Information
-
Patent Grant
-
6315389
-
Patent Number
6,315,389
-
Date Filed
Thursday, April 13, 200024 years ago
-
Date Issued
Tuesday, November 13, 200122 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 347 40
- 347 71
- 347 74
- 347 65
-
International Classifications
-
Abstract
An ink jet printhead having a plurality of columnar arrays of ink drop generators that have different center to center spacing along a reference axis. The ink jet printhead further includes ink feed slots that are each fluidically connected to only one columnar array of ink drop generators.
Description
BACKGROUND OF THE INVENTION
The subject invention generally relates to ink jet printing, and more particularly to a thin film ink jet printhead having ink drop generators of different print resolution.
The art of ink jet printing is relatively well developed. Commercial products such as computer printers, graphics plotters, and facsimile machines have been implemented with ink jet technology for producing printed media. The contributions of Hewlett-Packard Company to ink jet technology are described, for example, in various articles in the
Hewlett-Packard Journal,
Vol. 36, No. 5 (May 1985); Vol. 39, No. 5 (October 1988); Vol. 43, No. 4 (August 1992); Vol. 43, No. 6 (December 1992); and Vol. 45, No. 1 (February 1994); all incorporated herein by reference.
Generally, an ink jet image is formed pursuant to precise placement on a print medium of ink drops emitted by an ink drop generating device known as an ink jet printhead. Typically, an ink jet printhead is supported on a movable print carriage that traverses over the surface of the print medium and is controlled to eject drops of ink at appropriate times pursuant to command of a microcomputer or other controller, wherein the timing of the application of the ink drops is intended to correspond to a pattern of pixels of the image being printed.
A typical Hewlett-Packard ink jet printhead includes an array of precisely formed nozzles in an orifice plate that is attached to an ink barrier layer which in turn is attached to a thin film substructure that implements ink firing heater resistors and apparatus for enabling the resistors. The ink barrier layer defines ink channels including ink chambers disposed over associated ink firing resistors, and the nozzles in the orifice plate are aligned with associated ink chambers. Ink drop generator regions are formed by the ink chambers and portions of the thin film substructure and the orifice plate that are adjacent the ink chambers.
The thin film substructure is typically comprised of a substrate such as silicon on which are formed various thin film layers that form thin film ink firing resistors, apparatus for enabling the resistors, and also interconnections to bonding pads that are provided for external electrical connections to the printhead. The ink barrier layer is typically a polymer material that is laminated as a dry film to the thin film substructure, and is designed to be photodefinable and both UV and thermally curable. In an ink jet printhead of a slot feed design, ink is fed from one or more ink reservoirs to the various ink chambers through one or more ink feed slots formed in the substrate.
An example of the physical arrangement of the orifice plate, ink barrier layer, and thin film substructure is illustrated at page 44 of the
Hewlett-Packard Journal
of February 1994, cited above. Further examples of ink jet printheads are set forth in commonly assigned U.S. Pat. Nos. 4,719,477 and 5,317,346, both of which are incorporated herein by reference.
Considerations with thin film ink jet printheads include increased substrate size and/or substrate fragility as more ink drop generators and/or ink feed slots are employed. There is accordingly a need for an improved ink jet printhead that is compact and has a large number of ink drop generators.
SUMMARY OF THE INVENTION
The disclosed invention is directed to an ink jet printhead that includes a printhead substrate, a first plurality of ink drop generators formed in the substrate and having a first predetermined center to center spacing along a reference axis, and a second plurality of ink drop generators formed in the printhead substrate and having a second predetermined center to center spacing along the reference axis.
BRIEF DESCRIPTION OF THE DRAWINGS
The advantages and features of the disclosed invention will readily be appreciated by persons skilled in the art from the following detailed description when read in conjunction with the drawing wherein:
FIG. 1
is an unscaled schematic top plan illustration of the layout of an ink jet printhead that employs the invention.
FIG. 2
is a schematic, partially broken away perspective view of the ink jet printhead of FIG.
1
.
FIG. 3
is an unscaled schematic partial top plan illustration of the ink jet printhead of FIG.
1
.
FIG. 4
is an unscaled schematic partial top plan view of another ink jet printhead that employs the invention.
