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Development And Background Control for Single- And Multi-Color EP Printer

IP.com Disclosure Number: IPCOM000119600D
Original Publication Date: 1991-Feb-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 3 page(s) / 124K

Publishing Venue

IBM

Related People

Lee, MH: AUTHOR [+3]

Abstract

Electrophotography (EP) is a major technology in compact, low-cost, black/white (B/W) and color printing applications. Increasing control of the printing process has led to improvements in the print quality, color balance, and economy of use. A technique which extends earlier control concepts is described here which allows further enhancements in each of these areas. It is embodied in a monitoring device for measuring the amount of toner developed onto both dark and light areas on the imaged photoconductor (PC), and the associated control mechanisms which regulate elements of the toner development system.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 51% of the total text.

Development And Background Control for Single- And Multi-Color EP
Printer

      Electrophotography (EP) is a major technology in compact,
low-cost, black/white (B/W) and color printing applications.
Increasing control of the printing process has led to improvements in
the print quality, color balance, and economy of use.  A technique
which extends earlier control concepts is described here which allows
further enhancements in each of these areas.  It is embodied in a
monitoring device for measuring the amount of toner developed onto
both dark and light areas on the imaged photoconductor (PC), and the
associated control mechanisms which regulate elements of the toner
development system.  It is intended to apply to monocomponent
development; this is a more recent approach to toner development
which does not involve the traditional magnetic bead carrier material
used to transport the toner from the reservoir to the PC.  The use of
monocomponent development is well known for B/W EP printers, and has
been applied to commercial color EP copiers.  For color, the use of a
nonmagnetic monocomponent toner is preferred.

      Key functions which must be controlled in a monocomponent
development system are:  the amount of toner delivered to the PC for
development, the average toner charging which occurs in the
developer, and the distribution of toner charge.  Each will affect
the amount of toner developed on the PC in the desired (imaged) areas
and in the unimaged areas (commonly referred to as background areas).
Certain developer parameters, including applied voltages and
mechanical factors, such as rotational speeds and metering/doctoring
blade pressures, are linked to these key functions.  Hence, a device
which registers the toner deposited on the PC in both imaged and
unimaged areas can allow control of the voltages and mechanical
factors in such a way as to improve the printing process.  The most
notable improvement is, for B/W machines, the reduction in wasted
toner usage as manifested in excessive toner usage in either imaged
or background areas.  These have a major influence on the economics
of EP printing, especially for cartridge-based machines.  For color
printers, both economy of toner usage and (of increasing interest)
color balance/fidelity are improved by increased control of the toner
development.  The reproducibility of rendering a given color, which
may be a mixture of two or more toners applied by separate
developers, requires enhanced process stability and control over the
B/W implementations.

      Described here is the use of the output from an areal
reflectance measurement device to provide increased control of
development.  Small area reflectance devices, sometimes called patch
sensors, have been commonly used in EP printers with dual-component
developers.  These sensors consist of an LED-photodiode pair, with
LED light ente...