Method of inspecting the nozzle discharge state, a discharge state inspection method, and a fluid discharge device

Abstract

A method of inspecting a discharge state of a nozzle prevents wrongly determining that discharge is normal even though fluid droplets are not discharged normally. In a fluid droplet discharge device such as an inkjet printer, a momentary induced current is produced when a charged ink dropletlands on a head capwith a potential difference. A voltage change detection unitdetects the induced current as a voltage change. A decision unitdetermines that the ink discharge state is normal if the maximum amplitude L of the voltage change detected by the voltage change detection unitin a first period S is greater than or equal to a first threshold value Q. If the amplitude of voltage change detected in a third period U after the specific period has passed goes to a second threshold value R, a decision cancellation unitdetermines that noise is contained in the voltage change. If the ink discharge state is determined to be normal and noise is determined to be contained in the voltage change, inspection is repeated and the normal discharge decision is cancelled.