Xerox Corporation

Standard Products Corporation

Frederick W Hudson

Robert W Gundlach

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 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 development roll either directly or by an intermediary transport roller.

Xerographic developing system rolls having magnets of different widths

A development system for developing latent magnetic images with magnetic toner comprises a developer housing having an upper chamber communicating through a selectively variable opening with a lower chamber, the lower chamber defining the development zone and being provided with peripheral edge seals. In operation, magnetic toner is gravity fed through the selectively variable opening to the lower chamber, filling the lower chamber to provide flood contact development of the latent magnetic image residing on a magnetizable member which is moved in a direction counter to that of gravity flow. Optional baffles are preferably included in the developer housing and above the development zone to prevent machine contamination by toner powder cloud during high speed development.

Developer housing

An improvement in development apparatus for developing a latent image with magnetic toner having a development zone defined at least in part by a sloping wall member along which magnetic toner migrates under the influence of gravity, residing in providing a flux channeling member affixed to the sloping wall member and within the development zone. Magnetic flux emanating from latent magnetic images passing through the development zone are channeled by the magnetic flux member and in cooperation with the magnetic toner forms a magnetic seal which prevents the flow of toner from the development zone. The present invention obviates the need to utilize a physical barrier which can cause damage to the surface of imaging members.

A development system for developing latent magnetic images with magnetic toner at high speeds comprises a developer housing comprising an upper toner supply chamber communicating through an opening with a sealed developer zone. The developer zone is defined by a lower wall member of the developer housing, a lip-seal attached to the developer housing at the entrance to the developer zone, the lip-seal being adapted to simultaneously reduce the turbulance of air flowing into the developer zone and to prevent toner from leaving the developer at the entrance thereto; a magnetic salvage assembly comprising magnetic field producing means, the magnetic salvage assembly being located above the developer zone, being adapted to remove airborne magnetic toner emerging from the developer zone and to direct said removed toner back into said toner supply chamber; and, intermediate said magnetic salvage assembly and said opening through which said toner supply chamber communicates with said developer zone, baffle means for redirecting a portion of airborne toner emerging from said developer zone into said toner supply chamber. Low friction resilient sealing means is provided on the developer housing along portions thereof engageable with a magnetizable imaging member bearing a latent magnetic image to be developed. The low friction sealing means is provided between said lip-seal at the entrance to the developer zone and said baffle means.

High speed tank development system

Apparatus for detecting bumps in a web, such as are caused by double threads or knots in a web of fabric, as the web is advanced past the detecting apparatus, comprises a blade, preferably a plurality of partially overlapping blades, arranged across the web and riding on the web. Each blade comprises one element of a switch the other element of which is constituted of a contact member arranged above the blade a distance from the blade greater than the height of the bumps to be detected. The blade is sufficiently light and so mounted that when it is struck by a bump on the web, it bounces out of engagement with the web and contacts the contact member thus closing the switch which is in an electrical circuit. A deactuatable means for moving the web is operatively associated with the switch whereby closing of the switch deactuates said web moving means. A marking means for marking the web when the switch is closed may also be operatively associated with the switch. Similarly, an audible signal may be operatively associated with the switch.

Apparatus for detecting bumps in a web

Toner particles which are removed from a photoconductive drum are trapped by a moving filter at a toner collection station and on movement of the filter to a toner discharge station, the toner is discharged into a toner reservoir. The filter may be of such a size that only the toner particles which enhance image development will be trapped thereon while the smaller toner particles will pass therethrough.

Toner reclaiming system

Vacuum removal means for removing excessive developer material from a member having a latent magnetic image developed with magnetic developer material. The vacuum removal means comprises a chamber having entrance and exit ports of predetermined cross-sectional area such that the ratio of entrance port to exit port is sufficiently small to assure substantially uniform air flow across the entrance port when the chamber is subjected to negative pressure through the exit port. The entrance port of the chamber is in communication with means for subjecting the developed surface of the member to a substantially uniform shearing air flow when the chamber is subjected to the negative pressure. A second entrance port of equal cross-sectional area to the first entrance port may be provided to the chamber in association with gating means for selectively varying the cross-sectional area of each entrance port while maintaining a constant combined cross-sectional area for the entrance ports.

Magnetic developer removal system

The developer storage capacity of a development system for an electrostatic processor is increased by adding a passive reservoir to supplement the system pump. Provision is made for maintaining a more or less continuous flow of developer into and out of the reservoir, including means for feeding developer from the reservoir to the sump whenever the supply of developer within the sump drops below a predetermined level. In a cascade development system, a hopper having a constricted discharge orifice leading to the development zone of the processor is filled to overflowing with developer so that there is a substantialy constant head causing the orifice to meter developer into the development zone at a substantially uniform rate. The reservoir is, in turn, positioned to intercept the overflowing developer and to feed developer into the sump whenever the supply of developer therein drops below the bottom of the reservoir.

Electrostatic development system with passive storage capacity

A development method and device for developing a latent image wherein an irregular surfaced vibrating bed transports toner particles from a supply area to the development area.

Development device and method

An electrostatic charging apparatus in which current reaching an imaging surface from a corona discharge device is automatically regulated. A sensing means is provided to measure the charging current delivered to the imaging surface and means responsive to said measured charging current to adjust the D.C. bias of an A.C. power supply energizing the corona electrode.

Self adjusting corona device

There is disclosed a device and method for measuring the angle of repose of a granular material. The device is composed of a rectangular body having an open ended partition dividing the body into two cells. A sample of granular material is placed in one cell and allowed to flow from one cell into the other cell under the influence of gravity. Both the static and dynamic angle of repose can be determined.

Apparatus and method for measuring angle of repose

There is provided an electrostatic copying apparatus having means for delivering a toner material consisting of relatively small particles, a portion of which exist in an air suspension, to an image retention surface for developing a latent image on the surface, a housing for forming with the surface an enclosure for the toner material delivery means, said housing and said surface forming an air gap interface therebetween, and means positioned near said air gap interface for electrostatically precipitating and collecting the toner particles existing in air suspension thereby reducing the flow of particles from the housing through the interface. The toner particles cascaded over the surface are charged to a first polarity opposite to that of the image; the unwanted particles in air suspension have charges of both the first polarity and the opposite polarity. To attract the oppositely charged particles in air suspension the precipitating member, in the form of a roller, is held at a potential of the first polarity -- i.e., opposite to the image and the same as the cascading particles. The remaining suspended particles, those of the first polarity, are repelled by the roller and are attracted by the latent image on the surface in the same manner as the cascaded particles.

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West Henrietta, NY, United States of America

Frederick W Hudson