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Патент USA US3023741

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March 6, 1962
F. A. scHWERTZ
3,023,731
ELECTROSTATIC ALPHANUMERICAL PRINTER WITH
IMAGE TRANSFER MECHANISM
Filed June 6. 1957
2 Sheets-Sheet 1
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March 6, 1962
3,023,731
F‘ A. scHwl-:RTZ
ELECTROSTATIC ALPHANUMERICAL PRINTER WITH
IMAGE TRANSFER MECHANISM
Filed June 6. 1957
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United States Patent() Mice
1
i
3,023,731
Y Patented Mar. 6, 1962
2
proximity to an yinsulating surface, Vsuch as a web of di
electric material. The web is electrostically pre'charged
3,023,731
ELECTROSTATIC ALPHANUMERICAL PRINTER
WITH IMAGE TRANSFER MECHANISM
Frederick A. Schwertz, Pittsford, N.Y., ‘assigner to The
Haloid Company, Rochester, N.Y., a corporation of
New York
by ’an intense electric field to 'a point somewhat below
critical stress value. Alternatively a static bias voltage
may be 'applied to bring 'the applied fìeld’to the point of
incipient breakdown.
n
Transfer of the configuration of the symbol or charac
ter from the Vshaped electrode to the insulating web is
effected by the use of a relatively low potential trigger
The present invention relates generally to high-speed 10 ing ‘pulse which raises the electric field above the critical
stress ’value toiproduce a field discharge in the Vspace be
recording of computational data'and more particularly to
tween the insulating web and the electrode. The dis
apparatus adapted jto record alphanumerical information
charge action gives rise to the formation of an electro
electrostatically as "latent images on a continuous insulat
static pattern of the symbol on the insulating surface.
ing medium, ‘which images are thereafter developed and
Filed June 6, 1957,’Ser. No.'664,138
17 Claims. (Cl. V11S-'625)
transferred to `an ordinary printing paper.
15 Electronic switching circuits'are associated with the elec
The written or pr'rnted 'values yielded by ‘the output
system of'an »electronic computer may assume any one of
trostatic apparatus to supply trigger pulses thereto in
accordance with information ‘received electrically from a
digital vcomputer or other signal source. This process is
now known as Tesiprinting (Transfer Electro Static
several forms depending ‘on 'the ‘nature of the data and
its eventual use. With vthe recent development of high
.
speed computer machines and other mechanical and elec 20 Image).
In the copending applications, alphanumerical charac
tronic devices which produce data at high rates of speed,
ters are formed with the aid of raised character-metal
there has arisen a concomitant need for high-speed record
elements disposed about the circumference of a cylin
ing devices, ’for otherwise the printer or other recording
drical drum, one column of characters being provided
mechanism may act to retard the operation of'the entire
machine. Where vthe production rate of output data 25 for each column of the printed page. The characters are
caused to pass in the vicinity of a paper web by rotating
exceeds the 'capacity of the output printer, the usual
the character drum at a constant angular velocity. Dis
practice is to ’store the output information as rapidly as
posed above the paper is an array of electrodes, one for
it is produced and to feed it from storage to the printer
each column to’beprinted. When the selected character
as rapidly as the printer will accept 'thein'formation
In the copending applications entitled “Electrostatic 30 passesv beneath a chosen electrode, a high-voltage pulse is
applied to effect a field discharge between the selected
Recording of -Information,” Ser. No. 623,327, filed No
character and the web at a position corresponding to that
vember 20, 1956 (now abandoned), and “High-Speed
Electrostatic Alphanumerical Printer,” Ser. No. 664,137,
of the chosen electrode.
y
The field discharge causes the formations of latent elec
tiled June 6, 1957 (now issued as Patent No. 2,919,967),
there is described a novel electrostatic image-forming 35 trostatic images on the paper web passing over the char
acter drum. When the web is withdrawn from the elec
technique for recording alphanumerical information,
trostatic apparatus, it passes through a development
which technique overcomes many of the drawbacks char
mechanism wherein the invisible electrostatic images are
acteristic of known mechanical and optical printers.
rendered visible by depositing thereon `a finely divided
The electrostatic image-forming process as disclosed
powder which adheres to the charged image areas. To
in said copending applications makes possible the trans
fer of electrostatic images to a recording medium at eX
romote development, the particles are preferably charged
tremely high speeds, these images being subsequently
by triboelectric or other means. Thereafter the powder
images are fused onto the paper to form a permanent
print of the information recorded.
rendered visual by methods conventional in the Xero
graphic art. Digital computer switching circuits co-act
Thus in the electrostatic printing devices of the type
ing with the electrostatic image-forming apparatus per 45
described in the above-identified copending applications,
mit the logical spacial ordering of electrostatic images
the paper web must possess characteristics rendering it
which owe >their origin to information pulses received
suitable for supporting an electrostatic image as well as
serially in time.
