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Hystersis Correction for Thermal Wax Transfer Printing

IP.com Disclosure Number: IPCOM000117990D
Original Publication Date: 1996-Aug-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 4 page(s) / 86K

Publishing Venue

IBM

Related People

Lee, HC: AUTHOR

Abstract

In thermal wax transfer printing, dots are formed by applying spot heat to wax ribbon which is in close contact with paper. The heat is generated by a resistor element of stylus. The writing head has an array of this thermal styli typically at 300 elements per inch interval. The ink-wax transfer takes place only at above a threshold temperature and there is an optimum temperature to form a particularly desired spot size. The energy level (pulse width/amplitude) to reach the desired stylus temperature in a specified time period for given paper speed varies with the pattern being printed. At cold start, higher input energy is required, but during continuous printing, much lower input energy is needed for the stylus. Also, whether adjoining dots are printed or not affects the required input energy level.

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Hystersis Correction for Thermal Wax Transfer Printing

      In thermal wax transfer printing, dots are formed by applying
spot heat to wax ribbon which is in close contact with paper.  The
heat is generated by a resistor element of stylus.  The writing head
has an array of this thermal styli typically at 300 elements per inch
interval.  The ink-wax transfer takes place only at above a threshold
temperature and there is an optimum temperature to form a
particularly desired spot size.  The energy level (pulse
width/amplitude) to reach the desired stylus temperature in a
specified time period for given paper speed varies with the pattern
being printed.  At cold start, higher  input energy is required, but
during continuous printing, much lower input energy is needed for the
stylus.  Also, whether adjoining dots are  printed or not affects the
required input energy level.  This phenomenon  is known as "hystersis
effects" in the art.  Elaborate schemes are required to correct these
hystersis effects involving study of the pulse  history prior to the
present pulse and adjoining dot pattern. Simpler  techniques of the
preheating concept are described below.

      The important parameter is the stylus temperature when the
stylus is energized.  For single column printing, in the steady state
of continuous printing, the stylus temperature is at T sub L prior
to being turned on.  This is the temperature below the transfer
threshold, T sub o, but above the cold or ambient temperature T sub a
(Fig. 1B).  When the heating element is turned on for the duration t
sub s, the stylus temperature rises to transfer temperature, T sub t,
above the threshold and ink is trans...