A simple change in the geometry of piezoelectric transformers that can increase the conversion ratio without adding volume or weight may make possible thinner laptop computers and flat-screen TV’s say researchers at the University of Pennsylvania State University in the US.
Electromagnetic transformers consist of two coils of wire that convert high voltages to lower ones or low voltages to higher ones. The size of the step-up or step-down depends on the difference between the number of turns of wire in each coil. Large electromagnetic transformers are very efficient, but miniaturization decreases the efficiency. The Pennsylvania research team worked on disk-shaped transformers made of an enhanced piezoelectric material consisting of a lead, zirconium, titanium ceramic doped with manganese and cerium.
The screen uses most of the energy consumed by a notebook computer. The liquid crystal display uses fluorescent lights to backlight the screen and these lights take high voltage to turn on. Most portable computers run on 12-volt batteries, but it takes 500 volts to turn on the screen backlight, while it takes only 250 to 300 volts to continue their operation.
In the new design, transformers are made from piezoelectric materials by applying a chopped electric charge to one side of a piezoelectric wafer. This on and off charge creates a vibration in the material, which is converted to an ac current on the other side of the wafer.
Piezoelectric transformers are not only more efficient, smaller and lighter, but they are also much less expensive to manufacture than conventional coil wound transformers.