U.S. patent number 3,600,083 [Application Number 04/799,391] was granted by the patent office on 1971-08-17 for electrostatic printing system employing a replaceable cartridge to provide a supply of a recording element and processing means therefor.
This patent grant is currently assigned to RCA Corporation. Invention is credited to Marvin A. Leedom.
United States Patent |
3,600,083 |
Leedom |
August 17, 1971 |
ELECTROSTATIC PRINTING SYSTEM EMPLOYING A REPLACEABLE CARTRIDGE TO
PROVIDE A SUPPLY OF A RECORDING ELEMENT AND PROCESSING MEANS
THEREFOR
Abstract
A replaceable cartridge, adapted to be removably installed in an
electrostatic printing system, provides a supply of a recording
element and charging, developing, and cutting means therefor. Means
are provided to convey and to guide the recording element through
the cartridge along a path including charging, image exposing,
developing, and cutting stations.
Inventors: |
Leedom; Marvin A. (Warminster,
PA) |
Assignee: |
RCA Corporation (N/A)
|
Family
ID: |
25175790 |
Appl.
No.: |
04/799,391 |
Filed: |
February 14, 1969 |
Current U.S.
Class: |
399/111;
399/385 |
Current CPC
Class: |
G03G
15/28 (20130101); G03G 15/26 (20130101) |
Current International
Class: |
G03G
15/26 (20060101); G03G 15/28 (20060101); G03G
15/00 (20060101); G03g 013/10 () |
Field of
Search: |
;355/3,10,13,16,4,6,7,10--12 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Matthews; Samuel S.
Assistant Examiner: Bero; E. M.
Claims
I claim:
1. A replaceable cartridge for an electrostatic printing system of
the type wherein a recording element is moved, by drive means
disposed in said system and external to said replaceable cartridge
along a continuous path through said cartridge, said path including
at least an image exposing station and a developing station, said
cartridge comprising:
a storage section comprising means to store a supply of said
recording element,
guide means disposed in said cartridge and engageable with said
recording element and said drive means for cooperating therewith to
guide and to move said recording element along said path only when
said cartridge is installed in said system, whereby charge patterns
can be formed on said recording element at said image exposing
station,
said drive means being separate and detached from said recording
element and said guide means when said cartridge is removed from
said system, and
a developer section comprising means to develop said charge
patterns at said developing station.
2. A replaceable cartridge as described in claim 1, wherein
said path through said cartridge comprises, in addition, a charging
station,
a portion of said path including said charging station being in
said storage section,
a wire disposed in said storage section adjacent said charging
station,
a source of voltage disposed in said system but external to said
cartridge, and
means on said cartridge and connected to said wire for applying
said source of voltage to said cartridge only when said cartridge
is installed in said system, whereby to cause a corona discharge
about said wire to charge said recording element at said charging
station.
3. A replaceable cartridge as described in claim 1, said path
through said cartridge including, in addition, a cutting station
located past said developing station, and
said cartridge comprising, in addition,
cutting means disposed between said storage section and said
developer section for cutting said recording element at said
cutting station after said recording element has been
developed.
4. A replaceable cartridge as described in claim 1, said path
through said cartridge including, in addition, a charging station
and a cutting station,
said storage section including said charging station and having a
wire adjacent to said charging station for providing a corona
discharge at said charging station,
said cutting station being located along said path, past said
developing station and between said storage section and said
developer section, and
cutting means disposed between said storage section and said
developer section to cut said recording element at said cutting
station after said recording element has been developed.
5. A replaceable cartridge for an electrostatic printing system
comprising:
a developer section, and a recording-element storage section
disposed on, and removably fastened to, said developer section,
said storage section comprising a compartment for a recording
element,
said developer section comprising a reservoir compartment for a
liquid developer and pump means disposed in said cartridge for
pumping, when actuated, said liquid developer to said recording
element, and
said pump means comprising means to couple power drive means
disposed in said system and external to said cartridge to said pump
means to actuate said pump means only when said cartridge is
installed in said system.
6. A replaceable cartridge as described in claim 5, comprising, in
addition:
at least one roller being disposed in said storage section for
guiding said recording element along a processing path,
said storage section having a rear wall with an opening therein
adjacent said roller, whereby to expose a portion of said recording
element for providing charge patterns thereon, and
said processing path of said recording element extending between
said storage and said developer sections.
7. In an electrostatic printing system of the type wherein a
recording element is moved along a continuous path, through said
cartridge, including a charging station, an exposing station, and a
developing station, the improvement comprising, in combination:
a replaceable cartridge adapted to be removably installed in said
system,
said cartridge having a storage section for storing a supply of
said recording element,
said cartridge including said path and said stations,
drive means in said system, external to said cartridge, adapted to
engage said recording element, for moving it along said path, only
when said cartridge is installed in said system,
exposure means in said system adapted to expose said recording
element to provide charge patterns thereon at said exposure station
only when said cartridge is installed in said system,
said cartridge having a developer section for developer and means,
when actuated, for developing said charge patterns on said
recording element, and
said drive means being adapted to be coupled to said means for
developing said charge patterns only when said cartridge is
installed in said system.
8. In an electrostatic printing system of the type described in
claim 7, said combination comprising, in addition:
charging means disposed in said storage section of said cartridge
for charging said recording element when energized from an energy
source in said system and external to said cartridge.
Description
BACKGROUND OF INVENTION
This invention relates generally to an electrostatic printing
system employing a replaceable cartridge to provide a supply of a
recording element and processing means therefor. More particularly,
the invention relates to a replaceable cartridge adapted to be
removably installed in an electrostatic system of the type
providing electrostatic charge patterns on an electrically
insulating surface of a recording element. The replaceable
cartridge is particularly useful for providing a replenishing
supply of a recording element and processing means therefor in an
electrophotographic printing system wherein charge patterns are
formed on a previously uniformly charged recording element by
exposing the uniformly charged recording element with light images
from a cathode-ray tube.
In most prior art electrophotographic printing systems of the type
wherein a recording element is moved sequentially along a path to
electrostatic charging, image exposing, developing and cutting
stations, it is customary to include all of the recording-element
processing and conveying means in one relatively large housing or
cabinet. Such prior art apparatus requires periodic servicing. For
example, a relatively thin wire that is used for electrostatic
charging usually gets dirty, arcs, and may break with use. Where
liquid toners are used for developing, the recording element guide
means may become coated with developer and require periodic
cleaning. The cutting means get dull with use and must either be
replaced with new blades or sharpened. Where pumps are used for
conveying liquid developers, the pump seals tend to become dry,
causing the developer to leak through, and the developer reservoir
requires periodic cleaning. Also the supply of the recording
element has to be replenished periodically. Most of the
aforementioned servicing requires the services of skilled personnel
and takes the apparatus out of use during the servicing.
The aforementioned disadvantages of the prior art apparatus are
substantially overcome by the replaceable cartridge of the present
invention in that each replaceable cartridge provides a fresh
supply of the recording element and either new or reserviced
charging, developing, and cutting means. Thus, a new or reserviced
replaceable cartridge can be used to replace an exhausted one, and
the latter can be either discarded or reserviced at will, thereby
eliminating the servicing and down time of the electrostatic
printing system.
SUMMARY OF INVENTION
A replaceable cartridge is adapted to be removably installed in an
electrostatic printing system of a type wherein a recording element
is moved along a path including at least an exposing station and a
developing station. The replaceable cartridge has means to hold a
supply of the recording element and developer therefor, and
includes the aforementioned path and stations.
In one embodiment, the replaceable cartridge comprises an
electrostatic charging station, an image exposing station, a
developing station, a cutting station, and means for processing the
recording element at these stations. The replaceable cartridge has
the advantage of providing a replenishing supply of the recording
element, fresh charging means, fresh developing means, and sharp
cutting means in one unit which, when exhausted or inoperative for
any reason, can be replaced with a similar cartridge. The exhausted
replaceable cartridge can be serviced and replenished for
reuse.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a perspective view of an embodiment of the replaceable
cartridge, viewed from the top, front, and right side, the top
cover being cut away;
FIG. 2 is a rear view of the replaceable cartridge, disposed
against drive means (not a part of the replaceable cartridge) for
moving the recording element, some parts of the cartridge being
broken away;
FIG. 3 is a top view of the replaceable cartridge, showing the
recording-element drive means, cutter drive means, and pump drive
means, the replaceable cartridge being disposed against a
cathode-ray tube for receiving light images therefrom;
FIG. 4 is a fragmentary, cross-sectional view of the replaceable
cartridge and cathode-ray tube, taken along the line 4-4 in FIG. 3,
showing the recording-element drive means;
FIG. 5 is a top view of the lower developer section of the
replaceable cartridge with the upper recording-element storage
section of the replaceable cartridge removed;
FIG. 6 is a cross-sectional view of the replaceable cartridge,
taken along the line 6-6 of FIG. 5, showing the removable cartridge
positioned against a cathode-ray tube for receiving light images
therefrom; and
FIG. 7 is a cross-sectional view of the removable cartridge taken
along the line 7-7 of FIG. 5.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIG. 1 of the drawing, there is shown a
replaceable cartridge 10 comprising a lower developer section 12
and an upper recording-element storage section 14 disposed on the
developer section 12 and secured to the latter by any suitable
means, such as screws 16 and 18 (FIG. 5). The two sections 12 and
14 are separable from each other to facilitate both the
construction of the cartridge 10 and its servicing when necessary.
The cartridge 10 is of substantially rectangular cross section,
both horizontally and vertically, having a front wall 20, a rear
wall 22, a floor 23, a pair of right and left sidewalls 24 and 26,
respectively, and a removable top cover 27. The cartridge 10 is
constructed preferably of plastic sheet material that is relatively
opaque to light or is painted to provide a relatively light-tight
container.
Referring now to FIGS. 2 and 6, there is shown a supply roll 28 of
a web of a recording element 30 of the type used in an
electrophotographic printing system. In FIG. 6, the web of the
recording element 30 is shown defining a path through which it is
moved. The path includes a charging station 32, an image exposing
station 34, a developing station 36, and a cutting station 38 for
processing the recording element 30 in a process of printing
information derived from light images on a thin-window, cathode-ray
tube 40. The cathode-ray tube 40 is adapted to cooperate with the
cartridge 10, as shown in FIGS. 3, 4, and 6. It is within the
contemplation of the invention, however, to provide electrostatic
charge patterns on the recording element at the image exposing
station by means other than the cathode-ray tube 40.
The recording element 30 comprises, for example, a web of
relatively electrically conductive paper, having a resistivity
preferably between 10.sup.3 ohm-cm. and 10.sup.7 ohm-cm., coated
with a thin, relatively electrically insulating layer (not shown)
of photoconductive zinc oxide in a resin binder, in a manner well
known in the electrophotographic printing art. The photoconductive
zinc oxide layer of the recording element 30 is disposed against
the face 42 of the cathode-ray tube 40. A thin sheet of a
transparent plastic material (not shown) may be disposed between
the face 42 of the cathode-ray tube 40 and the recording element 30
to prevent frictional wear of the tube 40, if necessary.
The supply roll 28 of the recording element 30 is disposed within a
compartment 44 in the storage section 14 of the cartridge 10, as by
supporting the supply roll 28 by a mandrel 46 whose ends are
disposed in inner slots 48 and 50 in the pair of right and left
sidewalls 24 and 26, respectively, as shown in FIG. 1 and 2. The
web of the recording element 30 is threaded initially along the
path, within the cartridge 10, including the charging station 32,
the image exposing station 34, the developing station 36, and the
cutting station 38. The recording element 30 emerges from the
cartridge 10 through a slot 52 in the front wall 20 between the
sections 12 and 14, as shown in FIGS. 1, 6, and 7. For example, as
shown in FIG. 6, the web of the recording element 30 is threaded in
a path leading from the supply roll 28, then under a guide roller
54, over roller means, such as a pair of metal rollers 56 and 58,
between the top of the lower developer section 12 and the bottom of
the upper storage section 14, and finally out through the
relatively narrow slot 52 in the front wall 20.
The rollers 54, 56, and 58 are parallel to each other and are
journaled for free rotation in bearings in the sidewalls 24 and 26
of the cartridge 10. The rollers 54, 56, and 58 comprise guide
means for guiding the recording element 30 along its path to its
aforementioned processing stations. Also the roller 56 comprises
part of the charging means, and the rollers 56 and 58 comprise part
of the image exposing means, as will hereinafter be described in
detail.
Electrode means within the cartridge 10 is provided to
electrostatically charge the insulating (photoconductive layer)
surface of the recording element. To this end, there is provided a
relatively thin wire 60, of about 4 mils diameter, disposed within
the compartment 44, between the sidewalls 24 and 26, and parallel
to, and slightly above, the roller 56 with which it cooperates to
provide a corona discharge. The ends of the wire 60 are secured to
lugs 62 and 64 on the sidewalls 24 and 26, respectively, for
connection to a source of voltage (not shown) of sufficient
amplitude (about 6,000 volts DC) to provide the wire 60 with a
corona discharge of desired polarity between the roller 56 and the
wire 60, whereby to charge the surface of the recording element 30
uniformly as it is moved past the charging station 32. The metal
roller 56 is also adapted to be connected to the aforementioned
source of voltage and comprises a portion of the electrode means
for charging the recording element 30.
The rear wall 22 of the cartridge 10 is formed with an opening 66
to permit the thin-window, cathode-ray tube 40 to substantially
contact the charged recording element 30 at the exposing station
34, as shown in FIG. 6. When the uniformly charged recording
element 30, disposed over (usually grounded) rollers 56 and 58, is
exposed by light images from the cathode-ray tube 40, electrostatic
latent images are formed thereon in a manner well known in the art.
These latent images are developed at the developing station 36
(FIG. 7) by liquid developer 68 within the lower developer section
12 of the cartridge 10, in a manner to be hereinafter described in
detail.
After the recording element 30, with the developed information
thereon, is moved through the slot 52 in the cartridge 10, a
portion of the developed recording element 30 may be cut off by
actuating a cutter 70 at the cutting station 38, in a manner also
hereinafter to be described in detail.
Recording-element drive means, external to the replaceable
cartridge 10 and not a part thereof, are employed to move the
recording element 30 along the path including the charging station
32, the image exposing station 34, the developing station 36, and
the cutting station 38. The external recording-element drive means
comprise a pair of parallel, spaced-apart, first-class levers 72
and 74 disposed to receive the cartridge 10 between them, as shown
in FIG. 3. The levers 72 and 74 are pivoted about separate pins 76
and 78, supported by parallel, vertical members 80 and 82,
respectively, as shown in FIG. 3. The rear ends of the levers 72
and 74 are biased downwardly by springs 84 and 86, respectively, as
shown in FIGS. 3 and 4.
A shaft 88, adapted to be rotated by a motor 90, is journaled in
the levers 72 and 74 adjacent the front ends thereof, and gears 92
and 94 are fastened to the shaft 88, adjacent opposite ends
thereof, for rotation therewith, as shown in FIG. 3. A pair of
gears 96 and 98, disposed to mesh with the gears 92 and 94, are
fixed on ends of separate short shafts 100 and 102, respectively.
