CA1043852A - Cleaning material from a support surface - Google Patents
Cleaning material from a support surfaceInfo
- Publication number
- CA1043852A CA1043852A CA201,783A CA201783A CA1043852A CA 1043852 A CA1043852 A CA 1043852A CA 201783 A CA201783 A CA 201783A CA 1043852 A CA1043852 A CA 1043852A
- Authority
- CA
- Canada
- Prior art keywords
- blade
- support surface
- scraper blade
- drum
- cleaning
- 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
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G21/00—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge
- G03G21/0005—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge for removing solid developer or debris from the electrographic recording medium
- G03G21/0011—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge for removing solid developer or debris from the electrographic recording medium using a blade; Details of cleaning blades, e.g. blade shape, layer forming
- G03G21/0017—Details relating to the internal structure or chemical composition of the blades
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Cleaning In Electrography (AREA)
Abstract
Abstract of the Disclosure When a scraper blade is used for cleaning liquid material from a support surface which moves uphill in operation, problems often are encountered in disposing of the liquid which is cleaned off from the surface. It may run back over the uncleaned part of the surface and drip off at random positions. To obviate this problem there is provided cleaning apparatus for cleaning material from an upwardly moving support surface. The cleaning apparatus includes a scraper blade adapted to engage the support surface and a wiper blade acting on the support surface upstream of the scraper blade.
Description
:~.043~
This invention relates to cleaning material from -a support surface.
U.S. Patent Specification 3,660,863 discloses a scraper blade acting on a xerographic drum for removing particulate toner material from the drum. A scraper blade is defined for the purposes of this specification as one ;
whose stem extends towards the tip in the upstream direction of the drum's movement and when pressed against the drum exerts a chiselling action on the material on the drum surface. When such a blade is used for cleaning liquid material from a support surface which in operation moves uphill, problems are encountered in disposing of the cleaned . : .
off liquid from the surface. It may run back over the uncleaned part of the surface and drip off at random positions.
In accordance with one aspect of this invention ~ ;
there is provided electrostatographic reproduction apparatus comprising a movable image support surface having a portion moving in operation in an upward direction, means for forming a latent electrostatic image on said surface, means for developing the latent image with liquid developer, means for transferring the developed image onto a sheet of transfer material, a drive mechanism to move the support surface past ~ ;
said means in succession and cleaning apparatus for cleaning material from an upwardly moving support surface comprising a scraper blade adapted to engage the support surface and a wiper blade acting on the support surface upstream of the scraper blade.
An example of the invention will now be described ~ -with re~erence to the accompanying drawings in which:
Figure 1 shows a typical example of electrostato- -
This invention relates to cleaning material from -a support surface.
U.S. Patent Specification 3,660,863 discloses a scraper blade acting on a xerographic drum for removing particulate toner material from the drum. A scraper blade is defined for the purposes of this specification as one ;
whose stem extends towards the tip in the upstream direction of the drum's movement and when pressed against the drum exerts a chiselling action on the material on the drum surface. When such a blade is used for cleaning liquid material from a support surface which in operation moves uphill, problems are encountered in disposing of the cleaned . : .
off liquid from the surface. It may run back over the uncleaned part of the surface and drip off at random positions.
In accordance with one aspect of this invention ~ ;
there is provided electrostatographic reproduction apparatus comprising a movable image support surface having a portion moving in operation in an upward direction, means for forming a latent electrostatic image on said surface, means for developing the latent image with liquid developer, means for transferring the developed image onto a sheet of transfer material, a drive mechanism to move the support surface past ~ ;
said means in succession and cleaning apparatus for cleaning material from an upwardly moving support surface comprising a scraper blade adapted to engage the support surface and a wiper blade acting on the support surface upstream of the scraper blade.
An example of the invention will now be described ~ -with re~erence to the accompanying drawings in which:
Figure 1 shows a typical example of electrostato- -
-2-. ' graphic reproduction apparatus, and Figure 2 shows a cleaning blade which can be substituted in the apparatus of Figure 1.
-3-.. .. . . . ~ . . . ,. .. . . .. , ,- .. - , ~3~
In the copying apparatus illustrated in Figure 1, ~
a copying drum 11 having a photoconductive surface is rotated -in the direction of the arrow about its axis past a number of processing stations. The copying cycle starts at the charging ;
station A wherein a corona discharge device 12 is energised to a high potential to apply charge to the drum surface. The drum then passes to the exposure station B at which a flowing -image of a document is projected on to the charged drum surface by an optical system not shown to produce an electrostatic latent image. The image flows so that it moves in synchronism with the moving drum surface. The latent image passes to the development station C at which liquid developer is applied from a reservoir 15 by means of rolls 13 and 14. The ~oll 13 is a supply roll whose lower portion dips into the liquid in the reservoir 15 and whose upper portion is spaced by (for example) 0.25 mm from the upper roll 14 which has its surface shaped with a helical groove. The roll 14 is provided with a flexible doctor 16 which removes liquid from the groove to below the groove upper edges due to the deformation of the blade into the groove. The developer is attracted by electro-static attraction from the remote part of the groove to the latent image across the gap between them to develop the image.
A sheet of paper is fed to a transfer station D by sheet feed apparatus not shown to move in synchronism with the drum and is pressed against the drum surface by a transfer roll 17 so that the developed image is transferred to t~e paper which is then conveyed away from the transfer station through a chute (not shown). Any material remaining on the drum after the ~3~5~
transfer station must now be cleaned off at the cleaning station E, to be described in greater detail. After cleaning, an electroluminescent strip 18 floods the drum surface with light to discharge any remaining charges, so that the drum can pass onto the charging station for the beginning of the next cycle.
At the cleaning station, there are provided two scraper blades 21 and 22 and a wiper blade 23. The scrap-er blades are mounted on a supporting block 24 with which they can be moved away from the drum 11 when the blades are not in use. If the blades are left pressing hard against a stationary drum, the photoconductive surface may be deformed ~
.. . ~ . .
and the blades may acquire a permanent set. A sump 25 is ;
located below the scraper blades to catch the liquid from the blades and the wiper blade 23 is mounted on the edge of the sump. ;
Each scraper blade is of polyurethane of 65 Shore A quality (90 Shore A is the hardest quality so far successfully tried) about 3/4 inch long and 80 thousandths of -an inch thick. The blade is clamped in a supporting block 24 over about the first third of its length. The end of the blade is at 90 to the length of the blade so as to form a cutting edge from surfaces at 90. A much smaller angle (such as 60) ~-at the cutting edge leads to failure by the edge becoming tucked under the blade by friction. The holder of the blade extends at 25 - 5 to the tangent to the drum at the point of contact (a wider variation of angle being possible to suit ;
different combirlations of blades, liquids and drum surfaces), '. '' . ..
.''.:' 1(~43;~
the blade being slightly flexed against the drum in operation by the supporting block 24, with a force of the order of 10 grams per centimetre. The wiper blade 23 is a 125~ m blade, for example of polyethylene terephthalate, only very lightly flexed against the drum surface.
The developer liquid remaining on the drum after the transfer station D, together with any foreign matter such as paper ibres reaches the wiper blade 23 first. The char-acteristics of the wiper blade 23 are such that most of the material passes under the blade unaffected. The scraper blades 21 and 22 then scrape the material from the drum 11 frming a bead at the end surface of each blade. When this bead reaches a certain size, it will fall into the sump or flow down the surface of the drum to the wiper blade 23 which then deflects the flowing material into the sump 25. ;~
; ::..: .
As mentioned above, the scraper blades are moved away from the drum surface at the beginning of a rest period when the drum is stationary so as to prevent deformation of the photoconductive material. When this movement takes place, the bead present at the end surface will be left on the drum sur-face and will tend to spread out on that surface. When the scraper blades are moved back into operative position, some of the bead material will have spread to downstream (upwards in Figure 1) of the final scraper blade and this material will then contaminate the succeeding processing stations.
This contamination is evidenced by a black line or strip on the first copy produced in a new copy run, formed by developer which has spread under the scraper blade during ~ ~.~- - . . .. . . . . . .
~()43i~
the preceding rest period.
In order to overcome this problem, the programmer which controls the operation of the processing stations and the drive to the drum is arranged to cause the drum to reverse a short distance with the blades still in contact before the rest period beings. The blades are thereby wiped of excess ink and trapped fibres and dust are released. The spread of the bead during the rest period is thus located totally up- - ;
stream of the scraper blade so that when the blade is engaged with the drum surface again and rotation of the drum resumed, the whole original bead will be scraped off the drum surface. ~ -A reverse motion of 7 to 9 mm has been found sufficient.
The material reaching the first scraper blade con-tains paper fibres which have been found to be the main cause of blade failure - that is the blade leaves an unacceptable amount of material on the drum surface. The provision of two blades, as in Figure 1, reduces the failure rate of the cleaning station, since the second blade is likely to remove -what the first blade may miss. The paper fibres have been `
found to be retained by the first blade, even if they may ;
cause that blade to let some ink past at the points where the ~ .. ...
fibres are engaged, so that few paper fibres reach the second blade to cause that blade to fail.
Figure 3 shows a cleaning blade 31 which has both .
scraping and wiping actions. The stem of the blade is L- -shaped, the first part 33a near the tip 32 extending towards -the drum with a component directed upstream and these parts of the blade act as a scraper and are formed similarly to the ;
. "... ..
~a43~
blade 21. The second part of the stem 33b, beyond the angle of the L, extends towards the drum but with a component dir-ected downstream and is of the same material as the rest of the blade. A mounting block 34 supports the blade 31 by en-gaging the part 33b. Any drops running down the drum surface from downstream blade 22 pile up behind the scraper part of the blade (32 and 33~ until they overflow and are effectively "wiped" from the drum surface and guided to the sump by the ::
part 33b.
.. - - , :: ~ .- .- - . . . . . . .
In the copying apparatus illustrated in Figure 1, ~
a copying drum 11 having a photoconductive surface is rotated -in the direction of the arrow about its axis past a number of processing stations. The copying cycle starts at the charging ;
station A wherein a corona discharge device 12 is energised to a high potential to apply charge to the drum surface. The drum then passes to the exposure station B at which a flowing -image of a document is projected on to the charged drum surface by an optical system not shown to produce an electrostatic latent image. The image flows so that it moves in synchronism with the moving drum surface. The latent image passes to the development station C at which liquid developer is applied from a reservoir 15 by means of rolls 13 and 14. The ~oll 13 is a supply roll whose lower portion dips into the liquid in the reservoir 15 and whose upper portion is spaced by (for example) 0.25 mm from the upper roll 14 which has its surface shaped with a helical groove. The roll 14 is provided with a flexible doctor 16 which removes liquid from the groove to below the groove upper edges due to the deformation of the blade into the groove. The developer is attracted by electro-static attraction from the remote part of the groove to the latent image across the gap between them to develop the image.
A sheet of paper is fed to a transfer station D by sheet feed apparatus not shown to move in synchronism with the drum and is pressed against the drum surface by a transfer roll 17 so that the developed image is transferred to t~e paper which is then conveyed away from the transfer station through a chute (not shown). Any material remaining on the drum after the ~3~5~
transfer station must now be cleaned off at the cleaning station E, to be described in greater detail. After cleaning, an electroluminescent strip 18 floods the drum surface with light to discharge any remaining charges, so that the drum can pass onto the charging station for the beginning of the next cycle.
At the cleaning station, there are provided two scraper blades 21 and 22 and a wiper blade 23. The scrap-er blades are mounted on a supporting block 24 with which they can be moved away from the drum 11 when the blades are not in use. If the blades are left pressing hard against a stationary drum, the photoconductive surface may be deformed ~
.. . ~ . .
and the blades may acquire a permanent set. A sump 25 is ;
located below the scraper blades to catch the liquid from the blades and the wiper blade 23 is mounted on the edge of the sump. ;
Each scraper blade is of polyurethane of 65 Shore A quality (90 Shore A is the hardest quality so far successfully tried) about 3/4 inch long and 80 thousandths of -an inch thick. The blade is clamped in a supporting block 24 over about the first third of its length. The end of the blade is at 90 to the length of the blade so as to form a cutting edge from surfaces at 90. A much smaller angle (such as 60) ~-at the cutting edge leads to failure by the edge becoming tucked under the blade by friction. The holder of the blade extends at 25 - 5 to the tangent to the drum at the point of contact (a wider variation of angle being possible to suit ;
different combirlations of blades, liquids and drum surfaces), '. '' . ..
.''.:' 1(~43;~
the blade being slightly flexed against the drum in operation by the supporting block 24, with a force of the order of 10 grams per centimetre. The wiper blade 23 is a 125~ m blade, for example of polyethylene terephthalate, only very lightly flexed against the drum surface.
The developer liquid remaining on the drum after the transfer station D, together with any foreign matter such as paper ibres reaches the wiper blade 23 first. The char-acteristics of the wiper blade 23 are such that most of the material passes under the blade unaffected. The scraper blades 21 and 22 then scrape the material from the drum 11 frming a bead at the end surface of each blade. When this bead reaches a certain size, it will fall into the sump or flow down the surface of the drum to the wiper blade 23 which then deflects the flowing material into the sump 25. ;~
; ::..: .
As mentioned above, the scraper blades are moved away from the drum surface at the beginning of a rest period when the drum is stationary so as to prevent deformation of the photoconductive material. When this movement takes place, the bead present at the end surface will be left on the drum sur-face and will tend to spread out on that surface. When the scraper blades are moved back into operative position, some of the bead material will have spread to downstream (upwards in Figure 1) of the final scraper blade and this material will then contaminate the succeeding processing stations.
This contamination is evidenced by a black line or strip on the first copy produced in a new copy run, formed by developer which has spread under the scraper blade during ~ ~.~- - . . .. . . . . . .
~()43i~
the preceding rest period.
In order to overcome this problem, the programmer which controls the operation of the processing stations and the drive to the drum is arranged to cause the drum to reverse a short distance with the blades still in contact before the rest period beings. The blades are thereby wiped of excess ink and trapped fibres and dust are released. The spread of the bead during the rest period is thus located totally up- - ;
stream of the scraper blade so that when the blade is engaged with the drum surface again and rotation of the drum resumed, the whole original bead will be scraped off the drum surface. ~ -A reverse motion of 7 to 9 mm has been found sufficient.
The material reaching the first scraper blade con-tains paper fibres which have been found to be the main cause of blade failure - that is the blade leaves an unacceptable amount of material on the drum surface. The provision of two blades, as in Figure 1, reduces the failure rate of the cleaning station, since the second blade is likely to remove -what the first blade may miss. The paper fibres have been `
found to be retained by the first blade, even if they may ;
cause that blade to let some ink past at the points where the ~ .. ...
fibres are engaged, so that few paper fibres reach the second blade to cause that blade to fail.
Figure 3 shows a cleaning blade 31 which has both .
scraping and wiping actions. The stem of the blade is L- -shaped, the first part 33a near the tip 32 extending towards -the drum with a component directed upstream and these parts of the blade act as a scraper and are formed similarly to the ;
. "... ..
~a43~
blade 21. The second part of the stem 33b, beyond the angle of the L, extends towards the drum but with a component dir-ected downstream and is of the same material as the rest of the blade. A mounting block 34 supports the blade 31 by en-gaging the part 33b. Any drops running down the drum surface from downstream blade 22 pile up behind the scraper part of the blade (32 and 33~ until they overflow and are effectively "wiped" from the drum surface and guided to the sump by the ::
part 33b.
.. - - , :: ~ .- .- - . . . . . . .
Claims (6)
1. Electrostatographic reproduction apparatus comprising a movable image support surface having a portion moving in operation in an upward direction, means for forming a latent electrostatic image on said surface, means for developing the latent image with liquid developer, means for transferring the developed image onto a sheet of transfer material, a drive mechanism to move the support surface past said means in succession and cleaning apparatus for cleaning material from an upwardly moving support surface comprising a scraper blade adapted to engage the support surface and a wiper blade acting on the support surface upstream of the scraper blade.
2. Apparatus as claimed in claim 1 wherein the scraper blade is of polyurethane of below 95 Shore A hardness.
3. Apparatus as claimed in claim 2 wherein the scraper blade is of rectangular longitudinal cross-section.
4. Apparatus as claimed in any one of claims 1, 2 or 3 comprising means to remove the scraper blade from said surface.
5. Apparatus as claimed in any one of claims 1, 2 or 3 comprising a sump located below the scraper blade, and positioned to receive material wiped from said surface by the wiper blade.
6. Apparatus as claimed in any one of claims 1, 2 or 3 comprising a sump located below the scraper blade, and positioned to receive material wiped from said surface by the wiper blade, and wherein the wiper blade is mounted on one edge of the sump.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB3104473A GB1438660A (en) | 1973-06-29 | 1973-06-29 | Cleaning material from a support surface |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1043852A true CA1043852A (en) | 1978-12-05 |
Family
ID=10317118
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA201,783A Expired CA1043852A (en) | 1973-06-29 | 1974-06-06 | Cleaning material from a support surface |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1043852A (en) |
| GB (1) | GB1438660A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59182487A (en) * | 1983-04-01 | 1984-10-17 | Mita Ind Co Ltd | Cleaning device of transfer type electrostatic copying machine |
-
1973
- 1973-06-29 GB GB3104473A patent/GB1438660A/en not_active Expired
-
1974
- 1974-06-06 CA CA201,783A patent/CA1043852A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1438660A (en) | 1976-06-09 |
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