This machine uses VCSEL technology. VCSEL (Vertical Cavity Surface Emitting Laser) is a two-dimensional array of 40 beams, with a resolution of 1200 x 4800 dpi. During two-sided printing, some paper may shrink or swell due to heat after passing through the fusing unit on the first pass. This small change in the paper size can cause inaccurate registration on the 2nd side. VCSEL compensates for this in two ways:
- Magnification correction (sub scan direction). Image magnification adjustment for the back side can be set by the operator. This feature is a new parameter in the Paper Library.
- Pixel clock frequency (main scan direction). The image can be adjusted front-to-back in increments of 1/48 of a dot, to avoid mismatch between front/back registration.
VCSEL also keeps the strength of the laser beams at a constant level by regulating the strength of the beams with optical waveform correction. This correction is especially important for the reproduction of thin diagonal lines.
The machine calculates the optimum optic settings for each color and uses an ND filter to adjust the settings.