FIG. 5
is an unscaled schematic bottom plan view of the thin film substructure of the ink jet printhead of
FIG. 1
illustrating adhesive contact areas.
FIG. 6
is an unscaled schematic illustration of a print cartridge that includes a headland area to which the ink jet printhead of
FIG. 1
or
FIG. 3
can be attached.
FIG. 7
is an unscaled schematic perspective view of a printer in which the printhead of the invention can be employed.
DETAILED DESCRIPTION OF THE DISCLOSURE
In the following detailed description and in the several figures of the drawing, like elements are identified with like reference numerals.
Referring now to
FIGS. 1 and 2
, schematically illustrated therein is an unscaled schematic perspective view of an ink jet printhead in which the invention can be employed and which generally includes (a) a thin film substructure or die
11
comprising a substrate such as silicon and having various thin film layers formed thereon, (b) an ink barrier layer
12
disposed on the thin film substructure
11
, and (c) an orifice or nozzle plate
13
laminarly attached to the top of the ink barrier
12
.
The thin film substructure
11
is formed pursuant to conventional integrated circuit techniques, and includes thin film heater resistors
56
formed therein. The ink barrier layer
12
is formed of a dry film that is heat and pressure laminated to the thin film substructure
11
and photodefined to form therein ink chambers
19
and ink channels
29
which are disposed over resistor regions in which the heater resistors are formed. Gold bonding pads
74
engagable for external electrical connections are disposed at the ends of the thin film substructure
11
and are not covered by the ink barrier layer
12
. By way of illustrative example, the barrier layer material comprises an acrylate based photopolymer dry film such as the “Parad” brand photopolymer dry film obtainable from E. I. duPont de Nemours and Company of Wilmington, Del. Similar dry films include other duPont products such as the “Riston” brand dry film and dry films made by other chemical providers. The orifice plate
13
comprises, for example, a planar substrate comprised of a polymer material and in which the orifices are formed by laser ablation, for example as disclosed in commonly assigned U.S. Pat. No. 5,469,199, incorporated herein by reference. The orifice plate can also comprise a plated metal such as nickel.
As depicted in
FIG. 3
, the ink chambers
19
in the ink barrier layer
12
are more particularly disposed over respective ink firing resistors
56
, and each ink chamber
19
is defined by interconnected edges or walls of a chamber opening formed in the barrier layer
12
. The ink channels
29
are defined by further openings formed in the barrier layer
12
, and are integrally joined to respective ink firing chambers
19
.
FIGS. 1
,
2
and
3
illustrate by way of example a slot fed ink jet printhead wherein the ink channels open towards an edge formed by an ink feed slot in the thin film substructure, whereby the edge of the ink feed slot forms a feed edge.
The orifice plate
13
includes orifices or nozzles
21
disposed over respective ink chambers
19
, such that each ink firing resistor
56
, an associated ink chamber
19
, and an associated orifice
21
are aligned and form an ink drop generator
40
.
While the disclosed printhead has been described as having a barrier layer and a separate orifice plate, it should be appreciated that the invention can be implemented in printheads having an integral barrier/orifice structure that can be made using a single photopolymer layer that is exposed with a multiple exposure process and then developed.
The ink drop generators
40
are arranged in four columnar arrays or groups
61
,
62
,
63
,
64
that are spaced apart from each other transversely relative to a reference axis L. The heater resistors
56
of each ink drop generator group are generally aligned with the reference axis L and have a predetermined center to center spacing or nozzle pitch (P
1
or P
2
, as described further herein) along the reference axis L. Two ink drop generator groups
61
,
64
are respectively located adjacent opposite edges
51
,
52
of the thin film substructure
11
while two ink drop generator groups
62
,
63
are located in the middle portion of the thin film substructure, such that the two ink drop generator groups
62
,
63
are between and inboard of the ink drop generator groups
61
,
64
which are outboard groups. By way of illustrative example, the thin film substructure is rectangular and opposite edges
51
,
52
thereof are longitudinal edges of the length dimension while opposite edges
53
,
54
are of the width dimension which is less than the length dimension of the printhead. The longitudinal edges
51
,
52
can be parallel to the reference axis L. In use, the reference axis L can be aligned with what is generally referred to as the media advance axis.
