Patent Application
20110074269
The present invention claims priority under 35 U.S.C. ยง119 to Japanese Patent Application Nos. 2009-221638 and 2009-227474 filed on Sep. 25, 2009 and Sep. 30, 2009, respectively. The contents of these applications are incorporated herein by reference in their entirety.
Embodiments described herein relate generally to a self-ballasted lamp using semiconductor light-emitting elements, and lighting equipment using the self-ballasted lamp.
In a conventional self-ballasted lamp using LED chips as semiconductor light-emitting elements, a light-emitting module using the LED chips and a globe that covers the light-emitting module are attached to one end side of a metallic base body, a cap is attached to the other end side of the base body via an insulating member, and a lighting circuit is housed inside the insulating member.
When the self-ballasted lamp is turned on, heat generated by the LED chips is mainly conducted from a substrate to the base body and radiated into air from a surface of the base body which is exposed to the outside.
Additionally, as the light-emitting module, an SMD module mounting SMD (Surface Mount Device) packages with connection terminals, on which LED chips are loaded, on a substrate; a COB (Chip On Board) module in which a plurality of LED chips are closely arranged on a substrate; or the like are used.
The COB module has a single light-emitting portion provided and is capable of high-power light emission. However, since the plurality of LED chips are closely arranged in the light-emitting portion, the temperature of the LED chip easily rises. When the temperature of the LED chip rises excessively, the life of the LED chips is shortened and light output is reduced. Therefore, it is important to suppress a temperature rise of the LED chips by efficiently conducting heat generated by the LED chip to the base body and efficiently radiating the heat into air from the surface of the base body which is exposed to the outside.
Although, to efficiently radiate heat into air from the surface of the base body which is exposed to the outside, it is effective to increase the area of the surface of the base body which is exposed to the outside, and a problem arises that this leads to upsizing of the self-ballasted lamp and suitability of the lamp to lighting equipment using a general lighting lamp is reduced.
The present invention has been made in view of the above problems, and aims to provide a self-ballasted lamp which can secure sufficient radiation performance to suppress a temperature rise of a semiconductor light-emitting element without upsizing of the base body; and lighting equipment.
A self-ballasted lamp of the present embodiment includes a base body having a base body portion and a plurality of heat radiating fins provided on the circumference of the base body portion. A light-emitting module having semiconductor light-emitting elements and a globe that covers the light-emitting module are provided on one end side of the base body. A cap is provided on the other end side of the base body. A lighting circuit is housed between the base body and the cap. The lamp total length from the globe to the cap is 70 to 120 mm, the area of a surface of the base body which is exposed to the outside per 1 W of power charged to the light-emitting module is 20.5 to 24.9 cm2/W.
Next, Embodiment 1 will be described with reference to
In
The base body 12 is integrally formed of, for example, metal such as aluminum excellent in thermal conductivity, a base body portion 21 as a body portion is formed in a center region of the base body 12, and a plurality of heat radiating fins 22 are formed in the lamp axial direction on the circumference of the base body portion 21 so as to project radially around a lamp axis. Preferably, a surface of the substrate is subjected to alumite treatment.
On one end side of the base body portion 21, a columnar solid portion 23 is formed, and on the other end side thereof a cylindrical portion 24 opened toward the other end side is formed. A maximum diameter W1 of one end side of the base body portion 21 of the base body 12 is 55 to 65 mm, and a maximum diameter W2 of the other end side of the base body portion 21 is 25 to 30 mm.
The heat radiating fin 22 is obliquely formed so that the amount of projection of the fin 22 in a radial direction from the other end side to one end side of the base body 12 slowly increases. Additionally, the heat radiating fins 22 are radially formed in a circumferential direction of the base body 12 at approximately even intervals, and a gap 25 is formed between the heat radiating fins 22. The gaps 25 are opened toward the other end side and the periphery of the base body 12, and closed at one end side of the base body 12. An annular edge portion 26 continuing to the solid portion 23 is formed on the circumference of the solid portion 23 at one end side of the heat radiating fins 22 and gaps 25. Moreover, to improve radiation performance by the base body 12, a surface of the base body 12 is subjected to the alumite treatment.
An attachment face 27 with which and to which the light-emitting module 13 is brought into face-contact and attached is formed on a face of one end side of the base body 12, and a plurality of attachment holes 28, into which the light-emitting module 13 is screwed, is formed on the attachment face 27. On a circumferential region of one end side of the base body 12, an annular attachment portion 29 to which the globe 16 is attached is formed. An inclined face portion 30, of which one end side, the globe 16 side, has a small diameter, is formed at an outer circumference of the attachment portion 29.
On the base body portion 21 of the base body 12, a hole portion 31 for making the face of one end side of the base body 12 communicate with an inner face of the cylindrical portion 24, which constitutes the other end side of the base body 12, is formed at a position, which is located away from the center of the lamp axis in the lamp axial direction, a groove portion 32 is formed in the face of the one end side of the base body 12 so as to extend from one end side of the hole portion 31 to the circumferential region, and a wiring hole 33 is formed for connecting via wires the lighting circuit 17 to the light-emitting module 13 through the hole portion 31 and the groove portion 32.
When viewing the base body 12 from one end side thereof, the base body portion 21 has a volume more than that of the heat radiating fins 22, that is, a thermal capacity of the base body portion 21 capable of absorbing heat is more than that of the heat radiating fins 22.
The light-emitting module 13 has a quadrangular flat substrate 41 made of, for example, metal such as aluminum, or an insulating material such as ceramics or epoxy resin, a pair of wiring patterns 42 is formed on amounting face which is a face of one end side of the substrate 41, and a plurality of LED chips 43 as semiconductor light-emitting elements are closely arranged and mounted in a matrix on a center region of the mounting face. Moreover, in the case where the substrate 41 is made of metal, an insulating layer is formed on one face on which the LED chips 43 are mounted, and the wiring patterns 42 are formed on the insulating layer.
The light-emitting module 13 is a COB (Chip On Board) module, the mounting density of the LED chips 43 on the substrate 41 is 0.8 to 1.2 pcs/mm2, and 50 to 200 LED chips 43 are mounted. When the mounting density of the LED chips 43 on the substrate 41 is less than 0.8 pcs/mm2, this exceeds a limit of mounting precision of a machine which mounts the LED chips 43 on the substrate 41, heat is excessively concentrated and radiation performance deteriorates. When the mounting density is more than 1.2 pcs/mm2, it is impossible to increase the density of close arrangement of the LED chips 43, to downsize a light-emitting portion 47 and obtain a sufficient distance between the light-emitting portion 47 and an inner face of the globe 16. Therefore, unevenness of brightness is caused to the globe 16 when the lamp is turned on, and when the lamp is turned off, color of the light-emitting portion 47 is reflected in the globe 16, and an uncomfortable feeling with a color different from the original color of the globe 16 is easily sensed. Accordingly, the mounting density of the LED chips 43 on the substrate 41 is preferably 0.8 to 1.2 pcs/mm2. Additionally, when the number of LED chips 43 mounted is less than 50, necessary luminous flux is not obtained. On the other hand, when the number is more than 200, the light-emitting module 13 is upsized and the radiation performance of the LED chips 43 is lowered. Accordingly, 50 to 200 pieces of LED chips 43 are preferably mounted.
The pair of wiring patterns 42 forms a route for supplying power to the LED chips 43, a pair of electrode pads 44a for LED connection is formed at both sides of a mounting region of the LED chips 43, and the plurality of LED chips 43 are connected in series to the pair of electrode pads 44a by wire-bonding.
A connector 45 to be electrically connected to the wiring patterns 42 is disposed on an edge portion of the mounting face of the substrate 41 arranged on the grove portion 32 of the base body 12 with the light-emitting module 13 attached to the base body 12. Specifically, a pair of electrode pads 44b for connector connection is formed at ends of the pair of wiring patterns 42, and a pair of connector fixing pads 44c, which is electrically insulated from the wiring patterns 42, is formed at a position farther than the pair of electrode pads 44b from the LED chips 43. A pair of terminal portions for conduction (not shown), which is provided on a side face of the connector 45, is electrically connected to the pair of electrode pads 44b by solder 46b. Terminal portions for fixation (not shown), which are provided on both side faces of the connector 45, are fixed to the pair of connector fixing pads 44c by solder 46c respectively. The terminals for fixation do not electrically act on the connector 45, and mechanically support the connector 45.
As the LED chip 43, for example, an LED chip emitting blue light is used. A phosphor layer is formed so as to cover the plurality of LED chips 43 mounted on the substrate 41, the phosphor layer being obtained by mixing a yellow phosphor, which is excited by part of the blue light emitted from the LED chips 43 and radiates yellow light in, for example, transparent resin such as silicone resin. Thus, the light-emitting portion 47 is constituted by the LED chips 43 and the phosphor layer, a surface of the phosphor layer, which is a surface of the light-emitting portion 47, serves as a light-emitting face 48, and white-base light is radiated from the light-emitting face 48.
A plurality of insertion holes (not shown) are formed in the vicinity of four corners of the substrate 41, screws 49, which are inserted in the insertion holes respectively, are screwed into the attachment holes 28 of the base body 12 respectively, and thus a face of the other end side of the substrate 41 is brought into face-contact with and attached to the attachment face 27 which is the face of one end side of the base body portion 21 of the base body 12. Here, a thermally conductive material such as a sheet or grease excellent in thermal conductivity is interposed between the face of the other end side of the base body 41 and the attachment face 27 of the base body 12.
In a state where the substrate 41 is attached to the attachment face 27 of the base body 12, the center of the light-emitting face 48 of the light-emitting portion 47 is located on the center of the lamp axis and the light-emitting portion 47 of the light-emitting module 13 is located in a projection region (indicated by a dotted line in
In the state where the substrate 41 is attached to the attachment face 27 of the base body 12, the edge portion, on which the connector 45 is mounted, of the substrate 41 is located on the wiring hole 33, an end portion of the groove portion 32 of the wiring hole 33 is exposed and opened without being covered with the substrate 41.
The cover 14 is formed of, for example, an insulating material such as PBT resin in a cylindrical shape opened toward the other end side. An annular flange portion 51, which is interposed between the base body 12 and the cap 15 and insulates them from each other, is formed in an outer circumferential portion of the other end side of the cover 14. A wiring hole 52 coaxially communicating with the wiring hole 33 of the base body 12 is formed in a face of one end side of the cover 14.
The cap 15 is, for example, an E26 type cap and connectable to a socket for general lighting lamps, and has a shell 55 which is engaged with, caulked by and fixed to the cover 14; an insulating portion 56 provided at the other end side of the shell 55; and an eyelet 57 provided at a top portion of the insulating portion 56.
The globe 16 is formed of glass, synthetic resin or the like having light diffuseness in a dome shape so as to cover the light-emitting module 13. The other end side of the globe 16 is opened, and an engaging portion 60, which is engaged with an inner circumferential side of the attachment portion 29 of the base body 12 and fixed thereto by adhesive, is formed on an edge portion of the opening of the other end side of the globe 16.
The lighting circuit 17 is, for example, a circuit for supplying constant current to the LED chips 43 of the light-emitting module 13 and has a circuit substrate on which a plurality of circuit elements constituting the circuit are mounted, and the circuit substrate is housed and fixed in the cover 14. The shell 55 and eyelet 57 of the cap 15 are electrically connected to an input side of the lighting circuit 17 by a connection wire. A connection wire 64 having a connector 63 at its top end is connected to an output side of the lighting circuit 17. The connector 63 and the connection wire 64 are pulled out to one end side of the base body 12 through the wiring hole 52 of the cover 14 and the wiring hole 33 of the base body 12, and the connector 63 is connected to the connector 45 on the substrate 41. Moreover, the lighting circuit 17 is connected to the light-emitting module 13 before the light-emitting module 13 is screwed in the base body 12.
In the self-ballasted lamp 11 thus constituted, a lamp total length h from the globe 16 to the cap 15 is 70 to 120 mm, preferably, 98 to 110 mm, in the same size range as that of a general lighting lamp of 40 to 100 W. In the embodiment, the length h is about 109 mm, the area of the surface of the base body 12 which is exposed to the outside per 1 W of power charged to the light-emitting module 13 is 20.5 to 24.4 cm2/W. The area of the surface of the base body 12 which is exposed to the outside indicates the area of an outer peripheral face, which is not covered with the globe 16 and the cap 15, of the base body 12. In the embodiment, a power of 8.0 to 9.5 W is charged to the light-emitting module 13. An interval a between the heat radiating fins 22 is set to 7 to 10 mm.
When the self-ballasted lamp 11 is energized by attaching the cap 15 to the socket 72 of the lighting equipment 70, the lighting circuit 17 operates, power is supplied to the plurality of LED chips 43 of the light-emitting module 13, the LED chips 43 emit light and the light is diffused and emitted through the globe 16.
Heat generated when the plurality of LED chips 43 of the light-emitting module 13 are turned on is conducted to the substrate 41 and further conducted from the substrate 41 to the base body 12, and efficiently radiated into air from a surface of the base body portion 21 which is exposed to the outside of the base body 12 and surfaces of the plurality of heat radiating fins 22.
As shown in
On the other hand, generally, as the area of the surface of the base body 12 which is exposed to the outside per 1 W of power charged to the light-emitting module 13 becomes larger, the radiation performance is further increased. As a method for making the area of the surface of the base body 12 which is exposed to the outside large, it is considered that the gap 25 between the heat radiating fins 22 is narrowed and the number of heat radiating fins 22 is increased. However, when the gap 25 between the heat radiating fins 22 becomes too small, a convection current between heat radiating fins 22 is blocked and thus the radiation performance is lowered although the area of the surface of the base body 12 which is exposed to the outside is increased. Therefore, the area of the surface of the base body 12 which is exposed to the outside is required to increase without narrowing the gap 25 between the heat radiating fins 25 nor increasing the number of heat radiating fins 22. However, the substrate 12 is required to be upsized, the self-ballasted lamp 11 is upsized in accordance therewith, and suitability of the lamp 11 to the lighting equipment 70 for general lighting lamps is lowered. When only the surface area is made large without upsizing the substrate 12, for example, a substrate 12 can be manufactured, in which the area of the surface of the base body 12 which is exposed to the outside per 1 W of power charged to the light-emitting module 13 exceeds 24.4 cm2/W, by increasing the number of heat radiating fins 22. However, this case is undesirable, because a large number of portions, each of which has a thickness less than 1.0 mm, of the heat radiating fin 22 are generated and thermal conductivity of the heat radiating fin 22 is lowered. Therefore, in order to increase the area of a surface of the base body 12 which is exposed to the outside, when an experiment was performed to obtain an area of the surface of the base body 12 which is exposed to the outside so that sufficient suitability of the self-ballasted lamp 11 to the lighting equipment 70 for general lighting lamps can be obtained without making the substrate 12 too large, it was confirmed that the area of the surface of the base body 12 which is exposed to the outside per 1 W of power charged to the light-emitting module 13 is preferably 24.4 cm2/W or less.
Accordingly, when the area of the surface of the base body 12 which is exposed to the outside per 1 W of power charged to the light-emitting module 13 is 20.5 to 24.4 cm2/W, sufficient radiation performance can be secured, and the size of the substrate 12 does not become too large and is set in an optimum range.
As described above, according to the self-ballasted lamp 11 of the present embodiment, since the lamp total length h from the globe 16 to the cap 15 is 70 to 120 mm and the area of the surface of the base body 12 which is exposed to the outside per 1 W of power charged to the light-emitting module 13 is 20.5 to 24.4 cm2/W, sufficient radiation performance can be secured by making the area of the surface of the base body 12 which is exposed to the outside large, and an optimum range that the size of the base body 12 is not made too large can be regulated. That is, the base body 12 is not upsized and sufficient radiation performance for suppressing a temperature rise of the LED chip 43 can be secured.
When an experiment was performed to confirm a relationship between the gap 25 between the heat radiating fins 22 and the radiation performance, it was confirmed that, when the gap 25 between the heat radiating fins 22 is less than 7 mm, the convection current between the heat radiating fins 22 is blocked and the radiation performance is lowered although the surface area of the base body 12 is increased. On the other hand, when the gap 25 between the heat radiating fins 22 is more than 10 mm, the base body 12 is required to be upsized in order to secure a necessary surface area of the base body 12. Accordingly, 7 to 10 mm of the gap 25 between the heat radiating fins 22 is an optimum range that the convection current between the heat radiating fins 22 is not blocked and the area of the surface of the base body 12 which is exposed to the outside can be made large.
Since the light-emitting portion 97 of the light-emitting module 13 is arranged at a position farthest from the inner face of the globe 16, the light-emitting portion 47 is arranged at the center of one end side of the base body 12 and thermal conductivity from the light-emitting portion 47 to the base body 12 is increased, and the radiation performance can be improved. Additionally, compared with the case where the light-emitting portion 47 is arranged at a position deviating from the center of one end side of the base body 12, the unevenness of brightness of the globe 16 can be prevented when the lamp is turned on, and, when the lamp is turned off, an uncomfortable feeling with a color different from the original milky-white color of the globe 16 can be lowered, the uncomfortable feeling being caused in a manner that the color of the phosphor included in the light-emitting portion 47 is reflected in the globe 16.
When viewing the base body 12 from one end side, the base body portion 21 has a volume more than that of the heat radiating fins 22, that is, the thermal capacity of the base body portion 21 capable of absorbing heat is more than that of the heat radiating fins 22. Therefore, when the light-emitting portion 47 of the light-emitting module 13 is positioned in a region of one end side, preferably within the region of the base body portion 21, heat generated from the plurality of LED chips 43 can be efficiently and continuously absorbed by the base body portion 21 having a large thermal capacity. Thus, heat can be efficiently conducted to the base body portion 21 of the base body 12, thermal conductivity from the base body portion 21 to the heat radiating fins 22 is made excellent, the heat can be efficiently radiated by the heat radiating fins 22 to the outside, and the temperature rise of the LED chip 43 can be effectively suppressed.
Since the wiring hole 33 is formed by the hole portion 31 for making one end side and the other end side of the base body portion 21 of the base body 12 communicate with each other; and the groove portion 32 formed in the face of one end side of the base body 12 so as to extend from one end side of the hole portion 31 to the circumferential region of the base body 12, wiring connection between the lighting circuit 17 and the light-emitting module 13 can be easily performed while thermal conductivity from the light-emitting module 13 to the base body 12 is secured.
In particular, since the hole portion 31 of the wiring hole 33 is formed at a position deviating from the center of the base body portion 21, the heat generated from the LED chips 43 can be efficiently conducted to the center of the base body portion 21 even if the LED chips 43 of the light-emitting module 13 are arranged at a position corresponding to the center of the base body portion 21 in consideration of light distribution of the self-ballasted lamp 11.
