24.06.10

Fraunhofer paves way for paper-thin TVs

The Fraunhofer Institute for Production Technology (IPT) says it can slash the cost of large scale LED optics, paving the way for cost-effective and efficient manufacture of super-slim displays. Largely thanks to LED backlighting, displays are constantly slimming down but manufacturing techniques are still complex and expensive. Now, IPT says it has developed a machine that can easily produce large-scale fibre optic film that will remove many of the headaches associated with LED.

IPT argues that LED technology is disadvantaged by the fact it is a point light source and displays are two-dimensional. It creates a massive challenge when trying to distribute the light from an LED evenly on a large surface, without massive energy loss.

However, IPT in Aachen, says it is in the process of creating a “one-of-a-kind machine”. This will allow researchers to produce fibre optic film that solves this problem and distributes the light two-dimensionally. The films possess superficial structures measuring in the single-digit micrometer range, while the sheets themselves measure at two by one metre in size. IPT claims the sheets are the largest of their kind throughout the EU and that they can be produced cost-effectively and with energy-efficiency in mass reproduction.

To do so, the researchers of IPT developed a process chain with which they can populate large-scale sheets with the necessary microstructures. “It‘s an ultraprecise process,” explained Dr. Christian Wenzel, senior engineer at IPT.

Using pinpoint accuracy, the machine must apply the smallest structures – just a few micrometers in size – onto the surface of the film in a periodic sequence. “In order to produce the stamp, we use special diamond tools,” adds Wenzel.

The stamp consists of a gossamer-thin nickel sheet, and itself is also infinitesimal. Its surface equals at most two by two millimetres. Like a dot matrix printer, it must then process a sheet measuring two by one metre in size, guided by the ultraprecision machine. “Within a few days, we completely structured the entire surface. With the previous approach, the process would have taken weeks, or even months,” said Wenzel. The preliminary product is a transparent and optically conductive plastic panel.

In order to determine if the microstructured master possesses the desired characteristics, it must first be tested based on a few parameters. “The machine can accomplish this task as well,” said Wenzel. If approximately 80 per cent of the surface is completely structured, the machine tests the properties of the sheet. If these properties are not consistent with the optical design settings, then the machine can implement the necessary corrections during the imprint process. “Well, we are optimising the component while it‘s still in the machine,” Wenzel explained. Once the plastic surface has the desired light control capabilities, then the engineers immerse the master into a nickel bath and galvanise it. The nickel shim created in this manner can then go into mass replication.

“With our ultraprecise machine, we are capable of producing an entire array of systems with background lighting,” said Wenzel.

IPT sees applications in displays, architectural lighting and car interior lighting.