Tab circuit for ink jet printer cartridges

Details Tab circuit for ink jet printer cartridges Tab circuit for ink jet printer cartridges

2001-06-08

2003-09-16

Nguyen, Thinh (Department: 2853)

Incremental printing of symbolic information

Ink jet

Ejector mechanism

C347S059000, C029S840000, C029S890100

Reexamination Certificate

active

06619786

ABSTRACT:

TECHNICAL FIELD
The present invention relates generally to ink jet printers and is particularly directed to a TAB circuit of the type which carries electrical signals to an array of nozzles on a heater chip. The invention is specifically disclosed as a TAB circuit that eliminates bent or broken electrical circuit traces before being bonded to the heater chip, while also providing a window for the nozzle plate.
BACKGROUND OF THE INVENTION
TAB (Tape Automated Bonding) circuit technology has been used as the primary interconnect device between the heater chip of ink jet printers and the printer main body for many years. Conventional TAB circuits are comprised of a substrate material, usually polyimide, with some form of metallization on the substrate that forms electrical circuits. There are many patents that disclose the use of TAB circuits with ink jet printers, and most of these patents are owned by Hewlett-Packard Company of Palo Alto, Calif.
One example patent owed by Hewlett-Packard is U.S. Pat. No. 5,300,959, by McClelland. McClelland discloses a nozzle member for an ink jet printer cartridge that uses a flexible polymer tape (i.e., the TAB circuit) and affixes that tape to a substrate that contains the heating elements that create the droplets that jet forth from the nozzles. Electrical conductors that provide pathways for electrical signals to the substrate are located on the flexible polymer tape and, through an opening (or “via”), make a connection to the substrate “electrodes.” The vias are on the back side of the tape and face the conductive portions (i.e., electrodes) of the substrate.
McClelland's
FIG. 8
illustrates a partial cross-section of portions of the TAB circuit where it interfaces to the substrate.
FIG. 1
herein discloses a cross-section of a similar area of the TAB circuit interface to the substrate, but from a different angle. In
FIG. 1
herein, the TAB circuit is generally designated by the reference numeral
10
. The polyimide layer is designated by the reference numeral
12
, and is made of a material manufactured by DuPont that is also known as KAPTON®. A metal pathway or “trace” is provided from the left-hand side of
FIG. 1
at the reference numeral
14
. A similar electrical pathway or trace arrives from the right-hand side of
FIG. 1
at the reference numeral
16
. On the opposite side of the metal traces
14
and
16
is another layer of material at
18
. This layer of material
18
is either a covercoat material, or another layer of the polyimide or KAPTON material, and which insulates and covers the metal traces
14
and
16
in the direction that faces the substrate.
The substrate itself is designated by reference numeral
20
on
FIG. 1
, and includes the resistive heating elements and “electrodes” that make up what is commonly known as a “heater chip.” Two of the electrical pathways or electrodes are at the reference numerals
22
and
24
, and two of the resistive heating elements are at the reference numerals
26
and
28
. For example, the electrical signal that arrives at the electrode
22
could travel through a metal trace or pathway (not shown on
FIG. 1
) to connect to the heating resistor
26
, and when energized by a sufficient electrical power level, the heating resistor
26
will cause a droplet of ink to be spurted out through a nozzle opening at
34
in the TAB circuit
10
. Continuing this example, the electrode
24
could be connected using metal pathways or traces to the other heating resistive element on
FIG. 1
at
28
. When a sufficiently powerful electrical signal arrives at the heating resistor
28
, this will cause a droplet of ink to be spurted out through a nozzle opening
36
in the TAB circuit
10
.
The electrical connection between the metal trace
14
and the “electrode”
22
is created by a via or opening
30
in the covercoat layer
18
of the TAB circuit
10
. This via must be filled with some type of electrically conductive substance, which could be a conductively filled polymer. Or perhaps a reflow soldering method could be used, or even an ultrasonic welding procedure. In a similar manner, an electrical connection can be made between the trace
16
and the “electrode”
24
through the via
32
in the covercoat layer
18
of the TAB circuit
10
.
In the McClelland patent as illustrated in
FIG. 1
herein, there is no separate nozzle plate (or “orifice plate”) that forms the nozzle openings of most conventional ink jet cartridges. Instead, the TAB circuit
10
itself covers the entire nozzle area, including the middle area
38
between the nozzles
34
and
36
.
For example, U.S. Pat. No. 5,278,584 (by Keefe) discloses an ink jet printhead that has improved ink flow paths between the ink reservoir and vaporization chambers.
FIGS. 3 and 4
of Keefe illustrate the structure of the electrically conductive leads that are attached to the substrate. These conductive leads or traces are initially unsupported before being bonded to electrodes on the substrate. One advantage of the Keefe design is that the electrical traces that bring signals to the electrodes on the heater chip can all be temporarily run to a shorting bar (not shown) that can provide a single common electrode for an electroplating process for all of the circuit pathways of the TAB circuit itself. The McClelland design may not lend itself well for creating such a shorting bar. In Keefe, the shorting bar can be removed along with a portion of the polyimide material that creates a “chip window” in the nozzle area, and by which a nozzle plate can be installed through that chip window in the TAB circuit.
Conventional ink jet cartridges manufactured by Lexmark International, Inc. of Lexington, Ky. use a similar design to that disclosed in Keefe. One example of such similarity is the fact that the metal traces which carry electrical signals to the heater chip are initially unsupported at their terminal ends before a bonding procedure can be performed between the TAB circuit and the heater chip. Moreover, a “chip window” in the TAB circuit is created for installation of a nozzle plate, and also for the removal of the temporary shorting bar that provides an easy-to-access point used during the electroplating process of the metal traces of the TAB circuit itself. These unsupported circuit traces (also known as unsupported lead beams) extend into the chip window opening in the polyimide of the TAB circuit, and are later thermosonically bonded to metal contact pads on the heater chip. This chip window is formed by creating an internal edge through the polyimide that defines a closed perimeter, thereby forming a boundary (i.e., the internal edge).
FIG. 2
herein illustrates a portion of a TAB circuit used in a conventional Lexmark ink jet cartridge in the nozzle area. The polyimide material is generally designated by the reference numeral
50
, and is cut or otherwise etched along an edge at
52
that creates an opening or chip window
74
. This edge
52
will also be referred to herein as a “PI edge.” As part of the artwork that makes up this TAB circuit, a relatively large plus sign (“+”) is provided at
54
to aid in registration when mating the TAB circuit to the heater chip.
On
FIG. 2
, four different metalized circuit pathways or traces are illustrated at
60
,
61
,
62
, and
63
. These metal traces
60
-
63
each have an end point, designated respectively at the reference numerals
65
,
66
,
67
, and
68
. As can be easily seen on
FIG. 2
, these traces at their end points
65
-
68
terminate along a different line or plane than the PI edge
52
. As also can easily be seen in
FIG. 2
, these traces
60
-
63
are initially unsupported, as they extend past the PI edge
52
into open space.
Also as part of the TAB circuit on
FIG. 2
is a covercoat layer that is not visible in the figure, since it is on the opposite side of the TAB circuit. However, the edge of this covercoat layer is indicated by a hidden line at the reference numeral
70
on FIG.
2
. This covercoat material extends over the metal traces, which affects the shape of t

Affiliated with

Also associated with

Rating

Tab circuit for ink jet printer cartridges does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Tab circuit for ink jet printer cartridges, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tab circuit for ink jet printer cartridges will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3006594