PARTICLE DISPENSING APPARATUS

Abstract: An apparatus for furnishing toner particles to a develop­ er material in a housing (74). The apparatus intermingles (at 76) a portion of the developer material with the toner particles from a store (80) and dispenses the resultant mixture into the developer material remaining in the housing (74).

Description: PARTICLE DISPENSING APPARATUS This invention relates particle dispensing apparatus for furnishing toner particles to a developer material in a housing,which apparatus is particularly suitable for use in an electrophotographic printing machine. Generally, the process of electrophotographic printing includes charging a photoconductive member to a substantially uniform potential to sensitize the surface thereof. The charged portion of the photoconductive member is exposed to a light image of an original document being reproduced. This records an electrostatic latent image on the photoconductive member corresponding to the informational areas contained within the original document. After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed by bringing a developer material into contact therewith. This forms a powder image on the photoconductive member which is subsequently transferred to a copy sheet. Finally, the powder image is heated to permanently affix it to the copy sheet in image configuration. A suitable developer material frequently comprises carrier granules having toner particles adhering triboelectrically thereto. This twocomponent mixture is brought into contact with the photoconductive surface. The toner particles are attracted from the carrier granules to the latent image. These toner particles adhere to the latent image so as to form a powder image on the photoconductive surface. Various methods have been devised for applying developer material to the latent image. For example, the developer material may be cascaded over the latent image with the toner particles being attracted from the carrier granules thereto. Other techniques utilize magnetic field producing devices which form brush-like tufts extending outwardly therefrom contacting the photoconductive surface. In any system, it is apparent that during the development process, toner particles are depleted from the developer material. Thus, additional toner particles must be furnished to maintain copy density at a substantially optimum level. In order to produce an efficient printing machine, it is necessary to conveniently and effectively replace the toner particles used during the formation of the copies. Hereinbefore, toner particles have been dispensed from a trough or hopper into the developer material. Frequently, the toner particles are dispensed in a non-uniform manner. Variations in toner particle dispensing may effect the resultant copy quality. Various approaches have been devised to dispense toner particles from a hopper. The following disclosures appear to be relevant: US-A-3659556 describes a development system in which toner particles are dispensed into a developer material. An auger drive system transports the developer material to a donor roll. US-A-4142655 discloses a pair of flexible augers for transporting toner particles from a remote container to a toner dispenser positioned adjacent the development system. Japanese laid-open publication No. 50-29145 describes a toner container having a rotary driven vaned member located in the opening thereof for dispensing toner particles into a supply passage. A screw conveyor moves the toner particles to the developing unit. IBM Technical Disclosure Bulletin, Volume 15, No. 4, September 1972, Page 1262, discloses a flexible auger for transporting toner particles from a first station to a second station located within an office copying machine. Particle dispensing apparatus according to this invention is characterised by means for receiving toner particles from the storing means and a portion of the developer material from the housing, for intermingling the received toner particles and developer material with one another and advancing the received toner particles and developer material to the developer material remaining in the housing. The present invention also provides an apparatus for developing an electrostatic latent image recorded on a photoconductive member, including a housing defining a chamber for storing a supply of developer material therein, means, disposed in the chamber of the housing, for transporting developer material into contact with the photoconductive member to develop the electrostatic latent image recorded thereon, and particle dispensing apparatus as described above for furnishing toner particles to developer material in said chamber. In order that the present invention may be more readily understood, reference will now be made to the accompanying drawings, in which: Figure 1 is a schematic elevational view illustrating an electrophotographic printing machine incorporating particle dispensing apparatus of the present invention therein; Figure 2 is a schematic elevational view depicting the development system used in the Figure I printing machine; and Figure 3 is a fragmentary, side elevational view of the particle dispenser used in the Figure 2 development system. Referring to Figure 1, the electrophotographic printing machine employs a belt 10 having a photoconductive surface 12 deposited on a conductive substrate. Preferably, photoconductive surface 12 is made from a selenium alloy with conductive substrate 14 being made from an electrically grounded sluminum alloy. Other suitable photoconductive surfaces and conductive substrates may also be employed. Belt 10 moves in the direction of arrow 16 to advance successive portions of photoconductive surface 12 through the various processing stations disposed about the path of movement thereof. As shown, belt 1D is entrained about a stripping roller 18, tension roller 20 and drive roller 22. Drive roller 22 is mounted rotatably and in engagement with belt 10. Motor 24 rotates roller 22 to advance belt 10 in the direction of arrow 16. Roller 22 is coupled to motor 24 by suitable means such as a drive belt. Drive roller 22 includes a pair of opposed spaced edge guides. The edge guides define a space therebetween which determines the desired path of movement of belt 10. Belt 10 is maintained in tension by a pair of springs (not shown) resiliently urging tension roller 20 against belt 10 with the desired spring force. Both stripping roller 18 and tension roller 20 are mounted rotatably. These rollers are idlers which rotate freely as belt 10 moves in the direction of arrow 16. With continued reference to Figure 1, initially a portion of belt 10 passes through charging station A. At charging station A, a corona generating device, indicated generally by the reference numeral 26, charges photoconductive surface 12 of belt 10 to a relatively high, substantially uniform potential. Next, the charged portion of photoconductive surface 12 is advanced through exposure station B. At exposure station B, an original document 28 is positioned facedown upon a transparent platen 30. Lamps 32 flash light rays onto original document 28. The light rays reflected from original document 28 are transmitted through lens 34 forming a light image thereof. Lens 34 focuses the light image onto the charged portion of photoconductive surface 12 to selectively dissipate the charge thereon. This records an electrostatic latent image corresponding to the informational areas contained within the original document on photoconductive surface 12. Thereafter, belt 10 advances the electrostatic latent image recorded on photoconductive surface 12 to development station C. At development station C, a magnetic brush development system, indicated generally by the reference numeral 36, transports a developer material of carrier granules and toner particles into contact with photoconductive surface 12. Magnetic brush development system 36 includes a developer roller 38 which advances the developer material into contact with photoconductive surface 12. The developer roller forms a brush comprising carrier granules and toner particles. The toner particles are attracted from the carrier granules to the electrostatic latent image forming a toner powder image on photoconductive surface 12 of belt 10. The detailed structure of magnetic brush development system 36 will be described hereinafter with reference to Figure 2. After development, belt 10 advances the toner powder image to transfer station D. At transfer station D, a sheet of support material 40 is moved into contact with the toner powder image. The sheet of support material is advanced to transfer station D by a sheet feeding apparatus 42. Preferably, sheet feeding apparatus 42 includes a feed roll 44 contacting the uppermost sheet of stack 46. Feed roll 44 rotates to advance the uppermost sheet from stack 46 into chute 48. Chute 48 directs the advancing sheet of support material into contact with photoconductive surface 12 of belt 10 in a timed sequence so that the toner powder image developed thereon contacts the advancing sheet of support material at transfer station D. Transfer station D includes corona generating device 50 which sprays ions onto the backside of sheet 40. This attracts the toner powder image from photoconductive surface 12 to sheet 40. After transfer, the sheet continues to move in the direction of arrow 52 onto a conveyor (not shown) which advances the sheet to fusing station E. Fusing station E includes a fuser assembly, indicated generally by the reference numeral 54, which permanently affixes the transfered toner powder image to sheet 40. Preferably, fuser assembly 54 includes a heated fuser roller 56 and a back up roller 58. Sheet 40 passes between fuser roller 56 and back up roller 58 with the toner powder image contacting fuser roller 56. Ir, this manner, the toner powder image is permanently affixed to sheet 40. After fusing, chute 60 guides the advancing sheet 40 to catch tray 62 for subsequent removal from the printing machine by the operator. Invariably, after the sheet of support material is separated from photoconductive surface 12 of belt 10, some residual particles remain adhering thereto. These residual particles are removed from photoconductive surface 12 at cleaning station F. Cleaning station F includes a pre-clean corona generating device (not shown) and a rotatably mounted fibrous brush 64 in contact with photoconductive surface 12. The pie-clean corona gelleráting device neutralizes the charge attracting the particles to the photoconductive surface. These particles are then cleaned from photoconductive surface 12 by the rotation of brush 64 in contact therewith. Subsequent to cleaning, a discharge lamp (not shown) floods photoconductive surface 12 with light to dissipate any residual charge remaining thereon prior to the charging thereof for the next successive imaging cycle. Referring now to Figure 2, there is shown development system 36 in greater detail. As depicted thereat, development