US3542089A - Toner dispenser - Google Patents

Description

United States Patent Gopal C. Bhagat Rochester, New York 744,159

July 1 1, 1968 Nov. 24, 1970 Xerox Corporation Rochester, New York a corporation oi New York TONER DISPENSER 4 Claims, 1 Drawing Fig.

Int. Cl B65b 1/04, B65b 3/04 Field oi'Search ml/1,256; 222/lnq, 70, 226; 3l7/lnq, 3. 262; 353/lnq;

Inventor Appl. No. Filed Patented Assignee References Cited UNITED STATES PATENTS 2,965,266 12/1960 Rutkus et al Primary ExaminerHouston S. Bell, Jr. Auorneys Paul M. Enlow, Norman E. Schrader, James J.

Ralabate. Ronald Zibelli and Clarence A. Green ABSTRACT: An apparatus and method for dispensing toner to a developing member including a dlspenser which mechaniticles to the developing member upon which they are deposited.

carrier beads in a developer mixture and carries the toner par- Patented Nov. 24, 1970 3,542,089

. INVENTOR. GOPAL C. BHAGAT TONER DISPENSER This invention relates to developing electrostatic latent images and, in particulanto dispensing charged toner particles onto a developing member.

, ln xerography and related arts, an electrostatic latent image isformed on a xerographic plate. In order to make the latent image visible, marking particles such as toner are placed in contact with the xerographic plate where they are deposited in image configuration due to the pattern of electric fields on the plate, A two-component developer composed of a mixture of electrostatically attractable toner particles and a granular carrier images. i i 7 One method'of depositing toner on a plate bearing an electrostatic latent image is by cascade development. For instance, wher e the xerographic plate takes the form of a drum in an automatic xerographic apparatus, such as that shown'in U.S. Pat. No. 3,190,264, the cascade developing system customarily has a vertical or inclined conveyor apparatus to transport developer from a reservoir to an elevated system of chutes or guides which directthe gravitational flow of developer onto the peripheral surface of the xerographic drum. The buckets on the conveyor system are arranged parallel to the axis of the drum and have a transverse length approximately equal to thewidth of the drum surface. As the developer falls across the surface of the drum, the toner particles adhere to the xerographic plate according to the configuration of the latent image while the carrier beads continue downwardly and into a sump. The carrier beads are retoned and then recirculated by the conveyor.

Another manner by which toner is deposited on a xerographic plate is with the use ofa fibrous developing brush. The brush can be made of any suitable material such as rabbit fur, fox fur, camel hair,.dynel, (a synthetic fiber of 40 percent acrylonitrile and 60 percent vinyl chloride), or any other suitable natural or synthetic material. The fibrous members of the brush act as carriers-and serve a function similar to'the carrier beads in the'developer mixture. A developing brush impregnated with toner particles is brought in contact with the plate bearing the latent image and the particles are deposited upon the plate in imagewise configuration thereby developing the latent image. I a

An undesirable aspect ofdeveloping latent imageswith brushlike materials is that there is not any known way of efficiently loadingthe developing brush with charged toner particles. One known method is to rotate the brush in a reservoir of toner thereby allowing the fibers to pick up the toner particles from the reservoir and deposit them on the plate being developed. This method has an inherent disadvantage in that as the brush continues to rotate it creates a cavity in thereservoir described by the path through which it rotates and fewer and fewer particles contact the fibers. This condition worsens as the brush continues to rotate, even when a mixing apparatus is added in order to keep the reservoir in a loose consistency. I

A second method of loading a developing brush is to place a hopper of toner over the brush and feed toner from it to the brush. The hopper includes a mesh bottom which allows toner to pass onto the brush as the hopper is vibrated. This method is undesirable at high brush speeds in that at high brush speeds inadequate and uneven amounts of particles are distributed on the brush and the particles are not uniformly charged.

The present invention is intended to overcome the prior difficulties of loading a developing member by causing the charged toner particles to be placed on the developing member through the use of a dispenser. Accordingly, it is an object of the present invention to overcome the problems of loading a developing member as occurred in the prior art.

It is another object of the invention to improve developing apparatus for the development of electrostatic latent images.

It is a further object of the invention to improve dispensing apparatus for loading toner particles on a brushlike member.

material is commonly used to develop electrostatic it is still a further object of the invention to improve dispensing apparatus for loading charged toner particles on a developing member. I

it is still a further object of the invention to improve dispensing apparatus which removes charged toner particles from carrier beads in a developer mixture.

The present invention is an apparatus and method for dispensing charged toner particles onto a developing member. Developing material consisting of a mixture of toner particles and carrier heads is placed in a collecting station. ln contact with the developing material and the developing member is a dispenser which removes charged'toner particles from the granular carrier beads and carries them to a dispensing station adjacent the developing member. The toner particles so carried are deposited on the developing member which, in turn, develops aplate bearing an electrostatic latent image. As the system operates and toner particles are removed from the carrier beads, the denuded carrier beads flow to the bottom of the collecting station where they are retoned with toner particles fed from atoner reservoir. An auger of some other suitable moving means carries the carrier beads which have been retoned into an area-where they are collected by buckets on a conveyor which recirculates the developing mixture through the system.

For a better understanding of the invention as well as other objects and further features thereof, reference is had to the machine is photosensitive plate 60. The plate has five distinct stations arranged about its periphery which carry out the operational steps of the xerographic process. These stations include charging station. 10,,exposing station 20, developing station 30, transfer station-40, and cleaning station 50.

The plate is in the shape of a rotatable drum 63 which is driven about shaft 64 by a motor (not shown). The drum comprises a layer 62,, an electrically conductive material, which, in turn, is covered on its outer surface with layer 61, a photoconductive insulating material such as vitreous selenium.

An electrostatic latent image is formed on the surface of the drum by passing it through charging station 10 and exposing station 20. The charging station consists of any suitable means for placing a uniform charge on layer 61 such as corona charging device 11.

Exposure station 20 comprises a projector 21 which proimage projected onto the photosensitive layer of the drum is synchronized with the movement of the drum. The projected light pattern-causes selective charge dissipation on elemental areas'of layer 61, thus forming an electrostatic latent image.

Other means for forming an electrostatic latent image including means for forming images on ordinary insulating surfaces can be used and these are known in the art and may be used instead ofthe one shown.

After the formation of the electrostatic latent image the drum passes through developing station 30. At the developing station, the developing system includes developingapparatus 70 and toner dispensing apparatus working in combination to deposit charged toner particles on the surface of the drum in conformance with the configuration of the electrostatic latent image. In the case of the xerographic system shown in the drawing, the toner particles consist of the finely-divided particles of thermoplastic resins having colored pigments dispersed throughout such as those disclosed in U.S. Pat. No.

. aided by corona charging device 42 which applies an electrostatic charge to the support materialhaving a polarity opposite that of the toner particles. .Transfer of the developed image from the photosensitive surface to the support'material takes place between guide. rollers 45 .which act to position the support material against the, photosensitive drum at the transfer station.

Support material 41 is fed from reel 43 before transfer and is rewound on reel 44 aftertransfer takes place.'lf the support material is the permanent substrate upon which the image-is to be fixed, a' fixing device such asfuser 46 can be placed along the path of'the'support material between the point where the developed image is transferred to the support material and the point where the supportmaterial is rewoundon reel 44. The fuser is positioned to heat the toner and permanently bond it to the support material.

The final station shown in the FIG. is cleaning station 50 which comprises cylindrical brush' '51 which contacts-thephotosensitive surface of the drum. The cleaning station is desirable to remove any residue marking particles from the photosensitive surface after transfer hastaken place. and be- 7 fore the surface begins a new cycle-The abovedescribed process and apparatus are commercially known in the art as v evidenced in U.S; Pat. No. 3,117,891 and any of the many known equivalents of process or apparatus may be employed in connection with the present invention.

lt-is within the development station, station 30, that the present invention is utilized, As was; mentioned above, the

development system at station 30 has vtwo cooperating apparatus; developing apparatus 70 and dispensing apparatus 80. The-developing apparatus can be any type of apparatus carrier should be selected so that the toner particles are triboelectrically negative relative to the granular carrier. This triboelectric relationship between the toner particles and granular carrier depends on their relative position in the t'riboelectric series. In this series, the materials are arranged in such a way that each material is charged with positive triboelectriccharge when contacted with anymaterial below itin the series and with negative triboelectric charge when contacted with any material above'it ina series. The'relative movement of the powder and granular materialcauses a rubbing. action between the two triboelectrically-dissimilar materials and thereby produces triboelectric charge on each.

which isable to receive charged toner particlesand place I them on the surface .of drum 63; in the illustration there is shown fur belt 71 which is supported and driven by rollers 72.

The outer surface of this developing member is brushlike in character having a multitude of elongated carrier members such as cloth or brush fibers extending outwardly from. the belt. In general, this member may be a brushlike surface of fur or the like, cloth'such as yelvetlike cloth having a fibrous surfac c,a weblike surface having elongated members or .fibe'rs' extending therefrom, or other support surface bearinga mul- .tiplicity ofelongated carrier members on its surfacefAtth'ej' point were the belt contacts the photosensitive'surface thebelts brushlike-surface deposits finely-divided toner particles on the surface of the drum. The developingrnember can also take the shape of a rotatable brush having a multitude of elon- V gated carrier members or fibers, the fibers being analogous to the fibers of the belt as shown in the FIG. Dependingon the speed of the machine, more than one belt and/or brush can be used to carry toner to the xerographic plate.

In the, alternative, developing member 71 can be any suitable material such as cloth, mylar, or other nonpile material which will convey toner to the point where they are deposited on the surface of the drum.

