Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-10-29
2002-09-03
Nguyen, Lamson D. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S063000
Reexamination Certificate
active
06443557
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to a chip carrier having a taught and planar nozzle plate with a nozzle having a true bore formed therein. More specifically, the present invention relates to a chip carrier having a taught and planar nozzle plate with a nozzle that has a nozzle camber angle that is aligned with a firing axis of a thermal ink jet resistor and a nozzle axis of the nozzle so that fluid injected into the nozzle exits in a direction along the nozzle axis.
Articles and publications set forth herein are presented for the information contained therein: none of the information is admitted to be statutory “prior art” and we reserve the right to establish prior inventorship with respect to any such information.
Ink jet drop directionality can be improved by providing a nozzle plate having a nozzle with a true bore. A true bore is simply a nozzle in the nozzle plate that has sidewall surfaces that are uniform and symmetric about an axis of the nozzle. By way of analogy, an example of a true bore is the barrel of a cannon. The cannon has barrel sidewalls that are symmetric with respect to a bore axis of the canon. Thus, a projectile propelled thru the barrel exits the barrel with a trajectory that is along the bore axis. On the other hand, if the barrel has sidewalls that are not symmetric with respect to the bore axis then the barrel will not have a true bore (i.e. a crooked barrel) and the projectile will exit the barrel with a trajectory that is not along the bore axis. Consequently, the projectile will not strike its desired impact point. Therefore, lack of a true bore results in inaccuracies in the trajectory of the projectile.
Similarly, for a thermal ink jet printhead, an ink drop ejected from a firing chamber of the printhead and into a nozzle that does not have a true bore results in the ink drop exiting the nozzle with a trajectory that is not along the nozzle axis. As a result, the ink drop trajectory will deviate from a desired impact point on a print media such as a sheet of paper positioned opposite the nozzle.
In a typical thermal ink jet printhead, a semiconductor substrate is bonded to an orifice plate (a nozzle plate) using a barrier layer. A firing chamber is formed by the substrate and the barrier layer. A firing element such as a thermal ink jet resistor is disposed in the firing chamber and a firing axis of the firing element is aligned with a nozzle axis of a nozzle formed in the nozzle plate. The barrier layer seals the firing chamber to the nozzle plate so that the firing chamber is in fluid communication with the nozzle. A fluid channel communicates ink from an ink reservoir to the firing chamber. The substrate includes a signal line that electrically communicates a signal from a control unit (which may be connected to a source of printing data) to the firing element. A signal communicated to the firing element causes ink disposed on the element to be heated and subsequently ejected from the firing chamber and into the nozzle. The ink drop exits the nozzle with a trajectory that is determined by the symmetry of the nozzle. If the nozzle has a true bore, then the trajectory of the ink drop is substantially along an axis of the nozzle. Conversely, if the nozzle does not have a true bore then the trajectory of the ink drop deviates from the nozzle axis. By way of example, a general discussion of thermal ink jet printheads, nozzle plates, and thermal ink jet printhead construction can be found in the Hewlett-Packard Journal, Volume 39, No. 5, October 1998, Volume 39, No. 4, August 1998, and Volume 36, No. 5, May 1985.
Prior attempts to create a nozzle plate with a true bore nozzle have been frustrated by deformities in the nozzle plate. Typically, the nozzle plate is a thin film of flexible material such as a polyimide film, for example. The nozzle plate has opposed input and output surfaces thru which an orifice (a nozzle) is formed. The nozzle plate is then bonded to the substrate in a process called staking where the barrier layer is applied to the substrate and then heat and pressure are applied to attach the input surface of the nozzle plate to the barrier layer. The completed assembly is then baked at a high temperature to cure the barrier layer.
The deformities in the nozzle plate aries due to compressive buckling of the nozzle plate caused by the staking and baking process. Resulting is dimpling of the nozzle plate. The dimples in the nozzle plate resemble the peaks and troughs of ocean waves and can be sinusoidal in appearance. Therefore, the input and output surfaces of the nozzle plate deviate from planarity such that a nozzle formed in the nozzle plate will not have sidewall surfaces that are symmetric about the nozzle axis.
Moreover, the nozzle has openings on the input and output surfaces. A center point of symmetry on an input side of the nozzle is not coaxially aligned with a center point of symmetry on an output side of the nozzle. Resulting is misalignment between the input and output sides of the nozzle with respect to the nozzle axis. Because of the misalignment, sidewall surfaces of the nozzle are not symmetric with the nozzle axis, therefore, the nozzle does not have a true bore.
Referring to
FIG. 1
, there is illustrated a dimpled nozzle plate
101
having an input surface
103
disposed opposite an output surface
105
. The opposed surfaces have a generally sinusoidal contour; however, the nozzle plate can have other surface deformations that can result in a nozzle that does not have a true bore. A nozzle
107
is formed in the nozzle plate
101
by sidewall surfaces
109
that extend between the input surface
103
and the output surface
105
. Those skilled in the ink jet printer art commonly refer to the nozzle plate
101
as an orifice plate and the nozzle
107
as an orifice; however the term nozzle plate and nozzle will be used hereinafter.
A center point of symmetry
111
on an input side
113
(the side from which ink or some other fluid is injected into the nozzle) of the nozzle
107
is not coaxially aligned with a center point of symmetry
115
on an output side
117
of the nozzle
107
. A nozzle axis
119
is referenced to the center point of symmetry
111
on the input side
113
. Deviation from coaxial alignment between the center points of symmetry is measured in angular degrees by a nozzle camber angle (NCA)
123
. The NCA
123
is measured between the nozzle axis
119
and a camber line
121
extending thru the center points of symmetry
111
and
115
respectively. An ink drop or other fluid (not shown) entering the input side
113
of the nozzle
107
will exit the output side
117
with a trajectory that substantially matches the NCA
123
(i.e. the fluid trajectory is along the camber line
121
). Because of the dimple in the nozzle plate
101
, the sidewall surfaces
109
are not symmetric with respect to the nozzle axis
119
as will be discussed below.
Consequently, the ink drop, for example, will not strike a desired impact point on a print media.
FIG. 2
is an illustration of the effect the dimpled nozzle plate
101
of
FIG. 1
has on ink drop directionality. A print surface
133
of a print media
131
is shown with a desired impact point X and an actual impact point X′ displaced a lateral distance from the desired impact point X. The print media
131
can be a sheet of paper, for example. As can be seen in
FIG. 2
the actual impact point X′ coincides with the camber line
121
and is caused by the ink drop (not shown) having a trajectory that substantially matches the NCA
123
.
Additionally, the sidewall surfaces
109
of the nozzle
107
are not symmetric about the nozzle axis
119
due to the dimpling of the nozzle plate. Lack of symmetry between the nozzle axis
119
and the sidewall surfaces
109
is shown by unequal length radius lines d
1
and d
1
′, d
2
and d
2
′, and d
3
and d
3
′ that extend between the nozzle axis
119
and the sidewall surfaces
109
. Essentially, the nozzle
107
does not have a true bore due to lac
Field Marshall
I-Tsung Pan Alfred
Denny III Trueman H.
Nguyen Lamson D.
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