METHODE DE FIXATION DE TONER

TONER FIXING METHOD

Abrégé anglais

ABSTRACT OF THE DISCLOSURE
In a toner fixing method employing multiple irradiation by light
of a flash discharge lamp in electronic duplicating machines, the repetitive
frequency of irradiation is selected in the range of 1.2 to 3.5 Hz so that
repeated energization of the lamp does not exert a bad influence on the
service life of the lamp and its lighting device.

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A toner fixing method employing irradiation by light of a flash
discharge lamp in electronic duplicating machines, in which the frequency
of irradiation is defined in the range of 1.2 to 3.5 Hz.

Description

This invention relates to a toner fixing method in an electrostatic
type recording instrument, such as an electronic duplicating machine or the
lilce.
For fixing a toner in electronic duplicating machines, use has long
been made of an infrared lamp or heater; and in recent years, it has been pro-
posed to employ, for this purpose, irradiation by light of a flash discharge
lamp.
The two methods have merits and demerits, and the latter still have
many problems remaining unsolved. For example, a minimum value of energy
1~ necessary for fixing the toner depends on the size of paper on which the
toner is to be fixed; but, it is still unknown what method is optimum for
providing the energy by irradiation using a flash discharge lamp.
This invention is based on the findings that it is better to provide
the energy for the toner fixation by irradiating a plurality of times rather
than once and that definition of the frequency of irradiation in a certain
range provides favorable results. The present invention has for its object
to provide a toner fixing method which does not shorten the lifetime of a
flash discharge lamp and its lighting circuit.
Briefly stated, in the toner fixing method of this invention, the
toner is fixed by multiple irradiation using a flash discharge lamp, and the
frequency of irradiation is selected in the range of 1.2 to 3.5 Hz.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Letting E represent the energy necessary for fixing a toner, 1CV
represent the energy of one irradiation and f(Hz) represent the frequency
of irradiation, they bear the following relationship:

1/2CV = E/f
In the multiple irradiation the frequency f is an important factor for the
toner fixation.
If the frequency f is too high, there is not sufficient time to
allow cooling of a discharge capacitor of a lighting device; therefore, to
suppress a temperature rise of the discharge capacitor, the frequency must
be defined. Conversely, if the frequency f is too low, the energy of one
irradiation l/2CV must be increased; but this results in the ser~ice life
of the flash discharge lamp becoming short. At any rate, it is preferred to
define the upper and lower limits of the frequency f. For instance, in the
case where l/2CV = 250 joules, irradiation is performed three times in
two seconds and the entire energy to the toner fixation is 250 x 3 = 750
joules, the temperature rise of the discharge capacitor is held below 10 C,
and the flash discharge lamp withstands more than five million energization
times. In this case, the frequency f is 1.5.
As a result of investigation of the frequency f to obtain a temp-
erature rise of less than 10 C for the discharge capacitor and a lifetime
of five million times of energization for the flash discharge lamp, it has
been found that f~3.5 allows a temperature rise up to about 20 C and hence is
not preferred, that f~ 1.2 results in a lifetime of about three million times
of energization and hence is also undesirable and that 1.2 C f ~ 3.5 ensures
toner fixation without shortening the service life of the flash discharge
lamp and its lighting circuit.
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Therefore, in the toner fixing method of the present invention, the
frequency of irradiation is selected in the range of 1.2 to 3.5 Hz; accord-
ingly, the method of this invention is of great utility when put to use.