Ink-jet print head having improved thermal uniformity

A method for maintaining a predetermined ink temperature profile throughout a multiple-orifice, phase-change ink-jet print head having a rear major surface opposed to a front major surface from which ink is ejected, the print head having a transverse medial axis parallel to the major surfaces and dividing the print head into first and second sides, the method comprising the steps of:

• sensing a first temperature at the first side of the print head;
• applying to the rear surface of the print head through a first print head heating zone a first heat gradient in which more heat is applied to the first side of the print head than to the second side of the print head, the amount of heat applied being related to the first temperature;
• sensing a second temperature at the second side of the print head;
• and
• applying heat to the rear surface of the print head through a second print head heating zone a second heat gradient in which more heat is applied to the second side of the print head than to the first side of the print head, the amount of heat applied being related to the second temperature, whereby the two heat gradients result in a predetermined ink temperature profile throughout a multiple-orifice, phase-change ink-jet print head.

An apparatus for maintaining a predetermined ink temperature profile throughout a multiple-orifice, phase-change ink-jet print head, the print head having a jet section in which the ink jets are positioned and a rear major surface opposed to a front major surface from which ink is ejected, the rear major surface having first and second opposing edges, the apparatus comprising:

• a print head heater attached to the rear surface and including multiple heating zones that produce nonuniform heat output within a zone;
• a thermal break within the print head to thermally insulate the jet section;
• multiple temperature sensors sensing the print head temperature at multiple sensor positions, each of the multiple sensor positions corresponding to one or more of the heater zones;
• and
• a temperature controller controlling the multiple heater zones in accordance with the temperature sensed by the corresponding temperature sensors to maintain a predetermined temperature profile throughout a multiple-orifice, phase-change ink-jet print head.

An apparatus for maintaining a predetermined ink temperature profile throughout a multiple-orifice phase-change ink-jet print head, the print head having a jet section in which the ink jets are positioned and a rear major surface opposed to a front major surface from which ink is ejected, the rear major surface having first and second side margins, the apparatus comprising:

• a print head heater attached to the rear major surface and having first and second ends corresponding to the first and second side margins of the print head, the print head heater including a first heating zone producing more heat at the first end than at the second end and a second heating zone producing more heat at the second end than at the first end;
• a thermal break within the print head to thermally insulate the jet section;
• first and second temperature sensors sensing the print head temperature near the respective first and second side margins of the print head;
• and
• a temperature controller controlling the first and second heater zones in accordance with the temperatures sensed by the respective first and second temperature sensors to maintain a predetermined temperature profile throughout a multiple-orifice, phase-change ink-jet print head.