Improving the image quality and speed is an endless demand for printer applications. To meet the market requirements,
we have launched the world first laser printer (DocuColor 1256 GA) introducing 780-nm single-mode 8×4 VCSEL
arrays in the light exposure system in 2003. The DocuColor 1256 GA features 2400 dots per inch (dpi) resolution which
is the highest in the industry and a speed of 50 pages per minute (ppm). A VCSEL array design has an advantage that it
can increase the pixel density and also increase the printing speed by simultaneously scanning the 32-beam to the
photoconductor in the exposure process. Adopting VCSELs as a light source also contributes to the reduction of the
machine's power consumption. The VCSELs are industrially manufactured based on the original in-situ monitored
oxidation process to control the oxide aperture size. As a result, uniform characteristics with a less than 5% variation in
both output power and divergence angle are obtained. Special care is also taken in the assembly process to avoid
additional degradation in performance and quality. This technology is currently extended to high-end tandem color
machines (2400 dpi, 80 ppm) to grasp on-demand publishing market. This paper will cover the key technologies of the
VCSEL based light exposure system as well as its manufacturing process to assure its quality.
Japanese Ultimate Flatness Interferometer (FUJI) is a Fizeau type flatness interferometer that is capable of measuring flatness over 310 mm diameter. The concept and technologies applied to FUJI are explained. To demonstrate the performance of FUJI, an international comparison was held with Australia, and the difference of two independent measurements were smaller than four nanometers.