How Does Graphene Change LED Filament Lamp

- Jul 18, 2019-

In recent years, the fiery degree of the filament lamp in the LED industry can be said to be bursting. From the current situation of the heat of Jiangsu and Zhejiang, it has gradually turned into a national and even global LED filament heat. Graphene is not only in the LED industry, but also in all material fields. For this, Ma Jingbo, vice president of Shandong Jingtaixing, presented his views on two “hot” collections.


1. Is LED ready to replace incandescent lamps?


Talking about the filament lamp must first talk about incandescent lamps. At present, the roadmap for eliminating incandescent lamps has been released all over the world. China has clearly banned the production and sales of incandescent lamps above 60 watts. Other Western countries (USA, Canada, Australia) have clearly withdrawn from incandescent lamps. So is the LED replacement incandescent really ready?


Dr. Ma Wenbo raised the following six questions:


The efficacy specifications of incandescent lamps are completely replaced from 25 watts to 100 watts. Is the LED ready in the same volume?


The illuminating effect of the incandescent lamp in all directions, the luminous curve of the full light distribution, can the current LED products be completely realized?


Third, is the LED's eye-catching visual sensory effect LED really realized?


Fourth, is the incandescent lamp low cost price LED realized?


Fifth, can incandescent ultra-light weight LEDs be realized?


Sixth, can incandescent lamps be close to 100% of color rendering index LED lighting products?


2. Why do you want to do it?


Don't forget your heart and return to the product. From the development of the whole light source, incandescent lamp is the perfect product, because it has nearly 100 indicators, and it is environmentally friendly, has no toxic and harmful pollutants, and is also very light, low cost, and the visual effect is accepted by most people. Although the energy-saving lamps have a large light-emitting angle, the light effect is stronger than that of incandescent lamps, but it contains mercury, so the development was quickly replaced by LEDs.


As the LEDs begin to enter people's sights, they quickly become popular with the concept of energy saving. At present, the market sees basically 80-90LM/W, which is 8 to 10 times higher than incandescent lamps, and also has a relatively large illumination angle, but its illumination angle is still inferior to incandescent lamps, which is the appearance of LED filament lamps. s reason.


The filament lamp started in 2012, when there were already products in Hong Kong's specialty stores. In 2013, many manufacturers began to pursue it and matured to this day. Therefore, this product can see its key technical features, not only has a large illumination angle, is lighter than traditional LED light, and is environmentally friendly and lighter in weight.


3. How does graphene change the filament lamp?


Since the structure of the LED filament lamp has no redundant heat dissipation structure, it can only rely on gas and heat dissipation of the casing. According to the three-element conduction, convection and radiation of heat transfer, the current filament lamp has no conduction, only convection and radiation. However, it is mainly convective heat dissipation, and the proportion of radiation is small. If the technology of graphene is introduced into the filament lamp, it is intended to use the heat radiation characteristics of graphene to increase the heat dissipation of the filament lamp to extend the service life of the filament lamp.


Based on this idea, by testing the graphene on the same copper sheet and not coating it, the black body radiation performance is tested. It can be clearly seen that the graphene is coated, its heat radiation characteristics are very obvious, but no graphite is applied. Aene has no obvious thermal radiation properties. In addition, the graphene-coated material was coated on copper foil or aluminum foil. Comparative thermal imaging experiments were also carried out, and the results were consistent, so graphene has better heat radiation characteristics.


Based on the results obtained by the experiment, graphene is used on the metal substrate at the back position of the filament, and the heat generated by the LED heating radiates heat through the graphene, and the heat conduction gas in the bulb is used to achieve effective convection and lower the temperature.


According to the comparison between the graphene coated and uncoated graphene products, it can be seen that the junction temperature of the graphene-coated chip is 3-5 degrees lower than the junction temperature of the uncoated graphene, so that the junction temperature of the chip can be significantly reduced. Thus, the life of the filament can be extended.


4, the development trend of filament lamps


Ma Wenbo's development trend on filaments mentioned Jing Taixing's two directions of layout. One is the direction of flexible development and the other is the direction of intelligence.


At present, some flexible products have appeared in the LED industry, but mainly straight filaments or curved filaments. Ma Wenbo said that it is more important for Jingtaixing to make the flexible filament lamp reach the main lighting product. Jingtaixing is ready to consider combining graphene and materials to achieve the light specifications required by the main lighting.


Regarding the development direction of the filament, the intelligent LED filament lamp, Ma Wenbo said that because there are more string changes in the filament lamp, there are more than 20 chips in one filament, and the VF value of each chip is different. Differences in VF values result in uneven current distribution, and unevenness can cause current overload in a certain filament, which can cause a sharp drop in the life of the filament. Jingtaixing encapsulates the smart device inside the filament. The chip has good current limiting characteristics to ensure that the filament current is 10-12mA, so the reliability will be greatly extended.


The ultimate goal is to really remove the power supply through the application of these devices. Because the current filament lamp also contains a power supply in the lamp cap, and the future filament lamp does not require a power source, the illumination of the incandescent lamp is achieved only by the current limiting characteristics of the devices at both ends of the filament.