The H countdown circuit 14 counts clocks of the internal clock, and generates an H reset signal which is {TAIL ~ a pulse} indicating {HEAD ~ one horizontal period} 
The H countdown circuit 14 counts clocks of the internal clock , and generates an H reset signal which is { TAIL ~ a pulse } indicating { HEAD ~ one horizontal period }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD