CA1042654A - Toner recovery system - Google Patents
Toner recovery systemInfo
- Publication number
- CA1042654A CA1042654A CA213,223A CA213223A CA1042654A CA 1042654 A CA1042654 A CA 1042654A CA 213223 A CA213223 A CA 213223A CA 1042654 A CA1042654 A CA 1042654A
- Authority
- CA
- Canada
- Prior art keywords
- developer
- toner particles
- air
- printing machine
- housing
- 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
ABSTRACT OF THE DISCLOSURE
A portion of a xerographic development material is slowly circulated past a vertically oriented porous wall where it serves as a filter for airborne toner particles flowing therethrough. Toner enriched develop-ment material is returned to the main body of development material reuse. Toner particles cleaned form residual xerographic images are conveniently transported by airflow entrainment to the development material filter.
A portion of a xerographic development material is slowly circulated past a vertically oriented porous wall where it serves as a filter for airborne toner particles flowing therethrough. Toner enriched develop-ment material is returned to the main body of development material reuse. Toner particles cleaned form residual xerographic images are conveniently transported by airflow entrainment to the development material filter.
Description
104'~654 U.S. Patent No. 3,982,043 issued on September 21, 1976 naming H.W.
Simpson as inventor and commonly ass;gned herewith, discloses a technique for filtering airborne electroscopic toner particles by the use of a body of relatively larger carrier beads whose surfaces react with the electro-scopic toner particles to develop substantial triboelectric charging there-between. When the filtering body becomes saturated with collected toner particles, it can be used as a xerographic development mixture.
Our invention implements this filter technique for use in an automatic xerographic printing machine such as an office copier. In accordance with our invention, a filter chamber is constructed of a pair of substantially vertically extending fine mesh or porous walls spaced to form a panel-like chamber of generally uniform thickness. A portion of the developer charge of the printing machine is lifted by suitable conveying means from a sump to the upper end of the filter chamber. A flow control gate at the lower end of the filter chamber is controlled to slowly return developer material ~from the lower end of the filter chamber to the sump. The development mate-rial thus slowly progresses downwardly between the porous side walls of the filter chamber and is returned for mixing with the main body of development material in the sump.
A;rborne toner particles are generally detremental to continued reli-able operation of a xerographic copy machine. The developer unit itself is a primary source of such toner particles. Our filter construction makes it practically feasible to apply a sub-atmospheric pressure to the developer unit housing to prevent escape of airborne toner particles from the housing to other areas of the copy machine. Air flow for maintaining the sub-atmos-pheric pressure within the developer housing passes through the mesh walls of the filter chamber and the body of development material contained there-between. Toner particles entrained in the air flow are triboelectrically captured by the carrier material of the developer mixture and eventually are returned with the development mixture to the sump for reuse.
The residual image cleaning station of a copy machine traditionally LE9-73-OOB 2 ~
~04'~654 1 has employed a rapidly moving brush that lifts toner particles into an air stream in a manner similar to a household vacuum cleaner. The toner particles traditionally have been captured by a fibrous bag-like filter which requires periodic replacement. Various proposals have been made for capturing cleaned toner and returning it to the developer station for reuse through various solids conveyor devices.
The disclosed invention can be broadly thought of as an improved xero-graphic printing machine. The printing machine has an imaging surface and an image development station which comprises a developer housing and means within the developer housing for conveying a developer mixture of relatively large carrier particles and relatively small toner particles into operative develop-ment relationship with a differential electrostatic charge image existing on the imaging surface. The improvement of this machine to which the disclosed invention is broadly directed comprises a body of the developer mixture which is supported within the developer housing. A source of subatmospheric air pressure is provided. A conduit means is connected between the subatmospheric air pressure source and the developer housing such that an air flow is esta-blished through the body of developer mixture whereby air suspended toner par-ticles within the developer housing are drawn into the air flow and through the body of developer mixture. This procedure then causes the air suspended toner particles to attach themselves to the carrier particles in the body of the developer mixture and are thereby separated from the air.
