EP2851608A1

EP2851608A1 - Led lamp

Info

Publication number: EP2851608A1
Application number: EP14275199.9A
Authority: EP
Inventors: Onn Fah Foo
Original assignee: Mass Technology HK Ltd
Current assignee: Mass Technology HK Ltd
Priority date: 2013-09-23
Filing date: 2014-09-23
Publication date: 2015-03-25
Also published as: CN203517389U

Abstract

The present invention relates to an LED lamp that can be a direct replacement for an incandescent lamp and comprises a light-pervious bulb shell (1), a lamp cap (7) for connection to a lamp holder, at least one LED substrate (2) arranged inside the bulb shell (1), a drive circuit (8) connected to the LED substrate (2) and the lamp cap (7), a plurality of LED chips mounted on the LED substrate (2) in a manner that the LED chips are located in the vicinity of an inner surface of the bulb shell (1) and emit light towards a plurality of different directions. The heat generated by the LED chips is transferred directly to the outside of the bulb shell through the nearby light-pervious bulb shell (1), and also dissipated by a heat sink mechanism via both heat conduction and heat convection, achieving increased heat dissipation efficiency with a simple structure.

Description

Technical Field of the Invention

The present invention relates to a LED lamp, in particular a LED lamp that comprises a novel heat dissipation system and can be a direct replacement for an incandescent lamp. The heat dissipation system fully utilizes a light-pervious bulb shell and cover means in combination for the heat dissipation, thereby allowing for a higher LED output power.

Background of the Invention

Nowadays LED lighting has gradually emerged as the mainstream lighting. It is known from the prior art that a small-size and light-weight LED lamp intended for a direct replacement for an incandescent lamp is produced by applying dedicated LED substrate strips in a bulb shell filled with a low-viscosity gas and using the surface of the bulb shell as a heat dissipater and a non-isolated and non-driven circuit. For instance, Chinese utility model patent number 201020617406.1 discloses a LED lamp that can be a direct replacement for an incandescent lamp and is used in inductive lamps, comprising a light-pervious bulb shell, a stem comprising an exhaust pipe, an electrical lead line and a support post, at least one LED lighting strip fixed to the support post of the stem, a driver and an electric connector, wherein electrodes of the LEDs are connected to the driver and the electrical connector through the electrical lead line of the stem so as to connect to external power supply; the light-pervious bulb shell and the stem are vacuum-sealed, and the bulb shell is filled with an inert gas having high thermal conductivity to dissipate heat and protect the LEDs. Although having a higher efficiency, a shape similar to that of a general incandescent lamp, and capable of being a direct replacement for an incandescent lamp, this type of LED lamp has a higher cost because it requires complex and expensive equipment to produce and the thermally conductive gas is needed to be filled in the bulb shell. Moreover, the heat of the LEDs cannot be effectively dissipated by using only the thermally conductive gas and the surface of the bulb shell, with a result of a lower output power of the LEDs. Other heat dissipation systems for LEDs can be found in the prior art, which, however, include complex and expensive cooling agents and heat dissipation structures, such as graphite flakes, thermally conductive liquids, air cooling-based and water cooling-based structures, leading to increased weight and large size of the LED lamps, as well as a rise in cost and an increase in difficulty in maintenance.
Therefore, one of the technical problems to be solved for the LED lamps in the prior art is to further increase the heat dissipation effect, with low manufacture cost, light weight and reduced size, and increased efficiency.

Summary of the Invention

The technical problem to be solved by the present invention is to provide a LED lamp that has excellent heat dissipation capacity and can achieve high power output, and that has the advantages of low manufacture cost, light weight and reduced size, and fulfilment of safety requirements.
In addition, the LED lamp of the present invention can be a direct replacement for the incandescent lamp, and has a novel heat dissipation system which fully utilizes a light-pervious bulb shell and cover means in combination for the heat dissipation, thereby allowing for an improved thermal efficiency and therefore a higher LED output power.
The LED lamp according to the present invention comprises a light-pervious bulb shell; a lamp cap for connection to a lamp holder; at least one LED substrate arranged inside the bulb shell; a drive circuit connected to the LED substrate and the lamp cap; a plurality of LED chips mounted on the LED substrate in a manner that the plurality of LED chips are located in the vicinity of an inner surface of the light-pervious bulb shell and emit light towards a plurality of different directions.
The LED lamp according to the present invention further comprises a heat sink mechanism arranged inside the bulb shell, comprising in succession a heat sink head on which the LED substrate is mounted, a support post, and a heat sink viewed from the direction of the light pervious bulb shell to the lamp cap.
The distance between the heat sink head and the inner wall of the light-pervious bulb shell is about 5 mm -10 mm.
The heat sink head is of tapered (e.g. conical) configuration which looks like a half-opened umbrella, with a tip portion in the vicinity of the top of the light-pervious bulb shell and a broader portion in the vicinity of the lamp cap.
The heat sink head comprises at least two side surfaces extending obliquely and outwardly in a direction from the top of the light-pervious bulb shell towards the lamp cap.
Each two adjacent side surfaces are spaced apart at a distance of at least 2 mm - 5 mm.
The LED substrate is fixed on the side surface.
The heat sink head, the support post and the heat sink are made of a metallic material. An insulated cover means is provided between the lamp cap and the light-pervious bulb shell to enclose the heat sink.
The heat sink is of a hollow structure, inside which the drive circuit is arranged.
The LED substrate is a flexible printed circuit board or a metal based circuit board, and is adapted to cooperate in shape with the heat sink head.
According to the present invention, a plurality of LED packaged chips are mounted in a manner that they are located in the vicinity of the inner surface of the light-pervious bulb shell and emit light towards a plurality of different directions, allowing the heat generated by LED packaged chips to dissipate through the nearby light-pervious bulb shell via heat radiation directly to the outside of the bulb shell. By providing the unique design of the heat sink head, the heat dissipation area of the heat sink head with respect to air is increased, and correspondingly the heat dissipation area used for the LED packaged chips is increased; on the other hand, the design of the heat sink head facilitates the flow of hot air inside the bulb shell. According to the invention, the heat is dissipated by heat conduction along a path created by the heat sink head - the support post - the heat sink and by direct heat radiation to the bulb shell, therefore a substantial amount of heat is dissipated via these two thermal pathways, with the achieved effects of improved thermal dissipation efficiency to allow increased output power of the LED lamp.
Compared with the prior art LED lamps, the LED lamp of the present invention can effectively increase heat dissipation efficiency and, accordingly, can provide a higher LED output power, and also has the advantages of small size, light weight, safety and low production cost.

Brief Description of the Drawings

Figure 1 is a schematic view of the structure of the LED lamp according to the present invention;
Figure 2 is an exploded perspective view of the LED lamp according to the present invention.

Detailed Description of the Invention

The present invention is described below in details with reference made to the drawings.
Figure 1 is a schematic view of a LED lamp constructed according to a preferred embodiment of the present invention; Figure 2 is an exploded perspective view of the LED lamp.
As shown in Figure 1, the LED lamp according to the present invention comprises a light-pervious bulb shell 1 made of a transparent material; a lamp cap 7 connected to a lamp holder for provision of electricity to the LED lamp; at least one LED substrate 2 arranged inside the light-pervious bulb shell 1 as a light source of the LED lamp; and a drive circuit connected to the LED substrate and the lamp cap for performing drive control of the LED substrate. A plurality of LED packaged chips are mounted on the LED substrate 2 to form a plurality of LED strings in series connection or in parallel connection, which LED strings are driven by the drive circuit to illuminate. The plurality of LED packaged chips are mounted in a manner that they are located in the vicinity of an inner surface of the light-pervious bulb shell 1 to emit light in a plurality of different directions. Since the plurality of LED packaged chips, where heat is generated, are located in the vicinity of the inner surface of the light-pervious bulb shell 1, the heat generated by the LED chips in use can be quickly transferred through the light-pervious bulb shell 1, which is close to the LED chips, to the outside of the bulb shell.
A heat sink mechanism is further arranged inside the LED bulb shell, comprising a heat sink head 3, a support post 4 and a heat sink 9 viewed from the direction of the light pervious bulb shell 1 to the lamp cap 7. The LED substrate 2 is mounted on the heat sink head 3.
To further increase the heat dissipation efficiency, the heat sink head 3 is of conical configuration which looks like a half-opened umbrella, with a tip portion in the vicinity of the top of the light-pervious bulb shell 1 and a broader portion close to the lamp cap 7. The heat sink head comprises at least two side surfaces extending obliquely, downwardly and outwardly from the tip portion towards the broader portion and then running parallel to the support post made of a metallic material down to the end of the heat sink head. Preferably, the heat sink head is shaped to be in proportion to the light-pervious bulb shell so that the distance between the heat sink head and the inner wall of the light-pervious bulb shell can basically be kept constant. More preferably, the distance between the heat sink head and the inner wall of the light-pervious bulb shell, i.e. the distance between the point of the heat sink head closest to the bulb shell and the inner wall of the bulb shell, is at least approximately 5 mm -10 mm. This arrangement enables quick transfer of the heat generated by the LED chips on the LED substrate fixed on the heat sink 3 to the outside of the bulb shell in a shorter distance. If this distance is too short, restriction on air convection takes place; if this distance is too long, the heat dissipation capacity is adversely affected.
The tip portion of the heat sink head 3 is mechanically (for example by screws, rivets, etc.) secured to the metallic support post 4 with a thermally conductive grease arranged tightly therebetween, and is in thermal connection to the head sink 9 at the rear end thereof.
As shown in Figure 1, the heat sink head 3 in this embodiment comprises four side surfaces extending obliquely, downwardly and outwardly in four different directions from the apex of the head in a direction of the top of the light-pervious bulb shell 1 towards the lamp cap 7, and then running parallel to the metallic support post down to the end of the heat sink head. Preferably, each two adjacent side surfaces are spaced apart at a distance of at least 2 mm - 5 mm, and each two side surfaces are spaced apart at their free ends at a distance of at least 2 mm - 5 mm. Though only four side surfaces are shown in the figures, it can be understood that it is possible to configure a reduced or increased number of side surfaces if necessary. This design of the heat sink head not only increases the heat dissipation area for air, but also facilitates the flow of hot air, enabling convection of a substantial portion of heat generated by the LED packaged chips arranged on the heat sink head to the surface of the bulb shell where the heat is dissipated, even if the LED lamp is in operation horizontally or with the lamp cap arranged to face up or down. Since the side surfaces are spaced apart from one another, the air convection occurs between the LED packaged chips mounted on the respective side surfaces. Through the air convection to the surface of the light-pervious bulb shell, a substantial portion of the generated heat is dissipated therefrom even if the bulb shell is placed horizontally or with the lamp cap facing down. This ensures a better heat dissipation effect.
Preferably, the LED substrate is mounted on the respective side surface such that the heat sink head is provided with the LED substrate facing outward. Therefore, the LED chips can be mounted on the heat sink head through the LED substrate to emit light in at least two directions. It is obvious that the increase in the number of side surfaces of the heat sink head and the number of the LED chips may result in the larger coverage of illumination in different directions. In addition, the LED packaged chips can also be mounted on the conical apex of the heat sink head to provide the illumination coverage in the tapering direction of the tip portion, thereby achieving the requirement for illumination coverage in all directions.
As shown in Figure 2, the heat sink head 3, the support post 5 and the heat sink 9 forming the heat sink mechanism are all made of materials having good thermal conductivity, preferably metallic materials, such as aluminium or aluminium alloys. The heat sink 9 is hollow, in which the drive circuit 8 is arranged to rectify the power supply mains to a safety voltage required for the LED chips. An insulated cover means is arranged between the lamp cap and the light-pervious bulb shell to enclose the heat sink. The cover means is made of a material that is electrically insulating while having good thermal conductivity in order to fulfil safety and heat dissipation requirements.
Further, at the end of the support post 4 that is close to the heat sink 9, a fixing portion 5 for fixing the heat sink 9 is arranged. The fixing portion 5 can be made of a material of high thermal conductivity such as a metallic material, and has a hollow portion tightly engageable with the heat sink 9, and the drive circuit 8 is arranged inside a space created after the engagement of the heat sink 9 with the fixing portion 5. Such an arrangement can further enhance the heat dissipation of the LED packaged chips 2 on the heat sink head 3, with a result that the LED lamp operates with a higher output power.
The LED substrate is a flexible printed circuit board or a metal based circuit board, and is adapted to match in shape with the heat sink head and is fixed on the side surface of the heat sink head using a thermally conductive material. Thus the heat sink head may be provided in various shapes according to the respective shapes of the bulb shell, and the LED substrate can be easily fixed on the heat sink head.
Since the drive circuit 8 is live, an electrically insulating cover is needed to insulate the drive circuit 8 from the heat sink 9 and other metallic parts. In this regard, the heat sink 9 is completely enclosed by the insulated cover means 6 arranged between the lamp cap 7 and the light-pervious bulb shell 1, and the lamp cap 7 is installed at the tail end of the cover means 6. The lamp cap is adapted for connection to the lamp holder to introduce electric power to the LED lamp.
In the LED lamp according to the invention, the electric connection among the lamp cap 7, the drive circuit 8 and the LED substrate is well-known in the art, and will not be discussed herein.
The light-pervious bulb shell 1 may be transparent, milky, frosted or colored, or may be provided with a diffuse transmitting coating on its outer surface, or provided partially with a reflective coating. The light-pervious bulb shell 1 can be selected from the group consisting of A-type, G-type, R-type, PAR-type, T-type, candle-shaped type and any other type known in the prior art.
The LED packaged chips used in the LED lamp of the present invention is a standard packaged chip having an operating voltage of 3V to 84V (DC) and matchable with the heat sink head and the drive circuit, and can be adapted to operate at various operating voltages and provide the output powers and the forward voltages according to safety regulations for a LED lamp in different regions around the world.
The drive circuit for the LED lamp of the present invention may be selected from an isolated switch circuit, a non-isolated switch circuit, a linear power supply circuit or a resistor-capacitor series circuit.
Since the LED lamp is filled with the air at normal atmospheric pressure and requires no dedicated gas, the cost involved can be kept low.
Embodiments of the invention as described in the paragraphs below.

1. A LED lamp comprising:
- a light-pervious bulb shell,
- a lamp cap for connection to a lamp holder,
- at least one LED substrate arranged inside the light-pervious bulb shell,
- a drive circuit connected to the LED substrate and the lamp cap,
- characterized in that a plurality of LED chips are mounted on the LED substrate in a manner that the LED chips are located in the vicinity of an inner surface of the light-pervious bulb shell and emit light towards a plurality of different directions.
2. The LED lamp according to paragraph 1, further comprising a heat sink mechanism that is arranged inside the bulb shell, wherein the heat sink mechanism comprises in succession a heat sink head on which the LED substrate is mounted, a support post and a heat sink viewed from a direction of the light-pervious bulb shell to the lamp cap.
3. The LED lamp according to paragraph 2, characterized in that the heat sink head is spaced apart from an inner wall of the light-pervious bulb shell at a distance of 5 mm - 10 mm.
4. The LED lamp according to paragraph 3, characterized in that the heat sink head is of tapered configuration which looks like a half-opened umbrella, with a tip portion in the vicinity of a top of the light-pervious bulb shell and a broader portion in the vicinity of the lamp cap.
5. The LED lamp according to paragraph 4, characterized in that the heat sink head comprises at least two side surfaces extending obliquely and outwardly in a direction from the top of the light-pervious bulb shell towards the lamp cap.
6. The LED lamp according to paragraph 5, characterized in that each two adjacent side surfaces are spaced apart at a distance of at least 2 mm - 5 mm.
7. The LED lamp according to paragraph 5, characterized in that the LED substrate is fixed on the respective side surface.
8. The LED lamp according to paragraph 2, characterized in that the heat sink head, the support post and the heat sink are made of a metallic material, and an insulated cover means is provided between the lamp cap and the bulb shell to enclose the heat sink.
9. The LED lamp according to paragraph 8, characterized in that the heat sink is of a hollow structure in which the drive circuit is arranged.
10. The LED lamp according to any of paragraphs 1 to 9, characterized in that the LED substrate is a flexible printed circuit board or a metal based circuit board, and is adapted to cooperate in shape with the heat sink head.

The above embodiments of the present invention are merely provided as preferred embodiments. Various modifications and/or alterations to be made under the principle of the present invention shall all fall into the scope of protection of the present application.

Descriptions of Numbers in Figures

1. Light-pervious bulb shell
2. LED substrate
3. Heat sink head
4. Metallic support post
5. Fixing portion for fixing heat dissipater
6. Cover means
7. Lamp cap
8. Drive circuit
9. Heat sink

Claims

A LED lamp comprising:
a light-pervious bulb shell (1),

a lamp cap (7) for connection to a lamp holder,

at least one LED substrate (2) arranged inside the light-pervious bulb shell (1),

a drive circuit (8) connected to the LED substrate (2) and the lamp cap (7),

characterized in that a plurality of LED chips are mounted on the LED substrate (2) in a manner that the LED chips are located in the vicinity of an inner surface of the light-pervious bulb shell (1) and emit light towards a plurality of different directions, and

the LED lamp further comprises a heat sink mechanism that is arranged inside the bulb shell, wherein the heat sink mechanism comprises in succession a heat sink head (3) on which the LED substrate is mounted, a support post (4) and a heat sink (9) viewed from a direction of the light-pervious bulb shell (1) to the lamp cap (7), and wherein the heat sink head (3) is of tapered configuration which looks like a half-opened umbrella, with a tip portion in the vicinity of a top of the light-pervious bulb shell (1) and a broader portion in the vicinity of the lamp cap (7).
The LED lamp according to claim 1, characterized in that the heat sink head (3) is spaced apart from an inner wall of the light-pervious bulb shell (1) at a distance of 5 mm -10 mm.
The LED lamp according to claim 1, characterized in that the heat sink head (3) comprises at least two side surfaces extending obliquely and outwardly in a direction from the top of the light-pervious bulb shell (1) towards the lamp cap (7).
The LED lamp according to claim 3, characterized in that each two adjacent side surfaces are spaced apart at a distance of at least 2 mm - 5 mm.
The LED lamp according to claim 3, characterized in that the LED substrate (2) is fixed on the respective side surface.
The LED lamp according to claim 1, characterized in that the heat sink head (3), the support post (4) and the heat sink (9) are made of a metallic material, and an insulated cover means (6) is provided between the lamp cap and the bulb shell to enclose the heat sink (9).
The LED lamp according to claim 6, characterized in that the heat sink (9) is of a hollow structure in which the drive circuit (8) is arranged.
The LED lamp according to any of claims 1 to 7, characterized in that the LED substrate is a flexible printed circuit board or a metal based circuit board, and is adapted to cooperate in shape with the heat sink head (3).