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Fabutech Uses Titanium Dioxide Nanoparticles to Increase UV Lamp Life, Improve Efficiency of Photocatalysis and Lower Operating Costs

Model Broad Agency Announcement (BAA)
Fabutech Development Co. Ltd. (Wanchai, HK) Shi Guang Yang, Jian Cheng Wang and Wai Man Chan developed an UV lamp, which starts more quickly and has increased brightness and lifespan thanks to nanoparticles of titanium dioxide (TiO2), according to U.S. Patent 7,635,951.

In order to solve the technical problems that led to short life and low brightness encountered by other UV lamp manufacturing methods, a "U" shaped UV lamp  was developed made with a glass shell, and an electrode on each end of the lamp in which each electrode is coiled and in the shape of a hollow cone.

The lamp is long and thin, which allows the working voltage to be high while the current remains low. This decreases the energy consumption of the electrode and the self-absorption rate of the electric particles during gas discharge. The hollow conical electrode requires less heat than an electrode of the same mass and therefore allows the lamp to start more quickly and decreases the emission loss when the glow discharge is transformed to the arc discharge of the electrode.

The surface area of the coiled wire electrode is larger than that of a common wire electrode of similar type. As such, the emission loading is evenly distributed on the emission surface. Unlike common UV lamps, the emission loading is changed from point emission to surface emission, thus decreasing the electron scattering and allowing the lamp to resist the fierce impact from positive ions. The lamp in an embodiment of the present invention is thereby more efficient, brighter, and longer lasting than prior art lamps.

The lamp also has an ozone resistant layer covering the outer surface. This layer is made of nano-materials such as nano-TiO2, and while the lamp is on, the concentration of ozone is controlled, and meanwhile it can improve the efficiency of photocatalysis of the UV lamp and can improve its sterilizing ability. This element of an ozone resistant layer can improve the usefulness of the lamp in the photocatalysis field.

There are generally two kinds of UV lamps: cold-cathode lamps and hot-cathode lamps. Hot-cathode UV lamps have the disadvantages of being bulky, having short life spans, being unstable, having low radiant intensity, and decreasing in radiant intensity over time because the coating of the filament oxidizes so quickly, evaporates and peels off. Cold-cathode UV lamps have a higher resistance to damage from shaking and longer life spans than hot-cathode UV lamps. Cold-cathode lamps have been used in many types of liquid crystal displays (LCDs), scanners, and other such technologies because of its symmetrical, high intensity radiance and the fact that they can be made into very fine objects of various shapes.

Cold-cathode lamps are very bright and highly efficient. They also consume a lower amount of energy and have a long life span. Furthermore, cold-cathode lamps have good resistance to damage from shaking. Such lamps can restart easily and start even in lower temperatures. Compared to hot-cathode lamps, cold-cathode lamps emit less heat, are smaller in diameter, and can be used as the lighting source for LCD screens.

Conventional cold-cathode UV lamps are comprised of a glass shell, an electrode that is set on the end of the lamp, and a fluorescent coating on the inner surface of the glass shell. The emitting ability of prior art lamps is not very good because of the dispersion and scattering of electrons which do not allow for greater brightness. The brightness of the lamp depends on the amount of electric current applied to it; in this way, an increase in temperature affects the life of the lamp.

The typical rated life spans of cold-cathode lamps are about 20,000 hrs, but the actual life span is much shorter due to variables such as number of times lamps are switched on and off as well as operating temperature. In addition, since the thermal requirement of the electrode is significant, (i.e. the electrode needs to be heated up enough to vaporize the mercury inside the lamp) the lamp requires some time to start after an electric current is applied.

The use of TiO2 nanoparticles in the UV lamp solves many of the limitations encountered by UV lamps using other materials, according to inventors Shi Guang Yang, Jian Cheng Wang and Wai Man Chan.

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