CA1071395A - Xerographic developing system rolls having magnets of different widths - Google Patents
Xerographic developing system rolls having magnets of different widthsInfo
- Publication number
- CA1071395A CA1071395A CA313,621A CA313621A CA1071395A CA 1071395 A CA1071395 A CA 1071395A CA 313621 A CA313621 A CA 313621A CA 1071395 A CA1071395 A CA 1071395A
- Authority
- CA
- Canada
- Prior art keywords
- developer
- magnetic
- band
- rolls
- magnets
- 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
Abstract
XEROGRAPHIC DEVELOPING SYSTEM ROLLS
HAVING MAGNETS OF DIFFERENT WIDTHS
ABSTRACT OF THE DISCLOSURE
A xerographic developing system has rotating rolls in which stationary magnets of different axial widths are located. Magnetic developer is attracted to these rolls and the developer band width is controlled by the width of the magnets. The rolls may be transport rolls or developer rolls. When this concept is employed for transport rolls, a much larger sump capacity may be utilized since the developer band width can be controlled by varying the sizes of the magnets to keep the developer at the outer edges of the developer sump moving inwards to the developer zone. When this concept is employed for developer rolls, compensation is provided . or spreading of the developer band and thereby loss of developer when the developer band is transported from one development roll in a magnetic brush system to another development roll either directly or by an intermediary transport roller.
HAVING MAGNETS OF DIFFERENT WIDTHS
ABSTRACT OF THE DISCLOSURE
A xerographic developing system has rotating rolls in which stationary magnets of different axial widths are located. Magnetic developer is attracted to these rolls and the developer band width is controlled by the width of the magnets. The rolls may be transport rolls or developer rolls. When this concept is employed for transport rolls, a much larger sump capacity may be utilized since the developer band width can be controlled by varying the sizes of the magnets to keep the developer at the outer edges of the developer sump moving inwards to the developer zone. When this concept is employed for developer rolls, compensation is provided . or spreading of the developer band and thereby loss of developer when the developer band is transported from one development roll in a magnetic brush system to another development roll either directly or by an intermediary transport roller.
Description
This invention relates to magnetic deyeloper transport systems and magnetic brush development systems.
More specificaliy, this invention relates to a magnetic developer transport system which controls the developer band width during transport thereof.
One application of the invention is for magnetic developer transport systems for a cascade development system.
Another application of the invention is for a magnetic transport system for a magnetic brush developer system.
Still another application o~ ~he invention is for a transport assembly which transports developer from one magnetic brush developer roll to another magnetic brush developer roll.
It is usually desirable to have as much developer capacity as possible in a developer sump since the more capacity that a sump has, the less frequent that a copying machine must be serviced to replace old developer with new developer.
It is an object of this invention to provide a developer transport system which will permit the use of large capacity developer sumps.
A problem with a magnetic brush development system has been spreading of a toner band on the magne~ic brush when the developer is passed between a nip formed by the magnetic brush and a photoreceptive surface and . ' .
.
:
More specificaliy, this invention relates to a magnetic developer transport system which controls the developer band width during transport thereof.
One application of the invention is for magnetic developer transport systems for a cascade development system.
Another application of the invention is for a magnetic transport system for a magnetic brush developer system.
Still another application o~ ~he invention is for a transport assembly which transports developer from one magnetic brush developer roll to another magnetic brush developer roll.
It is usually desirable to have as much developer capacity as possible in a developer sump since the more capacity that a sump has, the less frequent that a copying machine must be serviced to replace old developer with new developer.
It is an object of this invention to provide a developer transport system which will permit the use of large capacity developer sumps.
A problem with a magnetic brush development system has been spreading of a toner band on the magne~ic brush when the developer is passed between a nip formed by the magnetic brush and a photoreceptive surface and . ' .
.
:
- 2 -:,, q'1~5 also be~ween the nip o~ a magnetic brush and a transport roll in a multi-roll developer brush system whereby some o~ the developer is forced out of the development zone and is there-fore no longer available for developing an image during that cycle.
It is anoth~r object of this invention to provide a multi-magnetic developer roll system with means which will allow for spreading of a developer band on a magnetic developer roll and on an intermediate transport roll and yet retain all of the developer and transport the same at a proper width to another magnetic developer brush so that .
all of the developer may be used for developing an image during that cycle.
Thus, in accordance with the present teachings, :. :
there is provided a system for transporting ferromagnetic~.
developer which comprises a movable developer support means which defines a path of movement for the developer with magnetic means disposed on the side of the support means opposite the developer for attracting to and holding the developer on the support means in a band having varying widths along the path.
More specifically, a development system is provided for an electrophotographic reproduction machine which has a photoconductive imaging surface, an endless rotatable non-magnetic member which member is juxtaposed to the surface, a sump for storing a supply of ferromagnetic developer and means for moving the developer from the sump to the portion from which it is applied to the surface. ~lagnetic means is provided on the side of the member opposite the surface with the magnetic means forming magnetic fields of effective lengths -along the direction of movement of the member which differs in the direction generally perpendicular to the direction of ..
: ~ 3 :~
1~:D7~395 movement of the member.
Other aspects of this invention will become apparent from the following description with reference to the drawings wherein:
Figure l i5 a schematic view of a xerographic copying system illustrating in particular a magnetic roll transport system;
Figure 2 is a view of the transport system of Figure l 1attened out to illustrate a developer transport path and -the relative width of magnetic members in the transport system;
Figure 3 is a view along section line 3-3 of Figure l; and Figure 4 is a view of a schematic brush developer system in which the concept of the invention is incorporated.
~ :
-3a-~, ~107~395 This invention relates to well-kno~n xerographic copier systems. Such systems utilize a pho~oconductive drum or belt having arranged around it an imaging station~
a developing station, a trans~er station, a fusing station, and a cleaning station, all of which are well-known to those s~illed in the art.
~ Referring to ~igure 1, there is illustrated - a development station which comprises a drum 10, having a photoconductive surface 11 thereon, a developer ;sump 12 ha~ing developer particles 14 therein,-a pair o~ rotatable c~lindrical transpor~ rolls 16 and 18, and : a development electrode 20. The term "de~eloper'' as used in this specification and in the claims refer to . either xerographic carrier particles hĂ vin~ ferromagnetic properties mixed with xerographic toner particles or -; xerographlc tonex particles per se having ferromagnetic . properties. Located within the transport roll 16 are a plurality of stationary circumfexentially arranged . permanent magnets 22, 24, 26 and 28 ~Yhich are fixed to the developer housing. :
. Located within the transport roll 18 are ` .
- stationary circumerentially arranged per~anent magnets . I:
, 30, 32 and 34. ~hese perman~nt ma~nets are in the form of b~rs which ~xtend generally parallel to the axis ~5 about which its respective tr~nsport roll rotates.
~:
~a~:~3ss Referring to Figure 2, the rolls 16 and 18 are depicted in a flattened out position to illustrate the developer band width during transport thereof. The rolls have also been partially cut away to show the relative lengths of the permanent magnets surrounded thereby. It can be seen that magne-ts 22 and 2~ are the longest and are the same length, magnet 26 is shorter, magnets 28 and 30 are the same length but shorter than magnet 26 and magnets 32 and 34 are the same length but shorter than magnets 28 and 30 and correspond to the development zone width.
The magnets are positioned in such a manner and are of such a strength relative to each other tha-t the developer particles will form a width corresponding to substantially the length of the magnet when the toner particles are transported by -their respective roller to a position adjacent to the particular magnet. This means that toner particles on transport roller 16 which are adjacent to the magnet 22 will have a band width equal to the length of the magnet 22 and as the roller carries that band into the field of magnet 24 the band will remain the same width. When the roller 16 carries the same developer band within the field of magnet 26 the band width will ~ -narrow to the len~th of magne-t 26 and then as the band is transported within the field of magnet 28 the band width will narrow to the length of the magnet 28. As the band is transported across the magnet 28 into the field of magnet 30, the band of toner parlicles will be attracted to the roller 18 from the roller 16 where the toner particles assu~ a band width on the roller 18 -5- ~ --::
~6~7~L3~
equivalent to the length of the magnet 30 which is the same length as magnet 28. Thereafter the roller 18 transpor-ts the same toner band to the field of magnet 32 wherein the toner band width narrows to the leng-th of magnet 32 and thereafter the toner particle layer is carried within the field of magnet 34 and remains the same width since magnet 34 is the same leng-th as magnet 32. The transport roller 18 con-tinues to rotate the band of developer out of the field of magnet 34 to a release point 35 whereby the developer is no longer held onto the roll 18 by the magnet 34 and then falls by centrifugal force and gravity into the space between the electrode 20 and the photoreceptor 10 whereby the developer will cascade over the photoconduc-tor surface 11 to develop an electrostatic latent image thereon.
Magnet 22 is positioned in such a manner that :
it will attract the residual magnetic developer to the roll 16 thereby acting as a pickoff magnet. Magnet 24 is positioned to attract additional developer to i the roll 16 from the developer sump while the remaining .
magnets are positioned for transporting the developer to the release point 35.
As the developer band decreases, the layer of toner at the edges of the band builds up to a thickness greater than the layer between the edges as shown in Figure 3. A scraper blade 36 is positioned adjacent the : roller 18 in such a manner to scrape off the excess developer from the edges whereby a uniform layer is carried ~o the release point 35. The edye layer which :
~C)7~39~
is scraped off by the scraper 36 falls back into the developer sump at a position which corresponds axially with the ends of the magnets 34. ~rom this i-t can be seen that developer whlch was picked up in an axial position which corresponds with the ends of the magnets 22 and 24 has now been moved inwardly to an axial position which corresponds with the developement zone width. Thus, this sys-tem keeps developer moving from the axial ends of the sump housing -to a position where it can be utilized in image developement.
In cascade development, it is known that developer is dumped onto the photoconductive sur~ace over a width that corresponds to the development zone but as the developer cascades downwards over the photo-conductive surface, the developer width expands beyondthe width of the developement zone thus requiring a sump which is wider than the developement zone. The developer which is located in the end of the housing, which corres ponds -to a dimension beyond the width of the development zone, must be mixed and kept moving into the development zone in order that the maximum capacity of the sump or ; ~
developer sump is utilized. It follows tha-t with the ;
system o~ this invention, it is possible to construct developer sumps which are much wider than development zones since one can construct and design the magnets to be of such lengths and strengths to narrow the ' developer band to the width of the development zone at - the release point. Wi-th this additional developer sump capacity J a copier may be operated for a much longer period of time without having ~o replenish developer.
. . . .
. .
7 1l3~S
Referring to Figure 4, there is illustrated a magnetic brush development system comprising a photo-conductor belt 100, a developer sump 102 containing magnetic developer particles 104 therein, transport S rolls 106,and 108, a first developmen-t roll 110 and an upper development roll 112, and a transport roll 114 which is located between the development rolls. Located within the transport roll 106 are permanent magnet bars 116, 118 and 120. Located wi-thin the transport : 10 roll 108 are permanent magnet bars 112, 124, and 126 and ~ -located within the developer roll 110 are stationary permanent magnet bars 128, 130 and 132. Stationary permanent magne-t bars 134, 136 and 138 are located ~:
within the transport roll 114 and stationary permanent magnet bars 140, 142 and 144 are located within the developer roll 112. A scraper member 146 is located : adjacent the developer roll 112 and a scraper member 148 is located adjacent the developer roll 110 to : scrape off excess developer on the respectivè rolls~
and direct the same back to the sump 102. The transport rolls 106 and 108 operate in the same manner as the rolls 16 and 18 in the embodimen-t of Figure 1. The magnet 116 ~ is positioned to attract developer from the sump the the : surface of the roll 106 and is of a length which is greater than the width of the development zone. Magnets 120, 122, 124 and 126 are progressively shorter than magnet 116 to narrow the developer band attracted to the roll 106 by the magnet 116 to a width equal to the : development zone which is the width of magnet bar lZ6.
~ 30 The developer band is transferred to the magnetic brush 1~71395 as it comes within the field of the magnet 128 and since the band has already been reduced to the develop-ment zone width, the magnets 128 and 130 may be of equal length.
As described previously, developer builds up at the ends of the developer band as it becomes narrowed and therefore the scraper 148 is utilized to scrape off the excess developer at the edges of the developer band which falls back into the developer sump.
When developer passes through a nip between two rolls such as between -the photoconductor 100 and developer roll 110, the developer roll 110 and transport roll 114, and the transport roll 114 and the development roll 112, the developer band widens whereby developer is forced either out of the development zone or off the ends of the developer rolls. In order to compensate for ~ ;-and prevent this from happening J the magnets 132 and 134 may be longer than the development zone width to keep the developer on the rolls. Magnets 136 and 138 may be decreasingly shorter in length than magnet 134 so when -the developer band is passed through the nip between the transport roll 114 and the developer roll 112 the developer band will spread to the width of the developer zone thus retaining all the developer for presentation ` 25 by the developer roll 112 to the latent image.
If transport roll 114 is utilized as a developer roll instead o~ a transport roll, the width of the magnets of each roll ~ould be adjusted to com-pensate for widening of the developer band as the band passes through the nip between the photoconductor 100 _g_ ': ' :~7~395 and the respective developer roll to avoid developer loss and thus retain all the developer f`or pre~entation to the latent image.
In summary, it can be seen that in accordance with the principles of this invention, the developer band width can be controlled by varying the sizes of the magnets to keep the developer at the outer edges of the developer sump moving inwards to the developer zone. It can ;
also be utilized to compensate for spreading of the developer band and thereby loss of developer when the developer band is transported from one development roll in a magnetic brush system to another developmen-t roll -either directly or by an intermediary transport roller.
It is obvious that the concept of this invention may be applied to continuous webs rather than the trans-port or developer rollers described.
It should be understood that to carry out ; the principles of the invention the magnets can be designed to be any length and adjacent magnets may either vary in length or be the same length depending on the results desired and the space available to obtain such results. The main criteria is to design the magnets in such a manner to shape the developer band wi~th in ac.ardanae ~ith de~ired results.
.
It is anoth~r object of this invention to provide a multi-magnetic developer roll system with means which will allow for spreading of a developer band on a magnetic developer roll and on an intermediate transport roll and yet retain all of the developer and transport the same at a proper width to another magnetic developer brush so that .
all of the developer may be used for developing an image during that cycle.
Thus, in accordance with the present teachings, :. :
there is provided a system for transporting ferromagnetic~.
developer which comprises a movable developer support means which defines a path of movement for the developer with magnetic means disposed on the side of the support means opposite the developer for attracting to and holding the developer on the support means in a band having varying widths along the path.
More specifically, a development system is provided for an electrophotographic reproduction machine which has a photoconductive imaging surface, an endless rotatable non-magnetic member which member is juxtaposed to the surface, a sump for storing a supply of ferromagnetic developer and means for moving the developer from the sump to the portion from which it is applied to the surface. ~lagnetic means is provided on the side of the member opposite the surface with the magnetic means forming magnetic fields of effective lengths -along the direction of movement of the member which differs in the direction generally perpendicular to the direction of ..
: ~ 3 :~
1~:D7~395 movement of the member.
Other aspects of this invention will become apparent from the following description with reference to the drawings wherein:
Figure l i5 a schematic view of a xerographic copying system illustrating in particular a magnetic roll transport system;
Figure 2 is a view of the transport system of Figure l 1attened out to illustrate a developer transport path and -the relative width of magnetic members in the transport system;
Figure 3 is a view along section line 3-3 of Figure l; and Figure 4 is a view of a schematic brush developer system in which the concept of the invention is incorporated.
~ :
-3a-~, ~107~395 This invention relates to well-kno~n xerographic copier systems. Such systems utilize a pho~oconductive drum or belt having arranged around it an imaging station~
a developing station, a trans~er station, a fusing station, and a cleaning station, all of which are well-known to those s~illed in the art.
~ Referring to ~igure 1, there is illustrated - a development station which comprises a drum 10, having a photoconductive surface 11 thereon, a developer ;sump 12 ha~ing developer particles 14 therein,-a pair o~ rotatable c~lindrical transpor~ rolls 16 and 18, and : a development electrode 20. The term "de~eloper'' as used in this specification and in the claims refer to . either xerographic carrier particles hĂ vin~ ferromagnetic properties mixed with xerographic toner particles or -; xerographlc tonex particles per se having ferromagnetic . properties. Located within the transport roll 16 are a plurality of stationary circumfexentially arranged . permanent magnets 22, 24, 26 and 28 ~Yhich are fixed to the developer housing. :
. Located within the transport roll 18 are ` .
- stationary circumerentially arranged per~anent magnets . I:
, 30, 32 and 34. ~hese perman~nt ma~nets are in the form of b~rs which ~xtend generally parallel to the axis ~5 about which its respective tr~nsport roll rotates.
~:
~a~:~3ss Referring to Figure 2, the rolls 16 and 18 are depicted in a flattened out position to illustrate the developer band width during transport thereof. The rolls have also been partially cut away to show the relative lengths of the permanent magnets surrounded thereby. It can be seen that magne-ts 22 and 2~ are the longest and are the same length, magnet 26 is shorter, magnets 28 and 30 are the same length but shorter than magnet 26 and magnets 32 and 34 are the same length but shorter than magnets 28 and 30 and correspond to the development zone width.
The magnets are positioned in such a manner and are of such a strength relative to each other tha-t the developer particles will form a width corresponding to substantially the length of the magnet when the toner particles are transported by -their respective roller to a position adjacent to the particular magnet. This means that toner particles on transport roller 16 which are adjacent to the magnet 22 will have a band width equal to the length of the magnet 22 and as the roller carries that band into the field of magnet 24 the band will remain the same width. When the roller 16 carries the same developer band within the field of magnet 26 the band width will ~ -narrow to the len~th of magne-t 26 and then as the band is transported within the field of magnet 28 the band width will narrow to the length of the magnet 28. As the band is transported across the magnet 28 into the field of magnet 30, the band of toner parlicles will be attracted to the roller 18 from the roller 16 where the toner particles assu~ a band width on the roller 18 -5- ~ --::
~6~7~L3~
equivalent to the length of the magnet 30 which is the same length as magnet 28. Thereafter the roller 18 transpor-ts the same toner band to the field of magnet 32 wherein the toner band width narrows to the leng-th of magnet 32 and thereafter the toner particle layer is carried within the field of magnet 34 and remains the same width since magnet 34 is the same leng-th as magnet 32. The transport roller 18 con-tinues to rotate the band of developer out of the field of magnet 34 to a release point 35 whereby the developer is no longer held onto the roll 18 by the magnet 34 and then falls by centrifugal force and gravity into the space between the electrode 20 and the photoreceptor 10 whereby the developer will cascade over the photoconduc-tor surface 11 to develop an electrostatic latent image thereon.
Magnet 22 is positioned in such a manner that :
it will attract the residual magnetic developer to the roll 16 thereby acting as a pickoff magnet. Magnet 24 is positioned to attract additional developer to i the roll 16 from the developer sump while the remaining .
magnets are positioned for transporting the developer to the release point 35.
As the developer band decreases, the layer of toner at the edges of the band builds up to a thickness greater than the layer between the edges as shown in Figure 3. A scraper blade 36 is positioned adjacent the : roller 18 in such a manner to scrape off the excess developer from the edges whereby a uniform layer is carried ~o the release point 35. The edye layer which :
~C)7~39~
is scraped off by the scraper 36 falls back into the developer sump at a position which corresponds axially with the ends of the magnets 34. ~rom this i-t can be seen that developer whlch was picked up in an axial position which corresponds with the ends of the magnets 22 and 24 has now been moved inwardly to an axial position which corresponds with the developement zone width. Thus, this sys-tem keeps developer moving from the axial ends of the sump housing -to a position where it can be utilized in image developement.
In cascade development, it is known that developer is dumped onto the photoconductive sur~ace over a width that corresponds to the development zone but as the developer cascades downwards over the photo-conductive surface, the developer width expands beyondthe width of the developement zone thus requiring a sump which is wider than the developement zone. The developer which is located in the end of the housing, which corres ponds -to a dimension beyond the width of the development zone, must be mixed and kept moving into the development zone in order that the maximum capacity of the sump or ; ~
developer sump is utilized. It follows tha-t with the ;
system o~ this invention, it is possible to construct developer sumps which are much wider than development zones since one can construct and design the magnets to be of such lengths and strengths to narrow the ' developer band to the width of the development zone at - the release point. Wi-th this additional developer sump capacity J a copier may be operated for a much longer period of time without having ~o replenish developer.
. . . .
. .
7 1l3~S
Referring to Figure 4, there is illustrated a magnetic brush development system comprising a photo-conductor belt 100, a developer sump 102 containing magnetic developer particles 104 therein, transport S rolls 106,and 108, a first developmen-t roll 110 and an upper development roll 112, and a transport roll 114 which is located between the development rolls. Located within the transport roll 106 are permanent magnet bars 116, 118 and 120. Located wi-thin the transport : 10 roll 108 are permanent magnet bars 112, 124, and 126 and ~ -located within the developer roll 110 are stationary permanent magnet bars 128, 130 and 132. Stationary permanent magne-t bars 134, 136 and 138 are located ~:
within the transport roll 114 and stationary permanent magnet bars 140, 142 and 144 are located within the developer roll 112. A scraper member 146 is located : adjacent the developer roll 112 and a scraper member 148 is located adjacent the developer roll 110 to : scrape off excess developer on the respectivè rolls~
and direct the same back to the sump 102. The transport rolls 106 and 108 operate in the same manner as the rolls 16 and 18 in the embodimen-t of Figure 1. The magnet 116 ~ is positioned to attract developer from the sump the the : surface of the roll 106 and is of a length which is greater than the width of the development zone. Magnets 120, 122, 124 and 126 are progressively shorter than magnet 116 to narrow the developer band attracted to the roll 106 by the magnet 116 to a width equal to the : development zone which is the width of magnet bar lZ6.
~ 30 The developer band is transferred to the magnetic brush 1~71395 as it comes within the field of the magnet 128 and since the band has already been reduced to the develop-ment zone width, the magnets 128 and 130 may be of equal length.
As described previously, developer builds up at the ends of the developer band as it becomes narrowed and therefore the scraper 148 is utilized to scrape off the excess developer at the edges of the developer band which falls back into the developer sump.
When developer passes through a nip between two rolls such as between -the photoconductor 100 and developer roll 110, the developer roll 110 and transport roll 114, and the transport roll 114 and the development roll 112, the developer band widens whereby developer is forced either out of the development zone or off the ends of the developer rolls. In order to compensate for ~ ;-and prevent this from happening J the magnets 132 and 134 may be longer than the development zone width to keep the developer on the rolls. Magnets 136 and 138 may be decreasingly shorter in length than magnet 134 so when -the developer band is passed through the nip between the transport roll 114 and the developer roll 112 the developer band will spread to the width of the developer zone thus retaining all the developer for presentation ` 25 by the developer roll 112 to the latent image.
If transport roll 114 is utilized as a developer roll instead o~ a transport roll, the width of the magnets of each roll ~ould be adjusted to com-pensate for widening of the developer band as the band passes through the nip between the photoconductor 100 _g_ ': ' :~7~395 and the respective developer roll to avoid developer loss and thus retain all the developer f`or pre~entation to the latent image.
In summary, it can be seen that in accordance with the principles of this invention, the developer band width can be controlled by varying the sizes of the magnets to keep the developer at the outer edges of the developer sump moving inwards to the developer zone. It can ;
also be utilized to compensate for spreading of the developer band and thereby loss of developer when the developer band is transported from one development roll in a magnetic brush system to another developmen-t roll -either directly or by an intermediary transport roller.
It is obvious that the concept of this invention may be applied to continuous webs rather than the trans-port or developer rollers described.
It should be understood that to carry out ; the principles of the invention the magnets can be designed to be any length and adjacent magnets may either vary in length or be the same length depending on the results desired and the space available to obtain such results. The main criteria is to design the magnets in such a manner to shape the developer band wi~th in ac.ardanae ~ith de~ired results.
.
Claims (8)
1. A system for transporting ferromagnetic developer comprising movable developer support means for defining a path of movement of said developer, and magnetic means disposed on the side of said support means opposite said developer for attracting to and holding developer on said support means in a band having varying widths along said path.
2. The combination recited in Claim 1 wherein said support means comprises an endless member mounted for rotation about a fixed axis,
3. The combination recited in Claim 2 wherein said magnetic means is stationary and enclosed within said member.
4. The combination recited in Claim 3 wherein said magnetic means comprises permanent magnets for generating mag-netic fields which intersect said support means, said fields having different axial effect on said developer.
5. The combination recited in Claim 1 wherein the width of said band decreases in the direction of movement of said support means.
6. The combination recited in Claim 1 wherein the width of said band increases in the direction of movement of said support means.
7. The combination recited in Claim 1 wherein said support means comprises a plurality of endless members adjacent each other and said magnetic means comprises permanent magnets enclosed within said members.
8. A development system for an electrophotographic reproduction machine having a photoconductive imaging surface, an endless rotatable non-magnetic member, a portion of said member juxtaposed to said surface, a sump for storing a supply of ferromagnetic developer and means for moving said developer from said sump to said portion from which it is applied to said surface, magnetic means on the side of said member opposite said surface, the magnetic means forming magnetic fields of effective length along the direction of movement of said member which differ in a direction generally perpendicular to the direction of movement of said member.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA313,621A CA1071395A (en) | 1973-04-26 | 1978-10-17 | Xerographic developing system rolls having magnets of different widths |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US35459873A | 1973-04-26 | 1973-04-26 | |
| CA74197870A CA1048259A (en) | 1973-04-26 | 1974-04-19 | Xerographic developing system rolls having magnets of different widths |
| CA313,621A CA1071395A (en) | 1973-04-26 | 1978-10-17 | Xerographic developing system rolls having magnets of different widths |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1071395A true CA1071395A (en) | 1980-02-12 |
Family
ID=27163432
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA313,621A Expired CA1071395A (en) | 1973-04-26 | 1978-10-17 | Xerographic developing system rolls having magnets of different widths |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1071395A (en) |
-
1978
- 1978-10-17 CA CA313,621A patent/CA1071395A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |