the control circuit causes the transmission surfaces of the second combination of {TAIL ~ transmission elements} to vibrate in a substantially same phase so that the transmission surfaces of the second combination vibrate in an integral manner, and thereby, the ultrasonic wave with {HEAD ~ a third directivity} is transmitted from the transmission surfaces of the second combination of transmission elements 
the control circuit causes the transmission surfaces of the second combination of { TAIL ~ transmission elements } to vibrate in a substantially same phase so that the transmission surfaces of the second combination vibrate in an integral manner , and thereby , the ultrasonic wave with { HEAD ~ a third directivity } is transmitted from the transmission surfaces of the second combination of transmission elements
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL 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 HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH