CA1050829A - Electrostatic image development using development electrode with rough surface - Google Patents
Electrostatic image development using development electrode with rough surfaceInfo
- Publication number
- CA1050829A CA1050829A CA229,043A CA229043A CA1050829A CA 1050829 A CA1050829 A CA 1050829A CA 229043 A CA229043 A CA 229043A CA 1050829 A CA1050829 A CA 1050829A
- Authority
- CA
- Canada
- Prior art keywords
- development
- development electrode
- toner
- rough surface
- developed
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000007788 liquid Substances 0.000 claims abstract description 45
- 238000000034 method Methods 0.000 claims description 9
- 239000002245 particle Substances 0.000 claims description 5
- 239000004020 conductor Substances 0.000 claims 1
- 239000007921 spray Substances 0.000 description 7
- 230000002093 peripheral effect Effects 0.000 description 3
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 241000370685 Arge Species 0.000 description 1
- 101100029872 Dictyostelium discoideum pitC gene Proteins 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
- 238000000059 patterning Methods 0.000 description 1
- 238000001259 photo etching Methods 0.000 description 1
- 238000007788 roughening Methods 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
- G03G15/10—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer
- G03G15/101—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer for wetting the recording material
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Wet Developing In Electrophotography (AREA)
- Electrophotography Using Other Than Carlson'S Method (AREA)
Abstract
Application for Patent of Heino Kase for LIQUID DEVELOPMENT OF ELECTROSTATIC IMAGES
ABSTRACT OF THE DISCLOSURE
In a liquid development station for developing electrostatic latent charge images on the charge retentive surfaces of recording media, a cylindrical development electrode is mounted for rotation adjacent the charge retentive surface of a recording medium to be developed. The cylindrical development electrode has a rough surface and is rotated with sufficient angular velocity such that the speed of the rough surface is faster than the speed of the moving charge image to be developed. Liquid electrographic toner is supplied to the rough surface of the rotating development electrode so as to be carried by the rotating rough surface into contact with the charge image to be developed.
ABSTRACT OF THE DISCLOSURE
In a liquid development station for developing electrostatic latent charge images on the charge retentive surfaces of recording media, a cylindrical development electrode is mounted for rotation adjacent the charge retentive surface of a recording medium to be developed. The cylindrical development electrode has a rough surface and is rotated with sufficient angular velocity such that the speed of the rough surface is faster than the speed of the moving charge image to be developed. Liquid electrographic toner is supplied to the rough surface of the rotating development electrode so as to be carried by the rotating rough surface into contact with the charge image to be developed.
Description
B~C~GROUND O~ TIIE INVENTION
~ c prcsent invcntion rclates in gcncral to liquid devclopmcnt of electrostatic char~e ima~cs ;ln~ more particu1;1rly ////
////
.
~ ' :
., ~, . ~ - , ,,, -, --, .
:
.
-. .
~ ~5~g8 2~
to a method and app.lratlls cmploying a rotat.lble dcveloplllent electrodc for carrying elcctrographic toncr into contact with the charge images to be dcveloped.
DESCRIPTION OF TIIE PRIOR ART
llerctofore~ electrostatic charge images on the charge retentive surface of the recording web have been developed with liquid electrographic ~oner. In SUC]l systems, the development station included a rotating cylindrical drum-shaped development electrode. The drum-shaped electrode was mounted adjacent the 10: large image bearing surface of the recording medium. The lower portion of the drum dipped into a bath of liquid toner so as to pick up toner on the smooth surface of the drum and carry it ~nto contact with the charge images on the charge retentive surfaces to ~e developed. The drum was rotated with sufficient angular velocity~such that the peripheral speed of the drum exceeded the speed of the web being developed so as to establish a ~ead of liqui~d toner between the outer surface of the rotating drum and the charge retentive surface to be developed. Such a devel~pment station is disclosed in U.S. Patent 3,367,791 issued 20: February 6, 1968.
~Yhile suc~ a development station is suitable for developing images moving at a relatively slow speed it is generally unsatisfactory for developing images on charge retentive surfaces of recording webs traveling at relatively high speeds, such as ; faster than two inches per second, because the angular and peripheral velocity of the developmcnt electrode must be relatively high to provide the necessary amount of toner to the images being developed, particularly when the images include relatlvely large dark areas ~hicll are to be developed with a 3Q. uniform degree of darkness.
/l/~
. .
1050~ZC~ ~
It has also been proposed, in the prior art, to utilize a porous or perforated drum-shaped development electrode with means inside the electrode for forcing elec,$rographic liquid toner through the porous walls of the drum against the charge retentive surface of the recording web to be developed. In one embodiment, the drwn was rota~ed at the same speed as the speed of the recording web ~eing developed. Such a device forms the subject matter of U.S. Patent 3,618,567 issued November 9, 1971 and assigned to t~e same assignee as the present invention. In ;~
la another such device, a perforated development electrode drum was rotated at a sufficient angular velocity such that the surface of the drum adjacent the charge retentive surface being de'yeloped was approximately up to ten times the speed of the image ~ , bearing we~ ~eing developed. This higher differential speed allowe'd the drum to disturb the bounda~y laye~ of liquid toner ~hich'~ould ordinarily form adjacent the surface of the moving j recording we~ to be developed. This boundary layer interferes ~ith complete 'development ~ecause it soon becomes depleted of the electrographic toning paTticles. This depleted layer is 20: preferably removed so as to allow fresh electrographîc toner to contact t~e charge image to be developed. This latter differential speed perforated development electrode forms the , subject matter and is claimed in u~S. Patent 3,952,702, issued April 27, 1976, and assigned to the same assignee as ~h~
present invention.
While such perforated or porous development electrode drums are capable of developing relatively large areas at relatively high speeds, such as tens of inc~es per second, they are cumbersomc assemblies and are relatively difficult to abricate and tllUS are more costly than impcr~orate drumsO
~ ' 1/1/
; 3 '~ ' '''' . ' .. . ., . . . . , ., .. ~.,.. - . ~ .
~050829 Thus it would be dcsiral~lc to provide an impro~ed rotat<lble developmcnt electrode which is capable of operating at relatively high wcb speeds, which is easy to -fabricate and assemblc, and whic h does not have ~o be driven at such hig}l angular velocity as here-tofore encountered with smooth imperforate development drums.
SV~RY OF T~IE PRESr:NT INVENTION
The principal object of the present invention is the provision of an improved method and apparatus for liquid development of electrostatic charge images.
lQ In one feature of the present invention, the development ~tation includes a cylindrical developmen~ electrode having a rough outer surface to be rotated adjacent the charge retentive surface of tHe recording medium being developed. This rough surface serves to facilitate the carrying of liquid toner to the charge images being developed and to disrupt the boundary layer of liquid toner other~ise tending to form adjacent the charge i~ages to be developed, ~hereby improved liquid electrographic development ;s o~tained.
In another feature of the present invention,`liquid ; 20: electrographic toner is applied to the rough surface of a cylindrical development electrode by directing a stream of liquid develu~ment toner against the outer rough surface of the ; development electrode. The toner is preferably applied to a region of the rotatable development electrode which is moving toward the charge image bearing surface to be developed.
In another feature of the present invention, the outer surface of a cylindrical development electrode includes an array of lands and grooves such lands and grooves being elongated and running transverse to the direction of rotation of the developmcnt elcctrode.
/l//
/l//
f~' ~ 4 s~
In accordance with the foregoing features, there is more par~icularly provided:
In a method of developi.ng electrostatic latent charge images on charge retentive surfaces the steps of:
mounting an electrically conductive development electrode with a rough outer cylindrical surface thereof for rotation about i~s axis of revolution;
passing the charge retentive surface of a recording medium, bearing a latent charge image thereon to be developed, adjacent said rough surface of the cylindrical development electrode;
rotating said cylindrical development electrode with an angular velocity such that the rough surface of said development electrode is moving at a different speed than that o the charye retentive surfaces to be developed; and supplying liquid electrographic development toner, having electroscopic toner particles suspended in a dielectric liquid, to the rough surface of said development electrode so that the toner liquid is brought into contact with the charge images to be developed for developing same.
There is also provided:
In an apparatus for developing electrostatic images on a charge retentive surface:
development electrode means having a rough cylindrical surface comprising a plurality of discrete pro~
jecting surface portions, separated from one another by a plurality of recessive surface portions;
means for mounting said development electrode means for rotation about its axis of revoulution;
means for passing the charge retentive surface of a ~ recording medium, for bearing latent charge images thereon :~ to be developed, adjacent said rough surface of said development .
~ 4a-.,~
;'~' ~.. - - . , .
5~82~
electrode and contiguous with said projectlng surface portions thereof;
means for rotating said development electrode means with an angular velocity such that said rough surface of said development electrode moves at a differellt speed than that of . .
the adjacent charge retentive surface to be developed; and means for supplying liquid electrographic development toner, having electroscopic toner partic:Les suspended in a d~electric liqu~d, to t~e rough surface of said development ~ :
electrode so t~a~ the toner liquid is carried into contact wi~h the charge images on the charge retentive surface to be developed for developing same, said liquid toner being carried within said recessive surface portions, said projecting surface portions serving to wipe liquid toner from said charge retentive s~rface, whereby said charge retentive surface undergoes a plurality of successive development operations, each o said operations being followed by a wiping operation~
: ' ' .
-4b- ;
`::
~''' .
Otller ic;lturcs ~n~l adv;llltllgcs Or the prcscnt invcntion will becomc ~pl~aren~ upon a per~lsal of the ~ollowing spccificcltion takcn in connection with the accompanying drawings wherein:
~RIEF D~JSCR~PTION OF TIIE DRAWINGS
Fig. 1 is a transversc sectional view of a liquid electrographic developmcnt station incorporating features of the present invention, and Fig. 2 is an enlarged detail view of a portion of the structure of Fig. 1 delineated by line 2-2.
DESCRIPTION OF T~IE PRE~ERRED E,~BODIMENTS
_ Referring now to Fig. 1 there is shown a liquid electrographi development station 1 incorporating features of the present invention. Electrographic recording paper 2 is pulled through the development sta~ion 1 by passing through the nip of a pair af rollers 3 and 4~ Roller 4 is a squeegee roller having a compressible layer 5 on the outer surface thereof and such layer ~eing compressed against the other roller 3, as of stainless steel, to provide a frictional drive for the paper web 2 sand-wlched ~etween the two rollers 3 and 4. The squeegee roller 4 2Q' is driven in the clockwise direction via any one of a number of conventional drive means, such as a gear train or V-belt, not shDwn ~
The electrograp~ic recording paper 2 is threaded between an idler roller 5, as of stainless steel, and a development electrod roller 6, as of aluminum. Rollers 3 and 5 are positioned relativ to the development roller 6 so as to cause the electrographic recording web 2 to be pressed into nominal engagement with a portion of the surface of tlle developmcnt ~le~rOde 6. A V-belt power take of of ~he squeegee roller 4 is passed over an idler pulley 8 which in-turn drives the developmcllt roller 6 via a ///l ~///
11a 5C~8~:9 second V-bcIt ~Irivc ~. 'I'he pu]ley ratios are chosen so that t~.e peripheral spocd of the development electrode 6 is within the rangc of 2 to S times thc speed of the electrographic recording web 2 which is to be developed. Any one of a number of drive means, such as gear trains9 etc., ~.ay be employed as an alternati e to the V-belt drives 7 and 9.
Liquid electrographic toner is applied to the development drum via a spray pipe ll which directs a stream 12 of liquid toner against the outer cylindrical su~face 13 of the development electrode 6 in a region where the direction of movement of the development electrode 6 is toward the electrographic web 2 to be developed. The liquid electrographic toner comprises a dielectric liquid vehicle having a suspension of charged pigmented toner particles therein. The toner is drawn from a reservoir 14 and supplied to the spray pipe ll via a pump 15 and conduit 16. A spray shield 17 is interposed between the spray pipe 11 and the electrographic web 2 to prevent unwanted spraying of the electrographic toner directly OTltO the web 2.
The electrographic recording web 2 includes a conductive ` 20 paper backing having a dielectric insulative layer coated thereon `~ to form a charge retentive surface. Charge images to be developed are deposited upon the charge retentive surface and carried by the web 2 into the development station 1. The charge retentive layer is disposed -facing the development drum 6.
Rollers 3 and 5 make electrical contact to the conductive side of the web and the development electrode drum 6 may be operated at a floating potential relative to the potentials applicd to rollers 3 and 5 or the development drum 6 may be operated at a suitable development potential relative to the potentials applie to rollers 3 and S.
Referring now to ~i~. 2 there is shown the surface detail of the dcvclopmcnt electrode drum 6. The outer surface l3 o~ the .' ', ' ', . ~ . ' ' . ' ' . ' ' . . ' ~ .
~508~g drum 6 is rough, and in a prc~erre(l cmbodiment comprises an array of relatively thln longitudinally directed lands 21 separated by wider groove portions 22. In a typical example, the~ lands 21 have a height of approximately 0.050 :inch relative to the bottom of the groove portions 22. In operat:ion, the land portions 21 serve as wipers for wiping the depleted boundary layer of toner from tlle charge retentive surface of the recording web 2.
The groove regions 22 between adjacent lands 21 serve to carry - fresh toner into contact with the charge images to be developed lQ.'. on th.e recording web 2.
In addition, the ~ottom surface of the grooves 22 serves the function of the development electrode, namely, to provide a conductive surface operating at a different potential than that of the ch.arge images to be developed so that the field lines will extend betwe'en` the' charge images and the adjacent surface of the development elec'trode 6. In this manner the electric fields in the electrograph.ic toner region between t~e development electrode : 6 and the charge retentive surface are relatively high to pedite transfer of toner particles from the electrographlc 20 . toner liquid to the charge images to be developed. In a ' preferred embodiment, the groove portions 22 are wikhin 0.100 inc or less of the charge image ~eing developed. The land regions 21 ;~ should be relatively narrow relative to the groove region 22 so that nominal contact is established between the upper surfaces of the lands 22 and the charge retentive surface so as to :` efficiently disrupt the.boundary layer of'depleted toner adjacent the web 2.
In addition, the lands 21 should have a slight pitch relative to the axis of revolution of the development electrode 6 so that the paper web 2, particularly in the case of a fan-fold l/l/
/tl/
~ Q5~D~ Z~
elcctrograpllic web, ~loes not get c~ught and torn by the more rapidly moving peripllcral surfacc of the ~leveloprnent electrode 6.
The spiral pitC]I o~ the lands is suff:icient iE the pitch has advanced by one angular land period over the length of the development electrode 6. Furthermore, the surface 13 of the development electrode should be free of surface detail which is invariant in the direction of rotation of the development electrod e to prevent streaking and patterning of the developed image.
As an alternative to a surface roughness detai:L consisting of lands and grooves, the surface of the development electrode may be roughened ~y sand ~lasting, photoetching, or knurling.
Generally speaking, the rough surface 13 should have surface detail thereon ~aving mean peak-to-peak amplitude variations of between q.005 and 0.100 inch.
In an alternative embodiment oE the present invention, the development electrode drive can be arranged for driving the develop~ent electrode in a direction counter to the direction ; of ~oYement of the electrograp~ic we~ 2O In such an embodiment, ~; the Y-belt ta~e of drive 7 is moved to the back up roller 3 so20: a~ to drive the development electrode 6 in the counter-clockwise I direction. In this latter embodiment, the spray pipe 12 is preferably moved to a region adjacent the first quadrant of the developmént electrode so that the electrographic toner is sprayed onto the roughened surface o-f the surface 13 of the drum in a region moving toward the charge retentive surface to be de~eloped.
Although the surface roughening feature of the developmen~
electrode is, in a preferred embodiment, applied to an imperforate development electrode drum 6 this is not a requirement. It may be also used to advantage with perforated ~/!/
,.;, , .. . . . . . .
., ~ . .
' ' ' ~ ' ' '~ . ' ':
: . . . .
~ 2 ~
or porous dcvcloplllcnt olcctrodc drums whcreirl thc electrograp}lic toner is pumpcd througll the pcr:forated wall of the dcvelopment drum into contact Wit]l the charge retentive surface of the record.ing medium to be dcveloped. In the case of the perforated development electrode drum, the lands function in ~he same manner as previously described wit.h regard to the embodiment of Fig. 1 wherein the lands 21 serve to disrupt the boundary layer of depleted toner adjacent the charge retentive sur~ace of the recording web 2.
The differential speed between the speed o~ the recording web 2 and that of the periphery of the development electrode 6 is preferably at least twice the speed of the web 2.
