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Ribbon Condition Sensor

IP.com Disclosure Number: IPCOM000089546D
Original Publication Date: 1977-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Standiford, JA: AUTHOR

Abstract

Capacitive ink-level detection or sensing systems suffer from a problem which relates to the slow dewetting of the ink from the bottle walls, which leads to an excessively long response time of the sensor and initial erroneous readings. In the system illustrated in Fig. 1, a resistance bridge and an alternating current signal is employed to detect ink bottle signal resistance.

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Ribbon Condition Sensor

Capacitive ink-level detection or sensing systems suffer from a problem which relates to the slow dewetting of the ink from the bottle walls, which leads to an excessively long response time of the sensor and initial erroneous readings. In the system illustrated in Fig. 1, a resistance bridge and an alternating current signal is employed to detect ink bottle signal resistance.

Turning now to Fig. 1, an ink bottle 10 having a supply of ink 11 therein includes a return needle 12 which projects upwardly into a stand pipe 13 in the bottle 10. An ink-level sense probe 14 is mounted in the stand pipe 13 and projects downwardly into the bottle. The tip of the sense probe 14 is positioned at the desired ink height level. A supply needle 15 projects into the bottle and is submerged in the ink. Inasmuch as the ink is conductive, an AC signal fed into the return needle 12 will give a finite resistance through the ink to the supply needle 15, which is grounded, and a simple bridge circuit then can detect when the ink level in the bottle falls below the tip of the ink-level sense probe 14.

A modification of the detector is illustrated in Fig. 2, wherein three possible electrode configurations are schematically illustrated. The electrodes have been labelled A, B and C, and are mounted in an ink reservoir 20 in any one of the configurations illustrated in Figs. 2A-2C. The electrodes are mounted in such a manner that the conductive surfaces of A and C are approximately the same distance from the conductive surface of B and that the conductive surface of A is higher with respect to the bottom of the reservoir than the conductive surfaces of B and C.

Referring now to Fig.3, the resistive...