Abstract: The rotary driving device includes a shaft which has one end and the other end in the axial direction and is provided with an oil passage through which lubricating oil flows from one end to the other end, a transmission case accommodating the shaft therein, and a bearing arranged at the other end of the shaft in the transmission case and rotatably supporting the shaft. The shaft includes an end surface located on the other end in the axial direction. The transmission case includes an opposing surface facing the end surface with a gap therebetween in the axial direction. One of the end surface and the opposing surface is provided with a groove so as to generate a negative pressure on the other end when the shaft rotates.

Abstract: A paper tray control system includes a recording apparatus for recording image data on a paper, to which additional devices are attachable; a paper tray installed in the recording apparatus as the additional devices for stocking the paper on which the image data has been recorded; and main controller for controlling the recording apparatus and for generating an instruction. The paper tray control system is further provided with a tray control separated from the main controller for controlling the paper tray; and a communication line connected between the main controller and the tray controller, wherein the tray controller receives the instruction from the main controller through the communication line to control the paper tray according to the instruction.