With use of a filter device constructed in accordance with our invention, in association with the developer unit of the copy machine, it becomes practi-cal to convey the toner laden air stream created in conjunction with a clean-ing brush directly to the developer unit thereby enabling the toner particles to be directly captured by the filtering body of developer material. Those skilled in the art will recognize that other sources of airborne toner par-ticles can be purged through use of our invention and the reasonably simple technique of providing an air conduit from the subatmospheric pressure deve-lopment chamber to the area to be purged.
These and other objects, features and advantages of our invention will 1 be apparent to those skilled in the art from the following more specific des-cription of an illustrative preferred embodiment thereof, wherein reference is made to the accompanying drawings of which:
FIGURE 1 is a front cross-sectional view of a copy machine having an improved airborne toner filter constructed in accordance with our invention, FIGURE 2 is a side elevation cross-sectional view of the machine shown in Figure 1 taken along line II-II thereof, and, FIGURE 3 is a fragmentary cross-sectional view of an alternate preferred embodiment of our invention.
Referring now more specifically to the drawings, Figure 1 shows a xero-graphic type copy printing machine 10 having a copy drum 11 that supports a photoconductive imaging surface 12 for movement successively past corona charging unit 13, optical imagewise discharging unit 14, physical toner image development unit 20, transfer corona 15 and residual image cleaning unit 60.
A large percent.age of the toner image 16 produced at development unit 20 is transferred to copy sheets 17 by the transfer corona 15, however, residual toner material 18 remains on the imaging surface 12 and must be cleaned prior to creation of a new and different image.
Development unit 20 is illustrated as employing a magnetic brush 20a like that disclosed in U.S. Patent 3,754,526 for bringing a development mixture 22 into operative developing relationship with a differential electrostatic charge latent image at the imaging surface 12. The material 22 comprises relatively large carrier beads 23 and relatively small toner particles 24 whose triboelec-tric relationship is such that substantial charge is developed upon mutual con-tact. It will be recognized that the filter technique of our invention is also adaptable to other development systems which employ a development mixture of triboelectrically opposite carrier and toner particles.
Development ùnit 20 includes a developer housing 21 that is formed to define a sùmp 25 where a primary mixture of development material 22 is main-tained. The sump 25 preferably includes one or more mixing devices such as auger 26 to maintain a uniform mixture of the developer material 22. A
lifting bucket conveyor 27 is mounted within the developer housing 21 for ~.~
10~'~654 1 circulating the developer material 22 from sump 25 to an elevated hopper 28 where ;t is applied to the magnetic development brush 20a and from there returned to the sump 25 by gravity where it is reenriched with toner par-ticles in the aforesaid mixing process.
A toner supply unit 29 constructed, for example, in accordance with U.S. Patent 3,572,555 adds toner material to the development mix in sump 25 as toner is depleted with the production of copies. The mechanism thus far described is merely illustrative of electrophotographic techniques well known to those skilled in the art.
In accordance with our invention we have provided an airborne toner filter unit 30 which is preferably formed as part of the developer housing 21. Filter unit 30 comprises a pair of vertically extending porous mesh walls 31 and 32 substantially uniformly spaced to form a panel-like auxil-liary filter chamber 34 that supports a body of the development material 22.
The chamber 34 is located vertically above the level of sump 25 and below the level of hopper 28. The porous walls 31 and 32 provide openings through which air and toner particles 24 can pass but which are substantially smaller than the carrier particles 23. An inlet chute or conduit 36 is connected between the hopper 28 and the upper end of chamber 34 for diverting a portion of the development material lifted by conveyor 27 into the filter chamber 34.
An outlet chute 38 is connected between the lower end of filter chamber 34 and the sump 25 for returning developer material to the sump 25. A flow control gate device 40 regulates the amount of material returned to sump 25.
