Printing unit of the improved type and inkjet printing device comprising said printing unit

Printing unit (1) according to any of the claims from 2 to 4, characterized in that said at least two emitter elements (81) are constituted by four permanent magnets (91, 92, 93, 94) arranged on the four corners of one of said two surfaces to be chosen between said nozzle plate (21) and said cleaning surface (41) and said at least one measuring element (82) is constituted by two Hall effect proximity sensors (95, 96) arranged on the two corners of one end (21a, 41b) of one of said two surfaces to be chosen between said cleaning surface (41) and said nozzle plate (21).

Printing unit (1) according to any of the claims from 1 to 4, characterized in that said proximity sensor means (8) comprise a proximity sensor of the inductive type.

Printing unit (1) according to any of the claims from 1 to 4, characterized in that said proximity sensor means (8) comprise an ultrasonic proximity sensor.

Printing unit (1) according to any of the preceding claims, characterized in that said proximity sensor means (8) are configured to simultaneously measure said distance (6) in at least two different points of said nozzle plate (21) mutually spaced in the direction of the longitudinal axis (β) of said nozzle plate (21).

Printing unit (1) according to any of the preceding claims, characterized in that said movement actuator means (7) are operatively associated with said cleaning station (4) to perform the translation of said cleaning station (4) with respect to said printing head (2) from said first position to said second position.

Printing unit (1) according to any of the preceding claims, characterized in that said movement actuator means (7) are NC electric movement actuator means.

Method for carrying out the printing head cleaning operations through a printing unit (1) according to any of the claims from 1 to 12, comprising the following steps:

• arranging the printing head (2) at least partially overlapping the cleaning station (4), so that the nozzle plate (21) and the cleaning surface (41) face each other at least partially at a predefined distance (6);
• performing the relative translation of said printing head (2) and said cleaning station (4) from a first position, in which said suction element (5) is superimposed to a first end (21b) of said nozzle plate (21), to a second position, in which said suction element (5) is superimposed to a second end (21a), opposite said first end (21b), of said nozzle plate (21) and vice versa, so as to carry out said cleaning operation,
• characterized in that it includes the step of measuring said distance (6) in said first position and in said second position during said cleaning operation.

Printing device of the type ink jet for printing on the surfaces of electronic circuit boards, characterized in that it comprises a printing unit according to any of the claims from 1 to 12.