A typical inkjet printer produces an image by ejecting small drops of ink from the printhead containing an array of spaced apart nozzles, and the ink drops land on a receiver medium at selected pixel locations to form round ink dots. To print an image, an ink jet printer deposits droplets of ink onto a print medium in a desired pattern. The ink is ejected from the nozzles of one or more printheads of the printer. It may be forced out of the nozzles by the activation of a piezoelectric or thermal element mounted in a firing chamber behind each nozzle. In the inkjet printer, information data for printing the images is transferred to the print cartridge through a portion of the print cartridge, wherein the print cartridge contacts a cartridge shaft along which the print cartridge is moved. An inkjet printer is typically constructed such that, while a carriage having an ink-jet head mounted thereon is moved in the main scan direction perpendicular to the direction of conveyance of recording media, energy for causing ink to eject is applied to each of the ink chambers in accordance with image data. An ink jet printer typically includes a reciprocating printhead carrier that transports one or more ink jet printheads across the print media sheet along a bi-directional scanning path defining a print zone of the printer. A paper feeding mechanism is used to incrementally advance the print media sheet in a sheet feed direction, also commonly referred to as a sub-scan direction or vertical direction, through the print zone between scans in the main scan direction, or after all data intended to be printed with the print media sheet at a particular stationary position has been completed. An ink jet printer includes a carriage reciprocally moving on a main frame, on which an ink cartridge and a print head are mounted. The carriage is movably mounted on a guide shaft in a perpendicular direction to a feeding direction of the recording piece of paper. The carriage is also connected to a timing belt that is fitted around a drive pulley coupled to a rotary shaft of a pulse motor. The carriage is reciprocated across the width of the printer as paper or other print media is advanced through the printer. Each ink-filled cartridge includes a printhead that is driven to expel droplets of ink though nozzles in the printhead toward the paper in the printer. As the motor rotates, the carriage is moved in a main scanning direction relative to a recording sheet. The inkjet head used on those inkjet printers has a plurality of ink ejection nozzles provided adjacent to each other in one direction, with a discrete ink channel being connected to each of those ink ejection nozzles such that ink is kept supplied to them. In an inkjet printer that uses the separate ink cartridges, a cartridge accommodating portion accommodates the ink cartridges. Each ink cartridge must be accurately located at a predetermined position of the accommodating portion.

Inkjet printers utilize a printhead which contains various electrical and mechanical components for causing ink to be injected onto a print medium to form an image. Inkjet printers frequently make use of an inkjet printhead mounted within a carriage that is moved back and forth across print media, such as paper. An inkjet printer typically includes a printhead having a plurality of independently addressable firing devices. Each firing device includes a firing chamber connected to a common ink source, an ink propulsion device, and an ink expulsion nozzle. The ink propulsion device within the firing chamber provides the impetus for expelling ink droplets through the nozzles. As the printhead is moved across the print media, a control system activates the printhead to deposit or eject ink droplets onto the print media to form images and text. Ink is provided to the printhead by a supply of ink that is either carried by the carriage or mounted to the printing system not to move with the carriage. The printhead includes a semiconductor chip containing ejection devices and a nozzle plate for ejecting ink from the printhead. The chips also contain integrated circuits that are coupled to the ejection devices on the chips. Proper operation of the ejection devices and circuits is impacted by the construction of the chips. The semiconductor chip is preferably made of silicon and contains various passivation layers, conductive metal layers, resistive layers, insulative layers and protective layers deposited on a device side thereof. The inkjet printhead may be incorporated into a carriage type printer, a partial width array type printer, or a pagewidth type printer. The carriage type printer typically has a relatively small printhead containing the ink channels and nozzles. The printhead can be attached to a disposable ink supply cartridge as one piece, and the combined printhead and ink cartridge assembly is attached to a carriage. The pagewidth printer includes a substantially stationary printhead having a length sufficient to print across one dimension of a sheet of recording medium at a time. The recording medium is moved past the page width printhead in a direction substantially perpendicular to the printhead length.

Ink jet printers use different printing heads. The inkjet printhead may be classified into one of a thermal transfer type and a piezoelectric device type according to a method of ejecting the ink onto a sheet of print paper. Among inkjet heads those which employ a piezoelectric element have increasingly come into the limelight in recent years due to its excellency in energy efficiency. Piezoelectric inkjet head generally includes a piezoelectric element, one common ink chamber which receives from an external device and stores ink, a plurality of pressure chambers coupled to the piezoelectric element, and a nozzle plate so connected to the pressure chambers that one nozzle may be connected to each pressure chamber. The nozzles are in communication with the pressure chambers as temporary ink retainers. The pressure chambers are open at their upper portions. The diaphragm made from glass or resin covers the open portions of the pressure chambers. A piezoelectric element or piezoelectric block allocated to each pressure chamber may deform independently of those assigned to other pressure chambers, and thus each nozzle can jet ink independently of other nozzles. Each piezoelectric element is typically comprised of a capacitive load containing a capacitor. A piezoelectric element deformation applies pressure to a reservoir of ink within an ink storing chamber of the printing head, thus causing at least a portion of the reservoir to be discharged from a nozzle in communication with such reservoir. The piezoelectric elements are flexed, thereby causing associated portions of the diaphragm to be flexed too. The capacity of the pressure chambers is reduced so as to emit ink via nozzles. When the voltage is interrupted, the piezoelectric elements and the diaphragm return to their normal state. Thereafter, the pressure chambers suck in ink from ink supplies, thereby preparing for succeeding ink emission. By expansion and restoring (shrinkage) of the piezoelectric elements, the pressure is applied to the ink in the respective ink chambers. The ink chambers communicate with the corresponding ink ejecting holes, respectively. When the pressure is applied, the ink is ejected from the ink chambers to the outside through the ink ejecting holes. The ink ejecting holes are formed on a nozzle plate, which is attached to the actuator. These ink ejecting holes are arranged in the directions of conveyance of recording papers and movement of the head.

In the case of thermal inkjet printers, a print head structure comprises a single or plurality of ink cartridges each having a nozzle plate that includes a plurality of nozzles. Each nozzle is in communication with a corresponding ink ejection chamber formed in the print head cartridge. In thermal transfer type printheads, a heater placed at a convenient location within the nozzle or at the nozzle opening heats ink in selected nozzles and causes a drop to be ejected to the recording medium in those nozzles selected in accordance with image data. A resistive heater is disposed in each ink ejection chamber and is connected to a controller, which selectively supplies sequential electrical pulses to the heaters for actuating the heaters. When the controller supplies the electrical pulses to the heater, the heater heats a portion of the ink adjacent the heater, so that the portion of the ink adjacent the heater vaporizes and forms a vapor bubble. Formation of the vapor bubble pressurizes the ink in the ink ejection chamber, so that an ink drop ejects out the nozzle to produce a mark on a recording medium positioned opposite the nozzle. The bubble-jet type printer ejects ink droplets by means of bubbles generated by a heating element heating liquid ink. The bubble-jet type inkjet printer heats liquid ink by a heat generating device to generate a bubble, and discharges ink using the bubble. In a head of the bubble-jet type inkjet printer, a nozzle plate having a nozzle is disposed on one side of a chamber barrier layer providing an ink chamber, and a heater substrate where a heater is installed is arranged to correspond to the ink chamber and disposed on the other side of the chamber barrier layer. As a voltage is applied across a selected heater, a vapor bubble grows in that particular channel and ink bulges from the channel nozzle. At that stage, the bubble begins to collapse. The ink within the channel retracts and then separates from the bulging ink thereby forming a droplet moving in a direction away from the channel nozzle and towards the recording medium whereupon hitting the recording medium a spot is formed. However, the bubble-jet printers are similar to the thermal printers in that each use heat for ejecting ink. Thus, inkjet printers may be generally divided into piezoelectric and thermal types of printers. For thermal inkjet printers, individual heater resistors are defined in the resistive layers and each heater resistor corresponds to a nozzle hole in the nozzle plate for heating and ejecting ink toward a print media. In thermal transfer type printers, since there are no moving parts, and since a switching resistor exists, reliability of the inkjet printer can be improved.

There are two general types of methods of supplying ink to a printing head used in such an inkjet printing apparatus. The continuous type ink supply system is a system in which continuously ejected ink particles are charged in accordance with electric signals, and only needed ink particles are ejected on paper. In continuous inkjet printing, a continuous stream of droplets is discharged from each nozzle and deflected in an imagewise controlled manner onto respective pixel locations on the surface of the recording member, while some droplets are selectively caught and prevented from reaching the recording member. In continuous inkjet printers, a pressurized ink is formed into continuous inkjet filaments which project from closely spaced ink discharge nozzles in a nozzle plate on a printhead. Filament stimulation sources such as ink heaters or transducers operate as ink droplet generators each time they are activated, by causing filament end-lengths to be broken off at the respective nozzles. The continuous supply type is further categorized into two types. One is a type referred to as an on-carriage type in which ink is supplied by integrally or detachably attaching an ink tank to a printing head that is carried and moved back and forth by a carriage. The other is a tube supply type in which an ink tank that is separate from a printing head carried on a carriage is fixedly installed in a part of a printing apparatus other than the printing head and in which the ink tank is connected to the printing head through a flexible tube to supply ink. Continuous ink jet printers are are widely used for printing information, such as expiry dates, on various types of substrate passing the printer on production lines. Drop-on-demand ink jet printers selectively eject droplets of ink toward a printing media to create an image. Such printers typically include a print head having an array of nozzles, each of which is supplied with ink. Each of the nozzles communicates with a chamber that can be pressurized in response to an electrical impulse to induce the generation of an ink droplet from the outlet of the nozzle. Drop-on-demand Ink jet printing provides ink droplets for impact upon a recording surface using a pressurization actuator (thermal, piezoelectric, etc.). Selective activation of the actuator causes the formation and ejection of a flying ink droplet that crosses the space between the printhead and the print media and strikes the print media. The formation of printed images is achieved by controlling the individual formation of ink droplets, as is required to create the desired image. In drop-on-demand inkjet printing, individual droplets are ejected as needed on to the recording medium to form the desired image. Common methods of controlling the ejection of ink droplets in drop-on-demand printing include piezoelectric transducers and thermal bubble formation using heated actuators.

Color inkjet printers generally incorporate multiple printheads in a scanning carriage which scans left to right and right to left across a medium while the printheads eject droplets of ink. The printhead of an ink jet color printer typically has at least one nozzle array for each color. Each nozzle array comprises a plurality of nozzles which are arranged equidistantly on a line that extends in a direction orthogonal to the main scanning direction. The distance between neighboring nozzles corresponds to the distance between adjacent pixels of the image to be printed, so that the number of pixel lines that can be printed in one scan pass corresponds to the number of nozzles in the array. While a head in which a plurality of nozzles are integrally arranged is moved in a direction perpendicular to a direction (sub-scanning direction) along which a printing medium such as a paper sheet is fed, ink particles ejected from the nozzles of the head are impacted on the printing medium, thereby forming ink dots on the medium to record an image. Color printers typically include a black printhead, a cyan printhead, a magenta printhead, and a yellow printhead aligned in the scanning carriage so that they scan over the same portion of a medium. During a forward scan pass of the printhead, the ink droplets of different colors will be superposed on the recording sheet in the order C-M-Y, and during a return stroke or scan pass of the printhead, the ink droplets will be superposed in reverse order. The printheads are typically housed in one or more print cartridges either containing ink or having ink supplied to them from an external source. The ink is channeled to ink ejection chambers formed on a substrate associated with each printhead. Within each of the ink ejection chambers is an ink ejection element, such as a resistive heater or a piezoelectric element. A nozzle plate resides over each printhead such that each nozzle is aligned over an ink ejection chamber. Each nozzle head has a row of nozzles arranged in the subscanning direction. Thus, when the carriage is moved back and forth across the recording medium in the main scanning direction, each nozzle head prints a swath on the recording medium during each pass of the carriage. When the nozzle heads are aligned in the main scanning direction, the different color components are superimposed one upon the other during each pass, and the desired hue of the image is obtained by subtractive color composition. In order to produce full vibrant colors on a print medium, large volumes of indicia forming material must be deposited in concentrated areas on the medium.