U.S. patent number 3,906,896 [Application Number 05/422,053] was granted by the patent office on 1975-09-23 for ink applicator.
This patent grant is currently assigned to Xerox Corporation. Invention is credited to Stanley M. Stansell.
United States Patent |
3,906,896 |
Stansell |
September 23, 1975 |
Ink applicator
Abstract
A reproduction system includes an ink applicator body which is
positioned adjacent to a surface to be inked for transferring ink
from the body to the surface. The applicator body has an array of
lands and depressions or grooves formed on a surface thereof. A
means for supplying ink to the applicator is provided and an
improved doctor means for regulating the ink on the applicator
includes an elongated body of generally circular cross section
which is formed of an elastomeric material and means for mounting
the elastomeric body in contact with a surface of the applicator.
Means provide relative motion between the applicator body and the
doctor body.
Inventors: |
Stansell; Stanley M. (Columbus,
OH) |
Assignee: |
Xerox Corporation (Stamford,
CT)
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Family
ID: |
26909453 |
Appl.
No.: |
05/422,053 |
Filed: |
December 5, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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214873 |
Jan 3, 1972 |
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Current U.S.
Class: |
399/239;
118/261 |
Current CPC
Class: |
G03G
15/102 (20130101) |
Current International
Class: |
G03G
15/10 (20060101); G03G 015/10 () |
Field of
Search: |
;118/262,104,117,118,119,DIG.23,637,261 ;354/318 ;355/10 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McIntosh; John P.
Parent Case Text
This application is a division of Ser. No. 214,873, filed Jan. 3,
1972, now abandoned.
Claims
What is claimed is:
1. In an electrostatographic reproduction system having a means for
establishing a latent electrostatic image on a photoreceptive
surface, a means for developing said latent electrostatic image by
applying a polar ink to the image areas of the surface, said
developing means having an ink applicator body which is positioned
adjacent said photoreceptor surface for transferring ink from said
applicator body to said photoreceptive surface, said applicator
body having an array of lands and depressions formed on a surface
thereof, a means for supplying ink to said applicator, the
improvement for removing ink from said lands and regulating the
level of ink in said depressions comprising;
an elongated body of elastomeric material of generally circular
cross section;
means for supporting the elastomeric material in contact with the
surface of said applicator, said means including a pair of spaced
apart support members, a platform supported by the support members,
a bar having a longitudinally extending groove in which the
elongated body is supported, the bar being slidably seated on the
platform, bias means coupled to the bar for pressing the
elastomeric material into contact with the applicator, said bias
means include a backing bar and a pair of springs, one of the
springs coupling the backing bar to one of the support members and
the other of the springs coupling the backing bar to the other of
the support members, and means for rigidly securing the bar after
the elastomeric material has been pressed against the applicator;
and
means for providing relative motion between said elastomeric
material and said applicator surface.
2. Apparatus as defined in claim 1 wherein each of the support
members includes a slot extending in a direction parallel to the
platform; wherein the backing bar includes a pair of rods, each of
the rods projecting transversely through a different one of the
slots; and wherein said one of the springs is connected to an end
of one of the rods and the other of the springs is connected to an
end of the other of the rods.
3. Apparatus as defined in claim 2 wherein said means for rigidly
securing the bar include a screw and means for supporting the
screw, said means for supporting the screw being located so as to
permit rotation of the screw into abutment with the bar.
4. Apparatus as defined in claim 3 further including at least one
other elongated body; and wherein said bar includes at least one
other longitudinally extending groove, each of said one other
groove accommodating a different one of said at least one other
elongated body.
5. Apparatus as defined in claim 3 wherein said means for
supporting the screw includes a plate connected to each of the
support members.
6. Apparatus as defined in claim 1 wherein said means for rigidly
securing the bar include a screw and means for supporting the
screw, said means being located so as to permit rotation of the
screw into abutment with the bar.
7. Apparatus as defined in claim 1 further including at least one
other elongated body; and wherein said bar includes at least one
other longitudinally extending groove, each of said one other
groove accommodating a different one of said at least one other
elongated body.
