Patent Publication Number: US-6663224-B2

Title: Orifice plate with break tabs and method of manufacturing

Description:
FIELD OF THE INVENTION 
     This invention relates to ink jet printers, and particularly manufacture of orifice plates for use with ink jet printers and assembly therewith. 
     BACKGROUND 
     Generally, thermal ink jet printers have a print cartridge. The print cartridge often includes a print head having an orifice plate defining one or more arrays of numerous orifices through which droplets of fluid are expelled onto a medium to generate a desired pattern. 
     An orifice plate has a core plate material that is typically formed of a metal. Typically, an area of the core plate material is exposed during the manufacturing process. Often, the metals forming the core plate material are susceptible to corrosion by some fluids used in the cartridges. Further, the metal in the orifice plate sometimes forms a galvanic cell with some of the fluids used in the cartridge. With corrosion or the formation of a galvanic cell with the orifice plate, the cartridge is more likely to be rendered inoperable prematurely. 
     Often the exposed areas of the plate are encapsulated with an inert coating. However, the coating often extends over the plate to at least partially block the orifices through which fluid is to be expelled in a printing process. Consequently, an adequate margin between the orifices and exposed areas is employed. The size of the print head die onto which the plate is attached is thereby directly affected. It is desired to minimize the size of the print head die due to the costs associated with the material used therein. Accordingly, it is desired to manufacture orifice plates that minimize print head die size, resist corrosion and minimize galvanic cell formation. 
     SUMMARY 
     In one embodiment, a plate has a rectangular plate body with a plurality of nozzle arrays. The plate also has first and second end zones in between the plurality of nozzle arrays and opposing ends of the plate body, respectively. There is a break tab in at least one of the first and second end zones. In between the first and second end zones is a middle zone. A plating material encapsulates the plate body in the middle zone. 
     Many of the attendant features of this invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description and considered in connection with the accompanying drawings in which like reference symbols designate like parts throughout. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of a sheet of intercoupled orifice plates according to one embodiment of the invention. 
     FIG. 2 is an enlarged view of section  2  of FIG.  1 . 
     FIG. 3A is an enlarged view of section  3  of FIG.  2 . 
     FIG. 3B is another embodiment of the enlarged view of section  3  of FIG.  2 . 
     FIG. 4 is a perspective view of an ink jet cartridge including an orifice plate according to the embodiment of FIG.  1 . 
     FIG. 5 is an enlarged schematic sectional view of the ink jet cartridge of FIG. 4, taken along section  5 — 5 . 
     FIG. 6 is an enlarged plan view of an alternative configuration for a sheet of orifice plates. 
     FIG. 7 is an enlarged plan view of another alternative configuration for a sheet of orifice plates. 
     FIG. 8 is an enlarged plan view of another alternative configuration for a sheet of orifice plates. 
     FIG. 9 is an enlarged plan view of another alternative configuration for a sheet of orifice plates. 
    
    
     DETAILED DESCRIPTION 
     In the embodiment shown in FIG. 1, a sheet  10  has a multitude of intercoupled orifice plates  12 . The sheet includes a peripheral frame  14  that surrounds the plates, and that provides structural support of the sheet and alignment of the plates. 
     In one embodiment, the plates  12  are arranged in rows  20  and columns  22 , with more columns than rows. In one embodiment, the rows  20  are staggered, in that the plates of one row are offset from the plates of the adjacent rows. In the embodiment shown in FIG. 1, the offset is about one half the center-to-center spacing of the plates every other row. 
     In one embodiment, the sheet  10  is a square. In the embodiment illustrated, the sheet has sides of about 190 mm in length. In another embodiment, the sheet has a length and width found in a range of about 150 to 500 mm. In other embodiments the sheet length and width are determined by a desired number of plates per sheet, and/or a desire to have a sheet size that is compatible with manufacturing equipment sizes. A sheet thickness (and thus plate thickness) is about 29 μm. In alternative embodiments, the sheet thickness is found in a range from about 15 to 55 μm. The frame has a width of approximately 20 mm around the sides of the sheet. In alternative embodiments, the frame has a width that is found in a range from about 10 to 100 mm. In one embodiment, the frame size is determined based on the desired level of sheet structural integrity and stiffness. 
     In the embodiment shown in FIG. 2, each plate  12  is substantially identical to the other plates in the sheet  10 . In alternative embodiments, the sheet has different plate designs. In one embodiment, each plate is an elongated rectangle having a width of about 2.7 mm and a length of about 10.6 mm. In another embodiment, the width is about 2.2 mm. In another embodiment, the width is about 2.6 mm. In another embodiment, the width is about 3.5 mm. In another embodiment, the width is about 7 mm and the length is about 7.6 mm. In another embodiment, the width of the plate is found in a range of from about 2 to 20 mm, and the length is found in a range from about 5 to 20 mm. In another embodiment, the length and width of the plate depends on the demands of the application, including desired swath height, number of orifice arrays, and resolution. In one embodiment, the plate has an aspect ratio of about 4:1. In another embodiment, the aspect ratio is found in a range of from about 1:1 up to 8:1, for longer orifice arrays. 
     Each plate  12  has opposed first and second end edges  24 ,  26 , and opposed first and second side edges  30 ,  32 . In the embodiment shown in FIG. 2, the end edges are along plate sides which are shorter than those of the side edges. 
     In one embodiment, the sheet of plates has a core plate material. In one embodiment, the core plate material is plated over a substrate. In one embodiment, the substrate is glass, in another the substrate is metal. In one embodiment, the core plate material is nickel. The core plate material is peeled from the substrate and dipped into an electroplating bath to coat with a plating material  80  or protective coating. In another embodiment, the core plate material is formed by dipping a metal form into an electroplating bath and plating the metal form with a combination of nickel and a plating material  80 . The plating is then peeled off the metal form to become the sheet of orifice plates. 
     In one embodiment, the plating material  80  is gold or another precious metal, such as palladium (Ni—Rh, Ni—Pd, or Ni—Au). In one embodiment, the plating material  80  is corrosion resistant. These sheets are generally 20 to 50 μm thick. In one embodiment, the core plate material is nickel with a thickness of about 27 μm, and is coated with palladium having a thickness of about 1.5 μm. The plates in the sheet and break tabs therebetween are formed in the plating process. In alternative embodiments, the nickel plating ranges between about 13 to 53 μm, and the palladium thickness ranges between 0.3 to 2.0 μm. In another embodiment, the amount of precious metal is minimized, while plating reliability is maintained. 
     The sheet of plates has opposing surfaces which are plated with the plating material  80 . Additionally, the end edges  24 ,  26 , including the break tabs, and the side edges  30 ,  32  of the plates are plated with the plating material  80 . 
     In the embodiment illustrated in FIG. 2, the plate  12  includes four arrays  34  of nozzles  36 . In one embodiment, each of the four nozzle arrays corresponds to a different color that is supplied from a fluid reservoir or fluid chamber in a printer cartridge. In an alternative embodiment, the number of arrays in the plate range from about 1-12. In another embodiment, at least two of the nozzle arrays correspond to a same color. 
     Each plate  12  is coupled with the sheet  10  using at least one break tab  40 . In the embodiment illustrated in FIG. 2, there are four small break tabs  40   a ,  40   b ,  40   c ,  40   d  for the plate  12 . The break tabs  40   a ,  40   b  extend from the end edge  24  of the plate. The break tabs  40   c  and  40   d  extend from the end edge  26  of the plate. The break tabs  40   a  and  40   b , and the break tabs  40   c  and  40   d , are spaced apart from each other along the end edges  24  and  26 , respectively. In the embodiment shown, the side edges  30 ,  32  of each plate are substantially straight, and do not include break tabs. This embodiment with no break tabs on the side edges enables the adjacent plates to be fabricated in closer proximity, which in turn provides the economic advantage of more plates per sheet. In one embodiment, the gap between the adjacent plates is about 120 μm. In another embodiment, the gap between the adjacent plates is about 80 to 120 μm, in particular, 80 to 100 μm. 
     For each break tab  40  in the plate  12 , there is a corresponding break tab  40  in one of the plates that are adjacent. The break tabs  40  of the adjacent plates are coupled with each other, thereby coupling the adjacent plates in the sheet. 
     The sheet has an end column adjacent the frame portion  48 . In the embodiment shown in FIG. 2, the rows  20  of the plates in the sheet are staggered giving an outer edge of the end column  22  a corrugated shape. Along the end column are exterior end plates  52   a  and interior end plates  52   b . The plates in the end column alternate between the exterior end plate  52   a  and the interior end plate  52   b . In the embodiment shown, the exterior end plates  52   a  extend about half the width of a plate past the interior end plates  52   b.    
     In one embodiment, along sides of the frame is a frame portion  48 . The frame portion  48  has an interior boundary  49 . The interior boundary  49  corresponds with the end column of the sheet of plates such that there is a substantially consistently sized gap  51  in between the end column and the interior boundary. The interior boundary  49  has a shape that corresponds to the shape of the outer edge of the end column  22 . Accordingly, the interior boundary  49  is shaped in a corrugated shape opposite to the corrugated shape of the end column of FIG.  2 . 
     The interior boundary  49  has protruding portions  50   a  that correspond to the interior end plate  52   b , and thus the protruding portions  50   a  have the same length as the plates. Likewise, the interior boundary  49  has indented portions  50   b  that correspond to the exterior end plate  52   a . The indented portions  50   b  receive the adjacent exterior end plate  52   a  in the staggered configuration. 
     In one embodiment, the sheet of plates is attached to the frame in the same manner as the plates are coupled to their adjacent plates. The exterior end plate  52   a  has a break tab  53  that extends from both end edges of the plate  52   a . The break tab  53  couples with corresponding a break tab along the interior boundary  49  of the frame, as shown in FIG.  2 . In one embodiment, a top row  20   a  and a bottom row  20   b  of plates are coupled to the frame through the break tabs  40  along the top end edges and bottom end edges of the plates, respectively. The interior boundary  49  adjacent the top row  20   a  and the bottom row  20   b  of plates has break tabs that correspond to the break tabs  40 . 
     The plates  12  that are adjacent in one of the rows  20  are spaced apart by an I-shaped elongated gap  54  that extends the length of the plate. Flanges of the I-shaped gap are end segments  57  formed substantially perpendicular to a web portion of the gap  54 . The gap  54  terminates at each end segment  57  by abutting one of the end edges  24 ,  26  of the plate in the adjacent row. The end segment  57  has a length determined by the distance between two adjacent break tabs. Thus, a total length of any gap  54  is greater than the length of the side edge  30 , because the length of the end gap segments  57  are included in the total length. In another embodiment, a length of the gap  54  corresponds to the longest span of unsupported plate material. A width of the gap  54 , including end segment  57 , is about 120 μm between adjacent plates and adjacent rows. In alternative embodiments, the gap width ranges from about 20 to 200 μm. In another embodiment, the gap width is minimized to allow more plates per sheet. 
     Each break tab of the plate  12  is coupled to a different one of the plates in one of the adjacent rows. The plate  12  is coupled with plates  12   a ,  12   b ,  12   c , and  12   d . The plates  12   a  and  12   b  are in the adjacent row above the plate  12 , while the plates  12   c  and  12   d  are in the adjacent row below the plate  12 . The break tabs  40   a ,  40   b ,  40   c , and  40   d  couples the plate  12  with the plates  12   a ,  12   b ,  12   c  and  12   d , respectively. 
     In one embodiment, adjacent plates in a common row are indirectly coupled through plates in adjacent rows. In particular the plate  12  is indirectly coupled with plates  12   e ,  12   f  that are in the same row as the plate  12 . The plate  12   e  is coupled with the plate  12  through either the plate  12   a  or the plate  12   c . The plate  12   f  is coupled with the plate  12  through either the plate  12   b  or the plate  12   d.    
     In the embodiment shown in FIG. 2, the break tabs of the plates in one of the rows are aligned with the break tabs of the plates in the adjacent rows. As described in the application, the rows are each offset from adjacent rows a distance that is equal to a distance between adjacent break tabs. In this manner, the break tabs align with the break tabs in the adjacent rows, except for break tabs at the ends of the rows. The break tabs at the end of the rows are in plates  52   a  and couple with the interior boundary  49 , as described above. 
     In one embodiment, the break tabs are spaced apart evenly on the sheet at about half a pitch  55  of the plates. The pitch  55  is the distance between a center line of one plate to a centerline of an adjacent plate. The even spacing of the break tabs permits the stagger amount of about one-half the pitch between rows. In one embodiment, the break tab spacing on each plate is only slightly more than half the width of the plate. 
     In one embodiment, the nozzle arrays  34  are in a rectangular zone. As shown in FIG. 2, the plate  12  has an end peripheral zone  56  from each end edge  24 ,  26  to the rectangular zone of the arrays  34 . The plate  12  has an side peripheral zone  58  from each side edge  30 ,  32  to the rectangular zone of the arrays  34 . The end peripheral zone is about 982 μm wide. The side peripheral zone  58  is about 165 μm wide. In alternative embodiments, the values of the width of the end and side zones  56 ,  58  range from between about 800 to 1000 μm, and from between about 100 to 800 μm, respectively. With the narrow elongated plate shape, the end zones  56  are relatively small compared with the total plate area. The end zones  56  are intended to provide adequate margin for encapsulation of exposed broken end surfaces of the break tabs, as discussed in more detail below. In between the end zones  56  is a middle zone, and in the middle zone is the rectangular array of orifices. 
     In one embodiment, each break tab  40  has a shape of a trapezoid. Due to the shape of the break tabs, at a junction of the break tabs from adjacent plates, there is a cross-sectional area that is narrower than other areas of the break tabs. The narrower areas maximize the likelihood that a fracture occurs at the junction and away from the end edge of the plates. In alternative embodiments, the break tab is of another shape having a necked configuration, or is a straight-sided rectangular bridge to the adjacent plate. In an embodiment where a disjunction location is determined independently of the shape of the break tab, as described in more detail below, the shape of the break tab is any feasible shape. 
     In the embodiment shown in FIG. 3A, the break tab  40   a  of sheet  12  and the break tab  40  of the adjacent sheet  12   a  are coupled when in a first position. FIG. 3B shows the break tabs  40 ,  40   a  in a second position, wherein the break tabs have been separated along break area  59 , as described in more detail below. 
     As shown in FIGS. 3A and 3B, the break tab  40   a  has a wide base portion  42  coupled with and aligned with the end edge  24 . The wide base portion  42  has a length that ranges from about 320 μm to 500 μm, depending upon the application. The break tab  40   a  extends away from the end edge  24 , as the wide base portion  42  tapers to a nose portion  44 . The break tab  40  of the adjacent sheet  12   a  also has a nose portion  46  that corresponds to the nose portion  44 . The nose portion  44  has a length of about 180 μm for break tabs with shorter wide base portion lengths. At ends of the nose portion  44  and the nose portion  46  are indented (or concave) sections  47 . These indented sections  47  are aligned with the break area  59 . 
     In the embodiment shown in FIG. 2, the break tabs are aligned along cut lines (or break lines or break areas)  59  and end segments  57 . The break areas  59  are substantially straight, parallel gaps that define divisions between rows. The plates in the sheet are separated from each other upon separation of the break tabs at the break areas. In this embodiment, singulation of the plates is enabled by substantially parallel and straight cuts, as will be discussed below. As shown in FIG. 4, in one embodiment, after the plates are singulated, end surfaces  60  of the break tabs are exposed with the core plate material, while the rest of the plate  12  is plated. 
     In one embodiment, the singulation of the plates in the sheet is accomplished by bending the sheet at the break areas  59 . In one embodiment, the break tabs are bent so sharply that they rupture and break, thereby breaking the plates apart from each other. In one embodiment, a tool is positioned along the break area, and the sheet is bent around the tool. In one embodiment, a sharp edge of the tool is placed along the break area. In another embodiment, a rolling cutter is rolled over the break area to bend and break the break tabs apart. In one embodiment, the break tabs are formed of a sufficiently brittle material to break in a substantially efficient manner. 
     In another embodiment, the singulation is conducted using a mechanical shear having a substantially straight line of cutting. The shear severs the plates of each row from those of the adjacent row by cutting the line of break tabs along cut lines  59 , as illustrated in FIG.  2 . The entire sheet is singulated by a sequence of shearing cuts, with a cut for each line of break tabs equal to the number of rows plus one additional cut. After these row cuts are made, the plates are entirely singulated. In one embodiment, a significant manufacturing rate of singulated orifice plates is achieved using this series of row cuts. 
     An alternative singulating process uses laser cutting of the break tabs along the break lines. In this embodiment, the break area  59  is determined independently of the shape of the break tab. Consequently, the shape of the break tab is any feasible shape. In other embodiments where the break area is determined independently of the break tab shape, the break tab has any feasible shape. 
     As shown in FIGS. 4 and 5, the singulated plate  12  is applied over a barrier layer  82 . The barrier layer  82  defines firing chambers that align with the orifices  36  in the plate. Under the barrier layer  82  is an integrated circuit  65  with arrays of resistors corresponding to the firing chambers. The integrated circuit  65 , together with the barrier layer and the orifice plate are part of a print head  64 . 
     In the embodiment shown in FIG. 4, an inkjet cartridge body  62  has a recessed area for receipt of the print head  64 . In one embodiment, the print head  64  is bonded to the cartridge body  62  with structural adhesive. In one embodiment, fluid conduit(s) are located at a bottom of the recessed area. The conduit conveys one or more colors of fluid from fluid chambers within the cartridge into a slot in the print head  64 , which is fluidically coupled with the firing chambers. In one embodiment, the barrier layer  82  acts a gasket to prevent fluid flow between adjacent orifices. The fluid is heated in the firing chambers by the resistors and expelled from the corresponding nozzle orifice  36 . 
     As shown in FIGS. 4 and 5, along ends of the print head  64  are bond pads  74 . In one embodiment, there are  19  bond pads along each end. A circuit element  70  includes conductive tabs  72  that extend to contact with the bond pads  74 . The circuit element  70  electrically couples the print head with a printer. 
     In one embodiment, an insulating layer  76  is applied at each end of the print head. In another embodiment, the insulating layer is a bead of encapsulant. In one embodiment, the layer  76  is room temperature vulcanizing silicon rubber. In another embodiment, the layer  76  is a low temperature curing epoxy-based material. In one embodiment, the insulating layer  76  protects elements that are covered from corrosion. 
     In one embodiment, the insulating layer  76  encapsulates the end surfaces  60  of the break tabs, the bond pad  74  and the conductive tabs  72 . In one embodiment, the encapsulant covers the entire length of each end edge  24 ,  26 , as well as extends onto the surface of the plate. The encapsulant extends at least partially into the end zone  56 , described with regard to FIG.  2 . In this embodiment, having the break tabs along the end edges  24 ,  26  allows encapsulation of the break tabs with a margin of error: the length of the end zone  56 . In this manner, encapsulation of the orifices  36  is substantially avoided. In another embodiment, the encapsulant extends over less than 300 μm onto the surface of the plate. 
     In one embodiment, the exposed end surface of the break tab is not encapsulated by the insulating layer  76 . In one embodiment, the core plate material does not negatively react with some fluid chemistries to which the embodiment is exposed. 
     FIG. 6 is a partial plan view of an alternative configuration of a sheet  110  of orifice plates  112 . Unlike the embodiment of FIG. 2, the plates have break tabs  114  along side edges  130 , instead of shorter end edges  124 . Offset rows  120 , staggered columns  122 , and break tab  114  couplings in the sheet  110 , as well as other features are similar to that described with respect to the embodiment of FIG.  2 . Differences between this embodiment and that described with respect to FIG. 2 include orientation of the rows of the plates  112 . In FIG. 6, the end edge  124  of the plate couples with the end edge  124  of the adjacent plate in the same row. In this arrangement, comparatively there are more rows  120  in the sheet, each row with fewer plates. In one embodiment, when the singulated plate  112  is positioned onto the rest of the printhead, the insulating layer  76  does cover the break tabs  114  along the side edges  130 . In another embodiment, the insulating layer  76  does not cover the break tabs  114 . Break areas  159  are similar to break areas  59  described with respect to FIG.  2 . 
     FIG. 7 is a partial plan view of an alternative configuration of a sheet  210  of orifice plates  212 . The embodiment is similar to the embodiment described with respect to FIG.  2 . Similar to FIG. 2, the plates have break tabs  240  along end edges  224 , and the plates have similar end zones  256 . Unlike the embodiment of FIG. 2, the plates are aligned in both rows  220  and columns  222 , as shown in FIG.  7 . In addition, unlike FIG. 2, side edges  230  have break tabs  241  in the end zone  256 . In this embodiment, when the singulated plate  212  is positioned onto the rest of the printhead, the insulating layer covers the break tabs  240  along the end edges  224 , and covers the break tabs  241  along the side edges  230 . 
