Light-Emitting Device and Luminaire

To improve an angular color difference and emit uniform illumination light. According to an embodiment, a light-emitting device in an embodiment includes a light-emitting module (15). The light-emitting module (15) includes a substrate (21), a plurality of light-emitting elements (45) made of semiconductor, and a plurality of sealing members (54). The light-emitting elements (45) are disposed on the substrate (21). The sealing members (54) contain, as a main component, translucent resin mixed with a phosphor. The sealing members (54) are heaped up from the bottom surfaces thereof bonded on the substrate (21) and are each formed to bury a singularity or a plurality of the light-emitting elements (45). A ratio (H/D) of a diameter D of the bottom surfaces to height H of the heaps of the sealing members (54) is set to 0.22 to 1.0.

DESCRIPTION OF EMBODIMENTS

A light-emitting device according to a first embodiment includes a light-emitting module. The light-emitting module includes a substrate, a plurality of light-emitting elements made of semiconductor disposed on the substrate, and a plurality of sealing members containing, as a main component, translucent resin mixed with a phosphor, heaped up from the bottom surfaces thereof bonded on the substrate, and each formed to bury a singularity or a plurality of the light-emitting elements, a ratio (H/D) of a diameter D of the bottom surfaces to height H of the heaps being set to 0.22 to 1.0.

The light-emitting device in the first embodiment can be used as a light source mounted on, for example, a lighting fixture or a display device.

In the first embodiment, as the substrate, a single-layer or double-layer resin substrate can also be used. Further, in order to suppress a warp of the substrate and improve thermal radiation properties from the substrate, it is preferable to use a substrate having a configuration in which a metal foil of aluminum, iron, copper, or the like is laminated on the rear surface thereof.

In the first embodiment, representative examples of the light-emitting element made of semiconductor include an LED (light-emitting diode) chip. However, a semiconductor laser and the like can also be used. If the LED chip is used as the light-emitting element, a light emission color of the LED chip may be any one of red, green, and blue. LED chips having different light emission colors can also be used in combination.

In the first embodiment, as the resin contained as the main component of the sealing members that bury the light-emitting elements and the like, translucent and thermoplastic synthetic resin, for example, various kinds of epoxy resin or various kinds of silicone resin can be used. In the first embodiment, the number of the light-emitting elements buried by each of the sealing members is not limited to one and may be plural.

In the first embodiment, since the aspect ratio (H/D) of each of the sealing members, which seal the light-emitting element, is specified as explained above, a distance equal to or larger than 1 mm can be secured as a distance from the light-emitting element to positions on the surface of the sealing member. Therefore, it is possible to suppress an angular color difference without requiring a bank for preventing the sealing member from spreading before being hardened.

In a light-emitting device in a second embodiment, in the first embodiment, the sealing member is resin-based silicone resin and the hardness of the sealing member after formation is equal to or higher than 54 and equal to or lower than 94 in Shore hardness.

In the second embodiment, in the first embodiment, further, since the Shore hardness of the resin-based silicone resin forming the sealing member is in a range of (74±20), thixotropy until the hardening of the sealing members is improved. Consequently, the sealing member is suppressed from spreading before being hardened and decreasing in height. A distance equal to or larger than 1 mm can be secured as the distance from the light-emitting element to the positions on the surface of the sealing member. On the other hand, if the Shore hardness of the sealing member is lower than 54, the thixotropy decreases and it is difficult to secure a distance equal to or larger than 1 mm as the distance from the light-emitting element to the positions on the surface of the sealing member. If the Shore hardness of the sealing member exceeds 94, fluidity of the unhardened sealing member is lower than a specified value. Consequently, if the sealing member is formed by, for example, potting, an appropriate amount of the potting is difficult. Therefore, it is more likely that a potting failure is caused.

In a light-emitting device in a third embodiment, in the first embodiment, a wiring pattern is formed on the substrate. The light-emitting element is mounted on a mounting pad formed by a part of the wiring pattern. A wire connecting section adjacent to the mounting pad is formed on the substrate. The light-emitting device includes a wire that connects the mounting pad and the wire connecting section. One end of the wire connected to the light-emitting element is projected in the thickness direction of the light-emitting element to separate from the element. The other end of the wire connected to the wire connecting section is oblique. An intermediate portion of the wire between the one end and the other end is formed to be bent from the one end to be parallel to the light-emitting element. Projection height of the intermediate portion with respect to the light-emitting element is equal to or larger than 75 μm and equal to or smaller than 125 μm.

In the third embodiment, the wire is provided by wire bonding. A thin metallic wire, for example, a thin wire of gold can be suitably used. In the third embodiment, the description that the intermediate portion of the wire is formed to be bent from the one end of the wire to be parallel to the light-emitting element includes the meaning that the intermediate portion is parallel to the light-emitting element. However, actually, in some case, the intermediate portion is not completely parallel to the light-emitting element because of fluctuation in manufacturing. Such a fluctuating form is also included in the scope of the wording “to be parallel”. Therefore, in the third embodiment, it is possible to rephrase the description as “the intermediate portion of the wire is substantially parallel to the light-emitting element”. Therefore, a form in which the intermediate portion of the wire is obliquely bent from the one end of the wire and provided such that an angle formed by the one end and the intermediate portion is an acute angle is outside the scope of the wording.

Incidentally, the sealing member expands and contracts according to light emission and a stop of the light emission device. Stress is applied to the wire buried in the sealing member because of the expansion and contraction. However, in the third embodiment, the intermediate portion of the wire is formed to be bent from the one end of the wire connected to the light-emitting element to be parallel to the light-emitting element. At the same time, the projection height of the intermediate portion of the wire with respect to the light-emitting element is specified to be equal to or larger than 75 μm and equal to or smaller than 125 μm.

Consequently, the stress is reduced according to a reduction in the influence of the expansion and contraction of the sealing member on the wire. Therefore, it is possible to suppress the wire from being cut in a connecting section of the one end of the wire and the light-emitting element.

In a light-emitting device in a fourth embodiment, in the third embodiment, a protection member made of resin covering the wiring pattern is formed on the substrate. The mounting pad is covered with the sealing member. A groove is formed in at least one part of a peripheral portion of the mounting pad. A filled part of the protection member filled in the groove is bonded to the sealing member.

In the light-emitting device in the fourth embodiment, in the third embodiment, further, adhesiveness of the sealing member made of resin and the mounting pad made of metal covered with the sealing member is inferior to adhesiveness of resins. Consequently, it is likely that the sealing member peels. However, the filled part of the protection member made of resin filled in the groove in the peripheral portion of the mounting pad and the mounting pad are bonded. Therefore, holding performance of the sealing resin is improved and the peeling of the sealing resin can be suppressed.

A light-emitting device in a fifth embodiment further includes, in the first embodiment, a diffusive translucent pipe in which the light-emitting module is housed. If the pipe is made of resin in this embodiment, examples of the resin include polycarbonate resin.

In the fifth embodiment, in the first embodiment, further, it is possible to diffuse, with the pipe, light emitted from the light-emitting module and emit the light to the outside of the pipe as illumination light. Therefore, if the pipe is straight, the light-emitting device in the fifth embodiment can be implemented as a straight tube type lamp, which is a light source. If the pipe is annular, the light-emitting device in the fifth embodiment can be implemented as an annular lamp, which is a light source.

In a light-emitting device in a sixth embodiment, in the fifth embodiment, the translucency of the pipe is equal to or lower than 85% and the disposing pitch of the light-emitting elements is equal to or larger than 5 mm and equal to or smaller than 9 mm.

In the sixth embodiment, since the translucency of the pipe is equal to or lower than 85%, it is possible to make it less easy for the plurality of light-emitting elements from changing to light spots to be reflected on the pipe. If the disposing pitch of the light-emitting elements is smaller than 5 mm, the light-emitting elements are arranged at high density to be a main cause of an increase in costs. If the disposing pitch of the light-emitting elements exceeds 9 mm, the light-emitting elements are arranged at low density and further tend to be reflected on the pipe.

Therefore, in the sixth embodiment, in the fifth embodiment, further, it is possible to suppress, at low costs, the plurality of light-emitting elements from changing to light spots to be reflected on the pipe and flash the pipe at substantially uniform brightness.

A luminaire in a seventh embodiment is a luminaire including a luminaire main body, at least a pair of sockets attached to the luminaire main body, and a straight tube type light-emitting device including a diffusive translucent straight pipe, a light-emitting module formed long in an extending direction of the pipe and housed in the pipe, and caps attached to longitudinal direction both ends of the pipe, the light-emitting device being supported detachably to the sockets. The light-emitting module has a configuration explained below.

The light-emitting module includes a substrate, a plurality of light-emitting elements made of semiconductor disposed on the substrate, and a plurality of sealing members containing, as a main component, translucent resin mixed with a phosphor, heaped up from the bottom surfaces thereof bonded on the substrate, and each formed to bury a singularity or a plurality of the light-emitting elements, a ratio (H/D) of a diameter D of the bottom surfaces to height H of the heaps being set to 0.22 to 1.0.

The seventh embodiment is the luminaire including the light-emitting device as a straight tube type lamp, which is a light source. The light-emitting device includes the light-emitting module described in the first embodiment. Therefore, since a distance equal to or larger than 1 mm is secured as a distance from the light-emitting element to positions on the surface of the sealing member, an effect can be expected that it is possible to provide the luminaire that can improve an angular color difference and emit uniform illumination light.

