Driving Pressure Wave Shape for Drop Ejector
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
The drive signal in a drop-on-demand ink jet printer is selected to provide the optimum pressure wave in the fluid channel that leads to the nozzle. The active element in the channel is a piezoelectric tube which changes diameter when excited by the drive signal. Reflections from the reservoir end of the channel are minimized by an energy dissipative screen. The drive signal produces a pressure wave designed to accelerate a column of ink out the nozzle, break off the column of ink to form a drop, and draw the remaining ink back into the channel through the nozzle without also drawing air into the channel. The drop ejector is shown in Fig. 1. Piezoelectric tube 10 contains an active region 12 having a length L. When the drive signal in Fig. 2A is applied to this active region, the pressure wave in Fig.