Time correction system for multi-nozzle ink jet printer

Abstract

In an ink jet nozzle per spot printer, the transit time of each stream is measured on a periodic basis. In response to the measured transit times, the time at which information imparting signals are applied to the respective charge electrodes is controlled. The transit time is measured (counted) in units of a drop cycle. The slowest count is detected, and the difference is taken between the transit time of the slowest stream and all other streams. In the instance when there is a transit time difference of zero between the slowest stream and a given stream, the printing signal is provided to the charge electrode without delay. In the instances when a transit time difference is detected, an information imparting signal is applied to the charge electrode with a delay dependent upon the sensed transit time difference. A data register has information signals stored therein which are indicative of the data to be printed. Such data will be printed during an appropriate portion of a data cycle. The data cycle is broken down into several drop formation periods, any one of which can be used to provide a delayed information signal by means of a correction register. The correction register has data stored therein indicative of whether the information stored in the data register is to be applied to the respective charge electrodes during a specific drop formation period. An output register responds to inputs from the data register and correction register for passing the information imparting signals to the respective charge electrodes in the proper timing sequence.