Description
This invention relates to ink applicator arrangements. The
invention relates more particularly to an improved means for
applying developer ink to an imaged area in a reproduction
system.
In various reproduction and copying systems, it is desirable to
apply a developer ink to an image or record medium. More
particularly, in one form of electrostatic copying process, a
latent image is established electrostatically on an image retention
surface and is then developed by contacting the surface with a
liquid developing material. The developing material adheres to the
surface and conforms to the image. The image is transferred to a
record medium for recording, or alternatively, the image retention
surface may itself comprise a record medium.
In one image development process sometimes termed polar liquid
development, a developer ink is delivered to the image retention
surface by a dispensing body. The liquid ink transfers from the
dispensing body to the retention surface by virtue of electrostatic
forces established by charged areas on the image retention surface.
The dispensing body generally comprises a roller having a surface
which contacts the image retention surface and which includes an
array of lands and grooves. The dispensing body is inked so as to
provide a supply of ink which is contained in the grooves of the
dispensing body. When the surface of the dispensing body is brought
into contactwith the surface bearing the latent electrostatic
image, the liquid development ink transfers from the grooves to the
image retention surface by virtue of electrostatic forces exerted
on the polar ink.
In order to reproduce an image with a clear background, it is
preferable that the lands of the dispensing body be free of ink and
that the grooves contain a level of ink which assures proper
electrostatic transfer to the image retention surface. These
requirements have therefore necessitated the use of ink applicator
doctoring apparatus which provides for the removal of ink from the
lands and for the reduction of the ink level within the grooves to
a predetermined level. Such doctoring apparatus has generally
comprised rigid, noncompressible doctor blades which are mounted in
a stationary location and which are positioned in contact with a
moving ink applicator body. The use of metallic or other
essentially rigid, noncompressible doctor bleades is accompanied by
various disadvantages which detract from the value of this method
of ink control. For example, it has been found relatively difficult
to initially adjust rigid blades in order to produce satisfactory
clean wiping of the lands. Rigid blades generally require a
break-in, or, alternatively a pre-grinding of the blade edges. In
addition, because of their rigidity, these blades do not dip into
the grooves appreciatively far beneath the level of the lands and
the control of the ink level within the grooves with rigid metallic
blades can only be obtained through the use of relatively higher
viscosity inks or higher applicator speeds. The use of higher
applicator speeds disadvantageously increases the wear on the
blades.
While some of these problems can be corrected by the use of
relatively soft metallic materials such as copper and brass, it has
been found to be relatively difficult to achieve a desired
uniformly sharp edge while the attending requirement for the
application of greater pressures to the doctor blades for wiping
the lands clean results in an undesirable and relatively large
depression of the ink in the grooves.
In various electrostatographic reproduction apparatus, it is
desirable to use polar developing inks or relatively low viscosity
It is found that the ink level in the applicator grooves shears
relatively close to the level of the lands when a rigid doctor
blade is employed. It is desirable that a relatively low viscosity
ink shear below the level of the lands in order to prevent direct
contact between the ink in the grooves and the photoreceptive
surface.
There is disclosed in my co-pending U.S. patent application which
is filed concurrently herewith and which is assigned to the
assignee of this invention, an improved ink doctoring arrangement
which utilizes an elastomeric material. The present invention is
elastomeric doctoring arrangement.
Accordingly, it is an object of this invention to provide an
improved ink applicator arrangement for a reproduction system.
Another object of the invention is to provide an improved ink
applicator arrangement for a liquid development electrostatographic
reproduction apparatus.
Another object of the invention is to provide an improved
arrangement for doctoring the level of ink on an ink applicator in
a reproduction system.
A further object of the invention is to provide an improved ink
applicator doctoring arrangement which is adapted for cleaning the
land areas on the applicator and for shearing relatively low
viscosity inks at a level below the land areas.
Another object of the invention is to provide a doctoring apparatus
which corrects one or more of the above enumerated
disadvantages.
In accordance with features of this invention, a reproduction
system includes an ink applicator body which is positioned adjacent
to a surface to be inked for transferring ink from said body to
said surface. The applicator body has an array of lands and
depressions formed on a surface thereof. A means for supplying ink
to the applicator is provided and an improved doctor means for
regulating the ink on the applicator includes an elongated body of
generally circular cross section which is formed of an elastomeric
material and means for mounting the elastomeric body in contact
with a surface of the applicator. Means provides relative motion
between the applicator body and the doctor body.
In accordance with more particular features of the invention, the
elastomeric body is supported in contact with the applicator
surface by a resilient body which effects a loading of the
elastomeric material against the moving applicator body. In
accordance with other features of the invention, the elongated body
of circular cross section comprises a cylinder of elastomeric
material. In accordance with another feature of the invention, the
elongated body of circular cross section comprises a tubular shaped
body of elastomeric material.
These and other objects and features of the invention will become
apparent with reference to the following specification and to the
drawing wherein:
FIG. 1 is a schematic view of a liquid development
electrostatographic reproduction apparatus constructed in
accordance with features of this invention;
FIG. 2 is a plan view of an ink applicator and ink doctoring
arrangement in accordance with one embodiment of this
invention;
FIG. 3 is a view taken along line 3--3 of FIG. 2;
FIG. 4 is an enlarged view of a portion of a doctoring arrangement
constructed in accordance with features of this invention and
illustrating an arrangement for loading an elastomeric doctoring
body against an ink applicator;
FIG. 5 is an elevation view of a support body for an elastomeric
doctoring body in accordance with this invention;
FIG. 6 is a perspective view of an elastomeric doctoring body
constructed in accordance with features of this invention;
FIG. 7 is a perspective view of an alternative embodiment of an
elastomeric doctoring body constructed in accordance with features
of this invention;
FIG. 8 is a side view of an alternative arrangement for supporting
and loading an elastomeric doctoring body against the surface of a
rotating ink applicator;
FIG. 9 is an enlarged view of a portion of the doctoring body
support means of FIG. 8; and,
FIG. 10 is a sbction view of the surface of an ink applicator
utilized in the apparatus of FIG. 1.
Referring now to FIG. 1, an electrostatic copying apparatus
employing liquid development includes a rotably mounted drum 8
having an image retention surface comprising, for example, a layer
10 of vitreous or amorphous selenium positioned on an outer surface
11 of the drum. The drum is continuously rotated in a
counterclockwise direction past a charging station 12 which
establishes a uniform electrostatic charge on the image retention
surface. The charging electrode 12 comprises, for example, a high
voltage corona discharge electrode adapted to supply ions or
electric charge to the image retention surface. The uniformly
charged image retention surface is rotated to an imaging station
13. There is positioned at the imaging station a means for
projecting an image on the charged surface for forming a latent
electrostatic image conforming to the original image. This means
includes a projection system including a lamp 14, a photographic
transparency 15 bearing an image which is to be reproduced, and a
lens 16 for focussing the image on the uniformly charged surface
10. The latent electrostatic image which is thus formed is rotated
by the drum to a development station referenced generally as 17. At
the development station, which is described in greater detail
hereinafter, the latent electrostatic image is developed and is
then transferred by the drum to an image transfer station 18 at
which location the image is transferred from the drum to a suitable
transfer web 20. The web 20 comprises for example a web of liquid
developer receptive paper or the like which is fed from a supply
roller 22 to a takeup roller 24 and passes between the drum 8 and a
transfer roller 26. After image transfer, the image retention
surface is rotated past a cleaning station designated generally as
28 where residual developer material, if any, is removed by a
rotating brush from the drum surface in order to prepare the drum
for recycling through the above-described operational stations.
Although a photoreceptive surface is shown in FIG. 1 to be formed
on the surface 11 of the drum, other forms of photoreceptor
surfaces known in the art can be employed. For example, a web or
sheet of zinc oxide recording medium can be transported by the drum
11 through various stations and can be used in place of the
transfer web 20. Alternatively, the web 20 can be replaced by sheet
collection station.
A development means is positioned at the development station 17 for
providing liquid development of the latent electrostatic image on
the image retention surface 10. The development means includes a
liquid developer applicator comprising a rotating drum 30, and
inking roller 32 and a reservoir 34 containing developer ink 36.
The drum 30 which is described in greater detail hereinafter has
deposited on its surface a film of ink for transport to the
rotating drum 8 and for application to the image retention surface
10. The development ink 36 is withdrawn from the reservoir 34 by
the inking roller 32, which is partially submerged in the ink, and
is conveyed and applied to the ink applicator drum 30. An ink
applicator doctoring arrangement 38 which is constructed in
accordance with features of this invention and which is described
in greater detail hereinafter is positioned for contacting a
surface of the rotating developer dispensing drum 30. The doctoring
means is provided for removing excess ink from the dispensing drum
30 after ink loading of the applicator and prior to transfer of ink
to the image retention surface.
The surface of the applicator dispensing member 30 of FIG. 1 is
shown in greater detail in FIGS. 2 and 10. The drum 30 is shown to
comprise a metal base 50 having a pattern formed on a surface
thereof by, for example, a plurality of fine raised lines, dots or
other geometrical configurations which result in a configuration of
lands 52 and valleys or depressions 54 located between the lands. A
triangular-helix-patterned gravure applicator drum has been found
particularly advantageous in that a two-walled structure of a
gravure cell of this configuration will yield less overall image
background with respect to other wall-to-wall gravure cell
configurations and any tendency for air entrapment in the
individual gravure cells is substantially diminished during the
inking operation. The surface of the drum 30 is characteristically
wettable by the liquid developer in the depressions or valleys
formed between the raised peak of the raised patterns but is
substantially nonwettable along the upper surface of the raised
lines or peaks. This is accomplished, for example, by the use of a
support base 50 having a relatively uniform surface and comprising
a material that is usually wettable by a liquid development
material employed.
The ink which is deposited on the surface of the applicator drum 30
comprises a polar ink which is contained in the valleys 54 on the
surface. The ink will transfer from these valleys to the image
retention surface 10 by creeping up the sides of the pattern
material and by migrating to the facing image on the receiving
surface 10. It is believed that the mechanism of developer
migration employs the cooperation of an electrostatic attractive
force and a surface tension force. The force of surface tension
retains the developer in cohesive configuration on the surface of
the applicator while electrostatic attraction applies forces which
cause the developer to creep up the sides of the patterned material
and to transfer only in accordance with the pattern of electric
charge on the surface 10. Thus, the developer ink remains in the
valleys of the applicator except when it comes under the influence
of an attractive electrostatic force on the surface 10.
As indicated hereinbefore, it is desirable to establish a
relatively free or clean background upon the transfer of the
development ink to the photoreceptive surface 10. This result is
accomplished when the lands 52 remain substantially free of ink
after the applicator is inked by a supply roll 32 and when the
level of the liquid ink in the valleys 54 is beneath that level at
which the ink would make physical contact with the photoreceptive
surface. In accordance with a feature of this invention, an
elongated body of elastomer material 56 of generally circular cross
section is positioned and supported with respect to the body 30 for
providing contact between the elastomer material 56 and the body
30. The elastomer material 56 is positioned in a groove 58 of an
elongated bar 60 and extends across the width of the applicator
drum 30. The grooved bar 60 is supported on a platform 62 which is
mounted between upright spaced apart support members 64 and 66. The
bar 60, which can be positioned at various locations along the
platform 62 is forced toward the right as viewed in FIGS. 3 and 4
and applies a loading force between the elastomeric doctoring body
56 and the surface of the applicator drum 30. A means comprising a
backing bar 68 which extends substantially coextensively with the
bar 60 and which bears against a rear surface, or alternatively
against other elastomeric bodies which are described in greater
detail hereinafter, is forced to the right as viewed in FIGS. 3 and
4 by a spring loading means. The spring loading means comprises
coil spring 70 which is connected to a stationary post 72 on the
upright body 64 and to a rod 74 which is secured to the backing
plate 68 and which extends through a groove 76 in the upright body
64, and, a coil spring 77 ?FIG. No. 2! is similarly connected
between a post 81 on the plate 68 and a stationary post 83 on the
upright 66. A resilient loading force is thereby established on the
elastomeric material 56 and urges it into contact with the surface
of the drum 30. While the elastomer material 56 is maintained in
contact with the drum 30 by virtue of the spring loading force
exerted thereon through the backing plate 68 and the bar 60, the
material can be secured in a fixed position when desired by locking
the bar 60 at a fixed location. This is accomplished as illustrated
in FIGS. 3 and 4 by a locking screw 78 which extends through a
threaded aperture in a plate 80. The plate 80 is mounted to and
extends between the uprights 60 and 66. Rotation of the locking
screw 78 forces the bar 60 against the platform 62 and locks it in
fixed position.
The doctoring body 56 comprises an elongated body of generally
circular cross section which extends across the width of the
applicator body 30. In accordance with one embodiment, the
elongated doctoring body comprises a cylindrically shaped body as
illustrated in FIG. 6. In an alternative arrangement, the
elastomeric doctoring body 56 comprises a tubular shaped elongated
body. While various elastomeric materials may be employed, a
preferred material from which the body 56 is fabricated comprises
neoprene rubber. The elastomeric body may be molded or extruded
within a range of diameters. A range of one-sixteenth to one-eighth
of an inch has been found to provide satisfactory operation.
The doctor body support bar 60 includes a plurality of grooves
formed along its length for supporting conventionally replaceable
doctor bodies when wear occurs in the material. In FIG. 5, the
elastomeric body 56 is shown fitted in the groove 58. When this
material exhibits signs of wear, the bar 60 can be reversed on the
platform 62 for positioning a replacement doctor body 82 against
the surface of the applicator drum 30. Additionally another groove
84 is formed in the bar 60 and an additional replacement doctor
body 86 is located in this groove. The bar 60 is then reversed and
inverted for positioning the replacement doctor body 86 in contact
with the surface of the drum 30. The grooves 58, 83 and 84 are
located on the bar for providing that a doctor body positioned
therein is brought into contact with the surface of the drum when
the bar 60 is forced toward the drum by the spring loading means
discussed hereinbefore. Alternatively, the grooves 58, 83 and 84
are dimensioned as illustrated in FIG. 5 for receiving doctor
bodies of different diameters for satisfying differing operational
requirements.
In an alternative arrangement in accordance with this invention for
positioning and loading an elastomeric doctoring body against the
surface of an ink applicator drum, the elastomeric material is
supported by a strip of relatively stiff and resilient material. In
FIGS. 8 and 9, an elastomeric doctoring body 56 of circular cross
section is supported against a surface of the applicator 30 by an
arcuate shaped segment 88 of an elongated spring metal strip 90.
The strip 90 is positioned between spacer members 93 and 94 and is
locked in place therein within the jaw of the doctor blade assembly
by hold down screw 96. The doctor blade assembly 92 includes rod
segments 98 which are rigidly secured thereto and which extend
through apertures 100 in spaced apart upstanding support bodies, 64
and 66. The doctor blade assembly which is thus pivotally supported
is biased against the surface of the applicator drum 30 by a spring
104 which is connected between a stationary post 106 and a lever
arm 110 which is coupled to the pivot rod 98. In addition to the
resilient biasing action provided by this spring loading, the strip
90 is formed of a resilient material which flexes during operation
and aids in establishing a desired loading between the elastomeric
material 56 and the surface of the drum 30. The strip 90 is formed
for example of brass shim stock and in a preferred embodiment, the
elastomeric material comprises a 1/8 inch diameter extruded
neoprene rubber which is cylindrical shaped as illustrated in FIG.
6 while the strip 90 comprises a 12 mil thickness of brass shim
stock.
Thus there has been described an improved ink applicator
arrangement for use with reproduction systems. The ink applicator
arrangement is particularly advantageous for use with relatively
low viscosity inks wherein the lands of an applicator body can be
wiped relatively clean while the level of ink within the valleys of
the applicator can be reduced to desired low levels. The background
of the reproduced image is thereby enhanced. A relatively uniform
loading of the doctoring body against the applicator drum is also
provided.
While I have described and illustrated particular embodiments of my
invention, various modifications may be made therein without
departing from the spirit of the invention and the scope of the
appended claims.
* * * * *