Abstract:
An inkjet printhead includes a compact substrate of increased stability and structural integrity to provide a high resolution 600 dot-per-inch nozzle array having a one-half inch swath. A plurality of ink vaporization chambers are respectively aligned with the nozzles in two longitudinal columns, one column extending longitudinally along one edge of the substrate and a second column extending longitudinally along an opposite edge of the substrate, with ink feed channels communicating through an ink passage from an underside of the substrate around both edges of the substrate to the vaporization chambers. The ink feed channels have thereby been eliminated from the central portion of the substrate, and replaced by the ink feed channels at the edges of the substrate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of copending Ser. No. 08/893,775 filed Jul. 11, 1997, now U.S. Pat. No. 5,984,464, which is a continuation of Ser. No. 08/319,894 filed Oct. 6, 1994, now U.S. Pat. No. 5,648,806, which is a CIP of Ser. No. 08/179,866 filed Jan. 11, 1994, now U.S. Pat. No. 5,625,396, which is a continuation of Ser. No. 07/862,086 filed Apr. 2, 1992, now U.S. Pat. No. 5,278,584. The aforesaid Ser. No. 08/319,894 is also a CIP of Ser. No. 08/145,261 filed Oct. 29, 1993, now U.S. Pat. No. 5,949,453. 
     This application also relates to the subject matter disclosed in the following U.S. Pat. No. 5,949,453 and U.S. Applications: 
     U.S. application Ser. No. 07/864,822 now U.S. Pat. No. 5,420,627, filed Apr. 2, 1992, entitled “Improved Inkjet Printhead;” 
     U.S. application Ser. No. 07/864,930, filed Apr. 2, 1992, entitled “Structure and Method for Aligning a Substrate With Respect to Orifices in an Inkjet Printhead;” now issued as U.S. Pat. No. 5,297,331. 
     U.S. application Ser. No. 08/236,915, filed Apr. 29, 1994, entitled “Thermal Inkjet Printer Printhead now U.S. Pat. No. 5,635,968;” 
     U.S. application Ser. No. 08/235,610 now U.S. Pat. No. 5,635,966, filed Apr. 29, 1994, entitled “Edge Feed Ink Delivery Thermal Inkjet Printhead Structure and Method of Fabrication;” 
     U.S. Pat. No. 4,719,477 to Hess, entitled “Integrated Thermal Ink Jet Printhead and Method of Manufacture;” 
     U.S. Pat. No. 5,122,812 to Hess, et al., entitled “Thermal Inkjet Printhead Having Driver Circuitry Thereon and Method for Making the Same”; and 
     U.S. Pat. No. 5,159,353 to Fasen, et al., entitled “Thermal Inkjet Printhead Structure and Method for Making the Same”; and 
     U.S. application filed herewith, entitled “Inkjet Printhead Architecture for High Speed and High Resolution Printing”, U.S. application Ser. No. 08/319,986, filed Oct. 6, 1994, now U.S. Pat. No. 5,648,805; and 
     U.S. application filed herewith, entitled “Inkjet Printhead Architecture for High Frequency Operation”, U.S. application Ser. No. 08/319,404, filed Oct. 6, 1994, now U.S. Pat. No. 5,604,519; and 
     U.S. application filed herewith, entitled “High Density Nozzle Array for Inkjet Printhead”, U.S. application Ser. No. 08/319,892 filed Oct. 6, 1994, now U.S. Pat. No. 5,638,701; and 
     U.S. application filed herewith, entitled “Inkjet Printhead Architecture for High Speed Ink Firing Chamber Refill”, U.S. application Ser. No. 08/320,684, filed Oct. 6, 1994 now U.S. Pat. No. 5,563,642; and 
     U.S. application filed herewith, entitled “Ink Channel Structure Inkjet Printhead”, U.S. application Ser. No. 08/319,893 now U.S. Pat. No. 5,594,481; and 
     U.S. application filed herewith, entitled “Compact Inkjet Substrate with a Minimal Number of Circuit Interconnects Located at the End Thereof”, U.S. application Ser. No. 08/319,895 filed Oct. 6, 1994 now U.S. Pat. No. 5,568,171; and 
     U.S. application filed herewith, entitled “Self-Cooling Structure for Inkjet Substrate with High Density High Frequency Firing Chambers and Multiple Substrate Circuitry Elements”, U.S. application Ser. No. 08/648,471 filed May 15, 1996 now U.S. Pat. No. 5,619,236; and 
     U.S. application filed herewith, entitled “Compact Inkjet Stbstrate with Centrally Located Circuitry and Edge Feed Ink Channels”, U.S. application Ser. No. 08/319,405 filed Oct. 6, 1994 now U.S. Pat. No. 5,648,804. 
     The above patents and applications are assigned to the present assignee and are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention generally relates to inkjet and other types of printers and, more particularly, to the printhead portion of an inkjet printer. 
     Inkjet print cartridges operate by causing a small volume of ink to vaporize and be ejected from a firing chamber through one of a plurality of orifices so as to print a dot of ink on a recording medium such as paper. Typically, the orifices are arranged in one or more linear nozzle arrays. The properly sequenced ejection of ink from each orifice causes characters or other images to be printed in a swath across the paper. 
     An inkjet printhead generally includes ink channels to supply ink from an ink reservoir to each vaporization chamber (i.e., firing chamber) proximate to an orifice; a nozzle member in which the orifices are formed; and a silicon substrate containing a series of thin film resistors, one resistor per vaporization chamber. 
     To print a single dot of ink in a thermal inkjet printer, an electrical current from an external power supply is passed through a selected thin film resistor. The resistor is then heated, in turn superheating a thin layer of the adjacent ink within a vaporization chamber, causing explosive vaporization, and, consequently, causing a droplet of ink to be ejected through an associated orifice onto the paper. 
     In an inkjet printhead, described in U.S. Pat. No. 4,683,481 to Johnson, entitled “Thermal Ink Jet Common-Slotted Ink Feed Printhead,” ink is fed from an ink reservoir to the various vaporization chambers through an elongated hole formed in the substrate. The ink then flows to a manifold area, formed in a barrier layer between the substrate and a nozzle member, then into a plurality of ink channels, and finally into the various vaporization chambers. This design may be classified as a “center” feed design, with side electrical interconnects to a flex-circuit along the full length of the substrate. Ink is fed to the vaporization chambers from a central location then distributed outward into the vaporization chambers which contain the firing resistors. Some disadvantages of this type of ink feed design are that manufacturing time is required to make the hole in the substrate, and the required substrate area is increased by at least the area of the hole and also by extra substrate at both ends of the hole to provide structural integrity. Also, once the hole is formed, the substrate is relatively fragile, making handling more difficult. Such prior printhead design limited the ability of printheads to have compact stable substrates with wide swath high nozzle densities and the lower operating temperatures required for increased resolution and throughput. Print resolution depends on the density of ink-ejecting orifices and heating resistors formed on the cartridge printhead substrate. Modern circuit fabrication techniques allow the placement of substantial numbers of resistors on a single printhead substrate. However, the number of resistors applied to the substrate is limited by the number and location of the conductive components used to electrically connect the printhead to external driver circuitry in the printer unit. Specifically, an increasingly large number of firing resistors requires a correspondingly large number of interconnection pads, leads, grounds and the like. This increase in components and interconnects and the resulting increase in substrate size causes greater manufacturing/production costs, increases the probability that defects will occur during the manufacturing process, and increases the heat generated during high frequency operation. 
     BRIEF SUMMARY OF THE INVENTION 
     In order to solve the aforementioned problems, thermal inkjet printheads have been developed which efficiently incorporate pulse driver circuitry directly on the printhead substrate with the firing resistors. The incorporation of driver circuitry on the printhead substrate in this manner reduces the number of interconnect components needed to electrically connect the printhead to the printer unit. This results in improved production and operating efficiency. 
     To further produce high-efficiency integrated printing systems, significant research has developed improved transistor structures and unique methods for integrating them into high resolution compact substrates with good structural integrity and improved heat control characteristics. The integration of driver components, address lines, ground lines and firing resistors onto a common substrate is based on specialized, multi-layer connective circuitry so that the driver transistors can communicate with the firing resistors and other portions of the printing system. Typically, this connective circuitry involves a plurality of separate conductive layers. 
     To increase resolution and print quality, the printhead nozzles are placed closer together and are fed through an “edge feed” ink channel architecture. Both firing resistors and the associated orifices are placed closer together along the full length of the outer edges of the substrate, with the related circuitry primarily located in the middle portion of the substrate. To increase printer throughput, the width of the printing swath is increased by placing more nozzles on the print head to create a nozzle array which prints a one-half inch print swath. 
     More specifically, the invention contemplates a compact substrate of increased stability and structural integrity in order to achieve high resolution of 600 dots-per-inch in a nozzle array having a one-half inch swath. A plurality of ink vaporization chambers are respectively aligned with a total of three hundred nozzles in two longitudinal columns, one column extending longitudinally along one edge of the substrate and a second column extending longitudinally along an opposite edge of the substrate. Ink feed channels communicate through an ink passage from an underside of the substrate around both edges of the substrate to the vaporization channels. The ink feed channels have thereby been eliminated from the central portion of the substrate and replaced by the inkfeed channels at the edges of the substrate, so that structural stability is achieved without unduly extending both ends of the substrate. FIG. 14 is a view of one arrangement of orifices and the associated heater resistors on a printhead. 
    
    
     FIG. 1 is a perspective view of an inkjet print cartridge according to one embodiment of the present invention. 
     FIGS. 2A,  2 B, and  2 C provide a perspective view of an inkjet print cartridge according to one embodiment of the present invention. 
     FIG. 3 is a perspective view of an simplified schematic of the inkjet print cartridge of FIG. 1 for illustrative purposes. 
     FIG. 4 is a perspective view of the front surface of the Tape Automated Bonding (TAB) printhead assembly (hereinafter “TAB head assembly”) removed from the print cartridge of FIG.  3 . 
     FIG. 5 is a perspective view of the back surface of the TAB head assembly of FIG. 4 with a silicon substrate mounted thereon and the conductive leads attached to the substrate. 
     FIG. 6 is a side elevational view in cross-section taken along line A—A in FIG. 5 illustrating the attachment of conductive leads to electrodes on the silicon substrate. 
     FIG. 7 is a perspective view of the inkjet print cartridge of FIG. 1 with the TAB head assembly removed. 
     FIG. 8 is a perspective view of the headland area of the inkjet print cartridge of FIG. 7 FIG. 9 is a top plan view of the headland area of the inkjet print cartridge of FIG.  7 . 
     FIG. 10 is a perspective view of a portion of the inkjet print cartridge of FIG. 3 illustrating the configuration of a seal which is formed between the ink cartridge body and the TAB head assembly. 
     FIG. 11 is a top perspective view of a substrate structure containing heater resistors, ink channels, and vaporization chambers, which is mounted on the back of the TAB head assembly of FIG.  4 . 
     FIG. 12 is a top perspective view, partially cut away, of a portion of the TAB head assembly showing the relationship of an orifice with respect to a vaporization chamber heater resistor, and an edge of the substrate. 
     FIG. 13 is a schematic cross-sectional view taken along line B—B of FIG. 10 showing the adhesive seal between the TAB head assembly and the print cartridge as well as the ink flow path around the edges of the substrate. 
     FIG. 14 is a view of one arrangement of orifices and the associated heater resistors on a printhead. 
     FIG. 15 is a schematic diagram of one heater resistor and its associated address line, drive transistor, primitive select line and ground line. 
     FIG. 16 is a schematic diagram of the firing sequence for the address select lines when the printer carriage is moving from left to right. 
     FIG. 17 is a diagram showing the layout of the contact pads on the TAB head assemble. 
     FIG. 18 is a magnified perspective view showing a THA mounted on a print cartridge. 
     FIG. 19 shows one end of a substrate with firing resistors #1 and #2, with the interconnects identified. 
     FIG. 20 shows the opposite end of the substrate of FIG. 19, with firing resistors #299 and #300, with the interconnects identified. 
     FIG. 21 shows the substrate schematics and data taken in a direction along the width of the substrate. 
     FIG. 22 shows the substrate schematics and data taken in a direction along the length of the substrate. 
     FIG. 23 shows a silicon wafer prior to the individual dies being cut and separated from the wafer. 
     FIG. 24 shows the schematic and data for cutting a silicon wafer into individual dies. 
     FIG. 25 shows a typical inkjet printer which can incorporate the printhead of the present invention; 
     FIG. 26 shows a carriage having removable multi-color print cartridges, which can incorporated the printhead of the present invention; 
     FIG. 27 is a fragmentary view of the flex-circuit interconnect on a carriage with the interior carriage walls cut away; 
     FIG. 28 is a schematic block diagram of the presently preferred printer embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Generally speaking the invention provides an improved ink delivery system between an ink reservoir and ink ejection chambers in an inkjet printhead operating at high firing frequencies. In a preferred embodiment, a barrier layer containing ink channels and vaporization chambers is located between a rectangular substrate and a nozzle member containing an array of orifices. The substrate contains two linear arrays of heater elements, and each orifice in the nozzle member is associated with a vaporization chamber and heater element. The ink channels in the barrier layer have ink entrances generally running along two opposite edges of the substrate so that ink flowing around the edges of the substrate gain access to the ink channels and to the vaporization chambers. Piezoelectric elements can be used instead of heater elements. 
     More particularly, the features of the invention include an ink delivery system for an array of nozzle orifices in a print cartridge comprising an ink reservoir; a substrate having a plurality of individual ink firing chambers with an ink firing element in each chamber; an ink channel connecting said reservoir with said ink firing chambers, said channel including a primary channel connected at a first end with said reservoir and at a second end to a secondary channel; a separate inlet passage for each firing chamber connecting said secondary channel with said firing chamber for allowing high frequency refill of the firing chamber; a group of said firing chambers in adjacent relationship forming a primitive in which only one firing chamber in said primitive is activated at a time; first circuit means on said substrate connected to said firing elements; and second circuit means on said cartridge connected to said first circuit means, for transmitting firing signals to said ink firing elements at a frequency greater than 9 kHz. 
     Referring to FIG. 1, reference numeral  10  generally indicates an inkjet print cartridge incorporating a printhead according to one embodiment of the present invention simplified for illustrative purposes. The inkjet print cartridge  10  includes an ink reservoir  12  and a printhead  14 , where the printhead  14  is formed using Tape Automated Bonding (TAB). The printhead  14  (hereinafter “TAB head assembly  14  ”) includes a nozzle member  16  comprising two parallel columns of offset holes or orifices  17  formed in a flexible polymer flexible circuit  18  by, for example, laser ablation. 
     A back surface of the flexible circuit  18  includes conductive traces  36  formed thereon using a conventional photolithographic etching and/or plating process. These conductive traces  36  are terminated by large contact pads  20  designed to interconnect with a printer. The print cartridge  10  is designed to be installed in a printer so that the contact pads  20 , on the front surface of the flexible circuit  18 , contact printer electrodes providing externally generated energization signals to the printhead. 
     Windows  22  and  24  extend through the flexible circuit  18  and are used to facilitate bonding of the other ends of the conductive traces  36  to electrodes on a silicon substrate containing heater resistors. The windows  22  and  24  are filled with an encapsulant to protect any underlying portion of the traces and substrate. 
