Printer orifice plate with mutually planarized ink flow barriers

Information

  • Patent Grant
  • 6523938
  • Patent Number
    6,523,938
  • Date Filed
    Monday, January 17, 2000
    25 years ago
  • Date Issued
    Tuesday, February 25, 2003
    21 years ago
Abstract
A printhead is used to eject printing fluid, such as ink, onto a printing medium. This printhead has an orifice plate defining plural orifices from which the printing fluid is individual ejecting into the printing medium to form characters and images. This orifice plate includes in addition to the plural orifices, plural barrier walls interdigitated with the orifices so that each orifice is between a pair of spaced apart barrier walls. The barrier walls substantially prevents the ejection of printing fluid from one selected orifice from causing an unwanted ejection of printing fluid from adjacent orifices.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




This invention relates generally to inkjet printing. More particularly, this invention relates to an inkjet print cartridge which has improved reliability, and improved ease and reliability of manufacturing. That is, the inkjet cartridge provides a robust design with reduced variability and improved manufacturing. The present invention also relates to an inkjet printer having such an inkjet print cartridge, and to a method for manufacturing such an inkjet print cartridge.




2. Related Technology




Inkjet printers or plotters typically have a print cartridge mounted on a carriage. This carriage is traversed back and forth across the width of a print medium (i.e., usually paper or a plastic plotting film, for example) as the print medium is fed through the printer or plotter. Plural orifices on the print cartridge are fed ink (or other printing fluid) by one or more channels communicating from a reservoir of the print cartridge. Energy applied individually to addressable resistors (or other energy-dissipating elements, for example, to piezoelectric actuators), transfers energy to printing fluid which is within or associated with selected ones of the plural orifices. This energy causes a portion of the printing fluid to momentarily convert to vapor phase and to form a vapor bubble. Thus, this type of printer is also sometimes referred to as a “bubble jet printer.” As a result of the formation and expansion of the vapor bubble, some of the ink is ejected out of the respective orifice toward the print medium (i.e., forming an “ink jet”). As the ink is ejected, the bubble collapses almost simultaneously, allowing more ink from the reservoir to fill the channel. This quick ejection of an ink jet from a selected orifice, and almost simultaneous collapse of the bubble which caused this ejection, allows for the ink jet printing cycle to have a high repetition rate.




The challenges of manufacturing such inkjet print cartridges are many. Among these challenges is the manufacturing of a fine-dimension orifice plate that forms a part of a printhead of the print cartridge. This orifice plate not only defines the plural fine-dimension orifices from which ink jets issue to the print medium, it also forms a part of the ink feed channel(s) bringing ink to the orifices. The orifice plate also defines plural barrier walls, each one of which is positioned between a pair of adjacent orifices. The respective barrier walls between adjacent orifices substantially prevent an ink ejection event at one orifice from causing ink to be ejected from an adjacent orifice.




Conventional ink jet print cartridges or components for such cartridges are seen in U.S. Pat. Nos. 3,930,260; 4,578,687; 4,677,447; 4,943,816; 5,560,837, and 5,706,039. However, none of these conventional ink jet print cartridges are believed to include an orifice plate with plural barrier walls each of which intimately cooperates with a print head thin film structure carried upon a substrate of the print cartridge.




SUMMARY OF INVENTION




In view of the deficiencies of the related technology, an object for this invention is to reduce or overcome one or more of these deficiencies.




Accordingly, the present invention provides an inkjet printhead for ejecting printing fluid during a printing event, the printhead comprising a substrate; a thin-film structure carried on the substrate, the thin-film structure including an energy-dissipating element for providing energy for ejecting printing fluid from the printhead during a printing event; a fine-dimension orifice plate attached to the thin-film structure and defining an orifice from which printing fluid is ejected during a printing event; the fine-dimension orifice plate including a pair of barrier walls spaced apart one on each side of the orifice, the barrier walls each defining a respective one of a pair of end edges, and the pair of end edges being coplanar with one another, whereby the pair of barrier walls at the pair of coplanar end edges each engage the thin-film structure.




