As indicated above the prior art sought to control the charge per unit mass of the toner and {HEAD ~ thus the calibration} of the printer using {TAIL ~ low field conductivity measurements} of the toner 
using
As indicated above the prior art sought to control the charge per unit mass of the toner and { HEAD ~ thus the calibration } of the printer using { TAIL ~ low field conductivity measurements } of the toner
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH