A method can reduce the scan time. According to width of the scan file waiting to scan it sets up the sensitive component as the forepart pixel zone, active pixel zone and back end pixel zone. It takes out the induced charge in forepart pixel zone and the induced charge produced against the each scan line in the active pixel zone. The induced charge produced against each scan line in the back end pixel zone is transferred into the forepart pixel zone for putting together with the induced charge produced against a next scan line in forepart pixel zone. It processes the induced charge produced against each scan line in the active zone into segment image, and collects them into whole image being relative to the waited scan file.