Patent ID: 7613552

Claim:
Lawn-mower ( 1 ) comprising: a motor-drive ( 2 ), a cutting device ( 3 ), a presence sensor ( 4 ) for detecting a presence of an external mass within a predetermined distance which is greater than or equal to zero, a grass sensor for detecting regions of grass having a surface height that is indicative of an uncut region of grass that has not already been cut, and means for operating said lawn-mower ( 1 ) in response to receiving a signal from said grass sensor and said presence sensor ( 4 ), wherein said means for operating said lawn-mower controls operation of said motor-drive to direct said lawn-mower to said uncut region of grass and said presence sensor comprises an electronic proximity sensor that includes an oscillator comprising a metal-oxide-semiconductor (MOS) junction, wherein the oscillator provides an electric output oscillation in response to variations of an input signal.