Information
-
Patent Grant
-
6816692
-
Patent Number
6,816,692
-
Date Filed
Wednesday, May 21, 200321 years ago
-
Date Issued
Tuesday, November 9, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 399 222
- 399 119
- 399 120
- 399 279
- 399 313
- 399 328
- 399 110
-
International Classifications
-
Abstract
Gear (52) and resin body (2) supported on shaft (1) and between frame members (14a) and (14b) are protected from contacting a frame member. Frame (14a) has a partial hole (22) with an opening (24) and a cavity (26), which is open at the hole (22) and on the side toward the opening (24). A bearing (18) has a inner body (30) which internally is partially circular with diameter substantially the same as opening (22). The outer portion of body (30) forms an outwardly extending nub (34). Wall (36) extends across body (30). The part (38) of bearing 18 opposite body 30 has an extended part (38a) to serve as an electrical contact. A shaft end (Sa) past a circular ledge (3a) is supported by bearing (18). The nub (34) fits in the cavity (26) and the wall (36) defines the proper position of rotation of the bearing. This protects gear (52) from being dislodged from its position on shaft (1). Where the resin body (2) is for electrophotographic developing, toner carried by the body (2) is not subject to effects from the body contacting a frame element or the like.
Description
TECHNICAL FIELD
This invention relates to mounting rollers, such as electrophotographic developer rollers, to be protected from being damaged or deformed by lateral forces. Such forces may come from drive forces employing helical gears or from external impact such a being dropped.
BACKGROUND OF THE INVENTION
Rollers such as electrophotographic developer rollers are relatively pliable cylindrical masses mounted on a steel shaft. (The cylindrical mass will be termed here the “roller body.”) The steel shaft is inherently resistant to deformation. Deformation of the roller body by lateral forces can cause the support frame to impact gears mounted on the shaft, which can destroy the gear operation. Additionally, deformation of the roller body by lateral forces results in uneven development and escape of toner out of the electrostatic device, both events being unacceptable.
Prior rollers are known which provide a circular ledge in the support shaft on each side of the support shaft. The roller body is located between the ledges. The ledges, as well as edges of the roller body contact the frame. This can be acceptable where the gear on the shaft is press fit and can be moved slightly when dropped, and where toner escape is prevented by the frame being sufficiently stiff.
A prior assembly for preventing lateral forces on the roller body is understood to provide a notch for a C clip spaced a short distance from the ledge at each ledge. The notches are positioned immediately past the frame holding the roller, so that the C clip in each notch prevents significant lateral movement by abutting the frame. (The frame at this location normally includes a bearing in which the shaft is inserted.) The shaft is held in one lateral direction by one of the C clips abutting the frame and the shaft is held in the other lateral direction by the other C clip abutting the frame.
Such an assembly, however, does not protect a gear mounted on the shaft when the frame deflects so much that a C clip is displaced. Similarly, such an assembly does not protect the roller body when the frame deflects so much that the roller body comes in contact with the frame or another element on the side of the assembly. Moreover, it is desirable to eliminate the C clips, as they are separate elements having some cost and some potential of failure and are difficult to repair.
DISCLOSURE OF THE INVENTION
In accordance with an implementation of this invention a ledge is provided on each side of the roller shaft. On one end of the shaft the ledge abuts the frame element to protect the roller body from lateral movement in one direction in the manner of the ledge in of the foregoing prior assembly. A unique, first bearing and frame combination is provided to receive the shaft on the other end of the shaft. The first bearing has a small width and a larger width, the larger width having an extended part. The frame has an opening to allow the bearing to enter when the small width faces the opening and has a cavity to receive a part of the larger width when the bearing is rotated. The cavity has an outer wall that is part of the frame.
The first bearing has a central hole in which the shaft is inserted. The opposite end of the shaft is inserted into a conventional, second bearing in the frame on the side opposite to the first bearing. The second bearing may be conventional when it is in a stiff element such as a gear plate. With the shaft inserted, the first bearing is rotated so that its small width fits into the frame opening and is then inserted into that frame opening. Then the first bearing is rotated so that the extended part is in the cavity of the frame.
In this assembly both sides of the shaft abut the bearings, which are part of the frame. Therefore, the roller body is prevented from coming in contact with the frame.
In an embodiment, the shaft carries a helical gear, which is positively attached to the shaft, specifically by a snap fit on the gear that mates with a notch fitted into a ledge in the shaft. This positions the gear against movement by lateral forces caused by the helical gear design, which permits the gear assembly to be compact and carry large forces. The gear is prevented from being stripped out of the notch when the cartridge is subjected to large lateral forces by the shaft being firmly positioned with respect to the frame.
The first bearing preferably is electrically conductive and has an extended part on its outside past the frame for contact with an electrical contact pad in a cartridge in which the roller is mounted.
BRIEF DESCRIPTION OF THE DRAWINGS
The details of this application will be described in connection with the accompanying drawings, in which:
FIG. 1
is the central support shaft having circular ledges on each end;
FIG. 2
is the mounting assembly of this invention in an electrostatic developer cartridge, with the roller body not shown so as to better illustrate of this invention.
FIG. 3
is the unique frame configuration of this invention;
FIG. 4
is a perspective view of the bearing of this invention from the inside of the developer cartridge when installed;
FIG. 5
is a perspective view of the bearing of this invention from the outside of the developer cartridge when installed
FIG. 6
shows the bearing installed from the inside of the developer cartridge;
FIG. 7
shows the bearing installed from the outside of the developer cartridge and shows the roller body; and
FIG. 8
illustrates the gear assembly, having a gear mounted on the shaft of the roller.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1
shows the steel shaft
1
, which supports a roller body
2
(
FIG. 7
) disposed around shaft
1
to form a developer roller. Roller body
2
is a resilient, polymeric material for which it is an aspect of this invention that roller body
2
is protected from lateral forces.
Shaft
1
has circular ledges
3
a
,
3
b
near each end of shaft
1
formed by the shaft being reduced to cylindrical end sections
5
a
,
5
b
. End section
5
b
has a flat end section
5
bb
to mesh with a gear
52
(FIG.
8
). Shaft
1
differs from that of the prior assembly discussed in the foregoing essentially by having no notch for a C clip and by having a notch
1
a
for engagement with a drive gear snap.
FIG. 2
shows the shaft alone installed in a toner cartridge
10
. (The full developer roller with shaft
1
and roller body
2
is shown in FIG.
7
). The cartridge
10
carries a supply of electrostatic toner powder that is supplied to the roller body
2
for application to a photoconductor drum (not shown). The opening
12
on the upper right is to support a bearing for a toner paddle. Such a system may be entirely conventional and therefore will not be discussed in detail.
Of direct interest with respect to this invention are the structural support elements of cartridge
10
, including left wall
14
a
and right wall
14
b
, collectively known as the frame. Shaft is supported for rotation by right bearing
16
, which is a round and cylindrical, and by left bearing
18
, which is unique in accordance with this invention. Bearings
16
and
18
are held by side walls
14
b
and
14
a
respectively and therefore constitute part of the frame of cartridge
10
. As is conventional, bearing
18
is a hard, smooth durable plastic, which provides a low-friction surface for shaft end
5
a
to be reliably positioned for rotation. Bearing
18
is a POM (polyoxymethylene) plastic carbon filled to be electrically conductive so as to provide an electrical potential to shaft
1
during use.
FIG. 3
illustrates the left wall
14
a
and surrounding areas without the bearing
18
. Hole
20
is to receive a bearing to support a standard toner adder roller, which will not be discussed in further detail. Of direct interest is opening
22
in wall
14
a
having a circular perimeter except for a gap
24
, and adjoining a cavity
26
. Cavity
26
has a bottom and back surface extending into cartridge
10
, but is open on where it faces hole
22
and on the front side. Cavity
26
has an outer wall
14
aa
on the side toward hole
22
.
FIG. 4
shows bearing
18
from the side facing the interior of cartridge
10
when bearing
18
is installed on cartridge
10
. Bearing
18
has two flat sides extending across an inner body
30
defining a narrow dimension
32
. Remaining internal portions of inner body
30
define a circular perimeter. Dimension
32
is substantially the same size (equal to or somewhat less in size) to the width of opening
24
in hole
22
(FIG.
3
). The circular perimeter of inner body
30
is substantially equal in diameter to or slightly greater than the diameter of the central portion of hole
22
.
An outer portion of inner body
30
is an outwardly extending nub
34
that conforms in size and outer contour to cavity
26
(FIG.
3
). Nub
34
is located generally between the flat sides of inner body
30
. Bearing
18
has a wall
36
extending across inner body
30
.
The outer body
38
of bearing
19
is generally circular, but has an extended part
38
a
(
FIG. 5
) to facilitate contact to an electrical contact pad
39
(FIG.
7
). Finally, bearing
18
has a central hole
40
to receive shaft end
5
a
. Hole
40
is substantially equal in size to shaft end
5
a
Hole
40
has narrow channels
42
to collect wear debris and contamination from toner and paper dust, as is conventional. FIG.
5
and
FIG. 7
show bearing
18
viewed toward the side outside of cartridge
10
when installed. Extended part
38
a
presses against electrical contact pad
39
and thereby forms an electrical connection between pad and shaft.
1
To install bearing
18
, the end
5
a
of shaft
1
is first inserted in hole
40
. Bearing
18
is then turned until the flat dimension
32
of bearing
18
faces gap
24
with the nub
34
is positioned away from hole
22
. Since dimension
32
fits within gap
24
, bearing
18
can be moved into hole
22
. When that is done, bearing
18
is then rotated to bring nub
34
into cavity
26
(counterclockwise as viewed from the
FIG. 3
perspective). Wall
36
contacts the lower edge of hole
22
to define when the rotation is complete, which is when nub
34
occupies substantially all of cavity
26
. Bearing
18
installed is shown from the inside of cartridge
10
without roller body
2
in FIG.
2
and is shown from the outside with the entire roller of shaft
1
and roller body
2
in FIG.
7
.
The side of cartridge
10
having bearing
16
carries the gear mounting plate
52
. Plate
52
is a rigid plastic and firmly mounted to wall
14
b
, as by at least one screw
53
(FIG.
8
). Therefore, plate
52
is much more rigid than opposite wall
14
a
. For that reason bearing
16
in this embodiment is a standard bearing having nothing corresponding to nub
34
fitting in a cavity in the frame. Bearing
16
is a cylindrical structure integral with plate
52
with inner hole that receives shaft end
5
b
surrounded by an outer surface against which ledge
3
b
abuts. Bearing plate
52
, which includes bearing
16
, is 30 percent glass filled Nylon 6/6 with 15 percent polytetrafluoroethylene.
FIG. 8
illustrates gear
52
mounted on shaft
1
where it extends past the frame of cartridge
10
, as well as other gears forming a gear assembly in this embodiment Gear
54
receives a driving from the device (not shown) in which the cartridge
10
is mounted. Such force is transmitted through gear
56
to gear
52
. Gears
52
,
50
and
54
are helical gears. As the gear assembly shown is quite compact and requires a relatively strong drive force on element
54
, gear
52
can not be held by a press fit. Instead, gear
52
is positively attached by a tab member
52
a
integral with gear
52
. Tab member
52
a
presses by its natural resilience into notch
1
a
of shaft
1
(also FIG.
2
). This invention prevents gear
52
from being displaced from the position of
FIG. 8
because no element of the frame of cartridge
10
can contact gear
52
.
Alternatively, bearing
16
may be a separate member having flats to form a narrow dimension as discussed in connection with bearing
18
. and installed through a gap in the manner of bearing
18
. Such a flat dimension and installation through a gap is known. As another alternative, bearing
16
could be a mirror image version of bearing
18
(expect without extension
38
a
as unnecessary), with plate
52
or other frame member having a cavity corresponding to cavity
26
.
In accordance with this invention, forces impacting cartridge
10
rightward as viewed by the drawings will tend to force roller body
2
into wall
14
a
. Instead, however, ledge
3
a
in shaft
1
contacts bearing
18
, which moves as part of the frame. Bearing
18
moves with wall
14
a
by force from nub
34
abutting wall
14
aa
of cavity
26
. Roller body
2
necessarily remains spaced from contact with any frame element or the like. Also, shaft
1
is prevented by wall
14
a
from moving enough to displace gear
52
.
A wide variety of alternative structures can carry out this invention so long as they provide an abutment that requires the bearing to move laterally with lateralmovement of the frame and a ledge on the shaft abutting the bearing.
Claims
- 1. An assembly to support a roller having a roller body and a support shaft comprising:a frame having a partially circular hole having an open side said hole having a first diameter where said hole has opposite sides, said frame having a cavity having a open side facing said hole and an open side facing said open side of said hole and an outer wall contiguous to said hole; a first bearing held in said hole, said first bearing having a partially circular center portion of diameter substantially the same as said first diameter, said first bearing having an outer nub extending past said diameter of said central portion, said nub being positioned in said cavity so as to abut said outer wall contiguous to said hole when moved in the direction of said hole; and a supporting shaft carrying a roller body disposed around said supporting shaft, said supporting shaft having a first end portion held for rotation on said first bearing and a first ledge, said first ledge being located to abut said first bearing, said supporting shaft having a second end portion held for rotation is a second bearing opposite said first end portion and a second ledge, said second ledge being located to abut said second bearing.
- 2. The assembly as in claim 1 in which said first bearing is electrically conductive and has an extended part for contacting an electrical contact member.
- 3. The assembly as in claim 2 in which said first bearing has a wall extending across said center portion of said first bearing to locate said nub in said cavity.
- 4. The assembly as in claim 3 in which said first bearing has sides forming a portion narrower than said first dimension which fits in said opening of said frame to permit insertion of said first bearing in said frame and said nub is located generally between said sides of said portion narrower than said first dimension.
- 5. The assembly as in claim 3 in which said supporting shaft has a part extending past said frame and a gear is mounted to and positively attached to said part extending past said frame.
- 6. The assembly as in claim 2 in which said first bearing has sides forming a portion narrower than said first dimension which fits in said opening of said frame to permit insertion of said first bearing in said frame and said nub is located generally between said sides of said portion narrower than said first dimension.
- 7. The assembly as in claim 2 in which said supporting shaft has a part extending past said frame and a gear is mounted to and positively attached to said part extending past said frame.
- 8. The assembly as in claim 1 in which said first bearing has a wall extending across said center portion of said first bearing to locate said nub in said cavity.
- 9. The assembly as in claim 8 in which said first bearing has sides forming a portion narrower than said first dimension which fits in said opening of said frame to permit insertion of said first bearing in said frame and said nub is located generally between said sides of said portion narrower than said first dimension.
- 10. The assembly as in claim 8 in which said supporting shaft has a part extending past said frame and a gear is mounted to and positively attached to said part extending past said frame.
- 11. The assembly as in claim 1 in which said first bearing has sides forming a portion narrower than said first dimension which fits in said opening of said frame to permit insertion of said first bearing in said frame and said nub is located generally between said sides of said portion narrower than said first dimension.
- 12. The assembly as in claim 11 in which said supporting shaft has a part extending past said frame and a gear is mounted to and positively attached to said part extending past said frame.
- 13. The assembly as in claim 1 in which said supporting shaft has a part extending past said frame and a gear is mounted to and positively attached to said part extending past said frame.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
3667310 |
Hahner |
Jun 1972 |
A |
6530692 |
Wyer |
Mar 2003 |
B2 |
6654583 |
Suzuki et al. |
Nov 2003 |
B2 |
Foreign Referenced Citations (1)
Number |
Date |
Country |
05134573 |
May 1993 |
JP |