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Viscosity Control Circuit

IP.com Disclosure Number: IPCOM000080995D
Original Publication Date: 1974-Mar-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Ruddy, GA: AUTHOR

Abstract

Changing ink viscosity as a function of temperature is a major factor in altering the velocity and drop spacing of an ink jet stream. A thermoelectric cooling module is arranged to cool or heat the ink, in order to maintain a constant temperature and consequently a reasonably constant viscosity of the ink. Cooling or heating is a function of the ambient temperature so that the ink is always at some specified temperature. It is desirable to perform temperature adjustments on the ink near or actually inside of the ink jet head, so that the temperature of the entire reservoir need not be changed. In addition, it is undesirable to allow the ink enough time to drift from the desired temperature as it flows from the cooling chamber to the nozzle.

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Viscosity Control Circuit

Changing ink viscosity as a function of temperature is a major factor in altering the velocity and drop spacing of an ink jet stream. A thermoelectric cooling module is arranged to cool or heat the ink, in order to maintain a constant temperature and consequently a reasonably constant viscosity of the ink. Cooling or heating is a function of the ambient temperature so that the ink is always at some specified temperature. It is desirable to perform temperature adjustments on the ink near or actually inside of the ink jet head, so that the temperature of the entire reservoir need not be changed. In addition, it is undesirable to allow the ink enough time to drift from the desired temperature as it flows from the cooling chamber to the nozzle.

In the figure, head assembly 1 produces a stream of ink drops 2 that are directed to document 3 in a controlled manner to print information. Ink is supplied from reservoir 4 to head 1 by pump 5. Thermoelectric cooler 6 is used to heat or cool depending upon the direction of the current flow, as determined by control circuits 7. A thermistor or thermocouple 8 is used to monitor the temperature of the ink and provide feedback for the control circuits.

Working with a very small quantity of ink in the region of the head minimizes the heating or cooling requirements, reduces to a minimum the warm-up time at turnon, and minimizes any temperature drift that can occur in the ink after its temperature has been...