First Embodiment

A light-emitting device in a first embodiment and a luminaire, for example, a lighting fixture including the light-emitting device as a light source are explained in detail below with reference toFIGS. 1 to 12.

Reference numeral1inFIGS. 1 and 2denotes a lighting fixture for one lamp. This lighting fixture1includes a fixture main body (a luminaire main body)2, a lighting circuit3, a pair of sockets4, and a reflecting member5and includes, as a light-emitting device, for example, a straight tube type lamp11forming a light source.

The fixture main body2shown inFIG. 2is made of, for example, a metal plate having an elongated shape. The fixture main body2extends in the front back direction of the paper surface on whichFIG. 2is drawn. The fixture main body2is fixed to, for example, an indoor ceiling using a not-shown plurality of screws.

The lighting circuit3is fixed to an intermediate portion in the longitudinal direction of the fixture main body2. The lighting circuit3is configured to receive a commercial alternating current power supply and generate a direct-current output. The lighting circuit3supplies the direct-current output to a below-mentioned lamp11.

Note that, a power supply terminal block, a plurality of member supporting fittings, a pair of socket supporting members, and the like, all of which are not shown in the figure, are attached to the fixture main body2. A power supply line of the commercial alternating-current power supply drawn in from the attic is connected to the power supply terminal block. Further, the power supply terminal block is electrically connected to the lighting circuit3and below-mentioned sockets4through a not-shown intra-fixture wire.

The sockets4are coupled to the socket supporting member and respectively disposed at longitudinal direction both ends of the fixture main body2. Both the sockets4are existing sockets matching, for example, caps13of a G13 type included in the below-mentioned lamp11. However, the sockets4are not limited to the existing sockets. Sockets of types matching a type of a cap can be used.

The sockets4include a not-shown pair of power supply terminals and the like to which below-mentioned terminal pins13aand13bare connected. In order to supply electric power to the below-mentioned lamp11, the intra-fixture wire is connected to only the power supply terminal of the socket4on one side. A wire for power supply is not connected to the other socket4.

The reflecting member5includes a bottom plate section5a,a side plate section5b,and a pair of end plates5c(only one of which is shown inFIG. 1) made of, for example, metal and is formed in a trough shape, the upper surface of which is opened.

The bottom plate section5ais flat. The side plate section5bis bent obliquely upward from width direction both ends of the bottom plate section5a.The pair of end plates5crespectively closes end face openings formed by the bottom plate section5aand ends in the longitudinal direction of the side plate section5b.A metal plate forming the bottom plate section5aand the side plate section5bis made of a color steel plate, the surface of which assumes a whitish color. Therefore, the surfaces of the bottom plate section5aand the side plate section5bare formed as reflection surfaces. Not-shown socket through-holes are respectively opened at longitudinal direction both ends of the bottom plate section5a.

The reflecting member5covers the fixture main body2and components attached to the fixture main body2. This state is retained by detachable decoration screws (seeFIG. 1)6. The decoration screws6can be turned by hand without using a tool. The decoration screws6are screwed into the member supporting metal piercing through the bottom plate section5aupward. The sockets4are projected to below the bottom plate section5athrough the socket through-holes.

The lighting fixture1is not limited to the lighting fixture for one lamp. The lighting fixture1can also be implemented as a lighting fixture for two lamps capable of supporting two lamps11explained below.

The lamp11detachably supported by the sockets4is explained below with reference toFIGS. 2 to 12.

The lamp11has dimensions and an outer diameter same as those of an existing fluorescent lamp. The lamp11includes a pipe12, the caps13attached to ends of the pipe12, a beam14, and at least one, for example, four light-emitting modules15. Note that, when the four light-emitting modules15are distinguished, the light-emitting modules15are illustrated and explained with suffixes a to d added thereto.

The pipe12is formed, for example, straight by a translucent resin material. As the resin material forming the pipe12, polycarbonate resin mixed with a diffusing material can be suitably used. The diffusion transmittance of the pipe12is 90% to 95%. As shown inFIG. 2, the pipe12has a pair of convex sections12aon the inner surface in a part, which is an upper part in a state of use of the pipe12.

The type of the caps13is G13. The caps13are respectively attached to the longitudinal direction both ends of the pipe12. The caps13are detachably connected to the sockets4. The lamp11supported by the sockets4by the connection is arranged right below the bottom plate section5aof the reflecting member5. A part of light emitted from the lamp11to the outside is made incident on the side plate section5bof the reflecting member5.