     In the print cartridge  10  of FIG. 1, the flexible circuit  18  is bent over the back edge of the print cartridge “snout” and extends approximately one half the length of the back wall  25  of the snout. This flap portion of the flexible circuit  18  is needed for the routing of conductive traces  36  which are connected to the substrate electrodes through the far end window  22 . The contact pads  20  are located on the flexible circuit  18  which is secured to this wall and the conductive traces  36  are routed over the bend and are connected to the substrate electrodes through the windows  22 ,  24  in the flexible circuit  18 . 
     FIGS. 2A,  2 B and  2 C show a front view of the TAB head assembly  14  of FIG. 1 removed from the print cartridge  10  and prior to windows  22  and  24  in the TAB head assembly  14  being filled with an encapsulant. TAB head assembly  14  has affixed to the back of the flexible circuit  18  a silicon substrate  28  (not shown) containing a plurality of individually energizable thin film resistors. Each resistor is located generally behind a single orifice  17  and acts as an ohmic heater when selectively energized by one or more pulses applied sequentially or simultaneously to one or more of the contact pads  20 . 
     The orifices  17  and conductive traces  36  may be of any size, number, and pattern, and the various figures are designed to simply and clearly show the features of the invention. The relative dimensions of the various features have been greatly adjusted for the sake of clarity. 
     The orifice  17  pattern on the flexible circuit  18  shown in FIG. 2 may be formed by a masking process in combination with a laser or other etching means in a step-and-repeat process, which would be readily understood by one of ordinary skilled in the art after reading this disclosure. FIG. 14, to be described in detail later, provides additional details of this process. Further details regarding TAB head assembly  14  and flexible circuit  18  are provided below. 
     FIG. 3 is a perspective view of a simplified schematic of the inkjet print cartridge of FIG. 1 for illustrative purposes. FIG. 4 is a perspective view of the front surface of the Tape Automated Bonding (TAB) printhead assembly (hereinafter “TAB head assembly”) removed from the simplified schematic print cartridge of FIG.  3 . 
     FIG. 5 shows the back surface of the TAB head assembly  14  of FIG. 4 showing the silicon die or substrate  28  mounted to the back of the flexible circuit  18  and also showing one edge of the barrier layer  30  formed on the substrate  28  containing ink channels and vaporization chambers. FIG. 7 shows greater detail of this barrier layer  30  and will be discussed later. Shown along the edge of the barrier layer  30  are the entrances to the ink channels  32  which receive ink from the ink reservoir  12 . The conductive traces  36  formed on the back of the flexible circuit  18  terminate in contact pads  20  (shown in FIG. 4) on the opposite side of the flexible circuit  18 . The windows  22  and  24  allow access to the ends of the conductive traces  36  and the substrate electrodes  40  (shown in FIG. 6) from the other side of the flexible circuit  18  to facilitate bonding. 
     FIG. 6 shows a side view cross-section taken along line A—A in FIG. 5 illustrating the connection of the ends of the conductive traces  36  to the electrodes  40  formed on the substrate  28 . As seen in FIG. 6, a portion  42  of the barrier layer  30  is used to insulate the ends of the conductive traces  36  from the substrate  28 . Also shown in FIG. 6 is a side view of the flexible circuit  18 , the barrier layer  30 , the windows  22  and  24 , and the entrances of the various ink channels  32 . Droplets of ink  46  are shown being ejected from orifice holes associated with each of the ink channels  32 . 
     FIG. 7 shows the print cartridge  10  of FIG. 1 with the TAB head assembly  14  removed to reveal the headland pattern  50  used in providing a seal between the TAB head assembly  14  and the printhead body. FIG. 8 shows the headland area in enlarged perspective view. FIG. 9 shows the headland area in an enlarged top plan view. The headland characteristics are exaggerated for clarity. Shown in FIGS. 8 and 9 is a central slot  52  in the print cartridge  10  for allowing ink from the ink reservoir  12  to flow to the back surface of the TAB head assembly  14 . 
     The headland pattern  50  formed on the print cartridge  10  is configured so that a bead of epoxy adhesive (not shown) dispensed on the inner raised walls  54  and across the wall openings  55  and  56  (so as to circumscribe the substrate when the TAB head assembly  14  is in place) will form an ink seal between the body of the print cartridge  10  and the back of the TAB head assembly  14  when the TAB head assembly  14  is pressed into place against the headland pattern  50 . Other adhesives which may be used include hot-melt, silicone, UV curable adhesive, and mixtures thereof. Further, a patterned adhesive film may be positioned on the headland, as opposed to dispensing a bead of adhesive. 
     When the TAB head assembly  14  of FIG. 5 is properly positioned and pressed down on the headland pattern  50  in FIG. 8 after the adhesive (not shown) is dispensed, the two short ends of the substrate  28  will be supported by the surface portions  57  and  58  within the wall openings  55  arid  56 . Additional details regarding adhesive  90  are shown in FIG.  13 . The configuration of the headland pattern  50  is such that, when the substrate  28  is supported by the surface portions  57  and  58  and adjoining central peninsulas  57   a  and  58   a,  the back surface of the flexible circuit  18  will be slightly above the top of the raised walls  54  and approximately flush with the flat top surface  59  of the print cartridge  10 . As the TAB head assembly  14  is pressed down onto the headland  50 , the adhesive is squished down. From the top of the inner raised walls  54 , the adhesive overspills into the gutter or groove  53  between the inner raised walls  54  and the outer raised wall  60  and overspills somewhat toward the slot  52 . From the wall openings  55  and  56 , the adhesive squishes inwardly in the direction of slot  52  and squishes outwardly toward the outer raised wall  60 , which blocks further outward displacement of the adhesive. The outward displacement of the adhesive not only serves as an ink seal, but encapsulates the conductive traces in the vicinity of the headland  50  from underneath to protect the traces from ink. 
     FIG. 10 shows a portion of the completed print cartridge  10  of FIG. 3 illustrating, by cross-hatching, the location of the underlying adhesive  90  (not shown) which forms the seal between the TAB head assembly  14  and the body of the print cartridge  10 . In FIG. 10 the adhesive is located generally between the dashed lines surrounding the array of orifices  17 , where the outer dashed line  62  is slightly within the boundaries of the outer raised wall  60  in FIG. 7, and the inner dashed line  64  is slightly within the boundaries of the inner raised walls  54  in FIG.  7 . The adhesive is also shown being squished through the wall openings  55  and  56  (FIG. 7) to encapsulate the traces leading to electrodes on the substrate. A cross-section of this seal taken along line B—B in FIG. 10 is also shown in FIG. 13, to be discussed later. 
     This seal formed by the adhesive  90  circumscribing the substrate  28  allows ink to flow from slot  52  and around the sides of the substrate to the vaporization chambers formed in the barrier layer  30 , but will prevent ink from seeping out from under the TAB head assembly  14 . Thus, this adhesive seal  90  provides a strong mechanical coupling of the TAB head assembly  14  to the print cartridge  10 , provides a fluidic seal, and provides trace encapsulation. The adhesive seal is also easier to cure than prior art seals, and it is much easier to detect leaks between the print cartridge body and the printhead, since the sealant line is readily observable. Further details on adhesive seal  90  are shown in FIG.  13 . 
     FIG. 11 is a front perspective view of the silicon substrate  28  which is affixed to the back of the flexible circuit  18  in FIG. 5 to form the TAB head assembly  14 . Silicon substrate  28  has formed on it, using conventional photolithographic techniques, two rows or columns of thin film resistors  70 , shown in FIG. 11 exposed through the vaporization chambers  72  formed in the barrier layer  30 . 
     In one embodiment, the substrate  28  is approximately one-half inch long and contains 300 heater resistors  70 , thus enabling a resolution of 600 dots per inch. Heater resistors  70  may instead be any other type of ink ejection element, such as a piezoelectric pump-type element or any other conventional element. Thus, element  70  in all the various figures may be considered to be piezoelectric elements in an alternative embodiment without affecting the operation of the printhead. Also formed on the substrate  28  are electrodes  74  for connection to the conductive traces  36  (shown by dashed lines) formed on the back of the flexible circuit  18 . 
     A demultiplexer  78 , shown by a dashed outline in FIG. 11, is also formed on the substrate  28  for demultiplexing the incoming multiplexed signals applied to the electrodes  74  and distributing the signals to the various thin film resistors  70 . The demultiplexer  78  enables the use of much fewer electrodes  74  than thin film resistors  70 . Having fewer electrodes allows all connections to the substrate to be made from the short end portions of the substrate, as shown in FIG. 4, so that these connections will not interfere with the ink flow around the long sides of the substrate. The demultiplexer  78  may be any decoder for decoding encoded signals applied to the electrodes  74 . The demultiplexer has input leads (not shown for simplicity) connected to the electrodes  74  and has output leads (not shown) connected to the various resistors  70 . The demultiplexer  78  circuity is discussed in further detail below. 
     Also formed on the surface of the substrate  28  using conventional photolithographic techniques is the barrier layer  30 , which may be a layer of photoresist or some other polymer, in which is formed the vaporization chambers  72  and ink channels  80 . A portion  42  of the barrier layer  30  insulates the conductive traces  36  from the underlying substrate  28 , as previously discussed with respect to FIG.  4 . 
     In order to adhesively affix the top surface of the barrier layer  30  to the back surface of the flexible circuit  18  shown in FIG. 5, a thin adhesive layer  84  (not shown), such as an uncured layer of poly-isoprene photoresist, is applied to the top surface of the barrier layer  30 . A separate adhesive layer may not be necessary if the top of the barrier layer  30  can be otherwise made adhesive. The resulting substrate structure is then positioned with respect to the back surface of the flexible circuit  18  so as to align the resistors  70  with the orifices formed in the flexible circuit  18 . This alignment step also inherently aligns the electrodes  74  with the ends of the conductive traces  36 . The traces  36  are then bonded to the electrodes  74 . This alignment and bonding process is described in more detail later with respect to FIG.  14 . The aligned and bonded substrate/flexible circuit structure is then heated while applying pressure to cure the adhesive layer  84  and firmly affix the substrate structure to the back surface of the flexible circuit  18 . 
     FIG. 12 is an enlarged view of a single vaporization chamber  72 , thin film resistor  70 , and frustum shaped orifice  17  after the substrate structure of FIG. 11 is secured to the back of the flexible circuit  18  via the thin adhesive layer  84 . A side edge of the substrate  28  is shown as edge  86 . In operation, ink flows from the ink reservoir  12  around the side edge  86  of the substrate  28 , and into the ink channel  80  and associated vaporization chamber  72 , as shown by the arrow  88 . Upon energization of the thin film resistor  70 , a thin layer of the adjacent ink is superheated, causing explosive vaporization and, consequently, causing a droplet of ink to be ejected through the orifice  17 . The vaporization chamber  72  is then refilled by capillary action. 
     In a preferred embodiment, the barrier layer  30  is approximately 1 mils thick, the substrate  28  is approximately 20 mils thick, and the flexible circuit  18  is approximately 2 mils thick. 
     Shown in FIG. 13 is a side elevational view cross-section taken along line B—B in FIG. 10 showing a portion of the adhesive seal  90 , applied to the inner raised wall  54  and wall openings  55 ,  56 , surrounding the substrate  28  and showing the substrate  28  being adhesively secured to a central portion of the flexible circuit  18  by the thin adhesive layer  84  on the top surface of the barrier layer  30  containing the ink channels and vaporization chambers  92  and  94 . A portion of the plastic body of the printhead cartridge  10 , including raised walls  54  shown in FIGS. 7 and 8, is also shown. 
     FIG. 13 also illustrates how ink  88  from the ink reservoir  12  flows through the central slot  52  formed in the print cartridge  10  and flows around the edges  86  of the substrate  28  through ink channels  80  into the vaporization chambers  92  and  94 . Thin film resistors  96  and  98  are shown within the vaporization chambers  92  and  94 , respectively. When the resistors  96  and  98  are energized, the ink within the vaporization chambers  92  and  94  are ejected, as illustrated by the emitted drops of ink  101  and  102 . 
     The edge feed feature, where ink flows around the edges  86  of the substrate  28  and directly into ink channels  80 , has a number of advantages over previous center feed printhead designs which form an elongated central hole or slot running lengthwise in the substrate to allow ink to flow into a central manifold and ultimately to the entrances of ink channels. One advantage is that the substrate or die  28  width can be made narrower, due to the absence of the elongated central hole or slot in a central interior portion  29  of the substrate. Not only can the substrate be made narrower, but the length of the edge feed substrate can be shorter, for the same number of nozzles, than the center feed substrate due to the substrate structure now being less prone to cracking or breaking without the central ink feed hole. This shortening of a substrate die  210  (see FIG. 23) to form the substrate  28  enables a shorter headland  50  in FIG. 8 and, hence, a shorter print cartridge snout. This is important when the print cartridge  10  is installed in a printer which uses one or more pinch rollers below the snout&#39;s transport path across the paper to press the paper against the rotatable platen and which also uses one or more rollers (also called star wheels) above the transport path to maintain the paper contact around the platen. With a shorter print cartridge snout, the star wheels can be located closer to the pinch rollers to ensure better paper/roller contact along the transport path of the print cartridge snout. Additionally, by making the substrate smaller, more substrates can be formed per wafer, thus lowering the material cost per substrate. 
     Other advantages of the edge feed feature are that manufacturing time is saved by not having to etch a slot in the substrate, and the substrate is less prone to breakage during handling. Further, the substrate is able to dissipate more heat, since the ink flowing across the back of the substrate and around the edges of the substrate acts to draw heat away from the back of the substrate. 
     There are also a number of performance advantages to the edge feed design. Be eliminating the manifold as well as the slot in the substrate, the ink is able to flow more rapidly into the vaporization chambers, since there is less restriction on the ink flow. This more rapid ink flow improves the frequency response of the printhead, allowing higher printing rates from a given number of orifices. Further, the more rapid ink flow reduces crosstalk between nearby vaporization chambers caused by variations in ink flow as the heater elements in the vaporization chambers are fired. 
     In another embodiment, the ink reservoir contains two separate ink sources, each containing a different color of ink. In this alternative embodiment, the central slot  52  in FIG. 13 is bisected, as shown by the dashed line  103 , so that each side of the central slot  52  communicates with a separate ink source. Therefore, the left linear array of vaporization chambers can be made to eject one color of ink, while the right linear array of vaporization chambers can be made to eject a different color of ink. This concept can even be used to create a four color printhead, where a different ink reservoir feeds ink to ink channels along each of the four sides of the substrate. Thus, instead of the two-edge feed design discussed above, a four-edge design would be used, preferably using a square substrate for symmetry. 
     In order to make a finished printhead, the TAB head assembly is positioned on the print cartridge  10 , and the previously described adhesive seal  90  is formed to firmly secure the nozzle member to the print cartridge, provide an ink-proof seal around the substrate between the nozzle member and the ink reservoir, and encapsulate the traces in the vicinity of the headland so as to isolate the traces from the ink. Peripheral points on the flexible TAB head assembly are then secured to the plastic print cartridge  10  by a conventional melt-through type bonding process to cause the polymer flexible circuit  18  to remain relatively flush with the surface of the print cartridge  10 , as shown in FIG.  1 . 
     To increase resolution and print quality, the printhead nozzles must be placed closer together. This requires that both heater resistors and the associated orifices be placed closer together. Referring to FIG. 14, as discussed above, the orifices  17  in the nozzle member  16  of the TAB head assembly are generally arranged in two major columns of orifices  17  as shown in FIG.  14 . For clarity of understanding, the orifices  17  are conventionally assigned a number as shown, starting at the top right as the TAB head assembly as viewed from the external surface of the nozzle member  16  and ending in the lower left, thereby resulting in the odd numbers being arranged in one column and even numbers being arranged in the second column. Of course, other numbering conventions may be followed, but the description of the firing order of the orifices  17  associated with this numbering system has advantages. The orifices/resistors in each column are spaced {fraction (1/300)} of an inch apart in the long direction of the nozzle member. The orifices and resistors in one column are offset from the orifice/resistors in the other column in the long direction of the nozzle member by {fraction (1/600)} of an inch, thus, providing 600 dots per inch (dpi) printing. 
     In one embodiment of the present invention the orifices  17 , while aligned in two major columns as described, are further arranged in an offset pattern within each column to match the offset heater resistors  70  disposed in the substrate  28  as illustrated in FIG.  14 . Within a single row or column of resistors, a small offset E is provided between resistors. This small offset E allows adjacent resistors  70  to be fired at slightly different times when the TAB head assembly is scanning across the recording medium to further minimize cross-talk effects between adjacent vaporization chambers  130 . Thus, although the resistors are fired at twenty two different times, the offset allows the ejected ink drops from different nozzles to be placed in the same horizontal position on the print media. The resistors  70  are coupled to electrical drive circuitry (not shown in FIG. 14) and are organized in groups of fourteen primitives which consist of four primitives of twenty resistors (P 1 , P 2 , P 13  and P 14 ) and ten primitives of twenty two resistors for a total of 300 resistors. The fourteen resistor primitives (and associated orifices) are shown in FIG.  22 . 
     As described, the firing heater resistors  70  of the preferred embodiment are organized as fourteen primitive groups of twenty or twenty-two resistors. It can be seen that each resistor (numbered  1  through  300  and corresponding to the orifices  17  of FIG. 14) is controlled by its own FET drive transistor, which shares its control input Address Select (A 1 -A 22 ) with thirteen other resistors. Each resistor is tied to nineteen or twenty-one other resistors by a common node Primitive Select (PS 1 -PS 14 ). Consequently, firing a particular resistor requires applying a control voltage at its “Address Select” terminal and an electrical power source at its “Primitive Select” terminal. Only one Address Select line is enabled at one time. This ensures that the Primitive Select and Group Return lines supply current to at most one resistor at a time. Otherwise, the energy delivered to a heater resistor would be a function of the number of resistors  70  being fired at the same time. FIG. 15 is a schematic diagram of an individual heater resistor and its FET drive transistor. As shown in FIG. 15, Address Select and Primitive Select lines also contain transistors for draining unwanted electrostatic discharge and pull down resistors to place all unselected addresses in an off state. Table I shows the correlation between the firing resistor/orifice and the Address Select and Primitive Select Lines. 
     
       
         
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE I 
               
             
             
               
                   
               
               
                 Nozzle Number by Address Select and Primitive Select Lines 
               
             
          
           
               
                   
                 P1 
                 P2 
                 P3 
                 P4 
                 P5 
                 P6 
                 P7 
                 P8 
                 P9 
                 P10 
                 P11 
                 P12 
                 P13 
                 P14 
               
               
                   
                   
               
             
          
           
               
                 A1 
                 1 
                   
                 45 
                 42 
                 89 
                 86 
                 133 
                 130 
                 177 
                 174 
                 221 
                 21B 
                 265 
                 262 
               
               
                 A2 
                 7 
                 4 
                 51 
                 48 
                 95 
                 92 
                 139 
                 136 
                 183 
                 180 
                 227 
                 224 
                 271 
                 268 
               
               
                 A3 
                 13 
                 10 
                 57 
                 54 
                 101 
                 98 
                 145 
                 142 
                 129 
                 186 
                 233 
                 230 
                 277 
                 274 
               
               
                 A4 
                 19 
                 16 
                 63 
                 60 
                 107 
                 104 
                 151 
                 148 
                 195 
                 192 
                 239 
                 236 
                 283 
                 280 
               
               
                 A5 
                 25 
                 22 
                 63 
                 66 
                 113 
                 110 
                 157 
                 154 
                 201 
                 198 
                 245 
                 242 
                 289 
                 286 
               
               
                 A6 
                 31 
                 28 
                 75 
                 72 
                 119 
                 118 
                 163 
                 160 
                 207 
                 204 
                 251 
                 248 
                 295 
                 292 
               
               
                 A7 
                 37 
                 34 
                 81 
                 78 
                 125 
                 122 
                 169 
                 166 
                 213 
                 204 
                 257 
                 254 
                   
                 298 
               
               
                 A8 
                   
                 40 
                 43 
                 84 
                 87 
                 125 
                 131 
                 172 
                 175 
                 216 
                 219 
                 260 
                 263 
                   
               
               
                 A9 
                 5 
                 2 
                 49 
                 46 
                 93 
                 90 
                 137 
                 134 
                 181 
                 178 
                 225 
                 222 
                 269 
                 266 
               
               
                 A10 
                 11 
                 8 
                 55 
                 52 
                 99 
                 96 
                 143 
                 140 
                 187 
                 184 
                 231 
                 228 
                 275 
                 272 
               
               
                 A11 
                 17 
                 14 
                 61 
                 58 
                 105 
                 102 
                 149 
                 146 
                 193 
                 190 
                 237 
                 234 
                 281 
                 278 
               
               
                 A12 
                 23 
                 20 
                 67 
                 64 
                 111 
                 108 
                 155 
                 152 
                 199 
                 196 
                 243 
                 240 
                 287 
                 284 
               
               
                 A13 
                 29 
                 26 
                 73 
                 70 
                 117 
                 114 
                 161 
                 158 
                 205 
                 202 
                 249 
                 246 
                 293 
                 290 
               
               
                 A14 
                 35 
                 32 
                 79 
                 76 
                 123 
                 120 
                 167 
                 164 
                 211 
                 208 
                 255 
                 252 
                 299 
                 296 
               
               
                 A15 
                   
                 38 
                 41 
                 82 
                 85 
                 126 
                 129 
                 170 
                 173 
                 214 
                 217 
                 258 
                 261 
                   
               
               
                 A16 
                 3 
                   
                 47 
                 44 
                 91 
                 88 
                 135 
                 132 
                 179 
                 176 
                 223 
                 220 
                 267 
                 264 
               
               
                 A17 
                 9 
                 6 
                 53 
                 50 
                 97 
                 94 
                 141 
                 138 
                 185 
                 182 
                 229 
                 226 
                 273 
                 270 
               
