How Piezoelectric Inkjet Printing Works

Preamble: The method of projecting writing fluid droplets from an orifice…

Elements required (1)

1. A

   defining a confined volume of writing fluid, providing an ink reservoir in constant communication with said volume, and suddenly reducing the volume to project droplets from said orifice towards an associated printing medium, one droplet being projected out of said orifice each time said volume is suddenly reduced and wherein the printing rate is between 100 and 3,000 droplets per second. 2. A fluid drop projection means comprising a fluid chamber, an orifice communicating with said fluid chamber, means communicating with said fluid chamber for feeding fluids into said chamber, and volume displacement means responsive to electrical signals for displacing a predetermined volume of fluid in said chamber to eject from said orifice a single droplet of fluid, said volume displacement means including a piezoelectric plate which is deflected into said chamber to displace a volume of fluid responsive to electrical signals applied thereto, said piezoelectric plate being comprised of two transverse expanding piezoelectric plates secured to one another and arranged to expand transversely in opposite directions whereby to deflect responsive to electrical signal applied thereto. 3. Apparatus for recording with writing fluids on a recording medium, comprising: a writing fluid chamber formed by walls of a housing, at least a portion of one wall including two transversely expanding piezoelectric plates secured to one another and arranged to expand transversely in opposite directions in a manner to deflect into said fluid chamber in response to electrical energy applied to said piezoelectric plates, a passage in another wall of said writing fluid chamber communicating between the fluid chamber and an orifice on an outside surface of said another wall of the housing, a fluid reservoir in constant fluid communication with said fluid chamber for supplying writing fluid to said chamber, means for applying electric control signals to said piezoelectric plates to cause said plates to deflect inward into said writing fluid chamber to expel a single fluid drop to the outside of said fluid chamber through said orifice each time an electric control signal pulse is applied thereto, means disposed opposite of said orifice for holding said recording medium to receive drops of writing fluid discharged through said orifice, and means for providing relative movement between said housing and said recording medium, whereby a pattern of fluid droplets may be selectively recorded on said recording medium.