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SHAPED RESISTORS FOR IMPROVED BUBBLE JET PERFORMANCE

IP.com Disclosure Number: IPCOM000026365D
Original Publication Date: 1991-Aug-31
Included in the Prior Art Database: 2004-Apr-05
Document File: 2 page(s) / 66K

Publishing Venue

Xerox Disclosure Journal

Abstract

At present, bubble jet printheads use rectangular shaped resistors. A bubble is formed over the resistor, which drives a drop out the end of a channel placed over the resistor. The drop velocity at the channel exit is about lOm/sec. The bubble has a dimension of about 1 mil (25 pm) over the resistor at full extension. Since the ink is not compressible, one can estimate the time for bubble expansion as channel dimension (25 pm)/drop velocity (107 pdsec) = 2.5 psec. The pulse length applied to the heater is 2-3 psec in length.

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XEROX DISCLOSURE JOURNAL

SHAPED RESISTORS FOR Proposed Classification IMPROVED BUBBLE JET U.S. C1.346/140R PERFORMANCE Int. C1. GOlD 15/18 William G. Hawkins

At present, bubble jet printheads use rectangular shaped resistors. A bubble is formed over the resistor, which drives a drop out the end of a channel placed over the resistor. The drop velocity at the channel exit is about lOm/sec. The bubble has a dimension of about 1 mil (25 pm) over the resistor at full extension. Since the ink is not compressible, one can estimate the time for bubble expansion as channel dimension (25 pm)/drop velocity (107 pdsec) =
2.5 psec. The pulse length applied to the heater is 2-3 psec in length.

One problem with the present drive scheme is that the bubble expands vertically and displaces ink both forward and backward. By making the distance from the resistor to the back of the channel long, most displacement occurs forward. However, the long length of the channel behind the resistor decreases maximum operating frequency of the channel and the bubble collapse causes damage to the resistor.

The problem is resolved of the shape the resistor is made to make the bubble have a strong horizontal component. A simple design is to make the resistor trapezoidal with the thin end toward the back of the channel. It is anticipated that the bubble would nucleate toward the back of the resistor and move forward. Since the different resistor shape costs nothing, this idea could lead to improved...