Droplet ejections by acoustic and electrostatic forces

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EP 0 586 187 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	14.06.1995 Bulletin 1995/24

(43)	Date of publication A2:
	09.03.1994 Bulletin 1994/10

(21)	Application number: 93306748.0

(22)	Date of filing: 25.08.1993

(51)	International Patent Classification (IPC)⁵: B41J 2/04

(84)	Designated Contracting States:
	DE FR GB

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Priority:

04.09.1992 US 940596

(71)	Applicant: XEROX CORPORATION
	Rochester New York 14644 (US)

(72)	Inventors:
	Quate, Calvin F. Stanford, California 9.4305 (US) Rawson, Eric G. Saratoga, California 95070 (US)

(74)	Representative: Goode, Ian Roy et al
	Rank Xerox Ltd Patent Department Parkway Marlow Buckinghamshire SL7 1YL Marlow Buckinghamshire SL7 1YL (GB)

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References cited: :

(54)	Droplet ejections by acoustic and electrostatic forces

(57) A technique for ejecting droplets using acoustic radiation and electrostatic attraction. Ejection proceeds by acoustically raising a mound (14) of ink (18) proximate an electrode (20) and then electrostatically attracting the mound by applying a voltage to the electrode. The electric field further accelerates the mound and, since the raised mound has a restricted volume, a Rayleigh instability necks off the mound, thereby creating a droplet (12). The droplet is ejected onto a recording medium (34) by the momentum imparted to the droplet by the acoustic energy and the electrostatic force. Beneficially, the applications of the acoustic energy and the electrode voltage are used to address the ejecting droplet ejector. Droplet ejectors in a column (or row) form a column (or row) of mounds, while an electrode voltage is applied to each of the electrodes of a row (or columns) of droplet ejectors. Only the droplet ejector associated with an acoustically raised a mound and with an energized electrode ejects a droplet.

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