Hiroji Kumagai

Title: Hiroji Kumagai: Innovations in Lithographic Printing

Introduction

Hiroji Kumagai is an inventor associated with Narashino, Japan. His recorded work includes 4 patents focused on lithographic printing plates and dry planographic printing technology.

Latest Patents

Kumagai’s patent, “Lithographic Printing Plate,” describes an electrophotographic plate designed to address limitations of conventional zinc oxide master papers and provide practical sensitivity to long-wavelength laser light. The plate uses a photoconductive layer containing a mixture of phthalocyanine pigment, zinc oxide, and zinc sulfide dispersed in a binder resin. The process charges the plate, exposes it to an image, develops the resulting latent image with ink-receptive toner, and fixes the developed plate.

His “Dry Planographic Printing Apparatus” patent describes a system that charges and image-exposes a photosensitive plate, then develops and fixes it using conductive toner. The apparatus transfers toner to a sheet, fixes it, and delivers the printed material. It also includes mechanisms for feeding the photosensitive plate and removing the printing plate after a specified amount of printing.

Career Highlights

Kumagai’s listed company affiliations include Toppan Printing Co., Ltd. and Toyo Ink Mfg. Co., Ltd. His patent work reflects an emphasis on electrophotographic processes and practical improvements to planographic printing.

Collaborations

His listed coworkers include Tsutomu Naganuma and Kaneki Yoshida, who are associated with his work in printing technology.

Conclusion

Hiroji Kumagai’s recorded inventions address key stages of lithographic and dry planographic printing, from photosensitive plate preparation to toner development and printed-sheet delivery.