Moving image scanner

Abstract

An image scanner for scanning a document along a plurality of scan lines and providing a plurality of print control signal pulses in response to the image density of the document along the scan lines includes a means for projecting a moving document image onto a focal plane and a sensor array positioned in the focal plane. The sensor array includes columns of sensors extending parallel to the direction of image movement and a shift register associated with each column for sensors for shifting electrical outputs from the sensors in the direction of image movement. In a line copy mode of operation, the electrical outputs are shifted at the same rate at the rate of movement of the image such that the given pixel on the image is scanned sequentially by each of the sensors in a column. The electrical outputs are compared with a predetermined reference label to produce a print control signal. In a gray scale mode of operation, the outputs from all of the sensors in a sensor column are accumulated to produce an output related to the average image density of the area scanned by the column of sensors. The electrical outputs resulting from successively scanning overlapping image areas are integrated until a predetermined reference level is reached to produce a print control signal.