     In contrast to the above described embodiment of FIG. 2, singulating the plates from the sheet  210 , and other embodiments in which plates are laterally intercoupled, is less efficient. In particular, after the matrix is cut into separate rows, each row is then cut into individual plates, which substantially slows the singulation process. For example, in an embodiment where there are five rows and five columns, using the configuration of FIG. 2, there are six total cuts along the break areas in between the rows. However, using the configuration of FIG. 7, there would be six cuts in between the rows, and six cuts in between the columns, assuming that the individual rows remained substantially intact in the frame. 
     FIG. 8 illustrates a partial plan view of an alternative configuration of a sheet  310  of plates  312 . The embodiment is similar to the embodiment described with respect to FIG.  2 . Unlike the embodiment of FIG. 2, the plates are aligned in both rows  320  and columns  322 , as shown in FIG.  8 . Also, in this embodiment, each plate  312  has break tabs  340  in each of four corners  314  of the plate. The break tabs are able to be separated from each other or cut in a similar manner along break area  359 . Because the break tabs are along the break area  359 , when the break tabs  340  are cut at the break area  359 , the plates  312  singulate accordingly (similarly to the embodiment described in FIG.  2 ). Along an interior boundary of the frame, the plates  312  are coupled therewith at the corners  314 . In this embodiment, when the singulated plate  312  is positioned onto the rest of the printhead, the insulating layer covers the end edges  324 , and includes the corner break tabs  340 . 
     FIG. 9 illustrates a partial plan view of an alternative configuration of a sheet  410  of plates  412 . The embodiment is similar to the embodiment described with respect to FIG.  2 . However, unlike the embodiment of FIG. 2, rows  420  of FIG. 9 are offset by about one-third (⅓) with respect to adjacent rows. In one embodiment, each plate  412  has three break tabs  440  along both end edges  424 ,  426 . The break tabs  440  includes two break tabs  440   a , and break tab  440   b . The break tabs  440   a  couples the plate  412  with plate  412   a  in the adjacent row. The break tab  440   b  couples the plate  412  with plate  412   b  in the adjacent row. In one embodiment, each of the break tabs  440  are spaced from each other by a distance of about one-third (⅓) of an end edge length. The break tabs are able to be separated from each other or cut in a manner described above along break area  459 . 
     Although this invention has been described in certain specific embodiments, many additional modifications and variations will be apparent to those skilled in the art. For example, in one embodiment the columns and rows in the sheet of plates are substantially aligned (similar to the embodiments shown in FIGS.  7  and  8 ). In another embodiment, the rows in the sheet are offset by less than half the width of the plate. In another embodiment, the rows in the sheet are offset by more than half the width of the plate. In one embodiment the rows are offset from each other by about ¼ of a plate width. In this embodiment, there are four (4) break tabs along each end edge. One of the four break tabs along the plate end edge is coupled with a first plate in an adjacent row, while the remaining three break tabs are coupled with a second plate adjacent the first plate in the adjacent row. In the embodiment, the break tabs are separated from each other along the row by about ¼ of the end edge length. 
     In one embodiment, there is one break tab on each end edge of the plate. In another embodiment, there are a plurality of break tabs on each end edge of the plate. In another embodiment, there are more than two (2) break tabs along each end edge of the plate. In one embodiment, the break tabs are symmetrical about a longitudinal axis in the plate. In one embodiment, the break tabs are in the corners of the plates as well as along the end edges of the plates. 
     In one embodiment, the break tabs are spaced apart along the end edge of the plate by greater than half the width of the plate. In one embodiment, the break tabs are spread out substantially evenly along the end edge of the plate. In another embodiment, the break tabs are spaced apart along the end edge of the plate by less than half of the width of the plate. In another embodiment, the break tabs are spread out substantially evenly along the row. In one embodiment with four break tabs, the break tabs are spaced apart in the row by about ¼ of the end edge length. 
     It is therefore to be understood that this invention may be practiced otherwise than as specifically described. Thus, the present embodiments of the invention should be considered in all respects as illustrative and not restrictive, the scope of the invention to be indicated by the appended claims rather than the foregoing description.