DOT SENSING, COLOR SENSING AND MEDIA SENSING BY A PRINTER FOR QUALITY CONTROL

摘要

A print monitoring approach is provided in which sequences of irregular two-dimensional frames of image information are captured at a resolution sufficiently high to enable details of individual droplets to be identified. The approach may be used to monitor individual droplets deposited on a medium (18), such as a sheet of paper, by an inkjet printhead (16, 94 and 96). An optical detector (26, 32 and 92) having an irregular two-dimensional array of closely spaced sensor elements (56) is mounted for movement with the inkjet printhead or other print assembly. A processor (60) is responsive to the image frames from the optical detector to adjust print quality parameters when the physical characteristics of the imaged droplets are detected as being outside of a preselected range of acceptability. The physical characteristics that are resolved may include gyrational information or different droplet position information. Optical dot gain can also be measured.