The connector fixing pads 44c are formed at a position farther than the electrode pads 44b from the LED chips 93 on the substrate 91 of the light-emitting module 13, the terminal portions of the connector 45 are connected to the electrode pads 44b by the solder 46b respectively, and the terminal portions for fixation of the connector 95 are fixed to the connector fixing pads 44c by the solder 46c respectively. Thus, the solder 46b connecting the terminal portions of the connector 45 to the electrode pads 44b is more easily affected by the heat generated from the LED chips 43, compared with the solder 46c adhering the terminal portions for fixation of the connector 45 to the connector fixing pads 44c. Accordingly, when the LED chip 43 has trouble due to some cause and abnormally heats, the solder 46b connecting the terminal portions of the connector 45 to the electrode pads 44b melts sooner than the solder 46c fixing the terminal portions for fixation of the connector 45 to the connector fixing pads 44c, and the connector 45 is easily electrically opened.
Particularly, as described in the above embodiment, in a case where a great number of LED chips 43 are mounted and concentrated at high density, heat diffusion from the LED chip 43 has a direction from the light-emitting portion 47 to an outer periphery of the substrate 41, compared with a case where a plurality of SMD packages are dispersed and arranged on a substrate. Accordingly, influence of the heat from the LED chips 43 tends to depend on the positional relationship between the electrode pads 44b and the connector fixing pads 44c, and there is an advantage of being excellent in reproducibility of the above phenomenon.
When the connector 45 is electrically opened, energization to the LED chip 43 is blocked, the temperature of the LED chip 43 is lowered, melting of the solder 46c of the terminal portions for fixation of the connector 45 is reduced, and fixation of the connector 45 to the substrate 41 is difficult to lose. Consequently, even when the light-emitting module 13 drops off from the base body 12 due to some cause, dropping or detachment of the light-emitting module 13 can be reduced by the connection wire 64 via the connector 45. Even when the connection wire 64 has a surplus in length or fixation of the solder 46c to the terminal portions for fixation of the connector 45 is lost, it can be expected that electrical conduction to the light-emitting module 13 is blocked in advance. Thus, occurrence of trouble by detachment of the light-emitting module 13 can be reduced.
Next, Embodiment 2 is described with reference to
A self-ballasted lamp 11 of Embodiment 2 is a mini-krypton bulb type using an E17 type cap, although the self-ballasted lamp 11 of Embodiment 1 is an incandescent bulb type using the E26 type cap. The self-ballasted lamp 11 of Embodiment 2 has the same basic structure and layout as those of the self-ballasted lamp 11 of Embodiment 1.
The self-ballasted lamp 11 has a lamp total length h from a globe 16 to a cap 15 of approximately 72 mm, a maximum diameter W1 of one end side of a base body portion 21 of 42 to 45 mm, a maximum diameter. W2 of the other end side of the base body portion 21 of 15 to 20 mm, an interval a between heat radiating fins 22 of 7 to 10 mm, and a power charged to a light-emitting module 13 of 2.2 to 2.8 W. Also, in the case of the self-ballasted lamp 11, the area of a surface of the base body 12 which is exposed to the outside per 1 W of power charged to the light-emitting module 13 is 20.5 to 24.4 cm2/W.
Even in the mini-krypton bulb type self-ballasted lamp 11 thus using the E17 type cap, since the area of the surface of the base body 12 which is exposed to the outside per 1 W of power charged to the light-emitting module 13 is 20.5 to 24.4 cm2/W, sufficient radiation performance can be secured by making the area of the surface of the base body 12 which is exposed to the outside large, and the size of the base body 12 is not made too large and can be regulated within an optimum range. That is, the base body 12 is not upsized and radiation performance sufficient to suppress a temperature rise of the LED chip 43 can be secured.
Moreover, as the semiconductor light-emitting element, an EL (Electro Luminescence) element may be used in addition to the LED chip 43.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-221638 | Sep 2009 | JP | national |
| 2009-227474 | Sep 2009 | JP | national |
