Note: Descriptions are shown in the official language in which they were submitted.
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~ PARTICLl~ DISPEN~ N~ SYSTEM
This invention relates generally to an electrophotographic printing
machine, and more particularly concerns an improved particle dispensing
system for use therein.
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 docu-
ment. 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 triboelectricaUy thereto. This two-
component 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.
~arious 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 mate-
rial. 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. ~ereinbefore, toner
particles have been dispensed from a trough or hopper into the developer
35 material. ~requently, the toner particles are dispensed in a non-uniform
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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:
U.S. Patent No. 3,659,556
5Patentee: Mutschler
Issued: May 2,1972
U.S. Patent No. 4,142,655
Patentee: Fantuzzo
10Issued: March 6,1979
Japanese Lai~Open No. 50-29145
Applicant: Canon, Inc.
Application Date: July 11,1973
IBM Technical Disclosure Bulletin
Vol. 15, No. 4, September, 1972
Page 1262
By: Queener
Mutsc}ler 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.
Fantuzzo discloses a pair of flexible augers for transporting toner
25 particles from a remote container to a toner dispenser positioned adjacent the
development system.
The Japanese publication 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
30 particles to the developing unit.
Queener discloses a flexible auger for transporting toner particles
from a first station to a second station located within an office eopying
machine.
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Various aspects of this invention are as
follows:
An apparatus for furnishing toner particles
to a developer material in a housing, including:
means for storing a supply of toner particles;
an enclosure having an entrance aperture
for receiving toner particles from said storing means
and an exit aperture for dispensing toner particles to
said discharging means;
a stationary shaft disposed interiorly of
said enclosure;
a first helical member mounted rotatably on
said shaft;
means for rotating said first helical member
relative to said shaft to transport toner particles
received at the entrance aperture of said enclosure to
the exit aperture thereof;
a trough having an entrance port coupled -to
the exit aperture of said enclosure with a portion of
the entrance port of said trough being arranged to
receive developer material from the housing, said
trough having a sloping edge for discharging the received
toner particles and developer material to the remaining
developer material in the housing;
a second helical member mounted rotatably in
said trough; and
means for rotating said second helical member
relative to said trough 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.
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;
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a container storing a supply of toner particles
therein;
an enclosure having an entrance aperture Eor
receiving toner particles from said con-tainer and an
exit aperture for dispensing toner particles to said
discharging means;
a stationary shaft disposed interiorly of
said enclosure;
a first helical member mounted rotatably on
said shaft;
means for rotating said first helical member
relative to said shaft to transport toner particles
received at the entrance aperture of said enclosure to
7 the exit aperture thereof;
a trough having an entrance port coupled to
the exit aperture of said enclosure with a portion of
the entrance port of said trough being arranged to
receive developer material from said transporting
means, said trough having a sloping edge for discharging
the received toner particles and developer material to
the remaining developer material in the chamber of said
housing;
a second helical member mounted rotatably in
said trough; and
means for rotatin~ said second helical member
relative to said trough to move the received toner
particles and developer material therealong for discharge
over the sloping edge thereoE, to the remaining developer
material in the chamber of said housing.
Other aspects of the present invention will
become apparent as the following description proceeds
and upon reference to the drawings, in which:
Figure 1 is a schematic elevational view
illustrating an electrophotographic printing machine
incorporating the features of the present invention
therein;
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Figure 2 is a schematic elevational view
depicting the development system used in the Figure l
printing machine; and
Figure 3 is a fragmentary, side elevational
view of the particle dispenser used in the Figure 2
development system.
While the present invention will hereinafter
be described in connection with a preferred embodiment
thereof, it will be understood that it is not intended
to limit the invention to that embodiment. On the
contrary, it is intended to cover all alternatives,
modifications and equivalents as may be included within
the spirit and scope of the invention as defined by the
appended claims.
Inasmuch as the art of electrophotographic
printing is well known, the various processing stations
employed in the Figure 1 printing machine will be shown
hereinafter schematically and their operation described
briefly with reference thereto.
...~
Turning now 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 electrieally
grounded aluminum alloy. Other suitable photoconduetive surfaces and
conductive s~lbstrates may also be employed. Belt 10 moves in the direction of
arrow 16 to advance successive portions of photoeonductive surfaee 12 through
the various processing stations disposed about the path of movement thereof.
As shown, belt 10 is en-trained about a stripping roller 18, tension roller 20 and
10 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 arrow16. 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
15 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 referenee 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 photocon-
ductive 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 faeedown upon a transparent platen 30. Lamps 32
flash light rays onto original document 28. The light rays reflected frGm
original document 28 are transmitted through lens 34 forming a light image
30 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. There-
after, belt 10 advances the electrostatic latent image recorded on photocon-
35 ductive surface 12 to development station C.
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At development stat;on 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 photoeon-
ductive surface 12. Magnetic brush development system 36 includes a
developer roller 38 which advances the developer material into contact ~Nith
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 o-f
10 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 sta$ion D, a sheet of support material 40 is
moved into contact with the toner powder image. The sheet of support
15 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
20 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
25 continues to move in the direction of arrow 52 onto a conveyor (not shown)
which advances the sheet to fusing station ~.
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
30 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.
In this manner, the toner powder image is permanently affixed to sheet 40.
After fusing, chute 60 guides the advancing sheet ~0 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
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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 6~ in
contact with photoconductive surface 12. The pre-clean corona generating
5 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. Subsecluent 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
10 for the next successive imaging eycle.
It is believed that the foregoing description is sufficient for
purposes of the present application to illustrate the general operation of an
electrophoto~raphic printing machine incorporating the features of the present
invention therein.
Referring now to ~igure 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
20 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
25 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
30 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
35 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,
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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 material and toner
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. ~hafts 92 are
supported in bearings 94 mounted in the lower portion of hopper 80. C)ne 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. ~elical 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. ~haft 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 ~6. In
addition, entrance port 100 receives developer material and denuded carrier
granules from tubular member 66 (Figure 2). This mixture of material is
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intermingled ~nd advanced by auger ~6 so as to be dispensed substantially
unieormly therefrom into chamber 72 of housing 74 for replenishing the toner
particles of the developer material contained therein. Auger 7~ includes a
shaft 114 having a helical member 116 secured thereto. Alternatively, shaft 114
S may be omitted in lieu of a helical coil spring which may be used for auger 76.
~Ielical member 116 is disposed interiorly of tubular member 112. Rearings 118
support shaft 11~ in frame 120. ~ear 122 is mounted on shaft 114 and meshes
with gear 110. Motor 124 rotates shaft llA 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
10 well 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 OI toner
15 particles to exit 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
20 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 dispensingof toner particles along the length of trough 112. This maintains the
concentration of toner particles within the developer material substantially
25 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. However3
actuation of motor 124 is initiated when the print button of the printing
30 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. ~urthermore, the
carrier granules tend to minimize jamming and clogging of the toner par~icles
35 as they are being advanced.
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One skilled in the art will appreciate 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
5 zone and a different pitch and diameter in the toner transport and dispense
zone. In addition to facilitating the advancement of the toner particles durin~
the dispensing operation, the intermingling of the carrie~ granules therewith
premixes the developer material prior to the dispensing thereof into the
chamber of the housing storing the main supply of developer material.
In recapitulation, it is clear that the dispensing apparatus of 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 reeeived 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 inter-
mingling with the remaining developer material. In this manner, premixing of
the developer material is achieved and the flowability of the toner particles
greatly enhanced.
It is, therefore, evident that there has been provided, in accor-
dance with the present invention, an apparatus for dispensing toner particles
that fully satisfies the aims and advantages hereinbefore set eorth. While this
invention has been described in conjunction with a specific embodiment
thereof, it is evident that many alternatives, modifications and variatior.s will
be apparent to those skilled in the art. Accordingly, it is intended to embrace
all such alternatives, modifications and variations as fall within the spirit and
broad scope of the appended claims.