While the ink drop generators
40
of each ink drop generator group are illustrated as being substantially collinear, it should be appreciated that some of the ink drop generators
40
of an ink drop generator group can be slightly off the center line of the column, for example to compensate for firing delays.
Insofar as each of the ink drop generators
40
includes a heater resistor
56
, the heater resistors are accordingly arranged in groups or arrays that correspond to the ink drop generators. For convenience, the heater resistor arrays or groups will be referred to by the same reference numbers
61
,
62
,
63
,
64
.
The ink drop generators
40
of the outboard group
61
that is adjacent the longitudinal edge
51
of the thin film substructure
11
have a center to center spacing (or nozzle pitch) P
1
along the reference axis, and the ink drop generators
40
of the outboard group
64
that is adjacent the longitudinal edge
52
also have the center to center spacing P
1
. The ink drop generators
40
of the inboard group
62
have a center to center spacing P
2
along the reference axis that is different than the center to center spacing P
1
, and the ink drop generators
40
of the inboard group
63
also have the center to center spacing P
2
. In other words, ink drop generators
40
of each of the outboard groups
61
,
64
are spaced closer or further to each other within the group along the reference axis L than the ink generators
40
of each of the inboard groups
62
,
63
.
By way of illustrative example, the center to center spacing P
2
is twice the center to center spacing P
1
, and the ink drop generators
40
of the inboard group
62
are staggered along the reference axis relative to the ink drop generators
40
of the inboard group
63
such that a combined center to center spacing PC of the ink drop generators of the inboard groups
62
,
63
is substantially equal to the center to center spacing P
1
. More generally, the center to center spacing P
2
of ink drop generators
40
of each of the inboard groups
62
,
63
can be selected such that the composite center to center spacing PC, along the reference axis L, of the combination of the inboard groups
62
,
63
is an integral multiple of the center to center or nozzle spacing P
1
of each of the outboard groups
61
,
64
.
The foregoing arrangement of ink drop generators can be implemented in an exclusively slot fed printhead, as shown in
FIGS. 1
,
2
and
3
, or an edge fed and slot fed printhead, as shown in FIG.
4
. More particularly, the inboard ink drop generator groups
62
,
63
receive ink from the same ink feed slot
72
and thus produce ink drops of the same color, while the outboard groups
61
,
64
receive ink from either different slots
71
,
73
or different outside edges
51
,
52
such that the outboard ink drop generator groups
61
,
64
can respectively produce ink drops of respectively different colors or the same color. By way of illustrative example, to the extent that, in the manufacture of the printhead, the placement and/or alignment of the ink drop generators
40
of the inboard groups
62
,
63
is not as precise as the placement and/or alignment of the ink drop generators of the outboard groups
61
,
64
, the ink drop generators
40
of the inboard groups
62
,
63
can be configured to produce drops of a color having a greater dot size threshold of visual acuity, such as yellow in a cyan, yellow, magenta color system. In this manner, since dot placement errors of yellow dot is less noticeable, yellow dots are produced by ink drop generators that tend to produce greater dot placement errors.
The thin film substructure
11
of the printhead of
FIGS. 1
,
2
and
3
more particularly includes ink feed slots
71
,
72
,
73
that are aligned with the reference axis L, and are spaced apart from each other transversely relative to a reference axis L. The ink feed slot
72
is located between the inboard ink drop generator groups
62
,
63
and feeds ink to those ink drop generator groups, while the ink feed slots
71
,
73
are respectively located inboard of the outboard ink drop generator group
61
and the outboard ink drop generator group
64
, and respectively provide ink only to the ink drop generators
40
of an adjacent outboard ink drop generator group. More particularly, the ink feed slot
71
is located between the outboard ink drop generator group
61
and the inboard ink drop generator group
62
, but is fluidically coupled only to the outboard ink drop generator group
61
that is adjacent the edge
51
of the thin film substructure. Similarly, the ink feed slot
73
is located between the outboard ink drop generator group
64
and the inboard ink drop generator group
63
, but is fluidically coupled only to the ink drop generator group
64
that is adjacent the edge
52
of the thin film substructure
11
. In other words, the ink feed slot
72
is a double-edge or double-side feeding ink slot, while each of the outboard ink feed slots
71
,
73
is a single-edge or single-side feeding ink slot.
The thin film substructure
11
further includes a first circuit region
81
disposed between a laterally outermost ink feed slot
71
and the inboard ink drop generator group
62
, and a second circuit region
82
disposed between the other laterally outermost ink feed slot
73
and the inboard ink drop generator group
63
. The first circuit region
81
is available for drive circuitry (e.g., drive transistors and/or interconnect lines) for the inboard ink drop generator group
62
, while the second circuit region
82
is available for drive circuitry for the in board ink drop generator group
63
.
Referring now to
FIG. 4
, the above described layout of the ink drop generators
40
can be implemented in an edge fed and slot fed printhead, wherein the ink channels
19
that lead into the outboard ink generator groups
61
,
64
open towards the longitudinal edges
51
,
52
of the thin film substrate
11
. Examples of edge fed printheads are disclosed in commonly assigned U.S. Pat. Nos. 5,604,519; 5,638,101; and 3,568,171, incorporated herein by reference. The inboard ink drop generator groups
62
,
63
receive ink from an ink feed slot
72
located between the inboard groups
62
,
63
.
The disclosed layout of ink drop generators of an ink jet printhead and the layout of ink feed slots of an ink jet printhead advantageously avoid thin film substrate fragility and provide for a strong compact thin film substructure in view of structure between the edges of the thin film substructure and the slots
71
,
73
, as well as structure between the slots
71
,
72
,
73
. Referring more particularly to
FIG. 5
, the layout of the thin film substructure
11
further provides for an optimal interface area
83
on the lower side of the thin film substructure
11
for attaching the printhead to a headland area
91
of a print cartridge body
90
(FIG.
6
). The interface area
83
more particularly is an area on the lower side of the thin film substructure
11
that can be contacted by an adhesive that is utilized to attach the printhead to a headland area
91
of a print cartridge body
90
. The interface area
83
more particularly comprises side by side elongated closed loops that respectively surround openings of the slots
71
,
72
,
73
on the lower surface of the thin film substructure
11
. The headland area
91
of the print cartridge
90
more particularly includes flanges
95
that surround ink slots
93
and match the interface pattern
83
on the lower side of the thin film substructure and are adhesively attached to the lower side of the thin film substructure. For example, an adhesive bead is formed on the flanges
95
of the headland are
91
and the printhead is then pressed onto the headland
91
with the interface pattern
83
in alignment with the flanges
95
of the headland. In this manner, the ink slots in cartridge body
90
, the adhesive, and the ink feed slots in the printhead effectively form respective conduits for transporting ink from reservoirs in the print cartridge body
90
to the ink channels of the ink jet printhead.
Referring now to
FIG. 7
, set forth therein is a schematic perspective view of an example of an ink jet printing device
110
in which the above described printheads can be employed. The ink jet printing device
110
of
FIG. 7
includes a chassis
122
surrounded by a housing or enclosure
124
, typically of a molded plastic material. The chassis
122
is formed for example of sheet metal and includes a vertical panel
122
a.
Sheets of print media are individually fed through a print zone
125
by an adaptive print media handling system
126
that includes a feed tray
128
for storing print media before printing. The print media may be any type of suitable printable sheet material such as paper, card-stock, transparencies, Mylar, and the like, but for convenience the illustrated embodiments described as using paper as the print medium. A series of conventional motor-driven rollers including a drive roller
129
driven by a stepper motor may be used to move print media from the feed tray
128
into the print zone
125
. After printing, the drive roller
129
drives the printed sheet onto a pair of retractable output drying wing members
130
which are shown extended to receive a printed sheet. The wing members
130
hold the newly printed sheet for a short time above any previously printed sheets still drying in an output tray
132
before pivotally retracting to the sides, as shown by curved arrows
133
, to drop the newly printed sheet into the output tray
132
. The print media handling system may include a series of adjustment mechanisms for accommodating different sizes of print media, including letter, legal, A-4, envelopes, etc., such as a sliding length adjustment arm
134
and an envelope feed slot
135
.
