CA1043851A - Cleaning material from a support surface - Google Patents
Cleaning material from a support surfaceInfo
- Publication number
- CA1043851A CA1043851A CA201,444A CA201444A CA1043851A CA 1043851 A CA1043851 A CA 1043851A CA 201444 A CA201444 A CA 201444A CA 1043851 A CA1043851 A CA 1043851A
- Authority
- CA
- Canada
- Prior art keywords
- blade
- drum
- support surface
- blades
- 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
- G03G21/0088—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge removing liquid developer
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Cleaning In Electrography (AREA)
Abstract
CLEANING MATERIAL FROM A SUPPORT SURFACE
Abstract of the Disclosure An electrostatographic reproduction apparatus has a movable support surface and includes cleaning means com-prising two scraper blades and mounting means for supporting these blades in engagement with the support surface, one blade being located downstream of the other. The second blade acts to clean material from the support surface and which has passed between the first blade and the support surface.
Abstract of the Disclosure An electrostatographic reproduction apparatus has a movable support surface and includes cleaning means com-prising two scraper blades and mounting means for supporting these blades in engagement with the support surface, one blade being located downstream of the other. The second blade acts to clean material from the support surface and which has passed between the first blade and the support surface.
Description
This invention relates to cleaning material from a support surface.
U.S. Patent Specification 3,660,863 discloses a single scraper blade for cleaning particulate toner material from a xerographic drum. A scraper blade is defined for the purposes of this specification as one ~;
whose stem extends towards the tip in the upstream direc-tion of the drum's movement and when pressed against the ; -drum exerts a chiselling action on the material on the drum surface. A wiper blade is defined for the purposes of this specification as one whose stem extends in the downstream direction of the drum motion. ~`
According to the present invention there is provided in or for electrostatographic reproduction apparatus having a movable support surface, means for forming a latent electrostatic image on said surface, means for `
presenting liquid developer to said latent image to develop the image, means to transfer the developed image to a sheet of support material and cleaning means to clean material remaining on the support surface after transfer, and a drive mechanism to move the support surface past said means in succession, the cleaning means comprising at least two scraper blades and mounting means for supporting said blades in engagement with said support surface, one blade being located downstream of the other, said mounting means further `
comprising a single mounting block for supporting said at least two scraper blades in engagement with said surface for cleaning liquid developer from said surface. The ` -second blade acts to clean material from the support surface which has passed between the first blade and the surface.
An example of the invention will now be described -with reference to the accompanying drawings in which;
r ~ 3 ~ ~ 1 Figure 1 shows a typical example of electrostato-graphic reproduction apparatus, Figure 2 shows a modified version of the apparatus of Figure 1 and :
Figure 3 shows a cleaning blade according to the invention which can replace the blade 21 of Figures 1 and 2 ~ -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 passed a -number of processing stations. The copying cycle starts j;
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 liquld developer is applied from a reservoir 15 by means of rolls 13 and 14. The roll 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 blade 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 electrostatic 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 3 ~
f . ..... ~ :. .
.~4~ L
with the drum and is pressed against the drum surface by a transfer roll 17 so that the developed image is transferred -to the paper which is then conveyed away from the transfer station through a chute (not shown). Any material remaining on the drum after the 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 scraper 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 success-fully 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 combinations of 4 ; :
., . .,::..
-, . .- .. - ... ........ . . . ~ .
:~43~5~
blades, liquids and drum surfaces), 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 cen-timetre. 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 fibres reaches the wiper blade 23 first. The ~' '' ..
characteristics of the w~per 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 forming 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 -20 deformation of the photoconductive material. When this ~' movement takes place, the bead present at the end surface will be left on the drum surface 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 the preceding rest period.
In order to overcome this problem, the programmer ..
~ t~ S 1 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 begins. 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 upstream 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.
. . . .
In the embodiment of Figure 1, it is possible to ;
omit the wiper blade if the sump extends from below the scraper blade towards the bottom dead centre of the drum.
The bead formed at the end of the scraper blade will then drop into the sump directly or flow down the drum surface until it eventually drops from the surface. The sump x may extend all the way to the bottom dead centre of the ;
drum if the paper conveyor apparatus can be suitably arranged, or it may be acceptable for any drops from the lowest region of the drum to be lost in the apparatus, the sump extending only partially towards bottom dead centre. There will be very few such drops, because when the drum is in motion, the upward movement of the drum surface will oppose the downward flow of the drops, and they will tend to drop from the surface before they reach bottom dead centre. Only when the drum is stationary will the drops flow further down the drum and such drops ;
are only supplied with the small amount of material from the bead present at the scraper blade and ink on the portion of the drum surface between the blade and the developer station when the drum stops. ~
:: ~. ''.
