Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-01-08
2001-02-06
Moses, Richard (Department: 2852)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S085000
Reexamination Certificate
active
06183069
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to ink jet printing devices and more particularly to thermal ink jet printheads having a patternable ink flow directing channel structure.
In one conventional thermal ink jet printhead, the printhead consists of two sections, a heater plate and a channel plate. Some geometrical features are formed in both plates in such a way that, when bonded together, they form the desired configuration for ink droplet ejection. For example, U.S. Pat. No. 4,774,530 discloses a printhead in which upper and lower silicon substrates are mated and bonded together with a thick film insulative layer sandwiched therebetween. One surface of the upper substrate or channel plate has a plurality of parallel grooves and a recess etched therein. When mated with the lower substrate or heater plate, the grooves and recess form the printhead ink channels and ink reservoir, respectively. The grooves are open at one end and closed at the other end. The channel open ends serve as the printhead nozzles. The channel closed ends are closely adjacent the reservoir and placed in fluid communication therewith by a patterned recess in the thick film layer. Each channel is capillarily filled with ink from the reservoir and has a heating element located upstream of the nozzles. Each heating element is selectively driven by electrical pulses representative of data signals to produce momentary vapor bubbles in the ink to effect the ejection of ink droplets from the printhead nozzles and propel them to a recording medium. The thick film layer is also patterned to expose the heating elements and thereby place the heating elements in a pit to better contain the vapor bubble and prevent ingestion of air.
This printhead construction has some drawbacks. For example, the silicon channel plate is anisotropically or orientation dependent etched to form straight, triangularly shaped grooves when non-straight grooves provides more design flexibility and non-triangular shaped nozzles assist in droplet directionality. In addition, an etched silicon channel plate means separate fabrication of the two plates and the necessity of very accurate alignment between the two when they are mated. Because silicon is opaque, it is difficult to determine if the adhesive is coating all of the surface areas required to separate the channels and to prevent internal ink leaks.
U.S. Pat. No. 5,132,707 discloses a thermal ink jet printhead having an array of coplanar nozzles in a nozzle face that are entirely surrounded by a polymeric material. The ink channels, nozzles, and ink reservoir are produced by sequentially depositing and patterning two layers of polymeric material, such as, for example, Vacrel®, on the heater plate, so that the heating elements are placed in a pit in the first layer and the channels and reservoir recesses are produced in the overlying second layer. The cover plate has a third layer of identical polymeric material with a hole through both the cover plate and third layer to serve as the ink inlet. The cover plate with the third layer is aligned and bonded to the second layer with the cover plate hole aligned with the reservoir recess in the second layer to produce the printhead.
U.S. Pat. No. 5,198,834 discloses a printhead or pen head for a droplet-on- demand ink jet printer or pen which utilizes a barrier wall located between a substrate and an orifice plate. The ink flows through the printhead in channels defined in the barrier wall. The barrier wall is fabricated in two layers from cured, photoimaged resist materials. One layer is a soldermask material, and the other is a photolithographic resist material. The two layers together resist chemical attack by the ink and separation of the orifice plate from the printhead.
Pending U.S. patent application Ser. No. 08/712,761, filed Sep. 12, 1996, entitled “Method and Materials For Fabricating An Ink Jet Printhead,” and assigned to the same assignee as the present invention discloses an ink jet fabrication technique which enables capillary channels for liquid ink to be formed with square or rectangular cross-sections. A sacrificial layer is placed over the main surface of a silicon chip, the sacrificial layer being patterned in the form of the void formed by the desired ink channels. A permanent layer comprising a permanent material is applied over the sacrificial layer and, after polishing the two layers to form a uniform layer which exposes some of the surfaces of the sacrificial layer, the sacrificial layer is removed to form open ink channels. A cover plate is bonded to the patterned permanent material to provide the closed ink channels and produce the printhead. Preferred sacrificial layer materials include polyimide while the preferred permanent layer materials include polyarylene ether ketone.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an ink jet printhead having a patternable ink channel structure which is formed directly on the heater plate, so that all of the critical alignments are done on the heater plate without the need for straight channels or separate channel plate.
In one aspect of the present invention, there is provided an ink jet printhead having a patternable ink channel structure comprising: a heater plate having on one surface thereof an array of heating elements, driving circuitry means, and interconnecting leads including contacts for the selective application of electrical pulses to each of the heating elements, each of the selectively applied pulses ejecting an ink droplet from the printhead; a passivation layer covering the heater plate surface and the addressing circuitry means and interconnecting leads thereon, the heating elements and contacts being free of the passivation layer; a patternable layer being deposited on the passivation layer and patterned to expose the contacts and to form a plurality of parallel channel grooves therein with opposing ends, each channel groove containing and exposing therein a heating element, one end of the channel grooves being open and each of the opposing ends being connected to a reservoir recess; and a cover plate having an aperture and being bonded to the patternable layer to form the ink channels from the channel grooves, a common reservoir from the reservoir recess, and nozzles from the channel open ends, the aperture in the cover plate being aligned with the common reservoir to provide an ink inlet for the printhead.
REFERENCES:
patent: Re. 32572 (1988-01-01), Hawkins et al.
patent: 4774530 (1988-09-01), Hawkins
patent: 4947192 (1990-08-01), Hawkins et al.
patent: 4947193 (1990-08-01), Deshpande
patent: 5132707 (1992-07-01), O'Neill
patent: 5198834 (1993-03-01), Childers et al.
patent: 5665249 (1997-09-01), Burke et al.
patent: 5686224 (1997-11-01), O'Neill
patent: 5699094 (1997-12-01), Burke et al.
patent: 5738799 (1998-04-01), Hawkins et al.
patent: 5820771 (1998-10-01), Burke et al.
patent: 5850234 (1998-12-01), Kneezel et al.
patent: 5870123 (1999-02-01), Lorenze, Jr. et al.
patent: 0 768 182 A2 (1997-04-01), None
Atkinson Diane
Burke Cathie J.
Calistri-Yeh Mildred
Fisher Almon P.
Arthur David J.
Moses Richard
Xerox Corporation
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