Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-10-23
2003-11-25
Stephens, Juanita (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S043000, C347S065000
Reexamination Certificate
active
06652068
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The present invention relates to the field of ink jet printheads and associated ink delivering method, and more particularly, to a high-density ink jet printhead having a two-directional central ink flow channel and a one-directional periphery ink flow channel.
2. Description of the Related Art
Please refer to FIG.
1
.
FIG. 1
is a cross-sectional diagram of a prior art printhead
10
. Structures similar to the printhead
10
are disclosed in U.S. Pat. Nos. 4,680,859 and 4,683,481 of Samuel A. Johnson and assigned to Hewlett-Packard Company. The printhead
10
comprises a central ink feed slot
12
formed at a center portion of a substrate
14
. The ink feed slot
12
may be formed by sand blasting, laser cutting, or etching techniques. Heater resistors
16
are provided on both sides of the ink feed slot
12
for generating bubbles during an ink jet printing operation. An orifice plate
18
with a plurality of nozzles
22
formed therein is positioned on the substrate
14
and each of the nozzles
22
is positioned corresponding to one heater resistor
16
. During an ink jet printing operation, ink will flow through the central ink feed slot
12
to chambers
24
between the orifice plate
18
and the substrate
14
. The heater resistors
16
thereafter heat the ink flow into the chambers
24
to generate bubbles for pressurizing the ink, thereby forming an ink droplet
26
.
Please refer to FIG.
2
.
FIG. 2
is a cross-sectional diagram of a prior art printhead
30
. Similar structure is disclosed in U.S. Pat. No. 5,278,584 of Brian J. Keefe et al. and assigned to Hewlett-Packard Company. As shown in
FIG. 2
, the printhead
30
comprises a central ink slot
32
formed between a printhead cartridge
31
and a substrate
33
. channels
34
are formed between the end of the central slot
32
and vaporization chambers
36
. Each of the vaporization chambers
36
is provide with a thin film resistor
38
for generating a bubble. During an ink jet printing operation, ink from an ink reservoir (not shown) flows through the central slot
32
and split channels
34
to the vaporization chambers
36
. When the thin film resistors
38
are energized, the ink within the vaporization chambers
36
is ejected, as illustrated by the emitted drops of ink
42
.
Please refer to FIG.
3
.
FIG. 3
is another prior art printhead
50
disclosed in U.S. Pat. No. 6,010,208 of James Harold Powers et al. and assigned to Lexmark International Inc. Two rows of nozzles
54
are located one each side of a manifold
52
of the printhead
50
. Ink flows through the central manifold
52
laterally to the chambers
56
corresponding to the nozzles
54
.
Please refer to FIG.
4
and FIG.
5
.
FIG. 4
is a schematic diagram showing a prior art nozzle array of a color printhead
60
.
FIG. 5
is a schematic, cross-sectional view of an ink cartridge
70
having a printhead
60
of
FIG. 4
mounted thereon. The ink cartridge
70
comprises three ink reservoirs
72
for storing ink of different colors such as yellow, magenta, and cyan. The printhead
60
includes a substrate with three ink slots
62
and a plurality of nozzles
64
arranged in six columns on an orifice plate
61
. Each of the six columns of nozzles
64
is located on a side of the three ink slots
62
which are connected with associated ink reservoirs
72
. Likewise, ink from the ink reservoirs
72
flows through the ink slots to the chambers and then splits into two flows in opposite directions. The heater resistors
66
then create ink bubbles to form drops of ink out of the nozzles
64
.
FIG. 6
is nozzle array of another prior art color printhead
80
. Similarly, printhead
80
comprises six rows of nozzles
64
and three ink slots
62
(indicated by a dashed line). The difference between the printhead
60
and printhead
80
is the arrangement of the ink slots
62
.
From above, ink from an ink reservoir is delivered either through a central ink feed slot or edge feed path (through an edge of a substrate). Unfortunately, the nozzles must be located near the ink slot, thus limiting the nozzle number of a printhead and resolution.
SUMMARY OF INVENTION
Accordingly, the primary objective of the present invention is to provide a printhead capable of delivering colors of ink simultaneously from a central path and an edge path.
Another objective of this invention is to provide an ink delivery method for increasing nozzle number in a unit area. Four or more columns of nozzles may be packed into a printhead having a smaller printhead surface, thereby improving its resolution.
Still another objective of this invention is to provide a printhead having a smaller size that is capable of printing three or more colors of ink.
Briefly, the printhead has a substrate, a nozzle layer, and a plurality of bubble generators. A plurality of first chambers and a plurality of second chambers are formed between the nozzle layer and the top of the substrate. A central ink flow channel and a periphery ink flow channel for delivering ink to the chambers are formed in the substrate. The characteristic of the present invention is that positioning the central ink flow channel and the periphery ink flow channel together on the substrate so that the amount of the nozzles per unit area of the printhead is increased.
REFERENCES:
patent: 5025271 (1991-06-01), Baker et al.
patent: 6267468 (2001-07-01), Torgerson et al.
Chen Chih-Ching
Hsu Tsung-Ping
BenQ Corporation
Hsu Winston
Stephens Juanita
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