Recording head for forming images with charged particles

Details Recording head for forming images with charged particles Recording head for forming images with charged particles

1999-04-22

2001-12-25

Gordon, Raquel Yvette (Department: 2853)

Incremental printing of symbolic information

Ink jet

Ejector mechanism

Reexamination Certificate

active

06332670

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a print head for printing images on a reception medium by impinging charged particles on the reception medium.
2. Description of the Related Art
FIG. 1
is a cross-sectional view showing essential configuration of a well known image forming device provided with a recording head.
An image forming device
10
la provided with a toner supply unit
11
, which includes a toner case
13
filled with charged particles, such as toner
12
. A variety of components are provided within the toner case
13
, including a toner supply roller
15
, a toner bearing roller
14
, and a blade
16
. The toner supply roller
15
supplies charged toner to the outer peripheral surface of the toner bearing roller
14
. The toner tearing roller
14
has a cylindrical shape and bears, on its outer peripheral surface, the charged toner supplied by the toner supply roller
15
. The blade
16
regulates the thickness of the toner layer supported on the outer peripheral surface of the toner bearing roller
14
to a uniform layer thickness.
An aperture electrode member
17
formed with a plurality of apertures is disposed above the toner bearing roller
14
. The aperture electrode member
17
is supported with the apertures in confrontation with, and in resilient contact with, the outer peripheral surface of the toner bearing roller
14
. The aperture electrode member
17
is formed with a plurality of electrodes in the vicinity of the apertures. The electrodes are for controlling passage of toner
12
from the outer peripheral surface of the toner bearing roller
14
through the apertures.
Detailed configuration of the aperture electrode member
17
will be described while referring to
FIGS. 2
to
3
(C).
FIG. 2
is a perspective view showing overall configuration of the aperture electrode member
17
.
FIG. 3
(A) is a magnified view showing a portion of the aperture electrode member
17
shown in FIG.
2
.
FIG. 3
(B) is a cross-sectional view taking along a line C—C of
FIG. 3
(A).
FIG. 3
(C) is a magnified view showing an insulation sheet of the aperture electrode member
17
shown in
FIG. 3
(A).
As shown in
FIG. 2
, the aperture electrode member
17
includes an insulation sleet
17
a
and IC chips
17
d
disposed on the insulation sheet
17
a
. The insulation sheet
17
a
is formed from a synthetic resin, such as polyimide, to a thickness of 25 &mgr;m. A plurality of apertures
17
b
are formed through the insulation sheet
17
a
, aligned with a lengthwise direction of the insulation sheet
17
a
. It should be rioted that because the apertures are formed with such a narrow pitch, they are indicated by a straight line in FIG.
2
.
An shown in greater detail in
FIG. 3
(A), the aperture electrode member
17
also includes control electrodes
17
c
provided between adjacent apertures
17
b
, and conductive lines
17
e
for connecting the IC chips
17
d
with the control electrodes
17
c
. With this configuration, the IC chips
17
d
can apply a control voltage to energize the control electrodes
17
c.
As shown in
FIG. 3
(B), a coat layer
17
f
is formed on the lower surface of the insulation sheet
17
a
, that is, on the surface that directly contacts the outer peripheral surface of the toner bearing roller
14
. The coat layer
17
f
is formed mainly from a polyimide type base binder, but also includes carbon as a conductive material, flourine dioxide for reducing friction force, and a charge control agent (CCA).
Returning to
FIG. 1
, the image forming device
10
is also provided with a control circuit
18
, a DC voltage source
20
, a heat roller
22
, a pressure roller
23
, and a cylindrical back electrode roller
19
. The control circuit
18
is for controlling the IC chips
17
. Each IC chip
39
of the aperture electrode member
17
is connected to the control circuit
18
. The cylindrical back electrode roller
19
is rotatably disposed in confrontation with the aperture electrode member
17
and is connected to a DC voltage source
20
. The heat roller
22
and the pressure roller
23
are disposed in confrontation with each other at a position downstream in a transport direction of a reception medium
21
from the back electrode roller
19
.
Next, operations of the image forming device
10
will be described. First, the toner supply roller
15
and the toner bearing roller
14
are rotated in a direction indicated by arrows F
1
and F
2
, respectively, of FIG.
1
. Rotation of the toner supply roller
15
transports toner
12
stored in the toner case
13
toward the toner bearing roller
14
, and scrapes the toner
12
onto the outer surface of the toner bearing roller
14
. Resultant friction charges the toner to a negative charge. Next, the blade
16
regulates the toner
12
borne on the outer peripheral surface of the toner bearing roller
14
into a uniform thin layer. Further rotation of the toner bearing roller
14
convoys the thin layer of toner
12
on the toner bearing roller
14
towards the lower surface of the aperture electrode member
31
. An a result, this toner
12
borne on the outer peripheral surface of the toner bearing roller
14
is supplied to a position beneath the apertures
17
b
while being scraped along the lower surface, that is, the coat layer
17
f
of the aperture electrode member
17
.
The control circuit
18
applies, for example, a positive 40 V voltage to selected ones of the control electrode
17
c
in accordance with inputted image information. Difference in electric potential between the control electrodes
17
c
and the toner bearing roller
14
generates electric lines of force in the vicinity of the apertures
17
b
corresponding to control electrodes
17
c
applied with the voltage by the control circuit
18
. The electric lines of force extend from the control electrodes
17
c
towards the toner bearing roller
14
, whereupon the negatively charged toner
12
borne on the outer peripheral surface of the toner bearing roller
14
is drawn towards the high electric potential near the apertures l
7
b
. The toner
12
that separates from the toner bearing roller
14
in this manner is caught in the electric field formed between the reception medium
21
and the control electrodes
17
c
by a voltage applied to the back electrode roller
19
. The toner
12
is that further drawn toward to, and impinged on, the reception medium
21
to form an image by accumulating an the surface of the reception medium
21
.
A single line's worth of pixels is formed by controlling passage of toner
12
through the apertures
17
b
one time. Once a single line's worth pixels has been formed, the back electrode roller
19
is rotated in a direction indicated by an arrow F
3
in
FIG. 1
, in order to transport the reception medium
21
by a single pixel distance. By repeating the above described processes, all lines of an image can be formed in toner on the reception member
21
. The toner image is then fixed on the surface of the reception member
21
by the heat roller
22
and the pressure roller
23
.
SUMMARY OF THE INVENTION
To form the coat layer
17
f
on the aperture electrode member
17
, a coat liquid, which will form the coat layer
17
f
, is coated directly on the surface of the insulation sheet
17
a
. Then, the entire insulation sheet
17
a
is heated to bake the coat layer
17
f
and the insulation Sheet
17
a
into an integral member. This baking process is performed at a low temperature. For example, when the insulation sheet
17
a
is formed from polyimide, the baking process is performed at 200° C. or less.
However, if the insulation sheet
17
a
and the coat layer
17
f
have different thermal expansion coefficients, then the aperture electrode member
17
can warp due to the differences in thermal expansion when the insulation sheet
17
a
and the coat layer
17
f
are baked integrally together, As a result, materials for both the insulation sheet
17
a
and the coat layer
17
f
need to be made from materials that have the same thermal exp

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