Stock material or miscellaneous articles – Hollow or container type article – Glass – ceramic – or sintered – fused – fired – or calcined metal...
Reexamination Certificate
1999-07-20
2002-04-23
Thibodeau, Paul (Department: 1773)
Stock material or miscellaneous articles
Hollow or container type article
Glass, ceramic, or sintered, fused, fired, or calcined metal...
C428S036200, C428S036800, C428S295400, C428S296100, C428S297100, C428S421000, C428S422000, C428S447000, C428S906000, C428S167000, C399S303000, C399S307000, C399S312000, C399S313000
Reexamination Certificate
active
06376033
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a transfer-fixing belt for an electronic appliance and a method of manufacturing the same, particularly, to a fixing belt for a fixing device used in a electrophotographic machine, particularly, a copying machine, a color printer or a facsimile, for melting a toner and fixing the molten toner to a paper sheet or the like and a method of manufacturing the same.
It was customary to use a transfer roll made of a sponge rubber having a semi-conductivity for transferring a toner from a photosensitive drum onto a paper sheet in an electronic appliance using an electrophotographic system such as a copying machine, a color printer or a facsimile. The transfer roll includes, for example, a semi-conductive sponge roll having a hardness of about 30° (Asker C type), which is prepared by mixing a conductive powder with an ethylene-propylene rubber to control the electrical resistance at 10
8
to 10
9
&OHgr;·cm, as described in “Japan Hardcopy '91, p 27).
FIG. 7
shows the concept of a copying machine (or a color printer). As shown in the drawing, the copying machine includes a photosensitive drum
1
. A transfer roll
2
, a developing roll
3
, and a charging roll
4
for charging the photosensitive drum
1
are arranged in the vicinity of the photosensitive drum
1
. Also, a fixing device
7
consisting of a fixing roll
5
and a pressurizing roll
6
arranged to face the fixing roll
5
is arranged on the downstream side of the photosensitive drum
1
. In the copying machine of the particular construction, a toner image is formed by the developing roll
3
on the photosensitive drum
1
and transferred by the transfer roll
2
onto a paper sheet
8
. Then, the paper sheet
8
bearing the toner image is transferred through a clearance between the fixing roll
5
heated to about 200 to 250° C. and the pressurizing roll
6
. As a result, the toner image is fixed to the paper sheet
8
. At the same time, the toner image is smoothed by the pressure applied to the paper sheet
8
when the paper sheet
8
passes through the clearance between the rolls
5
and
6
.
FIG. 8
shows in a magnified fashion the fixing portion, which is called a roll-nip system, shown in FIG.
7
. As shown in
FIG. 8
, the pressurizing roll
6
comprises a mandrel
9
made of aluminum and a surface layer
10
covering the mandrel
9
. The surface layer
10
consists of a heat-resistant resin adapted for releasing the toner such the heat resistant resin sold under the trademark TEFLON®. On the other hand, the fixing roll
5
comprises a mandrel
12
having a heater
11
housed therein, a lower layer
13
covering the mandrel
12
and formed of a heat-resistant soft silicone rubber (or silicone sponge), and a PFA tube (or FEP tube)
14
covering the lower layer
13
and serving to facilitate release of the toner.
An oil supply roll
15
for coating the fixing roll
5
with a silicone oil is arranged near the fixing roll
5
. The silicone oil coating prevents a toner
16
from being attached to the fixing roll
5
. Further, a cleaning device
17
for removing the residual toner and paper dust remaining on the fixing roll
5
is arranged near the fixing roll
5
.
Several problems must be solved for increasing the copying speed in the roll-nip system described above. It should be noted that a predetermined contact time between the rolls is required for melting the toner and fixing the molten toner to the paper sheet. For ensuring a long contact time, it is conceivable to increase the thickness of the rubber layer or to employ a wide-nip system in which the diameter of the rubber roll is increased so as to increase the nip width (distance of the contact portion between the fixing roll
5
and the pressurizing roll
6
). However, the apparatus is rendered bulky and the heat conduction is lowered by the increased rubber amount, making it substantially impossible to put these techniques to practical use. It is also proposed to use a softer solid silicone rubber so as to bring about bulge during the contact time and, thus, to increase the nip width. However, an appreciable effect cannot be obtained in this case.
Under the circumstances, new proposals are being made for increasing the copying speed by employing a wide-nip technique. Specifically, known is a belt-nip system using the fixing roll
5
and a transfer-fixing belt
18
in combination as shown in FIG.
9
. As shown in the drawing, the transfer-fixing belt
18
is stretched about a pressurizing roll
19
in contact with the fixing roll
5
via the belt
18
, a supporting roll
20
and a driving roll
21
.
Each of Japanese Patent Disclosure (Kokai) No. 61-132972 and Japanese Patent Disclosure No. 5-150679 discloses a wide-nip technique using a fixing device of a belt-nip system in place of the conventional roll-nip system for increasing the nip width with the fixing roll and, thus, increasing the copying speed.
JP '972 noted above proposes a method of forming a belt with a thin film for shortening the warm up time. In this prior art, a heat resistant polyimide resin film is used as a material of the fixing belt and a Teflon® resin or silicone rubber layer adapted for releasing the toner is laminated on the resin film to prepare an endless belt.
On the other hand, JP '679 discloses a fixing roll constructed as shown in FIG.
9
. Specifically, it is taught that an aluminum mandrel having an outer diameter of 46 mm is covered with an intermediate HTV silicone rubber layer having a hardness of 45 Shore A and a thickness of 2 mm. Further, a silicone RTV rubber layer as a top coating layer having a thickness of 50 &mgr;m is formed by a dip coating method on the surface of the intermediate layer to form an elastic rubber layer having a mirror surface. The endless belt transferred between the fixing roll and the pressurizing roll is formed of a polyimide film having, for example, a thickness of 75 &mgr;m, a width of 300 mm and a circumferential length of 288 mm. Since the endless belt is formed of a hard polyimide film, it is considered reasonable to understand that the surface of the fixing roll is covered with the elastic rubber layer so as to impart elasticity to the fixing roll surface that is brought into contact with the toner.
Japanese Patent No. 2650864 proposes a fuser belt (fixing belt) of a three-layer structure as a seamless belt. It is taught that the belt comprises an inner resistance layer, an intermediate polyimide layer and an outer layer adapted for releasing the toner and made of a material having a low surface energy such as biton, Teflon® resin or silicone.
Further, Japanese Patent No. 2657990 proposes a fixing system in which a transfer material and a PET (polyethylene terephthalate) film having a thickness of 6 &mgr;m are bonded to a pressurizing roll. In this prior art, the pressurizing roll is covered with a silicone rubber elastic layer.
The PET film used as a transfer-fixing belt is seriously defective in that the film is greatly shrunk thermally. The melting and fixing of the toner are performed in a fixing device heated to 220 to 250° C. The thermal shrinkage of the PET film at 200° C. reaches 5% in the vertical direction. Since the transfer-fixing belt is used at temperatures around the melting point (230° C.) of PET, irregularities are generated over the entire surface of the transfer-fixing film, resulting in failure to perform a satisfactory fixation. On the other hand, polyimide, which is another main material of the transfer-fixing belt, is free from the defects described above. However, polyimide is highly costly.
The transfer-fixing belt consisting of a plastic film alone is generally low in tear strength, with the result that, where the edge portion of the belt is scratched or cracked, the cracking grows easily to cause the entire belt to be torn. Further, the transfer-fixing belt consisting of a plastic film alone is generally low in flexibility in the thickness direction, resulting in failure to be deformed along the toner image formed as a projecting portion on a
Onuki Akio
Sonobe Saburo
Kinyosha Co., Ltd.
Thibodeau Paul
Volpe and Koenig P.C.
Zacharia Ramsey
LandOfFree
Fixing belt for an electrical appliance and method of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fixing belt for an electrical appliance and method of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fixing belt for an electrical appliance and method of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2898825