Abstract: A jet drop printing head comprises a transportable upper assembly and a lower assembly adapted for receiving the upper assembly in such a manner as to control the alignment between the two assemblies. A novel catcher mounting assembly permits ready operational positioning of a pair of catchers and easy downward swinging for inspection of the charge plate.

Abstract: A jet drop printing head comprises a transportable upper assembly and a lower assembly adapted for receiving the upper assembly in such a manner as to control the alignment between the two assemblies. The upper assembly, which is primarily a fluidics package, carries an orifice plate and fluidic elements for producing a jet-forming flow of printing liquid through a series of orifices in the orifice plate. The upper assembly also carries a set of three rests which have been prealigned for mating engagement with a set of precision machine balls mounted in a charge ring plate carried by the lower assembly. Upon assembly the three rests are readily received by the three balls, and the orifice plate orifices are brought into precise registration with corresponding apertures in the charge ring plate.

Abstract: An ink jet recorder has a means for forming streams of ink drops and a means for selectively charging the drops in the streams as they are formed. The drops pass through charge ring orifices which are lined with charge rings. Charging potentials are selectively applied to the charge rings to induce selectively charges in the drops as they are formed. In order to prevent a large deplating current from flowing between the charge rings in the event of an inadvertent short, a means for limiting current flow is provided. Current may be limited by a charge ring formed from a bulk resistive material such as an epoxy filled with conductive particles. Alternatively, current may be limited by discrete resistors positioned adjacent the charge rings and through which the charging potential is applied.