US3622054A

US3622054A - Toner dispenser improvement

Info

Publication number: US3622054A
Application number: US830237A
Authority: US
Inventors: James R Davidson
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1969-06-04
Filing date: 1969-06-04
Publication date: 1971-11-23
Anticipated expiration: 1988-11-23

Abstract

An antibridging roller, having openly spaced, semirigid fibers extending from a central axis is contained within a dispensing apparatus and rotatably supported by a dispensing roller. Partial epicyclic movement of the agglomeration-preventing roller may be effected by rotational movement of the dispensing roller.

Description

United States Patent Inventor James R. Davidson Rochester, N.Y.

Appl. No. 830,237

Filed June 4, 1969 Patented Nov. 23, 1971 Assignee Xerox Corporation Rochester, N.Y.

TONER DISPENSER IMPROVEMENT 4 Claims, 6 Drawing Figs.

U.S. C1 222/414, 222/236, 222/238, 222/231 Int. Cl 601111/20 Field 01 Search 222/414,

177, DIG. 1, 236-238, 228, 231

[56] References Cited UNITED STATES PATENTS 3,149,760 9/1964 222/238 3,128,015 4/1964 222/177 2,578,482 12/1951 222/414 UX 2,643,798 6/1953 222/414 3,176,881 4/1965 Malby et a1. 222/414 Primary Examiner-Robert B. Reeves Assistant Examiner-James M. Slattery Attorneys-James]. Ralabate, Norman E. Schrader and Bernard A. Chiama ABSTRACT: An antibridging roller, having openly spaced.

semirigid fibers extending from a central axis is contained within a dispensing apparatus and rotatably supported by a dispensing roller. Partial epicyclic movement of the agglomeration-preventing roller may be effected by rotational movement of the dispensing roller.

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sum 3 [IF 3 1 TONER DISPENSER IMPROVEMENT BACKGROUND OF THE INVENTION This invention relates to apparatus for dispensing finely divided particulate matter and, in particular, to improvements in apparatus for preventing the agglomerating or bridging of particulate material contained in a dispensing apparatus.

While the apparatus of this invention is of general utility in the dispensing of granular or powdered particulate matter, it is particularly well suited for use with eiectroscopic toner powder and, therefore, will be describedwith reference to its use in a xerographic toner powder dispenser to dispense electroscopic toner powder to the developing mechanism of an automatic xerographic reproducing machine. In the process of xerography, latent electrostatic images are rendered visible by the application of a developer material which comprises, in general, a mixture of suitable pigmented or dyed resin-based powder, hereinafter referred to as toner, and a granular carrier material which functions to generate triboelectric charges on, and to carry the toner. The toner powder is brought into surface contact with a photoconductive surface bearing a latent electrostatic charge pattern in image configuration and is held thereon electrostatically in a pattern corresponding to the latent electrostatic image. Thereafter the developed toner powder image may be transferred to a support material to which it may be fixed by any suitable means such as heat fusing, or the toner powder may be fixed to the latent electrostatic image bearing surface, depending on the photoreceptor used as is well known in the electrosta tographic art.

One well-known method of latent electrostatic image development is referred to in the art as cascade development. During cascade development, the toner coated carrier material rolls or tumbles over the photoreceptive surface carrying an electrostatic charge pattern of opposite polarity to the charge on the toner and, therefore, toner particles are pulled from the carrier by the latent electrostatic image and deposited on the plate to form a developed toner powder image. As toner powder images are formed, additional toner powder must be supplied to the developer mixture to replenish the toner deposited during image development. The toner material may be of the type disclosed in Carlson, US. Pat. No. 2,940,934, wherein the toner particles comprise a finely divided pigmented resin having a particle size less than 20 microns and preferably an average particle size between about 5 and microns and comprising a finely divided uniform mixture of pigment in a nontacky, low-melting resin. Desirably, the pigment will be a black pigment such as carbon black or other minutely divided carbonaceous pigment.

As the toner powder in a developer mixture is depleted during the development of the latent image on the xerographic plate, more toner powder must be added to maintain a desirable levelof copy density. The addition of toner powder to the developer mixture has heretofore been an inconvenient procedure which resulted in undesirable contamination of the surrounding areas with carbon black particles, blackening an operator's hands and clothing creating an undesirable working condition. These undesirable effects were due to the necessity of pouring the toner powder into a dispensing system which allowed the toner powder, due to its minute size, to become airborne when the container was open and poured into the dispensing apparatus. One attempt to solve this undesirable problem has been the use of a container of the type wherein the toner powder containing package is placed into the machine by the operator and kept therein to be used as a hopper for the dispensing unit. However, after the toner supply is exhausted, the operator must remove the empty container from the machine and replace it with a full one. Minute toner particles which cover the empty container, due to the dispensing operation, and the residual powder remaining inside the open container create the same problem as described above but of a more aggravated nature.

Another attempt to overcome the problems associated with prior art toner powder containers and dispensers has been the use of a sealed toner powder package which is placed into an appropriate receptacle, the seal broken and the entire contents of the container emptied into the dispensing apparatus The container is then reclosed and removed from the mounting for disposal. This apparatus while eliminating some of the problems of the prior art in handling the toner powder, is expensive and requires a special mounting to be utilized on the toner dispenser to provide an adequate seal for the container during the time the contents of the container are emptied into the dispenser apparatus.

These problems associated with toner powder containers and dispensers have been overcome by a novel dispenser comprising a sealed container including an integrally fonned dispenser which rapidly and accurately delivers a uniformly distributed quantity of electroscopic toner powder into the development system. Such a dispenser is the subject matter of copending application, Ser. No. 830,367 entitled Dispensing Apparatus" filed concurrently herewith in the name of Frederick W. Hudson.

However, it has been found that the apparatus referred to in the above identified copending application, while solving the problems heretofore associated with the prior art dispensing devices, has not proven entirely satisfactory for dispensing all types of electroscopic toner powder. The minute eiectroscopic toner powder which is contained in the dispenser, due in part to its electroscopic nature, has a tendency to form a bridge above the dispensing roller. The roller will dispense the toner powder adjacent to its surface but, due to the bridging action of the toner powder, once this toner material has been removed the dispenser will cease to function. Therefore, it is necessary for the continuous functioning of the dispensing mechanism to prevent the formation of the toner powder bridge to ensure uniform and accurate distribution of the toner powder.

SUMMARY OF THE INVENTION It is, therefore, an object of this invention to improve apparatus for dispensing particulate or granular material.

Another object of this invention is to prevent agglomeration or bridging of the particulate matter to maintain its granular state.

A further object of this invention is to maintain the granular material in a particulate state to assure the uniform dispensing of the material.

These and other objects are attained in accordance with the present invention wherein there is provided an antibridging apparatus carried within the dispensing apparatus and supported by the dispenser roll to maintain the contents of the container in a particulate state to ensure the uniform dispensing thereof.

DESCRIPTION OF THE DRAWINGS Furtherobjects of the invention, together with additional features contributing thereto and advantages accruing therefrom, will be apparent from the following description of one embodiment of the invention when read in conjunction with the accompanying drawings wherein:

FIG. l.is a mechanical schematic of an automatic xerographic reproducing apparatus utilizing this invention;

FIG. 2 is an enlarged portion of the developing apparatus of the automatic xerographic reproducing machine illustrated in FIG. 1 in a partial section to better illustrate the antibridging apparatus;

FIG. 3 is a front perspective view of the dispenser apparatus utilizing the present invention to better illustrate the features thereof;

FIGS. 4 and 5 are end profile sections of the dispenser. apparatus as illustrated in FIG. 3 taken along lines 4-4 and 5-5 respectively; and

FIG. 6 is a partial section view of the dispenser apparatus as illustrated in FIG. 4 taken along line 6-6 to better illustrate the mounting of the dispenser roll.

DESCRIPTION OF A PREFERRED EMBCDlMENT Referring now to the drawings, there is shown in FIG. 1 an embodiment of the subject invention in a suitable environment such as an automatic xerographic reproducing machine, although it should be noted that the invention is not intended to be limited thereto. The automatic xerographic reproducing machine includes a xerographic plate 1 having a photoconductive layer or light receiving surface on a conductive backing, journaled in a frame to rotate in the direction indicated by the arrow to cause the plate surface to sequentially pass a series of xerographic processing stations.

For the purpose of the present disclosure, the several xerographic processing stations in the path of movement of the plate surface may be described functionally, as follows:

A charging station 2 at which a uniform electrostatic charge is deposited on or in the photoconductive plate;

An exposure station 3 at which a light or radiation pattern of copy to be reproduced is projected onto the plate surface to dissipate the charge in the exposed areas thereof to thereby form a latent electrostatic image of the copy to be reproduced;

a developing station 4 at which the xerographic developing material, including toner particles having an electrostatic charge opposite to that of the latent electrostatic image, are applied to the plate surface whereby the toner particles adhere to the latent electrostatic image to form a toner-powder image in configuration of the copy being reproduced;

A transfer station 5 at which the toner-powder image is transferred from the plate surface to a transfer material or a support surface; and

A drum cleaning and discharge station 6 at which the plate surface is brushed to remove residual toner particles remaining thereon after image transfer, and exposed to a relatively bright light source to effect substantially complete discharge of any residual electrostatic charge remaining thereon or therein.

It is felt that the preceding description of the xerographic process is sufficient for a better understanding of this inventron.

Referring specifically to FIGS. 2, 3 and 4, there is shown in detail a toner dispenser in which toner material is carried within flaccid baglike container 30 to be dispensed directly into the developer material by means of a dispensing roll adapted to pick up particles of toner powder stored within the container and uniformly dispense the powder into a supply of developer material. in order to ensure uniform distribution of new toner, the toner dispenser roll extends substantially the length of the developer apparatus 50 and delivers an even quantity of toner throughout the entire width of the developer housing.

The toner dispensing apparatus 10 includes a flaccid baglike container 30 closed at one end by the dispensing mechanism and appropriately sealed at the opposite end to retain toner powder material therein. A resilient support member 31 is carried in suitable recesses by the base 26 of the dispensing mechanism and supports the container 30 to prevent its collapsing during dispensing of the toner powder material contained therein. The container 30 is secured to the base 26 to form a toner tight seal by means of a semi or nondeformable member such as a wire or vinyl type tubing 32 appropriately secured to portion 33 of the container, as by adhesive or heat bonding, which in cooperation with the dispensing mechanism base 26, forms a tonertight seal. A plastic bead, wire, or a vinyl type tubing have been found sufficient to form a seal when used in cooperation with the complementary recess 27 of the dispensing mechanism into which the container is joined. The recess 27 in the dispensing mechanism base 26 is undercut (as best seen in FIGS. 3 and 4) such that the joining member 32 expands into the recess creating the toner tight seal.

The dispensing roll 20 is rotatably supported in the dispensing mechanism base 26 in appropriate slots 29 and is held therein by the resiliency of the roll material 21 biasing the roller against the base 26 and precluding the movement of the roller through dispensing opening 28. A gear 23 is appropriately secured to shaft 22 to be operatively connected to any suitable drive means for rotating the dispensing roll at a predetennined speed to produce the desired dispensing rate.

Dispensing roll 20 comprises a material 21 having a cellular structure including small open cavities or cells capable of receiving and holding therein a substantially uniform quantity of toner powder. Typical examples of such materials which can be formed in an open-celled or foamed configuration are polyurethanes, polyvinlychloride, silicones, polystyrenes, styreneacrylonitriles, celluloseacetate, and phenolics or any other foamed elastomeric material having a textured opencelled surface. Foaming of these materials can be accomplished either by a mechanical frothing, a physical dissolving ofa gas or liquid within the resin material, or by chemically incorporating the foaming or blowing agent directly into the material to release an inert gas within the resin when the temperature is increased. This material is secured upon the shaft 22, as by glueing.

A typical resilient roll for use in the preferred embodiment of this invention is one fabricated of a urethane foam. The term resiliency, as herein used, is the property of the material upon being deformed to recover its original posture rapidly when the force of deformation is removed. It is found that by varying the ratio of raw materials and the foaming conditions, it is possible to produce a flexible foam having a broad spectrum of and properties. By properly choosing materials and controlling the formation of the cell-like structures, it is possible to form a foamed polyurethane dispensing roll as herein described having high tensile strength and extremely good resiliency.

The resilient dispensing roll 20 is rotatably supported within the dispensing base 26 to effect a movable seal capable of retaining toner material within the flaccid container 30. The dispensing roll 20 is placed through the opening 28 of the dispensing base 26 and secured therein by means of the resiliency of the material in interference with the

boss portions

36 and 46 of the base 26. The cellular material is thereby supported with the material slightly deformed by the boss or

lip portions

36 and 46 of the dispensing base 26. This biasing contact with the boss portions prevents toner powder from being discharged between the roll and the dispensing base and retains the roller in the base.

in operation, as the roller 20 is rotated the open cellular outer surface passes in contact with the particulate matter which is loaded into the open cellular structure and dispensed upon the continued rotation of the rolls as the cells containing the toner powder pass through the dispensing opening and into contact with the boss portion 36 prior to continuing into the dispensing base 26. The dispensing base 26 is formed with the

boss portions

36 and 46 extending on opposite sides of the opening 28 in the base member. These

portions

36 and 46 extend into interference with the normal path of rotation of the cellular structure to deform the roller inwardly sufficient to form a tonertight seal for the container 30.

As best shown in FIG. 5, there is illustrated the mechanical biasing of the roller 20 due to the interference of the

boss portions

36 and 46 of the dispensing base with the resilient material 21 of the dispensing roller. The individual cell-like cavities composing the peripheral surface of the roller 20 become loaded with toner particles as the roller is rotated through the quantity of material contained in the container 30 due to the individual cavities of the cellular structure scooping the toner into the cavities as the roller is rotated through the toner powder. Due to the resiliency of the material itself, this scooping action expands the cavities entrapping the toner powder in the cellular structure. Since the cavities are of a substantially uniform size, each individual cell is loaded with an approximately equal amount of toner and, therefore. evenly dispenses the toner material across the entire length of the roller 20. After becoming loaded with toner powder, the roller is rotated past the boss portion 36 through the dispenser face cavities as they pass from the mechanical biasing or wiping influence of the boss portion 36 and into the dispensing opening. This amount of toner is equally distributed across the roll surface and is uniformly dispensed to the developer mixture.

it has been found that an additional quantity of the toner powder is dispensed from the roller by the action of the cellularlike material coming into contact with the boss portion 46, positioned prior to the rollers again entering the container 30. It is thought that this dispensing action is due in effect to the squeegeeing of the toner material from the resilient dispensing roll due to the mechanical biasing of the roller material effected by the action of the leading edge of the boss portion 46. It is believed that the uniform dispensing of the toner material from the dispensing roll 20 occurs both as a result of the deformation of the material or wiping action by the boss portion 36 and subsequent restoration of the material to its original shape due to its resilient properties which mechanically expels the toner powder material contained within the cellularlike structure, and in addition, as the result of the compression of the cellularlike cavities by the squeegee action of the boss portion 46 which completed the emptying of the contents of each individual cell.

As the dispensing roller 20 is rotated to dispense the electroscopic toner powder into the developer mixture, it has been found that when utilizing certain electroscopic toner powder the material will bridge such that the dispensing roll 20 will remove the toner powder contacting the roll surface 21 and the bridging or agglomeration of the electroscopic toner powder above the roll surface will prevent additional powder from coming into contact with the roller to be dispensed from the container. An antibridging device 60 such as a roller or brush 60 extending substantially the length of roll 20 and having loosely spaced semirigid fibers 61 extending from a central axis 63, for example nylon bristles or any other semirigid or rigid material that will not chemically react with the contents of the container, is carried within the container 30 on the dispensing roller 20. The roller 60 is rotated in the container 30 by means of frictional contact between the dispensing roll 20 and the bristles 61 of the roller or brush 60. A pair of guides 62 are carried by the dispensing base 26 and extend between opposite sides of the base to constrain the roller adjacent to the dispensing roll 20.

In operation, as the dispensing roll 20 is rotated to dispense the particulate electroscopic toner material, the contact between the bristles 61 of the antibridging roller or brush 60 rotates the roller within the container 30 thereby preventing the agglomeration of the toner powder or bridging of the powder above the dispensing roll. The material of which the antibridging brush is fonned is of sufficient rigidity to prevent collapsing of the brush due to the weight of the electroscopic powder within the container 30 and forms a sufficiently open or loosely spaced structure to allow the toner powder to pass through the bristles to the dispensing roller. In addition, as best shown in FIG. 5, the guides 62 carried by the dispensing base 26 are positioned such that the antibridging brush may effect epicyclic or planetary movement about the dispensing roll 20 within a sector defined by the extremities 64 of the guides 62 thereby ensuring that bridged formation is prevented. This partial epicyclic action can be effected by the periodic reversal of the rotational direction of dispensing roller 20. Such reversal of direction is provided by coupling the drive gear 23 to a suitable reciprocal motion source in any well-known manner.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teaching of the invention without departing from its essential teachings.

What is claimed is: 1. Apparatus for dispensing a controlled amount of particulate material including a rotatable dispensing roller having an open-celled resilient peripheral surface for retaining particulate material therein,

a dispensing base rotatably supporting said dispensing roller and having boss portions defining a dispensing opening mechanically biasing said dispensing roller to defonn the open-celled peripheral surface thereof,

a receptacle for containing a quantity of particulate material therein carried by said dispensing base to present the particulate material therein to said rotatable dispensing roller,

means to rotate said dispensing roller through said dispensing opening to sequentially deform said opencelled peripheral surface to effect dispensing of the particulate material contained therein, and

a rotatable cylinder having semirigid openly spaced fibers extending radially from a central axis supported within said dispenser and rotatably driven by said dispensing roller to pass material between said fibers to said dispensing roller.

2. The apparatus of claim 1 wherein said rotatable cylinder having semirigid openly spaced fibers extending radially from a central axis supported within said dispenser is carried upon and rotatably driven in an epicyclic path of movement by said dispensing roller.

3. The apparatus of claim 2 wherein said rotatable cylinder having semirigid openly spaced fibers extending radially from a central axis supported within said dispenser is rotatably driven by frictional contact with said dispensing roller.

4. The apparatus of claim 3 wherein said boss portions compress said resilient surface prior to said surface passing through said dispensing opening to effect the discharge of the material contained therein during the return expansion of said surface, and

prior to said surface returning through said dispensing opening to effect discharge by the squeegeeing of the surface during the compression thereof.

Claims

1. Apparatus for dispensing a controlled amount of particulate material including a rotatable dispensing roller having an open-celled resilient peripheral surface for retaining particulate material therein, a dispensing base rotatably supporting said dispensing roller and having boss portions defining a dispensing opening mechanically biasing said dispensing roller to deform the opencelled peripheral surface thereof, a receptacle for containing a quantity of particulate material therein carried by said dispensing base to present the particulate material therein to said rotatable dispensing roller, means to rotate said dispensing roller through said dispensing opening to sequentially deform said open-celled peripheral surface to effect dispensing of the particulate material contained therein, and a rotatable cylinder having semirigid openly spaced fibers extending radially from a central axis supported within said dispenser and rotatably driven by said dispensing roller to pass material between said fibers to said dispensing roller.

4. The apparatus of claim 3 wherein said boss portions compress said resilient surface prior to said surface passing through said dispensing opening to effect the discharge of the material contained therein during the return expansion of said surface, and prior to said surface returning through said dispensing opening to effect discharge by the squeegeeing of the surface during the compression thereof.