate and surrounding the central substrate. One of the two mount surfaces is an obverse surface of the central substrate, whereas the other one of the two mount surfaces is an obverse surface of the peripheral substrates. The bent portion comprises a pair of bendable connection members connecting the central substrate and each of the peripheral substrates. The paired connection members electrically connect the wiring pattern formed on the central substrate and the wiring pattern formed on the peripheral substrates to each other. The central substrate is attached to the central attachment surface, whereas the peripheral substrates are attached to the peripheral attachment surfaces.

In a preferred embodiment of the present invention, the retainer comprises a flexible wiring substrate. The two mount surfaces are part of an obverse surface of the flexible wiring substrate. The bent portion is formed by bending the flexible wiring substrate.

In a preferred embodiment of the present invention, the retainer comprises a flexible wiring substrate including a rectangular central mount surface that is one of the two mount surfaces and a plurality of peripheral mount surfaces that are the other one of the two mount surfaces and that surround the central mount surface. The bent portion is formed by bending between the peripheral mount surfaces and the central mount surface. The retainer is attached to the support in such a manner that the central mount surface is supported by the central attachment surface and the peripheral mount surfaces are supported by the peripheral attachment surfaces.

In another preferred embodiment of the present invention, the support is in the form of a frustum whose top surface is the central attachment surface. The retainer comprises a flexible wiring substrate including a disk-like central mount surface and a side mount surface surrounding the central mount surface. The bent portion is formed by bending a connection portion between the central mount surface and the side mount surface. The central mount surface and the central attachment surface overlap each other, whereas the side mount surface and the side surface overlap each other.

Preferably, the support is provided with a base for supplying electric power to the light emitting diodes, on an opposite side of the central attachment surface in the normal line direction of the central attachment surface.

Preferably, the support includes a reflective surface provided around the attachment surfaces.

More preferably, the support includes a columnar portion extending between the attachment surfaces and the reflective surface in a direction perpendicular to the reflective surface.

In a preferred embodiment of the present invention, the LED lamp further comprises a globe that includes an opening and houses the light emitting diodes.

More preferably, the inner surface of the globe includes a portion where a radius of curvature reduces as proceeding away from the opening.

More preferably, the globe includes a cylindrical portion and a dome portion connected to the cylindrical portion.

More preferably, the cylindrical portion is tapered.

In a preferred embodiment of the present invention, the LED lamp further comprises a globe that includes an opening and houses the light emitting diodes. The support is in the form of a frustum including a top surface positioned on an opposite side of the opening of the globe and one or a plurality of side surfaces surrounding the top surface. The globe includes an inner surface inclined in the same direction as a direction in which the one or a plurality of side surfaces adjacent thereto are inclined with respect to the top surface.

In another preferred embodiment of the present invention, the LED lamp includes a plurality of light emitting diodes, a foundation portion supporting the light emitting diodes, and a globe that includes an outer surface flush with an outer surface of the foundation portion and allows light emitted from the light emitting diodes to pass through.

In a preferred embodiment of the present invention, the LED lamp further comprises a retainer including a first surface on which at least any one of the light emitting diodes is mounted and a second surface which is oriented in a different direction from the first surface and on which at least any one of the light emitting diodes are mounted. The globe houses the light emitting diodes.

In a preferred embodiment of the present invention, the inner surface of the globe includes a portion where a radius of curvature reduces as proceeding away from the foundation portion.

In a preferred embodiment of the present invention, the globe includes a cylindrical portion including an outer surface that is flush with an outer surface of the foundation portion, and a dome portion connected to the cylindrical portion.

Preferably, the cylindrical portion is tapered.

More preferably, the outer surface of the foundation portion is smooth.

More preferably, the outer surface of the foundation portion is formed with minute irregularities.

In a preferred embodiment of the present invention, current flowing through the light emitting diodes is 20 to 25 mA.

In a preferred embodiment of the present invention, the LED lamp further comprises a support including a plurality of attachment surfaces oriented in different directions. The retainer is attached to the support in such a manner that each of the first and the second surfaces overlaps a respective one of the attachment surfaces.

In a preferred embodiment of the present invention, the retainer comprises a flexible wiring substrate. The first and the second surfaces comprise part of the obverse surface of the flexible substrate. The retainer is placed on the support, with the flexible wiring substrate bent.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1shows an LED lamp according to a first embodiment of the present invention. The LED lamp A1shown inFIG. 1includes a retainer1, sixty LED modules2mounted on the retainer1, four pairs of connection members32a,32b,33a,33b,34a,34b,35a,35b, a support4, a base5, two wirings6and a cover7.FIG. 2is a front view of the support4.FIG. 3is a plan view of the support4, as seen from above inFIG. 1.FIG. 4is a plan view of the retainer1in the state before it is attached to the support4. The base5of the LED lamp A1is attachable to an existing screw-type bulb socket so that the LED lamp A1can be used as a substitute for an incandescent lamp.

The retainer1comprises a central substrate11and four peripheral substrates12,13,14,15which are spaced apart from each other. As shown inFIG. 4, the retainer is formed with wiring patterns on the surface. The retainer1is further provided with a white protective layer (not shown) covering the wiring patterns. The central substrate11and four peripheral substrates12,13,14,15, which constitute the retainer1, are formed by cutting out of a single large plate-like substrate made of e.g. glass-fiber-reinforced epoxy resin.

Each LED module2incorporates an LED that may have a laminated structure made up of an n-type semiconductor layer, a p-type semiconductor layer, and an active layer sandwiched between these layers. The LED modules are incorporated in the wiring patterns on the retainer1to emit light.

As shown inFIG. 4, the central substrate11is rectangular in plan view and includes eight electrode pads112a,112b,113a,113b,114a,114b,115a,115b. The electrode pads112aand115bare electrically connected to each other, so are the electrode pads112band113a, the electrode pads113band114a, the electrode pads114band115a. The central substrate11has a mount surface11aon the obverse side, and twelve LED modules2are mounted on the mount surface11a. The wiring pattern on the central substrate11connects the electrode pad114b, the twelve LED modules2and the electrode pad115b. Specifically, this wiring pattern connects six pairs of parallel-connected LED modules2in series.

As shown inFIG. 4, the peripheral substrate12has a trapezoidal shape in plan view and is provided with three electrode pads12a,12b,12c. The peripheral substrate has a mount surface12aon the obverse side, on which twelve LED modules2are mounted. The electrode pads12aand12bare arranged along a side that is closer to the central substrate11. The electrode pad12cis arranged at an end of a side that is farther from the central substrate11. The wiring pattern on the peripheral substrate12connects the electrode pad12c, the twelve LED modules2and the electrode pad12b. Specifically, this wiring pattern connects six pairs of parallel-connected LED modules2in series. The electrode pad12ais connected to the electrode pad112aof the central substrate11via the connection means32a. The electrode pad12bis electrically connected to the electrode pad112bof the central substrate11via the connection means32b. One of the wirings6is connected to the electrode pad12c.

As shown inFIG. 4, the peripheral substrate13has a trapezoidal shape in plan view and is provided with two electrode pads13aand13b. The peripheral substrate has a mount surface on the obverse side, on which twelve LED modules2are mounted. The electrode pads13aand13bare arranged along a side that is closer to the central substrate11. The wiring pattern on the peripheral substrate13connects the electrode pad13a, the twelve LED modules2and the electrode pad13b. Specifically, this wiring pattern connects six pairs of parallel-connected LED modules2in series. The electrode pad13ais electrically connected to the electrode pad113aof the central substrate11via the connection means33a. The electrode pad13bis electrically connected to the electrode pad113bof the central substrate11via the connection means33b.

As shown inFIG. 4, the peripheral substrate14has a trapezoidal shape in plan view and is provided with two electrode pads14aand14b. The peripheral substrate has a mount surface on the obverse side, on which twelve LED modules2are mounted. The electrode pads14aand14bare arranged along a side that is closer to the central substrate11. The wiring pattern on the peripheral substrate14connects the electrode pad14a, the twelve LED modules2and the electrode pad14b. Specifically, this wiring pattern connects six pairs of parallel-connected LED modules2in series. The electrode pad19ais electrically connected to the electrode pad114aof the central substrate11via the connection means34a. The electrode pad14bis electrically connected to the electrode pad114bof the central substrate11via the connection means34b.

As shown inFIG. 4, the peripheral substrate15has a trapezoidal shape in plan view and is provided with three electrode pads15a,15b,15c. The peripheral substrate has a mount surface on the obverse side, on which twelve LED modules2are mounted. The electrode pads15aand15bare arranged along a side that is closer to the central substrate11. The electrode pad15cis arranged at an end of a side that is farther from the central substrate11. The wiring pattern on the peripheral substrate15connects the electrode pad15b, the twelve LED modules2and the electrode pad15c. Specifically, this wiring pattern connects six pairs of two parallel-connected LED modules2in series. The electrode pad15ais connected to the electrode pad115aof the central substrate11via the connection means35a. The electrode pad15bis electrically connected to the electrode pad115bof the central substrate11via the connection means35b. The other one of the wirings6is connected to the electrode pad15c.

The connection means32a,32b,33a,33b,34a,34b,35a,35bare made of e.g. solder mainly composed of Sn, Ag and Cu and bendable. The pair of connection means32aand32bconnect the central substrate11and the peripheral substrate12. The pair of connection means33aand33bconnect the central substrate11and the peripheral substrate13. The pair of connection means34aand34bconnect the central substrate11and the peripheral substrate14. The pair of connection means35aand35bconnect the central substrate11and the peripheral substrate15.

The support4is made of e.g. A1and includes a central attachment surface41, peripheral attachment surfaces42,43,44,45, a prism portion46, a reflective surface47and an outer casing48. To the lower end of the support4is mounted the base5. The reflective surface47and the outer casing48are formed with a through-hole49for guiding the two wirings6to the base5.

As shown inFIGS. 1 and 2, the central attachment surface41is rectangular and provided at the upper end of the support4. The normal line direction of the central attachment surface41is the vertically upward direction inFIGS. 1 and 2. As shown inFIGS. 1 and 2, all the peripheral attachment surfaces15,42,43,44,45are inclined with respect to the central attachment surface41. As shown inFIG. 3, the peripheral attachment surfaces42,43,44,45adjoin the four sides of the central attachment surface41and surround the central attachment surface. Each peripheral attachment surfaces42,43,44,45has a trapezoidal shape whose upper side is shorter and lower side is longer. Adjacent ones of the peripheral attachment surfaces42,43,44,45have a common side. The respective normal line directions of the peripheral attachment surfaces42,43,44,45are inclined with respect to the vertically upward direction and oriented in different directions from each other. The peripheral attachment surfaces42and44extend away from each other as proceeding downward, and also, the peripheral attachment surfaces43and45extend away from each other as proceeding downward.

The central substrate11is attached to the central attachment surface41by using e.g. a double-sided adhesive tape. The peripheral substrates12,13,14,15are attached to the peripheral attachment surfaces42,43,44,45by similarly using a double-sided adhesive tape, for example. Since the normal line directions of the central attachment surface41and the peripheral attachment surfaces42,43,44,45are different from each other, the normal line directions of the central substrate11and the peripheral substrates12,13,14,15, which are attached to these attachment surfaces, are also different from each other. Because of the inclination of the peripheral attachment surfaces42,43,44,45, more light from the LED modules2mounted on the peripheral substrates12,13,14,15is emitted upward than downward in the vertical direction.

The prism portion46connects the lower sides of the peripheral attachment surfaces42,43,44,45and the reflective surface47. As shown inFIG. 3, the reflective surface47is circular in plan view. The reflective surface47is provided for reflecting the light from the LED modules2upward.

The outer casing48has an outer surface that is painted white, and is designed to provide an appearance similar to that of an existing white light bulb when a cover7is attached to the outer casing.

One of the wirings6connected to the base5is connected to the electrode pad12c. The wiring pattern on the peripheral substrate12connects the electrode pad12cand the electrode pad12b. The electrode pad12bis electrically connected to the electrode pad13avia the electrode pads112b,113aand two connection means32b,33a. The wiring pattern on the peripheral substrate13connects the electrode pad13aand the electrode pad13b. The electrode pad13bis electrically connected to the electrode pad14avia the electrode pads113b,114aand two connection means33b,34a. The wiring pattern on the peripheral substrate14connects the electrode pad14aand the electrode pad14b. The electrode pad14bis electrically connected to the electrode pad114bvia the connection means34b. The wiring pattern on the central substrate11connects the electrode pad114band the electrode pad115b. The electrode pad115bis electrically connected to the electrode pad15bvia the connection means35b. The wiring pattern on the peripheral substrate15connects the electrode pad15band the electrode pad15c. The electrode pad15cis connected to the other one of the wirings6connected to the base5. With this arrangement, in the LED lamp A1, thirty pairs of parallel-connected LED modules2are arranged in series between the two wirings6. Thus, by mounting the base5to a socket for a light bulb, all the sixty LED modules2can be turned on.

The advantages of the LED lamp A1are described below.

According to the present embodiment, since the normal line directions of the central substrate11and the peripheral substrates12,13,14,15are different from each other, the directions of light emission from the LED module2mounted on the central substrate11and the peripheral substrates12,13,14,15are different from each other. Thus, the LED lamp A1illuminates a wider area.

According to the present embodiment, the brightness equivalent to a conventional 40 W incandescent lamp can be achieved at a power consumption of 8 W. Further, since the LED lamp A1is attachable to an existing socket for light bulbs, it can be readily used as a substitute for an incandescent lamp. The use of the LED lamp A1instead of an incandescent lamp achieves significant energy saving.

According to the present embodiment, before the retainer1is attached to the support4, whether or not the sixty LED modules2can be properly turned on can be checked by bringing test electrodes into contact with the electrode pads12cand15c. Thus, connection failure in the retainer1can be found before the retainer1is attached to the support4, which reduces waste in the manufacturing process. Thus, the LED lamp A1reduces the manufacturing cost.

According to the present embodiment, the LED modules2mounted on the central substrate11and the peripheral substrates12,13,14,15emit light mainly upward. Thus, blocking of light by the outer casing48and the resulting failure of light emission to the outside is unlikely to occur, which is desirable for increasing the amount of light emission from the LED lamp2.

According to the present embodiment, of the light emitted from the LED modules2, part of the light traveling downward is reflected upward by the reflective surface47. This is desirable for increasing the brightness of the LED lamp A1.

According to the present embodiment, the central attachment surface41and the peripheral attachment surfaces42,43,44,45are spaced apart from the reflective surface47and the base5due to the presence of the prism portion46. Thus, part of the light emitted from the LED modules2readily passes through the outside of the reflective surface47to travel downward of the LED lamp A1. This is desirable for increasing the illumination area of the LED lamp A1.

According to the present embodiment, the retainer1is cut out of a single large plate-like substrate, which is desirable for enhancing the productivity of the LED lamp A1.

An LED lamp according to a second embodiment of the present invention is described below. This LED lamp employs a flexible wiring substrate8shown inFIG. 4, instead of the retainer1of the LED lamp A1. The structures of other parts are the same as those of the foregoing LED lamp, and the illustration and description of these are omitted. The flexible wiring substrate8shown inFIG. 4includes a central mount surface81and four peripheral mount surfaces82,83,84,85, on which sixty LED modules2are mounted. As shown inFIG. 4, the wiring pattern on the flexible wiring substrate8is designed such that thirty pairs of parallel-connected LED modules2are arranged in series between the electrode pad82aand the electrode pad82b. The flexible wiring substrate8is designed to be attached to the support4by bending at a bent portion9between the central mount surface81and each of the peripheral mount surfaces82,83,84,85. Specifically, the central mount surface81is attached to the central attachment surface41, and the peripheral mount surfaces82,83,84,85are attached to the peripheral attachment surfaces42,43,44,45.

The use of the flexible wiring substrate8also provides an LED lamp that is capable of illuminating a wide area, similarly to the LED lamp using the retainer1. Unlike the retainer1, the flexible wiring substrate8does not need to use a connection member, so that the manufacturing process is simplified.

An LED lamp according to a third embodiment of the present invention is described below with reference toFIGS. 6-8. The LED lamp A2shown inFIG. 6employs the flexible wiring substrate8shown inFIG. 6instead of the retainer1of the LED lamp A1and also employs a support4shown inFIG. 7. The structures of other parts are the same as those of the LED lamp A1. InFIGS. 6-8, the elements that are identical or similar to those of the LED lamp A1are designated by the same reference signs as those used for the LED lamp A1, and the description is appropriately omitted. The support4shown inFIG. 8comprises a cylindrical portion46a, which is employed instead of the prism portion46, and a frustum portion placed on the cylindrical portion46a. The support4further includes a top surface41aand a side surface42aof the frustum portion.

As shown inFIG. 7, the flexible wiring substrate8of this embodiment includes a central mount surface86, a side mount surface87and a wiring pattern88. The flexible wiring substrate8is attached to the support4such that the central mount surface86overlaps the top surface41aand the side mount surface87overlaps the side surface92a. At that time, the connecting portion between the central mount surface86and the side mount surface87is bent to become a bent portion. The wiring pattern88is designed to electrically connect the LED modules2to each other. InFIG. 6, the illustration of the wiring pattern88and some of the LED modules2is omitted.

The use of this flexible wiring substrate8also allows the LED lamp to illuminate a wide area, similarly to an LED lamp using the retainer1. Unlike the retainer1, the flexible wiring substrate8does not need to use a connection member, so that the manufacturing process is simplified.

A fourth embodiment of the present invention is described below with reference toFIGS. 9-19.FIG. 9is a front view of the LED lamp according to the present embodiment.FIG. 10is an exploded perspective view of the LED lamp according to the present embodiment.FIG. 11is a sectional view of the LED lamp according to the present embodiment.FIG. 12is a right side view of the LED lamp according to the present embodiment.FIG. 13is a left side view of the LED lamp according to the present embodiment.FIG. 14is a rear view of the LED lamp according to the present embodiment.FIG. 15is a plan view of the LED lamp according to the present embodiment.FIG. 16is a bottom view of the LED lamp according to the present embodiment.

The LED lamp A4shown in these figures includes LED modules100, a retainer200, a support300, a foundation portion400, a base500, wirings610,620, a globe700and a power source unit800. The base500of the LED lamp A4is attachable to an existing screw-type bulb socket so that the LED lamp A4can be used as a substitute for an incandescent lamp.

Each LED module100incorporates an LED element that may have a laminated structure made up of an n-type semiconductor layer, a p-type semiconductor layer, and an active layer sandwiched between these semiconductor layers.

FIG. 17is a development view of the retainer200. For the convenience of understanding, the number of LED modules100shown in this figure is smaller than the number of LED modules100shown inFIG. 10, and the specific arrangement shown in this figure is slightly different from that shown inFIG. 10. In this embodiment, the retainer200is a flexible wiring substrate. The retainer200includes a top substrate210, a side substrate220, electrode pads230a,230b, and a wiring pattern230c. The top substrate210is circular and has an obverse surface210aand a reverse surface210b. On the obverse surface210aare mounted the LED modules100. The side substrate220is in the form of a side surface of a frustum and has an obverse surface220aand a reverse surface220b. On the obverse surface220aare mounted the LED modules100. The electrode pads230aand230bare formed on the obverse surface220aof the side substrate220. The wiring pattern230cis formed on the obverse surface210aof the top substrate210and the obverse surface220aof the side substrate220.

The obverse surface210aof the top substrate210is a central mount surface of the present invention. The obverse surface220aof the side substrate220is a side mount surface of the present invention.

FIG. 18shows the circuit configuration of the LED lamp according to the present embodiment. As shown inFIGS. 17 and 18, the wiring pattern230celectrically connects the LED modules100to each other. Further, the wiring pattern230celectrically connects two of the LED modules100to the electrode pad230a. In these figures, the LED modules100electrically connected to the electrode pad230aare designated as LED modules100a. Further, the wiring pattern230celectrically connects two of the LED modules100to the electrode pad230b. In these figures, the LED modules100electrically connected to the electrode pad230bare designated as LED modules100b. As clearly shown inFIG. 18, in the LED lamp A4, a plurality of pairs of parallel-connected LED modules100are connected in series from the electrode pad230ato the electrode pad230b.

FIG. 19is a perspective view of principal portions of the LED lamp A4shown inFIG. 10, and specifically, shows the support300, the foundation portion400, and the base500only. As shown inFIGS. 10,11and18, the support300includes a frustum portion310and a bottom plate portion320. The support300is made of a material with high heat dissipation efficiency, such as aluminum. The frustum portion310is hollow. The frustum portion310includes a top surface310aand a side surface310b. The top surface310ais a central attachment surface of the present invention and supports the top substrate210of the retainer200. Specifically, the top surface310aand the reverse surface210bof the top substrate210are bonded to each other with e.g. an adhesive. On the side surface310b, the side substrate220of the retainer200is placed. Specifically, the side surface310band the reverse surface220bof the side substrate220are bonded to each other with e.g. an adhesive. In the retainer200in a state attached to the frustum portion310, the boundary between the top substrate210and the side substrate220is bent to serve as a bent portion290. The bottom plate portion320is a collar-like member connected to the bottom edge of the frustum portion310. A rectangular hole330is formed at the boundary between the frustum portion310and the bottom plate portion320.

The wiring610is electrically connected to the electrode pad230a. The wiring610passes through the hole330and is guided into the frustum portion310. The wiring620is electrically connected to the electrode pad230b. The wiring620passes through the hole330and is guided into the frustum portion310.

The foundation portion400supports the support300and hence supports the LED modules100. The foundation portion400is made of e.g. aluminum. The foundation portion400is hollow. The outer surface400aof the foundation portion400is a smooth surface that is not formed with a fin for heat dissipation. The outer surface400amay have minute irregularities formed by embossing. When the outer surface400ahas such minute irregularities, the height difference among the irregularities may be e.g. 1 to 20 μm. The upper portion of the foundation portion400inFIG. 11tapers as proceeding upward inFIG. 11.

As shown inFIG. 11, the globe700is fitted in a gap defined between the foundation portion400and the bottom plate portion320. The globe700passes the light emitted from the LED modules100from the inner surface700ato the outer surface700b. In this embodiment, the globe700houses the LED modules100in it. The globe700is made of e.g. a translucent material. Examples of such a translucent material include polycarbonate. Either one or both of the inner surface700aand the outer surface700bmay have irregularities formed by embossing. The height difference among such irregularities, when formed, may be e.g. 1 to 20 μm.

The globe700includes a cylindrical portion710and a dome portion720. The cylindrical portion710tapers as proceeding upward inFIG. 11. The cylindrical portion710is tapered such that the outer surface700bof the globe700is connected flush with the outer surface400aof the foundation portion400. The dome portion720is connected to the cylindrical portion710. The inner surface700aincludes a portion where the curvature increases as proceeding upward in the figure. (That is, the inner surface700aincludes a portion where the radius of curvature reduces as proceeding upward in the figure.) In this embodiment, the curvature of the inner surface700achanges at the boundary between the substantially flat inner surface700aof the cylindrical portion710and the substantially spherical inner surface700aof the dome portion720.

The present invention includes the structure in which the cylindrical portion710is not tapered and the outer surface700bof the globe700and the outer surface400aof the foundation portion400are connected flush with each other.

