Abstract: A method of operating a printer enables the mass of the ink drops ejected by the printheads in the printer to maintained in an optimal range without measuring the drop mass being ejected by the inkjets in the printheads. After calibration of the printheads, the printheads are operated with electrical signals having different peak-to-peak voltages. The number of inoperable inkjets for each printhead is determined from image data of the ejected ink on the image receiving member and the number of inoperable inkjets for each printhead is compared to a predetermined threshold. The peak-to-peak voltage for the electrical signals used to operate a printhead is adjusted with reference to the number of inoperable inkjets and the predetermined threshold.

Abstract: A method of operating a printer enables the mass of the ink drops ejected by the printheads in the printer to maintained in an optimal range without measuring the drop mass being ejected by the inkjets in the printheads. After calibration of the printheads, the printheads are operated with electrical signals having different peak-to-peak voltages. The number of inoperable inkjets for each printhead is determined from image data of the ejected ink on the image receiving member and the number of inoperable inkjets for each printhead is compared to a predetermined threshold. The peak-to-peak voltage for the electrical signals used to operate a printhead is adjusted with reference to the number of inoperable inkjets and the predetermined threshold.

Abstract: An ink jet printer includes an ink feed apparatus. The ink feed apparatus includes an ink feed channel for conducting discrete substantially solid ink sticks along a feed channel path, a plurality of ink sticks in the ink feed channel, each of the ink sticks comprising an ink stick body having an ink stick sensing feature on an external surface of the ink stick body that is located between a first end and a second end of the ink stick body, and each of the ink stick bodies has substantially the same mass as the other ink stick bodies in the plurality, a detector positioned at a fixed position proximate the ink feed channel and configured to be triggered by an ink stick sensing feature on an ink stick in the ink feed channel as the ink stick moves along the ink feed path past the detector, and a counter configured to accumulate the number of times the detector is triggered.

Abstract: An ink jet printer includes an ink feed apparatus. The ink feed apparatus includes an ink feed channel for conducting discrete substantially solid ink sticks along a feed channel path, a plurality of ink sticks in the ink feed channel, each of the ink sticks comprising an ink stick body having an ink stick sensing feature on an external surface of the ink stick body that is located between a first end and a second end of the ink stick body, and each of the ink stick bodies has substantially the same mass as the other ink stick bodies in the plurality, a detector positioned at a fixed position proximate the ink feed channel and configured to be triggered by an ink stick sensing feature on an ink stick in the ink feed channel as the ink stick moves along the ink feed path past the detector, and a counter configured to accumulate the number of times the detector is triggered.

Abstract: An ink jet printer includes an ink supply system and a printhead with nozzles for ejecting ink drops. The printer determines the average size of the ejected ink drops by comparing the number of ink drops ejected in a predetermined time with the quantity of ink delivered through the printers ink supply system during that time. If the determined average ink drop size does not match predetermined ink drop size criteria, the printer adjusts the activation signals for the ink jet nozzles to alter the ink drop size. A solid ink printer determines the quantity of ink delivered through the ink supply system by counting the number of whole or partial ink sticks that pass a predetermined point in the ink supply system. The counter detects a sensing element formed on an external surface of the ink stick. Exemplary detectors include a mechanical arm, or a thermistor to detect a change in the printer melt plate temperature due to a change in the cross sectional area of an ink stick being melted.

Abstract: An ink jet printer includes an ink supply system and a printhead with nozzles for ejecting ink drops. The printer determines the average size of the ejected ink drops by comparing the number of ink drops ejected in a predetermined time with the quantity of ink delivered through the printers ink supply system during that time. If the determined average ink drop size does not match predetermined ink drop size criteria, the printer adjusts the activation signals for the ink jet nozzles to alter the ink drop size. A solid ink printer determines the quantity of ink delivered through the ink supply system by counting the number of whole or partial ink sticks that pass a predetermined point in the ink supply system. The counter detects a sensing element formed on an external surface of the ink stick. Exemplary detectors include a mechanical arm, or a thermistor to detect a change in the printer melt plate temperature due to a change in the cross sectional area of an ink stick being melted.

Abstract: An ink jet printer includes an ink supply system and a printhead with nozzles for ejecting ink drops. The printer determines the average size of the ejected ink drops by comparing the number of ink drops ejected in a predetermined time with the quantity of ink delivered through the printers ink supply system during that time. If the determined average ink drop size does not match predetermined ink drop size criteria, the printer adjusts the activation signals for the ink jet nozzles to alter the ink drop size. A solid ink printer determines the quantity of ink delivered through the ink supply system by counting the number of whole or partial ink sticks that pass a predetermined point in the ink supply system. The counter detects a sensing element formed on an external surface of the ink stick. Exemplary detectors include a mechanical arm, or a thermistor to detect a change in the printer melt plate temperature due to a change in the cross sectional area of an ink stick being melted.

Abstract: An improved media-width phase-change ink-jet print had (102) maintains a uniform temperature across its width to produce consistent drop mass and uniform print quality. The print head uses a heater (120) including two separately controlled, overlapping heating zones (154). The heating zones produce heat gradients (170, 172) that have maximum outputs toward opposing edges (168a, 168b) of the print head and are controlled in response to thermistors (138s, 168b) positioned at the corresponding edges. The two heating zones together produce a linear heat gradient (180) across the print heat to compensate for uneven head-to-drum spacing (166) and other unsymmetrical thermal loads on the print head. The improved print head also includes baffles (192) that reduce air flow between the head and the attached reservoir (118), and thermal breaks (218) that insulate the section (220) of the head that includes the jets from the thermal gradients at the edges of the print head.

Abstract: A discrete ink level sensing system according to the present invention includes a level sensing probe (130) with at least first and second level sensing pads (178, 180) that is placed in an ink reservoir (28). The level sensing system uses electrical conductivity of the ink to detect when the upper surface level of the ink is lower than the lowest points of the level sensing pads. The upper and lower level sensing pads are electrically connected by a sense resistor (182). A voltage sensor (174) detects across the sense resistor a voltage that depends on the ink conductivity and the position of an upper surface level of the ink with respect to the lowest points of the first and second level pads. The value of the voltage is sent to a CPU (154) that signals a user that a predetermined amount of ink should be added to the reservoir.

Abstract: A drop-on-demand ink jet print head (9) has an ink pressure chamber (22) coupled to a source of ink (11) and an ink drop ejecting orifice (103) with an ink drop ejection orifice outlet (14). An acoustic driver (36), in response to a drive signal (100), produces a pressure wave in the ink and causes the ink to pass outwardly through the ink drop ejecting orifice (103) and the ink jet ejection orifice outlet (14) of the ink jet print head (9). In accordance with the present invention, controlling the operation of the ink jet print head (9) with a particular drive signal reduces print quality degradation resulting from rectified diffusion, which is the growth of .air bubbles dissolved in the ink from the repeated application of pressure pulses to the ink residing within the ink pressure chamber (22) of the ink jet print head (9), such pressure pulses causing the application of pressures below ambient pressure.

Abstract: A FRU assembly (10) comprises a melt chamber (20) including multiple subchambers (30) in which sticks of phase change ink (38, 40) are inserted and melted. Melted ink flows through apertures (54) to a reservoir (28) comprising multiple compartments (56). Each compartment contains a channel (90) and a siphon plate (114) that allow a siphon action that siphons melted ink in the compartments to an orifice (100) that leads to an ink jet print head (16). Heaters (52, 82, and 142) under the control of a CPU (154) melt the ink and keep the melted ink at a desired temperature during various modes of operation.

Abstract: A drop-on-demand ink jet print head (9) has an ink pressure chamber (22) coupled to a source of ink (11) and an ink drop ejecting orifice (103) with an ink drop ejection orifice outlet (14). An acoustic driver (36), in response to a driver signal (100), produces a pressure wave in the ink and causes the ink to pass outwardly through the ink drop ejecting orifice (103) and the ink jet ejection orifice outlet (14) of the ink jet print head (9). In accordance with the present invention, controlling the operation of the ink jet print head (9) with a particular drive signal reduces print quality degradation resulting from rectified diffusion, which is the growth of air bubbles dissolved in the ink from the repeated application of pressure pulses to the ink residing within the ink pressure chamber (22) of the ink jet print head (9), such pressure pulses causing the application of pressures below ambient pressure.