Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-04-06
2001-01-30
Nguyen, Thinh (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C068S070000
Reexamination Certificate
active
06179408
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to impulse or drop-on demand ink jet printers employing an array of ink jets which are capable of printing a substantial field of droplets on demand.
U.S. Pat. No. 4,714,934 discloses an ink jet apparatus of the type shown in
FIGS. 1 through 3
. The apparatus includes a print head
10
having a reservoir
12
and an imaging head of
14
. The print head
10
is juxtaposed to a target
16
which is advanced by means of a transport system, including rollers
18
and
20
, in an incremental fashion. As shown in
FIG. 1
, print head
10
includes an orifice plate
22
, including orifices
24
. In
FIG. 1
, the orifices are shown further apart from each other than they are in practice for purposes of illustration.
The orifices
24
actually comprise a plurality of sets of orifices which are more fully described with reference to
FIGS. 2 and 3
. The sets of orifices
24
are vertically displaced as a result of the inclination of the print head
10
with respect to the scanning direction depicted by arrow
26
. The orifices
24
are arranged in groups of three (3) and inclined on the orifice plate
22
so as to be substantially vertical when the print head
10
is inclined with respect to the scanning direction
26
as shown in FIG.
1
. The hash marks
28
and the orifice plate actually show this angle of inclination. The angle of the orifices
24
in each group with respect to the vertical as shown in
FIG. 2
is chosen such that when the orifice plate
22
is inclined as shown in
FIG. 1
, sets of orifices
24
will be vertical. As scanning in the direction depicted by the arrow
26
proceeds, there is no overlap of any droplets projected from the orifices so as to permit the apparatus as shown in
FIGS. 1 through 3
to create a vertical bar when the droplets are ejected sequentially in the proper timed relationship. Of course, the droplets can also produce an alphanumeric character by ejecting appropriate droplets on demand.
By changing the angle of inclination of the hash marks
28
, it is possible to change the angle of inclination of the print head
14
. However, if the angle of inclination is increased beyond a certain limit, it becomes impossible to print a continuous bar since the orifices cannot be spaced sufficiently close together to provide full coverage of the field. In addition, the chambers associated with those orifices become starved for ink when operated at a sufficiently high frequency. Moreover, it has not been possible to increase the number of chambers since cross-talk and limited real estate do not allow transducers to be coupled to the chambers.
As also shown in U.S. Pat. No. 4,714,934, the individual ink jets include feet which are coupled to the ink jet chambers. These feet
46
are secured to a foot plate by a resilient rubber-like material, such as silicone. As a consequence, ink within the ink jet chambers is exposed to a variety of materials including the foot, the silicone and the materials from which the remainder of the ink jet including the chamber and the orifices are made. This in turn produces compatibility problems which effectively limit the type of ink which may be employed in an ink jet apparatus.
SUMMARY OF THE INVENTION
In accordance with one important aspect of the invention, an ink jet apparatus is provided whereby the spacing between a plurality of impulse ink jets in an array is substantially reduced thereby increasing the ability to print high quality images with an in-line array of orifices while minimizing cross-talk.
In accordance with this object of the invention, an ink jet apparatus comprises an array of chambers, each of the chambers being terminated in at least one orifice such that the linear array of orifices is formed. Each of the chambers includes an actuation location laterally displaced from the linear orifice array. A plurality of elongated transducers is juxtaposed to the actuation locations respectively such that the transducers have an axis of elongation extending substantially parallel with the ejection axis of each orifice and laterally displaced with respect to the linear orifice array.
In accordance with one important aspect of the invention, the actuation locations of adjacent chambers in the array of ink jet devices are mutually laterally displaced.
In accordance with another important aspect of the invention, the axis of chambers are inclined at an acute angle with respect to the ejection axis of the chambers.
In accordance with another important aspect of the invention, the axes of the chambers are elbowed to include a first segment substantially parallel to the ejection axis and a second segment substantially perpendicular to the ejection axis.
In accordance with still another important aspect of the invention, the axes of elongation of adjacent transducers are parallel but laterally displaced with respect to the axis of ejection from each of the orifices.
In accordance with yet another important aspect of the invention, each of the chambers may include one or more orifices.
It is another object of this invention to provide an impulse ink jet apparatus which has a high degree of compatibility with various inks. In accordance with this object of the invention, the ink jet apparatus includes an ink jet chamber, a transducer coupled to the chamber and a diaphragm separating the transducer from the chamber. In the preferred embodiment of the invention, the chamber and the diaphragm comprise a relatively inert material such as, for example, stainless steel.
The transducer is bonded to the diaphragm by a suitable adhesive such as for example, a silicone adhesive. The transducer may also be encapsulated in a silicone material for acoustic damping.
Preferably, the chamber is formed by sandwiching a plurality of stainless steel plates together including the diaphragm. The plates may comprise an orifice plate, chamber plate, a restrictor plate providing a restricted opening for ink to enter the chamber, the diaphragm and a spacer plate separating the diaphragm from the restrictor plate such that movement of the diaphragm does not affect the size of the restricted opening to the ink jet chamber.
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patent: 4194210 (1980-03-01), Krause
patent: 4357614 (1982-11-01), Tamai
patent: 4379304 (1983-04-01), Heinzl et al.
patent: 4396924 (1983-08-01), Rosenstock
patent: 4439780 (1984-03-01), DeYoung et al.
patent: 4459601 (1984-07-01), Howkins
patent: 4646106 (1987-02-01), Howkins
patent: 4680595 (1987-07-01), Cruz-Uribe et al.
patent: 4714934 (1987-12-01), Rogers
patent: 4901093 (1990-02-01), Ruggiero et al.
patent: 5142296 (1992-08-01), Lopez et all.
patent: 5767873 (1998-06-01), Rogers et al.
patent: 0 443 628 (1991-08-01), None
patent: 56-93567 (1981-07-01), None
patent: 56-135078 (1981-10-01), None
patent: 57-188372 (1982-11-01), None
patent: 60-92865 (1985-05-01), None
“Ink Jet Head”, IBM Technical Disclosure Bulletin, New York, Mar. 1974, vol. 16(10).
Cartin Jeffrey G.
Mikalsen Arthur
Rogers Robert L.
Data Products Corporation
Nguyen Thinh
Woodcock Washburn Kurtz Mackiewicz & Norris LLP
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