Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
1997-09-11
2003-05-13
Vo, Anh T. N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06561635
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the field of digitally controlled ink transfer printing devices, and in particular to such devices comprising sensors for label materials contained in inks to be used therewith.
BACKGROUND OF THE INVENTION
Ink jet printing has become recognized as a prominent contender in the digitally controlled, electronic printing arena because, e.g., of its non-impact, low-noise characteristics, its use of plain paper and its avoidance of toner transfers and fixing. Ink jet printing mechanisms can be categorized as either continuous ink jet or drop-on-demand ink jet. U.S. Pat. No. 3,946,398, which issued to Kyser et al. in 1970, discloses a drop-on-demand ink jet printer which applies a high voltage to a piezoelectric crystal, causing the crystal to bend, applying pressure on an ink reservoir and jetting drops on demand. Other types of piezoelectric drop-on-demand printers utilize piezoelectric crystals in push mode, shear mode, and squeeze mode. Piezoelectric drop-on-demand printers have achieved commercial success at image resolutions up to 720 dpi for home and office printers. However, piezoelectric printing mechanisms usually require complex high voltage drive circuitry and bulky piezoelectric crystal arrays, which are disadvantageous in regard to manufacturability and performance.
Great Britain Patent No. 2,007,162, which issued to Endo et al. in 1979, discloses an electrothermal drop-on-demand ink jet printer which applies a power pulse to an electrothermal heater which is in thermal contact with water based ink in a nozzle. A small quantity of ink rapidly evaporates, forming a bubble which cause drops of ink to be ejected from small apertures along the edge of the heater substrate. This technology is known as Bubblejet™ (trademark of Canon K.K. of Japan).
U.S. Pat. No. 4,490,728, which issued to Vaught et al. in 1982, discloses an electrothermal drop ejection system which also operates by bubble formation to eject drops in a direction normal to the plane of the heater substrate. As used herein, the term “thermal ink jet” is used to refer to both this system and system commonly known as Bubblejet™.
Thermal ink jet printing typically requires a heater energy of approximately 20 &mgr;J over a period of approximately 2 &mgr;sec to heat the ink to a temperature between 280° C. and 400° C. to cause rapid, homogeneous formation of a bubble. The rapid bubble formation provides the momentum for drop ejection. The collapse of the bubble causes a tremendous pressure pulse on the thin film heater materials due to the implosion of the bubble. The high temperatures needed necessitates the use of special inks, complicates the driver electronics, and precipitates deterioration of heater elements. The 10 Watt active power consumption of each heater is one of many factors preventing the manufacture of low cost high speed pagewidth printheads.
U.S. Pat. No. 4,275,290, which issued to Cielo et al., discloses a liquid ink printing system in which ink is supplied to a reservoir at a predetermined pressure and retained in orifices by surface tension until the surface tension is reduced by heat from an electrically energized resistive heater, which causes ink to issue from the orifice and to thereby contact a paper receiver. This system requires that the ink be designed so as to exhibit a change, preferably large, in surface tension with temperature. The paper receiver must also be in close proximity to the orifice in order to separate the drop from the orifice.
U.S. Pat. No. 4,166,277, which also issued to Cielo et al., discloses a related liquid ink printing system in which ink is supplied to a reservoir at a predetermined pressure and retained in orifices by surface tension. The surface tension is overcome by the electrostatic force produced by a voltage applied to one or more electrodes which lie in an array above the ink orifices, causing ink to be ejected from selected orifices and to contact a paper receiver. The extent of ejection is claimed to be very small in the above Cielo patents, as opposed to an “ink jet”, contact with the paper being the primary means of printing an ink drop. This system is disadvantageous, in that a plurality of high voltages must be controlled and communicated to the electrode array. Also, the electric fields between neighboring electrodes interfere with one another. Further, the fields required are larger than desired to prevent arcing, and the variable characteristics of the paper receiver such as thickness or dampness can cause the applied field to vary.
In U.S. Pat. No. 4,751,531, which issued to Saito, a heater is located below the meniscus of ink contained between two opposing walls. The heater causes, in conjunction with an electrostatic field applied by an electrode located near the heater, the ejection of an ink drop. There are a plurality of heater/electrode pairs, but there is no orifice array. The force on the ink causing drop ejection is produced by the electric field, but this force is alone insufficient to cause drop ejection. That is, the heat from the heater is also required to reduce either the viscous drag and/or the surface tension of the ink in the vicinity of the heater before the electric field force is sufficient to cause drop ejection. The use of an electrostatic force alone requires high voltages. This system is thus disadvantageous in that a plurality of high voltages must be controlled and communicated to the electrode array. Also the lack of an orifice array reduces the density and controllability of ejected drops.
Commonly assigned U.S. patent application Ser. No. 08/750,438 entitled A LIQUID INK PRINTING APPARATUS AND SYSTEM filed in the name of Kia Silverbrook on Dec. 3, 1996, discloses a liquid printing system that affords significant improvements toward overcoming the prior art problems associated with drop size and placement accuracy, attainable printing speeds, power usage, durability, thermal stresses, other printer performance characteristics, manufacturability, and characteristics of useful inks. Silverbrook provides a drop-on-demand printing mechanism wherein the means of selecting drops to be printed produces a difference in position between selected drops and drops which are not selected, but which is insufficient to cause the ink drops to overcome the ink surface tension and separate from the body of ink, and wherein an additional means is provided to cause separation of said selected drops from said body of ink. Several drop separation techniques are disclosed by Silverbrook, the following table entitled “Drop separation means” shows some of the possible methods for separating selected drops from the body of ink, and ensuring that the selected drops form dots on the printing medium. The drop separation means discriminates between selected drops and un-selected drops to ensure that un-selected drops do not form dots on the printing medium.
Drop separation means
Means
Advantage
Limitation
1. Electro-
Can print on rough
Requires high voltage
static
surfaces, simple
power supply
attraction
implementation
2. AC
Higher field strength is
Requires high voltage AC
electric
possible than electrosta-
power supply synchronized
field
tic, operating margins
to drop ejection phase.
can be increased, ink
Multiple drop phase
pressure reduced, and
operation is difficult
dust accumulation
is reduced
3. Proximity
Very small spot sizes can
Requires print medium to be
(printhead
be achieved. Very low
very close to printhead
in close
power dissipation. High
surface, unsuitable for rough
proximity to,
drop position accuracy
print media, usually requires
but not
transfer roller or belt
touching,
recording
medium)
4. Transfer
Very small spot sizes can
Not compact due to size of
Proximity
be achieved, very low
transfer roller or transfer
(printhead
power dissipation, high
belt.
is in close
accuracy, can print on
proximity
rough paper
to a transfer
roller or
belt
5. Proximity
Useful for hot melt inks
Requires print medium to be
with oscillating
using viscosity reduction
very close to printhead
ink
Eastman Kodak Company
Sales Milton S.
Vo Anh T. N.
LandOfFree
Ink delivery system and process for ink jet printing apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ink delivery system and process for ink jet printing apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ink delivery system and process for ink jet printing apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3086153