               
                 A18 
                 15 
                 12 
                 59 
                 56 
                 103 
                 100 
                 147 
                 144 
                 191 
                 188 
                 235 
                 232 
                 279 
                 276 
               
               
                 A19 
                 21 
                 18 
                 65 
                 62 
                 109 
                 106 
                 153 
                 150 
                 197 
                 194 
                 241 
                 238 
                 285 
                 282 
               
               
                 A20 
                 27 
                 24 
                 71 
                 68 
                 115 
                 112 
                 159 
                 156 
                 203 
                 200 
                 247 
                 244 
                 291 
                 288 
               
               
                 A21 
                 33 
                 30 
                 77 
                 74 
                 121 
                 118 
                 165 
                 162 
                 209 
                 206 
                 253 
                 250 
                 297 
                 294 
               
               
                 A22 
                 39 
                 36 
                 83 
                 80 
                 127 
                 124 
                 171 
                 168 
                 215 
                 212 
                 259 
                 256 
                   
                 300 
               
               
                   
               
             
          
         
       
     
     The Address Select lines are sequentially turned on via TAB head assembly interface circuitry according to a firing order counter located in the printer and sequenced (independently of the data directing which resistor is to be energized) from A 1  to A 22  when printing form left to right and from A 22  to A 1  when printing from right to left. The print data retrieved from the printer memory turns on any combination of the Primitive Select lines. Primitive Select lines (instead of Address Select lines) are used in the preferred embodiment to control the pulse width. Disabling Address Select lines while the drive transistors are conducting high current can cause avalanche breakdown and consequent physical damage to MOS transistors. Accordingly, the Address Select lines are “set” before power is applied to the Primitive Select lines, and conversely, power is turned off before the Address Select lines are changed. 
     In response to print commands from the printer, each primitive is selectively fired by powering the associated primitive select interconnection. To provide uniform energy per heater resistor only one resistor is energized at a time per primitive. However, any number of the primitive selects may be enabled concurrently. Each enabled primitive select thus delivers both power and one of the enable signals to the driver transistor. The other enable signal is an address signal provided by each address select line only one of which is active at a time. Each address select line is tied to all of the switching transistors so that all such switching devices are conductive when the interconnection is enabled. Where a primitive select interconnection and an address select line for a heater resistor are both active simultaneously, that particular heater resistor is energized. Thus, firing a particular resistor requires applying a control voltage at its “Address Select” terminal and an electrical power source at its “Primitive Select” terminal. Only one Address Select line is enabled at one time. This ensures that the Primitive Select and Group Return lines supply current to at most one resistor at a time. Otherwise, the energy delivered to a heater resistor would be a function of the number of resistors  70  being fired at the same time. FIG. 16 shows the firing sequence when the print carriage is scanning from left to right. The firing sequence is reversed when scanning from right to left. The resistor firing frequency is shown as F in FIG. 16. A brief rest period of approximately ten percent of the period, 1/F is allowed between cycles. This rest period prevents Address Select cycles from overlapping due to printer carriage velocity variations. 
     The interconnections for controlling the TAB head assembly driver circuitry include separate primitive select and primitive common interconnections. The driver circuity of the preferred embodiment comprises an array of fourteen primitives, fourteen primitive commons, and twenty-two address select lines, thus requiring 50 interconnections to control 300 firing resistors. The integration of both heater resistors and FET driver transistors onto a common substrate creates the need for additional layers of conductive circuitry on the substrate so that the transistors could be electrically connected to the resistors and other components of the system. This creates a concentration of heat generation within the substrate. 
     Referring to FIGS. 1 and 2, the print cartridge  10  is designed to be installed in a printer so that the contact pads  20 , on the front surface of the flexible circuit  18 , contact printer electrodes which couple externally generated energization signals to the TAB head assembly. To access the traces  36  on the back surface of the flexible circuit  18  from the front surface of the flexible circuit, holes (vias) are formed through the front surface of the flexible circuit to expose the ends of the traces. The exposed ends of the traces are then plated with, for example, gold to form the contact pads  20  shown on the front surface of the flexible circuit in FIG.  2 . In the preferred embodiment, the contact or interface pads  20  are assigned the functions listed in Table II. FIG. 17 shows the location of the interface pads  20  on the TAB head assembly of FIG.  2 . 
     
       
         
               
             
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 11 
               
             
             
               
                   
               
               
                 ELECTRICAL PAD DEFINITON 
               
             
          
           
               
                 Odd Side of Head 
                 Even Side of Head 
               
             
          
           
               
                 Pad# 
                 Name 
                 Function 
                 Pad# 
                 Name 
                 Function 
               
               
                   
               
             
          
           
               
                 1 
                 A9 
                 Address Select 9 
                 2 
                 G6 
                 Common 6 
               
               
                 3 
                 PS7 
                 Primitive Select 7 
                 4 
                 PS6 
                 Primitive Select 6 
               
               
                 5 
                 G7 
                 Common 7 
                 6 
                 A11 
                 Address Select 11 
               
               
                 7 
                 PS5 
                 Primitive Select 5 
                 8 
                 A13 
                 Address Select 13 
               
               
                 9 
                 G5 
                 Common 5 
                 10 
                 G4 
                 Common 4 
               
               
                 11 
                 G3 
                 Common 3 
                 12 
                 PS4 
                 Primitive Select 4 
               
               
                 13 
                 PS3 
                 Primitive Select 3 
                 14 
                 A15 
                 Address Select 15 
               
               
                 15 
                 A7 
                 Address Select 7 
                 16 
                 A17 
                 Address Select 17 
               
               
                 17 
                 A5 
                 Address Select 5 
                 18 
                 G2 
                 Common 2 
               
               
                 19 
                 G1 
                 Common 1 
                 20 
                 PS2 
                 Primitive Select 2 
               
               
                 21 
                 PS1 
                 Primitive Select 1 
                 22 
                 A19 
                 Address Select 19 
               
               
                 23 
                 A3 
                 Address Select 3 
                 24 
                 A21 
                 Address Select 21 
               
               
                 25 
                 A1 
                 Address Select 1 
                 26 
                 A22 
                 Address Select 22 
               
               
                 27 
                 TSR 
                 Thermal Sense 
                 28 
                 R10X 
                 10X Resistor 
               
