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 {HEAD ~ the second print head} by closing {TAIL ~ a loop} with the at least one capacitive sensor 
by closing
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 { HEAD ~ the second print head } by closing { TAIL ~ a loop } with the at least one capacitive sensor
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