Electrophotography – Internal machine environment – Particle or contaminant control
Reexamination Certificate
2001-04-04
2002-06-11
Grainger, Quana M. (Department: 2852)
Electrophotography
Internal machine environment
Particle or contaminant control
C399S105000
Reexamination Certificate
active
06405003
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a seal structure for preventing powder or liquid contents of a casing from leaking from axial end portions of the casing, the casing containing a cylindrical member provided so as to be freely rotatable above and parallel to a bottom surface portion of the casing, and more particularly, to a seal structure that can be employed effectively with a development roller for a developing unit of an electronic photographic type image forming apparatus.
2. Description of the Related Art
A seal structure for preventing toner from leaking from the longer axial ends of a development roller that forms part of a developing unit in an electrophotographic image forming apparatus is disclosed in Japanese Laid-Open Patent Application No. 8-36306.
FIG. 1
is a diagram showing a perspective view of a seal structure
51
provided at a front portion of a bottom part of a toner cartridge or casing
61
that also forms part of the developing unit
60
, with
FIG. 2
showing a frontal view thereof. It should be noted that although
FIGS. 1 and 2
show only the left half of the developing unit
60
, the right half has an identical corresponding structure.
To proceed with a description of the seal structure
51
, the front portion of the bottom part of the toner casing
61
is openly disposed opposite a photosensitive drum not shown in the diagram, with a developing roller
52
provided at the open part. A toner supply roller not shown in the diagram is provided at the back of the developing roller
52
and in contact with the developing roller
52
. The photosensitive drum would be positioned at the front of the developing roller
52
shown in
FIG. 2
, that is, between the observer and the sheet of paper on which the diagram is printed.
In the development process according to the developing unit
60
, the toner inside the toner casing
61
is supplied to the photosensitive drum via the toner supply roller and the developing roller
52
. In this case, a rotation of the developing roller
52
in a direction indicated by the arrow B in
FIGS. 1 and 2
supplies the toner at the bottom portion of the interior of the toner casing
61
to the photosensitive drum, with any toner that did not contribute to the development of the image being scraped from the drum by a recovery blade not shown in the diagram and returned to the interior of the toner casing
61
.
The seal structure
51
described above prevents toner T remaining in the space between the bottom of the developing roller
52
and the floor of the toner casing
62
from leaking into a space
55
on an outer side of an outer edge surface
52
a
of the developing roller
52
.
According to the above-described seal structure
51
, by using an adhesive and adhering a sheet-like seal member
53
to a toner casing floor portion
63
disposed opposite a lower outer edge of the developing roller
52
, the lower outer edge of the developing roller
52
and the corresponding floor portion
63
compressively deform the seal member
53
. In other words, the floor portion
63
becomes an adhesive surface for the seal member
53
. However, in the course of the developing process the outer edge of the developing roller
52
is compressed as it rotates by the seal member
53
, unavoidably generating a certain amount of heat.
In the above-described seal structure
51
, the outer edge of the developing roller
52
is parallel to the casing floor
62
and the seal member
53
is of uniform thickness as it is adhered to the adhesive surface
63
, so the seal function is effected by uniformly compressively deforming the seal member
53
. Such an arrangement poses a number of disadvantages. For example, if the seal pressure is low (that is, if the amount by which the seal member
53
is deformed is small), then the toner T can leak out into the space
55
via the contact between the outer edge of the developing roller
52
and the seal member
53
. Additionally, if the seal pressure is increased to counteract the above-described possibility and to more securely prevent leakage of the toner, then there is the disadvantage of an increase in the amount of frictional heat generated at the point at which the outer edge of the developing roller
52
and the seal member
53
contact each other. In extreme cases, the toner itself is melted by the heat so generated. Although to some extent it is possible to reduce the amount of heat generated by friction by making the surface of the seal member smoother and more slippery so as to reduce friction, there is a limit to what such countermeasures can achieve.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide an improved and useful seal structure in which the above-described disadvantages are eliminated.
A more specific object of the present invention is to provide an improved and useful seal structure in which the contents of the casing (whether in powder or liquid form) are prevented from leaking outside thereof.
Another and more specific object of the present invention is to provide an improved and useful seal structure in which a rise in temperature due to heat caused by friction between the cylindrical member and the seal member can be reduced.
The above-described objects of the present invention are achieved by a seal structure comprising a seal member for preventing toner from leaking out of a casing, the seal member adhesively provided and compressively deformed between an interior floor portion of the casing and a lower outer edge portion of a cylindrical member disposed so as to rotate freely above and parallel to the interior floor of the casing, the seal member being made of an elastic material and disposed so that a degree of compressive deformation of the seal member is greater toward a longitudinal center of the cylindrical body in an axial direction thereof than at the outer edge of the cylindrical body.
According to the above-described aspect of the invention, the sealing function of the seal structure is greatly improved over the conventional art and leakage of the toner from the axial ends of the casing can be securely prevented. Additionally, the amount of heated generated by friction between the seal member and the static parts of the unit is reduced, thus preventing the toner from melting.
The above-described objects of the present invention are also achieved by the seal structure as described above, wherein the seal member is a sheet of uniform thickness and a portion of the interior floor of the casing to which the seal member is adhered is higher toward the longitudinal center of the cylindrical member than toward the edge of the cylindrical member.
According to the above-described aspect of the invention, the seal structure can be produced simply and inexpensively because the seal member can continue to be made of a single strip of uniform thickness while the slant of the adhesive surface allows differential pressure to be applied to different part of the seal member so as to provide a better seal.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.
REFERENCES:
patent: 5794101 (1998-08-01), Watanabe et al.
patent: 5870651 (1999-02-01), Shimada
patent: 6101894 (2000-08-01), Sato et al.
patent: 4-25875 (1992-01-01), None
patent: 4-011556 (1992-01-01), None
patent: 8-036306 (1996-02-01), None
patent: 8-308164 (1996-11-01), None
patent: 9-026743 (1997-01-01), None
patent: 11-184230 (1999-07-01), None
Grainger Quana M.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh & Company, Ltd.
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