One form of gate device is conveniently provided by a cylinder 42 that is closely confined by the adjacent walls of filter chamber 34 and contains a notch or cavity 44. Shaft 42 is driven slowly during rotation of drum 11 by a worm gear 46 and a pinion 48. Each revolution of shaft 42 thus returns the volume of notch 44 of developer material to the sump 25 and thereby allows an equal amount of developer material to enter the inlet chute 36.
To maintain a sub-atmospheric pressure within developer ~04Z6~4 1 housing 21, the vacuum end of a low speed blower 50 is
Simpson as inventor and commonly ass;gned herewith, discloses a technique for filtering airborne electroscopic toner particles by the use of a body of relatively larger carrier beads whose surfaces react with the electro-scopic toner particles to develop substantial triboelectric charging there-between. When the filtering body becomes saturated with collected toner particles, it can be used as a xerographic development mixture.
Our invention implements this filter technique for use in an automatic xerographic printing machine such as an office copier. In accordance with our invention, a filter chamber is constructed of a pair of substantially vertically extending fine mesh or porous walls spaced to form a panel-like chamber of generally uniform thickness. A portion of the developer charge of the printing machine is lifted by suitable conveying means from a sump to the upper end of the filter chamber. A flow control gate at the lower end of the filter chamber is controlled to slowly return developer material ~from the lower end of the filter chamber to the sump. The development mate-rial thus slowly progresses downwardly between the porous side walls of the filter chamber and is returned for mixing with the main body of development material in the sump.
A;rborne toner particles are generally detremental to continued reli-able operation of a xerographic copy machine. The developer unit itself is a primary source of such toner particles. Our filter construction makes it practically feasible to apply a sub-atmospheric pressure to the developer unit housing to prevent escape of airborne toner particles from the housing to other areas of the copy machine. Air flow for maintaining the sub-atmos-pheric pressure within the developer housing passes through the mesh walls of the filter chamber and the body of development material contained there-between. Toner particles entrained in the air flow are triboelectrically captured by the carrier material of the developer mixture and eventually are returned with the development mixture to the sump for reuse.
The residual image cleaning station of a copy machine traditionally LE9-73-OOB 2 ~
~04'~654 1 has employed a rapidly moving brush that lifts toner particles into an air stream in a manner similar to a household vacuum cleaner. The toner particles traditionally have been captured by a fibrous bag-like filter which requires periodic replacement. Various proposals have been made for capturing cleaned toner and returning it to the developer station for reuse through various solids conveyor devices.
The disclosed invention can be broadly thought of as an improved xero-graphic printing machine. The printing machine has an imaging surface and an image development station which comprises a developer housing and means within the developer housing for conveying a developer mixture of relatively large carrier particles and relatively small toner particles into operative develop-ment relationship with a differential electrostatic charge image existing on the imaging surface. The improvement of this machine to which the disclosed invention is broadly directed comprises a body of the developer mixture which is supported within the developer housing. A source of subatmospheric air pressure is provided. A conduit means is connected between the subatmospheric air pressure source and the developer housing such that an air flow is esta-blished through the body of developer mixture whereby air suspended toner par-ticles within the developer housing are drawn into the air flow and through the body of developer mixture. This procedure then causes the air suspended toner particles to attach themselves to the carrier particles in the body of the developer mixture and are thereby separated from the air.
With use of a filter device constructed in accordance with our invention, in association with the developer unit of the copy machine, it becomes practi-cal to convey the toner laden air stream created in conjunction with a clean-ing brush directly to the developer unit thereby enabling the toner particles to be directly captured by the filtering body of developer material. Those skilled in the art will recognize that other sources of airborne toner par-ticles can be purged through use of our invention and the reasonably simple technique of providing an air conduit from the subatmospheric pressure deve-lopment chamber to the area to be purged.
