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AN AC IMPEDANCE BRIDGE FOR MONITORING MATERIAL IN A DEVELOPER OR TONER CONTAINER

IP.com Disclosure Number: IPCOM000027742D
Original Publication Date: 1999-Apr-30
Included in the Prior Art Database: 2004-Apr-09
Document File: 8 page(s) / 292K

Publishing Venue

Xerox Disclosure Journal

Abstract

Disclosed is the use of an Alternating Current (AC) Impedance Bridge in an electrophotographic printing machine that detects the presence of a developer or toner container and its fill level. The device functions with ferromagnetic developer, toner, or mixtures thereof in a powdered or liquid state.

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XEROX DISCLOSURE JOURNAL

AN AC IMPEDANCE BRIDGE FOR MONITORING MATERIAL IN A DEVELOPER OR TONER CONTAINER
J. Stephen Kittelberger

Proposed Classification
U. S. C1. 399/358 Int. C1. G03g 21/10

D

FIG. 7

XEROX DISCLOSURE JOURNAL - Vol. 24, No. 2 MarcWApril 1999 85

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AN AC IMPEDANCE BRIDGE FOR MONITORING MATERIAL IN A DEVELOPER OR TONER CONTAINER (Cont'd)

f"

24

74

I

FIG. 2

86 XEROX DISCLOSURE JOURNAL - Vol. 24, No. 2 MarcWApril 1999

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AN AC IMPEDANCE BRIDGE FOR MONITORING MATERIAL IN A DEVELOPER OR TONER CONTAINER (Cont'd)

5.0

4.0

DISPLAY VOLTAGE 3.0

(VOLTS)

2 .o

1 .o

 I 1- I I 100 200 300 400
QUANTITY OF TONER PARTICLE IN CONTAINER

(GRAM)

FIG. 3

Disclosed is the use of an Alternating Current (AC) Impedance Bridge in an electrophotographic printing machine that detects the presence of a developer or toner container and its fill level. The device functions with ferromagnetic developer, toner, or mixtures thereof in a powdered or liquid state.

Figure 1 shows an impedance bridge 10 being driven by a generator 12 connected between nodes A and C. The impedance bridge 10 comprises four impedance devices Z1,

XEROX DISCLOSURE JOURNAL - Vol. 24, No. 2 MarcWAprill999 87

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AN AC IMPEDANCE BRIDGE FOR MONITORING MATERIAL IN A DEVELOPER OR TONER CONTAINER (Cont'd)

Z2,Z3, and Z4. If the impedance bridge 10 is balanced, no current flows through a detector 14 connected between nodes D and B. This results in the relationship

                       2, @Z4 = 2, @Z3 Since Z1, Z2,Z3, and & are AC components of complex quantities, they are equal only if their magnitude and phase angles are equal to each other respectively. It then follows that two adjustments are necessary to satisfy the condition of balance. However, if Z1 and 23 are pure resistances (R1, R3) and Z2 and & are pure inductors (L2, L4), a relationship requiring one adjustment to satisfy the condition of balance can be written as

An impedance bridge 20 comprised of inductors L2 and L and resistors R1 and R3 is illustrated in Figure 2. L4 and L2 are both comprised of 300 turns of an insulated wire, preferably 30HVYARMPTC. Resistors R3 and R1 are selected to both have a resistance value of 4K ohms. A fixed frequency oscillator 22 connected between nodes A and C supplies an alternating current voltage to the impedance bridge 20. An amplifier 24 whose output is proportional to the potential difference between nodes B and D passes a signal to the indicator 14 that visually displays a balanced null or out of balance condition. A balanced null exists when L4 equals L2, if R3 and R1 provide a 1: 1 ratio.

Referring further to Figure 2, inductor Lz of the impedance bridge 20 is contained in printing machine 40 along with resistors R3 and R1, oscillator 22, amplifier 24, and the detector 14. The inductor L4 is molded into the body of...