TECHNOLOGY DEVELOPMENT
In previous years, lamps based on field emission technology were developed with the aim of showing that the technology and concept worked and have the ability to fulfil the technological requirements for performance. Before and during 2011 the essential work started on meeting requirements for costs and manufacturability for fast industrialisation. This also means that certain parts of the technology must be changed. The focus shifted towards being able to fulfil performance requirements in a uniform, reproducible and repeatable way and with materials that are simple, cheap and controllable. For example, a new cathode material has been introduced (zinc oxide, ZnO) and new shapes have been introduced for lamp prototypes (T8 tubes, flat lamps). The entire work is being done with a basic understanding of how individual details work together and how they affect each other and the properties of the entire lamp. Some of the progress made during 2011 is briefly described below.
Drive electronics
The first cost-optimised drive electronics prototype was developed during 2011. The unit is compact, 30 times smaller than previous drive electronics. At high volumes, the cost will be able to meet the requirements now being forecast by LightLab. The aim for 2012 is to further develop the unit for integration and to be able to fit the drive electronics in a socket for a bulb. The unit must have a high degree of efficiency and the initial goal of 85% has already been achieved, which is better than most existing drives for LED and fluorescent tubes.
Cathode technology
The carbon foam based cathode has been successfully developed to show that the concept and technology work, but was deemed to be too costly and complicated to manufacture in high volume. During the year, we have made great progress with the new zinc oxide (ZnO) based cathode, which is being constantly optimised. The material is a semiconductor; it is cheap and has very high stability, both chemically and thermally. Nanostructures in ZnO can be controlled in shape and geometry, which gives a degree of freedom and new opportunities. LightLab is using and developing a wet chemical method of creating ZnO cathodes on a nano scale with controllable and desirable properties. The method occurs at low temperature (<100C), which further contributes to cost-effective manufacture. Ongoing and future work is focused on the sensitivity of the process to temperature, concentration and pH.
Anode technology
Anode development is aimed at efficiency (i.e. how much light is emitted for each electron that strikes it). In order to achieve an even better lifetime, a further developed luminescent powder has been introduced during the year. Theoretically the new luminescent powder gives three times the previous lifetime, which is also indicated by initial measurements taken by a third party. In total, this has resulted in prototype lamps with considerable improvements to expected lifetime and significant production advantages. Measurements are currently being made to verify these properties.
Close contact with manufacturers of luminescent powder are expected to provide further opportunities for optimising both performance and lifetime.
Lamps/prototypes with different shapes
The development of cathodes in T8 ("fluorescent tube") format is aimed at manufacturability and uniformity. The cathode is being constantly optimised. New, copyright protected cathode structures have been developed for flat format lamps and work has begun on adapting these for production. The lamp and the cathode are now being further developed with a view to cost and uniformity.