In 2006/7 there has been a surge in patents filed by Matsushita on printed and potentially printed electronics. The effort covers an impressively broad range of activity including laminar batteries and the newer thin film photovoltaics based on inorganic compounds. Matsushita patents on organic electronics date back to 1991, far earlier than those of other organisations. Priority has not been OLEDs because they are covered by the Toshiba-Matsushita joint venture, but a range of devices including electroactive polymers and thin film transistors.
Electroactive polymers change shape under an electric field and can be used for micropumps, reprogrammable Braille, packaging that alerts the owner and many other applications, including where stretchable electronics is printed on the surface, as in the work on e-skins at Tokyo University and elsewhere.
Preparing to produce printed transistor circuits
Matsushita's patent filings on printed and potentially printed electronics were modest in number up to the start of 2006 when they surged, notably concerned with high performance printed transistors.
Clearly the company is preparing to manufacture printed transistors and its intellectual property covers a range of options for this. For example, patent EP1650809 concerns printed transistors employing composites consisting of inorganic particles in an organic semiconducting layer.
Patent EP1684360 concerns a thin film transistor where the conjugated organic semiconductor molecules are oriented so the orbitals substantially oppose each other and the molecular axis of the main chains is oriented to be inclined in respect to a direction of electric field in a channel layer in the semiconducting layer.
However, in 2006/7 the bulk of the Matsushita transistor patents relate to manufacturing technology. The Japanese are acutely aware that the Europeans, such as Plastic Logic, are commercialising printed transistor circuits ahead of them and they do not intend for this to be the case for long.
For example, Sony and Toppan Printing are racing to commercialise flexible printed electrophoretic displays in direct competition with Plastic Logic. The Sony product will probably have an organic transistor array as backplane driver whereas Toppan Printing has opted for printed inorganic transistors.
After all, transistors are set to be the biggest selling printed electronics product of all. Matsushita is also putting a major effort into making flexible plasma displays and this may use some printing technology.
This major quoted company is Japan's largest consumer electronics company. It consists of 600 companies marketing 15,000 products. World's largest domestic electronics company with the Panasonic, National and Technics brands etc.
Matsushita Battery Industrial Co Ltd has been studying printed photovoltaics for some time. For example, as long ago as 1986, it reported "Long-term reliability tests have been carried out screen-printed CdS/CdTe solar-cell modules under rooftop conditions in three countries at different latitudes (Japan, India and Australia).
Test results on 118 modules, over periods of 140 to 800 days, have shown that such modules are fundamentally stable under these conditions. The only exception was one large module tested in India. The degradation of this module appears to have resulted from water which was able to enter because of poor sealing. Studies on waterproofing are necessary if the long-term reliability of screen-printed CdS/CdTe solar-cell modules is to be improved."
Matsushita Electric Industrial
For further information read Printed Electronics in East Asia