Imaging Pioneering History - Long history of technological development -Creation of Revolutionary Printing Technologies through Imagination & Perspiration

Electrophotographic Technologies that Defy Conventional Thinking

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.

Comparison of the Dry Mono-Component Jumping Method and the Two-Component Method

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.

The Electrophotographic Printing Process

Laser printers / laser multifunction printers (MFPs), office multifunction devices (MFDs), and digital production printing systems all employ the same printing principle.

1 Charging

The photosensitive drum surface is negatively charged with a static charge.

2 Exposure

Laser beams scan the photosensitive drum to form an image. Areas exposed to the laser beams lose their electrical charge.

3 Developing

Toner is brought in close proximity to the drum and affixes to non-charged areas.

4 Transfer

The photosensitive drum is brought into contact with the paper* and a positive charge is applied from behind, transferring the toner onto the paper.

5 Fixing

Heat and pressure are applied to fix the toner to the paper.

  • *
    Most color models use a transfer system in which the toner first transfers from the photosensitive drum to an intermediate transfer belt, then from the belt to the paper.

All-in-One Toner Cartridge Breakthrough

1982 gave way to a revolutionary breakthrough in the way developers viewed copying machines. Previously, unavoidable regular maintenance made photocopiers seem unsuitable for non-business applications. However, the emergence of the all-in-one toner cartridge concept, enabling the replacement of the toner, drum, and all other major copier components in a single operation, and the development of related technology opened the market for home-use copiers. Canon's PC-10 / 20 and more advanced Family Copier models have had a major impact on electrophotographic technology, as well as the company's business, from manufacturing to marketing.

Passage of the Inkjet Approach from Concept to Conviction

The Soldering Iron and Syringe that Sparked the Invention

In the mid-1970s, Canon was among the first to recognize the true potential of inkjet technology, and proceed with the development of this technology. At the time, competition between Canon and a number of printer manufacturers to develop inkjet printing using piezoelectric elements led to Canon introducing a monochrome desktop calculator printer using piezoelectric elements in 1981. However, Canon continued to pursue a more advanced inkjet technology based on a new principle that could surpass printing using piezoelectric elements.
It was around this time that a fortuitous incident occurred. When an engineer was conducting an experiment, the tip of a soldering iron came into contact with a nearby syringe needle containing ink, causing ink droplets to spurt out from the tip of the needle. This was the moment that the idea of using heat became a firm belief. This led to a variety of experiments and tests, which in turn resulted in the creation of a proprietary inkjet technology that uses the heat from a heater to eject ink droplets. On October 3, 1977, Canon submitted a basic patent application for the world's first thermal inkjet (Bubble Jet) technology.

Canon's first inkjet printer

There were still, however, many hurdles that remained before this technology could be successfully commercialized, one of which was heater durability. Heaters located inside the microscopic nozzles that eject the ink are formed using semiconductor production technology. Even though moisture and electrolytes are the bane of semiconductor elements, Canon challenged conventional wisdom by bringing ink, which contains both of these elements, into contact with the semiconductor heaters in order to vaporize it. Persistent trial and error eventually led to the development of a thin, high-performance insulation layer that electrically insulated the heater and ink in a highly reliable manner and was also capable of withstanding the powerful shock resulting from the generation and expulsion of bubbles.
Thermal decomposition of ink components presented another major problem. Heating the surface of the heater to several hundred degrees in one-millionth of a second caused the ink to break down and denature, resulting in thermal decomposition and eventually making the efficient transfer of heat impossible. This phenomenon led to the coining of the term kogation — formed by attaching an English suffix to the Japanese word koge, meaning "scorch" or "burn" — an expression that went on to gain international acceptance. While the problem was thought by some to be insurmountable, the company, through the development of new analytic methods and the carrying out of massive amounts of repetitive testing, successfully found a solution to the problem of kogation. In 1985, eight years after submitting the original patent application, Canon launched its first Bubble Jet printer, the BJ-80.

Groundbreaking technology FINE using light to create nozzles

The FINE Nozzle

More than 20 years have passed since the introduction of the BJ-80. During that time, inkjet technology has evolved from monochrome to color, from text-centric output to graphics, and finally to photo prints. Achieving photo-quality printing demanded smaller ink droplets, a goal that posed multiple challenges. Of primary importance is the technology that makes possible the high-precision creation of several thousand nozzles. Previously manufacturers needed to assemble multiple precisely manufactured components to develop fine and complex inkjet nozzles. In principle, however, it is extremely difficult to assemble several thousand nozzles with a high degree of accuracy.
Canon wasted no time in precisely identifying the limitations of previous manufacturing conventions, and in 1992, initiated ambitious efforts to devise a revolutionary new production technology. Making full use of its photolithographic technologies employed in the production of semiconductors, the company successfully developed the world's first production method for highly accurate nozzles that did not rely on the bonding of separate components. However, this production method could not come to fruition using existing materials.
There, Canon developed original high-performance materials from a molecular level and introduced technology that could use these materials effectively. Using light to create the nozzles, this groundbreaking technology was christened FINE. Over the next seven years, it was carefully perfected before being market launched in 1999 as part of the BJC-8500. Later, Canon would go on to make further improvements to FINE, and it is now seen in a wide range of inkjet products. Offering outstanding image quality and speed, it marked a new chapter in the development of inkjet printers.