An improved apparatus for checking a plurality of printer nozzles in a printer device comprises: a print head comprising a plurality of nozzles; a means for detecting at least one droplet of ink ejected from at least one nozzle of said plurality of nozzles; and a means for performing a sequence of measurements on a first output signal of said detecting means, wherein a determination of performance of said print head is made by analysing detected output signals produced by one or a plurality of ink droplets passing the detector, the one or plurality of ink droplets containing a predetermined minimum volume of ink, and said sequence of measurements being measured at a plurality of time intervals.