The respective caps13include terminal pins13aand13bas representatively shown inFIG. 2. The terminal pins13aand13bare projected to the outside of the caps13. The terminal pins13aand13bare electrically insulated from each other. The terminal pins13aand13bof the caps13are connected to the sockets4, whereby the lamp11is supported by the sockets4. In this supported state, electric power can be supplied to the lamp11by the power supply terminal in the socket4on one side and the terminal pins13aand13bset in contact with the power supply terminal.

As shown inFIG. 2, the beam14is housed in the pipe12. The beam14is a bar material excellent in mechanical strength and formed of, for example, an aluminum alloy to reduce weight. Longitudinal direction both ends of the beam14is coupled to the caps13while being electrically insulated therefrom. The beam14includes a plurality of substrate supporting sections14a(only one is shown inFIG. 2) formed in, for example, a rib shape.

As shown inFIG. 3, all the four light-emitting modules15ato15dare formed in an elongated rectangular shape and arranged to form a straight row. The length of the row is substantially equal to the total length of the beam14. The light-emitting modules15ato15dare fixed by not-shown screws screwed into the beam14through the light-emitting modules15ato15d.

Therefore, the light-emitting modules15ato15dare housed in the pipe12together with the beam14. In this supported state, width direction both ends of the light-emitting modules15ato15dare placed on the convex sections12aof the pipe12. Consequently, the light-emitting modules15ato15dare disposed substantially in parallel further on the upper side than a largest width section in the pipe12.

As shown inFIGS. 7 and 8, each of the light-emitting modules15includes a substrate21, a wiring pattern25, a protection member41, a plurality of light-emitting elements45, a first wire51, a second wire52, a sealing member54, and various electric components55to59.

The substrate21includes a base22, a metal foil23, and a cover layer24.

The base22is made of resin, for example, glass epoxy resin. A substrate (FR-4) made of the glass epoxy resin is low in thermal conductivity and relatively inexpensive. The base22may be formed by a glass composite substrate (CEM-3) or other synthetic resin materials.

As shown inFIGS. 7 and 8, the metal foil23is laminated on the rear surface of the substrate21and formed by, for example, a copper foil. The cover layer24is laminated over a peripheral portion rear surface of the metal foil23and the base22. The cover layer24is formed by a resist layer made of an insulating material, for example, synthetic resin. The substrate21is reinforced by the metal foil23and the cover layer24, which are laminated on the rear surface of the substrate21, not to warp.

As shown inFIGS. 7 and 8, the wiring pattern25is formed on the front surface of the base22(i.e., the front surface of the substrate21) in a three-layer structure. A first layer U is formed of copper plated on the front surface of the base22. A second layer M is plated on the first layer U and formed of nickel. A third layer T is plated on the second layer M and formed of silver.

Therefore, the surface of the wiring pattern25is made of silver. The third layer T made of silver forms a reflection surface. The total light reflectance of the third layer T is equal to or higher than 90%.

For example, white resist layer containing electrically insulative synthetic resin as a main component can be suitably used for the protection member41. The white resist layer functions as a reflection layer having high light reflectance. The protection member41is formed on the substrate21to cover the most part of the wiring pattern25. That is, the protection member41covers the wiring pattern25while leaving a plurality of parts of the wiring pattern25as mounting pads26. At the same time, the protection member41covers the wiring pattern25while leaving a plurality of parts of the wiring pattern25as wire connecting sections27. Further, the protection member41covers the wiring pattern25while leaving mounting parts of the below-mentioned electric components55to59.

At a stage when the protection member41is formed on the substrate21, the mounting pads26and the wire connecting sections27are formed in portions where the third layer T is exposed without being covered with the protection member41. As shown inFIG. 9, the mounting pads26are arranged in the longitudinal direction of the substrate21. The wire connecting sections27are respectively disposed in the vicinities of the mounting pads26while forming pairs with the mounting pads26. Therefore, the wire connecting sections27are arranged in the longitudinal direction of the substrate21at a disposing pitch same as a disposing pitch of the mounting pads26.

As shown inFIGS. 10 and 11, the mounting pad26has grooves26ato26din at least one part, for example, four parts in the peripheral portion of the mounting pad26. The grooves26ato26bare separated from one another by 90 degrees. The depths of the grooves26ato26bare 1/10 to ⅕ of a below-mentioned pad diameter D1. Further, the peripheral edge of the mounting pad26has arcuate edge portions26eat every 90 degrees. The edge portions26eare formed between the grooves adjacent to each other in the peripheral direction of the mounting pad26among the grooves26ato26d.

Since the mounting pad26has the grooves26ato26band the edge portions26e,the mounting pad26is formed in a substantial clover shape. The groove26ais larger than the other three grooves26bto26d.The wire connecting section27is disposed on the inside of the groove26a.The mounting pad26is formed symmetrically with respect to a straight line L (indicated by an alternate long and short dash line inFIG. 10) that passes the center of the mounting pad26and the wire connecting section27.

In this way, the mounting pad26is formed in the substantial clover shape and the wire connecting section27is provided in the groove26a.This can contribute to a reduction in a diameter D of the below-mentioned sealing member54. A pad diameter D1of the mounting pad26is, for example, 3.6 mm. The pad diameter D1is a dimension between the edge portions26elocated to form a pair across the center of the mounting pad26.

The protection member41is filled in the grooves26ato26b.Portions of the protection member41filled in the grooves26ato26bare referred to filled parts42(seeFIGS. 7 and 11). The filled parts42form convex portions projected toward the center of the mounting pad26. The filled parts42are projected from the surface of the third layer T with respect to the laminating direction of the wiring pattern25(seeFIG. 7). When the below-mentioned light-emitting element45is mounted on the mounting pad26, at least one of the filled parts42is used as a reference for deducing a mounting position of the light-emitting element45. The filled parts42are filled in the groove26aavoiding the wire connecting section27.

The protection member41is filled in the grooves26ato26b.The portions of the protection member41filled in the grooves26ato26bare referred to filled parts42(seeFIGS. 7 and 11). The filled parts42are projected from the surface of the third layer T with respect to the laminating direction of the wiring pattern25(seeFIG. 7). The filled parts42are filled in the groove26aavoiding the wire connecting section27.

The plurality of light-emitting elements45are formed by bare chips of LEDs. As the bare chips, for example, bare chips of LEDs that emit blue light are used. The bare chip of the LED includes a light-emitting layer on one surface of an element substrate made of sapphire. A plane shape of the bare chip is rectangular. As shown inFIG. 11, an element electrode45bforming an anode and an element electrode45aforming a cathode are provided side by side, for example, in the longitudinal direction of the bare chip of the LED.

In the light-emitting elements45, the other surface of the element substrate on the opposite side of the one surface is fixed to the mounting pads26, which are the reflection surfaces, using an adhesive46(seeFIGS. 7 and 8). In this case, the light-emitting elements45are respectively bonded on the mounting pads26with the arrangement of the element electrodes45aand45baligned with the arrangement of the grooves26aand26cof the mounting pad26. The light-emitting elements45mounted on the mounting pads26form a light-emitting element row arranged in the longitudinal direction of the substrate21(a direction in which the center axis extends). In the row, a disposing pitch of the light-emitting elements45is equal to or larger than 5 mm and equal to or smaller than 9 mm.

A bonding part of the light-emitting element45is preferably the center of the mounting pad26. Consequently, light emitted from the light-emitting element45and made incident on the mounting pad26can be reflected in a reflection surface region around the light-emitting element45.

In this case, the light made incident on the mounting pad26is more intense in a part closer to the light-emitting element45. The intense light can be reflected in the reflection surface region. The grooves26ato26dare out of the reflection surface region where the intense light is reflected. Therefore, the area of the surface (the reflection surface) of the mounting pad26is reduced by the grooves26ato26din the peripheral portion of the mounting pad26. However, this does not substantially reduce reflection performance of the mounting pad26and can be neglected.

Light emission of the light-emitting element45formed by the bare chip of the LED is realized by feeding a forward direction current to a p-n junction of a semiconductor. Therefore, the light-emitting element45is a solid-state element that directly converts electric energy into light. The light-emitting element45that emits light according to such a light emission principle has an energy saving effect compared with an incandescent lamp that causes a filament to glow at high temperature through energization and emits visible light through thermal radiation of the filament.

The adhesive46preferably has thermal resistance in obtaining durability of bonding and further has translucency in order to allow reflection even right under the light-emitting element45. As such an adhesive46, it is possible to suitably use a silicone resin-based adhesive.

The first wire51and the second wire52are made of a thin metallic wire, for example, a thin wire of gold and wired using a bonding machine.

As shown inFIG. 7, the first wire51is provided to electrically connect the light-emitting element45and the wiring pattern25. In this case, one end51aof the first wire is connected to the element electrode45aof the light-emitting element45. The other end51bof the first wire51is connected to the wire connecting section27of the wiring pattern25.

The one end51aof the first wire51is projected in a direction away from the light-emitting element45in the thickness direction of the light-emitting direction45. The wire connecting section27is closer to the substrate21side than the element electrodes45aand45bof the light-emitting element45with respect to the thickness direction of the light-emitting element45. The other end51bof the first wire51is obliquely connected to the wire connecting section27.

An intermediate portion51cof the first wire51is a part occupying a portion between the one end51aand the other end51b.As shown inFIG. 7, the intermediate portion51cis formed to be bent from the one end51ato be parallel to the light-emitting element45. Projection height h of the intermediate portion51cwith respect to the light-emitting element45is specified to be equal to or larger than 75 μm and equal to or smaller than 125 μm, preferably, equal to or larger than 60 μm and equal to or smaller than 100 μm. Consequently, the wire-bonded first wire51is wired with the height based on the light-emitting element45retained low (this wiring structure is referred to as low wiring loop in this specification).

The intermediate portion51cand the other end51bof the first wire51wired in this way extend in a direction orthogonal to a direction in which the light-emitting elements45form a row. Such wiring is realized by the explained arrangement of the light-emitting element45with respect to the mounting pad26. The length of the first wire51can be reduced by the wiring. Therefore, the costs of the first wire51can be reduced compared with the case in which the first wire51is arranged obliquely to the light-emitting element45in plan view.

The second wire52is provided to connect the light-emitting element45and the mounting pad26through wire bonding. In this case, one end of the second wire52is connected to the element electrode45bof the light-emitting element45by first bonding. The other end of the second wire52is connected to the mounting pad26by second bonding.

The sealing member54is formed by mixing appropriate amounts of a phosphor54band a filler54cin resin54a,which is a main component, as schematically shown inFIG. 12.

Resin-based silicone resin or hybrid silicone resin having translucency is used for the resin54a.The resin-based silicone resin and the hybrid silicone resin are harder than translucent silicone rubber because the resin-based silicone resin and the hybrid silicone resin have a three-dimensionally crosslinked structure.

The phosphor54bis excited by light emitted by the light-emitting element45and emits light having a color different from a color of light emitted by the light-emitting element45. In the first embodiment, since the light-emitting element45emits blue light, a yellow phosphor that emits, through the excitation, yellowish light having a complementary color relation with the blue light is used. Consequently, it is possible to emit white light as output light of the lamp11, which is the light-emitting device.

The sealing member54is formed on the substrate21to seal the mounting pad26, the wire connecting section27, the light-emitting element45, the first wire51, and the second wire52by burying the same. The sealing member54is formed by being dripped targeting the light-emitting element45in an unhardened state and thereafter subjected to heat treatment to be hardened. A dispenser or the like is used for the dripping (potting) of the sealing member54.

The hardened sealing members54are arranged on the substrate21at a predetermined interval in the longitudinal direction of the substrate21and disposed to form a sealing member row according to the row of the light-emitting elements45. The hardened sealing members54are bonded on the substrate21. That is, in the case of this embodiment, the bottom surface of the sealing member54is bonded to the mounting pad26of the wiring pattern25formed on the substrate21and the protection member41around the mounting pad26. The sealing members54are heaped up from the bottom surfaces thereof and are each formed to bury the light-emitting elements45. The sealing members54are formed in a dome shape or a Fuji mountain shape.

The diameter D (seeFIG. 7) of the sealing member54is specified to 1.0 to 1.4 times of the pad diameter D1. In the case of the first embodiment, the diameter D is 4.0 mm to 5.0 mm. Consequently, a part of the mounting pad26does not protrude from the sealing member54. At the same time, the sealing member54is not excessive with respect to the mounting pad26. It is possible to use a proper amount of the sealing member54while retaining a below-mentioned aspect ratio. Note that a frame or the like that surrounds the light-emitting element45and the like in order to specify the height H of the heap of the sealing member54from the bottom surface and the diameter D of the bottom surface is absent. Therefore, the diameter D and the height H of the sealing member54are controlled according to a dripping amount, hardness, and time until hardening of the sealing member54.

The height H of the heap of the sealing member54based on the light-emitting element45is equal to or larger than 1.0 mm. The aspect ratio of the sealing member54is set to 0.22 to 1.00 in order to secure the height H equal to or larger than 1.0 mm. The aspect ratio of the sealing member54is a ratio of the diameter D of the bottom surface of the sealing member54to the height H of the heap of the sealing member54that buries the light-emitting element45.

Further, a ratio of orthogonal diameters of the sealing member54is 0.55 to 1.00. The ratio of the orthogonal diameters indicates a ratio of diameters X and Y orthogonal to each other of the bottom surface of the sealing member54bonded to the substrate21as shown inFIG. 11. The diameter X is the diameter of the bottom surface arbitrarily drawn to pass through the center of the light-emitting element45. The diameter Y is the diameter of the bottom surface drawn to be orthogonal to the diameter X.

The electric component55shown in any one ofFIGS. 4 to 6is a capacitor. The electric component56is a connector. The electric component57is a rectifying diode. The electric component58is a resistor. The electric component59is an input connector.

The electric component55consisting of the capacitor is mounted in each of the four light-emitting modules15. The capacitor suppresses noise from being superimposed on the wiring patterns25of the light-emitting modules15to thereby prevent the light-emitting elements45to emit light by mistake.

