Abstract: The invention discloses a system and method for sensing changes in the weight of an ink reservoir which supplies ink to a printhead which ejects ink onto a recording medium during a printer operational mode. The ink reservoir, whether located separately from the printhead, as in a plotter or pagewidth printer embodiment, or mechanically attached to the printhead and moved in a scanning printhead architecture, has its weight supported by a structure. A strain gage or other weight sensor is affixed to the supporting structure and incorporated in a circuit which produces an output signal representative of resistive changes in the weight sensor. Since a resistive change in the weight sensor is caused by a decrease in the supply of ink in the reservoir during continued printer operation, the output signal is proportional to the ink level.

Abstract: An ink jet printer has a temperature sensor as a permanent part thereof to measure the temperature of printheads which are an integral part of a replaceable printhead cartridge assembly. The temperature sensor is a part of the maintenance station and senses the temperature of the printheads each time the printhead enters the maintenance station. In the preferred embodiment, the temperature sensor is spring-loaded and is located at a printhead spitting location between fixed wiper blades and the capping location in the maintenance station, so that temperature is sensed each time the printhead enters and leaves the maintenance station to eject nozzle cleaning droplets onto a collection surface at the spitting location to clean the printhead nozzle face by the wiper blades, or to cap the printhead nozzles. To facilitate good thermal contact, a recess is provided in the heat sink upon which the printhead resides for entry by the spring-loaded temperature sensor.

Abstract: A capacitor is created in an ink tank supplying ink to an ink jet printhead by placing parallel capacitive plates on sides of the tank with the ink therebetween acting as the capacitor dielectric. An electrical AC potential is applied across the capacitor. Changes in current flow through the plates are detected in a phase sensitive bridge circuit and digital signals are generated and sent to a processor for conversion into low ink level signals. The output signal is also used to identify a particular type of ink by either comparing points on a characteristic curve of the ink volume verses capacitance or, in a second embodiment, by periodically sweeping an applied oscillator voltage over a selected frequency range and comparing measured electrical resonance parameters for the ink tank capacitor with stored information about resonance parameters for different types of ink.

Abstract: An ink-jet printer includes a printhead disposed on a reciprocating carriage. The printhead includes two sets of ejectors spaced by a predetermined pitch, in collinear linear arrays. The two sets of ejectors are offset by a partial pitch to enable interleaving of print swaths by the two sets of ejectors, in order to print at a higher resolution than the predetermined pitch would allow.

Abstract: An ink jet printer includes a printhead having a plurality of segments each having ink ejecting nozzles, each segment supplied with ink of a different characteristic. Means are provided for moving the printhead in a direction transverse to the advancing movement of a recording medium. Means are further provided for moving the printhead between two or more positions along the recording medium advance direction. Thus, the printhead can print a swath of ink of a first characteristic from one segment and then be moved to print a second swath from a second segment with ink of a second characteristic. In one embodiment, a printhead has two segments, one printing in black, and the other in color. A shift mechanism is enabled to move the printhead between a black print position and a color print position. The invention contemplates alternate color printing swaths at alternate printing positions along the same printing swath, or a combination thereof.

Abstract: An ink jet printer has a temperature sensor as a permanent part thereof. The temperature sensor is mounted on the translatable carriage of the printer. A replaceable printhead cartridge having a printhead bonded to a heat sink is installed on the translatable carriage. Once the printhead cartridge is installed on the translatable carriage, the temperature sensor is placed into intimate contact with printhead'heat sink, so that the temperature sensor moves with the printhead and provides continual temperature measurement.

Abstract: A power control system in a thermal ink-jet printer facilitates practically instantaneous voltage changes to a heating element. A first set of selectably-actuable voltage lines is operatively connected in parallel to a first terminal of the heating element, each line having associated therewith a predetermined voltage output. A second set of selectably-actuable voltage lines is operatively connected in parallel to a second terminal of the heating element, each line having associated therewith a predetermined voltage output. One of the first set of selectably-actuable voltage lines and one of the second set of selectably-actuable voltage lines are activated as required.

Abstract: A thermal ink-jet printhead adapted to emit ink onto a print sheet is automatically adjusted. The printhead is caused to emit ink onto a sheet in a manner consistent with an image of a first density, and then substantially immediately caused to emit ink in the form of a first test pattern on the sheet. The density of the first test pattern on the sheet is measured. The printhead is caused to emit ink onto the sheet in a manner consistent with an image of a second density, and then substantially immediately caused to emit ink in the form of a second test pattern on the sheet. The density of the second test pattern on the sheet is measured. The densities of the first test pattern and the second test pattern are correlated with a function relating a characteristic of an image printed with the printhead to a temperature of the printhead.

Abstract: A control system for a printer having at least one heating element for producing spots applies one of a plurality of voltage levels to at least one heating element disposed on a printhead. A voltage supply supplies a voltage to a first one of a plurality of switches connected in series with a last one of the switches being connected to the at least one heating element. At least one of the switches defines a first path and a second path having different voltage drops. A controller coupled to the plurality of switches selectively actuates the switches to apply one of a plurality of predetermined voltages to the at least one heating element.

Abstract: Data relating to the performance of an individual ink-jet printhead is stored in an electrically-readable form on a silicon substrate forming an essential part of the printhead. A template of electrically-detectable structure is created on the substrate at manufacture, and then portions of the structure are removed in accordance with the data desired to be stored. In one embodiment, the digital performance data may be encoded and also read out in serial form using a shift register on the chip.

Abstract: An apparatus and method compensates for a voltage drop of electrical pulse signals selectively applied to a plurality of heater elements on a printhead of an ink jet printing device. A number of heater elements to be pulsed at a given time is determined and a time duration of each of the pulse signals is selected based on information including the determined number of heater elements to be pulsed. In another aspect, the position on the printhead of the heater elements to be pulsed is determined and the time duration of the pulse signals is selected further based on the determined position. By varying the time duration of the pulse signals applied to the heater elements, a voltage drop across the heater elements due to the number of heater elements simultaneously pulsed and/or the position of the heater elements on the printhead is compensated for, maintaining reliable jetting performance while minimizing the voltage by which operating printing voltage needs to exceed the threshold printing voltage.

Abstract: A thermal ink jet printhead is controlled to minimize missing droplets at elevated operating temperatures by varying the voltage and pulse width applied to the heater element that causes droplets to be formed and ejected. Increasing the applied voltage reduces the size of the formed droplets. At increased operating temperatures, smaller droplets minimize the introduction of air into the nozzles of the printhead upon ejection. Minimizing the introduction of air eliminates printhead misfirings and causes more consistent jetting of the ink droplets.

Abstract: A thermal ink-jet printhead comprises a substrate having a plurality of heating elements defined thereon. A thermistor, disposed on the substrate, includes a conductor loop which does not encompass the heating elements on the substrate. The configuration of the thermistor significantly reduces both electromagnetic and capacitance interference caused by the heating elements.

Abstract: A printhead with a printhead die, an ink manifold and heat sink substrate has a continuous sealing surface surrounding the printhead die which is formed by the ink manifold, heat sink substrate and filler material disposed therebetween. The filler material acts as caulking to eliminate gaps around the printhead die, particularly between the ink manifold and heat sink substrate, and to provide a smooth surface for abutment with a capping member. A fluid-tight seal is obtained between the capping member and the continuous sealing surface on the printhead, thus preventing the drying out of ink in the nozzles through evaporation of volatile ink components. In some priming nozzle configurations, the leaktight seal also facilitates priming of the printhead.

Abstract: A thermal ink jet nozzle array comprises a support bar having two major opposing faces parallel to each other and spaced apart by a known thickness and a linear series of modular multi-nozzle printhead units on each support bar face. The series of modular printhead units are spaced apart from each other by equal and known distances, and the series on each support bar face are in a staggered relationship to each other, so that each end nozzle of each intermediate printhead unit is spaced laterally from the respective end nozzle of the nearest printhead unit in the other series by a distance equal to the inter-nozzle spacing of each printhead unit. The row of nozzles of each printhead unit is accurately and releasably positioned on the support bar by mechanical contact of the printhead unit itself against either external jigging or patterned features permanently fabricated on the support bar faces.

Abstract: A system controls an ink jet printing apparatus for propelling ink jet droplets on demand from a printhead having a plurality of drop ejectors. In the printhead, each ejector includes a heating element actuable in response to electrical input signals, each input signal having an amplitude and a time duration, selectably applied to the heating element to produce a temporary vapor bubble and cause a quantity of ink to be emitted for the creation of a mark on a copy sheet. The temperature of ink in the printhead is sensed, and a combination of power level and time duration of the electrical input signal for the heating element to result in a desired size of the mark of the copy sheet is selected, by entering the sensed temperature of the ink into a predetermined function relating the energy of the electrical input signal to the corresponding resulting size of the mark on the copy sheet.

Abstract: A thermal ink jet printer is disclosed which has a printhead that is maintained at a substantially constant operating temperature during printing. Printing on demand is accomplished by the ejection of ink droplets from the printhead nozzles in response to energy pulses selectively applied to heating elements located in ink channels upstream from the nozzles which pulses vaporize the ink to form temporary bubbles. To prevent printhead temperature fluctuations during printing, especially in translatable carriage printers, the heating elements not being used to eject droplets are selectively energized with energy pulses having insufficient magnitude to vaporize the ink.

Abstract: An ink jet printhead is fabricated with a resistive temperature sensor formed adjacent to the heater resistors and, in a preferred embodiment, of the same material. Temperature sensing variations between a plurality of printheads used in the same printer is achieved by trimming the termistors to the desired resistance value while holding the printhead at the nominal set temperature. In one embodiment, the heater resistor and thermistor are formed within the same polysilicon layer, and the resistor trimmed therein. In a second embodiment, a thick or thin film resistor is formed of bonded in series with the polysilicon thermistor with the trimming being accomplished at the thick, or thin film resistor.

Abstract: Modular partial bars include a substrate bar having a length and a plurality of printhead subunits attached to only one side of the substrate bar, each printhead subunit being spaced from an adjacent printhead subunit. These modular partial bars are used as building blocks to form full width staggered array printheads. When the printhead subunits are arranged on each substrate bar so that two substrate bars are capable of forming a full width staggered array printhead, each modular partial bar is referred to as a modular half bar. One modular half bar can be stacked on another modular half bar any number of ways. For example, two half bars can be stacked with their printhead subunit containing sides facing the same direction, away from one another or towards one another.

Abstract: A method and apparatus actuates a line of printing elements to form characters on a recording medium contained on a curved surface of a platen. The printing elements are sequentially actuated, starting with nozzles located furthest from the platen and proceeding towards printing elements located closest to the platen until the actuation of all element has been performed. The line of printing elements can form a printhead which includes a plurality of nozzles arranged in at least one line having opposing ends, this line being substantially perpendicular to a longitudinal axis of the curved platen. Preferably, the line of nozzles is arranged with its center located closest to the platen and the nozzles are actuated starting at the ends of the line of nozzles.