Wiper for inkjet printers

Details Wiper for inkjet printers Wiper for inkjet printers

2000-06-14

2002-10-08

Barlow, John (Department: 2853)

Incremental printing of symbolic information

Ink jet

Ejector mechanism

Reexamination Certificate

active

06460968

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates generally to inkjet printers, and particularly, to a method and structure for wiping the printhead.
Inkjet printers use pens that shoot drops of ink onto media such as paper sheets. Each pen has a printhead formed with very small nozzles through which the ink drops are fired. The printhead is mounted on a bi-directionally movable carriage, such carriage being configured to reciprocate back and forth across the paper as printing occurs. The structure and operation of such printheads and carriages are well known to those skilled in the art.
In order to keep printheads in proper printing condition, most inkjet printers use a mechanism at some point along the printhead's path to periodically service the printhead during normal use. Such mechanism generally includes a wiper that sweeps across the printhead to clear its printing surface of contaminants such as dried or drying ink.
A conventional wiper includes a chassis-mounted base and an elongate blade. The blade extends from the base to a tip that engages the printhead's printing surface when the printhead passes across it. The blade is typically planar and is of a size determined by the physical characteristics of the printer in which it is used. The blade's thickness is determined to produce a wiper that exerts a desired force on the printhead when the wiper is engaged with the printhead. Typically, the blade is made of flexible material.
FIGS. 1 and 2
illustrate a conventional wiper wiping a printhead. In
FIG. 1
, a cartridge
10
has an ink reservoir
12
and a printhead
14
. The printhead
14
has a metal or plastic orifice plate
16
with two parallel columns of offset nozzles
18
formed on the plate
16
. The orifice plate
16
is fixed to the surface of a semiconductor substrate (not shown).
FIG. 2
is taken along line A—A in
FIG. 1
to illustrate an elastomeric wiper
20
wiping the printhead
14
. As indicated, the wiper
20
is in the form of an elongate blade which includes a wiping region
22
. The wiper
20
, in particular the wiping region
22
, presses against the nozzle plate
16
of the associated print cartridge to wipe off ink drops. During the wiping, however, the edge
22
a
of the wiping region
22
scratches exit regions
24
of the nozzles
18
as illustrated. Such scratches cause damages to the nozzles such that the exist regions
24
of the nozzles
18
are deformed. These damages affect the size, trajectory, and speed of ink drop ejection during printing, and in turn affect the inkjet printhead's performance.
Accordingly, there is a need for a wiper that does not damages the nozzles' exist regions.
SUMMARY OF THE INVENTION
In a preferred embodiment, the invention provides a wiper that does not scratch exit regions of nozzles during wiping process.
In a preferred embodiment according to the invention, a wiper for inkjet printhead has a slightly recessed wiping region at a first end. The recessed wiping region is positioned approximately opposite to columns of nozzles of the printhead during wiping and indirectly contacts the nozzles. Thus, the wiper does not directly contact the nozzles.
According to a further aspect of the invention, the wiper also has a non-recessed wiping region at the first end and adjacent to the recessed wiping region. The non-recessed wiping region presses against the printhead to exert desired forces for wiping. Preferably, the non-recessed wiping region maintains a gap between the printhead and the recessed wiping region.


REFERENCES:
patent: 5610641 (1997-03-01), Ikado
patent: 5614930 (1997-03-01), Osborne et al.
patent: 5815176 (1998-09-01), Rotering
patent: 6155666 (2000-12-01), Sugimoto et al.
patent: 446885 (1991-09-01), None
patent: 0673772 (1995-09-01), None
patent: 403019847 (1991-01-01), None
patent: 403215043 (1991-09-01), None

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