To stably read the colors of printed matter by the scanners, the distance between the paper and the scanners must be kept constant to stabilize the illuminance of the LED lighting on the paper. To achieve this, the transfer path of the IQ-501 is designed to bend the paper at the reading position of the scanners to prevent waviness of the paper, and minimize variations of the distance between the paper being read and the scanners by guiding the paper along the outside of the bending. In addition, to correctly read the printing position relative to paper, it is important to keep transferring paper at a constant speed to prevent images taken by the CCD sensors from shrinking. Thus, the speed of the rollers is controlled to increase along the feed direction toward the downstream side, thus preventing paper deflection in the feed direction inside the transfer path, and the paper is constantly scanned under tension. Thanks to all this, the difference in the speed of paper read by the two scanners can be kept below 0.1%.

As the state of the printing device changes during printing, printing misregistration occurs on the front and back sides of paper in duplex printing. High positional accuracy on the front and back sides of paper is required for commercial printing, and it is therefore necessary to adjust printing positions by detecting misregistration that occurred and feeding it back to printing data. The printing device prints a pattern for positional adjustment in the margin of the printing paper, and the difference between the position of the printed pattern and the target position of the pattern for positional adjustment is detected at any time from the image scanned by the IQ-501 in real time during printing. When the detected difference is fed back to printing data, the IQ-501 calculates a correction value by referring to the printing results on multiple sheets to extract the tendency of misregistration over time, and can thus perform stable adjustments on all pages. Color variations are also adjusted by printing a pattern for color adjustment and detecting the difference between the pattern and the color reproduction at the time of the pre-printing printer calibration (color adjustment) from the scanned image. The IQ-501 achieves high-accuracy color adjustments with the aid of an algorithm, which not only adjusts single colors of CMYK toner for digital photos but also monitors and adjusts variations of mixed colors using two-color or three-color toner.

Accurate colorimetry of color patches on paper is required to perform color management and thus print the colors as desired by the customer. To obtain accurate colorimetric data, a spectrophotometer is installed in the IQ-501. A spectrophotometer ensures accurate colorimetry but takes time to measure many patches due to its narrow measurement range. On the other hand, a CCD sensor has a wide measurement range and can measure many patches at a time. However, it cannot produce accurate colorimetric data because the data is affected by variations of the sensor and the characteristics of the paper. To resolve these issues, Konica Minolta has developed a hybrid colorimetric technology, which utilizes the advantages of a spectrophotometer and a CCD sensor and can perform accurate colorimetry of many patches at a time by correcting CCD sensors with the colorimetric value obtained from the spectrophotometer. A correction equation for the colorimetric data of the CCD sensors is derived from the difference in the colorimetric data on the same patch measured by both sensors. This technology enables customers to obtain accurate colorimetric data over the entire area of the paper.