Information
-
Patent Grant
-
6580888
-
Patent Number
6,580,888
-
Date Filed
Thursday, May 17, 200123 years ago
-
Date Issued
Tuesday, June 17, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 399 119
- 399 110
- 399 116
- 399 126
- 399 117
-
International Classifications
-
Abstract
A developer reference system for a contact development process having machine frame mounted support rollers for the developer roll. Skew between the PC drum and the developer roll is reduced by referencing each to the same support structure. Rolling resistance of the developer roll support rollers is reduced by using thin diameter metal pins for mounting the support rollers.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a contact development system in an electrophotographic imaging apparatus, and, more particularly, to a structure and method for referencing a developer roll to the photoconductive drum in a contact development system.
2. Description of the Related Art
In an electrophotographic imaging apparatus, such as a printer or copier, a photosensitive member, such as a photoconductive drum or belt, is uniformly charged over the surface thereof. An electrostatic latent image is formed by selectively exposing the uniformly charged surface of the photosensitive member. Microscopic marking particles, known as toner, are applied to the electrostatic latent image, and subsequently transferred to the media intended to receive the final, permanent image, which may be paper, an envelope, a transparency or the like. The toner image is fixed to the media by the application of heat and pressure in a fuser.
The application of toner to the electrostatic image on the photosensitive member is commonly referred to as developing or development, and the apparatus for applying the toner to the photoconductive drum or other photosensitive member is commonly referred to as a developing or development unit. The developing unit includes a housing having a compartment therein for containing toner, and a developer roll rotatably supported within the housing. A uniform layer of toner is applied to the developer roll by a supply roll or the like. In what is referred to as a contact development method, the developer roll is rotatably disposed in contact with the photosensitive member, and the developer roll applies a layer of toner directly to the surface of the photoconductive member.
In a contact development system, it is important to keep a constant nip force between the developer roll and the photoconductive drum over the entire length of the developer roll. Constant nip force ensures a uniform application of toner to the surface of the photoconductive drum. If the developer roll is not parallel to the photoconductive drum, the nip force along the developer roll varies, and the toner delivered to the photoconductive drum will not be uniform. Non-uniform application of toner to the photoconductive drum ultimately results in print quality defects.
It is known to support opposite ends of the developer roll on separate rollers mounted in the developer cartridge. The developer roll is spring biased against the photoconductive drum, even though the developer roll can float relative to the photoconductive drum surface. Referencing systems of this type can result in skew between the photoconductive drum and developer roll. Further, as the developer roll rides against the support rollers, the support rollers should rotate freely. However, friction can inhibit support roller rotation, causing uneven wear on the outer surface thereof. This is particularly problematic when, as commonly provided, the support rollers and/or pins mounting the support rollers are made of plastic or the like. Plastic components may deflect, causing skew. Plastic pins mounting the support rollers in the housing are often large in diameter, increasing rolling friction. Skew between the developer roll and the photoconductive drum, and friction in the support rollers are two major contributors to non-uniform nip forces between the developer roll and photoconductive drum. Occurrence of either can result in print quality defects.
The developer cartridge is a replaceable unit, having a life expectancy shorter than that of the base machine in which it operates. When properly operated, the support rollers do not wear excessively, and may not require replacement during the entire anticipated lifespan of the base machine. Therefore, providing the support rollers as part of the developer cartridge is wasteful, resulting in the unnecessary replacement thereof when the developer cartridge is replaced. Thus, needless expense is incurred.
What is needed is a referencing apparatus for a contact development system which minimizes or eliminates skew between the developer roll and photoconductive drum and which reduces friction in the rotation of developer roll support rollers.
SUMMARY OF THE INVENTION
The present invention provides a supporting, or reference structure for a contact development system, that references the developer roll to the same structure as the photoconductive drum, thereby eliminating a variable in the reference structure.
The invention comprises, in one form thereof, a photo imaging apparatus comprising a machine frame including a photoconductive member support assembly and a photoconductive member mounted in said photoconductive member support assembly. A developer cartridge includes a developer roll for applying toner to the photoconductive member. A developer cartridge support assembly includes a reference component mounted on the photoconductive member support assembly and a support component supporting the developer cartridge on the reference surface.
The invention comprises, in another form thereof a contact development system for applying toner to a photoconductive drum in an electrophotographic imaging machine, comprising a photoconductive drum support assembly and a developer cartridge including a housing and a developer roll rotatably mounted in the housing. A reference surface is provided in the photoconductive drum support assembly; and a developer cartridge support extends between the cartridge and the reference surface.
The invention comprises, in still another form thereof, a developer roll referencing apparatus for a contact developing system in an electrophotographic imaging machine having a machine frame and a photoconductive drum mounted in said machine frame. The development system includes a developer cartridge having a housing and a developer roll. The referencing apparatus comprises a reference surface in the machine frame, and a support body for the cartridge, the support body disposed on the reference surface.
The invention comprises, in a further form thereof, a method for referencing a developer roll to a photoconductive drum in a contact development system of an electrophotographic imaging machine. The method comprises providing a photoconductive drum support structure and a reference surface in the structure; providing a developer roll for rotation in contact with the photoconductive drum; urging the roll against the photoconductive drum; and supporting the roll by sliding engagement with the reference surface.
An advantage of the present invention is providing a common mounting component for the photoconductive drum and developer roll support rollers, which substantially reduces the potential for skew between the photoconductive drum and the developer roll, compared to mounting structures known heretofore.
Another advantage is providing a more stable mounting component for the developer roll support rollers.
Yet another advantage is eliminating the unnecessary replacement of developer roll support rollers by placing the support rollers in permanent structural frame components rather than in replaceable unit housings.
BRIEF DESCRIPTION OF THE DRAWINGS
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:
FIG. 1
is a perspective view of a color printer, having some parts removed, and having a contact development system according to the present invention;
FIG. 2
is an enlarged view of a portion of the printer shown in
FIG. 1
; and
FIG. 3
is an enlarged partial, view similar to
FIG. 1
, but having additional components of the printer removed for added clarity; and
FIG. 4
is an enlarged view similar to
FIG. 2
, but having components of the printer removed for added clarity.
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings, and particularly to
FIG. 1
, there is shown a photo imaging apparatus
10
, which is an electrophotographic printer or the like. Photo imaging apparatus
10
is a color printer, and includes four printing stations
12
,
14
,
16
and
18
for printing magenta, yellow, cyan and black images. Each printing station
12
,
14
,
16
and
18
includes a photoconductive member such as PC drums
20
,
22
,
24
and
26
, respectively. PC drums
20
,
22
,
24
and
26
are secured to a machine frame assembly
28
, which includes a front v-bar
30
and a back v-bar
32
. Each printing stations
12
,
14
,
16
and
18
includes a developer cartridge, one such developer cartridge
34
being shown for printing station
12
. It should be understood that each printing station includes a similar developer cartridge
34
; however, only one such developer cartridge
34
is shown for simplicity and clarity in description. The manner in which developer cartridge
34
is associated with printing station
12
, and specifically PC drum
20
of printing station
12
, is similar to the manner in which other such developer cartridges are associated with printing stations
14
,
16
,
18
and PC drums
22
,
24
and
26
, respectively.
A photoconductive member or PC drum support assembly
36
for each PC drum
20
,
22
,
24
and
26
includes front v-bar
30
and back v-bar
32
, which are primary support components, and are rigid and strong. Front v-bar
30
includes a plurality of precisely located notches
50
,
52
,
54
and
56
. Back v-bar
32
includes a similar plurality of notches
58
,
60
,
62
and
64
. Front v-bar
30
and back v-bar
32
are accurately positioned and securely fastened members of frame assembly
28
, and define end support rails for PC drums
20
,
22
,
24
and
26
. PC drum
20
includes end rings
66
and
68
positioned in notches
50
and
58
, respectively. PC drum
22
includes end rings
70
and
72
positioned in notches
52
and
60
, respectively. PC drum
24
includes end rings
74
and
76
positioned in notches
54
and
62
, respectively. PC drum
26
includes end rings
78
and
80
positioned in notches
56
and
64
, respectively.
The construction of the PC drums
20
,
22
,
24
and
26
, the manner in which PC drums are positioned and retained by front and back v-bars
30
and
32
, respectively, and the like are well known to those skilled in the art and will not be described in further detail herein, except as relates specifically to the present invention. Similarly, printing stations
12
,
14
,
16
and
18
include numerous additional components, known to those skilled in the art, and required for creating the electrostatic image and attaching the toner particles thereto. However, such are not shown in the drawings, again for simplicity and clarity in description, and will not be described in further detail herein.
Printing stations
12
,
14
,
16
and
18
of apparatus
10
include contact development systems of developer cartridge
34
. Each developer cartridge
34
is similar, and only a single developer cartridge
34
is described in detail herein.
Developer cartridge
34
includes a housing
90
defining a toner compartment
92
from which toner is deposited on the electrostatic image created on PC drum
20
. A plurality of rolls and the like are provided for metering toner from toner compartment
92
, to provide a consistent deposit thereof on a developer roll
94
. For an even deposit of toner on the surface of PC drum
20
, developer roll
94
must be held in precise parallel relationship with PC drum
20
, and maintain contact therewith essentially along the entire length of the nip between developer roll
94
and PC drum
20
.
In accordance with the present invention, a developer cartridge support assembly
96
for each developer cartridge
34
, also includes front v-bar
30
and back v-bar
32
. Front v-bar
30
includes a plurality of front support rollers
100
,
102
,
104
and
106
rotatably mounted therein. Similarly, back v-bar
32
includes a plurality of back support rollers
110
,
112
,
114
and
116
(
FIG. 3
) rotatably mounted therein. Thus, each printing station
12
,
14
,
16
and
18
includes a front support roll
100
,
102
,
104
or
106
in front v-bar
30
, respectively, and a back support roller
110
,
112
,
114
and
116
in back v-bar
32
, respectively.
In a preferred structure, front support rollers
100
,
102
,
104
and
106
are mounted to front v-bar
30
by metal pins
120
,
122
,
124
and
126
, respectively. Similarly, back support rollers
110
,
112
,
114
and
116
are rotatably mounted to back v-bar
32
by metal pins
130
,
132
,
134
and
136
, respectively. While the present invention contemplates the use of material other than metal for pins
120
,
122
,
124
,
126
,
130
,
132
,
134
and
136
, steel is believed to be a preferred material for its strength and low rolling resistance. Plating pins
120
,
122
,
124
,
126
,
130
,
132
,
134
and
136
with nickel further reduces the rolling resistance. The use of steel for pins
120
,
122
,
124
,
126
,
130
,
132
,
134
and
136
, which are thereafter mounted in rigid front v-bar
30
and back v-bar
32
allows for more rigid attachment than previously used plastic components mounted in developer cartridge
34
. Steel pins can also be of smaller diameter, thereby increasing the wheel-to-axle ratio.
To maintain the desired, precise location of developer roll
94
to PC drum
20
, developer cartridge support assembly
96
further includes a reference surface
140
provided on front support roller
100
. Similar reference surfaces
142
,
144
and
146
are provided on front support rollers
102
,
104
and
106
, respectively. Similar reference surfaces
150
,
152
,
154
and
156
are provided for back support rollers
110
,
112
,
114
and
116
, respectively. As an additional component of developer cartridge support assembly
96
, developer cartridge
34
includes a support component in the way of a front beam
160
extending between reference surfaces
140
and
150
of support rollers
100
and
110
, respectively, for supporting developer cartridge
34
on reference surfaces
140
and
150
of support rollers
100
and
110
, respectively. Instead of a front beam
160
extending from front v-bar
30
to back v-bar
32
, developer cartridge
34
can include individual feet for engaging surfaces
140
and
150
of support rollers
100
and
110
.
Developer cartridges (not shown) for printing stations
14
,
16
and
18
include front beams similar to front beam
160
of developer cartridge
34
. Each developer cartridge
34
and the three remaining developer cartridges (not shown) are thus supported on front support rollers
100
,
102
,
104
and
106
as well as back support rollers
110
,
112
,
114
and
116
. The location of support rollers
100
,
102
,
104
,
106
,
110
,
112
,
114
and
116
relative to PC drums
20
,
22
,
24
and
26
can be precisely controlled during the manufacture of front v-bar
30
and back v-bar
32
by precise control of the relative positions of notches
50
,
52
,
54
and
56
in front v-bar
30
and notches
58
,
60
,
62
and
64
in back v-bar
32
together with the careful location of holes for pins
120
-
126
and
130
-
136
. Then, through careful control during manufacture of the developer cartridges and specifically the position of front beam
160
, the relative position of each PC drum
20
,
22
,
24
and
26
to its respective developer roll such as developer roll
94
is controlled so that the desired nip pressure can be maintained and a parallel relationship secured.
While support rollers
100
through
106
and
110
through
116
are rotatably mounted in front v-bar
30
and back v-bar
32
, respectively, the need is only to allow relative rotation through a limited range. It is not required nor does it occur that support rollers
100
through
106
and
110
through
116
roll on the associated pin
120
through
126
or
130
through
136
with any regularity. Thus, there is little or no wear on reference surfaces
140
through
146
or
150
through
156
. It can be expected that the usable life of support rollers
100
through
106
and
110
through
116
will equal the expected usable life of apparatus
10
, without the need for changing. In previous structures in which support rollers for a developer roll are provided in the developer cartridge, being integral with the developer cartridge, if a developer cartridge is replaced, support rollers were also replaced, often times, needlessly. In accordance with the present invention, with support rollers
100
through
106
and
110
through
116
securely mounted in front v-bar
30
and back v-bar
32
, support rollers
100
through
106
and
110
through
116
can remain in the machine, securely mounted to frame assembly
28
even while developer cartridge
34
and/or other similar developer cartridges not shown for printing stations
114
,
116
and
118
are replaced. The present invention eliminates needless replacement of parts and reduces the expense associated with the manufacture and supply of replacement developer cartridges
34
.
Developer cartridge
34
, and other similar developer cartridges not shown, includes upper support rollers such as upper support roller
162
shown for printing station
12
. The support rollers on v-bars
30
and
32
for each cartridge determine the amount of skew that the developer roll will have with respect to the PC drum. The function of upper support roller
162
, and other similar rear support rollers not shown, is to establish the rotational position of the cartridge developer housing about developer roll
94
. Since the angular position of the cartridge developer housing
90
is not critical to function of the contact development process, it is permissible that this roller be located on a frame member remote to the v-bar assemblies.
In the use of the present invention, the locations of PC drum
20
and developer roll
94
are both referenced to the same structure, front v-bar
30
and back v-bar
32
. Support rollers
100
and
110
are rigidly mounted to front v-bar
30
and back v-bar
32
, respectively. Since the position of developer roll
94
is determined by front beam
160
resting on support rollers
100
and
110
, developer roll
94
is referenced to the same structure as PC drum
20
. The possibility of skew occurring between PC drum
20
and developer roll
94
is minimized, and the nip force between PC drum
20
and developer roll
94
is held constant throughout the length of the nip. Further, the support of developer roll
94
is more robust, with metal pins
120
and
130
mounted in front v-bar
30
and back v-bar
32
, respectively. Friction from rotation of support rollers
100
and
110
is reduced, thereby minimizing yet another source of potential skew between PC drum
20
and developer roll
94
. Waste is reduced by moving minimal wear components from replaceable units having shorter life expectancies, to the base machine that has a longer life expectancy. When developer cartridge
34
is removed, to be replaced by a new cartridge, support rollers
100
and
110
remain in the machine, and needless replacement is eliminated. A new cartridge and developer roll installed in the machine will again be similarly referenced to PC drum
20
.
While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
Claims
- 1. A photo imaging apparatus comprising;a machine frame assembly including a photoconductive member support assembly; a photoconductive member mounted in said photoconductive member support assembly, said photoconductive member being a drum and said photoconductive member support assembly including a front V-bar and a back V-bar having notches therein for supporting said drum; a developer cartridge including a developer roll mounted for rotation in said cartridge for applying toner to said photoconductive member; and a developer cartridge support assembly including a reference surface mounted on said photoconductive member support assembly and a support component connected to said developer cartridge and supporting said developer cartridge on said reference surface.
- 2. A photo imaging apparatus comprising;a machine frame assembly including a photoconductive member support assembly having a front V-bar and a back V-bar with notches therein; a photoconductive drum mounted in said photoconductive member support assembly and supported in said notches; a developer cartridge including a developer roll for applying toner to said photoconductive drum; and a developer cartridge support assembly including a reference surface mounted on said photoconductive member support assembly and a support component connected to said developer cartridge and supporting said developer cartridge on said reference surface; and said developer cartridge support assembly reference surface including support rollers mounted on said front V-bar and said back V-bar.
- 3. The photo imaging apparatus of claim 2, said support rollers mounted in said front V-bar and said back V-bar on metal axial support pins.
- 4. The photo imaging apparatus of claim 2, said support rollers mounted in said front V-bar and said back V-bar on nickel coated steel support pins.
- 5. The photo imaging apparatus of claim 2, said developer cartridge support assembly including a beam supporting said cartridge on said support rollers.
- 6. The photo imaging apparatus of claim 5, said support rollers mounted in said front V-bar and said back V-bar on axial support pins.
- 7. The photo imaging apparatus of claim 6, said pins being metal.
- 8. A contact development system for applying toner to a photoconductive drum in an electrophotographic imaging machine, comprising:a photoconductive drum support assembly, said photoconductive drum support assembly including a front V-bar and a back V-bar; a developer cartridge including a housing and a developer roll rotatably mounted in said housing; a reference surface in said photoconductive drum support assembly; and a developer cartridge support connected to said developer cartridge and extending between said cartridge and said reference surface.
- 9. A contact development system for applying toner to a photoconductive drum in an electrophotographic imaging machine, comprising:a photoconductive drum support assembly including a front V-bar and a back V-bar; a developer cartridge including a housing and a developer roll rotatably mounted in said housing; a reference surface in said photoconductive drum support assembly; and a developer cartridge support connected to said developer cartridge and extending between said cartridge and said reference surface, said photoconductive drum support assembly including a front V-bar and a back V-bar; and said reference surface including developer roll support rollers mounted on said front V-bar and said back V-bar.
- 10. The contact development system of claim 9, including metal pins securing said support rollers to said front and back v-bars.
- 11. The contact development system of clam 9, said developer cartridge support including at least one leg connected to said housing and supported on said rollers.
- 12. The contact development system of claim 11, including pins in said front and back v-bars, and said rollers mounted on said pins.
- 13. The contact development system of claim 12, said pins being metal.
- 14. The contact development system of claim 12, said pins being nickel coated steel.
- 15. A developer roll referencing apparatus for a contact developing system in an electrophotographic imaging machine having a machine frame including a PC drum support assembly and a photoconductive drum mounted in said PC drum support assembly, said development system including a developer cartridge having a housing and a developer roll, said referencing apparatus comprising:a reference surface in said PC drum support assembly; and a support component for said cartridge, said support component being connected to the developer cartridge and disposed on said reference surface; and said reference surface including support roller.
- 16. The referencing apparatus of claim 15, said support roller rotatably mounted on a pin.
- 17. The referencing apparatus of claim 16, said pin being metal.
- 18. The referencing apparatus of claim 16, said pin being nickel coated steel.
- 19. A developer roll referencing apparatus for a contact development system in an electrophotographic imaging machine having a machine frame including a PC drum support assembly and a photoconductive drum mourned in said PC drum support assembly, said development system including a developer cartridge having a housing and a developer roll rotatably mounted in the housing, said referencing apparatus comprising:a reference surface in said PC drum support assembly; a support component for said cartridge, said support component being connected to the developer cartridge and disposed on said reference surface, and; said machine frame including a front V-bar and a back V-bar, said photoconductive drum mounted in notches in said front V-bar and said back V-bar, and said reference surface including support rollers mounted on said front V-bar and said back V-bar.
- 20. The referencing apparatus of claim 19, said support component including a beam extending between said support rollers.
US Referenced Citations (21)