Pixel order and line signal of
the SK22500CNEC-XC Sensor
Line scan cameras are designated according to the number of line sensors as triple line, dual line or single line sensors. Schäfter+Kirchhoff offers most camera models with triple line sensors.
Triple line sensors have three separate rows of sensors for the primary colors red (R), green (G) and blue (B). The positions of the R, G and B pixels are defined precisely and triple line sensors exhibit particularly high resolutions. The distance between the line sensors (line spacing) is generally 1, 2, 8 or 9-times the pixel height (h). This spatial distance in the translational direction is automatically corrected during production of the image. For exact color mixing, line synchronous image acquisition according to formular F1 and the direction of transport are particularly important. The color information of a picture with a delay line, Ld, of cycles is incomplete. The line delay Ld is twice the line spacing LS divided by the pixel height h, with both usually measured in microns:
Ld = 2 LS / h
Applications in which the transport velocity is not exactly known, such as when imaging bulk products, during free-fall or a photo-finish in a race, should use color line scan cameras with a low line spacing. This has the added advantage that the color convergence errors from the not fully-synchronous signals are smaller and may be neglected.