27 March 2019
A new generation of flexible LED-based technology is opening a whole new world of flat, flexible, low energy lighting.
LED stands for Light Emitting Diode: a tiny chip is coated with an electroluminescent material that glows when an electric charge passes through it. The early ones were made from heavy metals such as gallium and encapsulated in a protective glass vial or bulb with two metal pins for the power supply. But the bulbs were not very bright on their own and wiring them up in a line is messy and time-consuming
So manufacturers started to print long lines of chips on a flexible backing - the tapes you will be familiar with. These deliver a continuous line or band of light- but give a ‘spotty’ look. The tapes also tend to heat up because they have to carry a lot of power to drive the chips at the end of the line. Aluminium channels and plastic diffusers were designed to sort this out - but it is always a compromise between evening out the dots and reducing the brightness of the light.
This new generation of LED’s gets around this by using thin films of electroluminscent material to make a continuous line of light- no more individual chips of points of light - the flexible neon 'rope' was born.
Manufacturers looking for cheaper luminescent materials learnt how to get organic hydrocarbon chains to glow - and started to use them instead of the metals: the Organic LED - or OLED.
An LED panel or strip is typically built from four layers – substrate, or structural framework, cathode and anode layers (‘positive’ and ‘negative’ charged layers which produce a flow of electrons) and an organic layer or ‘mesh’ between the two. The electrons pop in and out of these ‘holes’, shedding energy as they go – producing light in the process. Tinted plastic layers are added to the substrate to create colours
Products like kindles or calculator displays or the flexible bands used in a growing number of lights change the image or pattern relatively slowly. These are built using a ‘passive matrix OLED’ – or PMOD. The device or driver sends a signal to power up specific areas of the film to create the image we see. Power is left on until the driver sends a new instruction to switch the power off.Smart phones or HD televisions where a high refresh rate and fine detail is needed use an active matrix (AMOLED). A thin film of transistors supplies power to each of the pixels individually to give a remarkable degree of control and quick response.
These products tend to ‘glow’ like a lightbox rather than ‘shine’ like a spotlight – but this is also likely to change as this technology evolves
Here are two UK suppliers and a couple of websites for more information.
I’d be delighted to talk you through the options – do get in touchfor a free conversation.
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