{HEAD ~ The print head unit} 1, wherein the parallelism adjusting means comprises at least one piezoelectric motor and at least one capacitive sensor, and the at least one piezoelectric motor is configured for actuating the first print head and the second print head by closing {TAIL ~ a loop} with the at least one capacitive sensor 
{ HEAD ~ The print head unit } 1 , wherein the parallelism adjusting means comprises at least one piezoelectric motor and at least one capacitive sensor , and the at least one piezoelectric motor is configured for actuating the first print head and the second print head by closing { TAIL ~ a loop } with the at least one capacitive sensor
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD 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 TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH