Abstract: A stack accessory for a printer attaches as a module to a printer and provides a source of media. Media originates from a stack within the module passing media from the bottom of the stack to the printer. The top of the stack remains open to replenish the media stack without interrupting printing operations. The stack accessory serves particularly well as an envelope feed mechanism supporting a large inventory of envelopes therein. Large scale and continuous envelope printing operations result. Overall, a stack accessory under the present invention converts a generally conventional printer into a high-volume printing device enjoying uninterrupted printing operations associated with replenishing a supply of media fed therethrough.

Abstract: A large type printer which continuously drives annular printing wheels having circumferentially spaced printing facets on their peripheries. The driving mechanism is a friction drive which may be overriden. Thus, the apparatus includes means for monitoring the rotational positions of each of the printing wheels and for stopping the rotation of the individual printing wheels when the respective facets are in printing position.