Browse Prior Art Database

DUAL SLOPE FLYING POWER SUPPLY ELECTROMETER

IP.com Disclosure Number: IPCOM000024059D
Original Publication Date: 1979-Aug-31
Included in the Prior Art Database: 2004-Apr-02
Document File: 2 page(s) / 267K

Publishing Venue

Xerox Disclosure Journal

Abstract

Figure 1 shows an electrometer circuit which is optimized for machine control applications where it is necessary to measure the voltage on a small test patch imaged on a photoreceptor between document images.

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Page 1 of 2

XEROX DISCLOSURE JOURNAL

DUAL SLOPE FLYING POWER SUPPLY ELECTROM ETER
Robert F~Buchheit

-~500

-~200

3-900

VOLT S

DC

-6O0~

-300

RELAY 2
OPENS

Proposed Classification

U.S~Cl. 324/32 Int. Cl, GOIr 5/28

1COPY SUPPLY VOLTAGE

RELAY 4

               EST SURFACE P0
OPENS T Vc

TO COPIER SUPPLIES

RELAY 2 RELAY 4

COPIER

COPIER

FIG. /

SAMPLE

~LDINPU~

RELAY 4

CLOSES

0T -

8

6

4

2

VOLTS
DC
S~H INPUT

Volume 4 Number 4 July/August 1979 473

RELAY 2 CLOSES

FIG. 2

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

Page 2 of 2

DUAL SLOPE FLYING POWER SUPPLY ELECTROMETER (Cont~d)

Figure 1 shows an electrometer circuit which is optimized for machine control applications where it is necessary to measure the voltage on a small test patch imaged on a photoreceptor between document images.

In the rest position, relay 2 is closed, relay 4 is open and shutter 6 (of a DCFB type electrometer head 8) is closed. Head 8 is being powered from the copier supplies. When the voltage on test surface 10 is to be measured, relay 2 is opened (Head 8 is now powered by the energy stored in capacitors 12 and 14 and the common lead is not tied to the machine ground "flying supply"). Shutter 6 is opened and relay 4 is closed. At this time a relatively large current flows through resistor 16 causing capacitor 18 to be charged toward the copier~shigh voltage supply potential. When capacitor 18 is charged to a voltage more negative than that of test surface 10, the control lead head 8 goes positive relative to the common lead....