According to another aspect, this invention provides a fluid printing cartridge for ejecting printing fluid onto a printing medium, the printing cartridge comprising: a cartridge body defining a printing fluid chamber, and a printing fluid delivery assembly; a printhead having a substrate and receiving printing fluid from the printing fluid chamber via the printing fluid delivery assembly to controllably eject this printing fluid onto the printing medium, the printhead including: a thin-film structure carried on the substrate and including an energy dissipating element for providing energy to the printing fluid to eject the printing fluid from the printhead, a fine-dimension orifice plate attached to the thin-film structure and defining an orifice from which printing fluid is ejected, the fine-dimension orifice plate including a pair of barrier walls spaced apart one on each side of the orifice, the pair of barrier walls each defining a respective one of a pair of end edges, and the pair of end edges being coplanar with one another so that the pair of barrier walls at the pair of end edges each engage the thin-film structure.




Still another aspect of the present invention provides a method of making a fluid jet print head, the method comprising steps of: providing a substrate; forming a thin-film structure on the substrate; including in the thin-film structure an energy-dissipating element for providing energy to eject printing fluid from the printhead; providing a fine-dimension orifice plate, forming in the fine-dimension orifice plate an orifice from which printing fluid is ejected, and a pair of barrier walls spaced apart one on each side of the orifice; utilizing the pair of barrier walls to each define a respective one of a pair of end edges, and forming the pair of end edges to each be coplanar with one another, whereby the pair of barrier walls at the pair of end edges each engage the thin-film structure.




Other objects, features, and advantages of the present invention will be apparent to those skilled in the pertinent arts from a consideration of the following detailed description of a single preferred exemplary embodiment of the invention, when taken in conjunction with the appended drawing figures, which will first be described briefly.











BRIEF DESCRIPTION OF THE DRAWING FIGURES





FIG. 1

is a diagrammatic side elevation view of an inkjet printer which uses an exemplary inkjet print cartridge embodying the present invention;





FIG. 2

provides a perspective view of an exemplary inkjet print cartridge, which may be used in the printer of

FIG. 1

, and with a portion of the inkjet print cartridge broken away for clarity of illustration;





FIG. 3

provides a plan-view of a printhead portion of the inkjet print cartridge seen in

FIG. 2

;





FIG. 4

provides a greatly enlarged plan view of a component part of the print head seen in

FIG. 3

, but shows the opposite side of this component;





FIG. 5

shows a manufacturing intermediate article which provides plural (256 in this case) component parts like that part seen in

FIG. 4

, and while these plural component parts are all integral with one another in the manufacturing intermediate article;





FIG. 6



a


provides a drawn illustration of a portion of the component part seen in

FIG. 4

at a first stage of manufacture, but is drawn in a still larger size than

FIG. 4

in order to provide clarity of illustration;





FIG. 6



b


is a fragmentary elevation view, partly in cross section, of a portion of the component part seen in

FIG. 6



a;







FIG. 6



c


is a microphotograph from which

FIG. 6



a


was drawn, and showing the same portion of a component part seen in

FIG. 4

, and at the same stage of manufacture;





FIGS. 7 and 8

show subsequent steps in the method of manufacturing a component part as is seen in

FIG. 4

;





FIG. 9



a


is a drawn illustration of the component part seen in

FIG. 6



a


, but showing the component subsequent to the manufacturing steps seen in

FIGS. 7 and 8

;





FIG. 9



b


is similar to

FIG. 6



b


, but shows the component part subsequent to the manufacturing steps of

FIGS. 7 and 8

;





FIG. 9



c


provides an elevation view similar to that of

FIG. 9



b


, but is taken orthogonally to the direction of view of

FIG. 9



b


; and





FIG. 9



d


is a microphotograph similar to that of

FIG. 6



c


, and is the photograph from which

FIG. 9



a


is drawn, but shows the component part subsequent to the manufacturing steps of FIGS.


7


and


8


.











DETAILED DESCRIPTION OF A PREFERRED EXEMPLARY EMBODIMENT OF THE INVENTION





FIG. 1

shows an exemplary inkjet printer


10


. This printer


10


includes a base


12


carrying a housing


14


. Within the housing


14


is a feed mechanism


16


for controllably moving a print medium (i.e., paper this case, although the invention is not so limited) through the printer


10


. Those ordinarily skilled in the pertinent arts will understand that the feed mechanism


16


may be configured to feed sheet paper or medium, or may be configured to feed roll paper or medium, or may be configured to feed print medium of another shape or style. In this exemplary printer


10


, the feed mechanism


16


controllably moves a single sheet of paper


18


from a paper magazine


20


along a print path


22


within the printer


10


. The printer


10


includes a traverse mechanism


24


(i.e., a carriage) carrying an inkjet print cartridge


26


. The traverse mechanism moves the inkjet printing cartridge


26


perpendicularly to the direction of movement of the paper


18


(i.e., the cartridge


26


is moved perpendicularly to the plane of FIG.


1


). The printer


10


uses the inkjet printing cartridge


26


to controllably place small droplets of printing fluid (i.e., ink, for example) from the inkjet printing cartridge


26


on the paper


18


. By moving the inkjet printing cartridge


26


repeatedly back and forth across the paper


18


as this paper is advanced by the feed mechanism


16


characters or images may be controllably formed by ejection and placement on the paper


18


of many small droplets of ink from the cartridge


26


. These small droplets of ink are ejected in the form of ink jets impinging on the paper


18


in controlled locations to form the desired characters and images, as will be well known to those ordinarily skilled in the pertinent arts.





FIG. 2

illustrates the exemplary inkjet printing cartridge


26


. This inkjet printing cartridge


26


includes a cartridge body


28


. The cartridge body includes a molded, generally rectangular, and cup-like body portion


28




a


; and a molded complimentary closure or lid portion


28




b


. From the lid portion


28




b


extends a tab


28




bb


, which provides for manual purchase on the print cartridge


28


. That is, the user of a print cartridge


28


may grasp the tab


28




bb


in order to, for example, insert the print cartridge into the carriage


24


of the printer


10


or to remove the print cartridge from this carriage. The body portion


28




a


defines a fluid delivery assembly (generally referenced with the numeral


30


) supplying printing fluid (such as ink) to a printhead


32


externally carried on this body portion


28




a


. The fluid delivery assembly


30


may include an open-cell, fine-grained sponge


34


carried within a chamber


36


of the body


28


, and a standpipe (not shown), conveying the printing fluid from the chamber


36


to the printhead


32


. The body portions


28




a


and


28




b


cooperatively define and bound the chamber


36


to receive the sponge


34


along with a supply of printing fluid (i.e., ink) within this chamber to the printhead


32


.




Those ordinarily skilled in the pertinent arts will understand that the printhead


32


includes a printing circuit


38


which electrically couples the printhead


32


with the printer


10


via circuit traces


38




a


and plural electrical contacts


40


. That is, the electrical contacts


40


individually make electrical contact with matching contacts (not seen in the drawing Figures) on the traverse mechanism


24


, and provide for electrical interface of the printhead


32


with electrical driving circuitry (also not illustrated in the drawing Figures) of the printer


10


. Individual ones of plural fine-dimension orifices


42


of the printhead


32


eject printing fluid when appropriate control signals are applied to selected ones of the plural contacts


40


. In other words, the fine-dimension orifices


42


controllably eject fine-dimension droplets of printing fluid onto the print medium


18


in order to form characters and images on this print medium.




The structure of the printhead


32


is shown in greater detail in FIG.


3


. This printhead


32


includes a substrate


44


which may be formed as a plate of glass (i.e., an amorphous, generally non-conductive material). In this exemplary preferred embodiment, the substrate


44


is generally rectangular in plan view, although the invention is not so limited. Most preferably, this glass substrate is an inexpensive type of soda/lime glass (i.e., like ordinary window glass), which makes the printhead


32


very economical to manufacture, The printhead


32


is especially economical and inexpensive to manufacture when considered in comparison to printheads using the conventional technologies requiring a substrate of silicon or other crystalline semiconductor materials.




On the glass substrate


44


is formed a thin-film structure


46


of plural layers. During manufacturing of the printhead


32


this thin-film structure


46


is formed substantially of plural thin-film layers applied one after the other, with each one formed atop of the earlier layers, and with each thin-film layer entirely covering and being congruent with the plan-view shape of the substrate


44


. Once selected ones of these thin-film layers are formed on the substrate


44


, subsequent patterning and etching operations are used to define the contacts


40


and print circuit


38


, for example. An example of a thin-film structure that may be used to form a printhead


32


includes a first metallic multi-function heat sink and radio frequency shield and ion barrier layer, which is applied upon the glass substrate


44


. This first layer may preferably be formed of chrome about 1 to 2 microns thick. Alternatively, the first layer may be formed of other metals and alloys. For example, the first thin-film heat sink and RF shield and ion barrier layer may be formed of aluminum, chrome, copper, gold, iron, molybdenum, nickel, palladium, platinum, tantalum, titanium, tungsten, a refractory metal, or of alloys of these or other metals.




Upon the first metallic thin-film layer may be formed an insulator thin-film layer. The insulator thin-film layer is preferably formed of silicon oxide, and is about 1 to 2 microns thick. Next, on the substrate


44


and upon the insulator layer may be formed a resistor thin-film layer. The thin-film resistor layer is preferably formed of tantalum aluminum alloy, and is preferably about 600 Angstroms thick. Next, over the resistor layer may be formed a metallic conductor thin-film layer. This metallic conductor thin-film layer is formed preferably of an aluminum based alloy, and is about 0.5 micron thick. This conductor layer is later patterned and etched back to cover only the area defining the traces


38




a


of print circuit


38


, and also the area defining the contacts


40


. This conductive layer is patterned and etched away at selected fine-dimension areas aligning individually with the fine-dimension orifices


42


in order to form fine-dimension resistors (not shown in the drawing Figures).




Over a portion of the traces


38


and over the individual resistors formed in the tantalum aluminum alloy resistive layer, an orifice plate


48


is adhesively secured to the thin-film structure


46


upon the substrate


44


. This orifice plate


48


defines the fine-dimension orifices


42


, defines a chamber (to be further described below) receiving ink from the reservoir


36


, and also defines plural spaced apart barrier walls


50


. The barrier walls


50


are interposed between each adjacent pair of the orifices


42


in the plate


48


, and extend from the plate


48


to the thin-film structure


46


on the substrate


44


.




Viewing now

FIG. 4

, an orifice plate


48


is illustrated greatly enlarged from its actual size. In reality, this orifice plate


48


is about one-quarter inch square, and is manufactured as a part of a sheet-like work piece (indicated with the numeral


48




a


) containing many of these orifice plates. For example, in

FIG. 5

is illustrated an exemplary manufacturing intermediate article, which is the work piece


48




a


, and which in this particular case includes a 16×16 array of the orifice plates


48


(i.e., 256 orifice plates) each integrally connected to its neighboring orifice plates to form the work piece


48




a


. Viewing

FIG. 4

in greater detail, it is seen that the work piece


48




a


defines plural elongate perforations


52


, which are aligned with one another in rows and columns to define separation lines. As a result, the individual orifice plates


48


can be separated from the work pieces


48




a


along these separation lines. As

FIG. 4

also illustrates, the individual orifice plates


48


each define a generally rectangular or square shape, of which a peripheral portion


54


is defined by plural cooperative upstanding ribs


56


. These ribs


56


allow the orifice plates


48


to be adhesively attached individually to the thin-film structure


46


of a printhead


32


. That is, the ribs


56


provide purchase for an adhesive to grip the orifice plate


48


. Each orifice plate


48


also defines a recess


58


, which is somewhat “piano” shaped, and which aligns with an ink feed hole (not illustrated in the drawing Figures) formed through the substrate


44


and through the thin-layer structure


46


in order to feed ink from chamber


36


to the fine-dimension orifices


42


. The recess


58


in cooperation with the adjacent fine-dimension structure


46


of the printhead


32


forms a fine-dimension capillary chamber (indicated with arrowed numeral


58




a


) for receiving this ink, as was mentioned earlier. This recess


58


(and chamber


58




a


) communicate with the orifices


42


, by way of plural channels


60


, each of which is defined between a pair of adjacent barrier walls


50


. The barrier walls


50


are integral with the orifice plate


48


, and extend toward and to the thin-film structure


46


on the substrate


44


, so that an end edge


64


of each of the barrier walls rests upon the thin-film structure.





FIGS. 6



a


,


6




b


, and


6




d


each illustrate the barrier walls


50


on plate member


48


at a stage of manufacture represented by FIG.


4


. That is, the barrier walls


50


at this stage of manufacture are rough, and define an end edge


64


with an end edge surface


64




a


which is similarly rough. Importantly, the end edge surfaces


64




a


of the plural barrier walls


50


are not necessarily planar with one another. If the orifice plate


48


were employed in this condition to make a printhead


32


, then not all of the barrier walls


50


would necessarily engage with the thin-film structure


46


on the substrate


44


. That is, the higher (i.e., longer) barrier walls


50


would likely engage the thin-film structure. But, the lower (i.e., shorter) barrier walls


50


may not engage well with the thin-film structure, and would allow gaps to exist between the end edge surfaces


64




a


of the barrier walls and the thin-film structure. These gaps could provide sufficient communication between the channels


60


that when an ink jet printing event is conducted at one of the channels, at least one of the adjacent ink channels would have ink ejected also from its orifice


42


. This ejection of ink from an orifice as a result of an ink jet printing operation at an adjacent orifice is called “cross talk,” and decreases the desirable operating characteristics of a print cartridge. In some cases, cross talk will be so bad that a cartridge is not usable.




