COPIER (DEVELOPMENT CURRENT SENSING)
Original Publication Date: 1978-Apr-30
Included in the Prior Art Database: 2004-Mar-31
Xerox Disclosure Journal
In some forms of xerographic development, a developer current flows between the applicator and photoreceptor during develop-ment of the image on the photoreceptor, A current controlling circuit is provided for automatically adjusting and main-taming such a current.
XEROX DISCLOSURE JOURNAL
COPIER (DEVELOPMENT CURRENT
Peter Frederick Clark
U.S. Cl. 118/653
mt. Cl. G03g 15/08
In some forms of xerographic development, a developer current
flows between the applicator and photoreceptor during develop-~
ment of the image on the photoreceptor, A current controlling
circuit is provided for automatically adjusting and main~
taming such a current.
In operation of the circuit, the switch (8) is initially
closed so that the capacitor (19) is fully charged. The
output of the comparator (1) holds the transistor (14) ON.
Current flowing through the zener diode (12) and the transis~
tor (13) ensures that the transistor (10) is ON, The currents
flowing through the transistor (10) and (14) discharge tt'ie
capacitor (19) and the voltage of the busbar (3) falls so
reducing the bias on the applicator roll of the copier which
is connected to terminal (A)
Volume 3 Number 2 March/April 1978 97
COPIER (DEVELOPMENT CURRENT SENSING) (Cont~d)
Developer current begins to flow through the resistor (20) and
develops a voltage across the resistor (2) . The desired
developer current for mid~grey is previously calibrated for
the development system of the copier and corresponds to a
voltage difference set on the potentiometer (4) . The capac~
itor continues to discharge and the developer current con~
tinues to increase until the input voltages at the c...