The printer of
FIG. 7
further includes a printer controller
136
, schematically illustrated as a microprocessor, disposed on a printed circuit board
139
supported on the rear side of the chassis vertical panel
122
a.
The printer controller
136
receives instructions from a host device such as a personal computer (not shown) and controls the operation of the printer including advance of print media through the print zone
125
, movement of a print carriage
140
, and application of signals to the ink drop generators
40
.
A print carriage slider rod
138
having a longitudinal axis parallel to a carriage scan axis is supported by the chassis
122
to sizeably support a print carriage
140
for reciprocating transnational movement or scanning along the carriage scan axis. The print carriage
140
supports first and second removable ink jet printhead cartridges
150
,
152
(each of which is sometimes called a “pen,” “print cartridge,” or “cartridge”). The print cartridges
150
,
152
include respective printheads
154
,
156
that respectively have generally downwardly facing nozzles for ejecting ink generally downwardly onto a portion of the print media that is in the print zone
125
. The print cartridges
150
,
152
are more particularly clamped in the print carriage
140
by a latch mechanism that includes clamping levers, latch members or lids
170
,
172
.
An illustrative example of a suitable print carriage is disclosed in commonly assigned U.S. application Ser. No. 08/757,009, filed Nov. 26, 1996, Harmon et al., incorporated herein by reference.
For reference, print media is advanced through the print zone
125
along a media axis which is parallel to the tangent to the portion of the print media that is beneath and traversed by the nozzles of the cartridges
150
,
152
. If the media axis and the carriage axis are located on the same plane, as shown in
FIG. 7
, they would be perpendicular to each other.
An anti-rotation mechanism on the back of the print carriage engages a horizontally disposed anti-pivot bar
185
that is formed integrally with the vertical panel
122
a
of the chassis
122
, for example, to prevent forward pivoting of the print carriage
140
about the slider rod
138
.
By way of illustrative example, the print cartridge
150
is a monochrome printing cartridge while the print cartridge
152
is a tri-color printing cartridge that employs a printhead in accordance with the teachings herein.
The print carriage
140
is driven along the slider rod
138
by an endless belt
158
which can be driven in a conventional manner, and a linear encoder strip
159
is utilized to detect position of the print carriage
140
along the carriage scan axis, for example in accordance with conventional techniques.
Although the foregoing has been a description and illustration of specific embodiments of the invention, various modifications and changes thereto can be made by persons skilled in the art without departing from the scope and spirit of the invention as defined by the following claims.
Claims
- 1. An ink jet printing apparatus comprising:a printhead substrate including a plurality of thin film layers and having a first edge and a second edge opposite said first edge; a first plurality of ink drop generators defined in said printhead substrate adjacent said first edge and having a first predetermined center to center spacing along a reference axis; a second plurality of ink drop generators defined in said printhead substrate adjacent said second edge and spaced laterally, relative to the reference axis, from said first plurality of ink drop generators, said second plurality of ink drop generators having said first predetermined center to center spacing; a third plurality of ink drop generators defined in said printhead substrate and having a second predetermined center to center spacing along said reference axis that is greater than said first predetermined center to center spacing; a fourth plurality of ink drop generators defined in said printhead substrate and spaced laterally, relative to said reference axis, from said third plurality of ink drop generators, said fourth plurality of ink drop generators having said second predetermined center to center spacing along said reference axis; and wherein said third plurality of ink drop generators and said fourth plurality of ink drop generators are located between said first plurality of ink drop generators and said second plurality of ink drop generators.
- 2. The ink jet printing apparatus of claim 1 further including an ink feed slot aligned with said reference axis, and wherein said third plurality of ink drop generators are on one side of said ink feed slot and wherein said fourth plurality of ink drop generators are on another side of said ink feed slot.
- 3. The ink jet printing apparatus of claim 1 wherein said fourth plurality of ink drop generators are staggered relative to said third plurality of ink drop generators along said reference axis such that said third plurality of ink drop generators and said fourth plurality of ink drop generators have a combined center to center spacing along said reference axis that is substantially equal to said first predetermined center to center spacing.
- 4. The ink jet printing apparatus of claim 1 wherein said third plurality of ink drop generators and said fourth plurality of ink drop generators produce yellow ink drops.
- 5. An ink jet printing apparatus comprising:a printhead structure formed of a substrate, a plurality of thin film layers, an ink barrier layer and a plurality of nozzles; a first plurality of ink drop generators defined in said printhead structure adjacent an edge of said printhead substrate and having a first predetermined center to center spacing along a reference axis; an ink feed slot in said substrate aligned with said reference axis; a second plurality of ink drop generators defined in said printhead structure adjacent one side of said ink feed slot and having a second predetermined center to center spacing along said reference axis that is greater than said first predetermined center to center spacing; a third plurality of ink drop generators defined in said printhead substrate adjacent another side of said ink feed slot that is opposite said one side and spaced laterally, relative to said reference axis, from said second plurality of ink drop generators, said third plurality of ink drop generators having said second predetermined center to center spacing along said reference axis; wherein said first plurality of ink drop generators is between said edge and said second plurality of ink drop generators; and wherein said second plurality of drop generators and said third plurality of drop generators produce yellow ink drops.
- 6. An ink jet printing apparatus comprising:a printhead structure formed of a substrate, a plurality of thin film layers, an ink barrier layer and a plurality of nozzles; a first plurality of ink drop generators defined in said printhead structure adjacent an edge of said printhead substrate and having a first predetermined center to center spacing along a reference axis; an ink feed slot in said substrate aligned with said reference axis; a second plurality of ink drop generators defined in said printhead structure on one side of said ink feed slot and having a second predetermined center to center spacing along said reference axis that is greater than said first predetermined center to center spacing; a third plurality of ink drop generators defined in said printhead substrate on another side of said ink feed slot that is opposite said one side and spaced laterally, relative to said reference axis, from said second plurality of ink drop generators, said third plurality of ink drop generators having said second predetermined center to center spacing along said reference axis; wherein said third plurality of ink drop generators are staggered relative to said second plurality of ink drop generators along said reference axis such that said second plurality of ink drop generators and said third plurality of ink drop generators have a combined center to center spacing along said reference axis that is substantially equal to said first predetermined center to center spacing; wherein said first plurality of ink drop generators is between said edge and said second plurality of ink drop generators; and wherein said second plurality of drop generators and said third plurality of drop generators produce yellow ink drops.
- 7. An ink jet printing apparatus comprising:a printhead structure formed of a substrate, a plurality of thin film layers, an ink barrier layer and a plurality of nozzles; a first plurality of ink drop generators defined in said printhead structure and having a first predetermined center to center spacing along a reference axis; an ink feed slot in said substrate aligned with said reference axis; a second plurality of ink drop generators defined in said printhead structure adjacent one side of said ink feed slot and having a second predetermined center to center spacing along said reference axis that is greater than said first predetermined center to center spacing; and a third plurality of ink drop generators defined in said printhead substrate adjacent another side of said ink feed slot that is opposite said one side and spaced laterally, relative to said reference axis, from said second plurality of ink drop generators, said third plurality of ink drop generators having said second predetermined center to center spacing along said reference axis.
- 8. The ink jet printing apparatus of claim 7 wherein said first plurality of ink drop generators is adjacent an edge of said printhead substrate so as to be between said edge and said second plurality of ink drop generators.
- 9. The ink jet printing apparatus of claim 7 wherein said third plurality of ink drop generators are staggered relative to said second plurality of ink drop generators along said reference axis such that said second plurality of ink drop generators and said third plurality of ink drop generators have a combined center to center spacing along said reference axis that is substantially equal to said first predetermined center to center spacing.
- 10. The ink jet printing apparatus of claim 7 wherein said first plurality of ink drop generators are adjacent an edge of said printhead substrate so as to be between said edge and said second plurality of ink drop generators.
- 11. The ink jet printing apparatus of claim 7 wherein said second plurality of ink drop generators and said third plurality of ink drop generators produce yellow ink drops.
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Date |
Kind |
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Hoisington et al. |
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|
5208605 |
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May 1993 |
|
5880756 |
Ishii et al. |
Mar 1999 |
|
5946012 |
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Number |
Date |
Country |
61-104856 |
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JP |