Niels Norby Nielsen DeceasedOakland, CA

5682186, Oct 28, 1997

Mar 10, 1994

8/209091

Jaime H. Bohorquez - Escondido CA
Charles E. Schinner - San Diego CA
John H. Dion - Corvallis OR
Arthur R. Hart - Corvallis OR
Niels J. Nielsen - Corvallis OR

Hewlett-Packard Company - Palo Alto CA

B41J 2165

347 29

An ink pen is provided with a protective capping apparatus to protect against damage caused by the ingress of dirt and debris, the accumulation or solidification of ink, the discharge of static electricity or the like. The protective capping apparatus has a protective cap movable between an open position and a closed position. In the closed position the protective cap shields a portion of an ink pen such as the ink-jets or the electrical contacts.

5418558, May 23, 1995

May 3, 1993

8/057943

Scott W. Hock - San Diego CA
David A. Johnson - Bonsall CA
Niels J. Nielsen - Corvallis OR

Hewlett-Packard Company - Palo Alto CA

B41J 205

347 14

A method for operating a thermal ink jet printer including a printhead having ink firing heater resistors responsive to pulses provided to the printhead. A sequence of pulse bursts of respective increasing or decreasing pulse energies that span a predetermined pulse energy range is applied to the printhead, each pulse burst comprised of a plurality of pulses having a pulse energy that is associated with such pulse burst and is constant for all pulses in such burst, and each burst having a sufficient number of pulses to allow the printhead to achieve a steady state operating temperature at the pulse energy of the pulse burst. A steady state operating temperature sample is determined for each of the sequence of pulses bursts of different pulse energies to produce a set of temperature samples respectively associated with the increasing pulse energies, and a turn on pulse energy is determined from the temperature samples. The thermal ink jet printhead is then operated with a pulse energy that is greater than the turn on pulse energy and in a range that provides a desired print quality while avoiding premature failure of the heater resistors.

5459498, Oct 17, 1995

Nov 30, 1992

7/982813

Dana Seccombe - Foster City CA
Niels J. Nielsen - Corvallis OR
King-Wah W. Yeung - Cupertino CA
Lawrence A. Hand - Palo Alto CA

Hewlett-Packard Company - Palo Alto CA

B41J 205
B41J 29377

347 18

An ink-cooled thermal ink jet printhead has an efficient heat exchanger located on the back side of the printhead that eliminates the need for heat sinks. All ink flowing to the firing chamber goes through the heat exchanger. The geometry of the heat exchanger is chosen so that almost all the residual heat absorbed by the printhead substrate is transferred to the ink as it flows to the firing chamber. Additionally, the pressure drop of the ink flowing through the heat exchanger is low enough so that it does not significantly reduce the refill rate of the firing chambers. The heat exchanger can have one or more active heat exchanger sides. The heat exchanger has little thermal mass itself and significantly reduces the thermal mass of printhead by eliminating the need for a heat sink. This reduces the warm-up time of the printhead to a fraction of a second.

5657061, Aug 12, 1997

Jul 11, 1995

8/501219

Dana Seccombe - Foster City CA
Niels J. Nielsen - Corvallis OR
King-Wah Walter Yeung - Cupertino CA
Lawrence A. Hand - Palo Alto CA

Hewlett-Packard Company - Palo Alto CA

B41J 205

347 18

An ink-cooled thermal ink jet printhead has an efficient heat exchanger located on the back side of the printhead that eliminates the need for heat sinks. All ink flowing to the firing chamber goes through the heat exchanger. The geometry of the heat exchanger is chosen so that almost all the residual heat absorbed by the printhead substrate is transferred to the ink as it flows to the firing chamber. Additionally, the pressure drop of the ink flowing through the heat exchanger is low enough so that it does not significantly reduce the refill rate of the firing chambers. The heat exchanger can have one or more active heat exchanger sides. The heat exchanger has little thermal mass itself and significantly reduces the thermal mass of printhead by eliminating the need for a heat sink. This reduces the warm-up time of the printhead to a fraction of a second.