What did you think when you first heard that Canon planned to produce a commercial printing press? Even then, Canon copying machines were already able to produce high-quality images. To most people, it seemed that the image quality was already more than good enough, don't you think?
- Kameda
- In commercial printing, what the customer is "buying" is actually the printed material. From that perspective, the image quality of the copiers we had at that time was not quite up to the task.
Also, with copiers, until now they were fine as long as they could print on plain paper, but in publishing you have to be able print on all kinds of media, including coated papers. So from that point of view, there was no way that we could offer the products we had at the time to the commercial printing market.
- Hirobe
- At the time, I was in charge of the copying machine that had the highest color output speed at Canon. But compared to copiers, printed matter was like another dimension entirely. I thought it would be impossible to achieve that level.
First of all, the size of the toner particles was extremely important. We cleared a significant technical hurdle in developing Canon's first color toner with an average particle size of 5.5µm.
On the development side too, everyone knew that if you made the toner smaller the image quality would improve. There had been many attempts at doing this over the years, but the obstacles had been too large. Even so, we demanded that the toner team come up with a color toner that solved all these problems. We told them that if we didn´t overcome that obstacle first, the whole project was a non-starter. (Laughs.)
"Numerically it is only a question of 2-3µm, but that difference is quite a large one. Given the technology we had then, it was completely impossible."(Fujikawa)
So it was half a threat then? (Laughs.) As the developer in charge of toner, Mr. Fujikawa, that meant that right from the start the responsibility for the success of whole project lay on your shoulders. What did you think when you heard that?
- Fujikawa
- Today, of course, 5.5µm is the standard size for color toner particles, but at that time it was 7-8µm. Numerically it is only a question of 2-3µm, but that difference is quite a large one. Given the technology we had then, it was completely impossible. But when they showed me the images that were our goal for the press, I felt, "We've got to do this!"
You said it was impossible with the technology you had then. Was there a reason it was impossible to make the toner smaller?
- Fujikawa
- With the toner in this product we control the particle size through a pelletization process, but with the technology we had then there were problems with producing the toner in commercial quantities, and with the electrophotographic quality.
So how did you solve those problems?
- Fujikawa
- In order to produce the toner in commercial quantities, we made upgrades to almost all of our toner production equipment.
- Hirobe
- In terms of electrophotographic quality, the image quality had to be raised much higher, but in order to do that, we had to increase the laser resolution to 1200 dots per inch (dpi), a first-ever for Canon. We were attempting to achieve a higher level of technology than anything we had done before in terms of image processing. The resolution we had at that time was 600 dpi, which meant we were doubling it.
Let´s say you draw an image with 600 x 600 dots inside a one-inch square. If you are off by one dot, the image shifts by about 40µm.
When the number of dots is doubled to 1200 dpi, the amount of shift caused by a one-dot error is smaller, and you can create a finer image. In order to create a finely detailed image, we used a high-resolution laser.
