Print head of a continuous ink jet printer comprising, within a cover: - means (4, 4 1, 4 x, 4 n) for producing at least one ink or solvent jet; - means for separating the drops or sections of at least one jet, intended for printing, from the drops or sections that do not serve for printing; - a slot, open to the outside of the print head and enabling the drops or sections of ink intended for printing to get out; - an ink recovery gutter, for recovering the drops or sections of ink not intended for printing, said ink recovery gutter comprising an hollow ink recovery volume (12, 13) inside said gutter; - at least one conductive detection element (20, 20 i, 30, 30 1, 30 2, 120 1, 120 2), arranged inside the print head: ∗ against an interior surface of the cover; ∗ or against a surface of the recovery gutter, exterior to the ink recovery volume (12,13), said conductive element being able to receive overflows of ink from the ink recovery volume (12, 13) of the recovery gutter; ∗ or at a distance from the recovery gutter, between said recovery gutter and the cover or between said recovery gutter and the means (4, 41, 4x, 4n) for producing at least one ink or solvent jet; - means (16, 16i, 36) for detecting a variation in impedance of said at least one conductive detection element, when charged or non-charged ink or solvent is present in contact therewith or with a dielectric layer in contact therewith. - means (4, 4 1, 4 x, 4 n) for producing at least one ink or solvent jet; - means for separating the drops or sections of at least one jet, intended for printing, from the drops or sections that do not serve for printing; - a slot, open to the outside of the print head and enabling the drops or sections of ink intended for printing to get out; - an ink recovery gutter, for recovering the drops or sections of ink not intended for printing, said ink recovery gutter comprising an hollow ink recovery volume (12, 13) inside said gutter; - at least one conductive detection element (20, 20 i, 30, 30 1, 30 2, 120 1, 120 2), arranged inside the print head: ∗ against an interior surface of the cover; ∗ or against a surface of the recovery gutter, exterior to the ink recovery volume (12,13), said conductive element being able to receive overflows of ink from the ink recovery volume (12, 13) of the recovery gutter; ∗ or at a distance from the recovery gutter, between said recovery gutter and the cover or between said recovery gutter and the means (4, 41, 4x, 4n) for producing at least one ink or solvent jet; ∗ against an interior surface of the cover; ∗ or against a surface of the recovery gutter, exterior to the ink recovery volume (12,13), said conductive element being able to receive overflows of ink from the ink recovery volume (12, 13) of the recovery gutter; ∗ or at a distance from the recovery gutter, between said recovery gutter and the cover or between said recovery gutter and the means (4, 41, 4x, 4n) for producing at least one ink or solvent jet; - means (16, 16i, 36) for detecting a variation in impedance of said at least one conductive detection element, when charged or non-charged ink or solvent is present in contact therewith or with a dielectric layer in contact therewith.