Squeegee roller for imaging systems

Imaging apparatus including squeegee apparatus for squeegeeing excess material from a surface, from which surface at least a portion of the material remaining after squeegeeing is to be transferred to another surface, comprising: a first surface, having a central portion and two end portions having recessed surfaces and having a liquid material thereon at least in said central portion, said surface moving in a given direction at a squeegee region; and a second, squeegee, surface, urged against at least the central portion of the first surface at the squeegee region and formed with contiguous end portions which mate with the recessed end surfaces of the first surface.

RELATED APPLICATION 
This application is a continuation of pending PCT Application 
PCT/NL95/00195, filed Jun. 6, 1995 which designated the United States, and 
claims priority under 35 U.S.C. 119 of Israeli Application No. 111,441, 
filed Oct. 28, 1994, the disclosures of which are incorporated by 
reference in their entirety. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to squeegeeing using moving squeegee rollers 
and more particularly to squeegee rollers for imaging apparatus employing 
liquid toners. 
2. Background and Material Information 
In processes for developing images on a photoconductor in imaging machines, 
especially those employing liquid toner or developer, images or layers of 
liquid toner are often squeegeed in order to remove excess liquid or 
excess toner from the image or the layer. This is generally done by urging 
a squeegee roller (or another moving squeegee surface) together with the 
surface supporting the image or layer. The squeegee roller surface rides 
on the image or layer supporting surface and the two surfaces move in the 
same direction, generally at the same velocity. When the supporting 
surface is a roller coated with liquid toner concentrate this surface 
typically contacts or is in close proximity with a photoreceptor, such as 
a selenium drum or an organic photoconductor, which carries the latent 
image to be developed. Such systems are disclosed in Patent publications 
WO 93/01531 and WO 94/16364, the disclosures of which is incorporated 
herein by reference. 
Alternatively, a squeegee is utilized to remove excess carrier liquid from 
an already developed image on a photoreceptor or other surface. One such 
use of a squeegee roller is described in U.S. Pat. No. 5,028,964, the 
disclosure of which is incorporated herein by reference. 
In the system described in WO 94/16364, a toner injector injects a quantity 
of liquid toner onto a rotating developer roller. A (preferably 
electrified) squeegee roller is urged against the developer roller and 
compacts and concentrates the liquid toner by removing a portion of the 
liquid therefrom to form a substantially uniform layer of concentrated 
liquid toner on the developer roller. During the squeegee operation excess 
toner and excess carrier liquid removed from the layer are carried toward 
the ends of the squeegee roller and "run" around the end of the rollers 
and onto the edge of the developer roller. 
A photoreceptor containing a latent image is brought into operational 
association with the developer roller to develop the latent image by the 
selective transfer of all or a portion of the concentrated liquid toner 
layer formed on the developer roller. Excess liquid toner and carrier 
liquid removed from the toner which is carried along the edge of the 
roller have a tendency to contaminate the edges of the image developed on 
the photoreceptor and to form strips of liquid toner on the photoreceptor 
which are later transferred to a final substrate. 
SUMMARY OF THE INVENTION 
The present invention seeks to provide a solution to such edge 
contamination in an imaging machine such as a copier or printer. 
In one aspect of the invention a recessed surface such as a beveled surface 
is provided at the edges of a developer surface, such as the surface of a 
developer roller or developer belt. The end of the developer surface, 
which may be contaminated by excess toner, is thus not in contact with the 
photoreceptor to which the remainder (the central portion) of the 
developer surface selectively transfers the layer of liquid toner formed 
on the developer surface. Any excess (untransferred) liquid toner present 
on the developer surface, including the material at the end of the 
surface, is removed from the surface after it leaves the photoreceptor 
surface at a cleaning station which can be of any suitable design. 
In a second aspect of the invention, in which a squeegee roller is used to 
compress and concentrate a liquid toner image already formed on an imaging 
surface such as a photoreceptor, the photoreceptor is provided with a 
beveled edge which is not in contact with a final substrate (or an 
intermediate transfer member) during transfer of the compressed image 
thereto. The excess liquid or toner at the edges of the photoreceptor is 
removed therefrom together with any untransferred portions of the image at 
a cleaning station which can be of any suitable design. 
There is thus provided, in accordance with a preferred embodiment of the 
present invention, imaging apparatus including: 
an imaging surface, having a latent electrostatic image formed thereon, 
which moves in a given direction at a development region; 
a developer surface, preferably the surface of a developer roller, having a 
central portion and at least one recessed, preferably beveled, end, the 
central portion being urged against the imaging surface and moving 
therewith at a development region; and 
a squeegee surface, preferably the surface of a squeegee roller, urged 
against at least the central portion of the developer surface at a 
squeegee region, prior to the development region. 
Preferably, the squeegee surface is formed with end portions which mate 
with the recessed ends of the developer surface. 
In a preferred embodiment of the invention, the apparatus further comprises 
a toner injector which deposits a quantity of liquid toner onto the 
developer surface prior to the squeegee region. Preferably the apparatus 
includes a developer surface cleaning station which removes excess toner 
from the developer surface after it leaves the development region. 
There is further provided, in accordance with a preferred embodiment of the 
invention, imaging apparatus: 
an imaging surface, preferably an imaging drum, having a central portion 
and two recessed, preferably beveled, ends and having a liquid toner image 
formed on said central portion, which moves in a given direction at a 
squeegee region; 
a squeegee surface, preferably the surface of a squeegee roller, urged 
against at least the central portion of the imaging surface at the 
squeegee region. 
Preferably, the squeegee surface is formed with end portions which mate 
with the recessed ends of the imaging surface. 
Preferably the apparatus includes an imaging surface cleaning station which 
removes excess toner from the imaging surface after it leaves the squeegee 
region. 
There is further provided, in accordance with a preferred embodiment of the 
invention, squeegee apparatus for squeegeeing excess material from a 
surface from which surface at least a portion of the material remaining 
after squeegeeing is to be transferred to a second surface comprising: 
a first surface, preferably the surface of a drum, having a central portion 
and two recessed, preferably beveled, ends and having a liquid material 
thereon at least in said central portion, which moves in a given direction 
at a squeegee region; and 
a squeegee surface, preferably the surface of squeegee roller, urged 
against at least the central portion of the imaging surface at the 
squeegee region. 
Preferably, the squeegee surface is formed with end portions which mate 
with the recessed ends of the first surface.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Reference is made to FIG. 1 which is a generalized illustration of a 
portion of an imaging machine constructed and operative in accordance with 
a preferred embodiment of the present invention. Only those portions of 
the imaging apparatus necessary to illustrate the invention are included 
in FIG. 1, the other parts of the apparatus being entirely conventional 
and very well known in the art. 
A liquid toner injector 14 injects liquid toner or liquid toner concentrate 
onto a counter-clockwise rotating developer roller 12. A clockwise 
rotating squeegee roller 10 is urged against the developer roller 12 at a 
squeegee region 50. 
In a preferred embodiment of the invention, squeegee roller 10 is 
electrified to compress the liquid toner layer, spread by toner injector 
14, and to remove excess toner by the squeegee action. Squeegee roller 10 
thus concentrates the liquid toner and forms a layer thereof on the 
developer roller as it leaves the squeegee region. Alternatively, any of 
the apparatus shown in the aforementioned publications WO 93/16364 or WO 
93/01531 may be used to form the layer of liquid toner concentrate on 
developer roller 12. 
Developer roller 12 is brought into operational juxtaposition with a 
photoreceptor drum 16 which has a latent image formed thereon at a 
development region 52, the latent image having image areas at a first 
potential and background areas at a second potential. Developer roller 12 
is electrified to a potential between the first and second potentials such 
that at least a portion of the liquid toner layer thereon is selectively 
transferred from the developer roller to the image areas of the 
photoreceptor. Such development is described in the aforementioned WO 
93/16364 or WO 93/01531. 
A cleaning station 18, downstream of development region 52, removes toner 
and carrier liquid which is not transferred to the photoreceptor. While 
cleaning station 18 is shown as comprising only a squeegee blade, it may 
consist of any of the many cleaning stations known in the art and may 
include a roller or rollers, a brush or brushes and/or a supply of carrier 
liquid. 
Reference is now made to FIG. 2, which shows a combination of squeegee 
roller 10 having edges 20, developer roller 12 having edges 22 and 
photoreceptor 16 as known in the prior art. 
As described above, squeegee roller 10 is urged against developer roller 12 
to form a layer of concentrated liquid toner comprising charged toner 
particles and carrier liquid, on developer roller 12; liquid toner or 
liquid toner concentrate having been supplied to either or both rollers 
prior to their coming into contact or at the point of contact. Developer 
roller 12 is brought into operational juxtaposition with photoreceptor 
drum 16 which has a latent image formed thereon, the latent image having 
image areas at a first potential and background areas at a second 
potential. Developer roller 12 is electrified to a potential between the 
first and second potentials such that at least a portion of the liquid 
toner layer thereon is selectively transferred from the developer roller 
to the image areas of the photoreceptor. 