5 ~
~0 In Figure 1, the drum is arranged with the transfer station at the bottom of the drum and the cleaning station E acting on the upwardly moving surface of the drum. Figure 2 shows an alternative arrangement with the transfer station at the top of the drum, and the cleaning station acting on the downwardly moving surface of the drum. In this arrangement there is no wiper blade but instead a blade 23a similar in construction to the wiper blade of Figure 1 is mounted below the two scraper blades in approximately the same orientation as the scraper blades relative to the drum. The blade 23a is only lightly pressed on to the drum surface and serves to deflect any droplets on the drum surface into the sump.
Some droplets from the scraper blade pass over the upper surface of that blade and drip into the sump directly.
The material reaching the first scraper blade contains paper fibres which have been formed to be the main cause of blade failure - that is the blade ceases to remove all the material from the drum surface. The provision of two blades 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, ;
.:
Sl 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 ~-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 blade 21. The second part of the stem 33b, beyond the angle of the L, extends towards the drum but with a component directed downstream and is of the same material as the rest of the blade. A mounting block 34 supports the blade 31 by engaging the part 33b.
Any drops running down the drum surface from the downstream blade 22 pile up behind the scraper part of the blade (32 and 33a) until they overflow and are effectively "wiped" from the drum surface and guided to the sump by the part 33b.
. .
~ - . : .-.. . , .. ....... .. .... . . . . . ... . . . . . . . . . .
.. . . . .. .. . . . . . . . .
U.S. Patent Specification 3,660,863 discloses a single scraper blade for cleaning particulate toner material from a xerographic drum. A scraper blade is defined for the purposes of this specification as one ~;
whose stem extends towards the tip in the upstream direc-tion of the drum's movement and when pressed against the ; -drum exerts a chiselling action on the material on the drum surface. A wiper blade is defined for the purposes of this specification as one whose stem extends in the downstream direction of the drum motion. ~`
According to the present invention there is provided in or for electrostatographic reproduction apparatus having a movable support surface, means for forming a latent electrostatic image on said surface, means for `
presenting liquid developer to said latent image to develop the image, means to transfer the developed image to a sheet of support material and cleaning means to clean material remaining on the support surface after transfer, and a drive mechanism to move the support surface past said means in succession, the cleaning means comprising at least two scraper blades and mounting means for supporting said blades in engagement with said support surface, one blade being located downstream of the other, said mounting means further `
comprising a single mounting block for supporting said at least two scraper blades in engagement with said surface for cleaning liquid developer from said surface. The ` -second blade acts to clean material from the support surface which has passed between the first blade and the surface.
An example of the invention will now be described -with reference to the accompanying drawings in which;
r ~ 3 ~ ~ 1 Figure 1 shows a typical example of electrostato-graphic reproduction apparatus, Figure 2 shows a modified version of the apparatus of Figure 1 and :
Figure 3 shows a cleaning blade according to the invention which can replace the blade 21 of Figures 1 and 2 ~ -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 passed a -number of processing stations. The copying cycle starts j;
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 liquld developer is applied from a reservoir 15 by means of rolls 13 and 14. The roll 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 blade 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 electrostatic 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 3 ~
f . ..... ~ :. .
.~4~ L
with the drum and is pressed against the drum surface by a transfer roll 17 so that the developed image is transferred -to the paper which is then conveyed away from the transfer station through a chute (not shown). Any material remaining on the drum after the 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 scraper 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 success-fully 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 combinations of 4 ; :
., . .,::..
-, . .- .. - ... ........ . . . ~ .
:~43~5~
blades, liquids and drum surfaces), 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 cen-timetre. 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 fibres reaches the wiper blade 23 first. The ~' '' ..
characteristics of the w~per 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 forming 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 -20 deformation of the photoconductive material. When this ~' movement takes place, the bead present at the end surface will be left on the drum surface 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 the preceding rest period.
In order to overcome this problem, the programmer ..
~ t~ S 1 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 begins. 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 upstream 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.
. . . .
In the embodiment of Figure 1, it is possible to ;
omit the wiper blade if the sump extends from below the scraper blade towards the bottom dead centre of the drum.
The bead formed at the end of the scraper blade will then drop into the sump directly or flow down the drum surface until it eventually drops from the surface. The sump x may extend all the way to the bottom dead centre of the ;
drum if the paper conveyor apparatus can be suitably arranged, or it may be acceptable for any drops from the lowest region of the drum to be lost in the apparatus, the sump extending only partially towards bottom dead centre. There will be very few such drops, because when the drum is in motion, the upward movement of the drum surface will oppose the downward flow of the drops, and they will tend to drop from the surface before they reach bottom dead centre. Only when the drum is stationary will the drops flow further down the drum and such drops ;
are only supplied with the small amount of material from the bead present at the scraper blade and ink on the portion of the drum surface between the blade and the developer station when the drum stops. ~
:: ~. ''.
5 ~
~0 In Figure 1, the drum is arranged with the transfer station at the bottom of the drum and the cleaning station E acting on the upwardly moving surface of the drum. Figure 2 shows an alternative arrangement with the transfer station at the top of the drum, and the cleaning station acting on the downwardly moving surface of the drum. In this arrangement there is no wiper blade but instead a blade 23a similar in construction to the wiper blade of Figure 1 is mounted below the two scraper blades in approximately the same orientation as the scraper blades relative to the drum. The blade 23a is only lightly pressed on to the drum surface and serves to deflect any droplets on the drum surface into the sump.
Some droplets from the scraper blade pass over the upper surface of that blade and drip into the sump directly.
The material reaching the first scraper blade contains paper fibres which have been formed to be the main cause of blade failure - that is the blade ceases to remove all the material from the drum surface. The provision of two blades 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, ;
.:
Sl 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 ~-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 blade 21. The second part of the stem 33b, beyond the angle of the L, extends towards the drum but with a component directed downstream and is of the same material as the rest of the blade. A mounting block 34 supports the blade 31 by engaging the part 33b.
Any drops running down the drum surface from the downstream blade 22 pile up behind the scraper part of the blade (32 and 33a) until they overflow and are effectively "wiped" from the drum surface and guided to the sump by the part 33b.
. .
~ - . : .-.. . , .. ....... .. .... . . . . . ... . . . . . . . . . .
.. . . . .. .. . . . . . . . .
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In or for electrostatographic reproduction apparatus comprising a movable support surface, means for forming a latent electrostatic image on said surface, means for present-ing liquid developer to said latent image to develop the image, means to transfer the developed image to a sheet of support material and cleaning means to clean material remain-ing on the support surface after transfer, and a drive mechanism to move the support surface past said means in succession, the cleaning means comprising at least two scraper blades and mounting means for supporting said blades in engage-ment with said support surface, one blade being located down-stream of the other, said mounting means further comprising a single mounting block for supporting said at least two scraper blades in engagement with said surface for cleaning liquid developer from said surface.
2. Apparatus as claimed in claim 1 wherein the mounting means is adapted to move the blades out of engagement with said surface.
3. Apparatus as claimed in Claim 1 or Claim 2 wherein each blade is of polyurethane of below 95 Shore A hardness.
4. Apparatus as claimed in Claim 1 or Claim 2 wherein each blade has a rectangular longitudinal cross-section.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB3104373A GB1431309A (en) | 1973-06-29 | 1973-06-29 | Cleaning material from a support surface |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1043851A true CA1043851A (en) | 1978-12-05 |
Family
ID=10317098
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA201,444A Expired CA1043851A (en) | 1973-06-29 | 1974-06-03 | Cleaning material from a support surface |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA1043851A (en) |
| GB (1) | GB1431309A (en) |
| NL (1) | NL7408891A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2204276B (en) * | 1987-05-06 | 1991-04-17 | Xerox Corp | Fibre traps in copiers. |
-
1973
- 1973-06-29 GB GB3104373A patent/GB1431309A/en not_active Expired
-
1974
- 1974-06-03 CA CA201,444A patent/CA1043851A/en not_active Expired
- 1974-07-01 NL NL7408891A patent/NL7408891A/xx unknown
Also Published As
| Publication number | Publication date |
|---|---|
| GB1431309A (en) | 1976-04-07 |
| NL7408891A (en) | 1974-11-25 |
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