The short shafts 100 and 102 are also journaled in the proximal
ends of the levers 72 and 74, respectively. A pair of rubber drive
wheels 104 and 106 are fixed to the other ends of the shafts 100
and 102, respectively, for rotation therewith. With this
arrangement, the recording element 30 can be moved along its
processing path by merely positioning the cartridge 10 so that the
lateral, parallel, opposite edges of the recording element 30 are
disposed between the rubber drive wheels 104 and 106 and the idler
roller 58 of the cartridge 10. Hence, when thus positioned,
energizing the motor 90 causes the recording element 30 to unwind
from the supply roll 28 and move through its processing path,
within the cartridge 10, and out through the elongated slot 52. The
recording-element drive means are not part of the replaceable
cartridge 10, and it is within the contemplation of the present
invention to employ drive means other than those described above.
The cathode-ray tube 40 is also disposed between the levers 72 and
74 so that the horizontal center of the tube 40, which is the image
forming portion thereof, can be positioned adjacent the image
exposing station 34 of the cartridge 10.
The cartridge 10 is formed with guide means adjacent the floor 23
thereof so that it can be correctly anchored in an
electrophotographic system to receive the light images from the
cathode-ray tube 40 and the drive means for moving the recording
element 30. For example, a plurality of parallel bar guides 108,
110, 112, and 114 extend downwardly to the floor 23 of the
cartridge 10, and a pin 116 is disposed between the parallel bar
guides 110 and 112 for engaging a mating hook 118 in the base 120
of an electrophotographic system for anchoring the cartridge 10, as
shown in FIG. 6.
The lower developer section 12 comprises means to develop the
recording element 30 at the developing station 36 during the
movement of the recording element 30 along its processing path.
Referring now particularly to FIGS. 6 and 7 of the drawing, the
developing station 12 is shown comprising a plurality of reservoir
compartments, such as a main compartment 122, a pressure
compartment 124, a bubble-filter compartment 126, and a
developer-return compartment 128. All of the compartments in the
developer section 12 communicate with each other through ducts,
such as ducts 130 and 132 between the main compartment 122 and the
pressure compartment 124, for example, and function as a combined
reservoir for the liquid developer 68. The pressure compartment 124
communicates with the filter compartment 126 through a narrow inlet
136 to remove any bubbles in the developer 68. The developer-return
compartment 128 also communicates with the main compartment 122, as
shown in FIGS. 6 and 7.
A pump 140 is provided within the developer section 12 to pump the
liquid developer 68 from the reservoir compartments to the
developing station 36. For example, a pump shaft 142 is journaled
in top and intermediate horizontal walls 144 and 146 of the
developer section 12 for rotation therein. A pump drive wheel 148
is fixed to the upper end of the pump shaft 142, and an impeller
150 is fixed to the lower end of the pump shaft 142 within the
pressure compartment 124. A circular plate 152, to prevent vortex
formations in the liquid developer 68, is disposed around, and
spaced from the pump shaft 142 within the main compartment 122. The
plate 152 is fixed to, and spaced from, the intermediate wall 146
by spacers 153. The horizontally disposed pump drive wheel 148
extends beyond the right wall 24 of the container 10 through a slot
154 therein.
The pump 140 is driven by means of a rubber friction wheel 156
coupled to a motor (not shown) external to the cartridge 10, when
the cartridge 10 is in the position for receiving light images from
the tube 40 and the drive means to drive the recording element 30,
as shown in FIG. 3. The rubber friction wheel 156 and driving means
therefor are not part of the cartridge 10 but cooperate with the
cartridge 10 when the latter is positioned in an
electrophotographic printing system adapted to receive it.
The developer 68 is introduced into the reservoir compartments of
the developer section 12 through an opening 58 in the top wall 144.
The opening 158 is fitted with a removable plug 160. A flattened
tubular member 162 (FIG. 6) communicates with, and extends from,
the filter compartment 126 and terminates in an elongated slit 164
which, in effect, is substantially adjacent the developing station
36. A metallic member 166 (FIG. 5) substantially covers the upper
portion of the tubular member 162 so that a bias voltage may be
applied thereto to cause it to function as a developing electrode,
in a manner well known in the electrostatic printing art. A
plurality of holes 168 are formed in the top wall 144 of the
developer section 12 on opposite sides of the metallic member 166
to provide a return path for the liquid developer 68 into the
developer return compartment 128. A stand pipe 170, extending to a
greater height than that of the tubular member 162, communicates
with the pressure chamber 124 to provide a constant head of
pressure for the liquid developer 68 emerging through the slit 164
at the developing station 36.
When the pump 140 is operated, as by coupling the pump drive wheel
148 to the rubber friction wheel 156, the impeller 150 forces the
liquid developer 68 through the narrow inlet 136 between the
pressure chamber and the filter chamber 126, thereby preventing
bubbles from entering the filter chamber 126. Also, the circular
plate 152 prevents a vortex formation in the liquid developer 68
and thereby prevents the formation of excess bubbling. The
pressurized liquid developer 68 is also pumped through the stand
pipe 170 so that it overflows and returns through communicating
ducts to the main and developer-return compartments 124 and 128.
The pressurized liquid developer 68 is also forced through the
tubular member 162. The pressure of the liquid developer 68
emerging through the elongated slit 164, adjacent the developing
station 36, is substantially constant and is determined primarily
by the pressure head provided by the difference in the height of
the stand pipe 170 with respect to the height of the tubular member
162. The arrows in FIGS. 6 and 7 indicate the flow path of the
liquid developer 68 under the influence of the pressure provided by
the pump 140.
Referring now particularly to FIG. 5, the top wall 144 of the
developer station 12 is shown as being formed with short raised
side portions 172 and 174 adjacent the sidewalls 24 and 26,
respectively, and long flattened portions 176 and 178 intermediate
the short raised side portions 172 and 174. This construction
provides the cartridge 10 with guide means for supporting the
recording element 30 adjacent its lateral parallel side edges and
preventing wet developed images on the recording element 30 from
touching the top wall 144, thereby preventing smearing of the
developed images. The liquid developer 68 may contain a highly
volatile carrier fluid and a chemical fixer to dry and fix the
developed image on the recording element 30 in a matter of seconds,
in a manner well known in the art. The cutter 70 is disposed
between the developer section 12 and the storage section 14 to cut
off a portion of the recording element 30 from the web, as desired.
To this end, the top wall 144 of the developer section 12 is formed
with a slot 180 for engaging a cutter bar 182 slidably therein. The
right and left sidewalls 24 and 26 of the cartridge 10 are also
formed with slots for receiving the cutter bar 182 slidably
therein, as shown in FIGS. 1 and 5.
The cutter bar 182 has a sharpened knife blade 184 extending
upwardly therefrom and disposed so as to cut through the web of the
recording element 30 at the cutting station 38 when the cutter bar
182 is moved slidably within the slot 180. The cutter bar 182 may
be actuated manually or it may be coupled to an arm 186 (FIG. 3)
for actuation by any suitable means in the electrophotographic
printing system in which the cartridge 10 is to be employed.
Before the replaceable cartridge 10 is inserted into an
electrophotographic printing system for cooperation therewith, it
is furnished with a fresh supply roll 28 of the recording element
30 threaded along the predetermined path including the charging
station 32, the image exposing station 34, the developing station
36, and the cutting station 38, as shown in FIG. 1. The wire 40 is
new and smooth to provide an even corona discharge when suitably
energized. The rollers 54, 56, and 58 are clean, the blade 184 of
the cutter 70 is sharp, and the liquid developer is fresh. The
supply of the liquid developer 68 is sufficient to develop all the
electrostatic images to be formed on the recording element 30.
Thus, when the supply of the recording element 30 is exhausted by
use, the liquid developer 68 is also substantially exhausted. The
operation of the electrophotographic printing system can continue,
however, by replacing the exhausted cartridge 10 with a new or
reserviced replaceable cartridge 10, thereby insuring substantially
continuous and efficient functioning of the electrophotographic
printing system.
* * * * *