An advantage of the spray method of supplying liquid toner to the development electrode, as contrasted with the method of dip~ing the lower part of the rotating drum in :Liquid toner, is that the spray tends to scrub away depleted toner from the surface of the drum due to its turbulent impact with the drum.
//// .
///~
//~/
//ll ////
////
////
////
////
////
////
//// .
~ .
~ c prcsent invcntion rclates in gcncral to liquid devclopmcnt of electrostatic char~e ima~cs ;ln~ more particu1;1rly ////
////
.
~ ' :
., ~, . ~ - , ,,, -, --, .
:
.
-. .
~ ~5~g8 2~
to a method and app.lratlls cmploying a rotat.lble dcveloplllent electrodc for carrying elcctrographic toncr into contact with the charge images to be dcveloped.
DESCRIPTION OF TIIE PRIOR ART
llerctofore~ electrostatic charge images on the charge retentive surface of the recording web have been developed with liquid electrographic ~oner. In SUC]l systems, the development station included a rotating cylindrical drum-shaped development electrode. The drum-shaped electrode was mounted adjacent the 10: large image bearing surface of the recording medium. The lower portion of the drum dipped into a bath of liquid toner so as to pick up toner on the smooth surface of the drum and carry it ~nto contact with the charge images on the charge retentive surfaces to ~e developed. The drum was rotated with sufficient angular velocity~such that the peripheral speed of the drum exceeded the speed of the web being developed so as to establish a ~ead of liqui~d toner between the outer surface of the rotating drum and the charge retentive surface to be developed. Such a devel~pment station is disclosed in U.S. Patent 3,367,791 issued 20: February 6, 1968.
~Yhile suc~ a development station is suitable for developing images moving at a relatively slow speed it is generally unsatisfactory for developing images on charge retentive surfaces of recording webs traveling at relatively high speeds, such as ; faster than two inches per second, because the angular and peripheral velocity of the developmcnt electrode must be relatively high to provide the necessary amount of toner to the images being developed, particularly when the images include relatlvely large dark areas ~hicll are to be developed with a 3Q. uniform degree of darkness.
/l/~
. .
1050~ZC~ ~
It has also been proposed, in the prior art, to utilize a porous or perforated drum-shaped development electrode with means inside the electrode for forcing elec,$rographic liquid toner through the porous walls of the drum against the charge retentive surface of the recording web to be developed. In one embodiment, the drwn was rota~ed at the same speed as the speed of the recording web ~eing developed. Such a device forms the subject matter of U.S. Patent 3,618,567 issued November 9, 1971 and assigned to t~e same assignee as the present invention. In ;~
la another such device, a perforated development electrode drum was rotated at a sufficient angular velocity such that the surface of the drum adjacent the charge retentive surface being de'yeloped was approximately up to ten times the speed of the image ~ , bearing we~ ~eing developed. This higher differential speed allowe'd the drum to disturb the bounda~y laye~ of liquid toner ~hich'~ould ordinarily form adjacent the surface of the moving j recording we~ to be developed. This boundary layer interferes ~ith complete 'development ~ecause it soon becomes depleted of the electrographic toning paTticles. This depleted layer is 20: preferably removed so as to allow fresh electrographîc toner to contact t~e charge image to be developed. This latter differential speed perforated development electrode forms the , subject matter and is claimed in u~S. Patent 3,952,702, issued April 27, 1976, and assigned to the same assignee as ~h~
present invention.
While such perforated or porous development electrode drums are capable of developing relatively large areas at relatively high speeds, such as tens of inc~es per second, they are cumbersomc assemblies and are relatively difficult to abricate and tllUS are more costly than impcr~orate drumsO
~ ' 1/1/
; 3 '~ ' '''' . ' .. . ., . . . . , ., .. ~.,.. - . ~ .
~050829 Thus it would be dcsiral~lc to provide an impro~ed rotat<lble developmcnt electrode which is capable of operating at relatively high wcb speeds, which is easy to -fabricate and assemblc, and whic h does not have ~o be driven at such hig}l angular velocity as here-tofore encountered with smooth imperforate development drums.
SV~RY OF T~IE PRESr:NT INVENTION
The principal object of the present invention is the provision of an improved method and apparatus for liquid development of electrostatic charge images.
lQ In one feature of the present invention, the development ~tation includes a cylindrical developmen~ electrode having a rough outer surface to be rotated adjacent the charge retentive surface of tHe recording medium being developed. This rough surface serves to facilitate the carrying of liquid toner to the charge images being developed and to disrupt the boundary layer of liquid toner other~ise tending to form adjacent the charge i~ages to be developed, ~hereby improved liquid electrographic development ;s o~tained.
In another feature of the present invention,`liquid ; 20: electrographic toner is applied to the rough surface of a cylindrical development electrode by directing a stream of liquid develu~ment toner against the outer rough surface of the ; development electrode. The toner is preferably applied to a region of the rotatable development electrode which is moving toward the charge image bearing surface to be developed.
In another feature of the present invention, the outer surface of a cylindrical development electrode includes an array of lands and grooves such lands and grooves being elongated and running transverse to the direction of rotation of the developmcnt elcctrode.
/l//
/l//
f~' ~ 4 s~
In accordance with the foregoing features, there is more par~icularly provided:
In a method of developi.ng electrostatic latent charge images on charge retentive surfaces the steps of:
mounting an electrically conductive development electrode with a rough outer cylindrical surface thereof for rotation about i~s axis of revolution;
passing the charge retentive surface of a recording medium, bearing a latent charge image thereon to be developed, adjacent said rough surface of the cylindrical development electrode;
rotating said cylindrical development electrode with an angular velocity such that the rough surface of said development electrode is moving at a different speed than that o the charye retentive surfaces to be developed; and supplying liquid electrographic development toner, having electroscopic toner particles suspended in a dielectric liquid, to the rough surface of said development electrode so that the toner liquid is brought into contact with the charge images to be developed for developing same.
There is also provided:
In an apparatus for developing electrostatic images on a charge retentive surface:
development electrode means having a rough cylindrical surface comprising a plurality of discrete pro~
jecting surface portions, separated from one another by a plurality of recessive surface portions;
means for mounting said development electrode means for rotation about its axis of revoulution;
means for passing the charge retentive surface of a ~ recording medium, for bearing latent charge images thereon :~ to be developed, adjacent said rough surface of said development .
~ 4a-.,~
;'~' ~.. - - . , .
5~82~
electrode and contiguous with said projectlng surface portions thereof;
means for rotating said development electrode means with an angular velocity such that said rough surface of said development electrode moves at a differellt speed than that of . .
the adjacent charge retentive surface to be developed; and means for supplying liquid electrographic development toner, having electroscopic toner partic:Les suspended in a d~electric liqu~d, to t~e rough surface of said development ~ :
electrode so t~a~ the toner liquid is carried into contact wi~h the charge images on the charge retentive surface to be developed for developing same, said liquid toner being carried within said recessive surface portions, said projecting surface portions serving to wipe liquid toner from said charge retentive s~rface, whereby said charge retentive surface undergoes a plurality of successive development operations, each o said operations being followed by a wiping operation~
: ' ' .
-4b- ;
`::
~''' .
Otller ic;lturcs ~n~l adv;llltllgcs Or the prcscnt invcntion will becomc ~pl~aren~ upon a per~lsal of the ~ollowing spccificcltion takcn in connection with the accompanying drawings wherein:
~RIEF D~JSCR~PTION OF TIIE DRAWINGS
Fig. 1 is a transversc sectional view of a liquid electrographic developmcnt station incorporating features of the present invention, and Fig. 2 is an enlarged detail view of a portion of the structure of Fig. 1 delineated by line 2-2.
DESCRIPTION OF T~IE PRE~ERRED E,~BODIMENTS
_ Referring now to Fig. 1 there is shown a liquid electrographi development station 1 incorporating features of the present invention. Electrographic recording paper 2 is pulled through the development sta~ion 1 by passing through the nip of a pair af rollers 3 and 4~ Roller 4 is a squeegee roller having a compressible layer 5 on the outer surface thereof and such layer ~eing compressed against the other roller 3, as of stainless steel, to provide a frictional drive for the paper web 2 sand-wlched ~etween the two rollers 3 and 4. The squeegee roller 4 2Q' is driven in the clockwise direction via any one of a number of conventional drive means, such as a gear train or V-belt, not shDwn ~
The electrograp~ic recording paper 2 is threaded between an idler roller 5, as of stainless steel, and a development electrod roller 6, as of aluminum. Rollers 3 and 5 are positioned relativ to the development roller 6 so as to cause the electrographic recording web 2 to be pressed into nominal engagement with a portion of the surface of tlle developmcnt ~le~rOde 6. A V-belt power take of of ~he squeegee roller 4 is passed over an idler pulley 8 which in-turn drives the developmcllt roller 6 via a ///l ~///
11a 5C~8~:9 second V-bcIt ~Irivc ~. 'I'he pu]ley ratios are chosen so that t~.e peripheral spocd of the development electrode 6 is within the rangc of 2 to S times thc speed of the electrographic recording web 2 which is to be developed. Any one of a number of drive means, such as gear trains9 etc., ~.ay be employed as an alternati e to the V-belt drives 7 and 9.
Liquid electrographic toner is applied to the development drum via a spray pipe ll which directs a stream 12 of liquid toner against the outer cylindrical su~face 13 of the development electrode 6 in a region where the direction of movement of the development electrode 6 is toward the electrographic web 2 to be developed. The liquid electrographic toner comprises a dielectric liquid vehicle having a suspension of charged pigmented toner particles therein. The toner is drawn from a reservoir 14 and supplied to the spray pipe ll via a pump 15 and conduit 16. A spray shield 17 is interposed between the spray pipe 11 and the electrographic web 2 to prevent unwanted spraying of the electrographic toner directly OTltO the web 2.
The electrographic recording web 2 includes a conductive ` 20 paper backing having a dielectric insulative layer coated thereon `~ to form a charge retentive surface. Charge images to be developed are deposited upon the charge retentive surface and carried by the web 2 into the development station 1. The charge retentive layer is disposed -facing the development drum 6.
Rollers 3 and 5 make electrical contact to the conductive side of the web and the development electrode drum 6 may be operated at a floating potential relative to the potentials applicd to rollers 3 and 5 or the development drum 6 may be operated at a suitable development potential relative to the potentials applie to rollers 3 and S.
Referring now to ~i~. 2 there is shown the surface detail of the dcvclopmcnt electrode drum 6. The outer surface l3 o~ the .' ', ' ', . ~ . ' ' . ' ' . ' ' . . ' ~ .
~508~g drum 6 is rough, and in a prc~erre(l cmbodiment comprises an array of relatively thln longitudinally directed lands 21 separated by wider groove portions 22. In a typical example, the~ lands 21 have a height of approximately 0.050 :inch relative to the bottom of the groove portions 22. In operat:ion, the land portions 21 serve as wipers for wiping the depleted boundary layer of toner from tlle charge retentive surface of the recording web 2.
The groove regions 22 between adjacent lands 21 serve to carry - fresh toner into contact with the charge images to be developed lQ.'. on th.e recording web 2.
In addition, the ~ottom surface of the grooves 22 serves the function of the development electrode, namely, to provide a conductive surface operating at a different potential than that of the ch.arge images to be developed so that the field lines will extend betwe'en` the' charge images and the adjacent surface of the development elec'trode 6. In this manner the electric fields in the electrograph.ic toner region between t~e development electrode : 6 and the charge retentive surface are relatively high to pedite transfer of toner particles from the electrographlc 20 . toner liquid to the charge images to be developed. In a ' preferred embodiment, the groove portions 22 are wikhin 0.100 inc or less of the charge image ~eing developed. The land regions 21 ;~ should be relatively narrow relative to the groove region 22 so that nominal contact is established between the upper surfaces of the lands 22 and the charge retentive surface so as to :` efficiently disrupt the.boundary layer of'depleted toner adjacent the web 2.
In addition, the lands 21 should have a slight pitch relative to the axis of revolution of the development electrode 6 so that the paper web 2, particularly in the case of a fan-fold l/l/
/tl/
~ Q5~D~ Z~
elcctrograpllic web, ~loes not get c~ught and torn by the more rapidly moving peripllcral surfacc of the ~leveloprnent electrode 6.
The spiral pitC]I o~ the lands is suff:icient iE the pitch has advanced by one angular land period over the length of the development electrode 6. Furthermore, the surface 13 of the development electrode should be free of surface detail which is invariant in the direction of rotation of the development electrod e to prevent streaking and patterning of the developed image.
As an alternative to a surface roughness detai:L consisting of lands and grooves, the surface of the development electrode may be roughened ~y sand ~lasting, photoetching, or knurling.
Generally speaking, the rough surface 13 should have surface detail thereon ~aving mean peak-to-peak amplitude variations of between q.005 and 0.100 inch.
In an alternative embodiment oE the present invention, the development electrode drive can be arranged for driving the develop~ent electrode in a direction counter to the direction ; of ~oYement of the electrograp~ic we~ 2O In such an embodiment, ~; the Y-belt ta~e of drive 7 is moved to the back up roller 3 so20: a~ to drive the development electrode 6 in the counter-clockwise I direction. In this latter embodiment, the spray pipe 12 is preferably moved to a region adjacent the first quadrant of the developmént electrode so that the electrographic toner is sprayed onto the roughened surface o-f the surface 13 of the drum in a region moving toward the charge retentive surface to be de~eloped.
Although the surface roughening feature of the developmen~
electrode is, in a preferred embodiment, applied to an imperforate development electrode drum 6 this is not a requirement. It may be also used to advantage with perforated ~/!/
,.;, , .. . . . . . .
., ~ . .
' ' ' ~ ' ' '~ . ' ':
: . . . .
~ 2 ~
or porous dcvcloplllcnt olcctrodc drums whcreirl thc electrograp}lic toner is pumpcd througll the pcr:forated wall of the dcvelopment drum into contact Wit]l the charge retentive surface of the record.ing medium to be dcveloped. In the case of the perforated development electrode drum, the lands function in ~he same manner as previously described wit.h regard to the embodiment of Fig. 1 wherein the lands 21 serve to disrupt the boundary layer of depleted toner adjacent the charge retentive sur~ace of the recording web 2.
The differential speed between the speed o~ the recording web 2 and that of the periphery of the development electrode 6 is preferably at least twice the speed of the web 2.
An advantage of the spray method of supplying liquid toner to the development electrode, as contrasted with the method of dip~ing the lower part of the rotating drum in :Liquid toner, is that the spray tends to scrub away depleted toner from the surface of the drum due to its turbulent impact with the drum.
//// .
///~
//~/
//ll ////
////
////
////
////
////
////
//// .
~ .
Claims (14)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a method of developing electrostatic latent charge images on charge retentive surfaces the steps of:
mounting an electrically conductive development electrode with a rough outer cylindrical surface thereof for rotation about its axis of revolution;
passing the charge retentive surface of a recording medium, bearing a latent charge image thereon to be developed, adjacent said rough surface of the cylindrical development electrode;
rotating said cylindrical development electrode with an angular velocity such that the rough surface of said development electrode is moving at a different speed than that of the charge retentive surfaces to be developed; and supplying liquid electrographic development toner, having electroscopic toner particles suspended in a dielectric liquid, to the rough surface of said development electrode so that the toner liquid is brought into contact with the charge images to be developed for developing same.
mounting an electrically conductive development electrode with a rough outer cylindrical surface thereof for rotation about its axis of revolution;
passing the charge retentive surface of a recording medium, bearing a latent charge image thereon to be developed, adjacent said rough surface of the cylindrical development electrode;
rotating said cylindrical development electrode with an angular velocity such that the rough surface of said development electrode is moving at a different speed than that of the charge retentive surfaces to be developed; and supplying liquid electrographic development toner, having electroscopic toner particles suspended in a dielectric liquid, to the rough surface of said development electrode so that the toner liquid is brought into contact with the charge images to be developed for developing same.
2. The method of Claim 1 wherein the step of supplying liquid development toner to the rough surface of the development electrode comprises the step of directing a stream of liquid development toner against the outer rough cylindrical surface of the development electrode.
3. The method of Claim 2 wherein the step of directing the stream of liquid development toner onto the rough surface of the development electrode comprises, directing the stream of liquid development toner onto the rough surface region of said development electrode which is moving toward the charge image bearing surface to be developed.
4. The method of Claim 1 wherein the step of passing the charge retentive surface to be developed adjacent the rough surface of the development electrode includes, passing the charge retentive surface within 0.100 inch or less of the rough surface of the development electrode.
5. In an apparatus for developing electrostatic images on a charge retentive surface:
development electrode means having a rough cylindrical surface comprising a plurality of discrete projecting surface portions, separated from one another by a plurality of recessive surface portions;
means for mounting said development electrode means for rotation about its axis of revolution;
means for passing the charge retentive surface of a recording medium, for bearing latent charge images thereon to be developed, adjacent said rough surface of said development electrode and contiguous with said projecting surface portions thereof;
means for rotating said development electrode means with an angular velocity such that said rough surface of said development electrode moves at a different speed than that of the adjacent charge retentive surface to be developed; and means for supplying liquid electrographic development toner, having electroscopic toner particles suspended in a dielectric liquid, to the rough surface of said development electrode so that the toner liquid is carried into contact with the charge images on the charge retentive surface to be developed for developing same, said liquid toner being carried within said recessive surface portions, said projecting surface portions serving to wipe liquid toner from said charge retentive surface, whereby said charge retentive surface undergoes a plurality of successive development operations, each of said operations being followed by a wiping operation.
development electrode means having a rough cylindrical surface comprising a plurality of discrete projecting surface portions, separated from one another by a plurality of recessive surface portions;
means for mounting said development electrode means for rotation about its axis of revolution;
means for passing the charge retentive surface of a recording medium, for bearing latent charge images thereon to be developed, adjacent said rough surface of said development electrode and contiguous with said projecting surface portions thereof;
means for rotating said development electrode means with an angular velocity such that said rough surface of said development electrode moves at a different speed than that of the adjacent charge retentive surface to be developed; and means for supplying liquid electrographic development toner, having electroscopic toner particles suspended in a dielectric liquid, to the rough surface of said development electrode so that the toner liquid is carried into contact with the charge images on the charge retentive surface to be developed for developing same, said liquid toner being carried within said recessive surface portions, said projecting surface portions serving to wipe liquid toner from said charge retentive surface, whereby said charge retentive surface undergoes a plurality of successive development operations, each of said operations being followed by a wiping operation.
6. The apparatus of Claim 5 wherein said means for supplying liquid toner to said rough surface of said development electrode comprises, means for directing a stream of liquid toner onto the outer rotating rough surface of said development electrode.
-11a-
-11a-
7. The apparatus of Claim 6 wherein said toner supplying means is disposed for directing the stream of liquid toner onto the rotating surface of said development electrode in a region thereof which is moving toward the charge image bearing surface to be developed.
8. The apparatus of Claim 5 wherein said rough surface of said development electrode is made of an electrically conductive material, and wherein said means for passing the charge retentive surface to be developed adjacent said rough surface of said development electrode includes means for passing said charge retentive surface within 0.100 inch of the rough surface of said development electrode.
9. The apparatus of Claim 5 wherein said rough surface of said development electrode comprises an array of elongated land regions separated by elongated groove regions, said land and groove regions being elongated in a direction transverse to the direction of rotation of said development electrode.
10. The apparatus of Claim 9 wherein said array of land and groove regions spiral about the axis of revolution of said development electrode.
11. The apparatus of Claim 9 wherein said groove regions are wider than the intervening land regions.
12. The apparatus of Claim 5 wherein said rough surface of said development electrode is free of surface detail which is invariant in the direction of rotation of said development electrode to prevent streaking of the developed image.
13. The apparatus of Claim 5 wherein said rough surface of said development electrode is essentially imperforate so that essentially all the liquid toner supplied to the charge retentive surface to be developed by said development electrode is carried thereto by the outside rough surface of said development electode.
14. The apparatus of Claim 5 wherein said rough surface of said development electrode has surface detail thereon having mean peak-to-peak amplitude variations of between 0.005 and 0.100 inch.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US478813A US3921580A (en) | 1974-06-12 | 1974-06-12 | Liquid development of electrostatic images |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1050829A true CA1050829A (en) | 1979-03-20 |
Family
ID=23901455
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA229,043A Expired CA1050829A (en) | 1974-06-12 | 1975-06-11 | Electrostatic image development using development electrode with rough surface |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US3921580A (en) |
| JP (1) | JPS609270B2 (en) |
| CA (1) | CA1050829A (en) |
| DE (1) | DE2526097A1 (en) |
| FR (1) | FR2274963A1 (en) |
| GB (1) | GB1512728A (en) |
Families Citing this family (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4127082A (en) * | 1975-09-26 | 1978-11-28 | Sharp Kabushiki Kaisha | Wiper roller for drying a wet sheet in a copying machine |
| JPS54345U (en) * | 1977-06-03 | 1979-01-05 | ||
| FR2432660A1 (en) * | 1978-08-01 | 1980-02-29 | Kelsey Hayes Co | Disc brake actuator cylinder - has piston seal ring housed in cylinder wall groove including bottom with portions parallel and inclined to wall |
| JPS5717043A (en) * | 1980-07-04 | 1982-01-28 | Hitachi Ltd | Power-on resetting circuit |
| US4357096A (en) * | 1981-03-06 | 1982-11-02 | Eastman Kodak Company | Dispersion supply apparatus for photoelectrophoretic migration imaging |
| JPS5848555A (en) * | 1981-09-18 | 1983-03-22 | Fujitsu Ltd | Pcm reproducing relay circuit |
| US4410260A (en) * | 1981-12-09 | 1983-10-18 | Coulter Systems Corporation | Toning apparatus and method |
| JPS5957522A (en) * | 1982-09-27 | 1984-04-03 | Fujitsu Ltd | Automatic initial reset circuit |
| JPS62187867A (en) * | 1985-11-04 | 1987-08-17 | ベンソン，インコ−ポレイテツド | Plotter toner station |
| US4949133A (en) * | 1988-11-16 | 1990-08-14 | Xerox Corporation | Apparatus for cleaning and moving a photoreceptor |
| US5557376A (en) * | 1989-05-15 | 1996-09-17 | Indigo N.V. | Color imaging system |
| US5585900A (en) * | 1989-05-15 | 1996-12-17 | Indigo N.V. | Developer for liquid toner imager |
| US5148222A (en) * | 1990-08-22 | 1992-09-15 | Spectrum Sciences B.V. | Liquid developer system |
| US5117263A (en) * | 1991-01-22 | 1992-05-26 | Spectrum Sciences B.V. | Liquid toner developer |
| US5400124A (en) * | 1992-11-16 | 1995-03-21 | Eastman Kodak Company | Development station having a roughened toning shell |
| US5701561A (en) * | 1995-09-26 | 1997-12-23 | Minnesota Mining And Manufacturing Company | Method and apparatus for applying liquid toner to a print medium using multiple toner applicators for each liquid toner |
| JPH11174851A (en) * | 1997-12-05 | 1999-07-02 | Ricoh Co Ltd | Developing device |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3245381A (en) * | 1961-04-19 | 1966-04-12 | Agfa Ag | Developing apparatus |
| FR1399233A (en) * | 1963-06-22 | 1965-05-14 | Kalle Ag | Method and device for developing electrostatic latent images |
| GB1183531A (en) * | 1966-04-25 | 1970-03-11 | Rank Xerox Ltd | Developing electrostatic images |
| US3367791A (en) * | 1966-07-11 | 1968-02-06 | Addressograph Multigraph | Liquid development of electrostatic images |
| US3356072A (en) * | 1966-10-12 | 1967-12-05 | Dennison Mfg Co | Apparatus for developing electrostatic images |
| US3744897A (en) * | 1969-05-02 | 1973-07-10 | Xerox Corp | Transparent electrode for electrophoretic imaging |
| US3667428A (en) * | 1969-07-01 | 1972-06-06 | Xerox Corp | Developing systems |
| JPS5124254B1 (en) * | 1970-12-30 | 1976-07-22 | ||
| US3712728A (en) * | 1971-01-06 | 1973-01-23 | Xerox Corp | Reversal development |
| GB1388023A (en) * | 1971-03-24 | 1975-03-19 | Ricoh Kk | Sheet processing arrangements |
| US3801315A (en) * | 1971-12-27 | 1974-04-02 | Xerox Corp | Gravure imaging system |
| US3817748A (en) * | 1972-01-28 | 1974-06-18 | Xerox Corp | Contrast control in electrostatic copying utilizing liquid development |
| US3816114A (en) * | 1972-03-03 | 1974-06-11 | Xerox Corp | Electro-photographic method |
| JPS4965226A (en) * | 1972-10-21 | 1974-06-25 |
-
1974
- 1974-06-12 US US478813A patent/US3921580A/en not_active Expired - Lifetime
-
1975
- 1975-06-11 CA CA229,043A patent/CA1050829A/en not_active Expired
- 1975-06-11 DE DE19752526097 patent/DE2526097A1/en not_active Ceased
- 1975-06-12 FR FR7518441A patent/FR2274963A1/en active Granted
- 1975-06-12 GB GB25232/75A patent/GB1512728A/en not_active Expired
- 1975-06-12 JP JP50070250A patent/JPS609270B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2274963B1 (en) | 1982-04-16 |
| US3921580A (en) | 1975-11-25 |
| GB1512728A (en) | 1978-06-01 |
| JPS5111448A (en) | 1976-01-29 |
| DE2526097A1 (en) | 1976-01-02 |
| JPS609270B2 (en) | 1985-03-08 |
| FR2274963A1 (en) | 1976-01-09 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1050829A (en) | Electrostatic image development using development electrode with rough surface | |
| US4425382A (en) | Developer carrier | |
| US4258115A (en) | Wet developing method using elastic roller for electrostatic image and a device therefor | |
| US3901188A (en) | Electrostatic liquid developing apparatus | |
| CA1116223A (en) | Multiple applicator roller toner station, multiple roller dryer station for page printing system | |
| US5157443A (en) | Moving belt liquid development method and device | |
| CA1178643A (en) | Process and apparatus for transferring developed electrostatic images to a carrier sheet, improved carrier sheet for use in the process and method of making the same | |
| US3816114A (en) | Electro-photographic method | |
| GB1267888A (en) | Method and apparatus for developing electrostatic latent images | |
| EP0935174A1 (en) | Wet electrophotographic device | |
| US3618567A (en) | Apparatus for developing latent electrographic images with liquid ink | |
| CA1173702A (en) | Method and apparatus for transferring developed electrostatic images to a carrier sheet | |
| US4245023A (en) | Method for the development of electrostatic charge images | |
| US4043658A (en) | Electrophotographic photosensitive member | |
| GB2041790A (en) | Liq. development of electrostatic images | |
| CA1132341A (en) | Magnetic brush device for developing electrostatic charge images | |
| JPH08123207A (en) | Wet image forming device | |
| US3952702A (en) | Electrophotographic liquid toner development apparatus | |
| US3687107A (en) | Printing system | |
| CN1109935C (en) | Extruding roller assembly for wet-type developing device for electronic photographic printing machine | |
| KR19990010085U (en) | Developing roller cleaning device for wet electrophotographic printer | |
| US3844652A (en) | Transfer printing apparatus of electrophotographic apparatus | |
| JPH0922194A (en) | Wet type developing device | |
| KR100243237B1 (en) | Development apparatus in electrographic printer | |
| KR100304615B1 (en) | Development apparatus of liquid electrophotographic printer |