However,

FIGS. 7 and 8

illustrate steps in a method of both smoothing and mutually planarizing the barrier walls


50


, so that a new end edge surface (to be referenced with numeral


64




b


) is formed on these barrier walls. Viewing now

FIG. 7

, it is seen that the work piece


48




a


is disposed upon a surface plate member


66


having an upper flat surface


66




a


. Interposed between the work piece member


48




a


and the surface


66




a


is a sheet


68


of fine abrasive material (i.e., abrasive cloth or paper, for example). The work piece member


48




a


is placed on the abrasive cloth or paper


68


with the side seen in

FIG. 4

downwardly. That is, the barrier walls


50


are disposed toward the abrasive cloth or paper


68


, and the end edges


64


(i.e., at surfaces


64




a


) of these barrier walls engage with the abrasive. On top of the work piece member


48




a


is placed an elastic conformal pad of comparatively soft, compliant, and resilient yieldably shape retaining material


70


. The pad


70


has a plan view shape substantially the same as that of work piece


48




a


. Over the pad


70


, a backing member


72


is placed. The backing member


72


has a central plate portion


72




a


of sufficient stiffness that pressure applied to this backing member (indicated by arrows


72




b


) urging it toward the surface plate


66


does not distort this backing member


72


significantly, and this backing member


72


evenly distributes the force


72




b


over the area of the backing member


72


and of work piece


48




a


. Thus, this force toward the surface plate


66


is applied to the pad


70


uniformly. As is seen in

FIG. 8

, the force


72




b


is sufficient to compress or distort the conformal member of the pad


70


over the entire area of the work piece


48




a.






The backing member


72


also includes a peripheral depending lip portion


74


, having an end edge


74




a


. The end edge


74




a


is uniformly dependent all about the perimeter of work piece


48




a


relative to the plate part


72




a


of the backing member


72


. As a result, as is seen in

FIG. 8

, the force


72




b


compresses the conformal pad


70


so that the end edge


74




a


engages the surface plate


66


all about the perimeter of the backing member


72


. This peripheral engagement of the depending lip


74


insures that parallelism of the plate portion


72




a


is maintained. Further, the conformal pad


70


insures that the force


72




b


is uniformly distributed over the area of the work piece


48




a.






Actually, it is seen that the backing member at end edge surface


74




a


engages the abrasive material


68


, although the method is not limited to this feature. That is, the plate portion


72




a


could be extended laterally sufficiently that the lip


74


and its end edge


74




a


contact the surface plate


66


and do not contact the abrasive material


68


. Further, as is seen in

FIG. 8

, the backing member and work piece


48




a


are moved relative to the abrasive material


68


while parallelism is maintained (as is indicated by arrows


76


). The yieldable shape retaining elasticity of the pad


70


controls the amount of force applied to the work piece


48




a


, and the pad


70


also insures that this force is applied uniformly while parallelism is maintained between plate


66


and plate portion


72




a


. Consequently, after a determined amount of time and motion


76


(or number of motion strokes, for example), the work piece


48




a


is removed from the apparatus seen in

FIGS. 7 and 8

.





FIGS. 9



a


-


9




d


illustrate the result of the process steps indicated in

FIGS. 7 and 8

. The barrier walls


50


now have a smooth, polished, and planarized end edge surface


64




b


. Further, as is seen in

FIG. 9



c


, these end edge surfaces


64




b


are also coplanar with one another, as is indicated by the dashed line in this Figure. As a result, when the orifice plate


48


is installed on a substrate


44


(i.e., on a thin-film structure


46


), the end edge surfaces


64




b


of the barrier walls


50


each make close and uniform contact with the thin-film structure


46


, which has a position at the dashed line of

FIG. 9



c


, and as is indicated by the arrowed numeral


46


. As a result, the occurrence of gaps between the barrier walls


50


and the thin-film structure


46


, and cross talk between adjacent orifices


42


during an ink jet ejection from an orifice


42


, are both substantially eliminated. Actual use of the present invention has demonstrated that ink jet print cartridges made according to and embodying this invention are substantially free of cross talk. On the other hand, ink jet cartridges made in all respects the same, except that they do not include planarizing of the barrier walls


50


, have a significant occurrence of cross talk, and in some cases this condition is so severe that the print cartridge is not usable.




