An on-demand power take-off unit is equipped with a dual-mode bi-directional overrunning clutch and a shift mechanism to establish on-demand and part-time four-wheel drive modes. The mobile electronic device includes an image projector that projects an image, a detector that detects a specific change in an irradiation area of light irradiated from the image projector or in a predetermined area including the irradiation area, and a control unit that controls the operation of the image projector. The request includes data identifying a target application and a target application service requested by the requestor. In the monopulse radar system of the present invention, calibration work is simplified and an angular correction can be automated. The scan confirmation sheet indicates that the computerized device received the scan job. A pair of paper guide members are disposed in the vicinity of the lateral ends of the ink ribbon drawn from the ribbon outlet port respectively so as to project from the wall plate of the cassette body in the direction in which the ink ribbon is drawn.