Abstract:
A tape automated bonding (TAB) device for a printhead cartridge of a printer includes a tape having a region capable of being substantially bisected by a centerline that defines a first side of the tape and a second side of the tape. Located on the tape is a printhead, and a plurality of contacts adapted to receive signals from the printer and to provide the signals to the printhead. The contacts are disposed such that the number of contacts on the first side is different from the number of contacts on the second side. The printhead is centrally aligned with the centerline or centrally offset from the centerline.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a continuation-in-part of application Ser. No. 09/682,300, filed Aug. 16, 2001, and which is included in its entirety herein by reference. 
     BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The present invention relates to a printhead cartridge for an inkjet printer. In particular, the present invention discloses a tape automated bonding (TAB) device for a printhead cartridge, the TAB device having an asymmetrical contact distribution and an offset printhead location that enable a size reduction of a corresponding flexible circuit board (FCB) within the printer. 
     2. Description of the Related Art 
     Please refer to FIG.  1 A. FIG. 1A is a perspective view of a prior art TAB  14  disposed on an inkwell  12  of a printhead cartridge  10 . The inkwell  12  is used to hold ink (not shown) for printing. The TAB  14  wraps around from a front surface  15  to a bottom surface  19  of the inkwell  12 . The TAB  14  comprises a plurality of contacts  16 , each with a corresponding trace  17  that electrically connects the contact  16  to a printhead  18 . The printhead  18  is mounted on the TAB  14 , and is situated on the bottom surface  19  of the inkwell  12 . The TAB  14  is substantially symmetrical with respect to a centerline A—A of the printhead cartridge  10 . Specifically, the plurality of contacts  16  are evenly distributed on both sides of the line A—A, and the longitudinal centerline of the printhead  18  is coincident with the line A—A. 
     Referring to FIG.  1 B and FIG. 1C, the printhead cartridge  10  is installed in and controlled by a printer  100 . The printer  100  comprises a flexible circuit board (FCB)  102  (not shown in FIG. 1B) to establish electrical contact with the plurality of contacts  16  of the TAB  14 , so that the printhead cartridge  10  can receive signals from the printer  100 . The printhead  18  performs a printing operation by jetting ink supplied from the inkwell  12  according to the signals received from the contacts  16 . Moreover, the FCB  102  accommodates two printhead cartridges  10  disposed side-by-side in the printer  100 . 
     The symmetrical arrangement of the plurality of contacts  16  and the printhead  18  on the TAB  14  can result in an FCB that is unnecessarily large and costly, that is, the prior art design is inefficient. 
     SUMMARY OF INVENTION 
     It is therefore a primary objective of the claimed invention to provide a tape automated bonding (TAB) device having an asymmetrical distribution of contacts and an offset printhead location to reduce a size of a corresponding contact surface within a printer. 
     Briefly summarized, the preferred embodiment of the claimed invention TAB device includes a tape having a region capable of being substantially bisected by a centerline that defines a first side of the tape and a second side of the tape. Disposed on the tape is a printhead, and a plurality of contacts adapted to receive signals from the printer and to provide the signals to the printhead. The contacts are disposed such that the number of contacts on the first side is different from the number of contacts on the second side. 
     According to the claimed invention, the printhead can be centrally aligned with the centerline or centrally offset from the centerline. Additionally, if the printhead is centrally offset from the centerline the plurality of contacts can be symmetrically equally distributed across the centerline. 
     It is an advantage of the claimed invention that the asymmetric distribution of contacts and the centrally offset printhead location allow for a significantly smaller flexible circuit board (FCB) in the printer. This results in a reduced cost of manufacture for the printer. 
     These and other objectives of the claimed invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1A is a perspective view of a prior art TAB disposed on a printhead cartridge. 
     FIG. 1B is a perspective view of a printer having the printhead cartridge of FIG. 1A installed. 
     FIG. 1C is a detailed view of a flexible circuit board of the printer of FIG.  1 B. 
     FIG. 2 is a perspective view of a TAB device according to the present invention disposed on a printhead cartridge. 
     FIG. 3 is a detailed view of the TAB device of FIG.  2 . 
     FIG. 4 is a detailed view of a second embodiment of a present invention TAB device. 
     FIG. 5 is a perspective view of a TAB device according to a third embodiment of the present invention disposed on a printhead cartridge. 
     FIG. 6 is a detailed view of the TAB device of FIG.  5 . 
     FIG. 7 is a detailed view of a fourth embodiment of a present invention TAB device. 
     FIG. 8 is a detailed view of a fifth embodiment of a present invention TAB device. 
     FIG. 9 is a detailed back view of the TAB device of FIG.  2 . 
     FIG. 10 is a detailed back view of the TAB device of FIG.  5 . 
    
    
     DETAILED DESCRIPTION 
     The specific design of a tape automated bonding (TAB) device is constrained by a printhead cartridge design and the design of a flexible circuit board (FCB) of a printer with which the TAB device is utilized. In the following detailed description, any geometric limitation recited for a TAB device reflects the geometry of the printhead cartridge and the FCB for which the TAB is designed, but should not be construed as limiting all such TAB devices that embody the teachings of the present invention. The present invention TAB device can be applied to various types of FCB and printhead cartridge geometries. 
     FIG. 2 shows a perspective view of a present invention TAB device  30 , which typically comprises a flexible polymer tape and a plastic L-shaped base (piece  31  shown in FIG.  9 ), disposed on an inkwell  22  of a printhead cartridge  20 . The inkwell  22  is used to hold ink (not shown) for printing. The TAB device  30  is disposed on the inkwell  22  on a front surface  24  and a bottom surface  26  of the inkwell  22 . The TAB device  30  is centrally aligned with a centerline B—B of the printhead cartridge  20 , such that the longitudinal centerline of the TAB device  30  is coincident with the centerline B—B. The printhead cartridge  20  is installed in and controlled by a printer to eject ink onto a page of printable media, such as paper. The TAB device  30  serves as the electronic interface between an FCB of the printer and the printhead cartridge  20  by receiving signals from the printer. The TAB device  30  also functions to spray ink from the inkwell  22  onto a page of paper when triggered to by the received signals. 
     Please refer to FIG. 3, which shows a detailed view of the TAB device  30 . In FIG. 3, the flexible tape of the TAB device  30  is shown unfolded and detached from the printhead cartridge  20  of FIG.  2 . The tape of the TAB device  30  comprises a plurality of electrical contacts  32  arrayed in columns  32   c , each contact  32  having a corresponding trace  34  that electrically connects the contact  32  to a printhead  36 . The printhead  36  is the component of the TAB device  30  that sprays ink when the printhead cartridge  20  is controlled by the printer. The printhead  36  is centrally aligned with the centerline B—B, meaning that the longitudinal centerline of the printhead  36  is coincident with the centerline B—B of the printhead cartridge  20 . The contacts  32  are asymmetrically disposed in four vertical columns  32   c  on either side of the centerline B—B. The centerline B—B defines two equal sides  30   a  and  30   b  of the TAB  30 , with side  30   a  having effectively the same surface area as side  30   b . One column of contacts  32   c  is situated on the left side  30   b  of the line B—B, and three columns of contacts  32   c  are located on the right side  30   a  of the line B—B. The traces  34  are disposed in a pattern that lends itself to efficient routing. By providing an asymmetric number of columns  32   c  between the sides  30   a  and  30   b , an asymmetric number of contacts  32  is provided between the sides  30   a  and  30   b . If the contacts  32  are not arrayed as columns, then at least a suitably larger number of contacts  32  should be disposed on one side  30   a ,  30   b  than the other side  30   b ,  30   a , so as to provide for a reduction in size of the FCB within the printer. Typically, this will be at least five percent or more contacts on one side  30   a ,  30   b  than on the other side  30   b ,  30   a . Alternatively, a single contact  32  could be construed as a column  32   c . Note, also, that it is not strictly necessary for the columns  32   c  to be parallel to the centerline B—B of the TAB device  30 . Column  32   c  that are perpendicular to the centerline B—B are also possible. The above is equally applicable to the following embodiments. 
     Illustrated in FIG. 4 is a second embodiment of the present invention. As in the previously described embodiment, the printhead  36  is centrally aligned with the centerline B—B of the TAB device  30 . In this second embodiment, however, all the contacts  32  are disposed in four columns  32   c  on the right side  30   a  of the centerline B—B. Again, the traces  34  are disposed in a suitable pattern. Of course, it is also possible to place all contact  32  onto the left side  30   b.    
     A back view of the TAB device  30  removed from the inkwell  22  of the printhead cartridge  20  is shown in FIG.  9 . Illustrated in FIG. 9 is a plurality of pins  37  that detachably mechanically attach the TAB device  30  to the inkwell  22  of the printhead cartridge  20 . The pins  37  are located on a region of the TAB device  30  that contacts the front surface  24  of the inkwell  22 , but additional pins could also be located on a region of the TAB device  30  that contacts the bottom surface  26  of the inkwell  22 . The pins  37  are small metal flaps that mate with corresponding recesses in the inkwell  22 . Alternatively, the pins  37  could be round metal pins or a similar fastening structure of either metallic or nonmetallic (such as the same plastic material as the base  31  of the TAB device  30 ) construction. The arrangement of the pins  37  is designed to provide a suitable mechanical strength of the connection of the TAB device  30  to the inkwell  22 . Also shown in FIG. 9 is an ink inlet pipe  38  that is used to deliver ink from the inkwell  22  to the printhead  36 . When the TAB device  30  is connected to the inkwell  22 , the ink inlet pipe  38  penetrates the inkwell  22  and also presses into foam (not shown) containing ink in the inkwell  22  and forms a path for ink to flow from the inkwell  22  to the printhead  36 . The base  31  also contains a hole connecting to the printhead  36  to deliver the ink from the inkwell  22  to the printhead  36 . To facilitate this, the ink inlet pipe  38  is located directly opposite the printhead  36 . 
     A third embodiment of present invention is shown in FIG. 5. A flexible tape of the TAB device  50  is disposed on an inkwell  42  of a printhead cartridge  40 . The design and operation of the printhead cartridge  40  are identical to the design and operation of the printhead cartridge  20  of FIG. 2, except for the location of the TAB device  50 . The TAB device  50  is centered about a line D—D, which is offset from a centerline C—C of the printhead cartridge  40 . The location of the TAB device  50  on the printhead cartridge  40  is as such because of the design of an FCB of a printer for which the printhead cartridge  40  is intended. 
     Please refer to FIG. 6, which shows a detailed view of the tape of the TAB device  50 . In FIG. 6, the flexible tape of the TAB device  50  is shown unfolded and detached from the printhead cartridge  40 . The TAB device  50  comprises a plurality of contacts  52 , each with a corresponding trace  54  that electrically connects the contact  52  to a printhead  56 . The printhead  56  is centrally offset to the left with respect to the centerline D—D of the TAB device  50 . Similarly, it is of course possible to offset the printhead  56  to the right of the centerline D—D. Centerline D—D divides the TAB device  50  into two sides of equal area, a right side  50   a  and a left side  50   b . Specifically, the longitudinal centerline of the printhead  56  is parallel to but not coincident with the centerline D—D. The contacts  52  are symmetrically disposed in four vertical columns  52   c , with two columns  52   c  on either side  50   a ,  50   b  of the centerline D—D. The traces  54  are disposed accordingly. 
     Illustrated in FIG. 7 is a fourth embodiment of the present invention. As in the previously described third embodiment, the printhead  56  is centrally offset to the left with respect to the centerline D—D. In this fourth embodiment, however, the contacts  52  are disposed in an asymmetric pattern. Twelve contacts  52  are located on the left side  50   b  of the centerline D—D in three column  52   c , and four contacts  52  are located on the right side  50   a  of the centerline D—D in a single column  52   c . Again, the traces  54  are disposed in a suitable arrangement to electrically connect the contacts  52  with the printhead  56 . 
     A fifth embodiment of the present invention is illustrated in FIG.  8 . In this embodiment, the printhead  56 , the entire plurality of contacts  52 , and all connecting traces  54  are all disposed completely on the left side of the TAB centerline D—D, so that all column  52   c  of contacts  52  are disposed on a single side, the side  50   b . Traces  54  may run into side  50   a  from side  50   b  without affecting the purpose of the present invention, which is to provide for a reduction in size to the FCB disposed within a printer that makes electrical contact with the contacts  52 . 
     A back view of the TAB device  50  removed from the inkwell  42  of the printhead cartridge  40  is shown in FIG.  10 . Illustrated in FIG. 10 is a plurality of pins  57  that detachably mechanically attach the TAB device  50  to the inkwell  42  of the printhead cartridge  40 . The pins  57  are small metal flaps that mate with corresponding recesses in the inkwell  42 . Similar to the TAB device  30  of FIG. 9, the location, arrangement, and design of the pins  57  are selected to provide a suitable mechanical strength of the connection of the TAB device  50  to the inkwell  42 . Also shown in FIG. 10 is an ink inlet pipe  58  that is used to deliver ink from the inkwell  42  to the printhead  56 . When the TAB device  50  is connected to the inkwell  42 , the ink inlet pipe  58  penetrates the inkwell  42  and also presses into foam (not shown) containing ink in the inkwell  42  and forms a path for ink to flow from the inkwell  42  to the printhead  56 . The base  51  also contains a hole connecting to the printhead  56  to deliver the ink from the inkwell  42  to the printhead  56 . To facilitate this, the ink inlet pipe  58  is located directly opposite the printhead  56 . 
     In contrast to the prior art, the present invention supports both an asymmetrical distribution of contacts, and an offset printhead location to reduce a size of the corresponding FCB within the printer. This results in a lower cost FCB and a corresponding lower production cost of the printer. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.