Note: Descriptions are shown in the official language in which they were submitted.
Zall
A MULTI-MODE ELECTROSTATOGRAPHIC PRINTING MACHI~E
This invention relates generally to a multi-
mode electrostatographic printing machine. More parti-
cularly, this invention concerns an electrostatographic
printing machine arranged to operate in electrographic
and electrophotographic modes.
he process of electrostatographic printing
requires the formation and utilization of an electro-
static latent image for the purpose of recording and
reproducing patterns in viewable form. Electrostato-
graphic printing may include electrophotographic printing
and electrographic printing. In electrophotographic
printing,electromagnetic radiation is used to form an
electrostatic latent image on a photoconductive member.
An electrographic printing machine employs an insulating
medium to form, without the aid of an electromagnetic
radiation, an electrostatic latent image. Generally,
the process of electrophotgraphic printing includes
charging a photoconductive member to a substantially
uniform potential so as ~o sensitize the surface thereof.
The charged portion of the photoconductive surface 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 informa-
tional areas contained within the original document being
reproduced. After the electrostatic latent image is
recorded on the photoconductive member, the latent image
is developed by bringing particles of a developer mix
into contact therewith. The developer mix particles
are attracted to the latent image forming a particle
image on the photoconductive member. The particle image
is then transferred from the photoconductive member to
a copy sheet. Finally, the copy sheet is heated to per-
manently affix the particles thereto in an image con-
figuration. This general approach was disclosed by
~14(~Z~
Carlson in U. S. Patent No. 2,297,69i and has been
further amplified and described by many related patents
in the art.
In electrophotographic printing, the electro-
static latent image comprises electrostatic surface charges.
These surface charges may be transferred to, or reproduced
upon, other dielectric surfaces. The technique for accom-
plishing charge transfer is referred as a TESI process,
from transfer of electrostatic images~ Hence, electro-
static latent image may be transferred to another surface
prior to development. ~he material to which the electro-
static latent image is transferred must, of course, be
capable of retaining the image, i.e. it must be a good
insulator. Electrostatic latent images may be trans-
ferred to dielectric coated papers. The transferred
images can be developed by the same methods hereinbefore
described for developing the electrostatic latent image
recorded on the photoconductive member. However, since
the charge on the dielectric surface is not dissipated
by exposure to light, it is not necessary to shield the
image from light during development. When the electro-
static latent image has been transferred to a dielectric
sheet, the powder image image developed thereon may be
subsequently fused thereto forming a finished copy sheet.
In electrographic printing, an electrostatic
latent image is produced on a dielectric surface by the
use of electrodes. Electrostatic latent images produced
in this manner can be made visible by bringing developer
mix particles into contact therewith. The resultant
particle image may then be permenantly affixed to the
dielectric sheet or transferred therefrom to a copy sheet.
Various types of electrostatographic printing
machines have hereinbefore been employed to utilize the
foregoing processes. The following disclosures appear
to be relevant:
114()2~1
-- 3 --
U. S. Patent No. 2,825,814
Patentee: Walkup
Issued: March 4, 1958
U. S. Patent No. 3,686,676
Patentee: ~owell et al.
Issued: August 22, 1972
~. S. Patent No. 4,042,962
Patentee: Yamaji et al.
Issued: August 16, 1977
The relevant portions of these disclosures
may be briefly summarized as follows:
Walkup describes an electrophotographic printing
process in which an electrostatic latent image recorded
on a photoconductive member is transferred to a dielec-
tric member by applying a D.C. potential therebetween.
Howell et al. discloses an electrographic recording
apparatus wherein electrostatic charges are placed on
a recording medium by means of electrically pulsed electrodes
or styli.
Yamaji et al. discloses an electrophotographic
printing machine in which an electros~atic latent image
is recorded on a photoconductive member by charging and
then exposing the charged portion of the photoconducitve
member. Exposure is accomplished by illuminating an
original document and then transmitting the light rays
reflected therefrom through a lens which focuses the
light image onto the charged portion of the photocon-
ductive member recording the electrostatic latent image
thereon. Alternatively, a cathode ray tube may be
utilized to expose the charged portion of the photocon-
ductive member. In another mode of operation, a trans-
mission head records a telegraphic imaqe directly on
the photoconductive member.
114(32C~1
--4--
. ,
Various aspects of the invention are as ~ollows:
A multi-mode electrostatographic printing machine including:
a photoconductive member;
means for transporting a dielectric member along a path of travel;
a portion of said path being closely adjacent to said photoconductive member;
means for recording a first electrostatic latent image onto said
photoconductive member for transfer to said dielectric member;
a plurality of individually energizable styli positioned along said
path for forming a second electrostatic latent image onto said dielectric
member;
means for selectively applying electric po.e~ ials t~ individual ones
of said styli;
means for depositing particles on said dielectric member to
develop the electrostatic latent image;
a5 , means for affixing substantially permanently said particles to said
dielectric member; and
operator selectable means for energizing said recording means and
cajd styli cimultaneou51y or energizing either said recording means or said styli
independently.
A method of electrostatographic printing, including the steps
of:
recording a first electrostatic latent image on a photoconductive
member;
transferring the first electrostatic latent image to a dielectric
member;
forming a second electrostatic latent image on the dielectric
m ember by selectively applying electrical potentials to individually ener-
gizable styli positioned in close proximity to said dielectric member;
depositing particles on the dielectric member to develop the
electrostatic latent image thereon producing a powder image;
affixing substantially permanently the powder image to the
dielectric member; and
selecting said steps of recording and transferring to produce only
the first electrostatic latent image on the dielectric member, or said step of
forming to produce only the second electrostatic latent image on the dielec-
tric member, or said steps of recording, transferring and forming to produce
both the first electrostatic latent image and the second electrostatic latent
image on the dielectric member.
1~4(~2~31
-4a-
A multi-mode printing process for generating an image of
selected information creatable from different multiple information sources on
a dielectric n~ember comprising the steps of:
~) forming a first latent image on a photoconductor; said first
latent image generated from a first information source using a meQns to
impose a light pattern on said photoconductor;
b) transferring said first latent image from said photoconductor to
said dielectric member;
c) forming a second l~tent image on said dielectric member from
information generated by selectively energizing a number of individually
energizable styli positioned in close proximity to said dielectric member;
d) depositing particles on the dielectric member to develop the
electrostatic latent image thereon to produce a powder image and affixing
substantially permanently the powder image to the dielectric member; and
e) selecting said steps of forming said first and second images to
produce only the first l~tent image on the dielectric member, or only the
second latent image on the dielectric member, or both first and second latent
images on the dielectric member.
Other features of the present invention will
become apparent as the following description proceeds
and upon refexence to the figure, in which is shown a
schematic elevational view illustrating a multi-mode
electrostatographic printing machine incorporating the
25 features of the present invention therein.
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.
i~4()ZC~l
-4b-
~ or a general understanding of a multi-mode
electrostatographic printing machine, reference is had
to the drawing. In the drawing, like reference numerals
have been used throughout to designate identical elements.
The drawing schematically depicts the various components
of the multi-mode electrostatographic printing machine
having the various features of the present invention
therein. Inasmuch as the art of electrostatographic
printing is well known, the various processing stations
employed in the printing machine will be shown herein-
after schematically and their operation described with
1~.,.~
2~1
-- 5 --
reference thereto.
As shown in the drawing, the machine operator
may select any or all of three modes of operation. If
the machine operator depresses button 10 marked "CRT",
a cathode ray tube will be energized to illuminate the
charged portion of a photoconductive drum. This records
a latent image corresponding to the informational areas
contained within the cathode ray tube on the photoconduc-
tive drum. Alternatively, if the machine operator
depresses button 12, marked "COPIER", an original docu-
ment disposed upon a platen of the electrostatographic
printing machine will be reproduced. Finally, if the
machine operator depresses button 14, marked "STYLUS
ARRAY", information transmitted to a stylus array or
electrodes will be recorded on the copy sheet and re-
produced. The machine operator has the option of select-
ing any of the foregoing modes of operation or all of
them simultaneously. ~he multi-mode electrostatographic
printing machine hereinafter described prints electro-
photographically and electrographically. In order to
reproduce the information contained on the cathode ray
tube or on the opaque original document, the printing
machine operates in the electrophotographic printing
mode. However, when the information is being transmitted
to the stylus array, the printing machine operates in
electrographic mode. These modes of operation may be
combined to produce a composite single copy containing
information from the opaque original document, the
cathode ray tube, and the stylus array. Thus, the
printing machine may operate in any or all of the fore-
going modes.
Initially, drum 20 moves a portion of the
photoconductive surface through charging station A.
At charging station A, a corona generating device,
indicated generally by the reference numeral 24, charges
the photoconductive surface of drum 20 to a relatively
~1402~31
high, substantially uniform potential.
Thereafter, the charged portion of the photo-
conductive surface of drum 20 is advanced through expo-
sure station B. At exposure station B, original docu-
ment 16 is positioned face-down upon transparent platen
18. Transparent platen 18 moves in the direction of
arrow 26. The exposure system, includes stationary lamps
28 which illuminate the original document disposed on
the moving platen. As the platen moves, incremental
width light images are formed which are projected through
lens 30. Lens 30 focuses these light images onto the
photoconductive surface of drum 20. The angular velo-
city of drum 20 is synchronized to that of the linear
velocity of platen 18. In this manner, the charged photo-
conductive surface of drum 20 is discharged selectively
by the light image of the original document. This records
an electrostatic latent image on the photoconductive
surface of drum 20 which corresponds to the informational
areas contained within original document 16.
Next, drum 20 advances the electrostatic latent
image recorded on the photoconductive surface to transfer
station C. At transfer station C, the electrostatic
latent image recorded on the photoconductive surface
of drum 20 is transferred to a dielectric sheet. The
dielectric sheet is advanced to transfer station C
in synchronism with the advancement of the electrostatic
latent image thereto. A sheet feeding apparatus, indicated
generally by the reference numeral 32, advances the
dielectric sheet to transfer station C. Preferably,
sheet feeding apparatus 32 includes a feed roll 34 rotat-
ing in the direction of arrow 36. Feed roll 34 contacts
the uppermost sheet of a stack of dielectric sheets 38.
Each dielectric sheet may be of any composition suitable
~ for electrographic recording. Mylar, polystyrene and
polyethylene are examples of coatings which may be formed
on plain paper to produce a dielectric sheet capable
.~
tr~J~ rt~
ll~(SZ~'~
of retaining an electrostatic la~ent image thereon.
As feed roll 34 rotates in the direction of arrow 36,
the uppermost dielectric sheet is advanced from stack
38 to registration rollers 40. Registration rollers
S 40 rotate in the direction of arrows 42 to align and
forward the advancing dielectric sheet into chute 44.
Chute 44 directs the advancing dielectric sheet into
contact with the photoconductive surface of drum 20 in
a timed sequence so that the electrostatic latent image
recorded thereon is positioned opposed therefrom at
transfer station C.
At transfer station C, the electrostatic latent
image is transferred from drum 20 to the dielectric sheet.
Inasmuch as the charge on the dielectric sheet is not
dissipated by exposure to light, it is not necessary
to shield the image from light during the subsequent
processing steps. The dielectric sheet contacts a elec-
trode 46. Electrode 46 is preferably an elongated roller
rotating in the direction of arrow 48 so as to continue
to advance the dielectric sheet in the direction of
arrows 50. Roller 46 rotates in synchronism with drum
20. Voltage source 45 is connected between roller 46
and the conductive backing, i.e. aluminum of drum 20.
Voltage source 45 applies an electrical field between
the conductive backing of drum 20 and roller 46. The
dielectric sheet is in contact with roller 46. The
electrical field applied by voltage source 45 is of a
suitable magnitude and polarity to transfer the elec-
trostatic latent image from the photoconductive surface
of drum 20 to the dielectric sheet. Preferably, voltage
source 45 produces a potential difference between the
conductive backing of drum 20 and conductive roller 46
of about 1,000 volts. The dielectric sheet is spaced
from the photoconductive surface of drum 10. Preferably,
the spacing between the dielectric sheet and the photo-
conductive surface of drum 20 is in the order of several
;
~14(~20i
microns. Roller 46 is made preferably from a suitable
material such as aluminum or copper. Various techniques
have hereinbefore been described teaching the process of
transferring an electrostatic latent image from a
photoconductive surface to a dielectric sheet. Typical
techniques are described in U.S. Patent No. 2,833,648
issued to Walkup in 1958, U.S. Patent No. 2,937,943
issued to Walkup in 1960, U.S. Patent No. 2,975,052
issued to Fotland et al. in 1961, U.S. Patent No.
2,982,647 issued to Carlson in 1961, and U.S. Patent No.
3,055,006 issued to Dreyfoos et al. in 1962.
After the electrostatic latent image is
transferred to the dielectric sheet, a plurality of
rollers (not shown) advance the dielectric sheet along
chute 52 to moistening station D. At moistening station
D rollers 54 and 56, immersed in liquid 58, coat the
backside of the dielectric sheet with a liquid 56 so as
to improve the conductivity thereof. Preferably, liquid
56 is water which may have salt added thereto to improve
the characteristics thereof. Roller 58 presses the
dielectric sheet into contact with roller 54 so as to
meter a precise quantity of liquid onto the backside of
the dielectric sheet. Roller 60 controls the amount of
liquid absorbed by roller 54 for application to the
25 backside of the dielectric sheet. Preferably, rollers 54
and 60 may be foam or a suitable brush-like material.
Roller 58 rotates in the direction of arrow 62 so as to
continue to advance the dielectric sheet in the direction
of arrow 50. After the dielectric sheet has been
30 moistened, it advances to development station E.
At development station E, a magnetic brush
development system, indicated generally by the reference
numeral 64, advances magnetic particles into contact with
the electrostatic latent image formed on the dielectric
35 sheet. Magnetic brush system 64 includes a hopper 66 for
holding a supply of magnetic particles 68 therein. The
magnetic particles 68 are metered from hopper 66 onto
tubular member 70. Preferably, tubular member 70 is made
from a non-magnetic material such as aluminum. An
` -9- 114(~20~
elongated magnetic member 72 is disposed interiorly of
tubular member 70. In this manner, a magnetic field is
created which attracts magnetic particles 68 to tubular
member 70. Tubular member 70 rotates in the direction of
arrow 72 so as to advance the magnetic particles 68 into
contact with the electrostatic latent image formed on the
dielectric sheet. Conveyor 76 advances the dielectric
sheet through development station C. Preferably,
conveyor 76 includes a plurality of conductive fins for
supporting the sheet thereon. ~hese conductive fins
provide an electrode arrangement which the moistened
dielectric sheet rides on during development to assure
contact in a regular pattern. A voltage source (not
shown) applies an electrical potential of suitable
magnitude and polarity between conveyor 76 and tubular
member 70 to insure development of the electrostatic
latent image formed on the dielectric sheet. U.S. Patent
No. 3,714,665 issued to Mutschler et al. in 1973
describes a suitable structure for moistening a sheet
prior to the process of development.
After the electrostatic latent image formed on
the dielectric sheet has been developed with magnetic
particles, the dielectric sheet is advanced to fusing
station F. Fusing station F, indicated generally by the
reference numeral 78, includes a back-up roller 80 and a
heated fuser roller 82. The dielectric sheet with the
powder image thereon passes between back-up roller 80 and
fuser roller 82. Fuser roller 82 rotates in the
.~,`'
l~OZC~l
-- 10 --
direction of arrow 84 and back-up roller 80 rotates in
the direction of arrow 86. In this manner, both of the
foregoing rolls continue to advance the dielectric sheet
in the direction of arrow 50. The powder image contacts
fuser roller 82 and the heat and pressure applied thereto
permanently affixes it to the dielectric sheet. While
a heated pressure roller system has been heretofore
described, one skilled in the art will appreciate that
if suitable magnetic particles are employed, a cold roll
pressure system may be employed in lieu thereof. Thus,
rollers 80 and 82 would both be cold rather than having
roller 82 heated.
After fusing, conveyor 88 advances the finished
copy sheet, in the direction of arrow 50, to catch tray
90. When the sheet is in catch tray 90, it may be sub-
sequently removed therefrom by the machine operator.