Dispensing apparatus 80 serves the function of dispensing or placing charged toner particles on the'de'veloping member. it can assume any suitable shap'esuch as a roller, endless belt, etc. The dispensing apparatusvis enclosed by housing- 82, except in the area where dispenser 81 is located. Developing mixture 88 consisting of carrier beads having toner; adhering thereto is brought to an elevated position near the top of conveyor housing 82. The conveyor has a multitude of scoops 86 and is supported and driven by rollers 85. As the conveyor moves in the counterclockwise direction around its roller the scoops are brought through the developing mixture atthe bottom of the housing where they are filled. The scoops bring the developing mixture to a position near the top of the housing where the developing mixture is dumped onto dispenser 81. Partition 84, keeps all of the developer released by the'scoops in the area surrounding the dispenser. At the bottom of the housing is auger 83 ora group of augers, or some similar type apparatus which mixes additional toner particles fed from toner reservoir 87 with the carrier beads. The auger then moves the mixture to the bottom of the conveyor where the mixture is recirculated.

Due to the action of the auger and the movingscoopsthere is created within housing 82 a circulating flow of the developing material which carries it adjacent dispenser 81. The area where the mixture contacts the dispenser is collecting station 89. At thecollecting station the dispenser rotates thereby mechanically. and/or triboelectrically stripping the charged toner-particles from the carrier beads. The particles are then carried out of thehousing by the dispenser to dispensing station 99 where they are deposited on developing member 71.

The surface of dispenser 8 1- is made of a material 98 which I I is located ata position in, the 'triboelectric series which is different than that of the toner particles. The entire dispenser can be made of material 98, or, as shown, material 98 cancomprise an'outer layer aroundcore 97. Depending upon whether the latent electrostatic image is developed with positively or negatively -toner particle's, a specific material is chosen for the surface of the dispenser. As was mentioned charged positive. Therefore, in order to triboelectrically strip negatively charged toner particles from their respective carrier beads, the material on the surfaces of the dispenser must occupy a position in the triboelectric series which is above the position occupied by the-toner particles. When negativelycharged toner particles are used, silk mesh, for example, can

be used on the surfaces of the dispenser. The surface material on the dispenser can be chosen depending upon the magnitude of the charge which is placed on the toner particles Since the charge already exists on the toner particles due to' their mixing with the carrier beads, an electrical bias can be placed on the dispenser to enhance the attraction of the toner particles. If the particles bear a charge of negative polarity, for

instance, a positive electrical bias can be placed on the surface of the dispenser to attract the toner. If this were done, a positive electrical bias of larger magnitude should be placed on the furibelt to transfer the toner from the dispenser to the belt at dispensing station 99.

Dispenser 81 canalso be used as a collecting member merely to remove toner particles from a developing mixture. In order-to accomplish this simpler result, the same considerations as described above will govern the choice of material used on the surface of the collecting member.

Dispenser 81 rotates and collects charged toner particles on its surface; The clearance between housing 82 and the dispenser is sufficient to allow' a layer of the toner particles on the dispenser to exit the housing. Due to the fibrous nature of developing member 71, the charged toner particles on the dispenser are readily transferred to the developing station.

Z above, any material used on the surface of the dispenser which 'is above the toner particles in the triboelectric series will be The transfer of toner from the dispenser to the developing materials can also be aided by choosing the material of the developing member so that it is triboelectrically attractive to the toner particles,

Although the various drive and control apparatus necessary to make the system operate as disclosed above are not specifically shown or discussed, it is intended that any suitable apparatus be used andthat such a suitable apparatus be part of this general disclosure. For example, a unitary motor can be used to drive the cascade device, dispenser and fur belt through appropriate gear systems.

1. An apparatus fordispensing electrostatically-attractable l having a triboelectric property different than that of the toner particles and adapted to acquire and electrostatic charge of a first magnitude due to the triboelectricaction with the toner particles comprising:

a movable dispenser in contact with the surface of the developing member at a dispensing station, the surface of the dispenser comprising a material having atribo'electric property different than that of the toner particles and adapted to acquire an electrostatic charge of a second magnitude due to triboelectric actionflwith the toner particles, said second magnitude being of less value than said first magnitude; 7

means for placing developing material in contact with the surface of the dispenser at a'collecting station located adjacent the dispensing station, the developing material comprising a mixture of coated granular material and electrostatically-attractable toner particles, said coating and toner particles having a triboelectric relationship of opposite polarity and being attracted to one another with a force of a third magnitude, said third magnitude being of less value than said second magnitude; and

means for moving the dispenser so that at least a portion of its surface passes through the dispensing station and the collecting station.

2. The apparatus in claim 1 wherein the means to place developing material in contact with the surface of the dispenser is a conveying apparatus adapted to transport the developing material to an elevation over the dispenser and cascade the" developing material over the surface of the dispenser.

3. An apparatus for removing electrostatically-attractable toner particles having a predetermined triboelectric property means for rotating the collecting member in contact with the mixture. 4. A method of removing electrostatically-attractable toner particles having a predetermined triboelectric property from a mixture of coated granular material and toner particles, the

coatingand toner particles having a triboelectric relationship of opposite polarity and being attracted to one another by an electrostatic charge of a first magnitude due to triboelectric action, comprising rotating a collecting member in a reservoir of the mixture, the surface of the collecting member having a triboelectric property different than that of the toner particles and the surface acquiring an electrostatic charge of a second magnitude due to triboelectric action with the toner particles, the second magnitude being of greater value than the first magnitude.

Images