Ink jet printheads - Patent 0465212

(19)

(11)

EP 0 465 212 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	25.11.1992 Bulletin 1992/48

(43)	Date of publication A2:
	08.01.1992 Bulletin 1992/02

(21)	Application number: 91305984.6

(22)	Date of filing: 02.07.1991

(51)	International Patent Classification (IPC)⁵: B41J 2/05, B41J 2/16, B41J 2/005

(84)	Designated Contracting States:
	DE FR GB

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Priority:

02.07.1990 US 547567

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

(72)	Inventors:
	Elhatem, Abdul M. Hawthorne, California 90250 (US) Buhler, Steven A. Redondo Beach, California (US) Mojaradi, Mohammed M. Los Angeles, California 90025 (US) Patel, Putul D. Diamond Bar, California 91765 (US) Mazdiyazni, Parviz P. Brea, California 92621 (US)

(74)	Representative: Weatherald, Keith Baynes et al
	Rank Xerox Ltd Patent Department Parkway Marlow Buckinghamshire SL7 1YL Marlow Buckinghamshire SL7 1YL (GB)

(56)

References cited: :

(54)	Ink jet printheads

(57) A thermal inkjet printhead is disclosed having improved reliability and thermal efficiency. The printhead includes heater resistors (14) and thin protective regions (46) positioned above the heating resistors for protecting the heating resistors from corrosion and cavitation damage from the ink. The heating resistors are positioned substantially within the geometric confines of the portion of the protective regions exposed to the ink. Positioned between the resistors and the underlying printhead structure are field oxide regions (60) that thermally insulate the heating resistors from the underlying printhead structure. Positioned between the resistors and the underlying printhead structure is a passivation layer consisting of a middle layer (62) of phosphorus glass, an underglaze (64) between the middle layer and the underlying printhead structure, and glass mesas (66) between the middle layer and the resistors. The underglaze helps prevent phosphorus from the middle layer from contaminating the underlying printhead structure. Similarly, the glass mesas prevent phosphorus from the middle layer from contaminating the resistors.

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