system 36 includes a developer roller 38 having a non-magnetic tubular member 66. An elongated magnetic member 68 is positioned interiorly of tubular member 66 and spaced from the interior periphery thereof. Tubular member 66 rotates in the direction of arrow 70 so as to advance the developer material into contact with the electrostatic latent image recorded on photoconductive surface 12 of belt 10. Magnetic member 68 has a plurality of magnetic poles impressed about a portion thereof. Thus, as tubular member 66 rotates in the direction of arrow 70, it passes through the developer material in chamber 72 of housing 74. Developer material disposed in chamber 72 is attracted to tubular member 66 via the magnetic field generated by elongated magnetic member 68. In this manner, the developer material is attracted to tubular member 66 and advances therewith into contact with the electrostatic latent image recorded on photoconductive surface 12 of belt 10. The electrostatic latent image attracts some toner particles from the developer material. Thus, toner particles are being continually depleted from the developer material. If additional toner particles were not furnished to the development material, eventually the copies would become progressively lighter and degradated in quality. The denuded development material advances with tubular member 66 in the direction of arrow 70 until the magnetic field produced by elongated magnetic member 68 no longer attracts the material thereto. At this time, the denuded developer material falls freely from tubular member 66. Some of the developer material passes into auger 76 of the toner dispenser, indicated generally by the reference numeral 78. Toner dispenser 78 includes a hopper 80 storing a supply of toner particles in chamber 82. The lower end portion of chamber 82 has an opening with auger 84 being positioned thereat. Auger 84 meters precise quantities of toner particles from chamber 82 of hopper 80. The toner particles are advanced to auger 76 which intermingles developer material and denuded carrier granules with the toner particles. Auger 76 substantially uniformly dispenses the mixture of developer maternal and tci.=r particles into chamber 72 of housing 74 to maintain the concentration of toner particles within the developer material substantially constant. Agitator 88 positioned in chamber 82 of housing 80 rotates to prevent bridging and caking of the toner particles therein. By way of example, elongated magnetic member 68 is a cylindrical member being made preferably from barrium ferrite having a plurality of magnetic poles impressed about a portion of the circumferential surface thereof. Tubular member 66 is made preferably from aluminum having the exterior circumferential surface thereof roughened. Turning now to Figure 3, there is shown the detailed structure of toner dispenser 78. As shown thereat, agitator 88 comprises a rectangular frame 90 having shafts 92 extending outwardly therefrom. Shafts 92 are supported in bearings 94 mounted in the lower portion of hopper 80. One shaft has a gear 96 secured thereto. Auger 84 includes an enclosure 86 having an entrance port 98 disposed in the opening of hopper 80 so as to receive toner particles being discharged from chamber 82. Enclosure 86 also has an exit port 100 for discharging a precisely metered quantity of toner particles into auger 76. Auger 84 includes a stationary shaft 102 extending in a longitudinal direction interiorly of enclosure 86. Helical member 104 is entrained about stationary shaft 102 and is adapted to rotate relative thereto. One end of helical member 104 is secured to shaft 106. Shaft 106 is supported in bearings 108 mounted in enclosure 86. Gear 110 is secured to shaft 106 and meshes with gear 96. Auger 76 includes a trough 112 having an entrance port 113 coupled to exit port 100 of auger 84. Thus, toner particles being metered from chamber 82 of hopper 80 are advanced along auger 84 and metered to auger 76. In addition, entrance port 100 receives developer material and denuded carrier granules from tubular member 66 (Figure 2). This mixture of material is intermingled and advanced by auger 76 so as to be dispensed substantially uniformly therefrom into chamber 72 of housing 74 for replenishing the toner particles of the developer material contained therein. Auger 76 includes a shaft 114 having a helical member 116 secured thereto. Alternatively, shaft 114 may be omitted in lieu of a helical coil spring which may be used for auger 76. Helical member 116 is disposed interiorly of tubular member 112. Bearings 118 support shaft 114 in frame 120. Gear 122 is mounted on shaft 114 and meshes with gear 110. Motor 124 rotates shaft 114 and, in turn, gear 122. In this way, gears 110 and 96 are also driven so as to rotate helical members 116 and 104 as çzell as rectangular frame 90. In operation, toner particles in chamber 82 of hopper 80 are continuously agitated by the rotation of frame 90. These toner particles descend through the opening in hopper 80 into entrance port 98 of enclosure 86. Helical member 104 meters and advances precise quantities of toner particles to e)tit port 100. The toner particles then fall from exit port 100 into entrance port 113 of trough 112. Entrance port 113 also receives developer material from tubular member 66. This combination of materials is advanced by helical member 116 along trough 112 so as to be discharged over the downward sloped edge 126 of trough 112. Inasmuch as trough 112 extends across chamber 72 of housing 74, the combination of toner particles and carrier granules is dispensed substantially uniformly over front edge 126. The slope of edge 126 of trough 112 is shaped to provide for substantially uniform dispensing of toner particles along the length of trough 112. This maintains the concentration of toner particles within the developer material substantially constant. In normal operation, motor 124 is continuously energized so as to continuously dispense toner particles into the chamber of the developer housing. The dispensing rate corresponds with the usage rate. However, actuation of motor 124 is initiated when the print button of the printing machine is depressed. The intermingling of toner particles with carrier granules and developer material greatly facilitates the uniformity of dispensing. The carrier granules aid in the movement of the toner particles. Furthermore, the carrier granules tend to minimize jamming and clogging of the toner particles as they are being advanced. It will be appreciated that a pair of auger systems are not necessarily required and that a single shaft auger system having different outer and inner diameters and pitches may be employed in lieu thereof. Thus, there would be one pitch and diameter in the toner metering zone and a different pitch and diameter in the toner transport and dispense zone. addition to facilitating the advancement of the toner particles during the dispensing operation, the intermingling of the carrier granules therewith premixes the developer material prior to the dispensing thereof into tWe hamper of the hous r;9 storing the main supply of developer material. In recapitulation, it is clear that the dispensing apparatus 0 the present invention includes a hopper storing a supply of toner particles therein and an auger for metering precise quantities of toner particles therefrom. The auger advances the toner particles into a dispensing auger which intermingles a small quantity of developer material received from the developer roller with the toner particles. This mixture is then advanced so as to be discharged substantially uniformly into the chamber of the developer housing for intermingling with the remaining developer material. In this manner, premixing of the developer material is achieved and the flowability of the toner particles greatly enhanced.

Claims: CLAIMS: l. Particle dispensing apparatus for furnishing toner particles to a developer material in a housing (74), including means (80) for storing a supply of toner particles; and characterised by means (76) for receiving toner particles from said storing means (80) and a portion of the developer material from the housing (74), for intermingling the received toner particles and developer material with one another and advancing the received toner particles and developer material to the developer material remaining in the housing (74). 2. Apparatus according to claim 1, wherein said intermingling and advancing means (76) includes: means (76) for discharging the received toner particles and developer material into the remaining developer material in the housing (74); and means (84) for transporting (80) toner particles from said storing means to said discharging means (76). 3. Apparatus according to claim 2, wherein said transporting means (84) includes: an enclosure (86) having an entrance aperture (98) for receiving toner particles from said storing means (80) and an exit aperture (100) for dispensing toner particles to said discharging means (76); a stationary shaft (102) disposed interiorly of said enclosure (86); a helical member (104) mounted rotatably on said shaft (102); and means (106) for rotating said helical member (104) relative (102) to said shaft (102) to transport toner particles received at the entrance aperture (98) of said enclosure to (100) the exit aperture thereof. 4. Aapparatus according to claim 3, wherein said discharging means (76) includes: a trough (112) having an entrance port (113) coupled to the exit aperture (100) of said enclosure (86) with a portion of the entrance port (113) of said trough (112) being arranged to receive developer material from the housing (74), said trough (112) having a sloping edge for discharging the received toner particles and developer material to the remaining developer material in the housing (74); a helical member (116) mounted rotatably in said trough (112); and means (114) for rotating said helical member (116) relative to said trough (112) to move the received toner particles and developer material therealong for discharge over the sloping edge thereof to the remaining developer material in the housing (74). 5. Apparatus according to claims 1, 2 or 4, further including means (90), operatively associated with said storing means (8C), for agitating the t@ner particles therein to facilitate dispensing therefrom. 6. Apparatus for developing an electrostatic latent image recorded on a photoconductive member, including: a housing defining a chamber for storing a supply of developer material therein; means, disposed in the chamber of said housing, for transporting developer material into contact with the photoconductive member to develop the electrostatic latent image recorded thereon; and particle dispensing apparatus according to any preceding claim for furnishing toner particles to developer material in said chamber.

Inventors: POEHLEIN, RAYMOND E.
Applicants: XEROX CORPORATION
Application year: 1982
Main classification: G03G15
IPC codes: G03G15