Abstract: Print quality is maintained by determining print conditions based on varying threshold values over the printhead lifetime before the print run. In particular, print conditions are determined through periodic quality adjustment cycles based on detected long-term and short-term temporal drift of print thresholds. A detector is provided to detect the presence or absence of ink being ejected from an inkjet printer. A sequence of eject and detect cycles over varying control conditions is performed to determine the minimum condition required to eject ink from the printer.

Abstract: An ink jet printer including an ink jet printhead and a printhead temperature sensing device including a fusible link circuit with a preview feature and a method for programming or calibrating therefore. The ink jet printhead includes a fusible link circuit including a fusible link, with a threshold above which the fusible link will be forced to an open condition with the application of a threshold condition applied thereto and a circuit, coupled to the fusible link, including an input and an output, generating an output signal on the output in response to a signal being applied to the input, wherein the output signal provides an output state which simulates the open condition of the fusible link as a preview feature. The fusible link circuit includes the preview feature so that the output of the temperature sensing device which must be calibrated, programmed, or have its output set to a predetermined value, can be simulated or previewed to determine whether the correct output has been achieved.

Abstract: A fusible link circuit including a preview feature and a method for programming or calibrating therefore. The fusible link circuit includes a fusible link, including a threshold above which the fusible link will be forced to an open condition with the application of a threshold condition applied thereto and a circuit, coupled to the fusible link, including an input and an output, generating an output signal on the output in response to a signal being applied to the input, wherein the output signal provides an output state which simulates the open condition of the fusible link as a preview feature. The fusible link circuit includes the preview feature so that the output of any circuit, which must be calibrated, programmed, or have its output set to a predetermined value, can be simulated or previewed to determine whether the correct output is obtainable without destroying the fusible links.

Abstract: A liquid recording apparatus ejects droplets of liquid onto a recording medium. The apparatus has multiple liquid emitters whose emissions are activated by multiple power pulses. The power pulses are controlled to maximize the number of emitters which can be simultaneously energized while keeping the instantaneous power usage within prescribed boundaries. The multiple emitters are organized into banks of emitters whose numbers are small enough that all emitters within a bank can receive a correct level of power simultaneously without exceeding capacity of a shared power source. A circuit interleaves the power pulses to the emitters so that no bank of emitters are receiving power at the same instant of time.

Abstract: An improved temperature compensation method is disclosed in which a temperature sensing thermistor is formed on a substrate whose temperature is to be series of fractional thermistors which are selectively shorted out during a manufacturing process to provide a compensation for manufacturing variabilities of the temperature coefficient of resistance of the thermistor.

Abstract: An ink jet printing system includes an ink jet printhead which has an n-bit code representing a unique characteristic of the printhead formed on a substrate forming a part of the printhead. An n-bit data code is sent from a remote source to the printhead. If the data code matches the code on the printhead, printing operation is initiated. If the code is not matched, the print operation is inhibited.

Abstract: A method for electrical tailoring of thermal ink jet heater elements. The resistance of ink-jet heater elements formed of polysilicon is changed by applying energy through the resistor element of varying amounts at varying pulse widths. The application of pulsed current for up to 1 second total pulse width at voltages of up to 50 volts decreases the resistance by as much as thirty percent or more of the as fabricated values.

Abstract: Individual printheads are joined together in a manner to provide improved alignment and registration. The multiple printhead assembly is then installed and removed from the printer as a single unit. According to a preferred method of forming the assembly, individual printheads are temporarily mounted on a holddown plate. The location and position of the printheads is monitored and a fast-cure adhesive used to monolithically join the individual printheads together as a unitary assembly. Once the adhesive is cured, the temporary securing of the individual printheads is removed and the entire assembly removed as a single unit from the holddown plate.

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: 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: An electrostatic discharge protection device for a connector associated with an integrated circuit chip, particularly one associated with a thermal ink-jet printhead. AMOS field effect device extends along at least one edge of the connector on the chip. A bipolar transistor, parasitic to the field effect device, conducts current from the connector to ground in response to a voltage between the connector and ground in excess of a predetermined threshold. A zone of a predetermined electrical resistance is operatively disposed between the bipolar transistor and ground. The zone may substantially encircle the bonding pad of the connector to evenly distribute local incidences of high voltage. The invention enables integrated circuits to pass ESD requirements of office products, which is 15 kV by Human Body Model testing.

Abstract: A method and apparatus for maintaining a print quality of an ink jet apparatus comprises selecting one of a plurality of different pulse signals to apply to at least one heating element. The heating element is energized with the selected pulse signal. An actual voltage drop is then measured across the heating element. The actual voltage drop is subsequently compared with a desired voltage drop. Then, a new pulse signal is selected to energize the heating element based on the results of the comparison. The repetitive process continues until the actual voltage drop is substantially equal to the desired voltage drop. In another embodiment, a bubble sensor is used to determine whether a bubble has been formed over the heating element.

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: 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: 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: An electrostatic discharge protection device for a connector associated with an integrated circuit chip, particularly one associated with a thermal ink-jet printhead. A MOS field effect device extends along at least one edge of the connector on the chip. A bipolar transistor, parasitic to the field effect device, conducts current from the connector to ground in response to a voltage between the connector and ground in excess of a predetermined threshold. A zone of a predetermined electrical resistance is operatively disposed between the bipolar transistor and ground. The zone may substantially encircle the bonding pad of the connector to evenly distribute local incidences of high voltage. The invention enables integrated circuits to pass ESD requirements of office products, which is 15 kV by Human Body Model testing.

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.