Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
1999-03-26
2001-08-07
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06270212
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet printer and more particularly to a print head for an ink jet printer including an ink passage whose wall is treated to obviate defective ink ejection.
It is a common practice with an ink jet printer to provide its ink passage with a hydrophilic wall for promoting the flow of ink and bubbles contained in the ink. Japanese Patent Laid-Open Publication No. 7-276629, for example, proposes to implement hydrophilicity by causing ozone with a preselected concentration to flow through the ink passage. Japanese Patent Laid-Open Publication No. 7-290714 teaches that an aqueous solution of an organic emulsion is circulated through the ink passage and then dried.
The above hydrophilicity of the wall of the ink passage is directed toward high wettability of the ink passage, i.e., smooth flow of the ink and bubbles contained therein. This kind of scheme allows a minimum of bubbles to remain in the ink passage and obstruct ink ejection when the ink passage is filled with the ink.
However, after the ink passage has been filled with the ink, a small amount of bubbles sometimes intermittently flow from, e.g., a cartridge upstream of the ink passage into the passage while the printer is in operation. Such bubbles would reach nozzles and render ink ejection from the nozzles defective. Moreover, should the bubbles gather on a filter and form a film thereon, they would increase resistance to the flow of the ink and obstruct ink feed into the head, also resulting in defective ink ejection.
Technologies relating to the present invention are also disclosed in, e.g., Japanese Patent Laid-Open Publication Nos. 4-173345, 5-345419, and 6-40040.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a print head for an ink jet printer including an ink passage whose wall is treated to obviate defective ink ejection for thereby enhancing printing quality and reliability.
In accordance with the present invention, a print head for an ink jet printer includes a plurality of nozzles for ejecting ink, an ink passage fluidly communicated to the nozzles, and a filter disposed in the ink passage. The ink passage has a hydrophobic wall upstream of the filter and a hydrophilic wall downstream of the filter. If desired, the ink passage may have a part upstream of the filter formed of a hydrophobic resin and a part downstream of the filter formed of a hydrophilic resin.
REFERENCES:
patent: 4853716 (1989-08-01), Oda
patent: 4890126 (1989-12-01), Hotomi
patent: 5353094 (1994-10-01), Kagayama
patent: 5558969 (1996-09-01), Uyttendaele et al.
patent: 5616447 (1997-04-01), Arioka
patent: 6090749 (2000-07-01), Kowalski
patent: 0645244 (1995-03-01), None
patent: 0869006 (1998-10-01), None
patent: 0887190 (1998-12-01), None
patent: 4-173345 (1992-06-01), None
patent: 5-345419 (1993-12-01), None
patent: 6-40040 (1994-02-01), None
patent: 7290714 (1995-10-01), None
patent: 7276629 (1995-11-01), None
European Search Report (in English) completed Dec. 1, 1999 and issued Dec. 9, 1999 in a related application.
Patent Abstracts of Japan, vol. 14, No. 563 (M-1058), Dec. 14, 1990 (1990-12-14) & JP 02 239939 A (NEC Corp), Sep. 21, 1990 (1990-09-21) *abstract*.
Patent Abstracts of Japan, vol. 1995, No. 3, Apr. 28, 1995 (1995-04-28) & JP 06 340071 A (Sharp Corp), Dec. 13, 1994 (1994-12-13) *abstract*.
Kusumi Tatsuya
Tanaka Koichi
Le N.
NEC Corporation
Nghiem Michael
Ostrolenk Faber Gerb & Soffen, LLP
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