As shown inFIG. 11, the power source unit800is housed in the foundation portion400. The power source unit800includes an AC/DC conversion unit. Electric power is supplied from the outside of the LED lamp4to the power source unit800via the base500. The power source unit800supplies electric power to the LED modules100via the wirings610and620. Thus, light is emitted from each of the LED modules100.

The advantages of the LED lamp A4are described below.

In the LED lamp A4, the top substrate210is placed on the top surface310aof the frustum portion310, and the side substrate220is placed on the side surface310b. The LED modules100are mounted on both of the obverse surface210aof the top substrate210and the obverse surface220aof the side substrate220. Since the top surface310aand the side surface310bof the frustum portion310are oriented in different directions from each other, the direction of light emission from the LED modules100mounted on the obverse surface210aand the direction of light emission from the LED modules100mounted on the obverse surface220aare different from each other. Thus, the LED lamp A4illuminates a wide area.

In the LED lamp A4, the LED modules100are mounted not only on the top substrate210but also on the side substrate220. Thus, as compared with the conventional LED lamp X in which the LEDs92are mounted on a flat substrate91, the LED lamp A4has a larger area for mounting the LED modules100. Thus, a larger number of LED modules100can be mounted in the LED lamp A4. Thus, a given luminance of light emission from the LED lamp A4can be achieved with reduced amount of current flowing through each of the LED modules100. Because of the characteristics of LED elements, when a current flowing through a single LED module100is reduced, the amount of heat generated from a single LED module100reduces at a greater rate than the rate of current reduction. Thus, the total amount of heat generated from the plurality of LED modules100reduces. Thus, the LED lamp A4is suitable for suppressing heat generation. In the LED lamp A4, the current caused to flow to a single LED module100is e.g. about 25 to 30 mA. This current value is 41 to 50% of the rated current.

In the LED lamp A4, by causing current to flow between the electrode pad230aand the electrode pad230b, whether or not the LED modules100include one that cannot be turned on properly can be checked easily. By carrying out this check before attaching the retainer200to the support300, the connection failure in the retainer200is found before the retainer200is attached to the support300. Thus, according to the LED lamp A4, the retainer200on which an LED module100that cannot be turned on is mounted is prevented from being attached to the support300. This is desirable for reducing waste in the process of manufacturing the LED lamp A4.

In the LED lamp A4, the inner surface700aof the globe700has a portion where the curvature increases as proceeding upward inFIG. 11. Of the inner surface700a, the portion close to the foundation portion400has a relatively small curvature. With this arrangement, a larger distance is secured between the LED modules100and the inner surface700athan when the inner surface700ais a perfectly spherical surface, for example. When the LED modules100are turned on and the LED lamp A4is seen from the outer surface700bside of the globe700, the brightness is not uniform in every portion of the outer surface700bif the distance between the LED modules100and the inner surface700ais small. In the LED lamp A4, however, since a large distance is secured between the LED modules100and the inner surface700aof the glove700, non-uniform brightness among portions of the outer surface700bis avoided.

In the present embodiment, the globe700is made up of the cylindrical portion710and the dome portion720. This arrangement is suitable for providing a large distance between the LED modules100and the inner surface700a. Thus, the LED lamp A4is suitable for avoiding non-uniform brightness among portions of the outer surface700b.

In the present embodiment, the LED modules100are housed in the globe700. This arrangement also contributes to the achievement of uniform distance between each of the LED modules100and the inner surface700a. This is suitable for avoiding non-uniform brightness among portions of the outer surface700b.

It is to be noted that the curvature of the inner surface700aof the globe700may change gradually as proceeding upward inFIG. 11, instead of changing at a boundary portion.

FIGS. 20-23show a fifth embodiment of the present invention. In these figures, the elements that are identical or similar to those of the fourth embodiment are designated by the same reference signs as those used for the fourth embodiment.

FIG. 20is a perspective view showing an LED lamp according to the present embodiment. The LED lamp A5shown in the figure includes LED modules100, a retainer200, a support300, a foundation portion400, a base500, wirings610,620, eight connection members63a,63b,64a,64b,65a,65b,66a,66b, a globe700and a power source unit incorporated in the foundation portion400. The LED lamp A5is different from the LED lamp A4mainly in the arrangement of the LED modules100, in that the retainer200is made up of a plurality of plate-like substrates made of a glass-fiber-reinforced epoxy resin, and in that the support300is in the form of a truncated pyramid. The specific structures of the foundation portion400, the base500, the globe700, and the power source unit of the LED lamp A5are the same as those of the LED lamp A4, so that description of these parts are omitted.FIG. 21is a front view of principal portions of the LED lamp A5shown inFIG. 20, and specifically shows the support300, the foundation portion400, and the base500only.FIG. 22is a plan view of the principal portions, as seen from above inFIG. 21.FIG. 23is a development view of the retainer200.

As shown inFIGS. 20 and 23, the retainer200includes a central substrate240, peripheral substrates250,260,270,280, eight electrode pads242a,242b,243a,243b,244a,244b,245a,245b, three electrode pads252a,252b,252c, two electrode pads262a,262b, two electrode pads272a,272b, three electrode pads282a,282b,282cand a wiring pattern230c.

The central substrate240is rectangular and made of e.g. glass-fiber-reinforced epoxy resin. The central substrate240includes an obverse surface240aand a reverse surface240b. On the obverse surface240aare mounted twelve LED modules100. The eight electrode pads242a,242b,243a,243b,244a,244b,295a,245band the wiring pattern230care formed on the obverse surface240a. The wiring pattern230celectrically connects the electrode pad242aand the electrode pad245bto each other, the electrode pad242band the electrode pad243ato each other, the electrode pad243band the electrode pad244ato each other, and the electrode pad244band the electrode pad245ato each other. The wiring pattern230con the central substrate240allows current to flow from the electrode pad244bto the electrode pad245bthrough the twelve LED modules100. The wiring pattern230con the central substrate240connects six pairs of parallel-connected LED modules100in series.

The peripheral substrate250has a trapezoidal shape and is made of e.g. glass-fiber-reinforced epoxy resin. The peripheral substrate250has an obverse surface250aand a reverse surface250b. On the obverse surface250aare mounted twelve LED modules100. The three electrode pads252a,252b,252cand the wiring pattern230care formed on the obverse surface250a. Specifically, the electrode pads252aand252bare formed on the obverse surface250aat a portion close to the central substrate240. The electrode pad252cis formed at an end of a side that is farther from the central substrate240. The wiring pattern230con the peripheral substrate250allows current to flow from the electrode pad252cto the electrode pad252bthrough the twelve LED modules100. The wiring pattern230con the peripheral substrate250connects six pairs of parallel-connected LED modules100in series.

The peripheral substrate260has a trapezoidal shape and is made of e.g. glass-fiber-reinforced epoxy resin. The peripheral substrate260has an obverse surface260aand a reverse surface260b. On the obverse surface260aare mounted twelve LED modules100. The two electrode pads262a,262band the wiring pattern230care formed on the obverse surface260a. Specifically, the electrode pads262aand262bare formed on the obverse surface260aat a portion close to the central substrate240. The wiring pattern230con the peripheral substrate260allows current to flow from the electrode pad262ato the electrode pad262bthrough the twelve LED modules100. The wiring pattern230con the peripheral substrate260connects six pairs of parallel-connected LED modules100in series.

The peripheral substrate270has a trapezoidal shape and is made of e.g. glass-fiber-reinforced epoxy resin. The peripheral substrate270has an obverse surface270aand a reverse surface270b. On the obverse surface270aare mounted twelve LED modules100. The two electrode pads272a,272band the wiring pattern230care formed on the obverse surface270a. Specifically, the electrode pads272aand272bare formed on the obverse surface270aat a portion close to the central substrate240. The wiring pattern230con the peripheral substrate270allows current to flow from the electrode pad272ato the electrode pad272bthrough the twelve LED modules100. The wiring pattern230con the peripheral substrate270connects six pairs of parallel-connected LED modules100in series.

The peripheral substrate280has a trapezoidal shape and is made of e.g. glass-fiber-reinforced epoxy resin. The peripheral substrate280has an obverse surface280aand a reverse surface280b. On the obverse surface280aare mounted twelve LED modules100. The three electrode pads282a,282b,282cand the wiring pattern230care formed on the obverse surface280a. Specifically, the electrode pads282aand282bare formed on the obverse surface280aat a portion close to the central substrate240. The electrode pad282cis formed at an end of a side that is farther from the central substrate240. The wiring pattern230con the peripheral substrate280allows current to flow from the electrode pad282bto the electrode pad282cthrough the twelve LED modules100. The wiring pattern230con the peripheral substrate280connects six pairs of parallel-connected LED modules100in series.

The obverse surfaces240a,250a,260a,270aand280aserve as a mount surface of the present invention.

The connection members63a,63b,64a,64b,65a,65b,66a,66bare made of e.g. solder mainly composed of Sn, Ag and Cu and bendable. The connection member63aelectrically connects the electrode pad242aand the electrode pad252a. The connection member63belectrically connects the electrode pad242band the electrode pad252b. The pair of connection members63aand63bconnects the central substrate240and the peripheral substrate250. It is to be noted that the electrode pad242aand the electrode pad252ado not need to be electrically connected to each other. However, the connection between the electrode pad242aand the electrode pad252aby the connection member63astrengthens the joint between the central substrate240and the peripheral substrate250.

The connection member64aelectrically connects the electrode pad243aand the electrode pad262a. The connection member64belectrically connects the electrode pad243band the electrode pad262b. The pair of connection members64aand64bconnects the central substrate240and the peripheral substrate260.

The connection member65aelectrically connects the electrode pad249aand the electrode pad272a. The connection member65belectrically connects the electrode pad244band the electrode pad272b. The pair of connection members65aand65bconnects the central substrate240and the peripheral substrate270.

The connection member66aelectrically connects the electrode pad245aand the electrode pad282a. The connection member66belectrically connects the electrode pad245band the electrode pad282b. The pair of connection members66aand66bconnects the central substrate240and the peripheral substrate280. It is to be noted that the electrode pad245aand the electrode pad282ado not need to be electrically connected to each other. However, the connection between the electrode pad245aand the electrode pad282aby the connection member66astrengthens the joint between the central substrate240and the peripheral substrate280.

In the LED lamp A5, current flows as follows. First, current flows from the electrode pad252cto the electrode pad252bthrough twelve LED modules100. Then, the current flows from the electrode pad252bto the electrode pad262athrough the connection member63b, the electrode pad242b, the wiring pattern230c, the electrode pad243aand the connection member64a. Then, the current flows from the electrode pad262ato the electrode pad262bthrough twelve LED modules100. Then, the current flows from the electrode pad262bto the electrode pad272athrough the connection member64b, the electrode pad243b, the wiring pattern230c, the electrode pad244aand the connection member65a. Then, the current flows from the electrode pad272ato the electrode pad272bthrough twelve LED modules100. Then, the current flows from the electrode pad272bto the electrode pad245athrough the connection member65b, the electrode pad244band the wiring pattern230c. Then, the current flows from the electrode pad245ato the electrode pad245bthrough twelve LED modules100. Then, the current flows from the electrode pad245bto the electrode pad282bthrough the connection member66b. Then, the current flows from the electrode pad282bto the electrode pad282cthrough twelve LED modules100.

In the LED lamp A5, similarly to the LED lamp A4, a plurality of pairs of parallel-connected LED modules100are connected in series.

As shown inFIGS. 20-22, the support300includes a truncated pyramidal portion350and a bottom plate portion320. The support300is made of a material with high heat dissipation efficiency, such as aluminum. The truncated pyramidal portion350is hollow. The truncated pyramidal portion350includes a top surface350aand four side surfaces350b,350c,350d,350e. On the top surface310ais placed the central substrate240of the retainer200. Specifically, the top surface310aand the reverse surface240bof the central substrate240are bonded to each other by using e.g. a double-sided adhesive tape. On the side surface350bis placed the peripheral substrate250of the retainer200. Specifically, the side surface350band the reverse surface250bof the peripheral substrate250are bonded to each other by using e.g. a double-sided adhesive tape. Similarly, on the side surface350cis placed the peripheral substrate260of the retainer200. On the side surface350dis placed the peripheral substrate270of the retainer200. On the side surface350eis placed the peripheral substrate280of the retainer200.

In this embodiment, the wiring610is connected to the electrode pad252c, whereas the wiring620is connected to the electrode pad282c.

Similarly to the LED lamp A4, the LED lamp A5can emit light by the supply of electric power from outside of the LED lamp A5to the LED modules100via the base500.

Because of the same reasons as described above with respect to the LED lamp A4, the LED lamp A5can illuminate a wide area. Further, similarly to the LED lamp A4, the LED lamp A5is also suitable for suppressing heat generation.

The retainer200can be formed by cutting out of a single large substrate. This is desirable for enhancing the productivity of the LED lamp A5.

FIG. 24shows a sixth embodiment of the present invention. In the figure, the elements that are identical or similar to those of the fifth embodiment are designated by the same reference signs as those used for the fifth embodiment.

The LED lamp illustrated in the figure is different from the LED lamp A5of the fifth embodiment in that a flexible substrate is employed as the retainer200. The use of a flexible substrate as the retainer200eliminates the need for connecting the central substrate240and each of the peripheral substrates250-280by using a connection member, and the central substrate240and each of the peripheral substrates250,260,270,280directly connect with each other. In the retainer200in a state placed on the support300shown inFIG. 20, the boundary between the central substrate240and each of the peripheral substrates250-280is bent to serve as bent portions290.

This arrangement provides the same advantages as described above with respect to the LED lamp A4.

The LED lamp according to the present invention is not limited to the foregoing embodiments. The specific structure of each part of the LED lamp according to the present invention may be varied in design in many ways. For instance, although the LED lamp A1for use as a substitute for an incandescent lamp is described in the embodiments, the present invention is also applicable to an LED lamp for use as a substitute for a straight-tube fluorescent lamp.

An additional LED module may be mounted on the reflective surface47to increase the amount of light.