a signal transmission mechanism configured to transmit a first signal in a case that a height of the free end portion is lower than a reference position which is set at a position higher than the stand by position, and to transmit a second signal which differs from the first signal, in a case that {HEAD ~ the height} of the free end portion is not less than {TAIL ~ the reference position} 
is not less than
a signal transmission mechanism configured to transmit a first signal in a case that a height of the free end portion is lower than a reference position which is set at a position higher than the stand by position , and to transmit a second signal which differs from the first signal , in a case that { HEAD ~ the height } of the free end portion is not less than { TAIL ~ the reference position }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL