Printing – Rolling contact machines – Rotary
Reexamination Certificate
2000-07-27
2002-04-09
Colilla, Daniel J. (Department: 2854)
Printing
Rolling contact machines
Rotary
C101S232000
Reexamination Certificate
active
06367379
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
This invention relates to a double-sided printing apparatus and a double-sided printing method suitable for use for printing on front and rear surfaces of continuous recording paper, for example, by an electrophotographic method.
2) Description of the Related Art
In recent years, in a field of development of printers for continuous recording paper (a continuous medium), various double-sided printing apparatus have been placed on the market from various manufacturers. A double-sided printing apparatus is an apparatus for printing on both of the front surface and the rear surface of continuous recording paper by an electrophotographic method and includes two printers each of which can print on one surface of continuous recording paper and are connected to each other via a turn bar for turning over the continuous recording paper.
FIG. 12
is a schematic view of a double-sided printing apparatus. Referring to
FIG. 12
, the double-sided printing apparatus
80
shown includes a pair of printers
80
a
and
80
d
, a turn bar
80
b
, and a transport relaying apparatus
80
c
. Continuous recording paper
100
is printed on the front surface thereof by the printer
80
a
and turned over by the turn bar
80
b
. Then, the continuous recording paper
100
is transported through the transport relaying apparatus
80
c
and then printed on the rear surface thereof by the printer
80
d
. In this manner, the front and rear surfaces of the continuous recording paper
100
are printed by the two printers
80
a
and
80
d
which are connected to each other.
FIG. 13
is a schematic view of the printer
80
d
. The printer
80
d
shown in
FIG. 13
prints on the rear surface of the continuous recording paper
100
discharged from the transport relaying apparatus
80
c
, and the continuous recording paper
100
released from the transport relaying apparatus
80
c
is loaded into the printer
80
d
. Then, the continuous recording paper
100
is transported by a tractor unit
95
which includes a pair of tractor belts
95
a
and
95
c
and a tractor motor
95
b
. During such transportation, toner powder sticking to a photosensitive drum
90
e
is transferred to the continuous recording paper
100
by a transfer charger (not shown) provided in the tractor unit
95
so that a print image is formed on the continuous recording paper
100
. Then, the toner powder is fixed to the continuous recording paper
100
by heat in a flash fixing unit
91
. Thereafter, the continuous recording paper
100
is stored into a paper folding unit
94
b
under the guidance of a pair of scuff rollers
92
b
and
92
a
. The scuff rollers
92
b
and
92
a
are rotating at an equalvelocity. A pair of pinch rollers
93
a
and
93
b
cooperate with the scuff rollers
92
a
and
92
b
, respectively, to transport the continuous recording paper
100
.
As a mechanism for transporting the continuous recording paper
100
, the tractor unit
95
shown in
FIG. 13
serves as main transport means for transporting the continuous recording paper
100
and the scuff rollers
92
b
and
92
a
take up the continuous recording paper
100
.
Meanwhile, toner power is transferred to a surface of the continuous recording paper
100
in accordance with a following flow. Referring to
FIG. 13
, the photosensitive drum
90
e
rotates in the clockwise direction. During rotation, the surface of the photosensitive drum
90
e
is first charged uniformly by a precharger
90
c
, and then, an electrostatic latent image of data to be printed is formed on the surface of the photosensitive drum
90
e
by exposure to light by an exposure station
90
d
. Then, the electro static latent image is developed into a toner image by a developing unit
90
g
, and the toner powder on the photosensitive drum
90
e
is transferred to the surface the continuous recording paper
100
by the transfer charger in the tractor unit
95
. Meanwhile, remaining toner powder on the photosensitive drum
90
e
is removed by a cleaner station
90
b
. Then, the surface of the photosensitive drum
90
e
is charged uniformly by the precharger
90
c
again in order to prepare for a next transferring step.
Now, velocity variations of the tractor motor
95
b
in the tractor unit
95
and scuff motors in the scuff rollers
92
b
and
92
a
are described with reference to FIGS.
14
(
a
),
14
(
b
) and
15
(
a
),
15
(
b
), and also operation for keeping the tensile force of the continuous recording paper
100
is described. It is to be noted that the transport velocity of the tractor unit
95
is hereinafter referred to as main transport velocity, and the transport velocity of the scuff rollers
92
b
and
92
a
is hereinafter referred to as scuff transport velocity. Further, the direction along which the continuous recording paper
100
is printed and transported may be hereinafter referred to as forward direction or printing transport direction, and the direction opposite to the direction may be hereinafter referred to as reverse direction.
FIG.
14
(
a
) is a diagram illustrating the velocity variation of the tractor motor upon starting of printing, and FIG.
14
(
b
) is a diagram illustrating the velocity variation of the scuff motors upon starting of printing. The characteristic illustrated in FIG.
14
(
a
) is a characteristic of the tractor motor
95
b
in the tractor unit
95
, and the characteristic illustrated in FIG.
14
(
b
) is a characteristic of the scuff motors (not shown) for driving the scuff rollers
92
b
and
92
a.
In a section denoted by A in FIG.
14
(
b
), the scuff rollers
92
b
and
92
a
are started earlier than the tractor unit
95
to increase the tension of the continuous recording paper
100
(stretch the continuous recording paper
100
in a taut state). Also during printing, in order to assure a high tension to the continuous recording paper
100
, the scuff transport velocity is set higher by approximately 5 to 30% than the main transport velocity.
FIG.
15
(
a
) is a diagram illustrating the velocity variation of the tractor motor upon stopping of printing, and FIG.
15
(
b
) is a diagram illustrating the velocity variation of the scuff motors upon stopping of printing. A velocity curve
90
a
shown in FIG.
15
(
a
) indicates the main transport velocity. In FIG.
15
(
a
), the tractor motor first rotates in the forward direction at a velocity V
1
and then rotates reversely at another velocity −V
2
after the velocity becomes equal to zero. Here, both of V
1
and V
2
are positive values. The reason why the rotation is reversed is that it is intended to adjust the printing position of the continuous recording paper
100
to a position suitable when next printing is to be started.
Meanwhile, the velocity curve
90
b
′ shown in FIG.
15
(
b
) indicates the scuff transport velocity. The scuff transport velocity exhibits such a variation that the scuff motor continues to rotate forwardly at a velocity higher by approximately 5 to 30% than the main transport velocity and still continues its forward rotation even after the tractor unit
95
starts its backward transportation, and then stops after the tractor unit
95
stops its backward transportation. Therefore, in a section denoted by B in FIG.
15
(
b
), the scuff rollers
92
b
and
92
a
rotate forwardly so that the continuous recording paper
100
is taken up by them and a predetermined tension of the continuous recording paper
100
is obtained thereby.
As described above with reference to FIGS.
14
(
a
),
14
(
b
),
15
(
a
) and
15
(
b
), the scuff rollers
92
b
and
92
a
operate to increase the tension of the continuous recording paper
100
. In other words, they operate in such a manner as described in the following paragraphs {circle around (
1
)} to {circle around (
3
)}.
{circle around (
1
)} During printing, the scuff rollers
92
b
and
92
a
are set in an excessively feeding condition wherein the scuff velocity is higher by approximately 5 to 30% than the main transport velocity so that the continuous recording paper
100
may
Armstrong Westerman & Hattori, LLP
Colilla Daniel J.
Fujitsu Limited
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