These and other objects, features and advantages of our invention will 1 be apparent to those skilled in the art from the following more specific des-cription of an illustrative preferred embodiment thereof, wherein reference is made to the accompanying drawings of which:
FIGURE 1 is a front cross-sectional view of a copy machine having an improved airborne toner filter constructed in accordance with our invention, FIGURE 2 is a side elevation cross-sectional view of the machine shown in Figure 1 taken along line II-II thereof, and, FIGURE 3 is a fragmentary cross-sectional view of an alternate preferred embodiment of our invention.
Referring now more specifically to the drawings, Figure 1 shows a xero-graphic type copy printing machine 10 having a copy drum 11 that supports a photoconductive imaging surface 12 for movement successively past corona charging unit 13, optical imagewise discharging unit 14, physical toner image development unit 20, transfer corona 15 and residual image cleaning unit 60.
A large percent.age of the toner image 16 produced at development unit 20 is transferred to copy sheets 17 by the transfer corona 15, however, residual toner material 18 remains on the imaging surface 12 and must be cleaned prior to creation of a new and different image.
Development unit 20 is illustrated as employing a magnetic brush 20a like that disclosed in U.S. Patent 3,754,526 for bringing a development mixture 22 into operative developing relationship with a differential electrostatic charge latent image at the imaging surface 12. The material 22 comprises relatively large carrier beads 23 and relatively small toner particles 24 whose triboelec-tric relationship is such that substantial charge is developed upon mutual con-tact. It will be recognized that the filter technique of our invention is also adaptable to other development systems which employ a development mixture of triboelectrically opposite carrier and toner particles.
Development ùnit 20 includes a developer housing 21 that is formed to define a sùmp 25 where a primary mixture of development material 22 is main-tained. The sump 25 preferably includes one or more mixing devices such as auger 26 to maintain a uniform mixture of the developer material 22. A
lifting bucket conveyor 27 is mounted within the developer housing 21 for ~.~
10~'~654 1 circulating the developer material 22 from sump 25 to an elevated hopper 28 where ;t is applied to the magnetic development brush 20a and from there returned to the sump 25 by gravity where it is reenriched with toner par-ticles in the aforesaid mixing process.
A toner supply unit 29 constructed, for example, in accordance with U.S. Patent 3,572,555 adds toner material to the development mix in sump 25 as toner is depleted with the production of copies. The mechanism thus far described is merely illustrative of electrophotographic techniques well known to those skilled in the art.
In accordance with our invention we have provided an airborne toner filter unit 30 which is preferably formed as part of the developer housing 21. Filter unit 30 comprises a pair of vertically extending porous mesh walls 31 and 32 substantially uniformly spaced to form a panel-like auxil-liary filter chamber 34 that supports a body of the development material 22.
The chamber 34 is located vertically above the level of sump 25 and below the level of hopper 28. The porous walls 31 and 32 provide openings through which air and toner particles 24 can pass but which are substantially smaller than the carrier particles 23. An inlet chute or conduit 36 is connected between the hopper 28 and the upper end of chamber 34 for diverting a portion of the development material lifted by conveyor 27 into the filter chamber 34.
An outlet chute 38 is connected between the lower end of filter chamber 34 and the sump 25 for returning developer material to the sump 25. A flow control gate device 40 regulates the amount of material returned to sump 25.
One form of gate device is conveniently provided by a cylinder 42 that is closely confined by the adjacent walls of filter chamber 34 and contains a notch or cavity 44. Shaft 42 is driven slowly during rotation of drum 11 by a worm gear 46 and a pinion 48. Each revolution of shaft 42 thus returns the volume of notch 44 of developer material to the sump 25 and thereby allows an equal amount of developer material to enter the inlet chute 36.
To maintain a sub-atmospheric pressure within developer ~04Z6~4 1 housing 21, the vacuum end of a low speed blower 50 is
2 connected by conduit 52 with the housing 21 downstream of
3 the filter chamber 34. An air flow path is thus establisned
4 from the interior of developer housing 21 which contains airborne toner particles 54 to the conduit 52 so that toner 6 laden air pulled from the developer housing 21 or elsewhere 7 passes through the filter chamber 34 before being discharged 8 by blower 50 into the atmosphere. It may be desirable to 9 employ a supplementary safety filter 56 downstream of filter chamber 34 to capture any toner particles 24 that might escape 11 filter 30. With developer housing 21 maintained at sub-atmos-12 pheric pressure it will be recognized that any air movement 13 through openings of the housing 21 such as those adjacent 14 imaging surface 12 will be into rather than out of the developer housing 21.
16 In operation, development material 22 is normally main-17 tained with a toner concentration that is substantially less 18 than the maximum concentration of which the carrier material 19 23 is capable. The portlon of the development material 22 that is diverted into filter chamber 34 is held in the path 21 of toner laden air flow 58. The substantially uniform thick-22 ness of the chamber 34 assures a substantially constant and 23 predictable air pressure drop accross the body of filter 24 material therein. As toner is captured by the carrier 23 within chamber 34 and the carrier thus approaches saturation, 26 it is moved progressively downwardly and eventually is 27 reintroduced into sump 25 where its captured toner is readily 28 mixed with the main body of development material 22. The 29 vertical orientation of walls 31 and 32 minimize the tendency for carrier beads to clog the openings in the mesh of walls 31 and 32. It will be recognized that this tendency could be 2 further minimized by a slight inclination of the walls 31 3 and 32 so that chamber 34 would widen slightly at its lower 4 end.
Cleaning unit 60 comprises a brush 61 in an enclosure 62 6 which can be constructed and operated like that described in 7 U. S. Patent 3,615,813. Brush 61 acts to dislodge particles 8 of the residual toner image 18 from imaging surface 12 and 9 carry them past a flicker bar 64 where they are ejected into an air s~ream created by a suitable vacuum source. Whereas 11 U. S. Patent 3,615,813 employs a replaceable filter bag in the 12 vacuum line, our .invention provides a return duct 66 connected 13 between cleaning unit .enclosure 62 and developer housing 21.
14 Blower 50 thus is placed in effective communication with cleaning unit enclosure 62 and develops the vacuum creating an 16 air flow to entrain airborne toner particles 68 flicked from 17 brush 61 and transport the entrained toner particles 68 into 18 developer .housing 21. Once in developer housing 21 the airborne 19 toner particles are further filtered as previously described by the body of developer material in filter chamber 34. It will 21 be recognized that our invention not only eliminates the need 22 for a cleaning station air filter but conveniently provides for 23 the recapture and reuse of toner material collected from the 24 residual image by the cleaning unit 60.
Figure 3 shows an alternate preferred embodiment where 26 only a lower portion of a developer housing 70 is illustrated.
27 Housing 70 supports a body of developer material 22, like that 28 described above, in a sump 71. The development material 22 is 29 transported past an electrostatic image on a copy drum (not shown) by conveyor 72. The body of development material 22 in 1 sump 71 is mixed and agitated by an auger 73. A porous wall 2 of screen mesh 74 contacts the body of de.velopment material 22 in a direction 75 between the horizontal and the nadir such 4 that carrier beads 23 are not held by gravity against the porous wall 74. A conduit 76 is connected to a suitable source 6 of sub-atmospheric pressure (not shown) to draw air from the 7 space 77 within the developer housing 70 through the body of 8 development material in sump 71 and the porous wall 74 which 9 forms the inlet to conduit 76. The development material 22 in the vicinity of porous wall 74 is continually moved during 11 operation by the action of conveyor 72 and mixing auger 73.
12 Those skilled in the art will recognize that various 13 modifications, additions and deletions can be made to the 14 preferred embodiment thus described. For example, while for compactness and simplicity we prefer to construct the filter 16 chamber 34 as part of the developer housing 21, it will be 17 recognized that an independent filter housing with suitable 18 conveying means could be usefully employed. Thus, the subject 19 matter of our intention is intended to be limited only by the appended claims. We claim:
16 In operation, development material 22 is normally main-17 tained with a toner concentration that is substantially less 18 than the maximum concentration of which the carrier material 19 23 is capable. The portlon of the development material 22 that is diverted into filter chamber 34 is held in the path 21 of toner laden air flow 58. The substantially uniform thick-22 ness of the chamber 34 assures a substantially constant and 23 predictable air pressure drop accross the body of filter 24 material therein. As toner is captured by the carrier 23 within chamber 34 and the carrier thus approaches saturation, 26 it is moved progressively downwardly and eventually is 27 reintroduced into sump 25 where its captured toner is readily 28 mixed with the main body of development material 22. The 29 vertical orientation of walls 31 and 32 minimize the tendency for carrier beads to clog the openings in the mesh of walls 31 and 32. It will be recognized that this tendency could be 2 further minimized by a slight inclination of the walls 31 3 and 32 so that chamber 34 would widen slightly at its lower 4 end.
Cleaning unit 60 comprises a brush 61 in an enclosure 62 6 which can be constructed and operated like that described in 7 U. S. Patent 3,615,813. Brush 61 acts to dislodge particles 8 of the residual toner image 18 from imaging surface 12 and 9 carry them past a flicker bar 64 where they are ejected into an air s~ream created by a suitable vacuum source. Whereas 11 U. S. Patent 3,615,813 employs a replaceable filter bag in the 12 vacuum line, our .invention provides a return duct 66 connected 13 between cleaning unit .enclosure 62 and developer housing 21.
14 Blower 50 thus is placed in effective communication with cleaning unit enclosure 62 and develops the vacuum creating an 16 air flow to entrain airborne toner particles 68 flicked from 17 brush 61 and transport the entrained toner particles 68 into 18 developer .housing 21. Once in developer housing 21 the airborne 19 toner particles are further filtered as previously described by the body of developer material in filter chamber 34. It will 21 be recognized that our invention not only eliminates the need 22 for a cleaning station air filter but conveniently provides for 23 the recapture and reuse of toner material collected from the 24 residual image by the cleaning unit 60.
Figure 3 shows an alternate preferred embodiment where 26 only a lower portion of a developer housing 70 is illustrated.
27 Housing 70 supports a body of developer material 22, like that 28 described above, in a sump 71. The development material 22 is 29 transported past an electrostatic image on a copy drum (not shown) by conveyor 72. The body of development material 22 in 1 sump 71 is mixed and agitated by an auger 73. A porous wall 2 of screen mesh 74 contacts the body of de.velopment material 22 in a direction 75 between the horizontal and the nadir such 4 that carrier beads 23 are not held by gravity against the porous wall 74. A conduit 76 is connected to a suitable source 6 of sub-atmospheric pressure (not shown) to draw air from the 7 space 77 within the developer housing 70 through the body of 8 development material in sump 71 and the porous wall 74 which 9 forms the inlet to conduit 76. The development material 22 in the vicinity of porous wall 74 is continually moved during 11 operation by the action of conveyor 72 and mixing auger 73.
12 Those skilled in the art will recognize that various 13 modifications, additions and deletions can be made to the 14 preferred embodiment thus described. For example, while for compactness and simplicity we prefer to construct the filter 16 chamber 34 as part of the developer housing 21, it will be 17 recognized that an independent filter housing with suitable 18 conveying means could be usefully employed. Thus, the subject 19 matter of our intention is intended to be limited only by the appended claims. We claim:
Claims (8)
1. A xerographic printing machine having an imaging surface, and an image development station comprising a developer housing, means within said developer housing for conveying a developer mixture of relatively large carrier particles and relatively small toner particles into operative development relationship with a differential electrostatic charge image at said imaging surface, wherein the improvement comprises:
means supporting a body of said developer mixture within said developer housing, a source of sub-atmospheric air pressure, conduit means connected between said sub-atmospheric pressure source and said developer housing at a location that establishes a flow of air through said body of developer mix-ture whereby air suspended toner particles within said devel-oper housing are drawn into said air flow and through said body of developer mixture where said air suspended toner particles attach to the carrier particles in said body of developer mixture and are thereby separated from the air.
means supporting a body of said developer mixture within said developer housing, a source of sub-atmospheric air pressure, conduit means connected between said sub-atmospheric pressure source and said developer housing at a location that establishes a flow of air through said body of developer mix-ture whereby air suspended toner particles within said devel-oper housing are drawn into said air flow and through said body of developer mixture where said air suspended toner particles attach to the carrier particles in said body of developer mixture and are thereby separated from the air.
2. A xerographic printing machine as defined in Claim 1 wherein said conduit means comprises a porous wall contacting said body of developer mixture for drawing air through said body without removing carrier particles therefrom.
3. A xerographic printing machine as defined in Claim 2 wherein said porous wall contacts said body of developer mixture in a direction between the horizontal and the nadir whereby gravitational forces do not tend to maintain carrier particles in contact with said porous wall.
Claims 1, 2 and 3
Claims 1, 2 and 3
4. A xerographic printing machine as defined in Claim 1 further comprising cleaning means for removing residual toner particles from said imaging surface, said cleaning means comprising an enclosure, and means within said enclosure for dislodging said residual toner particles from said imaging surface and entraining said toner particles into air within said enclosure, wherein the improvement further comprises:
ducting interconnecting said enclosure with said developer housing whereby said sub-atmospheric pressure draws air bearing toner particles from said enclosure into said developer housing.
ducting interconnecting said enclosure with said developer housing whereby said sub-atmospheric pressure draws air bearing toner particles from said enclosure into said developer housing.
5. A xerographic printing machine having an image development station comprising a developer housing positioned adjacent an imaging surface, said developer housing providing a sump for retaining a mixture of development material including relatively large carrier particles and relatively small toner particles, wherein the surface characteristics of said carrier and toner particles are such that substantial triboelectric charge development occurs therebetween upon mutual contact, and means for circulating a portion of said developer material from said sump into operative development relationship with said imaging surface and back to said sump, wherein the improvement comprises:
means defining an auxiliary chamber, means for slowly moving a body of said developer material through said auxiliary chamber to said sump portion, means defining an air flow path through said auxiliary chamber, said air flow path having an upstream portion in communication with a source of airborne toner Claims 4 and 5 particles, and means for applying a sub-atmospheric pressure to a downstream portion of said air flow path.
means defining an auxiliary chamber, means for slowly moving a body of said developer material through said auxiliary chamber to said sump portion, means defining an air flow path through said auxiliary chamber, said air flow path having an upstream portion in communication with a source of airborne toner Claims 4 and 5 particles, and means for applying a sub-atmospheric pressure to a downstream portion of said air flow path.
6. A xerographic printing machine as defined in Claim 5 wherein said auxiliary chamber is positioned adjacent said developer material circulating means and wherein said means for slowly moving a body of said developer material through said auxiliary chamber comprises:
means for diverting a portion of the developer material being cir-culated by said developer material circulating means through said auxiliary chamber, and controlled gating means adjacent for regulating the rate of return of developer material from said auxiliary chamber to said sump.
means for diverting a portion of the developer material being cir-culated by said developer material circulating means through said auxiliary chamber, and controlled gating means adjacent for regulating the rate of return of developer material from said auxiliary chamber to said sump.
7. A xerographic printing machine as defined in Claim 6 wherein said means defining an auxiliary chamber comprises a pair of substantially uni-formly spaced, vertically extending mesh walls oriented transversley to said air flow path.
8. A xerographic printing machine as defined in Claim 6 wherein said source of airborne toner particles comprises a residual image cleaning station.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US42674673A | 1973-12-20 | 1973-12-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1042654A true CA1042654A (en) | 1978-11-21 |
Family
ID=23692044
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA213,223A Expired CA1042654A (en) | 1973-12-20 | 1974-11-07 | Toner recovery system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1042654A (en) |
-
1974
- 1974-11-07 CA CA213,223A patent/CA1042654A/en not_active Expired
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