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