CN106287339B

CN106287339B - LED filament

Info

Publication number: CN106287339B
Application number: CN201510316656.9A
Authority: CN
Inventors: 江涛; 徐宏; 江文章
Original assignee: Jiaxing Super Lighting Electric Appliance Co Ltd
Current assignee: Jiaxing Super Lighting Electric Appliance Co Ltd
Priority date: 2015-06-10
Filing date: 2015-06-10
Publication date: 2020-10-02
Anticipated expiration: 2035-06-10
Also published as: CN106287339A

Abstract

The invention provides an LED filament, which comprises: a transparent support; the metal electrodes are respectively arranged at two opposite ends of the transparent bracket; the middle of the metal electrode is provided with a hole, and the transparent bracket passes through the hole; the LED chips are arranged in the transparent bracket and form electrical connection in a gold wire routing mode or a crystal covered structure mode; the silica gel wraps the LED chip; the LED chip is an alternating current type light emitting diode or a high voltage type light emitting diode. The invention has better heat dissipation effect and luminous efficiency.

Description

LED filament

Technical Field

The invention relates to the field of illumination, in particular to an LED filament.

Background

The LED has the advantages of environmental protection, energy conservation, high efficiency and long service life, so the LED generally receives attention in recent years and gradually replaces the status of the traditional lighting lamp. However, the light emitted by the LED has directivity, unlike the conventional lamp that can illuminate in a wide-angle range, so how to design an LED lamp that achieves ultra-large wide-angle and full-ambient illumination is an object of research and development in the LED industry.

In recent years, an LED filament capable of making an LED light source emit light similar to a traditional tungsten filament bulb lamp and achieving 360-degree full-angle illumination is increasingly emphasized in the industry. The LED filament is manufactured by connecting a plurality of LED chips in series and fixing the LED chips on a narrow and long glass substrate, wrapping the whole glass substrate with silica gel doped with fluorescent powder, and then electrically connecting. However, the glass substrate has poor heat conduction and is easily broken by vibration, which causes the LED chip to be failed due to disconnection in series. Therefore, a metal substrate which is not easy to break is replaced by a metal substrate, but the metal substrate cannot transmit light and has the defect of light shielding, so that the luminous efficiency of the LED filament is low, and therefore how to simultaneously strengthen the toughness of the LED filament substrate and simultaneously consider the heat conduction characteristic and the luminous efficiency of the LED filament is a common effort target in the LED lighting industry.

Disclosure of Invention

It is therefore an object of the present invention to overcome the above-mentioned drawbacks of the prior art and to provide an LED filament.

The invention provides an LED filament, which comprises:

the transparent bracket can be a bottomless frame; when the transparent support is not provided with the bottom, the support can not shield light, so that the luminous efficiency of the filament can be improved;

the metal electrodes are respectively arranged at two opposite ends of the transparent bracket; the middle of the metal electrode is provided with a hole, and the transparent bracket passes through the hole; the material can be condensed through the holes during the manufacturing process of the bracket, so that the stability of the metal electrode is favorably improved;

the LED chips are arranged in the transparent bracket and form electrical connection in a gold wire routing mode or a crystal covered structure mode; when the LED chips in the filament are connected by gold wires, the gold wires have excellent ductility, the stress extruded by the LED chips can be released timely, and the problem of electrical connection disconnection is not easy to occur; when the flip chip structure is adopted, the defect of inconvenience of wire bonding can be improved.

And the silica gel wraps the LED chip without filling the inside of the whole transparent support.

The LED chip is an alternating current type light emitting diode or a high voltage type light emitting diode. The cost of the rectifying and voltage reducing electronics can be reduced.

Furthermore, fluorescent powder is doped in the silica gel, and the transparent support is made of a light-transmitting material. When the fluorescent powder is doped into the silica gel, the silica gel has certain softness and refractive index, and is suitable for protecting the LED chip and improving the light-emitting rate of the LED chip; in addition, high-temperature-resistant transparent silica gel with higher hardness or other plastics with the same property and difficult deformation can be selected to replace the original silica gel, or other substances are doped in the original silica gel to enhance the hardness of the silica gel, and the silica gel has enough hardness to support and protect the LED chip, so that the LED filament without the support can be formed without using any support to support the LED chip, and the problem that the support shields light or the traditional glass substrate is easy to break is solved.

Furthermore, a metal conducting circuit is arranged on the transparent support and used for electrically connecting the LED chips.

Further, the silica gel forms a lens on the outer layer of the LED chip. The light emitting angle is adjusted, and the space is left to enable the LED chip to radiate heat more easily.

Further, the metal electrode is covered with the silica gel.

Furthermore, a plurality of small brackets which are correspondingly protruded up and down are arranged in the transparent bracket and can be used for supporting the LED chip.

Furthermore, part of the LED chips are electrically connected in series to form at least two units, and the units are electrically connected in parallel.

Furthermore, a metal conducting circuit is arranged on the small support. For the LED chip to be electrically connected

Furthermore, the LED chip is a strip-shaped chip, and the strip-shaped chip has the problem of uniform current diffusion distribution; the surface of the LED chip is plated with indium tin oxide, so that the current uniform diffusion distribution and the luminous efficiency of the chip are improved.

Further, the LED chips are electrically connected in series or in parallel.

Compared with the prior art, the beneficial results of the invention are that the invention comprises any one or any combination of the following effects:

1) compared with the traditional substrate, the transparent support without the bottom is adopted, and the light emitting efficiency of the filament is improved because the light rays are not shielded;

2) the LED filament supports the LED chip by the silica gel with improved hardness without an additional support, so that the LED filament has better heat dissipation effect and luminous efficiency;

3) in the manufacturing process of the transparent bracket, the material can pass through the holes of the metal electrode and then be condensed, so that the stability of the metal electrode can be effectively improved;

4) silica gel forms a lens on the outer layer of the LED chip to adjust the light-emitting angle;

5) the problem of uniform distribution of current diffusion is solved by adopting a strip chip; indium tin oxide is plated on the surface of the LED chip, so that the current uniform diffusion distribution and the luminous efficiency of the chip are improved;

drawings

FIG. 1 is a diagram of a filament structure of an LED with LED chips connected in series according to a first embodiment of the present invention;

FIG. 2 is a diagram of a LED filament structure with parallel LED chips according to a first embodiment of the present invention;

FIG. 3 is a diagram of an LED filament with LED chips connected in series according to a second embodiment of the present invention;

FIG. 4 shows a partial enlarged structural view of FIG. 3;

FIG. 5 is a diagram of a LED filament structure with parallel LED chips according to a second embodiment of the present invention;

FIG. 6 shows a partial enlarged structural view of FIG. 5;

FIG. 7 is a structural diagram of a third embodiment of the LED filament of the present invention;

FIG. 8 is a partial enlarged structural view of an LED filament according to a third embodiment of the present invention;

Detailed Description

FIG. 1 shows an embodiment of the present invention, in which an LED filament 1 includes a transparent frame 2, metal electrodes 3 disposed at two ends of the transparent frame 2, an LED chip 4 and gold wires 5 disposed in the transparent frame 2, and a silica gel 6 disposed inside the transparent frame 2 and wrapping the LED chip 4 and the gold wires 5, the transparent frame 2 is a bottomless frame with a size of about 40 × 2.4.4 mm²The thickness is 0.6mm, the material is high temperature resistant light-transmitting material, high temperature resistant transparent silica gel or other plastics with the same property can be selected, because the transparent support 2 has no bottom, the doubtful possibility of shielding light can not be generated, the luminous efficiency of the filament can be improved, metal parts are embedded at two ends of the transparent support 2 to be used as metal electrodes 3 of the filament, and the size of the metal parts is about 3 × 1mm²The thickness is 0.4mm, holes can be arranged in the middle of the support, and the support is made ofDuring operation the material can re-condense through these holes, thus contributing well to the robustness of the metal electrode 3. The metal electrode may have a hole (not shown) at the outer end of the support for electrical connection of the LED filament 1 during assembly of the bulb lamp. The bracket may also have a metal conductive trace thereon to facilitate electrical connection of the LED chip 4 subsequently disposed in the middle of the bracket.

The LED chips 4 can be placed on a carrier in advance, a plurality of LED chips 4 are connected in series by gold wire bonding to form an LED lamp string, then the LED lamp string is moved to the middle of the transparent support 2, the head and the tail of the LED lamp string are electrically connected with the metal electrodes 3 at the two ends of the transparent support 2 by the gold wire bonding, then the high-heat-conductivity silica gel 6 doped with fluorescent powder is coated on the middle of the transparent support 2 from the upper part of the transparent support 2 to cover all the LED chips 4 and the metal electrodes 3 in the transparent support 2, then the carrier under the LED chips 4 is removed, the high-heat-conductivity silica gel 6 doped with fluorescent powder is continuously injected into the middle of the transparent support 2 from the back of the transparent support 2 to completely wrap the LED chips 4, and the LED lamp filaments of the transparent support are manufactured after the silica gel 6 is cooled and condensed.

Fig. 3-6 show another embodiment of the present invention, which is a slight modification of the above-mentioned manufacturing method, after the LED string and the metal electrodes 3 at the two ends of the transparent support 2 are electrically connected by gold wire bonding, the carrier under the LED chip 4 can be removed first, then the LED string and the transparent support 2 are placed into a mold together, and the transparent support 2 is filled with the silica gel 6 doped with the fluorescent powder by molding (molding) to completely wrap the LED string, so as to complete the manufacturing of the LED filament of the transparent support. However, when the silicone rubber 6 is injected into the transparent support 2, it is not necessary to fill all the space inside the whole transparent support 2, as long as it can properly wrap all the LED chips 4, for example, as shown in fig. 3-6, by the design of the molding die or the change of the silicone rubber coating method, the injected silicone rubber 6 does not fill the inside of the transparent support 2, but only completely wraps the LED chips 4, even a lens can be formed on the outer layer of the chip to adjust the light emitting angle, and the empty space allows the LED light string to dissipate heat more easily. Because the LED chips 4 in the filament are connected by the gold wires 5, and the gold wires 5 have excellent ductility, the stress extruded by the chips in the LED lamp string can be released timely, and the problem of electrical connection disconnection is not easy to occur.

The LED strings are electrically connected in series, however, the connection mode between the LED chips 4 is not limited to this mode, and the electrical connection of the chips can also be accomplished by metal conductive traces (not shown) laid on the transparent support 2. For example, in fig. 2, the positive electrodes of all the LED chips 4 can be connected to the metal conductive traces of the upper frame by gold wires 5, and then connected to the metal electrode 3 at one end of the frame by the metal conductive traces. Similarly, the negative electrodes of all the LED chips 4 are connected to the metal conductive circuit of the bracket below by gold wires 5, and then connected to the metal electrode 3 at the other end of the bracket by the metal conductive circuit, so that the LED lamp string is formed by combining in an electrical parallel mode. However, the electrical connection of the chips of the LED light string is not limited to these two modes, and a plurality of chips may be connected in series to form a small unit, and then the small units are connected to the metal conductive circuit of the bracket by gold wires to form a parallel electrical connection combination.

Further, the high thermal conductivity silica gel 6 used for doping the phosphor to coat the LED chip 4 in the embodiment has a certain softness and a certain refractive index, and is suitable for protecting the LED chip 4 and increasing the light extraction rate thereof. In addition, high-temperature resistant transparent silica gel with higher hardness or other plastics with the same property and difficult deformation can be selected to replace the original silica gel, or other substances are mixed in the original silica gel 6 to enhance the hardness of the silica gel. When the silicone rubber 6 completely wraps the whole LED light string and the metal electrodes 3 at the two ends in a molding manner, the silicone rubber has enough hardness to support and protect the whole LED light string, so that the LED filament without a support can be formed without using any support to support the LED light string, and the problem that the support shields light or the traditional glass substrate is easy to break is solved.

Fig. 7-8 show another embodiment of the present invention, in which the filament transparent support 2 is also a bottomless frame, and is made of a high temperature-resistant transparent material, such as high temperature-resistant transparent silicone or other plastics with the same properties. As shown in the figure, the difference from the previous embodiment is that a plurality of small brackets 21 protruding up and down correspondingly are arranged in the bracket, and the function of the small brackets is mainly to support the LED chip 4. Because the transparent support 2 has no bottom, the doubtful light shielding is avoided, and the luminous efficiency of the filament can be improved. As described in the previous embodiment, metal members are embedded at two ends of the transparent support 2 to serve as the metal electrodes 3 of the filament, the size of the metal members is as described above, and some holes can be preset in the metal members, so that materials can penetrate through the holes to be condensed in the support manufacturing process, thereby being good for the stability of the metal electrodes 3. The support and the small protruded support 21 can also be provided with metal conductive circuits to help the LED chip 4 placed in the middle of the support to be electrically connected. Since the small support 21 may also be distributed with metal conductive traces, the LED chip 4 of this embodiment may be electrically connected in a flip-chip structure in addition to the gold wire bonding manner, so as to eliminate the inconvenience of gold wire bonding. The coating mode of the silica gel 6 can also only coat the periphery of the single LED chip 4, the whole transparent bracket 2 is not required to be filled, the LED chip 4 is only completely wrapped, even a lens is formed on the outer layer of the chip to adjust the light-emitting angle, and the space is left to enable the LED to be more easily radiated.

Referring to another embodiment of the present invention, after all chip processes are completed, the conventional LED must be cut into individual LED chips. In this embodiment, however, the LED epitaxial wafer is preferably cut into the LED light bar 11 in only one horizontal direction to fabricate the LED filament,

the substrate sapphire substrate of the epitaxial wafer can be used for replacing a glass substrate which is commonly used in the market, an LED chip does not need to be adhered to other substrates or a bracket, and the heat conductivity coefficient of the sapphire substrate is as high as 120W/mK and is far better than 1W/mK of the traditional glass. The LED chips 4 on the LED light strip 11 can be electrically connected by bonding gold wires 5 by a packaging process, or can be connected by plating metal wires on the LED chips 4 by a semiconductor process. The specification of the LED chip 4 is preferably a long chip, and the long chip is less likely to have the problem of uniform current spreading, for example, the LED chip 4 with the specification of 10 × 20 is suitable, and for manufacturing a filament with a 40mm long LED light bar, 18 LED chips should be placed on the filament after the distance between the LED chips 4 is reduced. In addition, a layer of conductive transparent Indium Tin Oxide (ITO) is plated on the surface of the LED chip 4, so that the current uniform diffusion distribution and the light emitting efficiency of the chip can be improved.

The manufactured LED light bar 11 can be adhered with metal electrodes 3 at the bottoms of the two ends thereof by using high thermal conductive adhesive or solder paste, and then gold wires 5 are bonded between the LED chips 4 and the metal electrodes 3 at the two ends of the LED light bar 11 for electrical connection by using a packaging and wire bonding process, and the metal electrodes 3 at the two ends of the LED light bar 11 can be adhered in a flip-chip package manner. And finally, placing the LED light bar 11 carrying the metal electrode 3 into a mold, and wrapping the periphery of the LED light bar with silica gel 6 doped with fluorescent powder in a molding manner to complete the manufacture of the LED filament. The size of the metal electrode 3 is as described above, and some holes can be preset in the middle of the metal electrode, through which the silicone gel can re-condense during the molding process, so as to provide a good help for the stability of the metal electrode 3.

In all embodiments of the present invention, the specification of the adopted LED chip 4 is preferably a long chip, and the long chip has less problem of uniform current spreading and meets the structural shape requirement of the LED filament. However, the scope of the LED chip can be used without limitation, and for example, an alternating current light emitting diode (AC LED) and a high voltage light emitting diode (HV LED) are also excellent choices for manufacturing the LED filament. Because the LED lighting apparatus must use the commercial power, and the power supply provided in the market is a high-voltage ac power supply, it is not suitable for being directly used in the LED light source, and electronic components for rectification and voltage reduction must be additionally added to the LED lighting apparatus. Because the LEDs are diode components, and the proper combination has the efficacy of rectification, and the series connection of a plurality of LEDs, i.e. the series connection of a plurality of resistors, can bear high-voltage current, the alternating current type light emitting diode (AC LED) and the high-voltage type light emitting diode (HV LED) are also very suitable for manufacturing LED filaments, and the cost of rectification and voltage reduction electronic devices can be reduced.

As mentioned above, the present invention fully complies with the three requirements of the patent: novelty, creativity and industrial applicability. While the invention has been described in terms of preferred embodiments, it will be understood by those skilled in the art that the examples are intended in a descriptive sense only and not for purposes of limitation. It should be noted that equivalent variations and substitutions to those of the embodiments are intended to be included within the scope of the present invention. Therefore, the protection scope of the present invention is subject to the scope defined by the appended claims.

Claims

1. An LED filament, comprising:

the transparent bracket is a bottomless frame;

the metal electrodes are respectively arranged at two opposite ends of the transparent bracket; the middle of the metal electrode is provided with a hole, and the transparent bracket passes through the hole;

the LED chips are arranged in the transparent bracket space, and the LED chips, the LED chips and the metal electrodes form electrical connection in a flip chip structure mode; and

the LED lamp comprises a transparent support, a silica gel, a plurality of LED chips and a plurality of LED chips, wherein each LED chip is completely wrapped by the silica gel, fluorescent powder is doped in the silica gel, the transparent support is made of a light-transmitting material, a gap is formed between the silica gel and the transparent support, a lens is formed on the outer layer of each LED chip by the silica gel, and a plurality of small supports which are correspondingly protruded up and down are arranged in a space formed by the transparent support;

the LED chip is an alternating current type light emitting diode or a high voltage type light emitting diode.

2. The LED filament of claim 1, wherein the transparent support has metal conductive traces thereon.

3. The LED filament of claim 1, wherein the silicone gel covers a portion of the metal electrode.

4. The LED filament of claim 1, wherein a portion of said LED chips are electrically connected in series to form at least two units, said units being electrically connected in parallel.

5. The LED filament of claim 1, wherein the small support has metal conductive traces thereon.

6. The LED filament according to claim 3 or 4, wherein the LED chip is an elongated chip, and the surface of the LED chip is plated with indium tin oxide.

7. The LED filament of claim 5, wherein the LED chips are electrically connected in series or in parallel.