A rotary frame construction for web transport control devices, includes a carrier frame and a rotary frame in parallel therewith and carrying input and output rollers for a web and pivotably mounted on the carrier frame about a rotation center defined by control surfaces of one frame, the control surfaces scanned by cam followers on the other frame, the frames held in parallel alignment by support rollers on one frame and run surfaces on the other frame, the frames pivotally connected with one another by a drive system, the control surfaces constituted by three control curves formed at outer edges of a cam plate rigidly held on one frame, two of the control curves located on one side of the cam plate and the third on the opposite side of the cam plate, and the other frame has three cam followers respectively associated with one of the control curves.

A sheet conveying device includes a conveyor for conveying a sheet along a predetermined conveyance path and a feeder unit for supporting the sheet to be fed to the conveyor. The conveyor includes a first guide part for guiding the sheet toward a downstream side in the conveying direction in a direction inclined at a downward gradient, a second guide part for guiding the sheet from the first guide part toward a further downstream side in a direction inclined at an upward gradient, a suction roller arranged at the first guide part for conveying the sheet supported by the feeder unit toward the downstream side, and a first conveyance roller arranged at the second guide part and for conveying the sheet conveyed by the suction roller toward the downstream side one at a time.

A printing apparatus includes a first path conveying a printing medium from a manual-feed stacking unit to a printing unit; a second path converging with the first path at a converging section and conveying a printing medium from a cassette; a first roller pair provided downstream of the converging section on the first path to nip and convey a printing medium; a first detection unit detecting a printing medium stacked on the manual-feed stacking unit; a second roller pair provided downstream of the first roller pair on the first path to nip and convey a printing medium; a second detection unit arranged between the first and second roller pairs to detect a printing medium; and a control unit performing control to start feeding of the printing medium to the printing unit by the first roller pair if the first detection unit detects the printing medium but the second detection unit does not.