Abstract: An apparatus mounted in a vehicle having a door, a door detecting means, a driving detecting means, and a door control means. The door has an open position and a closed position. The door detecting means detects a condition of the door, and the driving detecting means detects a driving condition of the vehicle, that is whether the vehicle is running or stops. The control means controls the door to close and controls to announce that the door is closing, when the door is open and the vehicle is running. On the other hand, when the door is closed and the vehicle is running, the door is prevented from opening and “the door is prevented from opening” is announced. Since a clearance between the door and other parts caused by vibrations of the apparatus during running does not increase, a durability of the apparatus is high.

Abstract: A mobile unit communication control method is for exchanging information accurately between a plurality of responders and a questioner in a communication area without information drop-off. A ground unit constituting the questioner transmits an inquiry signal. A vehicle-mounted unit constituting the responder stores and returns the current time the vehicle-mounted unit first received the inquiry signal as a starting time. The ground unit selects a vehicle-mounted unit with the earliest starting time as an object of communication among a plurality of the vehicle-mounted units. A vehicle-mounted unit expected to pass the communication area at the earliest time is selected, and the ground unit transmits a response signal for handshaking with the particular vehicle-mounted unit, to which the vehicle-mounted unit replies. With the establishment of the handshake, data are exchanged between the ground unit and the vehicle-mounted unit.