Katsuo Sakai

Multilayer OPC for one-shot two-color printer

The author has developed a novel multilayer OPC for a one-shot, 2-color printer, and called it the 2-color OPC. It consists of 3 main layers: an upper OPC layer, middle thin-hole trapping and solvent-blocking layers, and a lower OPC layer. The upper OPC has high sensitivity to 680 nm and the lower OPC has high sensitivity to 780 nm. The following steps are used for a one-shot, 2-color print using the 2-color OPC: (1) positive charge under red light; (2) negative charge; (3) image exposure by 680 nm and 780 nm laser beams which produce two different (plus and minus) latent images. Development, transfer, cleaning, and fixing are then about the same as in the conventional process. In the first charge step, many photo-induced holes traverse through the upper OPC to the hole-trapping layer where they are firmly trapped throughout the other steps. This hole-trapping capability is the key technology and the feature distinguishing this printer from ordinary OPCs. The hole-trapping layer is newly designed for this purpose. If, however, many holes are trapped in shallow traps in the upper OPC midway to the hole-trapping layer most of them will be released at the second charge step resulting in the production of a low (poor) latent image. The authors studies on where holes are trapped, using three different methods, revealed that almost all are trapped in the hole-trapping layer as intended.

Two -color PPC and Its Techniques

This paper outlines the technical trend toward 2-color plain paper copiers (PPC) and new improvements in a double layer 2-color organic photoconductor (OPC) by Ricoh.