Abstract:
This present invention provides an ink jet printhead and method of delivering ink to the printhead. The printhead has a substrate, a nozzle layer, and a plurality of bubble generators. A plurality of first chambers and a plurality of second chambers are formed between the nozzle layer and the top of the substrate. A central ink flow channel and a periphery ink flow channel for delivering ink to the chambers are formed in the substrate. The characteristic of the present invention is positioning the central ink flow channel and the periphery ink flow channel together on the substrate so that the amount of the nozzles per unit area of the printhead is increased.

Description:
BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The present invention relates to the field of ink jet printheads and associated ink delivering method, and more particularly, to a high-density ink jet printhead having a two-directional central ink flow channel and a one-directional periphery ink flow channel. 
     2. Description of the Related Art 
     Please refer to FIG.  1 . FIG. 1 is a cross-sectional diagram of a prior art printhead  10 . Structures similar to the printhead  10  are disclosed in U.S. Pat. Nos. 4,680,859 and 4,683,481 of Samuel A. Johnson and assigned to Hewlett-Packard Company. The printhead  10  comprises a central ink feed slot  12  formed at a center portion of a substrate  14 . The ink feed slot  12  may be formed by sand blasting, laser cutting, or etching techniques. Heater resistors  16  are provided on both sides of the ink feed slot  12  for generating bubbles during an ink jet printing operation. An orifice plate  18  with a plurality of nozzles  22  formed therein is positioned on the substrate  14  and each of the nozzles  22  is positioned corresponding to one heater resistor  16 . During an ink jet printing operation, ink will flow through the central ink feed slot  12  to chambers  24  between the orifice plate  18  and the substrate  14 . The heater resistors  16  thereafter heat the ink flow into the chambers  24  to generate bubbles for pressurizing the ink, thereby forming an ink droplet  26 . 
     Please refer to FIG.  2 . FIG. 2 is a cross-sectional diagram of a prior art printhead  30 . Similar structure is disclosed in U.S. Pat. No. 5,278,584 of Brian J. Keefe et al. and assigned to Hewlett-Packard Company. As shown in FIG. 2, the printhead  30  comprises a central ink slot  32  formed between a printhead cartridge  31  and a substrate  33 . channels  34  are formed between the end of the central slot  32  and vaporization chambers  36 . Each of the vaporization chambers  36  is provide with a thin film resistor  38  for generating a bubble. During an ink jet printing operation, ink from an ink reservoir (not shown) flows through the central slot  32  and split channels  34  to the vaporization chambers  36 . When the thin film resistors  38  are energized, the ink within the vaporization chambers  36  is ejected, as illustrated by the emitted drops of ink  42 . 
     Please refer to FIG.  3 . FIG. 3 is another prior art printhead  50  disclosed in U.S. Pat. No. 6,010,208 of James Harold Powers et al. and assigned to Lexmark International Inc. Two rows of nozzles  54  are located one each side of a manifold  52  of the printhead  50 . Ink flows through the central manifold  52  laterally to the chambers  56  corresponding to the nozzles  54 . 
     Please refer to FIG.  4  and FIG.  5 . FIG. 4 is a schematic diagram showing a prior art nozzle array of a color printhead  60 . FIG. 5 is a schematic, cross-sectional view of an ink cartridge  70  having a printhead  60  of FIG. 4 mounted thereon. The ink cartridge  70  comprises three ink reservoirs  72  for storing ink of different colors such as yellow, magenta, and cyan. The printhead  60  includes a substrate with three ink slots  62  and a plurality of nozzles  64  arranged in six columns on an orifice plate  61 . Each of the six columns of nozzles  64  is located on a side of the three ink slots  62  which are connected with associated ink reservoirs  72 . Likewise, ink from the ink reservoirs  72  flows through the ink slots to the chambers and then splits into two flows in opposite directions. The heater resistors  66  then create ink bubbles to form drops of ink out of the nozzles  64 . FIG. 6 is nozzle array of another prior art color printhead  80 . Similarly, printhead  80  comprises six rows of nozzles  64  and three ink slots  62  (indicated by a dashed line). The difference between the printhead  60  and printhead  80  is the arrangement of the ink slots  62 . 
     From above, ink from an ink reservoir is delivered either through a central ink feed slot or edge feed path (through an edge of a substrate). Unfortunately, the nozzles must be located near the ink slot, thus limiting the nozzle number of a printhead and resolution. 
     SUMMARY OF INVENTION 
     Accordingly, the primary objective of the present invention is to provide a printhead capable of delivering colors of ink simultaneously from a central path and an edge path. 
     Another objective of this invention is to provide an ink delivery method for increasing nozzle number in a unit area. Four or more columns of nozzles may be packed into a printhead having a smaller printhead surface, thereby improving its resolution. 
     Still another objective of this invention is to provide a printhead having a smaller size that is capable of printing three or more colors of ink. 
     Briefly, the printhead has a substrate, a nozzle layer, and a plurality of bubble generators. A plurality of first chambers and a plurality of second chambers are formed between the nozzle layer and the top of the substrate. A central ink flow channel and a periphery ink flow channel for delivering ink to the chambers are formed in the substrate. The characteristic of the present invention is that positioning the central ink flow channel and the periphery ink flow channel together on the substrate so that the amount of the nozzles per unit area of the printhead is increased. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a cross-sectional diagram of a prior art printhead. 
     FIG. 2 is a cross-sectional diagram of another prior printhead. 
     FIG. 3 is still another prior art printhead. 
     FIG. 4 is a schematic diagram showing a prior art nozzle array of a color printhead. 
     FIG. 5 is a schematic, cross-sectional view of an ink cartridge having a printhead of FIG. 4 mounted thereon. 
     FIG. 6 is nozzle array of another prior art color printhead. 
     FIG. 7 is a schematic diagram showing the nozzle array of an ink jet printhead according to the first preferred embodiment of this invention. 
     FIG. 8 is a schematic, cross-sectional view of an ink cartridge having a printhead of FIG. 7 mounted thereon. 
     FIG. 9 is a schematic diagram showing the nozzle array of an ink jet printhead according to second preferred embodiment of this invention. 
     FIG. 10 is a schematic, cross-sectional view of an ink cartridge having a printhead of FIG. 9 mounted thereon. 
     FIG. 11 is a plane view of a printhead according to the third preferred embodiment of this invention. 
     FIG. 12 is a cross sectional view of the printhead of FIG. 11 when mounted on a color ink cartridge. 
     FIG. 13 is a plane view of a printhead according to the fourth embodiment of this invention. 
     FIG. 14 is a cross sectional view of the printhead of FIG. 13 when mounted on a color ink cartridge. 
     FIG. 15 is a plane view of a printhead according to the fifth embodiment of this invention. 
     FIG. 16 is a cross sectional view of the printhead of FIG. 15 when mounted on a color ink cartridge. 
     FIG. 17 is a plane view of a printhead according to the sixth embodiment of this invention. 
     FIG. 18 is a cross sectional view of the printhead of FIG. 15 when mounted on a color ink cartridge. 
     FIG. 19 is a plane view showing the seventh embodiment of this invention 
     FIG. 20 is a plane view showing the eighth embodiment of this invention. 
    
    
     DETAILED DESCRIPTION 
     Please refer to FIG.  7  and FIG.  8 . FIG. 7 is a schematic diagram showing the nozzle array of an ink jet printhead  100  according to the first preferred embodiment of this invention. FIG. 8 is a schematic, cross-sectional view of an ink cartridge  110  having a printhead  100  of FIG. 7 mounted thereon. The printhead  100  comprises a substrate  101 , a nozzle layer  102 , and a plurality of bubble generators  103 . The ink cartridge  110  comprises an ink reservoir  111  for storing ink. A tape automated bonding (TAB) circuit  109  is connected to the nozzle layer  102  and attached to the housing of the ink cartridge  110  with an adhesive layer (not shown). A first central ink flow channel  104  is formed within the substrate  101 . A first periphery ink flow channel  106  and a second periphery ink flow channel  108  are formed at an edge of the substrate  101 . The first central ink flow channel  104  has a first central opening  105  on an upper surface of the substrate  101 . The nozzle layer  102  is positioned above the substrate. First chambers  122 , second chambers  126 , third chambers  124 , and fourth chambers  128  are formed between the upper surface of the substrate  101  and the nozzle layer  102 . The bubble generators  103  may be a heater resistor. The bubble generators are positioned below associated nozzles  112  for pressing drops of ink form out of the chambers  122 ,  124 ,  126 , and  128 . 
     The second periphery ink flow channel  108 , fourth chambers  128 , first chambers  122 , central opening  105 , third chambers  124 , second chambers  126 , and first periphery ink flow channel  106  are laid in sequence from left to right as indicated in FIG.  7  and FIG.  8 . The first chambers  122  are located between the central opening  105  and the second periphery ink flow channel  108 . The third chambers  124  are located between the central opening  105  and first periphery ink flow channel  106 . During a jet printing operation, ink from the ink reservoir  111  flows through the first central ink flow channel  104  and the central opening  105  to the first chamber  122  and third chambers  124  (two-directional ink delivery). Meanwhile, ink flows through the first periphery ink flow channel  106  at one side of the edge of the substrate  101  to the second chambers  126  and also through the second periphery ink flow channel  108  at another side of the edge of the substrate  101  to the fourth chambers  128  (single-directional ink delivery). 
     In this embodiment, the first periphery ink flow channel  106  and second periphery ink flow channel  108  are confined by walls of the ink reservoir  111  and the edges of the substrate  101 . In contrast to the prior art, such configuration enables the printhead  100  to provide additional third chambers  126  and fourth chambers  128  at periphery of the substrate  101  between the substrate  101  and the nozzle layer  102 . This configuration increases resolution, namely, nozzle number within a unit area of the printhead  100 . In another embodiment of this invention, only one of the first periphery ink flow channel  106  and second periphery ink flow channel  108  is provided. In either case, chambers corresponding to the omitted periphery ink flow channel are also omitted. 
     Please refer to FIG.  9  and FIG.  10 . FIG. 9 is a schematic diagram showing the nozzle array of an ink jet printhead  150  according to another preferred embodiment of this invention. FIG. 10 is a schematic, cross-sectional view of an ink cartridge  110  having a printhead  150  of FIG. 9 mounted thereon. The printhead  150  is very similar to the printhead  100  of FIG. 7 except that the chambers  122 ,  124 ,  126 , and  128  and associated nozzles  112  are arranged in two columns on both sides of the central opening  105  as indicated in FIG.  9 . 
     With reference to FIG. 7, ink stored in the ink reservoir  111  is a single color, for example, black color. Distance between adjacent two nozzles in each column (corresponding to chambers  122 ,  124 ,  126 , and  128 ) is indicated as “d”. This means that resolution for each column is equal, for example, 300 dpi (dots per inch) for each column. Most importantly, the nozzles in two adjacent columns are arranged alternately with an offset of, for example, d/4, as indicated with a dashed line in FIG.  7 . In such way, during an ink jet printing operation, the printhead  100  may achieve a resolution of about four times the single column resolution (ex. 300 dpi), namely 1200 dpi. Likewise, in FIG. 9, the nozzles  112  in different columns are arranged alternatively with an offset of d/8. In this case, the resolution of the printhead  150  is about 2400 dpi with respect to a single column resolution of 300 dpi. 
     Please refer to FIG.  11  and FIG.  12 . FIG. 11 is a plane view of a printhead  170  according to the third preferred embodiment of this invention. FIG. 12 is a cross sectional view of the printhead  170  of FIG. 11 when mounted on a color ink cartridge  180 . The color ink cartridge  180  comprises a first ink reservoir  132 , a second ink reservoir  134 , and a third ink reservoir  136  for storing three different colors of ink. These three different colors of ink may be, for example, magenta, yellow, and cyan, or may be light magenta, light yellow, and light cyan. The ink reservoirs  132 ,  134 , and  136  are independent and not connected to each other. Likewise, the printhead  170  comprises a substrate  101  and a nozzle layer  102 . There are a number of first chambers  122 , second chambers  126 , third chambers  124 , and fourth chambers  128  provided between the substrate  101  and the nozzle layer  102 . Similarly, a first central ink flow channel  104 , a first periphery ink flow channel  106  and a second periphery ink flow channel  108  are formed in the substrate  101  for flowing ink stored in the first ink reservoir  132 , second ink reservoir  134 , and third ink reservoir  136 , respectively. The first chambers  122  and the third chambers  124  are both arranged in a single column as shown in FIG.  11  and are connected with the first ink reservoir  132  through the first central opening  104 . The second chambers  126  and the fourth chambers  128  are arranged in dual column formation, wherein the second chambers  126  are connected with the second ink reservoir  134  through the first periphery ink flow channel  106 , and the fourth chambers  128  are connected with the third ink reservoir  136  through the second periphery ink flow channel  108 . 
     In the third embodiment, since the first chambers  122  and the third chambers  124  provide the same color of ink, the arrays of the first chambers  122  and the third chambers  124  are arranged in an intersecting manner to improve resolution of the printhead  170 . Further, both of the second chambers  126  and the fourth chambers  128  are arranged in an intersecting manner as shown in FIG. 11 in order to achieve the same resolution as the first chambers  122  and second chambers  124 . By such design, the printhead  170  provides three colors of ink at the same time. 
     Please refer to FIG.  13  and FIG.  14 . FIG. 13 is a plane view of a printhead  190  according to the fourth embodiment of this invention. FIG. 14 is a cross sectional view of the printhead  190  of FIG. 13 when mounted on a color ink cartridge  200 . The difference between the ink cartridge  200  and the ink cartridge  180  of FIG. 12 is that besides the first ink reservoir  132 , second ink reservoir  134 , and third ink reservoir  136 , the color ink cartridge  200  further comprises a fourth ink reservoir  196  for storing another color of ink. The ink reservoirs  132 ,  134 ,  136 , and  196  are independent and not connected to each other. In addition, besides the first central ink flow channel  104 , the first periphery ink flow channel  106  and the second periphery ink flow channel  108 , the substrate  101  further comprises a second central ink flow channel  192  located between the first central ink flow channel  104  and the first periphery ink flow channel  106 . As shown in FIG. 13, a plurality of third chambers  124  arranged in two intersected columns are distributed on two sides of the second central ink flow channel  192  (indicated by a dashed line) between the nozzle layer  102  and the substrate  101 . Likewise, the plurality of the first chambers  122  are distributed on two opposite sides of the first central ink flow channel  104 . In this way, the printhead  190  is capable of providing four colors of ink. For example, black ink that is typically stored in another ink cartridge may be stored in the ink reservoir  196 , while the other three ink reservoirs  132 ,  134 , and  136  may store magenta, yellow, and cyan, or may store light magenta, light yellow, and light cyan, respectively. 
     Please refer to FIG.  15  and FIG.  16 . FIG. 15 is a plane view of the printhead  210  according to the fifth embodiment of this invention. FIG. 16 is a cross sectional view of the printhead  210  of FIG. 15 when mounted on a color ink cartridge  220 . The printhead  210  is capable of providing five colors of ink. The major difference between the printhead  190  and printhead  210  is that the printhead  210  comprises a third central ink flow channel  212  located between the first central ink flow channel  104  and the second periphery ink flow channel  108 . A plurality of fifth chambers  194  arranged in two intersected columns are located on two opposite sides of the third central ink flow channel  212  between the nozzle layer  102  and the substrate  101 . The first chambers  122  are distributed on two opposite sides of the first central ink flow channel  104 . The third chambers  124  are distributed on two opposite sides of the second central ink flow channel  192 . In addition to the first ink reservoir  132 , second ink reservoir  134 , third ink reservoir  136 , and fourth ink reservoir  196 , the color ink cartridge  220  further comprises a fifth ink reservoir  216  for storing a fifth color of Likewise, the five ink reservoirs  132 ,  134 ,  136 ,  196 , and  216  are independent and are not connected to each other. In this embodiment, the first ink reservoir  132 , the fourth ink reservoir  196 , and the fifth ink reservoir  216  may store magenta ink, yellow ink, and cyan ink, respectively. The second ink reservoir  134  and the third ink reservoir  136  may store light magenta ink and light cyan ink, respectively. By this configuration, the color level of the printhead  210  may be improved. 
     Please refer to FIG.  17  and FIG.  18 . FIG. 17 is a plane view of the printhead  230  according to the sixth embodiment of this invention. FIG. 18 is a cross sectional view of the printhead  230  of FIG. 15 when mounted on a color ink cartridge  240 . The printhead  230  is capable of providing four colors of ink. The printhead  230  comprises a first central ink flow channel  104 , a first periphery ink flow channel  106 , a second periphery ink flow channel  108 , a second central ink flow channel  192 , and a third central ink flow channel  212 . The ink cartridge  240  comprises four independent ink reservoirs  132 ,  134 ,  136 , and  196 , wherein the first reservoir  132 , the second ink reservoir  134 , and fourth ink reservoir  1   96  may store cyan ink, yellow ink, and magenta ink, respectively. The third ink reservoir  136  may store black ink. In this case, the black ink flows through the third central ink flow channel  212  to the fifth chambers  194  and through the second periphery ink flow channel  108  to the fourth chambers  128 . 
     Please refer to FIG.  19 . FIG. 19 is a plane view showing an array of the nozzles of the printhead  250  according to the seventh embodiment of this invention. The printhead  250  provides three colors of ink during an ink jet printing operation. As shown in FIG. 19, the printhead  250  comprises a plurality of nozzles arranged in a 4 column×3 row configuration. Three central ink flow channels  104   m,    104   c,    104   y  (indicated by a dashed line), three first periphery ink flow channels  106   m,    106   c,    106   y,  and three second periphery ink flow channels  108   m,    108   c,    108   y  are provided. The central ink flow channels  104   m,    104   c,    104   y  are used to deliver ink to the second column of nozzles and third column of nozzles  112 . The first periphery ink flow channels  106   m,    106   c,    106   y  are used to deliver ink to nozzles  112  in fourth column. The second periphery ink flow channels  108   m,    108   c,    108   y  are used to deliver ink to nozzles  112  in first column. The nozzles  112  in first column are connected with a first ink reservoir (not shown). The nozzles  112  in the second column are connected with a second ink reservoir. The nozzles  112  in the third column are connected with a third ink reservoir. The three ink reservoirs store different colors of ink and are independent. 
     Please refer to FIG.  20 . FIG. 20 is a plane view showing an array of the printhead  260  according to the eighth embodiment of this invention. The printhead  260  is capable of providing five colors of ink during an ink jet printing operation. As shown in FIG. 20, the printhead  260  comprises a plurality of nozzles  112  arranged in a 4 column×3 row configuration. Three central ink flow channels  104   m,    104   c,    104   y  (indicated by a dashed line), one first periphery ink flow channel  106 , and one second periphery ink flow channel  108  are provided. The central ink flow channels  104   m,    104   c,    104   y  are used to deliver ink to the second column of nozzles and third column of nozzles  112 . The first periphery ink flow channel  106  is used to deliver ink to nozzles  112  in fourth column. The second periphery ink flow channel  108  is used to deliver ink to nozzles  112  in first column. The nozzles  112  in first column are connected with a first ink reservoir (not shown). The nozzles  112  in the fourth column are connected with a second ink reservoir. The nozzles  112  in the second and third columns of the first row are connected with a third ink reservoir. The nozzles  112  in the second and third columns of the second row are connected with a fourth ink reservoir. The nozzles  112  in the second and third columns of the third row are connected with a fifth ink reservoir. Likewise, the five ink reservoirs store different colors of ink and are independent. 
     In contrast to the prior art, the printhead of this invention utilizes both a central ink delivery path (through central ink flow channel) and an edge ink delivery path (through the periphery ink flow channel). Further, since four or more columns of nozzles may be packed into a printhead having a smaller printhead surface, nozzle number within a unit area is significantly increased, thereby improving its resolution. Alternately, this invention may provide a printhead having a smaller size that is capable of printing three or more colors of ink. 
     Those skilled in the art will readily observe that numerous modification and alterations of the device may be made while retaining the teachings of the invention. For example, the printhead of this invention may be suitable for fuel injection systems, cell sorting, drug delivery systems, direct print lithography, and micro jet propulsion systems. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.