Browse Prior Art Database

Unimorph Drop Generator for an Ink Jet Printer

IP.com Disclosure Number: IPCOM000052739D
Original Publication Date: 1981-Jul-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 3 page(s) / 75K

Publishing Venue

IBM

Related People

Brandon, FY: AUTHOR [+4]

Abstract

Described below is a design for an ink jet drop generator which employs a piezoelectrically driven buckling diaphragm (unimorph crystal) which will enable the drop generator to produce a stream of satellite-free drops over a wide range of frequencies, temperature, and stream velocities.

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Unimorph Drop Generator for an Ink Jet Printer

Described below is a design for an ink jet drop generator which employs a piezoelectrically driven buckling diaphragm (unimorph crystal) which will enable the drop generator to produce a stream of satellite-free drops over a wide range of frequencies, temperature, and stream velocities.

Turning now to the drawing, disclosed therein is a drop generator 10 which utilizes a buckling diaphragm type of transducer. The buckling diaphragm transducer is called a unimorph crystal, and it consists of a stainless steel disk 11 which is bonded to a piezoelectric crystal 12. When voltage is applied to the crystal through a finger leaf spring type of electrical contact, as through the voltage input pin 13, the crystal 12 tends to expand along its diameter while the stainless steel disk 11 does not expand and resists the motion of the crystal. The buckling of the stainless steel disk results in motion in the ink cavity 14 which is in the crystal housing 15, producing a pressure pulse that breaks up the ink stream emanating from the nozzle 16 and orifice 17 into synchronous ink drops (not shown).

To reduce the head compliance for faster valving and more efficient drop breakup, the crystal is mounted so that it has a fixed or clamped edge condition. To achieve this condition, the crystal 0-ring 18 that seals the electrical cavity 13a from the ink cavity 14 must be compressed by the crystal diaphragm to the position where the crystal is being pinched by the two clamping surfaces 10a and 30a rather than resting on the O-ring. If the crystal is supported by the O-ring, the compliance would be too great, head variability too high, and there would be excessive amounts of trapped air in the drop generator.

As the pressure pulse travels towards the orifice 17 (glass), it proceeds through a porous wire mesh filter 20. By mounting the filter 20 solidly against the crystal housing, the pulse is permitted to pass through it without any deterioration or clamping. This woven mesh screen serves as a final filter in close proximity to the orifice 17. It removes the possibility of a few particles upstrea...