Developer regulating member and method of molding the same

Details Developer regulating member and method of molding the same Developer regulating member and method of molding the same

2000-07-20

2003-03-04

Resan, Stevan A. (Department: 1773)

Stock material or miscellaneous articles

Web or sheet containing structurally defined element or...

Physical dimension specified

C399S284000

Reexamination Certificate

active

06528158

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a developing unit in an image forming apparatus such as an electrophotographic copying machine or electrophotographic printer and, more particularly, to a developer regulating member adopted in a one-component developing unit which performs development by using a one-component developer, and a method of molding the same.
BACKGROUND OF THE INVENTION
In a conventional electrophotographic image forming apparatus, an electrostatic latent image formed on an image carrier is made visible as a toner image by a developing unit.
As one such conventional developing unit, for example, a developing apparatus shown in
FIG. 8
is known, in which a developer carrying member
103
(to be referred to as a developing sleeve hereinafter) is rotatably attached to a developer container
102
at a small distance from an electrophotographic photosensitive drum
101
rotatably supported by an apparatus main body. A developer regulating member
104
and elastic roller
105
are abutted against the developing sleeve
103
. Toner
106
serving as a one-component developer is contained in the developer container
102
.
In this conventional developing unit, as a means for regulating small the layer thickness of the toner
106
carried and conveyed to the developing unit by the developing sleeve
103
, the developer regulating member
104
made of rubber or a metal is abutted against the developing sleeve
103
. The toner
106
is regulated as it is passed through the abutting portion between the developer regulating member
104
and developing sleeve
103
, so that a thin film of the toner
106
is formed on the developing sleeve
103
. Also, triboelectricity for developing the latent image is applied to the toner
106
by friction at the abutting portion.
To form the thin film coating with the toner
106
on the developing sleeve
103
, since the particles of the toner
106
exist with a distribution range of several
&mgr;m
to ten-odd
&mgr;m
, when development is to be performed by using the developer regulating member
104
and developing sleeve
103
, the following two factors are particularly important.
First, it is important to urge the developer regulating member
104
against the ridge portion on the surface of the developing sleeve
103
uniformly and highly precisely so that the toner
106
sandwiched between the developing sleeve
103
and developer regulating member
104
is uniformly charged by friction, and simultaneously to form a uniform thin layer on the developing sleeve
103
. For this purpose, the developer regulating member
104
must have a high flatness.
Second, it is important not to form a partial streaking nonuniformity in the thin layer on the developing sleeve
103
. For this purpose, the developer regulating member
104
which urges against the developing sleeve
103
must have a small surface roughness.
When the developer regulating member
104
is made of a metal, it has a high modulus of elasticity. The urging force accordingly fluctuates largely in accordance with the urging conditions, and a preset pressure is difficult to control. Since the developer regulating member
104
is a rigid body, it is difficult to urge it uniformly along the ridge of the sleeve, and a streaking nonuniformity in the coating and the like tends to be formed on the developing sleeve
103
by partial defective urging.
When the developer regulating member
104
is made of rubber, it has a lower modulus of elasticity than the developer regulating member
104
made of a metal. The urging force accordingly fluctuates less in accordance with the urging conditions, and the preset pressure can be controlled easily. However, since this developer regulating member
104
is soft, it is difficult to set the urging position against the developing sleeve
103
. When the developer regulating member
104
is used over a long period of time, creep is produced by plastic deformation in rubber to decrease the preset pressure, affecting the development efficiency.
As a countermeasure, as shown in
FIG. 9
, it is proposed to form a developer regulating member
104
from an elastic blade
107
and metal thin plate
108
, and to stack the elastic blade
107
made of rubber or the like on the metal thin plate
108
with an adhesive
109
. To stack this developer regulating member
104
, the elastic blade
107
molded in advance to form a rubber piece is adhered through the adhesive
109
, or the metal thin plate
108
is mounted and arranged in a mold in advance, and raw material rubber is charged into the mold and uniformly and thermally formed with a hot press. In recent years, a method of mounting and arranging a metal thin plate in a mold in advance, and injection-molding a thermoplastic elastomer in the mold is proposed, as described in Japanese Patent Laid-Open No. 8-95377.
In the developer regulating member
104
in this conventional injection molding, a gate
110
for resin injection is formed at substantially the center of the long-side end face of the elastic blade
107
, as shown in
FIG. 5
, and a runner
111
is so formed as to continue to the gate
110
. This runner
111
is a cold runner. The elastic blade
107
to be formed by charging the resin has a thin, elongated shape with a thickness of approximately 1 mm and a length of approximately 200 mm or more. The runner
111
minimizes the length of a resin flow path, thereby eliminating defective charging. If the runner
111
is a hot runner, a portion near the gate
110
thermally shrinks greatly due to the heat of the hot runner. Also, since the gate
110
is located on the long-side end face, its heat shrinkage degrades the flatness of the elastic blade
107
.
The metal thin plate (e.g., phosphor bronze; 1.8×10
−6
/° C.) and thermoplastic elastomer (e.g., polyamide-containing elastomer diamide PAE E40[manufactured by DAICEL-HULS]; 1.5×10
−4
/° C.) that form the developer regulating member
104
have largely different coefficients of linear expansion. Therefore, when the thermoplastic elastomer is injected into a mold, in which the metal thin plate
108
coated with a primer is mounted and arranged in advance, to integrally mold the elastic blade
107
, since shrinkage of the thermoplastic elastomer during cooling solidification is much larger than that of the metal thin plate
108
, the thermoplastic elastomer on the metal thin plate
108
is fixed to the metal thin plate
108
with the primer, as shown in
FIG. 6
, and distortion during molding remains near the gate
110
. Distortion
112
accordingly occurs between the metal thin plate
108
and gate
110
in a direction perpendicular to the long side of the elastic blade
107
. This appears as a streaking nonuniformity in the coating on the developing sleeve
103
produced by partial defective urging.
As shown in
FIG. 7
, the resin flow changes its flowing direction after it abuts against the long side of the elastic blade
107
on the metal thin plate
108
side. As a result, a flow mark
113
is formed in the hatched portion in
FIG. 7
on the surface of the elastic blade
107
.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above problems, and has as its object to provide a method of molding a developer regulating member having an elastic blade with a high flatness and small surface roughness, and a developer regulating member which uniformly charges toner by friction and which does not form partial streaking nonuniformity in a uniform thin layer on a developing sleeve.
In order to achieve the above object, according to the present invention, there is provided a developer regulating member obtained by integrally forming a metal thin plate with spring elasticity and an elastic blade by injection molding or injection compression molding, characterized in that a resin injection gate for the elastic blade is formed on a short-side end face of the elastic blade.
The developer regulating member according to the present invention is characterized in that a sacrificial gate is formed o

Affiliated with

Also associated with

Rating

Developer regulating member and method of molding the same does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Developer regulating member and method of molding the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Developer regulating member and method of molding the same will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3017487