Patent Publication Number: US-2010110454-A1

Title: Display device having printer

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     The present application is a Continuation of U.S. application Ser. No. 10/922,971, filed on Aug. 23, 2004, which is a Continuation-In-Part of U.S. application Ser. No. 10/803,074, filed on Mar. 18, 2004. 
    
    
     FIELD OF INVENTION 
     The present invention relates to an integrated printing and flat panel display unit. 
     The invention has been developed primarily as an integrated peripheral unit that is connectable to a personal computer such as Macintosh or IBM compatible PC. However, it will be appreciated by those skilled in the art that the invention is not limited to these applications. 
     CO-PENDING APPLICATIONS 
     Various methods, systems and apparatus relating to the present invention are disclosed in the following co-pending applications filed by the applicant or assignee of the present invention simultaneously with the present application: 
     Ser. Nos. 10/922,970 10/922,836 10/922,842 10/922,848 10/922,843 U.S. Pat. Nos. 7,125,185 7,229,226 
     The disclosures of these co-pending applications are incorporated herein by cross-reference. 
     CROSS-REFERENCES 
     Various methods, systems and apparatus relating to the present invention are disclosed in the following co-pending applications filed by the applicant or assignee of the present invention. The disclosures of all of these co-pending applications are incorporated herein by cross-reference. 
     
       
         
           
               
               
               
               
               
             
               
                   
               
             
            
               
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     BACKGROUND 
     Flat panel displays are known. A popular technology presently in use is the Thin Film Transistor (TFT) Liquid Crystal Display (LCD), which comprises an array of liquid crystal pixel elements driven by respective thin film transistors. In each element, liquid crystal is sandwiched between glass plates. A backlight is positioned behind the LCD layer relative to a position from which the display will be viewed. A polarizing screen is placed between the backlight and the LCD layer, and another polarizing screen is positioned on the other side of the LCD layer. The polarizing screens are orientated to be orthogonally polarizing with respect to each other. 
     Using the corresponding TFT to alter a voltage applied to the liquid crystal element causes a change in its crystalline structure that correspondingly alters the polarization of light passing through the element from the backlight. This change in polarization causes a corresponding change in the amount of light transmitted through the polarizing screens and LCD element. 
     Multiple colors are dealt with by providing each pixel with multiple LCD pixel elements (usually red, green and blue) that can individually be controlled for each pixel, thereby allowing various color combinations. 
     The design and operation of TFT LCD screens is well known to those skilled in the art and so is not described in more detail in this document. 
     Typically, flat panel displays, including TFT LCD displays, are more expensive than Cathode Ray Tube (CRT) display of comparable performance. However, the relative lightness and compactness of flat panel displays (particularly in terms of front to back depth) make them particularly suitable for situations where a small footprint is desirable. They are ubiquitous in laptop computers, and have come down in price sufficiently for them to be attractive to many desktop computer users. The relatively shallow front to back depth means that the display can be pushed back further from the user than would be possible with a CRT in many situations, thereby allowing better viewing comfort. Flat panel displays also enable a user to utilize considerably smaller areas than would be possible with an equivalent CRT display, which can be important in situations where a wall, partition or divider is located close to a work area in which the display is to be situated. 
     Often, computer users wish to print a hard copy of documents, images, web pages and the like. Usually, a printer is provided as a peripheral device that can be connected to the computer using a suitable cable. Alternatively, the computer can be connected via a Local Area Network (LAN) or other communications network. Printers can be bulky, and tend take up additional space in a user&#39;s work area. Where space is at a premium, such printers can be intrusive or at least inconvenient. In many cases where a flat panel display is selected, space is already at a premium, so printers can exacerbate the problem. 
     SUMMARY OF THE INVENTION 
     In a first aspect the present invention provides a display device for use as a computer monitor, the display device comprising:
         a flat panel display for displaying images from a computer;   a printhead for printing onto print media;   a sheet feeder for receiving at least one sheet of the print media and feeding the at least one sheet to the printhead for printing, wherein the sheet feeder is at least partially fed by gravity.       

     Optionally the sheet feeder is configured to receive a single sheet of the print media at a time. 
     Optionally the sheet feeder includes:
         a multi-sheet media holder; and   a sheet media separator configured to separate a single sheet of the media from other sheets of the media in the media hole for supply to the printhead.       

     Optionally the sheet media separator includes at least one rotatable grip member configured to engage an edge of the sheet media to be separated. 
     Optionally the rotatable grip member is generally ‘D’-shaped in cross section. 
     Optionally the device is configured to receive print data to be printed, and display data to be displayed on the flat panel display, from a computer system. 
     Optionally the device includes a connection configured to allow releasable operative connection of the computer system to the display device, for receiving the print data and the display data from the computer system. 
     Optionally the connection includes at least one socket for accepting at least one corresponding data cable. 
     Optionally the connection includes a wireless receiver for receiving the print data and the display data. 
     Optionally the connection is a Universal Synchronous Bus (USB) connection. 
     Optionally the printer is a process color printer. 
     Optionally the printer is an inkjet printer. 
     Optionally the printer has more than 5,000 inkjet nozzles. 
     Optionally the printer is a page-width printer. 
     Optionally the flat panel display measures at least 14 cm on the diagonal. 
     In a second aspect the present invention provides a display device for use as a computer monitor, the display device comprising:
         a flat panel display for displaying images from a computer;   a stand for holding the flat panel display in at least one operative position; and   a printer, the printer including a printhead for printing onto paper;   wherein the stand is configured such that the at least one operative position includes one in which the flat panel display makes an angle of 0 to 45 degrees to the vertical.       

     Optionally the stand enables adjustment of the flat panel display into a number of different operative positions. 
     Optionally the stand enables continuous adjustment between the operative positions. 
     Optionally the device is configured to receive print data to be printed, and display data to be displayed, from a computer system. 
     Optionally the display device includes a connection configured to allow releasable operative connection of the computer system to the display device, for receiving the print data and the display data from the computer system. 
     Optionally the connection includes at least one socket for accepting at least one corresponding data cable. 
     Optionally the connection includes a wireless receiver for receiving the print data and/or the display data. 
     Optionally the connection is a Universal Synchronous Bus (USB) connection. 
     Optionally the device further includes a paper feed mechanism for feeding paper to the printhead for printing, the printhead being arranged to print onto the paper. 
     Optionally the paper feed mechanism is configured to position the paper substantially parallel in at least one direction with respect to a plane defined by the flat panel display. 
     Optionally the paper feed mechanism is configured to accept a single sheet of paper at a time for printing. 
     Optionally the paper feed mechanism includes a paper separator for feeding a single sheet of paper to the printhead from a stack of sheets of paper. 
     Optionally the printer is a process color printer. 
     Optionally the printer is an inkjet printer. 
     Optionally the printer has more than 5,000 inkjet nozzles. 
     Optionally the printer is a page-width printer. 
     Optionally the flat panel display measures at least 14 inches on the diagonal. 
     Optionally the device further includes at least two of the printheads, the printheads being disposed on either side of a path through which the paper is fed for printing, thereby enabling substantially simultaneous printing of both sides of a sheet of paper. 
     Optionally the device is configured to enable printing of standard A4 or Letter sized sheets of paper. 
     Optionally the device is configured such that paper to be printed is fed manually into a paper path that directs the paper from a region adjacent the upper edge of the flat panel display, past the printhead for printing, then out of the device adjacent a lower edge of the flat panel display. 
     Optionally the device further includes a curved paper guide disposed, when the device is in use, beneath the flat panel display, such that the paper that has been printed is urged horizontally as it exits the device. 
     Optionally the flat panel display is of one of the following types:
         Liquid Crystal Display (LCD);   Organic Light Emitting Diode (OLED)   Field Emission Display (FED)   Plasma Display Panel (PDP)       

     In a third aspect the present invention provides a display device for use as a computer monitor, the display device comprising:
         a flat panel display for displaying images from a computer;   a printer, the printer including:   (a) a printer controller configured to receive print data in a compressed form, decompress the print data, and output dot data based on the decompressed print data;   (b) a pagewidth printhead for receiving the dot data and printing onto print media.       

     Optionally the printer includes at least two of the printheads, the printheads being disposed on either side of a path through which print media is fed for printing, thereby enabling substantially simultaneous printing of both sides of the print media. 
     Optionally the device is configured to receive the print data, and display data to be displayed, from a computer system. 
     Optionally the printer controller is configured to halftone at least some of the decompressed print data as part of generating the dot data. 
     Optionally the printer controller is configured to composite text data with the halftoned data as part of generating the dot data. 
     Optionally the printer controller is configured to decompress both losslessly and lossily compressed print data. 
     Optionally the printer controller is configured to halftone the decompressed lossily compressed print data. 
     Optionally the printer controller is configured to composite the halftoned print data with the decompressed losslessly compressed print data as part of generating the dot data. 
     Optionally the printing and display device includes a connection configured to allow releasable operative connection of the computer system to the printing and display device, for receiving the print data and the display data from the computer system. 
     Optionally the connection includes at least one socket for accepting at least one corresponding data cable. 
     Optionally the connection includes a wireless receiver for receiving the print data and/or the display data. 
     Optionally the connection is a Universal Synchronous Bus (USB) connection. 
     Optionally the device further includes a paper feed mechanism for feeding paper to the printhead for printing, the printhead being arranged to print onto the paper. 
     Optionally the paper feed mechanism is configured to position the paper substantially parallel in at least one direction with respect to a plane defined by the flat panel display. 
     Optionally the paper feed mechanism is configured to accept a single sheet of paper at a time for printing. 
     Optionally the paper feed mechanism includes a paper separator for feeding a single sheet of paper to the printhead from a stack of sheets of paper. 
     Optionally the printer is a process color printer. 
     Optionally the printer is an inkjet printer. 
     Optionally the printer has more than 5,000 inkjet nozzles. 
     Optionally the flat panel display measures at least 14 inches on the diagonal. 
     Optionally the device further includes at least two of the printheads, the printheads being disposed on either side of a path through which the paper is fed for printing, thereby enabling substantially simultaneous printing of both sides of a sheet of paper. 
     Optionally the device is configured to enable printing of standard A4 or Letter sized sheets of paper. 
     Optionally the device is configured such that paper to be printed is fed manually into a paper path that directs the paper from a region adjacent the upper edge of the flat panel display, past the printhead for printing, then out of the device adjacent a lower edge of the flat panel display. 
     Optionally the device further includes a curved paper guide disposed, when the device is in use, beneath the flat panel display, such that the paper that has been printed is urged horizontally as it exits the device. 
     Optionally the flat panel display is of one of the following types:
         Liquid Crystal Display (LCD);   Organic Light Emitting Diode (OLED)   Field Emission Display (FED)   Plasma Display Panel (PDP)       

     In a fourth aspect the present invention provides a display device for use as a computer monitor, the display device comprising:
         a flat panel display;   a printer, including a printhead for printing onto paper; and   a print media print path along which print media is supplied to the printer, wherein at least a majority of the print path is in a plane that is substantially parallel to a plane defined by the flat panel display.       

     Optionally the device is configured such that print media to be printed passes between the flat panel display and the printhead. 
     Optionally the printhead is disposed adjacent a lower edge of the flat panel display. 
     Optionally the printhead is a pagewidth printhead that extends across a majority of the width of the device. 
     Optionally the device is configured such that print media to be printed passes behind the flat panel display and the printhead relative to a viewing position of the flat panel display. 
     Optionally the printhead is disposed adjacent a lower edge of the flat panel display. 
     Optionally the printhead is a pagewidth printhead that extends across a majority of the width of the device. 
     Optionally the device is configured to receive print data to be printed, and display data to be displayed on the flat panel display, from a computer system. 
     Optionally the device further includes a connection configured to allow releasable operative connection of the computer system to the display device, for receiving the print data and the display data from the computer system. 
     Optionally the connection includes at least one socket for accepting at least one corresponding data cable. 
     Optionally the connection includes a wireless receiver for receiving the print data and the display data. 
     Optionally the connection is a Universal Synchronous Bus (USB) connection. 
     Optionally the printer is a process color printer. 
     Optionally the printer is an inkjet printer. 
     Optionally the printer has more than 5,000 inkjet nozzles. 
     Optionally the printer is a page-width printer. 
     Optionally the flat panel display measures at least 14 cm on the diagonal. 
     In a fifth aspect the present invention provides a display device for use as a computer monitor, the display device comprising:
         a flat panel display;   a printer, including a printhead for printing onto paper; and   a sheet feeder for feeding print media to the printhead, the device being configured such that standard print media to be printed is supported, immediately prior to commencement of printing, such that at least an edge of the print media is visible above an upper edge of a the flat panel display.       

     Optionally the device further includes a print path along which the print media is supplied to the printer, wherein at least a majority of the print path is in a plane that is substantially parallel to a plane defined by the flat panel display. 
     Optionally the device is configured such that print media to be printed passes between the flat panel display and the printhead. 
     Optionally the printhead is disposed adjacent a lower edge of the flat panel display. 
     Optionally the printhead is a pagewidth printhead that extends across a majority of the width of the device. 
     Optionally the device is configured such that print media to be printed passes behind the flat panel display and the printhead relative to a viewing position of the flat panel display. 
     Optionally the printhead is disposed adjacent a lower edge of the flat panel display. 
     Optionally the printhead is a pagewidth printhead that extends across a majority of the width of the device. 
     Optionally the device is configured to receive print data to be printed, and display data to be displayed on the flat panel display, from a computer system. 
     Optionally the device further includes a connection configured to allow releasable operative connection of the computer system to the display device, for receiving the print data and the display data from the computer system. 
     Optionally the connection includes at least one socket for accepting at least one corresponding data cable. 
     Optionally the connection includes a wireless receiver for receiving the print data and the display data. 
     Optionally the connection is a Universal Synchronous Bus (USB) connection. 
     Optionally the printer is a process color printer. 
     Optionally the printer is an inkjet printer. 
     Optionally the printer has more than 5,000 inkjet nozzles. 
     Optionally the printer is a page-width printer. 
     Optionally the flat panel display measures at least 14 cm on the diagonal. 
     In a sixth aspect the present invention provides a display device for use as a computer monitor, the display device comprising:
         a flat panel display for displaying images from a computer, the flat panel defining a plane;   a printer, including a pagewidth printhead for printing onto print media; and   a print media print path along which print media is supplied to the printer, wherein at least a majority of the print path is parallel to the plane in at least one direction.       

     Optionally the device further includes a paper feed mechanism configured to accept a single sheet of paper at a time for printing, the paper feed mechanism being positioned in the paper path. 
     Optionally the paper feed mechanism includes a paper separator for feeding a single sheet of paper to the printhead from a stack of sheets of paper. 
     Optionally the device is configured to receive print data to be printed, and display data to be displayed on the flat panel display, from a computer system. 
     Optionally the device further includes a connection configured to allow releasable operative connection of the computer system to the display device, for receiving the print data and the display data from the computer system. 
     Optionally the connection includes at least one socket for accepting at least one corresponding data cable. 
     Optionally the connection includes a wireless receiver for receiving the print data and the display data. 
     Optionally the connection is a Universal Synchronous Bus (USB) connection. 
     Optionally the printer is a process color printer. 
     Optionally the printer is an inkjet printer. 
     Optionally the printer has more than 5,000 inkjet nozzles. 
     Optionally the printer is a page-width printer. 
     Optionally the flat panel display measures at least 14 cm on the diagonal. 
     In a seventh aspect the present invention provides a display device for use as a computer monitor, the display device comprising:
         a flat panel display for displaying images received from a computer system; and   a printer, the printer including a pagewidth printhead for printing onto print media, the pagewidth printhead extending across a majority of the width of the device.       

     Optionally the device further includes a print media feed mechanism for feeding print media to the printhead for printing. 
     Optionally the print media feed mechanism is configured to position the paper substantially parallel in at least one direction with respect to a plane defined by the flat panel display. 
     Optionally the print media feed mechanism is configured to accept a single sheet of paper at a time for printing. 
     Optionally the print media feed mechanism includes a paper separator for feeding a single sheet of paper to the printhead from a stack of sheets of paper. 
     Optionally the printing and display device includes a connection configured to allow releasable operative connection of the computer system to the printing and display device, for receiving the print data and the display data from the computer system. 
     Optionally the connection includes at least one socket for accepting at least one corresponding data cable. 
     Optionally the connection includes a wireless receiver for receiving the print data and/or the display data. 
     Optionally the connection is a Universal Synchronous Bus (USB) connection. 
     Optionally the printer is a process color printer. 
     Optionally the printer is an inkjet printer. 
     Optionally the printer has more than 5,000 inkjet nozzles. 
     Optionally the flat panel display measures at least 14 inches on the diagonal. 
     Optionally the device further includes at least two of the printheads, the printheads being disposed on either side of a path through which the paper is fed for printing, thereby enabling substantially simultaneous printing of both sides of a sheet of paper. 
     Optionally the device is configured to enable printing of standard A4 or Letter sized sheets of paper. 
     Optionally the device is configured such that paper to be printed is fed manually into a paper path that directs the paper from a region adjacent the upper edge of the flat panel display, past the printhead for printing, then out of the device adjacent a lower edge of the flat panel display. 
     Optionally the device further includes a curved paper guide disposed, when the device is in use, beneath the flat panel display, such that the paper that has been printed is urged horizontally as it exits the device. 
     Optionally the flat panel display is of one of the following types:
         Liquid Crystal Display (LCD);   Organic Light Emitting Diode (OLED)   Field Emission Display (FED)   Plasma Display Panel (PDP)       

     In an eighth aspect the present invention provides a display device for use as a computer monitor, the display device comprising:
         a flat panel display for displaying images received from a computer; and   a printer, the printer including a pagewidth printhead for printing onto print media, the printhead being disposed adjacent a lower portion of the display device.       

     Optionally the device further includes a print media feed mechanism for feeding print media to the printhead for printing. 
     Optionally the print media feed mechanism is configured to position the paper substantially parallel in at least one direction with respect to a plane defined by the flat panel display. 
     Optionally the print media feed mechanism is configured to accept a single sheet of paper at a time for printing. 
     Optionally the print media feed mechanism includes a paper separator for feeding a single sheet of paper to the printhead from a stack of sheets of paper. 
     Optionally the printing and display device includes a connection configured to allow releasable operative connection of the computer system to the printing and display device, for receiving the print data and the display data from the computer system. 
     Optionally the connection includes at least one socket for accepting at least one corresponding data cable. 
     Optionally the connection includes a wireless receiver for receiving the print data and/or the display data. 
     Optionally the connection is a Universal Synchronous Bus (USB) connection. 
     Optionally the printer is a process color printer. 
     Optionally the printer is an inkjet printer. 
     Optionally the printer has more than 5,000 inkjet nozzles. 
     Optionally the flat panel display measures at least 14 inches on the diagonal. 
     Optionally the device further includes at least two of the printheads, the printheads being disposed on either side of a path through which the paper is fed for printing, thereby enabling substantially simultaneous printing of both sides of a sheet of paper. 
     Optionally the device is configured to enable printing of standard A4 or Letter sized sheets of paper. 
     Optionally the device is configured such that paper to be printed is fed manually into a paper path that directs the paper from a region adjacent the upper edge of the flat panel display, past the printhead for printing, then out of the device adjacent a lower edge of the flat panel display. 
     Optionally the device further includes a curved paper guide disposed, when the device is in use, beneath the flat panel display, such that the paper that has been printed is urged horizontally as it exits the device. 
     Optionally the flat panel display is of one of the following types:
         Liquid Crystal Display (LCD);   Organic Light Emitting Diode (OLED)   Field Emission Display (FED)   Plasma Display Panel (PDP)       

     The invention will be more fully understood from the following description of an embodiment of a printing and display device that incorporates an exemplified form of the invention. The description is provided with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic of document data flow in a printing system; 
         FIG. 2  is a more detailed schematic showing an architecture used in the printing system of  FIG. 1 ; 
         FIG. 3  is a data representation of page element used in the printing system of  FIG. 1 , 
         FIG. 4  is a schematic showing CMOS drive and control blocks for use with the printer of  FIG. 1 ; 
         FIG. 5  is a schematic showing the relationship between nozzle columns and dot shift registers in the CMOS blocks of  FIG. 4 ; 
         FIG. 6  is a more detailed schematic showing a unit cell and its relationship to the nozzle columns and dot shift registers of  FIG. 5 ; 
         FIG. 7  is a circuit diagram showing logic for a single printer nozzle in the printer of  FIG. 1 ; 
         FIG. 8  is a perspective view of a flat panel display incorporating a printer, in accordance with the invention; 
         FIG. 9  is a perspective view of the flat panel display of  FIG. 8 , whilst printing a page; 
         FIG. 10  is a rear perspective view of the flat panel display of  FIG. 8 ; 
         FIG. 11  is a front elevation of the flat panel display of  FIG. 9 ; 
         FIG. 12  is a right-hand side elevation of the flat panel display of  FIG. 9 ; 
         FIG. 13  is a plan view of the flat panel display of  FIG. 9 ; 
         FIG. 14  is a left-hand side elevation of the flat panel display of  FIG. 9 ; 
         FIG. 15  is a rear elevation of the flat panel display of  FIG. 9 ; 
         FIG. 16  is a perspective exploded view of the flat panel display of  FIG. 8 ; 
         FIG. 17  is a rear perspective view of the flat panel display of  FIG. 8  with the stand detached; 
         FIG. 18  is a rear perspective view of the flat panel display of  FIG. 8  with the rear cover removed; 
         FIG. 19  is a rear perspective view of the flat panel display of  FIG. 8  with the shields removed; 
         FIG. 20  is a rear perspective view of the flat panel display of  FIG. 8  showing the core electrical and electronic components; 
         FIG. 21  is a perspective view of interconnected printed circuit boards used in the flat panel display of  FIG. 8 ; 
         FIG. 22  is a perspective view of the print engine used in the flat panel display of  FIG. 8 ; 
         FIG. 23  is a perspective view of the print engine of  FIG. 22 , with some componentry removed to reveal the printhead; 
         FIG. 24  is a vertical section along the centerline of the flat panel display of  FIG. 8 ; 
         FIG. 25  is an enlarged detail view of the vertical section of  FIG. 24 ; 
         FIG. 26  is an enlarged detail view of a vertical section of a second embodiment of a flat panel display incorporating a duplex printhead, in accordance with the invention; 
         FIG. 27  is a vertical section along the centerline of a third embodiment of a flat panel display incorporating a multi-sheet paper feeder, in accordance with the invention; 
         FIG. 28  is an enlarged detail view of the vertical section of  FIG. 27   
         FIG. 29  is a rear perspective view of an alternative embodiment of a flat panel display including power and data connections in its base, in accordance with the invention; 
         FIG. 30  is a rear perspective view of an alternative embodiment of a flat panel display including a power input, data inputs and data outputs in its base, in accordance with the invention; 
         FIG. 31  is a rear perspective view of an alternative embodiment of a flat panel display including power and data connections in its base and an ink cartridge in its mounting plate, in accordance with the invention; 
         FIG. 32  is a rear perspective view of an alternative embodiment of a flat panel display including an ink cartridge, a power input and data connections in its base, in accordance with the invention; 
         FIG. 33  is a perspective view of a bi-lithic printhead for use in the flat panel display of  FIG. 8 ; 
         FIG. 34  is a rear perspective view of the bi-lithic printhead of  FIG. 33 ; 
         FIGS. 35(   a ) to  35 ( d ) show a side elevation, plan view, opposite side elevation and reverse plan view, respectively, of the bi-lithic printhead of  FIG. 33 ; 
         FIGS. 36 and 37  show enlarged end views of the bi-lithic printhead of  FIG. 33 ; 
         FIG. 38  shows an enlarged detail plan view of one end of the bi-lithic printhead of  FIG. 33 ; 
         FIG. 39  is a sectional view taken along line  45 - 45  in  FIG. 38 ; 
         FIG. 40  is an enlarged detail perspective view of one end of the bi-lithic printhead of  FIG. 33 ; 
         FIG. 41  is an enlarged detail perspective view of an opposite end of the bi-lithic printhead of  FIG. 33 ; 
         FIG. 42  is an exploded perspective view of the bi-lithic printhead of  FIG. 33 ; 
         FIG. 43  is a sectional view taken along line  49 - 49  in  FIG. 38 ; 
         FIG. 44  is a schematic view showing the components of the flat panel display of  FIG. 8 ; 
         FIG. 45  is a schematic view of a print engine chip incorporated in the flat panel display of  FIG. 8 ; 
         FIG. 46  is a vertical sectional view of a single nozzle for ejecting ink, for use with the invention, in a quiescent state; 
         FIG. 47  is a vertical sectional view of the nozzle of  FIG. 46  during an initial actuation phase; 
         FIG. 48  is a vertical sectional view of the nozzle of  FIG. 57  later in the actuation phase; 
         FIG. 49  is a perspective partial vertical sectional view of the nozzle of  FIG. 48 , at the actuation state shown in  FIG. 48 ; 
         FIG. 50  is a perspective vertical section of the nozzle of  FIG. 46 , with ink omitted; 
         FIG. 51  is a vertical sectional view of the of the nozzle of  FIG. 50 ; 
         FIG. 52  is a perspective partial vertical sectional view of the nozzle of  FIG. 46 , at the actuation state shown in  FIG. 47 ; 
         FIG. 53  is a plan view of the nozzle of  FIG. 46 ; 
         FIG. 54  is a plan view of the nozzle of  FIG. 46  with the lever arm and movable nozzle removed for clarity; 
         FIG. 55  is a perspective vertical sectional view of a part of a printhead chip incorporating a plurality of the nozzle arrangements of the type shown in  FIG. 46 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     As shown in  FIG. 1 , in the preferred embodiment, the printing aspect of the invention is embodied in an A4/Letter printer  100  that prints documents supplied by a computer system  102 . The computer system  102  is programmed to perform various steps involved in printing a document, including receiving the document (step  103 ), buffering it (step  104 ) and rasterizing it (step  106 ), and then compressing it (step  108 ) for transmission to the printer  100 . 
     The compressed, multi-layer page image is buffered (step  110 ) upon receipt in the printer  100 , then expanded (step  112 ). The expanded contone layer is dithered (step  114 ) and then the black layer from the expansion step is composited over the dithered contone layer (step  116 ). Coded data can also be rendered (step  118 ) to form an additional layer, to be printed (in the preferred form) using an infrared ink that is substantially invisible to the human eye. The black, dithered contone and infrared layers are combined (step  120 ) to form a page that is supplied to a printhead for printing (step  122 ). In the preferred embodiment, the printhead is a bi-lithic printhead configured to print in 6 colors in a pagewidth format, although the design can be adapted to print using any desired number of colors, and can be monolithic or require multiple substrates depending upon implementation. 
     The preferred embodiment divides printer data into a high-resolution bi-level mask layer for text and line art and a medium-resolution contone color image layer for images or background colors. Optionally, colored text can be supported by the addition of a medium-to-high-resolution contone texture layer for texturing text and line art with color data taken from an image or from flat colors. The preferred printing architecture, elements of which are described in more detail below, generalises these contone layers by representing them in abstract “image” and “texture” layers which can refer to either image data or flat color data. This division of data into layers based on content follows the base mode Mixed Raster Content (MRC) model specified in ITU-T.44. Like the MRC base mode, the preferred printing architecture makes compromises in some cases when data to be printed overlap. In particular, in the preferred form all overlaps are reduced to a 3-layer representation in a process (collision resolution) embodying the compromises explicitly. 
     As shown in  FIG. 3 , the central data structure for the preferred printing architecture is a generalised representation of the three layers, called a page element. A page element can be used to represent units ranging from single rendered elements emerging from a rendering engine up to an entire band of a print job.  FIG. 3  shows a simplified UML diagram of a page element  300 . Conceptually, the bi-level symbol region selects between the two color sources, as described in more detail below. 
     Printing Architecture 
     A more detailed description of the printing architecture will now be described with reference to  FIGS. 2 and 3 . It will be appreciated that the components of the architecture  208  shown in  FIG. 2  will typically be device dependent, in that they process the data into a form required by a software or hardware component further downstream. 
     In  FIG. 2 , a renderer  209  exists outside of the more general printer system pipeline. Its purpose is to render files to be printed and deliver rendered elements to the data receiver  210  of the pipeline, using an API (“Application Programming Interface”) exposed by the data receiver  210  for that purpose. The rendered elements are delivered in order according to the painter&#39;s algorithm, which is well known to those skilled in the art of image processing. The data passed in through the API is converted by the data receiver  210  into lists of dictionaries and page elements for processing in later stages. 
     A collision resolver  211  accepts the simple page elements created by the data receiver and creates a fully opaque “resolved” page element for each intersection of a new element with the background and any elements already present. Fundamentally, the collision resolver guarantees that the entire page is tiled with opaque elements. 
     A stripper  212  divides a band of data into horizontally overlapping pieces. This need only be performed in the case where relatively wide or fast printers use multiple parallel devices in order to achieve the required output dot-rate. In such cases, each horizontally overlapping piece is fed into a corresponding device downstream. Where such data division is not required, the stripper  212  can be omitted. 
     Different printing configurations will require different configurations of layers for delivery to the downstream hardware. A layer reorganiser  213  converts 3-layer page elements to the appropriate 2- or 3-layer form for the specific configuration. Again, there may be cases in which this function is not required, in which case the layer organiser can be omitted. 
     A contone combiner  214  combines and clips the image and texture layers of all page elements in a strip into single image and texture layers, as required by downstream hardware. 
     A color converter  215  transforms the contone planes of all page elements from the input color space to a device-specific color space (which is usually CMYK). 
     A mask combiner  216  performs the same operation on the mask layer as the contone combiner performs on the contone layers. All elements are clipped to a strip boundary and drawn into a single mask buffer. 
     A densitometer  218  measures the density of the current page as a percentage of total possible density. This operation is necessary only in low-end printers with power supplies that may not be able to handle a fully dense page at full speed. 
     A contone compressor  220  compresses the contone layers of all page elements in order to reduce downstream memory and/or transmission bandwidth requirements. 
     A mask formatter  222  converts the mask layer of page elements, which may be represented as regions of placed symbol references, into the form expected by a downstream mask decompressor. 
     A size limiter  224  ensures that all size limitations, for bands and for entire pages, are adhered to, by either dividing bands into smaller bands or by recompressing the data, repeating until the constraint is satisfied. 
     If data is to be transmitted to the printer between pipeline stages, a serialised form of the data structures is generated (in serialiser  226 ), transmitted, then deserialised (in deserialiser  228 ). 
     Within the printer, a distributor  230  converts data from a proprietary representation into a hardware-specific representation and ensures that the data for each strip is sent to the correct hardware device whilst observing any constraints or requirements on data transmission to these devices. The distributor distributes the converted data to an appropriate one of a plurality of pipelines  232 . The pipelines are identical to each other, and in essence provide decompression, scaling and dot compositing functions to generate a set of printable dot outputs. 
     Each pipeline  232  includes a buffer  234  for receiving the data. A contone decompressor  236  decompresses the color contone planes, and a mask decompressor  238  decompresses the monotone (text) layer. Contone and mask scalers  240  and  242  scale the decompressed contone and mask planes respectively, to take into account the size of the medium onto which the page is to be printed. 
     The scaled contone planes are then dithered by ditherer  244 . In the preferred form, a stochastic dispersed-dot dither is used. Unlike a clustered-dot (or amplitude-modulated) dither, a dispersed-dot (or frequency-modulated) dither reproduces high spatial frequencies (i.e. image detail) almost to the limits of the dot resolution, while simultaneously reproducing lower spatial frequencies to their full color depth, when spatially integrated by the eye. A stochastic dither matrix is carefully designed to be relatively free of objectionable low-frequency patterns when tiled across the image. As such, its size typically exceeds the minimum size required to support a particular number of intensity levels (e.g. 16×16×8 bits for 257 intensity levels). 
     The dithered planes are then composited in a dot compositor  246  on a dot-by-dot basis to provide dot data suitable for printing. This data is forwarded to data distribution and drive circuitry  248 , which in turn distributes the data to the correct nozzle actuators  250 , which in turn cause ink to be ejected from the correct nozzles  252  at the correct time. This process is described in more detail below. 
     The architecture  208  includes a mainly software-based computer system portion prior to the serialiser  226 , and a mainly hardware-based printer portion that is located within a printer remote from the computer system, which includes everything from the deserialiser  228  onwards. It will be appreciated, however, that the indicated division between computer system and printer is somewhat arbitrary, and various components can be placed on different sides of the divide without substantially altering the operation of the architecture as a whole. It will also be appreciated that some of the components in the architecture  208  can be handled in hardware or software remotely from the main computer system and printer. For example, rather than relying on the general-purpose processor of a personal computer, some of the components in the architecture can be accelerated using dedicated hardware. 
     SoPEC Device 
     In the preferred form, the hardware pipelines  232  are embodied in a Small Office Home Office Printer Engine Controller (SoPEC), as shown in  FIG. 2  and described in more detail below. The printer preferably also includes one or more system on a chip (SoC) components, as well as the print engine pipeline control application specific logic, configured to perform some or all of the functions described above in relation to the printing pipeline. 
     As shown in  FIG. 45 , from the highest point of view a SoPEC device consists of 3 distinct subsystems: a Central Processing Unit (CPU) subsystem  301 , a Dynamic Random Access Memory (DRAM) subsystem  302  and a Print Engine Pipeline (PEP) subsystem  303 . 
     The CPU subsystem  301  includes a CPU  30  that controls and configures all aspects of the other subsystems. It provides general support for interfacing and synchronizing the external printer with the internal print engine. It also controls the low-speed communication to QA chips (which are described elsewhere in this specification). The CPU subsystem  301  also contains various peripherals to aid the CPU, such as General Purpose Input Output (GPIO, which includes motor control), an Interrupt Controller Unit (ICU), LSS Master and general timers. The Serial Communications Block (SCB) on the CPU subsystem provides a full speed USB1.1 interface to the host as well as an Inter SoPEC Interface (ISI) to other SoPEC devices (not shown). 
     The DRAM subsystem  302  accepts requests from the CPU, Serial Communications Block (SCB) and blocks within the PEP subsystem. The DRAM subsystem  302 , and in particular the DRAM Interface Unit (DIU), arbitrates the various requests and determines which request should win access to the DRAM. The DIU arbitrates based on configured parameters, to allow sufficient access to DRAM for all requestors. The DIU also hides the implementation specifics of the DRAM such as page size, number of banks and refresh rates. 
     The Print Engine Pipeline (PEP) subsystem  303  accepts compressed pages from DRAM and renders them to bi-level dots for a given print line destined for a printhead interface that communicates directly with up to 2 segments of a bi-lithic printhead. The first stage of the page expansion pipeline is the Contone Decoder Unit (CDU), Lossless Bi-level Decoder (LBD) and Tag Encoder (TE). The CDU expands the JPEG-compressed contone (typically CMYK) layers, the LBD expands the compressed bi-level layer (typically K), and the TE encodes Netpage tags for later rendering (typically in IR or K ink). The output from the first stage is a set of buffers: the Contone FIFO unit (CFU), the Spot FIFO Unit (SFU), and the Tag FIFO Unit (TFU). The CFU and SFU buffers are implemented in DRAM. 
     The second stage is the Halftone Compositor Unit (HCU), which dithers the contone layer and composites position tags and the bi-level spot layer over the resulting bi-level dithered layer. 
     A number of compositing options can be implemented, depending upon the printhead with which the SoPEC device is used. Up to 6 channels of bi-level data are produced from this stage, although not all channels may be present on the printhead. For example, the printhead may be CMY only, with K pushed into the CMY channels and IR ignored. Alternatively, the encoded tags may be printed in K if IR ink is not available (or for testing purposes). 
     In the third stage, a Dead Nozzle Compensator (DNC) compensates for dead nozzles in the printhead by color redundancy and error diffusing of dead nozzle data into surrounding dots. 
     The resultant bi-level 6 channel dot-data (typically CMYK, Infrared, Fixative) is buffered and written to a set of line buffers stored in DRAM via a Dotline Writer Unit (DWU). 
     Finally, the dot-data is loaded back from DRAM, and passed to the printhead interface via a dot FIFO. The dot FIFO accepts data from a Line Loader Unit (LLU) at the system clock rate (pc/k), while the PrintHead Interface (PHI) removes data from the FIFO and sends it to the printhead at a rate of ⅔ times the system clock rate. 
     In the preferred form, the DRAM is 2.5 Mbytes in size, of which about 2 Mbytes are available for compressed page store data. A compressed page is received in two or more bands, with a number of bands stored in memory. As a band of the page is consumed by the PEP subsystem  303  for printing, a new band can be downloaded. The new band may be for the current page or the next page. 
     Using banding it is possible to begin printing a page before the complete compressed page is downloaded, but care must be taken to ensure that data is always available for printing or a buffer under-run may occur. 
     The embedded USB 1.1 device accepts compressed page data and control commands from the host PC, and facilitates the data transfer to either the DRAM (or to another SoPEC device in multi-SoPEC systems, as described below). 
     Multiple SoPEC devices can be used in alternative embodiments, and can perform different functions depending upon the particular implementation. For example, in some cases a SoPEC device can be used simply for its onboard DRAM, while another SoPEC device attends to the various decompression and formatting functions described above. This can reduce the chance of buffer under-run, which can happen in the event that the printer commences printing a page prior to all the data for that page being received and the rest of the data is not received in time. 
     Adding an extra SoPEC device for its memory buffering capabilities doubles the amount of data that can be buffered, even if none of the other capabilities of the additional chip are utilized. 
     Each SoPEC system can have several quality assurance (QA) devices designed to cooperate with each other to ensure the quality of the printer mechanics, the quality of the ink supply so the printhead nozzles will not be damaged during prints, and the quality of the software to ensure printheads and mechanics are not damaged. 
     Normally, each printing SoPEC will have an associated printer QA, which stores information printer attributes such as maximum print speed. An ink cartridge for use with the system will also contain an ink QA chip, which stores cartridge information such as the amount of ink remaining. The printhead also has a QA chip, configured to act as a ROM (effectively as an EEPROM) that stores printhead-specific information such as dead nozzle mapping and printhead characteristics. The CPU in the SoPEC device can optionally load and run program code from a QA Chip that effectively acts as a serial EEPROM. Finally, the CPU in the SoPEC device runs a logical QA chip (ie, a software QA chip). 
     Usually, all QA chips in the system are physically identical, with only the contents of flash memory differentiating one from the other. 
     Each SoPEC device has two LSS system buses that can communicate with QA devices for system authentication and ink usage accounting. A large number of QA devices can be used per bus and their position in the system is unrestricted with the exception that printer QA and ink QA devices should be on separate LSS busses. 
     In use, the logical QA communicates with the ink QA to determine remaining ink. The reply from the ink QA is authenticated with reference to the printer QA. The verification from the printer QA is itself authenticated by the logical QA, thereby indirectly adding an additional authentication level to the reply from the ink QA. 
     Data passed between the QA chips, other than the printhead QA, is authenticated by way of digital signatures. In the preferred embodiment, HMAC-SHA1 authentication is used for data, and RSA is used for program code, although other schemes could be used instead. 
     A single SoPEC device can control two bi-lithic printheads and up to six color channels. Six channels of colored ink are the expected maximum in a consumer SOHO, or office bi-lithic printing environment, and include:
         CMY (cyan, magenta, yellow), for regular color printing.   K (black), for black text, line graphics and gray-scale printing.   IR (infrared), for Netpage-enabled applications.   F (fixative), to enable printing at high speed.       

     Because the bi-lithic printer is capable of printing so fast, a fixative may be required to enable the ink to dry before the page touches the page already printed. Otherwise ink may bleed between pages. In relatively low-speed printing environments the fixative may not be required. 
     In the preferred form, the SoPEC device is color space agnostic. Although it can accept contone data as CMYX or RGBX, where X is an optional 4th channel, it also can accept contone data in any print color space. Additionally, SoPEC provides a mechanism for arbitrary mapping of input channels to output channels, including combining dots for ink optimization and generation of channels based on any number of other channels. However, inputs are typically CMYK for contone input, K for the bi-level input, and the optional Netpage tag dots are typically rendered to an infrared layer. A fixative channel is typically generated for fast printing applications. 
     In the preferred form, the SoPEC device is also resolution agnostic. It merely provides a mapping between input resolutions and output resolutions by means of scale factors. The expected output resolution for the preferred embodiment is 1600 dpi, but SoPEC actually has no knowledge of the physical resolution of the Bi-lithic printhead. 
     In the preferred form, the SoPEC device is page-length agnostic. Successive pages are typically split into bands and downloaded into the page store as each band of information is consumed. 
     The following three tables show the constituents of each of the three distinct subsystems which make up the SoPEC device. In particular, each of the columns provide the unit acronym, the unit name and a description of the functions performed by each unit. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                   
                 Unit 
                   
                   
               
               
                 Subsystem 
                 Acronym 
                 Unit Name 
                 Description 
               
               
                   
               
             
            
               
                 DRAM 
                 DIU 
                 DRAM interface unit 
                 Provides interface for DRAM read 
               
               
                   
                   
                   
                 and write access for the various 
               
               
                   
                   
                   
                 SoPEC units, CPU and the SCB 
               
               
                   
                   
                   
                 block. The DIU provides arbitration 
               
               
                   
                   
                   
                 between competing units and controls 
               
               
                   
                   
                   
                 DRAM access. 
               
               
                   
                 DRAM 
                 Embedded DRAM 
                 20 Mbits of embedded DRAM. 
               
               
                 CPU 
                 CPU 
                 Central Processing Unit 
                 CPU for system configuration and 
               
               
                   
                   
                   
                 control. 
               
               
                   
                 MMU 
                 Memory Management Unit 
                 Limits access to certain memory 
               
               
                   
                   
                   
                 address areas in CPU user mode. 
               
               
                   
                 RDU 
                 Real-time Debug Unit 
                 Facilitates the observation of the 
               
               
                   
                   
                   
                 contents of most of the CPU 
               
               
                   
                   
                   
                 addressable registers in SoPEC, 
               
               
                   
                   
                   
                 in addition to some pseudo- 
               
               
                   
                   
                   
                 registers in real time 
               
               
                   
                 TIM 
                 General Timer 
                 Contains watchdog and general 
               
               
                   
                   
                   
                 system timers 
               
               
                   
                 LSS 
                 Low Speed Serial 
                 Low level controller for 
               
               
                   
                   
                 Interfaces 
                 interfacing with QA chips 
               
               
                   
                 GPIO 
                 General Purpose IOs 
                 General IO controller, with built- 
               
               
                   
                   
                   
                 in Motor control unit, LED pulse 
               
               
                   
                   
                   
                 units and de-glitch circuitry 
               
               
                   
                 ROM 
                 Boot ROM 
                 16 KBytes of System Boot ROM 
               
               
                   
                   
                   
                 code 
               
               
                   
                 ICU 
                 Interrupt Controller Unit 
                 General Purpose interrupt 
               
               
                   
                   
                   
                 controller with configurable 
               
               
                   
                   
                   
                 priority, and masking. 
               
               
                   
                 CPR 
                 Clock, Power and Reset 
                 Central Unit for controlling and 
               
               
                   
                   
                 block 
                 generating the system clocks and 
               
               
                   
                   
                   
                 resets and powerdown mechanisms 
               
               
                   
                 PSS 
                 Power Save Storage 
                 Storage retained while system is 
               
               
                   
                   
                   
                 powered down 
               
               
                   
                 USB 
                 Universal Serial Bus 
                 USB device controller for 
               
               
                   
                   
                 Device 
                 interfacing with the host USB. 
               
               
                   
                 ISI 
                 Inter-SoPEC Interface 
                 ISI controller for data and 
               
               
                   
                   
                   
                 control communication with 
               
               
                   
                   
                   
                 other SoPECs in a multi-SoPEC 
               
               
                   
                   
                   
                 system 
               
               
                   
                 SCB 
                 Serial Communication 
                 Contains both the USB and ISI 
               
               
                   
                   
                 Block 
                 blocks. 
               
               
                 Print 
                 PCU 
                 PEP controller 
                 Provides external CPU with the 
               
               
                 Engine 
                   
                   
                 means to read and write PEP Unit 
               
               
                 Pipeline 
                   
                   
                 registers, and read and write DRAM 
               
               
                 (PEP) 
                   
                   
                 in single 32-bit chunks. 
               
               
                   
                 CDU 
                 Contone Decoder Unit 
                 Expands JPEG compressed contone 
               
               
                   
                   
                   
                 layer and writes decompressed 
               
               
                   
                   
                   
                 contone to DRAM 
               
               
                   
                 CFU 
                 Contone FIFO Unit 
                 Provides line buffering between 
               
               
                   
                   
                   
                 CDU and HCU 
               
               
                   
                 LBD 
                 Lossless Bi-level 
                 Expands compressed bi-level layer. 
               
               
                   
                   
                 Decoder 
               
               
                   
                 SFU 
                 Spot FIFO Unit 
                 Provides line buffering between 
               
               
                   
                   
                   
                 LBD and HCU 
               
               
                   
                 TE 
                 Tag Encoder 
                 Encodes tag data into line of tag 
               
               
                   
                   
                   
                 dots. 
               
               
                   
                 TFU 
                 Tag FIFO Unit 
                 Provides tag data storage between 
               
               
                   
                   
                   
                 TE and HCU 
               
               
                   
                 HCU 
                 Halftoner Compositor 
                 Dithers contone layer and 
               
               
                   
                   
                 Unit 
                 composites the bi-level spot and 
               
               
                   
                   
                   
                 position tag dots. 
               
               
                   
                 DNC 
                 Dead Nozzle 
                 Compensates for dead nozzles by 
               
               
                   
                   
                 Compensator 
                 color redundancy and error diffusing 
               
               
                   
                   
                   
                 dead nozzle data into surrounding dots. 
               
               
                   
                 DWU 
                 Dotline Writer Unit 
                 Writes out the 6 channels of dot data 
               
               
                   
                   
                   
                 for a given printline to the line 
               
               
                   
                   
                   
                 store DRAM 
               
               
                   
                 LLU 
                 Line Loader Unit 
                 Reads the expanded page image 
               
               
                   
                   
                   
                 from line store, formatting the data 
               
               
                   
                   
                   
                 appropriately for the bi-lithic 
               
               
                   
                   
                   
                 printhead. 
               
               
                   
                 PHI 
                 PrintHead Interface 
                 Responsible for sending dot data to 
               
               
                   
                   
                   
                 the bi-lithic printheads and for 
               
               
                   
                   
                   
                 providing line synchronization between 
               
               
                   
                   
                   
                 multiple SoPECs. Also provides test 
               
               
                   
                   
                   
                 interface to printhead such as 
               
               
                   
                   
                   
                 temperature monitoring and Dead 
               
               
                   
                   
                   
                 Nozzle Identification. 
               
               
                   
               
            
           
         
       
     
     Printhead Mechanical 
     In the preferred form, a Memjet printer has two printhead integrated circuits that are mounted adjacent each other to form a pagewidth printhead. Typically, the printhead ICs can vary in size from 2 inches to 8 inches, so several combinations can be used to produce, say, an A4 pagewidth printhead. For example two printhead ICs of 7 and 3 inches, 2 and 4 inches, or 5 and 5 inches could be used to create an A4 printhead (the notation is 7:3). Similarly 6 and 4 (6:4) or 5 and 5 (5:5) combinations can be used. An A3 printhead can be constructed from 8 and 6-inch printhead integrated circuits, for example. For photographic printing, particularly in camera, smaller printheads can be used. It will also be appreciated that a single printhead integrated circuit, or more than two such circuits, can also be used to achieve the required printhead width. 
     A preferred printhead embodiment will now be described with reference to  FIGS. 33 to 43 . As best shown in  FIGS. 33 to 35  and  FIG. 42 , a printhead  420  takes the form of an elongate unit. As best shown in  FIG. 42 , the components of the printhead  420  include a support member  421 , a flexible PCB  422 , an ink distribution molding  423 , an ink distribution plate  424 , a MEMS printhead comprising first and second printhead integrated circuits (ICs)  425  and  426 , and busbars  427 . 
     The support member  421  is can be formed from any suitable material, such as metal or plastic, and can be extruded, molded or formed in any other way. The support member  421  should be strong enough to hold the other components in the appropriate alignment relative to each other whilst stiffening and strengthening the printhead as a whole. 
     The flexible PCB extends the length of the printhead  420  and includes first and second electrical connectors  428  and  429 . The electrical connectors  428  and  429  correspond with the flexible connectors  147  shown  FIG. 22 . The electrical connectors include contact areas  148  and  159  that, in use, are positioned in contact with corresponding output connectors (not shown) from the SoPEC chip  166  ( FIG. 21 ). Data from the SoPEC chip  166  passes along the electrical connectors  428  and  429 , and is distributed to respective ends of the first and second printhead ICs  425  and  426 . 
     As shown in  FIG. 43 , the ink distribution molding  423  includes a plurality of elongate conduits  430  that distribute fluids (ie, colored inks, infrared ink and fixative) and pressurized air from the air pump along the length of the printhead  420  ( FIG. 42 ). Sets of fluid apertures  431  ( FIG. 39 ) disposed along the length of the ink distribution molding  423  distribute the fluids and air from the conduits  430  to the ink distribution plate  424 . The fluids and air are supplied via nozzles  440  formed on a plug  441  ( FIG. 35 ), which plugs into a corresponding socket (not shown) in the printer. 
     The distribution plate  424  is a multi-layer construction configured to take fluids provided locally from the fluid apertures  431  and distribute them through smaller distribution apertures  432  into the printhead ICs  425  and  426  (as shown in  FIG. 39 ). 
     The printhead ICs  425  and  426  are positioned end to end, and are held in contact with the distribution plate  424  so that ink from the smaller distribution apertures  432  can be fed into corresponding apertures (not shown) in the printhead ICs  425  and  426 . 
     The busbars  427  are relatively high-capacity conductors positioned to provide drive current to the actuators of the printhead nozzles (described in detail below). As best shown in  FIGS. 39 to 41 , the busbars  427  are retained in position at one end by a socket  433 , and at both ends by wrap-around wings  434  of the flexible PCB  422 . The busbars also help hold the printhead ICs  425  in position, as best shown in  FIGS. 38 ,  40  and  41 . 
     As shown best in  FIGS. 40 ,  41  and  42 , when assembled, the flexible PCB  422  is effectively wrapped around the other components, thereby holding them in contact with each other. Notwithstanding this binding effect, the support member  421  provides a major proportion of the required stiffness and strength of the printhead  420  as a whole. 
     Printhead CMOS 
     Turning now to  FIGS. 4 to 7 , a preferred embodiment of the printhead  420  (comprising printhead ICs  425  and  426 ) will be described. For clarity, only one printhead IC  425  is shown in  FIG. 4 , but it will be appreciated that a corresponding arrangement is implemented for the printhead IC  426 . 
       FIG. 4  shows an overview of printhead IC  425  and its connections to the SoPEC device  166 . Printhead IC  425  includes a nozzle core array  401  containing the repeated logic to fire each nozzle, and nozzle control logic  402  to generate the timing signals to fire the nozzles. The nozzle control logic  402  receives data from the SoPEC chip  166  via a high-speed link. In the preferred form, a single SoPEC chip  166  feeds the two printhead ICs  425  and  426  with print data. 
     The nozzle control logic  402  is configured to send serial data to the nozzle array core for printing, via a link  407 , which for printhead  425  is the electrical connector  428 . Status and other operational information about the nozzle array core  401  is communicated back to the nozzle control logic via another link  408 , which is also provided on the electrical connector  428 . 
     The nozzle array core  401  is shown in more detail in  FIGS. 5 and 6 . In  FIG. 5 , it will be seen that the nozzle array core comprises an array of nozzle columns  501 . The array includes a fire/select shift register  502  and up to 6 color channels, each of which is represented by a corresponding dot shift register  503 . 
     As shown in  FIG. 6 , the fire/select shift register  502  includes forward path fire shift register  600 , a reverse path fire shift register  601  and a select shift register  602 . Each dot shift register  503  includes an odd dot shift register  603  and an even dot shift register  604 . The odd and even dot shift registers  603  and  604  are connected at one end such that data is clocked through the odd shift register  603  in one direction, then through the even shift register  604  in the reverse direction. The output of all but the final even dot shift register is fed to one input of a multiplexer  605 . This input of the multiplexer is selected by a signal (corescan) during post-production testing. In normal operation, the corescan signal selects dot data input Dot[x] supplied to the other input of the multiplexer  605 . This causes Dot[x] for each color to be supplied to the respective dot shift registers  503 . 
     A single column N will now be described with reference to  FIG. 6 . In the embodiment shown, the column N includes 12 data values, comprising an odd data value  606  and an even data value  607  for each of the six dot shift registers. Column N also includes an odd fire value  608  from the forward fire shift register  600  and an even fire value  609  from the reverse fire shift register  601 , which are supplied as inputs to a multiplexer  610 . The output of the multiplexer  610  is controlled by the select value  611  in the select shift register  602 . When the select value is zero, the odd fire value is output, and when the select value is one, the even fire value is output. 
     Each of the odd and even data values  606  and  607  is provided as an input to corresponding odd and even dot latches  612  and  613  respectively. 
     Each dot latch and its associated data value form a unit cell, such as unit cell  614 . A unit cell is shown in more detail in  FIG. 7 . The dot latch  612  is a D-type flip-flop that accepts the output of the data value  606 , which is held by a D-type flip-flop  614  forming an element of the odd dot shift register  603 . The data input to the flip-flop  614  is provided from the output of a previous element in the odd dot shift register (unless the element under consideration is the first element in the shift register, in which case its input is the Dot[x] value). Data is clocked from the output of flip-flop  614  into latch  612  upon receipt of a negative pulse provided on LsyncL. 
     The output of latch  612  is provided as one of the inputs to a three-input AND gate  615 . Other inputs to the AND gate  615  are the Fr signal (from the output of multiplexer  610 ) and a pulse profile signal Pr. The firing time of a nozzle is controlled by the pulse profile signal Pr, and can be, for example, lengthened to take into account a low voltage condition that arises due to low battery (in a battery-powered embodiment). This is to ensure that a relatively consistent amount of ink is efficiently ejected from each nozzle as it is fired. In the embodiment described, the profile signal Pr is the same for each dot shift register, which provides a balance between complexity, cost and performance. However, in other embodiments, the Pr signal can be applied globally (ie, is the same for all nozzles), or can be individually tailored to each unit cell or even to each nozzle. 
     Once the data is loaded into the latch  612 , the fire enable Fr and pulse profile Pr signals are applied to the AND gate  615 , combining to the trigger the nozzle to eject a dot of ink for each latch  612  that contains a logic 1. 
     The signals for each nozzle channel are summarized in the following table: 
     
       
         
           
               
               
               
             
               
                   
               
               
                 Name 
                 Direction 
                 Description 
               
               
                   
               
             
            
               
                 d 
                 Input 
                 Input dot pattern to shift register bit 
               
               
                 q 
                 Output 
                 Output dot pattern from shift register bit 
               
               
                 SrClk 
                 Input 
                 Shift register clock in - d is captured on rising 
               
               
                   
                   
                 edge of this clock 
               
               
                 LsyncL 
                 Input 
                 Fire enable - needs to be asserted for nozzle to fire 
               
               
                 Pr 
                 Input 
                 Profile - needs to be asserted for nozzle to fire 
               
               
                   
               
            
           
         
       
     
     As shown in  FIG. 7 , the fire signals Fr are routed on a diagonal, to enable firing of one color in the current column, the next color in the following column, and so on. This averages the current demand by spreading it over 6 columns in time-delayed fashion. 
     The dot latches and the latches forming the various shift registers are fully static in this embodiment, and are CMOS-based. The design and construction of latches is well known to those skilled in the art of integrated circuit engineering and design, and so will not be described in detail in this document. 
     The combined printhead ICs define a printhead having 13824 nozzles per color. Therefore, in the case where the printhead ICs  425  and  426  are equal in length, each of them includes 6912 nozzles per color. The circuitry supporting each nozzle is the same, but the pairing of nozzles happens due to physical positioning of the MEMS nozzles; odd and even nozzles are not actually on the same horizontal line 
     Power and ground are provided via pads disposed along the length of the printhead ICs. The pads are connected to busbars  427  using conductive adhesive, as described above. 
     Printhead Nozzles and Actuators 
     The preferred printhead nozzle arrangement, comprising a nozzle and corresponding actuator, will now be described with reference to  FIGS. 46 to 55 .  FIG. 47  shows an array of the nozzle arrangements  801  formed on a silicon substrate  8015 . The nozzle arrangements are identical, but in the preferred embodiment, different nozzle arrangements are fed with different colored inks and fixative. It will be noted that rows of the nozzle arrangements  801  are staggered with respect to each other, allowing closer spacing of ink dots during printing than would be possible with a single row of nozzles. The multiple rows also allow for redundancy (if desired), thereby allowing for a predetermined failure rate per nozzle. 
     Each nozzle arrangement  801  is the product of an integrated circuit fabrication technique. In particular, the nozzle arrangement  801  defines a micro-electromechanical system (MEMS). 
     For clarity and ease of description, the construction and operation of a single nozzle arrangement  801  will be described with reference to  FIGS. 46 to 54 . 
     Each of the ink jet printhead chips  425 ,  426  includes a silicon wafer substrate  801 . 0.35 Micron 1 P4M 12 volt CMOS microprocessing circuitry is positioned on the silicon wafer substrate  8015 . 
     A silicon dioxide (or alternatively glass) layer  8017  is positioned on the wafer substrate  8015 . The silicon dioxide layer  8017  defines CMOS dielectric layers. CMOS top-level metal defines a pair of aligned aluminium electrode contact layers  8030  positioned on the silicon dioxide layer  8017 . Both the silicon wafer substrate  8015  and the silicon dioxide layer  8017  are etched to define an ink inlet channel  8014  having a generally circular cross section (in plan). An aluminium diffusion barrier  8028  of CMOS metal  1 , CMOS metal  2 / 3  and CMOS top level metal is positioned in the silicon dioxide layer  8017  about the ink inlet channel  8014 . The diffusion barrier  8028  serves to inhibit the diffusion of hydroxyl ions through CMOS oxide layers of the drive circuitry layer  8017 . 
     A passivation layer in the form of a layer of silicon nitride  8031  is positioned over the aluminium contact layers  8030  and the silicon dioxide layer  8017 . Each portion of the passivation layer  8031  positioned over the contact layers  8030  has an opening  8032  defined therein to provide access to the contacts  8030 . 
     The nozzle arrangement  801  includes a nozzle chamber  8029  defined by an annular nozzle wall  8033 , which terminates in a nozzle rim  804  that is circular in plan. The ink inlet channel  8014  is in fluid communication with the nozzle chamber  8029 . At a lower end of the nozzle wall, there is disposed a moving rim  8010 , that includes a moving seal lip  8040 . An encircling wall  8038  surrounds the movable nozzle, and includes a stationary seal lip  8039  that, when the nozzle is at rest as shown in  FIG. 46 , is adjacent the moving rim  8010 . A fluidic seal  8011  is formed due to the surface tension of ink trapped between the stationary seal lip  8039  and the moving seal lip  8040 . This prevents leakage of ink from the chamber whilst providing a low resistance coupling between the encircling wall  8038  and the nozzle wall  8033 . 
     As best shown in  FIG. 47 , a plurality of radially extending recesses  8035  is defined in the roof  8034  about the nozzle rim  804 . The recesses  8035  serve to contain radial ink flow as a result of ink escaping past the nozzle rim  804 . 
     The nozzle wall  8033  forms part of a lever arrangement that is mounted to a carrier  8036  having a generally U-shaped profile with a base  8037  attached to the layer  8031  of silicon nitride. 
     The lever arrangement also includes a lever arm  8018  that extends from the nozzle walls and incorporates a lateral stiffening beam  8022 . The lever arm  8018  is attached to a pair of passive beams  806 , formed from titanium nitride (TiN) and positioned on either side of the nozzle arrangement, as best shown in  FIGS. 49 and 54 . The other ends of the passive beams  806  are attached to the carrier  8036 . 
     The lever arm  8018  is also attached to an actuator beam  807 , which is formed from TiN. It will be noted that this attachment to the actuator beam is made at a point a small but critical distance higher than the attachments to the passive beam  806 . 
     As best shown in  FIGS. 49 and 52 , the actuator beam  807  is substantially U-shaped in plan, defining a current path between the electrode  809  and an opposite electrode  8041 . Each of the electrodes  809  and  8041  are electrically connected to respective points in the contact layer  8030  (shown in  FIGS. 46 and 51 ). As well as being electrically coupled via the contacts  809 , the actuator beam is also mechanically anchored to anchor  808 . The anchor  808  is configured to constrain motion of the actuator beam  807  to the left of  FIGS. 46 to 48  when the nozzle arrangement is in operation. 
     The TiN in the actuator beam  807  is conductive, but has a high enough electrical resistance that it undergoes self-heating when a current is passed between the electrodes  809  and  8041 . No current flows through the passive beams  806 , so they do not expand. 
     In use, the device at rest is filled with ink  8013  ( FIG. 46 ) that defines a meniscus  803  under the influence of surface tension. The ink is retained in the chamber  8029  by the meniscus, and will not generally leak out in the absence of some other physical influence. 
     As shown in  FIG. 47 , to fire ink from the nozzle, a current is passed between the contacts  809  and  8041 , passing through the actuator beam  807 . The self-heating of the beam  807  due to its resistance causes the beam to expand. The dimensions and design of the actuator beam  807  mean that the majority of the expansion in a horizontal direction with respect to  FIGS. 46 to 48 . The expansion is constrained to the left by the anchor  808 , so the end of the actuator beam  807  adjacent the lever arm  8018  is impelled to the right. 
     The relative horizontal inflexibility of the passive beams  806  prevents them from allowing much horizontal movement with respect to the lever arm  8018 . However, the relative displacement of the attachment points of the passive beams and actuator beam respectively to the lever arm causes a twisting movement that causes the lever arm  8018  to move generally downwards. The movement is effectively a pivoting or hinging motion. However, the absence of a true pivot point means that the rotation is about a pivot region defined by bending of the passive beams  806 . 
     The downward movement (and slight rotation) of the lever arm  8018  is amplified by the distance of the nozzle wall  8033  from the passive beams  806 . The downward movement of the nozzle walls and roof causes a pressure increase within the chamber  8029 , causing the meniscus to bulge as shown in  FIG. 47 . It will be noted that the surface tension of the ink means the fluid seal  8011  is stretched by this motion without allowing ink to leak out. 
     As shown in  FIG. 48 , at the appropriate time, the drive current is stopped and the actuator beam  807  quickly cools and contracts. The contraction causes the lever arm to commence its return to the quiescent position, which in turn causes a reduction in pressure in the chamber  8029 . The interplay of the momentum of the bulging ink and its inherent surface tension, and the negative pressure caused by the upward movement of the nozzle chamber  8029  causes thinning, and ultimately snapping, of the bulging meniscus to define an ink drop  802  that continues upwards until it contacts adjacent print media. 
     Immediately after the drop  802  detaches, the meniscus forms the concave shape shown in  FIG. 48 . Surface tension causes the pressure in the chamber  8029  to remain relatively low until ink has been sucked upwards through the inlet  8014 , which returns the nozzle arrangement and the ink to the quiescent situation shown in  FIG. 48 . 
     As best shown in  FIG. 49 , the nozzle arrangement also incorporates a test mechanism that can be used both post-manufacture and periodically after the printhead is installed. The test mechanism includes a pair of contacts  8020  that are connected to test circuitry (not shown). A bridging contact  8019  is provided on a finger  8043  that extends from the lever arm  8018 . Because the bridging contact  8019  is on the opposite side of the passive beams  806 , actuation of the nozzle causes the priding contact to move upwardly, into contact with the contacts  8020 . Test circuitry can be used to confirm that actuation causes this closing of the circuit formed by the contacts  8019  and  8020 . If the circuit closed appropriately, it can generally be assumed that the nozzle is operative. 
     Flat Panel Display Device with Integrated Printer 
     A preferred embodiment of the invention is shown in  FIGS. 8 to 25 . Referring particularly to  FIGS. 8 to 15 , a flat panel display unit  141  includes a flat panel display  142  that is supported on a stand  143 . The present invention primarily applies to flat panel displays where a viewable size of the flat panel display exceeds 40 cm measured along a diagonal of the flat panel display. The stand  143  includes a base portion  144 , which supports an arm  145  to which a housing  146  for the display  142  is hingedly connected. Various control buttons  148  are provided on the display unit  141 , for controlling display functions such as contrast, brightness, color temperature and the like. 
     The display unit  141  incorporates a page-width printer (described below) that accepts, in the preferred embodiments shown in  FIGS. 8 to 32 , single sheets of standard A4 or US Letter paper  149 . A curved paper guide  150  causes paper exiting the printer to be directed away from the base  144  of the display unit  141 , as best shown in  FIGS. 9 and 12 . 
     The sub-components that comprise the display unit  141  are shown in exploded view in  FIG. 16 . A mounting plate  151  is hingedly mounted to the arm  145  and attached to a rear cover molding  152  formed from a plastics material. The cover molding is perforated to allow convective air currents to cool the electronic circuitry inside the display unit  141 . 
     A metallic radio frequency interference and electromagnetic interference (RFI/EMI) shield  153  fits inside the concave side of the rear cover molding  152 . The shield  153  screens the various circuitry elements from external radiation, whilst reducing any radiation generated by the circuitry being transmitted from the display unit  141 . The shield  153  takes the form of a cage with cooling holes that allow ventilation of the circuitry. An additional shield  154  covers the printhead (described below in relation to  FIG. 23 ). 
     The various electronic, mechanical and electromechanical components that comprise the printer are mounted on interconnected printed circuit boards (PCBs)  155 , as best shown in  FIGS. 19 to 21 . The PCBs  155  include a printhead PCB  156 , an analog converter PCB  157 , a backlight inverter PCB  158 , and a power supply unit (PSU)  159 . The PSU  159  supplies power at appropriate voltage and current to the various other PCBs via wiring  160 . 
     Turning to  FIG. 22 , the printhead PCB forms part of a print engine assembly  161 . The print engine assembly  161  also includes paper feed rollers  162 , a platen  163  for supporting paper as it is fed past the printhead, an air pump  164  for supplying pressurized air to the printhead, a flexible connector  147  for supplying data from the print engine chips on the print engine PCB to the printhead, an ink delivery bus  165 , and a print engine controller (SoPEC) chip  166 . The feed rollers  162  are driven by a paper drive motor  197  and drive assembly  198 . 
     As shown in  FIG. 23  (in which the platen and feed rollers are removed for clarity), the print engine assembly  161  also includes support metalwork  167  for mounting the various components, copper busbars  168  for supplying power from the power leads  169  to the printheads, and flexible paper guide fingers  170 . Ink channel moldings  171  route ink from the ink delivery bus  165 , which also includes electrical contacts  173  that enable communication between an ink cartridge (described below) and the print engine assembly. It will be noted that the present embodiment includes two printhead segments  174  and  175  of equal length that together form a pagewidth printhead. As described earlier in this document, 
     Referring back to  FIG. 16 , a metal paper chute  176  is provided to guide paper behind the display and down to the printhead. A metal chassis  177  is provided to support the display  142 , which is surrounded and protected by a plastic front bezel molding  178 . A menu PCB  179  holds the menu buttons  148  and associated status LEDs. 
     As best shown in  FIG. 10 , the display unit  141  is provided with power via a mains cord  180  and associated mains plug  181 . The mains plug  181  is inserted into mains socket  182 , which is shown in  FIG. 17  with the mains plug  181  removed. The mains socket  182  is hard-wired into the PSU  159 . 
     A video input cable  183  and associated video plug  184  supply video data from a computer. The video plug  184  is inserted into a video socket  185 , which is shown in  FIG. 17  with the video plug  184  removed for clarity. 
     A data connection in the form of a USB 2 link is provided by way of a data cable  186  and associated data plug  187 . The plug  187  is inserted into a USB 2 compliant data socket  188 , which is shown in  FIG. 17  with the data plug  187  removed for clarity. 
     As shown in  FIG. 21  an ink cartridge  189  containing the various inks required for operation of the printer releasably engages the ink delivery bus  165  via an aperture  190  ( FIG. 16 ) formed in the rear molding  152 . The cartridge is preferably held in position by an interference fit, although a positive retaining mechanism such as a clip can be supplied in alternative embodiments. As best shown in  FIG. 21 , the ink delivery bus  165  includes a plurality of fluid ports  191  that engage with corresponding fluid outputs (not shown) formed in the cartridge. In the embodiment shown, each fluid port  191  includes a hollow needle  192  that penetrates a seal (not shown) in the corresponding fluid output. The seal can be an annular resilient seal with a frangible membrane, or simply a frangible membrane that self-seals around the needle  192  as the cartridge  189  is inserted into an operative position. 
     The cartridge  189  contains the inks necessary for its use with the printer. The various possible combinations of colored inks (such as CMY), black ink, infrared ink and a fixative are described elsewhere in this document. The cartridge  189  also includes a QA (“Question-Answer”) chip that is configured to store information accessible by the SoPEC chip  166 , such as ink levels remaining (preferably on a per-ink basis), types of ink contained in the cartridge, security data for ensuring the cartridge is compliant with the printer&#39;s needs and any other data that might be useful for the operation of the printer based on the particular cartridge inserted. The QA chip is electrically connected to a set of contacts (not shown) that operatively engage the electrical contacts  173  on an edge of the ink delivery bus  165 . The electrical contacts allow information to be read from the QA chip in the cartridge  189  as required. This can be when the cartridge is first inserted, and possibly periodically thereafter. In the preferred embodiment, the SoPEC chip  166  can also write back to the cartridge. Typically, this will involve determining the amount of ink used and then updating the QA chip in the cartridge. 
     A number of other elements of the display unit  141  not shown in other Figures are shown in  FIG. 44 . It will be noted that the flat panel display  142  is preferably a Thin Film Transistor (TFT) Liquid Crystal Display (LCD). However, it will be understood that the particular technology employed in the flat panel display  142  is not critical to the invention. The flat panel display  142  can therefore be of any other type, including those using Organic Light Emitting Diode (OLED), Field Emission Display (FED) and Plasma Display Panel (PDP) technologies. 
     As shown in  FIG. 44  the display unit includes row drivers  193  and column drivers  194  that are provided with input signals by an image processor  195  located on the analog converter PCB  157 . The image processor receives display data from a personal computer (not shown) via the video socket  185 . The fluorescent backlight inverter PCB  158  drives a fluorescent backlight  196 . 
     The USB input  188  ( FIG. 17 ) provides data in accordance with the USB 2 protocol to the SoPEC chip  166 . The image processor  195  can also provide data to the SoPEC chip  166 , as described in detail below. 
     Operation of the display unit will now be described with reference to  FIG. 44 . Display data is received from a personal computer, or other suitable video data source, via the video input socket  185 . The display data is provided to the image processor  195 , which processes and converts it into a format suitable for supply to the row drivers  193  and column drivers  194 . These drive the various TFTs required to display the image on the flat panel display  142 . The fluorescent backlight  196  provides illumination from behind the TFTs, thereby enhancing visibility of images displayed. Various display settings, such as contrast, brightness and resolution, can be altered by a user via the controls  148 . 
     The USB input socket  188  accepts USB formatted data from a connected personal computer, such as personal computer  102  in  FIG. 1 . It will be appreciated that this data can come from any other suitable source, such as a network connection or any other data communication link. 
     Upon receipt, the data is forwarded via an internal USB link to the printhead PCB  156  and the SoPEC chip  166 . The data is decompressed and formatted in accordance with the steps shown in  FIG. 1 , using the hardware  232  described in relation to  FIG. 2 . The formatted data is forwarded from the SoPEC chip  166  to the Memjet printheads  174  and  175 . The data is then printed onto the paper  149  as it is driven past the printheads. 
     In the preferred embodiment, the print button  200  ( FIGS. 8 and 9 ) can be used to generate a printout of the presently displayed image. This enables a printout of the screen to be taken without the need to use a mouse, keyboard or other control device associated with the personal computer  102 . 
     The invention has a number of advantages over the prior art. The combination of a printer and flat panel display saves a considerable amount of room compared to a separate display and printer combination. The printed matter, in the preferred embodiment, is ejected right in front of the user, unlike the case with prior art printers which are, for the most part, too bulky to be placed directly in front of the user. 
     In the particularly preferred embodiment described, the pagewidth nature of the printer and its relatively compact dimensions compared with inkjet and laser printers respectively mean that high quality printing can be provided without substantially increasing the size of the flat panel display casing. Given that a major advantage of flat panel displays is their compactness, this can be considered a major feature of the preferred embodiment. With the use of a pagewidth printhead, there is less vibration than with a reciprocating inkjet printhead, resulting in a more stable image for a user viewing the display whilst printing. 
     An alternative embodiment of the invention is shown in  FIG. 26 , in which like numerals indicate features corresponding to those described in relation to the embodiment of  FIGS. 8 to 25 . The embodiment of  FIG. 26  is a duplex printer, which includes a pair printheads  304  and  305 . The printheads are preferably of the same construction as the single printhead, each comprising two printhead segments. In the preferred embodiment, each of the printheads  304  and  305  has its own associated SoPEC device. 
     In operation, the embodiment of  FIG. 26  prints onto both sides of the paper  149  as it is fed between the printheads  304  and  305 . 
     A further embodiment is shown in  FIGS. 27 and 28 , in which like numerals indicate features corresponding to those described in relation to the embodiment of  FIGS. 8 to 25 . The embodiment includes a multi-sheet feeder  312  that enables a single sheet at a time to be taken from a stack of paper and fed past the printhead. The feeder  312  is best shown in  FIG. 28 , and includes a paper stop  205  that holds a stack of paper  203  in position. The preferred capacity of the stack  203  is about 50 sheets, although other capacities can be used. A flexible shim  206  extends across the top of the paper stop  205 , terminating in an edge adjacent and below a pickup roller  204 . The pickup roller  204  is generally circular in cross-section, but incorporates a flat portion  313 . 
     In use, the paper stack  203  is loaded such that it rest on the flexible shim  206 , which is in turn supported by the paper stop  205 . The pickup roller  204  is positioned rotationally such that the flat portion  313  ( FIG. 28 ) is aligned with the nearest piece of paper in the stack. The pickup roller  204  is then rotated clockwise (relative to  FIG. 28 ), until the rounded portion engages the piece of paper. As this happens, friction between the paper and the roller increases, causing a downward force on the paper. The flexible shim  206  causes the sheet of paper to be separated from the stack  203  and driven downwards towards the feed rollers  162 . As the paper engages the feed rollers, the flat spot rotates back into the position shown in  FIG. 28 , which reduces the friction between the pickup roller and the paper, thereby enabling the feed rollers to push the paper past the printhead. 
     It will be appreciated that any other known paper feeding mechanisms can be employed for taking a single sheet from a stack and feeding it for printing. It will also be appreciated that a duplex printhead arrangement such as that shown in  FIG. 26  can also be employed with a multi-sheet feed mechanism. 
     Another embodiment is shown in  FIG. 29 , in which the sockets  182 ,  185  and  188  are positioned in the base portion  144  of the display unit. This enables a neater arrangement of cables, since there is no need to route them all the way up to the rear molding  152 . Rather, internal wiring takes the power and data from the sockets to the relevant components via the interior of the arms  145 . 
       FIG. 30  shows another embodiment, in which the base portion  144  acts as a data hub. Circuitry (not shown) in the base portion  144  allows the USB connection enabled by socket  188  to send and receive data to and from other devices via data hub connectors  207 . This enables anything from network to peripheral devices to be connected via the base portion  144 , rather than needing to access ports or sockets on the personal computer to which the display unit is connected. This can be advantageous given that ports and sockets on personal computers are often positioned in relatively difficult to access places. Often, the computer device itself is positioned out of the way, such as underneath a desk, which can contribute to this inconvenience of making data connections in the prior art. 
     Yet another embodiment, shown in  FIG. 31 , the ink bus  165  is positioned such that the ink cartridge  189  is positioned on the mounting plate  151 . 
       FIG. 32  shows another embodiment of the invention, in which the ink cartridge  189  is positioned in the base portion  144  of the display unit. In this case, the arms  145  also include ink conduits for supplying ink from the cartridge  189  to the printer. In some cases, it may be necessary to provide some form of pump or other pressurization arrangement to push the ink upwards through the conduits in the arms  145 . 
     One Touch Print Button 
     A desktop printer attached to a personal computer (PC) may usefully incorporate an “Print” button which when pressed causes the active Windows application on the PC to print its entire active document to the printer, without an intervening print dialog. 
     As a variation on this theme, when the printer is embedded in a flat-panel display (FPD), then the Print button may be incorporated in the display. 
     By active application we mean the application whose window is top-most, and with which the user it typically currently interacting. By active document we mean the document displayed in the active application&#39;s top-most window. 
     When the Print button is incorporated in a printer, it is important that the button initiates printing to that printer. When the Print button is incorporated in a display, it is reasonable for it to initiate printing to the default printer, which may or may not be configured to be the in-panel printer. 
     Windows Printing Background 
     There is no single standard way under Microsoft Windows to programmatically instruct the active application to print its active document to the default or to a designated printer. However, there are several mechanisms which may be exploited, covering most application types. Although not explored here, comparable mechanisms exists under other operating systems and windowing systems, including Apple MacOS, Unix, X Windows, Linux etc. It should be appreciated by those skilled in the art that the invention is not limited to use with any particular hardware, operating system or software combination. 
     Printing User Interface 
     Most Microsoft Windows applications, as a matter of convention, provide a fairly standard printing user interface. This consists of: (a) a Print option on the File menu, usually accessible via the two keyboard sequences ALT, F, P and CTRL+P, which displays a print dialog to print the current document; and (b) a Print tool on the toolbar (shown as a printer icon) which prints the current document to the default printer without displaying the print dialog. Dialog-less direct printing has no standard keyboard shortcut. 
     If the active application is receptive to a keyboard sequence in this way, then a client application can instruct it to print by queuing the appropriate keyboard events (using the keybd_event or SendInput SDK functions) or by queuing the appropriate keyboard messages (using the AttachThreadInput, GetFocus, and PostMessage SDK functions). 
     Direct printing can be simulated by appending a carriage-return to the keyboard sequence, causing the print dialog to be completed without further user input. 
     Automation 
     Some Windows applications, including Microsoft Office applications such as Word and Excel, expose an Automation interface (formerly known as OLE Automation), which allows them to be controlled by a separate application. For example, Word (like many other Microsoft applications) exposes a PrintOut method which can be invoked on the active document to print the document directly. A client application can discover an open Word document and print it in this way. The application can designate a particular printer by assigning the name of the printer to Word&#39;s ActivePrinter property prior to invoking the PrintOut method. Automation servers such as Office applications register running instances of themselves in the Running Object Table (ROT). Multi-instance applications (such as Excel and some versions of Word) are only able to create a single application entry in the ROT. However, multi-instance applications typically also register each of their open documents separately in the ROT, allowing the client application to find the application instance corresponding to a particular document via the document&#39;s entry in the ROT. 
     The client application can iterate through the ROT, attach to each server application of interest in turn, and identify whether the application is associated with the foreground window. If the server application is associated with the foreground window (as identified by the GetForegroundWindow SDK function), then the client application can invoke the application&#39;s PrintOut method (or equivalent) to print the active document. 
     In the case of a single-instance application (such as PowerPoint), the client application attaches to the server application directly via the ROT entry. In the case of a multi-instance application (such as Excel), the client application attaches to the server application via a document entry in the ROT. 
     The Windows SDK provides standard functions for obtaining a pointer to the ROT and iterating through it. Application and document entries in the ROT are easily recognised since each entry is associated with a class-specific programmatic identifier. For example, a Word application has the programmatic identifier “Word.Application.x” (where x indicates the application version), and a Word document has the identifier “Word.Document.y” (where y indicates the document version). An application entry in the ROT conventionally includes the application&#39;s class identifier in its name, from which the corresponding programmatic identifier can be obtained via the Windows registry. A document entry in the ROT allows its programmatic identifier to be discovered via the class identifier associated with the document&#39;s persistence interface. 
     Because there are several ways to programmatically instruct the current application to print its active document to the default or to a designated printer, and because no single way is optimal for all applications, support for a “Print” button is best provided (in this embodiment) by invoking the mechanism most appropriate to the current application according to the current application&#39;s type. 
     In its simplest form, this consists of first trying to find the active application in the ROT, specifying the target printer by setting the active application&#39;s ActivePrinter property, and invoking the active application&#39;s PrintOut method. If the active application is not found in the ROT, then the fallback consists of queuing the standard print-invocation keyboard sequence (i.e. Control key down, P key down, P key up, Control key up, CR key down, CR key up). 
     In a more sophisticated implementation, a table of applications is created which lists the mechanism most appropriate to each application type, i.e. Automation versus keyboard sequence, and exact application properties and methods to use, or exact keyboard sequence to send. Automation server applications are identified by their programmatic identifiers, while conventional applications are identified by their names. For example, Word is identified by its programmatic identifier “Word.Application.x”, while Notepad is identified by its name “Notepad”. It is straightforward to identify the foreground window (via the GetForegroundWindow SDK function) and extract the name of the corresponding active application from the window&#39;s title (via the GetWindowText SDK function). 
     The “Print” button can be a physical momentary switch or it can be simulated via another interface on the printer (or FPD) such as a touch-sensitive display. In any case, when the user presses the print button, an event is relayed to a background application on the PC which invokes the corresponding printing function as described above. The background application may already be executing, i.e. awaiting events, or it may be activated by the user&#39;s act of pressing the “Print” button. The button event can be relayed by the control software in the printer, via the printer&#39;s communications interface and its printer driver, and thence to the background application. Alternatively cacan be relayed via its own communications interface and driver, in which case the driver and the background application may be one and the same. For example, the print button can be provided in the form of a separate Universal Serial Bus (USB) device on the USB bus, but may share the physical USB connection between the printer (or FPD) and the PC. In the preferred embodiment, the background application is capable of handling the “Print” buttons of multiple devices. To allow it to distinguish multiple buttons, each button event in this embodiment uniquely identifies its originating button. An event may include a unique identifier associated with the printer in which the button is embedded, or a unique identifier associated with the button itself, retrieved from non-volatile storage attached to the button. 
     In cases where the target printer can be selected by setting the active server application&#39;s ActivePrinter property, the background application must know which printer name to specify. Since it may be difficult for the background application to know the name of the printer associated with a particular “Print” button it is servicing, it is useful to allow the user to associate a printer with each button, indexed by the button&#39;s unique identifier. If a button is pressed which has no associated printer, then the background application can determine how many printers are configured on the PC. If there is only one printer, then the application has no need to specify a printer since the one printer must be the default printer. If there are several printers, then the application can prompt the user to select one, and can then record the association between the selected printer and the button. It is straightforward for the background application to enumerate the available printers using the EnumPrinters SDK function. 
     Various exemplary, non-limiting aspects of the invention are foreshadowed in the following numbered paragraphs: