The Canon NP Process
The basic technology behind electrophotography was invented by American physicist Chester F. Carlson in 1938. This was subsequently put to practical use by the U.S.-based Haloid Company (now Xerox Corporation) in the development of the world’s first plain-paper copier, introduced in 1959. Since then, electrophotography has gone on to become an important industrial technology employed in a variety of fields.
Canon began its full-fledged efforts in the field in 1962, and three years later, as conflicting technologies competed on a global stage, the company invented its NP approach.
Canon’s NP method differed from that of Xerox in that it did not use selenium as the photosensitive material. Instead, it opted for cadmium sulfide (CdS), a camera developer material already in plentiful supply at the company. A hard insulating coating was applied on top of the CdS to create a unique three-layer drum, achieving much higher levels of durability compared with the extremely delicate selenium-coated drums, which required regular maintenance.
In 1979, Canon broke with convention and did away with the concentration adjustment mechanism, essential for the two-component method that had been employed up to that time and made use of a conductive toner and iron powder. In its place, Canon announced the NP-
200J, which employed a dry mono-component jumping-development approach. This new method vastly improved the sharpness of copied images by accurately applying an insulating toner with a small particle size of several micrometers, or several millionths of a meter, onto the photosensitive drum. A range of advances and improvements enabled a simplified structure, including the implementation of a new optical system incorporating a Selfoc lens, made possible through the development of a new toner containing an extremely small amount of external additive, and the application of alternating current carrier voltage to the carrier during development, an approach that defied conventional thinking. As a result, it was
possible to achieve an extremely compact, low-cost design that enjoyed extraordinary popularity across the world.
Behind this success was Canon’s development culture, which wholeheartedly encouraged the tackling of any idea with potential, no matter how challenging it may be.
Comparison of the Dry Mono-Component Jumping Method and the Two-Component Method