Thus, {TAIL ~ a touch point C} in the detecting area 219 can generate {HEAD ~ a mirror point C1} 
Thus , { TAIL ~ a touch point C } in the detecting area 219 can generate { HEAD ~ a mirror point C1 }
OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD