They have been investigated for use as photoreceptors in electrophotography. It uses a proprietary printing process called Liquid Electrophotography, or LEP for short. High-voltage electrophotography soon became known to the general public as Kirlian photography. This effect revolutionized electrophotography, which is the technological basis of today's office copying machines. It was the expense and inconvenience of photostats that drove Chester Carlson to study electrophotography. Over the next five years, the institute conducted experiments to improve the process of electrophotography. Electrophotography is currently not used in printed electronics. On October 6, 1942, the Patent Office issued Carlson's patent on electrophotography. Through the 1950s, over half the money Battelle spent developing electrophotography came from government contracts.