The process heretofore described is only one
mode of operation for the electrostatographic printing
machine, i.e. wherein an opaque original document is
disposed on the transparent platen. In this mode of
operation, the machine operator has depressed button
12 marked "COPIER". Alternatively, the electrostato~
graphic printing machine may operate in any of the other
modes of operation. For example, if an opa~ue original
document is not positioned on the transparent platen,
but information is received on the cathode ray tube,
the machine operator would depress the button 10 marked
l'CRT". In this mode of operation, the photoconductive
surface of drum 20 is charged to a substantially uniform
level as heretofore described at charging station A by
corona generating device 24. After a portion of the
photoconductive surface has been charged, it moves to
exposure station B. At exposure station B, cathode
ray tube 92 projects a light image of an original docu-
ment through lens 94. Lens 94 focuses the light image
received from cathode ray 92 cnto the charged portion
~L14(~2C~
of photoconductive surface of drum 20. The light image
selectively discharges the charge thereon forming an
electrostatic latent image on the photoconductive sur-
face of drum 20. Thereinafter, the elec~rostatic latent
image recorded on the photoconductive surface of drum
10 proceeds through the same processing stations as the
electrostatic latent image recorded on photoconductive
surface 12 by the utilization of an opaque original docu-
ment disposed on a transparent platen, i.e. the process
heretofore described.
Sheet feeding apparatus 32 advances the di-
electric sheet to transfer station C in synchronism with
the electrostatic latent image recorded on the photo-
conductive surface of drum 20. At transfer station C,
voltage source 45 produces an electrical field between
roller 46 and the conductive backing of drum 20 so as
to transfer the electrostatic latent image on the photo-
conductive surface of drum 20 to the dielectric sheet.
The rollers in chute 52 continue to advance the dielec-
tric sheet in the direction of arrow 50 to moistening
station D.
At moistening station D, roller ~4 applies
a liquid coating, preferably water, to the backside of
the dielectric sheet improving the conductivity thereof.
The dielectric sheet is then advanced to development
station E where tubular member 70 advances magnetic
particles into contact with the electrostatic latent
image thereon. The magnetic particles are attracted
to the electrostatic latent image forming a powder
image.
Next, the dielectric sheet is advanced through
fusing station ~. At fusing station F, fusing apparatus
72 permanently affixes the powder image to the dielec-
tric sheet. Conveyor 88 then advances the sheet to catch
tray 90. It is thus apparent that the second mode of
operation i.e. wherein cathode ray tube 92 is energized,
~14()2~
- 12 -
is substantially the same as the mode utilizing an opaque
original document. The distinction resides in the manner
in which exposure station B operates. It should be noted
that if desired, both the cathode ray tube and the copy-
ing mode of operation may be operated simultaneously.
For example, a opaque original document may be reproduced
and the cathode ray tube may form a screen pattern in
superimposed registration thereon. Alternatively, the
opaque original document may be a standard form with
the cathode ray tube providing specific information
therefor. Thus, the electrostatic latent image recorded
on the photoconductive surface of drum 20 may be a com-
posite latent image containing information from the
cathode ray tube and the opaque original document. It
is thus evident that the electrostatographic printing
machine may operate in either the copying mode wherein
only an original document is reproduced, or in the CRT
mode wherein information from a cathode ray tube is
reproduced. Not only may the electrostatographic print-
ing machine operate in either of those modes but it may
also operate in both of those modes simultaneously to
record information on a common electrostatic latent image
from both of the foregoing information sources.
Considering now the third mode of operation,
where only "STYLUS ARRAY" button 14 is actuated. In
this mode of operation, the dielectric sheet is advanced
by sheet feeding apparatus 32 through chute 44 and between
roller 46 and drum 20 to chute 52. The surface of chute
52 is a segmented conductive backing electrode for support-
ing the backside of the dielectric sheet. A stylus array
96 is positioned closely adjacent to the surface of the
segmented backing electrode 98 as it moves thereacross.
Stylus array 96 is a sheet width array which typically
contains between l,000 and 4,000 stylii or electrode
elements. On receipt of a signal, the stylus array is
excited to a suitable potential and magnitude. Selective
1~4(~2~:~
excitation of stylii, individually forms an electrostatic
latent image on the dielectric sheet. In the alterna-
tive, an array of ion guns may be utilized in lieu of
the stylii array. Other suitable electrode arrangement,
as disclosed in the prior art, may also be utilized.
Backing plate 98 is electrically grounded.
After the electrostatic latent image has
been formed on the dielectric plate by the selective
energization of the stylus array, the dielectric sheet
passes through moistening station D. At moistening
station D, roller 54 applies a metered quantity of
liquid to the backside of the dielectric sheet improv-
ing the conductivity thereof. Thereinafter, the dielec-
tric sheet passes through development station E.
At development station E, tubular member 72
deposits magnetic particles on the electrostatic latent
image forming a powder image thereon.
~hereinafter, the dielectric sheet with the
particle image thereon passes through fusing station
2~ F. At fusing station F, heated fuser roller 82 and back-
up roller 80 apply heat and pressure to the powder
image permanently affixing it to the dielectric sheet.
Thereinafter, conveyor 80 advances the dielectric sheet
with the powder image permanently affixed thereto, in
the direction of arrow 50, to catch tray 90 for subse
quent removal from the printing machine by the machine
operator.
It is thus apparent that in this latter mode
of operation, the printing machine operates in an elec-
trographic mode of operation. Thus the electrostato-
graphic printing machine heretofore described may operate
in either an electrographic or electrophotographic mode.
Not only may it operate in either of these modes indivi-
dually but in combination with one another. For example,
an electrostatic latent image may be formed on the
photoconductive surface by the utilization of a cathode
114(~Z~l
- 14 -
ray tube and/or the information contained within an opaque
original document disposed upon the moving transparent
platen. The resultant composite electrostatic latent
image may then be transferred to the dielectric sheet.
Thereinafter, information may be recorded on the dielec-
tric sheet by the stylus array. Thus, an electrostatic
latent image may be formed on the dielectric sheet which
contains information from an opaque original document,
a cathode ray tube, and a stylus array. The resultant
electrostatic latent image may contain information from
all or any of the foregoing.
In recapitulation, it is evident that the multi-
mode electrostatographic printing machine of the present
invention forms an electrostatic latent image on a
dielectric sheet. The electrostatic latent image may
contain information from an opaque original document,
a cathode ray tube, and a stylus array. The resultant
electrostatic latent image may be formed from the informa-
tion contained in any one or all of the foregoing. This
latent image is then developed and permanently affixed
to the dielectric sheet forming a copy of the information
contained within the cathode ray tube, opaque original
document, or the stylus array.
It is apparent that the multi-mode electrosta-
tographic printing machine operates in the electrophoto-
graphic mode of operation and the electrographic mode
of operation. The electrophotographic mode of operation
utilizes either a cathode ray tube or an opaque original
document, or both of the foregoing. The electrographic
mode of operation employs a stylus array or any equivalent
electrode known in the art. The operator may select
any single mode of operation or any combination of modes
of operation merely by depressing the appropriate button
or buttons. For example, depression of the cathode ray
tube button actuates only the cathode ray tube. Similarly,
depression of the copier button actuates only the opaque
`` 11~02(~
- 15 -
original document mode of operation. Finally, actuation
of the stylus array button merely actuates the stylus
array. In order to actuate a combination of the fore-
going, any two or all three of the foregoing buttons
must be depressed.
While a cathode ray tube has been hereinbefore
described, one skilled in the art will appreciate that
any other electronic imaging technique may be employed,
such as using a laser beam or a plurality of fiber optics
to form an electrostatic latent image on the photocon-
ductive member.
It is, therefore, evident that there has been
provided, in accordance with the present invention, a
multi-mode electrostatographic printing machine that
fully satisfies the aims and advantages hereinbefore
set forth. While this invention has been described in
conjunction with a specific embodiment thereof, it will
be evident that many alternatives, modifications, and
variations will be apparent to those skilled in the art.
Accordingly, it is intended to embrace all such alterna-
tives, modifications, and variations as fall within the
spirit and broad scope of the appended claims.
