Electrophotography – Image formation – Fixing
Reexamination Certificate
1999-04-22
2001-12-11
Grimley, Arthur T. (Department: 2852)
Electrophotography
Image formation
Fixing
C219S216000, C399S328000, C399S068000
Reexamination Certificate
active
06330419
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fixing apparatus which performs a fixing treatment of a recording medium bearing an image which has not been fixed and an image forming apparatus which is equipped with the fixing apparatus.
2. Related Background Art
There is conventionally known and put to practical use a fixing apparatus
100
equipped, as shown in
FIG. 11
, with a fixing rotary body
102
which is in contact with a non-fixed image bearing surface of a recording medium
101
, a press rotary body
103
which is in pressure contact with the fixing rotary body
102
through the recording medium
101
, and a plurality of sheet discharge rotary body pairs
104
which nip, convey and discharge the recording medium
101
subjected to a fixing treatment out of a fixing apparatus main body: each of the sheet discharge rotary body pairs
104
including an upper rotary body
105
which is to be in contact with the surface of the recording medium
101
and a lower rotary body
106
which is in pressure contact with the upper rotary body
105
through the recording medium
101
.
FIG. 11
is a schematic front view showing an outline of a configuration of the fixing apparatus
100
.
Speaking concretely of the fixing apparatus
100
, the recording medium
101
which bears a non-fixed image is subjected to the fixing treatment while passing between the fixing rotary body
102
and the press rotary body
103
, and nipped and conveyed by the plurality of upper rotary bodies
105
and the lower rotary bodies
106
which are rotating in the same direction as the fixing rotary body
102
and the press rotary body
103
, thereby being discharged out of the fixing apparatus main body.
Furthermore, since the upper rotary bodies
105
which are brought into contact with a developer beared by the recording medium
101
which has been subjected to the fixing treatment, a fluoroplastic is used as a surface material for the upper rotary bodies
105
to prevent the developer from adhering to surfaces of the upper rotary bodies
105
.
In the recent years where the speeding up of an image forming process is progressed, a passage from a fixing nip formed between the fixing rotary body and the press rotary body to a sheet discharge nip formed between the upper rotary body and the lower rotary body tends to be shortened as a measure to speed the an image forming process.
However, the conventional fixing apparatus
100
in which rotating shafts of the upper rotary bodies
105
are in parallel with rotating shafts of the fixing rotary body
102
and the press rotary body
103
as shown in
FIG. 11
can hardly prevent a semi-melted developer on the recording medium
101
having been subjected to the fixing treatment from adhering to surfaces of the upper rotary bodies
105
even if a fluoroplastic is adopted as the surface material for the upper rotary bodies
105
.
In particular, there is a tendency to use developers which have low melting points as a measure to speed the image forming process and it is extremely difficult to prevent such developers having low melting points from adhering to the surfaces of the upper rotary bodies.
SUMMARY OF THE INVENTION
In view of the circumstances described above, a primary object of the present invention is to provide a fixing apparatus which is capable of facilitating to prevent a semi-melted developer on a recording medium from adhering to surfaces of upper rotary bodies or an image forming apparatus which is equipped with the fixing apparatus.
The present application makes it possible to accomplish the object described above by a first invention, which is a fixing apparatus configured to perform a fixing treatment of a recording medium bearing a non-fixed image on one surface thereof by heating the recording medium with a heating body while passing the recording medium between a fixing rotary body and a press rotary body which are in pressure contact with each other and rotatable, and comprising pairs of sheet discharge rotary bodies which are in pressure contact with each other through the recording medium, and nip and convey the recording medium after the fixing treatment to discharge the recording medium out of a fixing apparatus main body: the pairs of paper discharge bodies including upper rotary bodies to be in contact with one surface of the recording medium and lower rotary bodies to be in contact with the other surface of the recording medium, wherein at least the upper rotary bodies are set to apply conveying forces to the recording medium in directions which are on a plane in parallel with the surface of the recording medium and inclined relative to a recording medium conveying direction between the fixing rotary body and the press rotary body.
Furthermore, the present application makes it possible to accomplish the object described above by a second invention, wherein a recording medium conveying speed between the upper rotary bodies and the lower rotary bodies is set higher than a recording medium conveying speed between the fixing rotary body and the press rotary body in the first invention according to the present application.
Furthermore, the present application makes it possible to accomplish the object described above by a third invention, wherein rotating axial directions of the upper rotary bodies are set in directions which are on a plane in parallel with a surface of the recording medium and inclined relative to axial directions of rotating shafts of the fixing rotary body and the press rotary body in the first invention or the second invention according to the present application.
Furthermore, the present application makes it possible to accomplish the object described above by a fourth invention, wherein a through bore which has an inside diameter continuously enlarged from an end to the other end in a rotating axial direction is formed in each upper rotary body, a shaft body which rotatably supports the upper rotary body is inserted into the through bore and the shaft body has an outside diameter which is smaller than a small diameter of the through bore in the first invention or the second invention according to the present application.
Furthermore, the present application makes it possible to accomplish the object described above by a fifth invention, wherein each upper rotary body is configured to have an outside diameter which is continuously enlarged from an end to the other end in a rotating axial direction in the first invention or the second invention according to the present application.
Furthermore, the present application makes it possible to accomplish the object described above by a sixth invention, wherein the fixing apparatus comprises a plurality of sheet discharge rotary body pairs, and the upper rotary bodies and the lower rotary bodies are arranged symmetrically or nearly symmetrically with regard to a center of the fixing rotary body and the press rotary body in their rotating axial directions in the first invention through fifth invention according to the present application.
Furthermore, the present application makes it possible to accomplish the object described above by a seventh invention, wherein the upper rotary body is configured to have a form which has smooth outer circumferential surfaces at both ends in its rotating axial direction in the first to sixth inventions according to the present application.
Furthermore, the present application makes it possible to accomplish the object described above by an eighth invention, wherein a surface of the upper rotary body is made mainly of a fluoroplastic material in the first to seventh inventions according to the present application.
Furthermore, the present application makes it possible to accomplish the object described above by a ninth invention, wherein the fixing rotary body is an endless belt of heat-resistant film, the heating body is a ceramic heater including a heating member which is disposed on one surface of a substrate made mainly of a ceramic material to generate heat while receiving an electric power fr
Kanoto Masanobu
Nishigaki Makoto
Sano Atsushi
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Grimley Arthur T.
Ngo Hoang
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