Browse Prior Art Database

BREAKOFF LENGTH DETECTION AND CONTROL

IP.com Disclosure Number: IPCOM000025762D
Original Publication Date: 1987-Dec-31
Included in the Prior Art Database: 2004-Apr-04
Document File: 4 page(s) / 143K

Publishing Venue

Xerox Disclosure Journal

Abstract

stream type ink .j t printing devices having droplet generators with multi-stream arrays, it

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 56% of the total text.

Page 1 of 4

XEROX DISCLOSURE JOURNAL

BREAKOFF LENGTH DETECTION AND CONTROL
Robert A. Lonis

Proposed Classification
U.S. C1.346/75 Int. C1. Gold 15/18

k3,

I____--- 30

10

-

FIG. 1

Volume 12 Number 6 November/December 1987 26 1

[This page contains 1 picture or other non-text object]

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BREAKOFF LENGTH DETECTION AND CONTROL(Cont'd)

In continu 1

lengths (B.

VSENSE

CASE 1 : DROPS IN OPICAL GAP CAUSE

PULSING OF VSENSE. INDICATING
B.O.L. IS
TOO SHORT

CASE 2 : B.O.L. IN OPICAL GAP CAUSES

0 STEADY STATE OF VSENSE = + V +

1

FIG. 2

         stream type ink .j t printing devices having droplet generators with multi-stream arrays, it <s essential to maintain the point at which droplet break off of each stream occurs within some specified range due to droplet char ing restrictions. Some existing approaches for assuring break off

observation, then modifying the synchronizing drive amplitude of the piezoelectric driver in the acoustic ink cavity of the droplet generator. By developing a knowledge of the 30 limits around a mean B.O.L. for a droplet generator at a fixed operating point, it has been assumed that one can design an array of charging tunnels to encompass the empirical variations in all
B.O.L.'s, thus ensuring satisfactory charging of all jets in the array over long periods of time. This assumption is limited in that it cannot handle either a short or long term variation outside the 30 limits due to factors such as jet start-up, sound speed changes from varying air content in the ink, etc. Therefore, a time period must be allowed for system "cold starts". Accordingly, the overall reliability of the ink jet printhead is reduced because of a lack of predictability for short term process physics perturbations.

8 .L.'s) include the removal of the deflection components for

In Figure 1, a closed loop feedback control system is shown consisting of a
B.O.L. sensor 10, control algorithm as delineated in Table 1 below, and synchronizing drive amplitude modulation of driver 12 for the piezoelectric transducer 14 of the droplet generator 16. All B.O.L.'s can be maintained within a desired range for both short term and long term process physics perturbations with this control system. A major assumption is, of course, that

262 XEROX DISCLOSURE JOURNAL

Volume 12 Number 6 November/December 1987

[This page contains 1 picture or other non-text object]

Page 3 of 4

BREAKOFF LENGTH DETECTION AND CONTROL(Cont'd)

the B.O.L. signature for the streams 18 in the array does not change...