During the squeegee action on the layer of liquid toner, excess liquid 
toner and carrier liquid migrate to the edges 20 and 22 of squeegee roller 
10 and developer roller 12 respectively. As squeegee roller 10 and 
developer roller 12 rotate, the excess toner collected at edge 22 is 
transferred to the surface of photoreceptor 16 and contaminates it. 
Reference is now made to FIG. 3, which is a generalized illustration of a 
portion of an imaging machine constructed and operative in accordance with 
a preferred embodiment of the present invention. FIG. 3 shows a squeegee 
roller 10', a developer roller 12' and a photoreceptor drum 16, all of 
which rotate together. The general functions of these elements are the 
same as those of the corresponding elements in the prior art device shown 
in FIG. 2, however the developer roller and, preferably, the squeegee 
roller are shaped so as to avoid the problems of the prior art systems as 
described above. 
In the embodiment of FIG. 3, developer roller 12' has beveled ends 26. 
Preferably, squeegee roller 10' is formed with ends 24 which conform to 
edges 26 such that the entire surface of the developer and squeegee 
rollers are in contact and the entire surface of the developer roller is 
squeegeed by the squeegee roller. As shown in FIG. 3, ends 24 and 26 are 
cone shaped such that end 24 of squeegee roller 10' forms a diverging cone 
whereas the beveled end 26 of developer roller 12' forms a converging 
cone. 
As in the prior art, excess liquid toner and carrier liquid, which is 
squeegeed from the layer of liquid toner formed on the developer roller, 
migrate to the ends of the rollers. However, unlike the ends of developer 
roller 12 shown in FIG. 2, the ends of developer roller 12' are not in 
contact with the surface of photoreceptor 16 and liquid is thus not 
transferred to the photoreceptor from the ends of the developer roller, 
the amount of beveling being sufficient to avoid contact of the liquid on 
the ends 26 with photoreceptor 16. 
It is to be appreciated that different cone angles may be employed as long 
as the cone angle and length of the bevel is sufficient to avoid contact 
of the liquid on the end of the developer roller with the photoreceptor 
surface. 
Generally speaking, for proper squeegee action one or both of rollers 10' 
and 12' should be of a resilient material such as an elastomer, or have a 
resilient coating. 
The present invention, while illustrated for a particular preferred 
embodiment, is also suitable for any squeegeeing situation in which the 
squeegeed material on a first surface is to be transferred to a further 
surface and the transfer of excess material at the edges of the first 
surface is to be avoided. 
One such situation is illustrated in FIG. 4, in which an imaging surface 
30, for example a photoreceptor roller, has a developed image comprising 
charged toner particles and carrier liquid formed thereon. Imaging surface 
30 is formed with beveled ends. A squeegee surface such as a squeegee 
roller 32, preferably having ends which match the bevel on the imaging 
surface, is urged against the imaging surface and is preferably 
electrified to compress and concentrate the image and to remove carrier 
liquid therefrom. The amount of carrier liquid which may be on the 
non-image portions of the imaging surface is also reduced by the action of 
the squeegee. Such squeegee action on images is described in the 
aforementioned U.S. Pat. No. 5,028,964. 
The thus-removed carrier liquid migrates to the edge of rollers 30 and 32. 
When the photoreceptor comes in contact with a further surface 34, such as 
a final substrate or an intermediate transfer member, to which the image 
is to be transferred, this liquid, which may contain some toner particles, 
may be transferred to the surface 34. 
In this embodiment of the invention, the ends of imaging surface 30 are 
beveled such that liquid at said ends is not transferred to further 
surface 34. Preferably, the ends of squeegee roller 32 are formed to mate 
with the beveled edges of imaging surface 30. 
While the invention has been shown using the preferred beveled cone shaped 
ends, other end shapes, such as undercuts (i.e., a smaller diameter at the 
ends) on the developer roller 12' of FIG. 3 or the imaging surface 30 of 
FIG. 4 can be used. 
It will be appreciated by persons skilled in the art that the present 
invention is not limited by what has been particularly shown and described 
hereinabove. Rather the scope of the present invention is defined only by 
the claims which follow: