Abstract:
Disclosed is a printhead including a substrate having a plurality of fluid heating elements. First, second and third fluid channels deliver fluid to the plurality of fluid heating elements. Each of the first, second and third fluid channels is operatively associated with first, second and third multiplicity&#39;s, respectively, of fluid heating elements of the plurality of fluid heating elements. The first and second fluid channels are defined by first and second edges, respectfully, of the substrate. The third fluid channel is defined by a slot extending through the substrate. The first, second and third fluid channels can each deliver a different color ink to their respective fluid heating elements.

Description:
TECHNICAL FIELD  
         [0001]    This invention relates generally to inkjet printing systems. In particular, the present invention is an inkjet printhead that delivers ink to firing resistors positioned within the printhead die using both slotted and edgefeed ink delivery systems. Using both slotted and edgefeed ink delivery systems permits an overall reduction in the size of the printhead die while maintaining the same number of firing resistors or allows more firing resistors to be included in the same printhead die size.  
         BACKGROUND OF THE INVENTION  
         [0002]    Throughout the business world, inkjet printing systems are extensively used for image reproduction. Inkjet printing systems frequently make use of an inkjet printhead mounted within a carriage that is moved back and forth across print media, such as paper. As the printhead is moved across the print media, a control system activates the printhead to deposit or eject ink droplets onto the print media to form images and text. Such systems may be used in a wide variety of applications, including computer printers, plotters, copiers and facsimile machines.  
           [0003]    Ink is provided to the printhead by a supply of ink that is either carried by the carriage or mounted to the printing system such that the supply of ink does not move with the carriage. For the case where the ink supply is not carried with the carriage, the ink supply can be in fluid communication with the printhead to replenish the printhead or the printhead can be intermittently connected with the ink supply by positioning the printhead proximate to a filling station to which the ink supply is connected whereupon the printhead is replenished with ink from the refilling station.  
           [0004]    For the case where the ink supply is carried with the carriage, the ink supply may be integral with the printhead whereupon the entire printhead and ink supply is replaced when ink is exhausted. Alternatively, the ink supply can be carried with the carriage and be separately replaceable from the printhead.  
           [0005]    For convenience, the concepts of the invention are discussed in the context of thermal inkjet printheads. A thermal inkjet printhead die includes an array of firing chambers having orifices (also called nozzles) which face the print media. The ink is applied to individually addressable ink energizing elements (such as firing resistors) within the firing chambers. Energy provided by the firing resistors heats the ink within the firing chambers causing the ink to bubble. This in turn causes the ink to be expelled out of the orifice of the firing chamber toward the print media. As the ink is expelled, the bubble collapses and more ink is drawn into the firing chambers, allowing for repetition of the ink expulsion process.  
           [0006]    Inkjet printhead dies are in part manufactured using processes that employ photolithographic techniques similar to those used in semiconductor manufacturing. The components are constructed on a flat substrate layer of silicon by selectively adding layers of various materials and subtracting portions of the substrate layer and added layers using these photolithographic techniques. Some existing inkjet printhead dies are defined by a silicon substrate layer having firing resistors within a stack of thin film layers, a barrier layer and an orifice layer or orifice plate. Material removed from the barrier layer defines the firing chambers, while openings within the orifice layer or plate define the nozzles for the firing chambers.  
           [0007]    In an inkjet printhead die, ink is delivered to the firing chambers and thereby the firing resistors by either a slotted ink delivery system or an edgefeed ink delivery system. In a slotted ink delivery system, the inkjet printhead die includes one or more slots that route ink from a backside of the printhead die to a front side where the firing resistors reside on at least one side of each of the slots. Typically, a single color printhead die includes a single ink delivery slot with one column of firing resistors on each side of the slot. However, a single color printhead die may include multiple slots to improve print quality and/or speed. A multicolor printhead die typically includes an ink delivery slot for each color. Generally, the printhead die is mounted to a printhead cartridge body using a structural adhesive. In multicolor print cartridges having a printhead die with multiple slots, this structural adhesive is deposited in a loop around each individual slot to separate out the individual ink colors.  
           [0008]    Although this slotted ink delivery system for inkjet printhead dies adequately delivers ink the firing resistors, there are some disadvantages to this system of ink routing. The primary disadvantages are strength, size and waste. With regard to strength, in a printhead die, the ink delivery slot(s) structurally weaken the printhead die. As such, the greater the number of slots the weaker the die. With regard to size, the ink delivery slots can only be put so close together before manufacturability issues arise that causes manufacture of the printhead die to be accomplished in less than an optimal cost efficient manner. As such, the spacing of the ink delivery slots limits how small the printhead die can be. With regard to waste, approximately 300 μm of printhead die material (i.e. silicon) is lost by creating a slot. As such, the greater the number of slots, the greater the waste.  
           [0009]    In an edgefeed ink delivery system, ink is routed from a backside of the printhead die, then around the edges of the die to a front side of the die where the firing resistors reside. Typically in an edgefeed ink delivery system, only the two long edges of the printhead die are used for ink feed, while the two short edges of the die are used for electrical connections. As such, the typical edgefeed printhead die includes only a single column of firing resistors adjacent each long edge. Since there are only two edges for ink flow, an edgefeed printhead die is limited to a maximum of two color inkjet printing, while in practice, the use of an edgefeed printhead die is almost exclusively used for single color printing. Generally, the orifice plate of the printhead die is oversized to permit mounting of the printhead die to a printhead cartridge body using a structural adhesive.  
           [0010]    The edgefeed ink delivery system for inkjet printhead dies adequately delivers ink to the firing resistors. Moreover, edgefeed printhead dies have a large strength and utility advantage over slotted printhead dies because unlike slotted dies there are no ink delivery slots in an edgefeed die to weaken the die or cause waste. In addition, edgefeed printhead dies have a size advantage over slotted dies because the absence of ink delivery slots allows the edgefeed die to be made smaller. However, there is a disadvantage to the edgefeed die when compared to the slotted die, since the edgefeed die is limited to a maximum of two color printing while that slotted die can print as many colors as there are slots.  
           [0011]    Typically to obtain print quality and speed, it is to necessary to maximize the density of the firing chambers (i.e. firing resistors) and/or increase the number of firing chambers. Maximizing the density of the firing chambers and/or increasing the number of firing chambers typically necessitates an increase in the size of the printhead die and/or a miniaturization of printhead die components. As discussed above, when the density is sufficiently high, conventional manufacturing by assembling separately produced components becomes more difficult and costly. In addition, the substrate that supports firing resistors, the barrier that isolates individual resistors, and the orifice plate that provides a nozzle above each resistor are all subject to small dimensional variations that can accumulate to limit miniaturization. Further, the assembly of such components for conventional printheads requires precision that limits manufacturing efficiency.  
           [0012]    As such, there is a desire for a multicolor printhead die that is economical to manufacture, and relatively simple to incorporate into inkjet printhead cartridges usable in thermal inkjet printing systems.  
         SUMMARY OF THE INVENTION  
         [0013]    The present invention is a printhead. The printhead comprises a substrate that includes a plurality of fluid heating elements. A plurality of fluid channels deliver fluid to the plurality of fluid heating elements. The plurality of fluid channels includes at least one edgefeed fluid channel and at least one slot feed fluid channel.  
           [0014]    In one aspect of the present invention, the plurality of fluid channels includes first, second and third fluid channels. The first fluid channel is operatively associated with a first multiplicity of fluid heating elements of the plurality of fluid heating elements, with the first fluid channel being defined by a first edge of the substrate. The second fluid channel is operatively associated with a second multiplicity of fluid heating elements of the plurality of fluid heating elements, with the second fluid channel being defined by a second edge of the substrate. The third fluid channel is operatively associated with a third multiplicity of fluid heating elements of the plurality of fluid heating elements, with the third fluid channel being defined by a slot extending through the substrate. In a further aspect of the present invention, the first fluid channel delivers ink of a first color to the first multiplicity of fluid heating elements, the second fluid channel delivers ink of a second color to the second multiplicity of fluid heating elements, and the third fluid channel delivers ink of a third color to the third multiplicity of fluid heating elements. In still a further aspect of the present invention, the first, second and third fluid channels deliver ink of the same color to the first, second and third multiplicity&#39;s of fluid heating elements.  
           [0015]    In another embodiment, the present invention provides a printhead cartridge for a printing system having a fluid supply for supplying fluid to the printhead cartridge. The printhead cartridge includes a cartridge body, and a printhead die mounted to the cartridge body. The printhead die includes a plurality of firing resistors. A plurality of fluid channels deliver fluid to the plurality of firing resistors. The plurality of fluid channels includes at least one edgefeed fluid channel and at least on slot feed fluid channel.  
           [0016]    In a further embodiment, the present invention provides a fluid delivery system that comprises a substrate including a plurality of fluid heating elements. The substrate includes an edgefeed fluid delivery feature for delivering fluid to the plurality of fluid heating elements, and a slot feed fluid delivery feature for delivering fluid to the plurality of fluid heating elements.  
           [0017]    In still another embodiment, the present invention provides a printhead comprising a substrate that includes first, second, third and fourth rows of firing resistors. The substrate also includes a single slot feed fluid delivery channel for delivering fluid to at least the first row of firing resistors, and at least one edgefeed fluid delivery channel for delivering fluid to at least the second row of firing resistors.  
           [0018]    In still a further embodiment, the present invention provides a method of delivering fluid comprising the steps of providing a substrate having a plurality of fluid heating elements, delivering fluid via an edgefeed fluid delivery feature of the substrate to the plurality of fluid heating elements, and delivering fluid via a slot feed fluid delivery feature of the substrate to the plurality of fluid heating elements.  
           [0019]    This printhead die substantially minimizes the size, strength and waste issues associated with present slotted printhead dies. In particular, the first, second and third fluid channels of the printhead die of the present invention permits three color printing with a printhead die having only a single slot as compared to the three slots needed for three color printing in a typical slotted printhead die. The elimination of two slots allows the printhead die of the present invention to exhibit an overall size reduction, as well as an increase in strength and a reduction in waste. In addition, the printhead die of the present invention substantially eliminates the single ink color or two ink color limitations of typical edgefeed printhead dies. Moreover, the printhead die of the present invention provides the above features throughout the useful life of the printhead cartridge to which the printhead die is mounted so as to preclude premature replacement of the printhead cartridge and the associated cost. Lastly, the printhead die of the present invention is relatively easy and inexpensive to manufacture, and is relatively simple to incorporate into printhead cartridges used in thermal inkjet printing systems. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    The accompanying drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification. The drawings illustrate the embodiments of the present invention and together with the description serve to explain the principals of the invention. Other embodiments of the present invention and many of the intended advantages of the present invention will be readily appreciated as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings, in which like reference numerals designate like parts throughout the figures thereof, and wherein:  
         [0021]    [0021]FIG. 1 is a perspective view of a thermal inkjet printing system with a cover opened to show a plurality of replaceable ink containers and a plurality of replaceable inkjet printhead cartridges incorporating inkjet printhead dies in accordance with the present invention.  
         [0022]    [0022]FIG. 2 is a perspective view a portion of a scanning carriage showing the replaceable ink containers positioned in a receiving station that provides fluid communication between the replaceable ink containers and one or more printhead cartridges incorporating inkjet printhead dies in accordance with the present invention.  
         [0023]    [0023]FIG. 3 is a partial sectional view of the inkjet printhead die in accordance with the present invention shown mounted to a multicolor inkjet printhead cartridge of FIG. 1.  
         [0024]    [0024]FIG. 4 is an enlarged plan view of the inkjet printhead die shown in FIG. 3.  
         [0025]    [0025]FIG. 5 is a partial sectional view similar to FIG. 3 of the inkjet printhead die in accordance with the present invention shown mounted to a single color inkjet printhead cartridge of FIG. 1.  
         [0026]    [0026]FIG. 6 is an enlarged plan view of an alternative inkjet printhead die in accordance with the present invention.  
         [0027]    [0027]FIG. 7 is a partial sectional view of the alternative inkjet printhead die of FIG. 6 mounted to a multicolor inkjet printhead cartridge. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    A replaceable inkjet printhead cartridge  16  useable in a thermal inkjet printing system  10  in accordance with the present invention is illustrated generally in FIGS.  1 - 3 . The printhead cartridge  16  includes a printhead die  40  that delivers fluid to firing resistors  70  positioned within the printhead die  40  using both slotted and edgefeed ink delivery systems.  
         [0029]    In FIG. 1, the printing system  10 , shown with its cover open, includes at least one replaceable fluid container  12  that is installed in a receiving station  14 . In one preferred embodiment, the printing system  10  includes two replaceable fluid containers  12 , with one single color fluid container  12  containing a black ink supply, and one multi-color fluid container  12  containing cyan, magenta and yellow ink supplies. With the replaceable fluid containers  12  properly installed into the receiving station  14 , fluid, such as ink, is provided from the replaceable fluid containers  12  to at least one inkjet printhead cartridge  16 . In one preferred embodiment, the printing system  10  includes two replaceable printhead cartridges  16 , with one single color printhead cartridge  16  for printing from the black ink supply, and one multi-color printhead cartridge  16  for printing from the cyan, magenta and yellow ink supplies.  
         [0030]    In operation, the inkjet printhead cartridges  16  are responsive to activation signals from a printer portion  18  to deposit fluid on print media  22 . As fluid is ejected from the printhead cartridges  16 , the printhead cartridges  16  are replenished with fluid from the fluid containers  12 . In one preferred embodiment, the replaceable fluid containers  12 , receiving station  14 , and the replaceable inkjet printhead cartridges  16  are each part of a scanning carriage  20  that is moved relative to the print media  22  to accomplish printing. The printer portion  18  includes a media tray  24  for receiving the print media  22 . As the print media  22  is stepped through a print zone, the scanning carriage  20  moves the printhead cartridges  16  relative to the print media  22 .  
         [0031]    Each printhead cartridge  16  has an inkjet printhead die  40 . The printer portion  18  selectively activates the printhead dies  40  (see FIGS. 3 and 4) of the printhead cartridges  16  to deposit fluid on print media  22  to thereby accomplish printing.  
         [0032]    The scanning carriage  20  of FIG. 1 slides along a slide rod  26  to print along a width of the print media  22 . A positioning means (not shown) is used for precisely positioning the scanning carriage  20 . In addition, a paper advance mechanism (not shown) moves the print media  22  through a print zone as the scanning carriage  20  is moved along the slide rod  26 . Electrical signals are provided to the scanning carriage  20  for selectively activating the printhead dies  40  of the printhead cartridges  16  by means of an electrical link, such as a ribbon cable  28 .  
         [0033]    [0033]FIG. 2 is a perspective view of a portion of the scanning carriage  20  showing the pair of replaceable fluid containers  12  properly installed in the receiving station  14 . For clarity, only a single inkjet printhead cartridge  16  is shown in fluid communication with the receiving station  14 . As seen in FIG. 2, each of the replaceable fluid containers  12  includes a latch  30  for securing the replaceable fluid container  12  to the receiving station  14 . In addition, the receiving station  14  includes a set of keys  32  that interact with corresponding keying features (not shown) on the replaceable fluid containers  12 . The keying features on the replaceable fluid containers  12  interact with the keys  32  on the receiving station  14  to ensure that the replaceable fluid containers  12  are compatible with the receiving station  14 .  
         [0034]    As seen in FIG. 3, the tri-color printhead cartridge  16  includes a cartridge body  42  having partition walls  44  and  46  that separate the cartridge body  42  into three separate chambers  48 ,  50  and  52 . The first chamber  48  includes a first capillary member  54  for a first ink color, the second chamber  50  includes a second capillary member  56  for a second ink color, and the third chamber  52  includes a third capillary member  58  for a third ink color. The first, second and third capillary members  54 ,  56 ,  58  receive their respective color ink from the tri-color fluid container  12 .  
         [0035]    In FIG. 5, the cartridge body  42  of the single color inkjet printhead cartridge  16  includes a single chamber  60  having a single capillary member  62  for a single color. In one preferred embodiment, this single color is black. The single capillary member  62  receives its respective color ink from the single color fluid container  12 .  
         [0036]    As seen in FIGS. 3 and 5 each of the tri-color (FIG. 3) and single color (FIG. 5) inkjet printhead cartridges  16  includes one inkjet printhead die  40  in accordance with the present invention. Because the printhead dies  40  of the single color and tri-color printhead cartridges  16  are similar only the printhead die  40  in connection with the tricolor printhead cartridge  16  of FIG. 3 will be described with particularity.  
         [0037]    As seen in FIG. 3, the inkjet printhead die  40  of the present invention functions to eject ink droplets  64  onto a print medium  22 . The printhead die  40  is defined by a substrate  66  that includes a base layer  68 , such as a semiconductor silicon substrate that provides a rigid chassis for the printhead die  40 , and which accounts for the majority of the thickness of the printhead die  40 . On top of the base layer  68  are a plurality of independently addressable ink energizing elements, such as firing resistors  70  (shown in FIG. 4) for heating ink to generate the ink droplets  64  in a known manner. In one preferred embodiment, the firing resistors  70  form part of a stack of thin film layers on top of the base layer  68 . On top of the base layer  68  is a barrier layer  76 , such as a photoresist polymer substrate. On top of the barrier layer  76  is an orifice plate  78 , such as a Ni substrate.  
         [0038]    As seen in FIG. 4, the die  40  has short side edges  74 . The firing resistors  70  are electrically linked (not shown) to electrical interconnects  72  on the short side edges  74 . In a known manner, the electrical interconnects  72  contact printer portion  18  contacts (not shown) to provide the energizing signals to the firing resistors  70 .  
         [0039]    As seen in FIGS. 3 and 4, the orifice plate  78  includes a plurality of nozzles  80  through which the ink droplets  64  are ejected. One nozzle  80  is associated with each firing resistor  70 . The barrier layer  76  defines a plurality of firing chambers  82  for the firing resistors  70 . One nozzle  80  and one firing resistor  70  is associated with each firing chamber  82 . The barrier layer  76  also defines a plurality of ink feed passageways  84  for delivering ink to the firing chambers  82 . In one preferred embodiment, one ink feed passageway  84  is associated with each firing chamber  82 . Alternatively, multiple ink feed passageways  84  could be associated with each firing chamber  82 . As seen in FIG. 3, the orifice plate  78  is oversized (i.e., larger than the barrier layer  76  and the base layer  68 ) to allow the inkjet printhead die  40  to be mounted to the cartridge body  42  using a suitable adhesive  86 .  
         [0040]    As seen in FIG. 3, the base layer  68  defines first, second and third ink refill channels  88 ,  90  and  92 , respectively, for delivering ink to the plurality of ink feed passageways  84  and ultimately to the firing chambers  82  for the firing resistors  70 . The first ink refill channel  88  is defined by a first long edge  94  of the base layer  68 . In particular, the first ink refill channel  88  is defined between the first edge  94  of the base layer  68  and a first wall  95  of the cartridge body  42 . The second ink refill channel  90  is defined by a second long edge  96  of the base layer  68 . In particular, the second ink refill channel  90  is defined between the second edge  96  of the base layer  68  and a second wall  97  of the cartridge body  42 . The third ink refill channel  92  is defined by a slot  98  extending through the base layer  68 . As seen in FIG. 4, the third ink refill channel  92  is positioned between and extends parallel to the first and second ink refill channels  88  and  90 . In essence, the first and second ink refill channels  88  and  90  are edgefeed ink refill channels, while the third ink refill channel  92  is a slot feed ink refill channel.  
         [0041]    As seen in FIG. 4, the first ink refill channel  88  is operatively associated with a first multiplicity or column  100  of firing resistors  70  immediately adjacent to the first long edge  94  of the base layer  68  via respective ink feed passageways  84 . The second ink refill channel  90  is operatively associated with a second multiplicity or column  102  of firing resistors  70  immediately adjacent to the second long edge  96  of the base layer  68  via respective ink feed passageways  84 . The third ink refill channel  92  is operatively associated with a third multiplicity or at least one column of firing resistors  70 . In one preferred embodiment, the third ink refill channel  92  is operatively associated with a third multiplicity of firing resistors  70  defined by two columns  104  and  106  of firing resistors  70  immediately adjacent to each side of the slot  98  extending through the base layer  68  via respective ink feed passageways  84 .  
         [0042]    For the tricolor printhead cartridge, the first, second and third ink refill channels  88 ,  90 ,  92  fluidically communicate with the first, second and third capillary members  54 ,  56 ,  58 , respectively, such that the first column  100  of firing resistors  70  eject a first ink color (i.e., cyan), the second column  102  of firing resistors  70  eject a second ink color (i.e., magenta), and the third and fourth columns  104 ,  106  of firing resistors  70  eject a third ink color (i.e., yellow). In the single color inkjet printhead cartridge  16  of FIG. 5 there is only a single capillary member  62  with which all the ink refill channels  88 ,  90 ,  92  fluidically communicate. As such, the first, second, third and fourth columns  100 ,  102 ,  104 ,  106  of firing resistors  70  all eject a single ink color (i.e., black).  
         [0043]    The inkjet printhead die  40  of the present invention substantially minimizes the size, strength and waste issues associated with present slotted printhead dies. In particular, the first, second and third ink refill channels  88 ,  90 ,  92  of the inkjet printhead die  40  of the present invention permits three color printing with a printhead die having only a single slot  98  as compared to the three slots needed for three color printing in a typical slotted printhead die. As such, the inkjet printhead die  40  can be made smaller in size then a comparable slotted only printhead die. In particular, the printhead die  40  of the present invention can exhibit a 600 μm width reduction based upon an average ink refill slot width of 300 μm.  
         [0044]    [0044]FIGS. 6 and 7 illustrate an alternative embodiment of an inkjet printhead die embodiment  40   a . Like parts are labeled with like numerals except for the inclusion of the subscript “a”. The alternative inkjet printhead  40   a  includes a fourth ink refill channel  120  defined by a further slot  122  extending through the base layer  68   a . This fourth ink refill channel  120  and the third ink refill channel  92   a  are positioned between the first and second ink refill channels  88   a ,  90   a  and are parallel thereto. The fourth ink refill channel  120  is operatively associated with a fourth multiplicity or at least one column of firing resistors  70   a . In one preferred embodiment, the fourth ink refill channel  120  is operatively associated with a fourth multiplicity of firing resistors  70   a  defined by two columns  124  and  126  of firing resistors  70   a  immediately adjacent to each side of the slot  122  extending through the base layer  68   a  via respective ink feed passageways  84   a . The first and second ink refill channels  88   a ,  90   a  fluidically communicate with the first capillary member  54   a , while the third and fourth ink refill channels  92   a ,  120  fluidically communicate with the second and third capillary members  56   a ,  58   a , respectively, such that the first and second columns  100   a ,  102   a  of firing resistors  70   a  eject a first ink color (i.e., cyan), the third and fourth columns  104   a ,  106   a  of firing resistors  70   a  eject a second ink color (i.e., magenta), and the fifth and six columns  124 ,  126  of firing resistors  70   a  eject a third ink color (i.e., yellow). Such a printhead die  40   a  would be comparable to some typical slotted printhead dies that include two columns of firing resistors for each of three slots.  
         [0045]    In one embodiment, the printhead die  40   a  is smaller in size than a typical three slot printhead die. In particular, the printhead die  40   a  of the present invention exhibits a 300 μm width reduction, based upon an average ink refill slot width of 300 μm due to the elimination of one slot.  
         [0046]    The inkjet printhead dies  40 ,  40   a  of the present invention can be incorporated into existing inkjet printhead cartridges used in thermal inkjet printing systems  10 .  
         [0047]    Although the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.