Abstract: A vacuum cleaner is selectively operable in one of three modes, namely: an automatic self-directing mode, a remotely controlled mode, or a manual mode. The vacuum carries ultrasonic object detectors for detecting walls of a room being cleaned, as well as obstacles in the room. When in a self-directing mode, the vacuum selects a path of travel based upon a detected wall of the room as a reference, and steers itself to avoid obstacles in its path. An electric cord is automatically payed-out and retracted as the vacuum travels. A constant tension is imposed on the cord as it is payed-out or retracted by an appropriate manipulation of a spiral spring connected to the cord.

Abstract: A microwave oven includes a cooking chamber in which a turn table is disposed for rotation about a vertical axis, and vertical up/down movement along the axis. The turn table has an axle extending downwardly therefrom along the axis. The lower end of the axle rests on a cam surface of a rotary cam member whereby the cam surface causes the axle (and thus the turn table) to alternately move up and down when the rotary cam member is rotated by a first motor. A second motor is connected to the axle to simultaneously rotate the axle and turn table. A traction member is fixed to the rotary cam and overlies a portion of the axle. The traction member extends along a portion of the cam surface which causes the axle to move downwardly, whereby the traction member can pull the axle downwardly if the axle does not properly gravitate downwardly.

Abstract: An automatic self-propelled vacuum cleaner includes an electrical power supply cord having a plug. The plug carries latches which can be coupled to either the vacuum cleaner or a wall-mounted socket. The vacuum cleaner carries a light beam receiver which receives a light beam signal emitted from the socket for guiding the vacuum cleaner toward the socket.

Abstract: A microwave oven includes a cooking chamber and a turntable disposed therein for supporting food. The turntable is rotatable about an axis and is vertically adjusted. A single reversible motor performs both functions of rotating and vertically adjusting the turntable due to a power transmission mechanism which connects the motor to the turntable and rotates the turntable in response to the motor being driven in a first direction, and for vertically moving the turntable in response to the motor being driven the opposite direction.

Abstract: The present invention relates to a charging apparatus for a robot cleaner and a method for charging the robot cleaner by which the robot cleaner can be accurately induced to a power source supplier to receive a battery charge when a battery power source drops below a predetermined level. The apparatus includes a control unit for controlling an overall operation, a memory which stores a driving program including structures for various rooms for which cleaning operations may be performed, and a driving unit for moving the robot cleaner in forward, reverse, left and right directions according to control signals of the control unit. A travel distance detecting unit is provided for detecting a travel distance covered by the driving unit and a travel direction detecting unit is provided for detecting a travel direction varied by the driving unit.

Abstract: A constant tension is maintained on cord of a robot by determining whether the cord is being extracted or retracted and the extent of such extraction or retraction, and increasing or decreasing a spring force applied to the cord by an amount suitable for maintaining a constant tension on the cord.