Thermal printer feed status sensor - detects single sheets based upon outputs from optical sensors along sheet edges and in centre

摘要

The thermal printer has single sheets feed along a track and under the print head unit. Motion across the head (6) is provided by a roller contact unit. The accurate positioning and orientation of the sheet is provided by optical sensors. Two of the sensor (15, 16) are located at the edges of the sheet track and indicate an error in a direction perpendicular to the feed direction. A second pair of optically reflective sensors (17, 18) detect the sheet along the direction of travel. ADVANTAGE - Rapid and accurate determination of sheet position.