               
                 29 
                 A2 
                 Address Select 2 
                 30 
                 A20 
                 Address Select 20 
               
               
                 31 
                 A4 
                 Address Select 4 
                 32 
                 PS14 
                 Primitive Select 14 
               
               
                 33 
                 PS13 
                 Primitive Select 13 
                 34 
                 G14 
                 Common 14 
               
               
                 35 
                 G13 
                 Common 13 
                 36 
                 A18 
                 Address Select 18 
               
               
                 37 
                 A6 
                 Address Select 6 
                 38 
                 A16 
                 Address Select 16 
               
               
                 39 
                 A8 
                 Address Select 8 
                 40 
                 PS12 
                 Primitive Select 12 
               
               
                 41 
                 PS11 
                 Primitive Select 11 
                 42 
                 G12 
                 Common 12 
               
               
                 43 
                 G11 
                 Common 11 
                 44 
                 G10 
                 Common 10 
               
               
                 45 
                 A10 
                 Address Select 10 
                 46 
                 PS10 
                 Primitive Select 10 
               
               
                 47 
                 A12 
                 Address Select 12 
                 48 
                 G8 
                 Common 8 
               
               
                 49 
                 PS9 
                 Primitive Select 9 
                 50 
                 P58 
                 Primitive Select 8 
               
               
                 51 
                 G9 
                 Common 9 
                 52 
                 A14 
                 Address Select 14 
               
               
                   
               
             
          
         
       
     
     FIG. 18 shows the relative positions of the even # nozzles  2  through  300  and the odd # nozzles  1  through  299  when the THA is mounted on a print cartridge. 
     FIGS. 19-20 are an enlarged illustration of both truncated end portions  202 ,  204  of the substrate showing the ESD devices  206  and the interconnect junctions  208 . 
     FIGS. 21-22 includes schematic drawings as well as related data tables showing the dimensions, electrical resistance and identification of the various circuitry portions of the substrate. It will be appreciated by those skilled in the art that substantial heat is generated by all of the circuitry on the substrate. More particularly, each firing resistor requires 300 milliamps whenever it is selected for firing. For a 12 KHertz firing frequency of F, and in reference to the firing diagram of FIG. 16, when all of the twenty-two address lines are activated in a duty cycle with each pulse width being 2.3 microseconds, then 2.3×22 equals a result divided by 83 microseconds to create a 61% duty cycle. Therefore it is possible when all primitives are firing at the same time to pass a current of approximately 25 amps through the substrate (300 milliamps×14×0.61). The cooling characteristices of the edge feed design are therefore very helpful in avoiding the overheating of the substrate during normal operation. 
     Also, in the present design it was the required width of the interconnects which determined the maximum width of the substrate, thereby making the multiplexing on the substrate very important in order to provide only 52 interconnects to selectively actuate 300 firing resistors in the vaporization compartments. 
     FIGS. 23-24 show the dimensions for cutting a silicon wafer in order to obtain a high yield for the substrate dies of the present invention. Although some of the dies such as  210  which extend into the 5 mm wide exclusion zone  212  are not usable if critical components of the multilayer substrate lie inside such exclusion zone, nevertheless the invention still provides significantly better yield than for an estimated yield for a center feed ink channel design having the same  300  nozzle 600 dpi specifications as the presently preferred embodiment of the present invention. 
     In the presently preferred embodiment of the invention disclosed herein, we have combined a 600 dpi ½ inch swath black pen with three 300 dpi color pens each generating a swath of approximately ⅓ inch. The high performance black pen is typically used for printing text and other “black only” features, and thus the output quality and throughput of these features is greater. It also improves the output quality of color graphics and color features by teaming with the three lower performance color pens when printing color graphics or color features. The black component of the graphics which is often a large portion of color graphics content is at a higher resolution and thus at a higher output quality level. The larger swath can then be combined with printing algorithms to improve the throughput of color graphics. 
     Even though the invention can be used in any printing environment where text and/or graphics are applied to media using monochrome and/or color comoponents, the presently preferred embodiment of the invention is used in an inkjet printer of the type shown in FIG.  25 . In particular, inkjet printer  110  includes an input tray  112  containing sheets of media  114  which pass through a print zone, and are fed past an exit  118  into an output tray  116 . Referring to FIGS. 25-26, a movable carriage  120  holds print cartridges  122 ,  124 ,  126 , and  128  which respectively hold yellow (Y), magenta (M), cyan (C) and black (K) inks. The front of the carriage has a support bumper  130  which rides along a guide  132  while the back of the carriage has multiple bushings such as  34  which ride along slide rod  136 . The position of the carriage as it traverses back and forth across the media is determined from an encoder strip  138  in order to be sure that the various ink nozzles on each print cartridge are selectively fired at the appropriate time during a carriage scan. 
     Referring to FIGS. 26-27, a 300 dpi color inkjet cartridge  140  having a tab-circuit with a four column thirty-two pad electrical interconnect  142  is removably installed in three chutes  144 ,  146 ,  148  of a unitary carriage  150 . A flex-circuit member  52  having three matching sets of conductive pads  54 ,  56 ,  58  is mounted on flex-frame pins  160  for operative engagement with the cartridge pads when the cartridge is inserted into its appropriate chute. An enlarged set of conductive pads  162  covering a larger area, having a different layout, and constituting an array of six columns totaling fifty-two conductive pads on the flex-circuit member is designed for operative engagement with cartridge pads on a 600 dpi black injet cartridge  164 . 
     FIG. 28 shows the preferred mounting relationship between a 300 dpi nozzle array  196  of the color printheads and a 600 dpi nozzle array  198  of the black printhead. Control circuitry  199  on the substrate enables the three hundred firing resistors of the black printhead to be controlled through fifty-two electrical interconnect jpads, and similary enables all one hundred four firing resistors of each color printhead to be controlled through thirty-two electrical interconnect pads. 
     This invention allows higher resolution and speed to occur for frequently printed features such as text and the most frequent color components of graphics such as black. Thus by printing these frequent features and components faster and at a higher resolution, the entire page is faster and of higher quality and is more comprable with laser printing performance (8+pages per minute) and laser printing quality (600 dpi resolution). 
     While specific illustrated embodiments have been shown and described, it will be appreciated by those skilled in the art that various modifications, changes and additions can be made to the methods, structures and apparatus of the invention without departing from the spirit and scope of the invention as set forth in the following claims.