Those skilled in the art will further appreciate that the present invention may be embodied in other specific forms without departing from the spirit or central attributes thereof. Because the foregoing description of the present invention discloses only a particularly preferred exemplary embodiment of the invention, it is to be understood that other variations are recognized as being within the scope of the present invention. For example, those ordinarily skilled in the pertinent arts will recognize that the method diagrammatically illustrated and described with reference to

FIGS. 7 and 8

is a form of lapping. Thus, it is apparent that this and other forms of lapping and abrasive planarizing may be used to practice the method of this invention. Accordingly, the present invention is not limited to the particular embodiment which has been described in detail herein. Rather, reference should be made to the appended claims which define the spirit and scope of the present invention.



Claims
  • 1. A fluid jet printer having multiple fluid ejection orifices, said printer comprising:a base carrying a housing defining a printing path, a print medium feed mechanism controllably moving print medium through said printer along said printing path, a carriage for holding a fluid jet print cartridge over said printing path, said fluid jet print cartridge including: a cartridge body defining a printing fluid chamber, and a printing fluid delivery assembly; and a printhead having a substrate, said print head receiving printing fluid from said printing fluid chamber via said printing fluid delivery assembly and controllably ejecting this printing fluid onto the print medium, said print head including: a thin-film structure carried on said substrate and including an energy dissipating clement for providing energy to said printing fluid to eject the printing fluid from the printhead; and an orifice plate with multiple fluid ejection orifices respectively separated by barrier walls having mutually coplanarized end edges which present a smooth surface for engagement contact with said thin-film structure, said orifice plate securely attached to said thin-film structure by a plurality of upstanding ribs at a peripheral portion of said orifice plate; and printing circuit that electrically couples the printing head with the printer via circuit traces connected to said energy dissipating element.
  • 2. A printhead for ejecting printing fluid during a printing event, said printhead comprising:a substrate, a thin-film structure carried on said substrate, said thin-film structure including an energy-dissipating element for providing energy for ejecting printing fluid from said printhead during a printing event, and said thin-film structure defining a surface disposed away from said substrate; an orifice plate originally formed integral with other like orifice plates and attached to said thin-film structure by a plurality of upstanding spaced apart peripheral ribs, and including a wall portion which is spaced from said surface of said thin-film structure to define a chamber receiving printing fluid, said wall portion of said orifice plate also defining a plurality of orifices respectively separated by upstanding barriers having mutually coplanarized end edges which present an abrasively truncated smooth surface for engagement contact with said thin-film structure.
  • 3. The printhead of claim 2 wherein said substrate is formed of glass.
  • 4. The printhead of claim 2 wherein said thin-film structure includes:a metallic heat sink layer on said substrate; an insulative layer on said heat sink layer; a resistive layer on said insulative layer; a conductive layer on said resistive layer; and a passivating layer on said conductive layer.
  • 5. The printhead of claim 4 wherein said heat sink layer is formed of a metal selected from the group consisting of: aluminum, chrome, copper, gold, iron, molybdenum, nickel, palladium, platinum, tantalum, titanium, tungsten, a refractory metal, and alloys of these or other metals.
  • 6. The printhead of claim 4 wherein said insulative layer includes silicon oxide.
  • 7. The printhead of claim 4 wherein said resistive layer includes tantalum aluminum alloy.
  • 8. The printhead of claim 4 wherein said conductive layer includes aluminum.
  • 9. The printhead of claim 4 wherein said passivation layer includes silicon.
US Referenced Citations (8)
Number Name Date Kind
3930260 Sicking Dec 1975 A
4528577 Cloutier et al. Jul 1985 A
4578687 Cloutier et al. Mar 1986 A
4616408 Lloyd Oct 1986 A
4677447 Nielsen Jun 1987 A
4943816 Sporer Jul 1990 A
5560837 Trueba Oct 1996 A
5706039 Chamberlain et al. Jan 1998 A