초록 ▼

A development system for an electrophotographic machine in which uncharged toner is stored in a housing having an opening. A rotatable dispensing roll is mounted in the housing opening. An overhung metering blade mounted at the housing opening meters a layer of uncharged toner onto the dispensing ro

A development system for an electrophotographic machine in which uncharged toner is stored in a housing having an opening. A rotatable dispensing roll is mounted in the housing opening. An overhung metering blade mounted at the housing opening meters a layer of uncharged toner onto the dispensing roll. An ion or electron charging device places a charge on the toner layer residing on the dispensing roll prior to the transportation thereof by the dispensing roll to a captive magnetic brush. The magnetic brush transports the two component developer on the magnetic brush to a development zone for either direct development of a latent image on a moving imaging surface or to coat donor rolls for AC/DC generated toner cloud development of a latent image.

대표청구항 ▼

What is claimed is: 1. A two component development system for developing an electrostatic latent image on an imaging surface of an electrophotographic machine, comprising: a housing containing a supply of uncharged toner, said housing having an opening with two parallel opposing lips; a first rotat

What is claimed is: 1. A two component development system for developing an electrostatic latent image on an imaging surface of an electrophotographic machine, comprising: a housing containing a supply of uncharged toner, said housing having an opening with two parallel opposing lips; a first rotatable dispensing roll positioned in said housing opening and in contact with said supply of toner, the first dispensing roll being parallel to said housing lips; a metering blade mounted on one of said housing lips and in contact with said first dispensing roll, said metering blade being arranged for metering a layer of uncharged toner onto said first dispensing roll; a rotatable magnetic brush having magnetic, conductive or semi-conductive carrier beads thereon, said carrier beads being in contact with said layer of toner on said first dispensing roll, and said magnetic brush having a length substantially equal to the width of said imaging surface; a first ion or electron charging device confronting said first dispensing roll and being positioned between said housing and said magnetic brush and downstream from said metering blade for placing an ion or electron charge on said layer of toner on said first dispensing roll prior to contact of said layer of toner with said magnetic brush; a voltage source being connected to said magnetic brush for assisting in the transfer of the ion or electron charged toner from said first dispensing roll onto the carrier beads of said magnetic brush to form a layer of two component developer on said magnetic brush; and said magnetic brush being rotated toward a development zone where an electrostatic latent image recorded on a moving imaging surface is developed. 2. The development system as claimed in claim 1, wherein said housing is positioned above said first dispensing roll, so that gravity assists in maintaining said supply of uncharged toner in said housing against said first dispensing roll. 3. The development system as claimed in claim 1, wherein said magnetic brush comprises a rotatable outer tubular member for holding carrier beads captive thereon, and a magnetic cylindrical member having magnetic pole pieces spaced there around, said cylindrical member with said pole pieces being located within said tubular member; and wherein said tubular member and said cylindrical member are rotated in opposite directions to assist in the lateral diffusion of said charged toner with said carrier beads, whereby a relatively uniform layer of two component developer is maintained on said magnetic brush. 4. The development system as claimed in claim 1, wherein said first ion or electron charging device is a wire or pin corotron or a screen scorotron. 5. The development system as claimed in claim 1, wherein said first ion or electron charging device comprises nanotubes. 6. The development system as claimed in claim 1, wherein said housing, first dispensing roll, and first ion or electron charging device are mounted on a translatable carriage for translation thereby, said housing and said first dispensing roll have a length shorter than said magnetic brush, said carriage being translated back and forth in a direction parallel to said magnetic brush, so that said first dispensing roll may meter charged toner therefrom onto selected regions of said magnetic brush where said layer of two component developer may have toner depleted therefrom. 7. The development system as claimed in claim 6, wherein said first dispensing roll has a length of 5 to 15 cm. 8. The development system as claimed in claim 6, wherein said housing mounted on said translatable carriage has an aperture therein, a toner supply bottle containing uncharged toner, and a flexible tube interconnecting the supply bottle and said housing aperture. 9. The development system as claimed in claim 8, wherein said flexible tube has a rotatable spiral transporter therein for moving said uncharged toner from said supply bottle to said housing on said translatable carriage. 10. The development system as claimed in claim 1, wherein said development zone further comprises at least one donor roll located between said magnetic brush and imaging surface with said electrostatic latent image thereon, said at least one donor roll being in contact with said magnetic brush and spaced from said imaging surface to form a gap there between, whereat a toner cloud is formed to develop said electrostatic latent image on said imaging surface. 11. The development system as claimed in claim 10, wherein said development zone has a pair of donor rolls in contact with said magnetic brush and spaced from said imaging surface to form said development zone whereat said toner cloud is formed to develop said electrostatic latent image on said imaging surface. 12. The development system as claimed in claim 1, wherein said development system further comprises; a second dispensing roll positioned between and in contact with said first dispensing roll and said magnetic brush; a second ion or electron charging device adjacent said second dispensing roll; and at least one donor roll located between said magnetic brush and imaging surface, said at least one donor roll being in contact with said magnetic brush and spaced from said imaging surface to form a gap there between, said gap defining said development zone, whereat a toner cloud is formed to develop an electrostatic latent image on said imaging surface. 13. The development system as claimed in claim 1, wherein said metering blade has a distal end and contacts said first dispensing roll at a location spaced from said distal end of said metering blade, so that said metering blade overhangs said first dispensing roll and permits the uncharged toner from said housing to wedge underneath said distal end of said metering blade, whereby the amount of overhang of said distal end of said metering blade establishes the thickness of said layer of toner on said first dispensing roll. 14. The development system as claimed in claim 1, wherein said development system further comprises a wiper blade mounted on said other lip of said housing opening, the wiper blade being oriented in a doctor blade position to remove toner from said first dispensing roll when said rotational direction of said first dispensing roll is reversed from a printing direction prior to a prolonged shutdown of said development system. 15. A two component development system for developing an electrostatic latent image on an imaging surface of an electrophotographic machine, the imaging surface having a width that determines the process printing width of said machine, comprising: a rotatably mounted magnetic brush having a length at least equal to said process printing width; a translatable carriage being adapted for translation adjacent and parallel to said magnetic brush; a housing having a length H shorter than said magnetic brush and containing a supply of uncharged toner, said housing being mounted on said carriage for translation thereby, and having an elongated opening with two opposing parallel lips and an aperture for refilling said housing with uncharged toner; a first dispensing roll rotatably mounted on said carriage at a location adjacent said housing opening and parallel to said housing lips, the location of said first dispensing roll being fixed relative to said housing and in contact with said magnetic brush, so that the housing and first dispensing roll are translated together on said carriage back and forth in a direction parallel to and along the length of said magnetic brush, during the translation of the carriage, the first dispensing roll remains in contact with said magnetic brush at a location generally opposing the housing opening, said first dispensing roll being in contact with said uncharged toner in said housing at said housing opening and having a length D shorter than said magnetic brush but longer than said housing; a metering blade mounted on one of said lips of said housing opening and having an overhanging contact with said first dispensing roll to meter a layer of uncharged toner onto said first dispensing roll from said housing opening; an ion or electron charging device mounted on said carriage for translation thereby, said ion or electron charging device being positioned adjacent said first dispensing roll and between said metering blade and said magnetic brush, so that said layer of uncharged toner on said first dispensing roll is charged prior to being transported to said magnetic brush by said first dispensing roll to form a layer of two component developer on said magnetic brush; and drive means for translating said carriage along said magnetic brush so that said first dispensing roll may meter charged toner onto and along the length of said magnetic brush. 16. The development system as claimed in claim 15, wherein said development system further comprises: a second dispensing roll rotatably mounted on said carriage between and in contact with said first dispensing roll and said magnetic brush, said second dispensing roll being substantially the same as said first dispensing roll; and a second ion or electron charging device mounted adjacent said second dispensing roll and on said carriage for translation thereby, said second ion or electron charging device being located between said first dispensing and said magnetic brush whereby the toner is more uniformly charged prior to being deposited on said magnetic brush by said second dispensing roll. 17. The development system as claimed in claim 15, wherein said development zone further comprises at least one rotatably mounted donor roll positioned between the magnetic brush and said imaging surface, said at least one donor roll being in contact with said magnetic brush and spaced from said imaging surface to form a gap between said donor roll and said imaging surface, whereat a toner cloud may be produced with the aid of an AC and DC electrical bias applied to said donor roll to develop an electrostatic latent image on said imaging surface. 18. The development system as claimed in claim 15, wherein said development system further comprises a toner concentration sensor mounted adjacent said magnetic brush to sense toner depleted regions in said layer of two component developer on said magnetic brush, so that said first dispensing roll may be transported by said carriage directly to said toner depleted regions in said layer of two component developer. 19. A two component development system for developing an electrostatic latent image on an imaging surface of an electrophotographic machine, comprising: a housing containing a supply of uncharged toner, said housing having an opening with two parallel opposing lips; a first rotatable dispensing roll positioned in said housing opening and in contact with said supply of toner, the first dispensing roll being parallel to said housing lips; a metering blade mounted on one of said housing lips and in contact with said first dispensing roll, said metering blade being arranged for metering a layer of uncharged toner onto said first dispensing roll; a rotatable magnetic brush having magnetic, conductive or semi-conductive carrier beads thereon, said carrier beads being in contact with said layer of toner on said first dispensing roll, and said magnetic brush having a length substantially equal to the width of said imaging surface; a first ion or electron charging device confronting said first dispensing roll and being positioned between said housing and said magnetic brush and downstream from said metering blade for placing an ion or electron charge on said layer of toner on said first dispensing roll prior to contact of said layer of toner with said magnetic brush, wherein said first ion or electron charging device is selected from the group consisting of a wire corotron, a pin corotron, a screen scorotron, and carbon nanotubes; a voltage source being connected to said magnetic brush for assisting in the transfer of the ion or electron charged toner from said first dispensing roll onto the carrier beads of said magnetic brush to form a layer of two component developer on said magnetic brush; and said magnetic brush being rotated toward a development zone where an electrostatic latent image recorded on a moving imaging surface is developed.