As shown inFIG. 3, concerning the light-emitting modules15aand15ddisposed at longitudinal direction both ends of a module row formed by the four light-emitting modules15, the electric component56consisting of the connector is mounted at only one ends of the light-emitting modules15aand15d.Further, concerning the light-emitting modules15band15cdisposed between the light-emitting modules15aand15d,the electric component56is mounted at each of longitudinal direction both ends of the light-emitting modules15aand15d.The electric components56of the adjacent light-emitting modules15are connected by a not-shown electric wire extending across the electric components56. Consequently, the light-emitting modules15are electrically connected in series.

As shown inFIG. 5, all the electric components57to59are mounted at the other end of the light-emitting module15a.The electric component59consisting of the input connector is connected to the wiring pattern25of the light-emitting module15. The electric component59consisting of the input connector is connected to the wiring pattern52of the light-emitting module15. The not-shown electric wire connected to the electric component59is connected to each of the terminal pins13aand13bof the cap13disposed closer to the electric component59.

When the straight tube type lamp11having the above-mentioned configuration is supported by the sockets4of the lighting fixture1and electric power is supplied to the lamp11, each of the light-emitting elements45emits light. According to the light emission, white light emitted from the sealing member54is diffused by the pipe12and transmitted through the pipe12to be emitted to the outside. Consequently, a space below the lamp11is illuminated. At the same time, a part of the white light emitted from the pipe12is reflected by the side plate section5bof the reflecting member5and illuminates a space further on the upper side than the lamp11.

The mounting pad26of the light-emitting module15included in the lamp11forming such a light source of illumination is formed in a part of the wiring pattern25, the surface of which is made of silver. Consequently, the mounting pads26on which the light-emitting elements45are respectively mounted function as reflection surfaces of light.

At the same time, the sealing member54that buries the mounting pad26, the light-emitting element45, the wire connecting unit27, the first wire51, and the like and seals the same is formed of resin-based silicone resin. A crosslinked structure of the resin-based silicone resin is three-dimensional. Therefore, compared with silicone oil and silicone rubber, performance for transmitting gasses such as oxygen, water vapor, and the like is low. Incidentally, the oxygen permeability of the sealing member54is equal to or lower than 1200 cm3(m2·day·atm) and the water vapor permeability of the sealing member54is equal to or lower than 35 g/m2. The water vapor permeability is preferably equal to or lower than 20 g/m2.

The mounting pad26, the surface of which is the reflection layer of silver, is sealed by the resin-based silicone resin having the low gas permeability in this way. Consequently, deterioration in reflection performance due to discoloration of the mounting pad26caused by transmission of gas in the atmosphere through the sealing member54is suppressed. Therefore, it is possible to improve a luminous flux maintenance factor.

Incidentally, a luminous flux maintenance factor of the conventionally provided straight tube type LED lamp is about 70% in 40,000 hours. Compared with this, it has been confirmed by a test of the inventor that the lamp11in the first embodiment can improve the luminous flux maintenance factor to 94% in 40,000 hours.

Incidentally, the sealing member54expands and contracts every time lighting and extinguishing of the lamp11are repeated. According to the expansion and contraction, stress is applied to the first wire51buried by the sealing member54. On the other hand, the resin-based silicone resin has high hardness compared with silicone rubber. If the hardness of the sealing member54is high, the stress applied to the first wire51increases as the projection height h of the first wire51with respect to the light-emitting element45is higher.

However, the first wire51is wired to form the low wiring loop. That is, the intermediate portion51cof the first wire51is formed to be bent from the one end51aof the first wire51connected to the light-emitting element45to be parallel to the light-emitting element45. At the same time, the projection height h of the intermediate portion51cwith respect to the light-emitting element45is equal to or larger than 75 μm and equal to or smaller than 125 μm. In this way, the first wire51extending over the light-emitting element45and the wire connecting unit27is wired with the height thereof specified low.

Consequently, it is possible to reduce the stress applied to the first wire51according to the expansion and contraction of the sealing member54. Therefore, the first wire51is suppressed from being cut in a connecting section of the one end51aof the first wire51and the light-emitting element according to a heat cycle based on the lighting and extinguishing of the lamp11.

As explained above, with the lamp11in the first embodiment, it is possible to improve the luminous flux maintenance factor while suppressing disconnection of the first wire51connected to the light-emitting element45.

Further, the phosphor54bis mixed in the sealing member54included in the lamp11in the first embodiment. At the same time, the aspect ratio (H/D) representing a relation between the height H of the heap of the sealing member54based on the light-emitting element45and the diameter D of the bottom surface of the sealing member54is specified to 0.22 to 1.00. According to such specification of the aspect ratio, it is possible to secure a distance equal to or larger than 1 mm as the distance from the light-emitting element45to the positions on the surface of the sealing member54.

Consequently, an angular color difference is suppressed and it is possible to suppress color unevenness of parts such as the pipe12irradiated by light emitted from the sealing member54and the sideplate section5bof the reflecting member5irradiated by the light transmitted through the pipe12. In other words, it is possible to suppress a region irradiated in a bluish color by intense light of the light-emitting element45and a region irradiated in a yellowish color by intense light emitted from the phosphor54bfrom being mixed to be conspicuous.

Moreover, in the first embodiment, the hardness after formation of the sealing member54is specified to be equal to or higher than 54 and equal to or lower than 94 in Shore hardness. Consequently, it is possible to suppress the angular color difference.

That is, since the sealing member54contains the filler54c,the hardness of the sealing member54increases and thixotropy in the unhardened state of the sealing member54provided by potting is improved. Therefore, the potted sealing member is suppressed from spreading before being thereafter heated and hardened and decreasing in height H.

Therefore, the predetermined aspect ratio (H/D) is secured. It is possible to secure a distance equal to or larger than 1 mm as the distance from the light-emitting element45to the positions on the surface of the sealing member54.

Note that, on the other hand, if the filler54cis not mixed, the thixotropy is deteriorated. According to the deterioration in the thixotropy, the sealing member54easily spreads before being hardened and the height of the sealing member54decreases. Therefore, it is difficult to secure a distance equal to or larger than 1 mm as the distance from the light-emitting element45to the positions on the surface of the sealing member54. If the content of the filler54cis too high, fluidity of the unhardened sealing member is lower than a specified value. Therefore, an appropriate amount of the potting is difficult and it is more likely that a potting failure is caused.

Further, the grooves26ato26dare formed in the peripheral portion of the mounting pad26included in the lamp in the first embodiment. The filled parts42of the protection member41filled in the grooves26ato26dare covered with the sealing member54and bonded to the sealing member54. At the same time, the peripheral portion of the sealing member54is bonded to the protection member41.

In the first embodiment, adhesiveness of the sealing member54made of silicone resin and the surface made of silver of the mounting pad26covered with the sealing member54is inferior to adhesiveness of resins. Therefore, if the diameter D of the sealing member54is reduced, it is more likely that the sealing member54peels off the substrate21.

However, as explained above, the filled parts42of the protection member41made of resin in the grooves26ato26dof the mounting pad26are bonded to the mounting pad26made of resin. Consequently, holding performance of the sealing member54, which seals the mounting pad26and the like, to the substrate21is improved.

Therefore, even if the mounting pad26is reduced in diameter, peeling of the mounting pad26is suppressed. Therefore, it is possible to reduce an amount of use of the sealing member54. At the same time, the sealing member54is suitable for, for example, increasing disposing density of the mounting pads26and the light-emitting elements45.

Further, in the first embodiment, the pipe12made of resin having the diffusive translucency, in which the light-emitting module15is housed, diffuses light emitted from the light-emitting module15and emits the light to the outside as illumination light. Moreover, the pipe12is straight and the caps13are respectively attached to the longitudinal direction both ends of the pipe12. Therefore, the lamp11in the first embodiment can be implemented as a straight tube type lamp, which is a light source.

Moreover, the translucency of the pipe12is equal to or lower than 85% and the disposing pitch of the light-emitting elements45is equal to or larger than 5 mm and equal to or smaller than 9 mm.

If the translucency of the pipe12exceeds 85% and light permeability increases, the plurality of light-emitting elements45arranged in the longitudinal direction of the substrate21further tend to change to light dots to be reflected on the pipe12. If the disposing pitch of the light-emitting elements45is smaller than 5 mm, according to the disposing pitch, the light-emitting elements45are arranged at high density along the longitudinal direction of the substrate21. Therefore, the light-emitting elements45are a main cause of an increase in costs. Conversely, if the disposing pitch of the light-emitting elements45exceeds 9 mm, the light-emitting elements45are arranged at low density. Therefore, the light-emitting elements45further tend to be reflected on the pipe12.

Therefore, in the first embodiment in which the diffusive translucency of the pipe12and the disposing pitch of the light-emitting elements45are specified as explained above, it is possible to suppress, at low costs, the plurality of light-emitting elements45from changing to light spots to be reflected on the pipe12. At the same time, it is possible to flash the pipe12at substantially uniform brightness.

The first embodiment is configured as explained above. However, embodiments of the present invention are not limited to the first embodiment. For example, in the first embodiment, the light-emitting device is explained as the lamp including the caps. However, the light-emitting device can be implemented as a light-emitting device not including caps.