Abstract: Disclosed is a roller offset printing apparatus which comprises image sensors 14 and 15 disposed on a linear stage 4, and position correction motors 8 to 13 disposed in the respective peripheries of a master plate 6 and a work plate 7, wherein positions of the master plate 6 and the work plate 7 on the linear stage 4 are detected by the image sensors 14 and 15 so that the respective positions of the master plate 6 and the work plate 7 are corrected by the motors 8 to 13 in accordance with the quantities of displacement when there is any displacement between the detected positions and reference positions. After correction, the linear stage 4 and a roller transfer drum 1 are moved while being synchronized with each other to thereby perform transfer. As a result, accuracy in positioning of the master plate and the work plate on the linear stage is improved, so that good superposition printing is provided.

Abstract: This invention relates to an aligning structure for aligning pin-receiving holes on a screen frame used in screen printing relative to upright pins mounted on a pin bar. The aligning structure, includes a pair of plates clamped on the frame. A first plate has an upright-pin-receiving hole to slidably receive the upright pin. A second plate has an upright-pin-receiving hole substantially larger than the upright pin. If the upright pin is received by both upright-pin-receiving holes and the clamp is loosened, the two plates can slide relative to each other to reposition the upright-pin-receiving hole relative to the screen frame. Retightening the clamp maintains the new alignment.