Electrophotography – Having particular structure – Modular or displaceable
Reexamination Certificate
2002-01-22
2003-04-29
Ngo, Hoang (Department: 2852)
Electrophotography
Having particular structure
Modular or displaceable
C399S117000
Reexamination Certificate
active
06556796
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to improvements in apparatus for loading (and unloading) a hollow drum onto (and from) a cantilever-mounted axle adapted to support the drum for rotation. The apparatus of the invention is particularly useful for loading and unloading an image-recording or image-transfer drum in an electrostatographic printer/copier in which minimal clearance is provided between the drum surface and the various processing stations associated with the electrostatographic imaging process.
BACKGROUND OF THE INVENTION
Referring to
FIGS. 1-3
, the above-referenced U.S. application Ser. No. 09/574,425 discloses an electrostatographic document printer
10
that comprises a pair of confronting, cantilever-mounted drums
12
and
16
. Drum
12
typically comprises a hollow metal cylinder having a photoconductive outer layer
14
and serves to record images, in a conventional manner, via the well-known electrostatographic process. Briefly, as drum
12
rotates counter-clockwise, layer
14
is uniformly charged at a primary charging station
20
, imagewise exposed with actinic radiation at an exposure station
22
to produce a charge image on layer
14
, and subjected to toner particles that selectively adhere to the charge image to render such image visible. Continued rotation of drum
12
results in the intermediate transfer of the previously formed toner image to a non-stick outer surface
18
of drum
16
. Thereafter, the image-recording surface of drum
12
is cleansed at cleaning stations
25
and
26
, readying the drum for subsequent image recording. Meanwhile, the toner image on drum
14
is transferred to an image-receiver sheet (not shown), and the drum surface
18
is cleaned at a cleaning station
28
. As will be appreciated, all of the aforementioned processing stations are precisely positioned in close proximity to the outer surfaces of the drums
12
and
16
, and great care must be taken in removing the drums for servicing lest the drum surfaces be damaged by the hardware of the processing stations.
In the printer described above, drums
12
and
16
are rotatably supported by a pair of axles A
2
and A
3
, respectively, that extend outwardly, in a cantilever fashion, from the rear mech plate RP of the printer support frame. Referring to
FIG. 2
, a solenoid-operated drum-support mechanism
32
serves to provide support for the free ends of axles A
2
and A
3
during drum rotation. Such support mechanism is movably mounted on a pivot mount
50
for movement between an operable position in which it supports both drum axles A
1
and A
3
, and a stand-by position (shown in
FIG. 2
) in which it is sufficiently spaced from the drums to enable axial movement of the drums for removal and servicing. In use, the image-recording drum
12
is supported at its opposite ends
12
A and
12
B by a pair of gudgeons
40
and
42
that are releasably press fit into the respective ends of the drum. The rear gudgeon
40
is rotatably mounted directly on axle A
2
, whereas the front gudgeon
42
is rotatably mounted on a stub axle assembly A
1
that, in use, is releasably connected to the free end of axle A
2
. When so connected, beveled edges on each gudgeon cooperate with beveled edges at each drum end to center the drum on the longitudinal axis of axle A
2
. As disclosed in the aforementioned application, when axle assembly A
1
is disconnected from axle A
2
, drum
12
will slide off its supporting gudgeons and will be free to move axially, through an opening in the printer's front mech plate FP for servicing.
As best shown in
FIG. 3
, careful axial movement of drum
12
from the printer frame is facilitated by a drum-loading/unloading structure
100
that is supported by axle A
2
within the drum interior. The drum loading/unloading structure comprises a pair of discs
102
,
103
and a plurality of interconnecting rods
104
. Discs
102
,
103
are provided with concentrically arranged central apertures
102
A,
103
A, each being adapted to receive and slide upon axle A
2
. Rods
104
are mutually parallel with each other and with the longitudinal axis of axle A
2
. The most radially outward surface of each rod extends slightly outside the perimeter of each of the supporting discs and lies on a circle having a diameter slightly less than the inside diameter of drum
12
. The respective lengths of the rods, including their extensions
104
A that extend beyond disc
103
, are slightly less than the length of drum
12
. Thus, upon removing gudgeon
42
from the end
12
B of the drum
12
, it will be appreciated that the drum will slide off the beveled edge of gudgeon
40
and thereby be collectively supported by several of the underlying rods
104
of the drum-loading/unloading structure. To remove the drum from axle A
2
, the operator grasps handles
106
mounted on disc
103
and exerts an axially outward force.
While the drum-loading/unloading apparatus described above is useful in reducing any damage to the drum surface as the drum is removed from the printer frame, it is problematic in certain respects. For example, it will be appreciated that axial movement of the drum will be supported by axle A
2
only so long as the central aperture
103
A of disc
103
maintains contact with the axle A
2
. Once contact is lost as the drum continues to move axially outward, it is up to the operator to assure that the drum axis remains substantially co-linear with the axis of axle A
2
; otherwise, the relatively delicate outer surface of the drum may physically contact the hardware of the various processing stations of the printer and cause damage. Ideally, the drum should be mechanically supported until the drum clears all potentially harmful surfaces as it moves axially from the printer frame. A further problem associated with the drum loading/unloading apparatus of the type described is that, being incapable of providing support for the drum at all times during of its axial movement, relatively slight defects in the drum surface cannot be addressed without totally removing the drum from the printer frame.
SUMMARY OF THE INVENTION
In view of the foregoing discussion, an object of the present invention is to provide an improved drum-loading/unloading apparatus of the type described, one that is substantially more robust than the prior art apparatus, and one that overcomes the aforementioned problems of the prior art apparatus.
According to the invention, an improved apparatus is provided for facilitating the loading and unloading of a hollow cylindrical drum, for example, an image-recording drum in an electrostatographic printer or the like, onto a drum axle having a free end extending outwardly in a cantilever manner from a support frame and having a longitudinally-extending axis about which the drum is adapted to rotate. According to a preferred embodiment, the apparatus of the invention comprises a plurality of telescoping slider mechanisms disposed at equal distances from each other and from the axis of the drum axle. Each of the slider mechanisms comprises a pair of elongated slide members extending substantially parallel to the drum axle. One of the slide members of each pair is rigidly supported by the drum axle, and the other slide member of each pair is slidably mounted on the rigidly supported slide member for movement parallel to the drum axle axis. The slidably mounted slide members of each pair cooperate to support the drum from within for axial movement between a drum-loading position axially spaced from the drum axle, and a loaded position atop the drum axle. Preferably, a total of three slider mechanisms are used to slidably support the drum, and each the slide mechanisms comprises a common drawer slider mechanism of the type commonly used to support a drawer in a cabinet for movement between a closed and open position. Preferably, a latching mechanism is provided to selectively latch the slidably mounted slide members in their respective drum-loading positions to facilitate loading of a drum onto the slide members.
The drum-loading/unl
Chavez Jorge Luis
Greiner Adolf Phillip
Williams Ralph Edward
NexPress Solutions LLC
Ngo Hoang
LandOfFree
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