In the art of Xerography in its electrophotographic 50 providing a printing surface for a powder image. This
aspects, an electrostatic charge applied to the surface of
a photoconductive insulating layer is selectively dissipated
by exposure to a pattern of light and shadow to be
recorded, thereby forming on the surface of the insulat
ing layer an electrostatic latent image corresponding to 55
said pattern. An image formed in this fashion may be
requires the use of a carefully dried paper or a paper
specially treated to afford a recording surface of high
resistivity to sustain an electrostatic charge. This require
ment precludes the use of ordinary paper and adds ma
terially to the cost of the operation. _
In view of the foregoing it is the principal object of
the present invention to provide a non-optical electro
developed by the deposition of finely divided material in
conformity with the charge pattern and thereafter fixed
static printer for recording alphanumerical information
tus involved in developing and fixing pictures may be
provide a high-speed electrostatic printer wherein electro
wherein the information may be printed on inexpensive
by fusing the powder on the surface of a print to which
_ Y
the powder pattern has been transferred. A detailed de 60 paper of ordinary quality.
More particularly, it is an object of this invention to
scription of the Xerographic technique and of the appara
found in the U.S. Patent to Carlson No. 2,297,691.
static images may be formed on a continuous flexible
being made permanent by fusing or drying. The electro
static images are produced by character faces or symbol
stituted by a bank of character Vrings insulated from each
other, whereby the rings may be separately pulsed. In
shaped electrode elements which are brought in close
accordance with an important feature of the invention,
web of insulating material, which images are then trans
In the apparatus disclosed in the copending applica
tions as distinguished from Xerography in its electrophoto 65 ferred to ordinary paper. A significant feature of the
invention is the fact that the continuous web may be re
graphic aspects, physical symbols or characters rather
used indefinitely, the image thereon being erased after
than light patterns are recorded as electrostatic images.
transfer is effected.
The images are then developed by depositing a finely
Also, an object of the invention is to provide a charac
divided powder or an ink mist, the resulting visible images
ter drum for an electrostatic printer, which drum is con
3
3,023,731
each character ring on the drum is associated with a
commutator ring cooperaitng with an electrode spaced
therefrom. A field discharge is produced between the
character ring and an associated endless metal belt hav
ing an insulating layer thereon, the lines of stress extend
ing through a gap between the electrode and the com
mutator ring.
Also an object of the invention is to provide an electro
static printer wherein alphanumerical images are simu
lated by selective activation of an array of electrode pins
carried on stationary matrix type recording heads.
Briefly stated, in an electrostatic apparatus for record
ing and printing alphanumerical information in accord
4
locity by a suitable motor. Arranged across the drum
is a bank of identical character rings 14, each containing
a circumferential assembly of raised-character metallic
elements 15. One ring of characters is provided for each
column to be printed. The characters in each ring
thereof are composed of alphabetical letters, numbers
and other symbols, each representative of a different value
of the applied information. The drum may be exactly
normal to the continuous web, or slightly askew. This
l() factor will be discussed later in the specification. "Ihe
character rings are slightly spaced from the web to define
an air gap in which a field discharge may occur to effect
an image transfer.
ance with the invention, the information received from a
Supported below the web in alignment with the drum
computer or other data source is recorded electrostatically 15 is an array of stationary electrodes 16, one for each ring
on an endless medium having an insulating surface of
in the character drum, the electrodes occupying corre
high resistivity for sustaining electrostatic charges. This
sponding positions. By means of an electrode pulsing
endless medium may be constituted by a continuous belt
supply repersented by block 17, the electrodes are se
of insulating material or a continuous metal belt having
quentially activated such that only one electrode is active
an insulating layer thereon. Alternatively, the endless 20 at a time to permit electrostatic recording at a corre
medium may take the form of a rotary metallic cylinder
sponding position on the web. In operation, when a
having an insulating layer coated thereon.
character on the ring representative of the input infor
A character-forming station is supported in spaced re
lation to the insulating surface of the recording medium
to define an air gap therebetween.
The character sta
tion includes character-forming elements adapted to pro
duce latent electrostatic images on said medium when
voltages are applied thereto effecting a field discharge in
mation is angularly aligned with the activated electrode
a field discharge is produced to form a charge pattern
25 on the web having the shape of the selected character.
The manner by which the characters are selected and
the electrodes are activated is treated in greater detail
in said copending application. A disc 18 is attached to
one end of the drum, the disc containing magnetic in
drum containing rings of raised-character elements which 30 dexing marks 19 in a circumferential arrangement at
may be selectively aligned with the medium. Alterna
positions corresponding to the character positions on
the air gap. The station may be constituted by a rotary
tively, the character-forming elements may be constituted
the rings. As disclosed in said applications, these marks
by an array of pins which may be selectively actuated by
are sensed by a magnetic head (not shown) to produce
pulses to build up the character by a pattern of dots.
voltage impulses at time positions reflecting the angular
The medium is moved relative to the character station 35 positions of the characters on the rings. A magnetic
to produce successive lines of characters thereon. A
mark on the other end of the drum cooperating with an
charging station is disposed in advance of the character
other pick-up head serves to indicate a full revolution
station to pre~stress the medium to a uniform potential
of the drum.
and thereby erase previously made electrostatic latent
In the electronic control system for the character
images. The medium after recording passes through a 40 drum described in the copending application “Electro
developer section to form powder images. 'Ihe powder
static Recording of Information,” the logical circuitry
images are transferred by electrostatic attraction to a
requires a synchronous serial input at the specified print
paper strip and the powder images thereon are fused to
ing rate, whereas in the system described in the copend
provide a permanent print.
ing application “High Speed Electrostatic Alphanumerical
For a better understanding of the invention, as well
Printer,” information may be printed as received on a
as further objects and features thereof, reference is made 45 random basis, the operation being asynchronous. Either
to the following detailed description to be read in con
circuit may be used in conjunction with the character
nection with the accompanying drawing, wherein like
components in the several views are identified by like
reference numerals.
drum in the present invention. By increasing the corn
plexity of the logical circuitry and providing a buffer
storage system, the printer can be made to record a line
50 for every revolution of the character drum rather than
FIG. 1 shows schematically a perspective view of one
one digit or letter per revolution.
«In the drawing:
preferred embodiment of an alphanumerical printer in
accordance with the invention;
The direction of motion is counter-clockwise whereby
the continuous web is iirst subjected to a pre-stressing
FIG. 2 shows schematically a perspective view of a
potential before it arrives at the character drum for
second preferred embodiment of an electrostatic printer 55 recording. This is accomplished by means of a corona
in accordance with the invention;
charging station 20 positioned in advance of the character
FIG. 3 is a separate elevational view of the character
drum which pre-stresses the web to a uniform potential
drum shown in FIG. 2;
below the critical stress value, such that a relatively
FIG. 4 is a schematic diagram of a third embodiment
small pulse at the recording station 13 is sufficient to
of the invention;
lFlG. 5 is a detail of FIG. v4;
FIG. 6 is a further embodiment of the invention, shown
schematically; and
60 produce a field discharge effecting image transfer.
The
corona charging station 2i) also acts to equalize the
charged on the web, thereby erasing all previously re
corded charges in preparation for the next recording
FIG. 7 is a detail of FIG. 6.
cycle.
`Referring now to FIG. l, the electrostatic printer com 65
The web leaving the character drum and carrying the
prises an endless web 10 supported between a pair of
electrostatic charge pattern enters a development section
spaced rollers 11 and 12. Web 10 is composed of a
2.1 of standard design in which powder is Howed over
flexible material of high resistivity such as Mylar or
the latent electrostatic images, the powder adhering only
Teflon, the material being capable of holding an electro
to the charged areas. The powder is caused to fall on
static image for a period which permits subsequent utili 70 the image layer as it turns about roller 12 and to move
Zation thereof by transfer to another surface.
downwardly thereover by gravity in a continuous stream,
Supported above the upper portion of the web at a
the powder being evenly distributed over the image. The
position substantially transverse thereto is a character
operation and structure of the developer section is more
drum, generally designated by numeral 13. Drum 1?» is
fully disclosed in the patent to Schaffert No. 2,576,047,
rotatably mounted and driven at a constant angular ve 75 issued November 20, 1951.
3,023,731
tú
Ö
6
in nature to the rings on the drum shown in FIG. 1. The
The resultant powder images formed on the web are
rings are, however, electrically insulated from each other
transferred to a paper strip 22 which is fed from a suit
by insulating discs 33. Adjacent each ring and electri
able supply roll 23, the strip travelling lover a transfer
cally connected thereto is a commutator ring 34. Fixedly
roller 24 and being rewound on a take-up roller 25. The
characters must be put on the web “wrong reading” and Ul mounted above the drum is an array of electrodes ’35,
each electrode being disposed in spaced relation to a re
from right to left so that they are “right reading” and
spective commutator ring.
left to right on the final paper support.
The arrangement is such that each character ring may
The transfer roller 24 is supported transversely with
be pulsed separately, as distinguished from. the previously
respect tothe lower portion of the web 10 intermediate
the web rollers 11 and 12 and acts to carry the paper 10 disclosed arrangement in which all of the character rings
>strip into momentary contact with the web; the web and
were electrically interconnected. The character rings on
strip moving in like directions at the same speed. The
the drum, as best seen in FIG. 3, are in spaced relation
supply roller 23 and take-up roller 25 are mounted be
to the web layer Sdu, to define a ñrst air gap 36, andthe
low the web rollers l1 and 12, all of the rollers being
electrodes 35 occupy spaced positions relative to the corn
supported in suitable bearings on a frame. Thus the
mutator rings 34 to define a second air gap 37, The
only point of contact between the paper strip 2-2- and the
character drum is supported on bearings insulated from
web 1i) is at the position of the transfer roller.
the ground.
The transfer roller 24, which may be made of con
Thus when a pulse is applied to an electrode 35 rela
ductive rubber material, is connected to a voltage source
26 which functions to impress a charge across the region
of the paper strip 22, engaging web 10. The magnitude
of the charge applied to the paper strip and the polarity
tive to ground, a corona discharge will proceed across
thereof is such as to overcome the adhesion of the
powder particles to the image area on the web and to
trostatic image transfer region. The electronic control
both air gaps, the gap between the pulsing electrodes and
the drum serving as a commutator connection, while the
gap between the drum and the web functions as an elec
circuit responsive to the input information to be recorded
acts to apply the pulses to theelectrodes when the selected
characters are angularly aligned with the endless dielectric
image -to the paper strip. The charge applied to the
coated metal belt.
paper strip by the transfer roller is of opposite polarity
The operation of the printer illustrated in FIGS. 2` and
to the charge on the developer powder, the powder there
3 is otherwise identical with that shown in FIG. l. The
fore being attracted to and retained by the paper strip.
30 web is ñrst pre-stressed at the corona station and after
The powder image transferred to the paper strip is
the electrostatic image is recorded it is developed to form
fused thereon by heating elements 27 of any suitable
a powder image, which image is transferred to a paper
construction disposed in operative relation to the strip
strip and fixed thereon. As indicated earlier, it is pos
between the transfer roller 24 and the take-up roller 25.
sible to print a full line in a single rotation of the char
To remove residual powder from the web 10 after the
acter drum providing a buffer storage system is employed
establish a greater tendency of the particles to adhere
to the paper, thereby effecting a transfer o-f the powder
transfer operation is completed and before it again enters
the charging station for the next recording, a rotary
brush 2S is provided which engages the web against its
roller 11. The brush acts to remove any powder adher
to handle a line-at-a-time of information.
If the web is permitted to move continuously during
the recording interval it will move a short distance for
ward. Since the character images will be formed ran
ing to the insulating web which has not been previously 40 domly along the line during this period, the characters will
transferred to the paper strip, thus preparing the web for
go down in positions slightly staggered with respect to
a fresh supply of powder. The cleaning means may
For example, if the character drum is ro
Y one another.
consist of any sui-table wiping or suction device and is
tating at a frequency of 200‘ revolutions per second and
preferably of the type disclosed in the patent to Turner
the web is travelling, say, at a rate of 3 inches per sec~
et al. No. 2,751,616, issued Iune 26, 1956. After the web 45
ond, the paper will advance 0.0Il5 inch. This then is the
has been cleaned of residual toner the charging station
maximum
'displacement distance between adjacent char~
2t) acts uniformly to charge the web 191 to a pre-selected
acters. For characters 0.1 inch high, that is roughly of
potential by means of corona wires.
typewriter size, such a displacement would probably be
In the event'the recording operation is carried out
noticeable and therefore objectionable. This can be ob
while the web is moving continuously, it is then necessary
viated by moving the web intermittently in the manner
slightly to skew the character drum 13 relative to the
indicated previously, such that the web is stationary when
web to compensate for the web motion and thereby insure
recording takes place.
that the course‘of the printed line runs perpendicularly
It is also possible, as shown in FIG. 4, to use a matrix
to the edges of the web. Alternatively, the rings on the
or a point array type of character presentation which may
drum may be staggered relative to each other for the
be selectively pulsed in such a'way as to simulate any
same purpose, in which case the ydrum need not be skewed.
alphanumerical character, thus eliminating the need for
But if the web is held stationary during the recording of
a moving character drum.
a line, then »the »character drum may be supported di
In FIG. 4, in place of the endless web, a rotary metal
rectly across the web without skewing. In this case, the
body of the web and the transfer strip are advanced in a 60 cylinder 38 is employed which is coated with a layer 39
of material having a high resistivity for holding an elec
stepwise manner a line at a time by a suitable indexing
trostatic image. The cylinder moves in a counterclock
mechanism actuated upon completion of each line. A
wise direction and is'pre-stressed «at the »corona station
common drive maybe provided for said web and said
’20. A stationary character printing station 40 is provided
strip to maintain synchronous movement thereof.
Referring now to'FIGS. 2 and 3, there is illustrated an 65 constituted by a bank of recording heads 41 having elec
trode points or pins 42 which can beselectively pulsed to
other embodiment of the invention which is identical to
provide a matrix type of presentation simulating an alpha
that ~shovvn in FIG. l, save for the structure of the re
numerical character. One head is provided at each col
cording web, lthe `character drum and the related elec
umn position. As shown in the drawing, the characters
trodes. The web supported between rollers ‘l1 and 12 is
constituted -by an endless metal belt 30 having a thin 70 are each formed by a pattern of dots.
Each recording head 41 consists of a set of five flat
insulating layer 36a of high surface resistivity coated
faced pins 42 in a row maintained at a fixed distance from
thereon. The metal belt is grounded through the sup
porting rollers l11 and 12 therefor. Rotatably supported
above the upper section of web 30 is a character drum
the surface of the cylinder layer 39‘, the pins of the several
heads running across the cylinder. The individual char
31 havinga series of character rings 32 thereon similar 75 acters are built up by seven successive choices of the five
aoaavsr
7
pins as the cylinder moves forward. An electronic puls
ing circuit is provided for each pin. Thus as the cylinder
rotates, the pins in the heads are selectively activated by
input information in seven successive steps to construct
latent images of the appropriate characters on the cylin
der surface.
A magnetic matrix and decoding unit may be used to
buffer the pulsing circuits to the pins and the information
source. A description of a unit adaptable for this pur
pose as well as an electronic pulsing circuit for the pins
0
previous charges, developer means operatively disposed
with respect to said medium beyond said station to form
powder images of said latent images, and means oper
atively coupled to said medium to transfer said powder
images onto a paper strip by electrostatic attraction.
3. An electrostatic apparatus for recording and print
ing alphanumerical information at high speed, said ap
paratus comprising an endless recording medium having
an insulating surface of high resistivity for sustaining
may be found in the article “Burroughs Electrographic
electrostatic charges, a character-forming station sup
ported in spaced relation to said insulating surface to
Printing Technique” by Herman Epstein, March 1955
Proceedings of the Western Joint Computer Conference
forming conductive elements adapted to produce latent
(AIRE-IRE).
electrostatic images on said medium when voltages are
The latent images impressed electrostatically on the
cylinder are developed at the development section 21, and
the resultant powder image is transferred to a paper strip
field across said air gap above the critical stress value
22 in the manner described hereinabove. After the trans
means to move said medium relative to said character
fer operation, the cylinder is cleaned of residual toner by
the rotary brush 2S, and the surface is pre-stressed in
preparation for the next recording.
forming station to form successive lines, charging means
operatively disposed with respect to said medium in ad
define an air gap therebetween and including character
applied thereto having an amplitude raising the electric
and thereby effecting a field discharge in said air gap,
vance of said station to pre-stress same to a uniform
potential and thereby erase previous charges, developer
In FIGS. 4 and 5, the characters are built up of a point
means operatively disposed with respect to said medium
array in seven successive. steps as the cylinder advances
beyond said station to form powder images of said latent
relative to the single row of pins. Alternatively, each re
cording head 43, as shown in FIGS. 6 and 7, may con 25 images, and means operatively coupled to said medium
to transfer said powder images onto a paper strip by
sist of seven rows of pins 44, five in each row. This
electrostatic attraction, said last named means including
makes possible the formation of the character matrix in
a paper strip movable in synchronism with said medium,
one step but involves a more complex pulsing and de
a transfer roller for effecting engagement between said
coding circuit. It is necessary to use seven coordinated
decoding units whereby all seven rows of pins may be 30 strip and said medium, and means to apply a potential
to said transfer roller to attract said powder image to
selectively pulsed at the same time to form the desired
alphanumerical character.
While there have been shown what are at present con
said strip.
4. A high-speed apparatus for recording and printing
alphanumerical information, said apparatus comprising
sidered to be preferred embodiments of the invention, it
will be obvious that many changes and modifications 35 a continuous belt of insulating material, a rotary char
may be made therein without departing from the essential
aspects of the invention. It is intended, therefore, in the
acter drum having a bank of like character rings thereon,
each ring containing a series of character-shaped raised
conductive elements in a circumferential arrangement,
appended claims to cover all such changes as fall within
the respective characters in the series being representa
the true spirit of the invention.
40 tive of different values of incoming information, said
What is claimed is:
drum being disposed across said belt and in spaced re
1. An electrostatic apparatus for recording and print
ing alphanumerical information at high speed, said ap
paratus comprising a movable endless recording medium
having an insulating surface of high resistivity for sus
taining electrostatic charges, a character-forming station
supported in spaced relation to said insulating surface
to define an air- gap therebetween and including char
lation thereabove to define an air gap, an array of fixed
electrodes disposed below said belt at positions corre
sponding to those of said rings, means responsive to the
value of incoming information to apply a voltage pulse
between one of said electrodes and said rings when the
characters thereon representative of said value are in
acter-forming conductive elements adapted to produce
angular alignment with said belt, said pulse having an
latent electrostatic images on said medium when volt
ages are applied thereto having an amplitude raising the
electric field across said air gap above the critical stress
value and thereby effecting a field discharge in said air
gap, means operatively disposed with respect to said
amplitude raising the electric ñeld across said air gap
above the critical stress value to effect a field discharge
in said gap and thereby forming an electrostatic latent
medium beyond said station to form powder images of
said latent images, and means operatively coupled to
said medium to transfer said powder images onto a
printing surface by electrostatic attraction.
image of the selected character on said belt at a position
in accordance with said electrode, means to move said
belt relative to said drum to form successive lines of
characters thereon, charging means operatively disposed
relative to said belt in advance of said drum to pre
stress said belt to a uniform potential, a developer sec
tion operatively disposed relative to said belt at a po
2. An electrostatic apparatus for recording and print
sition beyond said station to form powder images of
ing alphanumerical information at high speed, said ap
paratus comprising an endless recording medium having 60 said latent images, and means operatively coupled to
said belt to transfer said powder images onto a paper
an insulating surface of high resistivity for sustaining
strip by electrostatic attraction.
electrostatic charges, a character-forming station sup
5. A high-speed apparatus for recording and printing
ported in spaced relation to said insulating surface to
define an air gap therebetween and including character
alphanumerical information, said apparatus comprising
a continuous belt of insulating material of high resistivity
for
sustaining electrostatic charges, a rotary character
electrostatic images on said medium when voltages are
drum supported substantially transversely relative to the
applied thereto having an amplitude raising the electric
outer surface of said belt and having a bank of like
ñeld across said air gap above the critical stress value
character rings thereon, each ring containing a series
and thereby effecting a field discharge in said air gap, 70 of character-shaped raised conductive elements in a cir
means to move said medium relative to said character
cumferential arrangement, the respective characters in
forming station to form successive lines of latent images
the series being representative of different values of in
thereon, charging means operatively disposed with re
coming information, said drum being disposed in spaced
spect to said medium in advance of said station to pre
relation to said belt to define an air gap, an array of
stress same to a uniform potential and thereby erase 75 fixed electrodes disposed transversely relative to the un
forming conductive elements adapted to produce latent
3,023,731
der surface of said belt at positions corresponding to
those of said rings, means responsive to the value of
incoming information to apply a voltage pulse between
one of said electrodes and >said rings when the charac
ters thereon representative of said value are in angular
responsive to the value of incoming information to ap
ply a voltage pulse to a selected electrode relative to
said metal belt when the characters on said drum rep
resentative of said value are in angular alignment with
said belt, said pulse having a magnitude raising the elec
alignment with said belt, said pulse having an amplitude
tric ñeld above the critical stress value and effecting a
raising the electric field across said air gap above ythe
critical stress value to effect a field discharge in said gap
and thereby `forming an electrostatic latent image of
ñeld discharge between said characters and said insulat
ing layer to form an electrostatic latent image thereon.
9. A high-speed apparatus »for recording and printing
acters thereon, charging means operatively disposed rela
charges, a rotary character drum supported substantially
transversely relative to said belt in spaced relation there
the selected characters on said belt at a position in 10 alphanumerical information, said apparatus comprising
a continuous metal belt having an outer layer of in~
accordance with said electrode, means to move said belt
sulating material thereon for sustaining electrostatic
relative to said drum to form successive lines of char
tive to said belt in advance of said drum to pre-stress
said belt to a uniform potential, a developer section
operatively disposed relative to said belt at a position
to to deñne an electrostatic air gap, said drum having a
bank of like character rings thereon insulated from each
other and a bank of commutator rings each adjacent to
and in electrical contact with a respective character ring,
each ring containing a series of character~shaped con
beyond said station to form powder images of said latent
images, and means operatively coupled to said belt to
transfer said powder images onto a paper strip by elec
ductive elements in a circumferential arrangement, the
trostatic attraction.
20
respective characters in the series being representative
6. A high-speed apparatus for recording and printing
of different values of incoming information, an array
of ñxed electrodes aligned with said commutator rings
and spaced therefrom to form a commutating air gap,
sistivity for sustaining electrostatic charges, a rotary char
acter drum supported substantially transversely relative 25 means responsive to the value of incoming information
to apply a voltage pulse to a selected electrode relative
to the outer surface of said belt and having a bank of
alphanumerical information, said apparatus comprising
a continuous belt of insulating material of high re
like character rings thereon, each ring containing a series
to said metal belt when the characters on said drum
representative of said value are in angular alignment
with said belt, said pulse having a magnitude raising the
cumferential arrangement, the respective characters in
the series being representative of different values of 30 electric ñeld above the critical stress value and effecting
a ñeld discharge between said characters and said in
incoming information, said drum being disposed in spaced
sulating layer to form an electrostatic latent image there
relation to said belt to deline an air gap, an array of
of character-shaped raised conductive elements in a cir
on, and means to form a powder image of said latent
fixed electrodes disposed transversely relative to the un
image and to transfer same to a paper strip.
der surface of said belt at positions corresponding to
l0. High-speed apparatus for recording and printing
those of said rings, means responsive to the value of 35
incoming information to apply a voltage pulse between
alphanumerical information comprising a rotary metal
one of said electrodes and said rings when the characters
thereon representative of said value are in angular align
cylinder having a dielectric layer coated thereon for
sustaining electrostatic charges, a character recording sta
tion including a bank of stationary character heads ex
ment with said belt, said pulse Having an amplitude rais
ing the electric íield across said air gap above the critical 40 tending across said cylinder, each head including a row
stress value to effect a ñeld discharge in said gap and
of conductive point electrodes disposed in spaced rela
thereby `forming an electrostatic latent image of the
tion to said dielectric layer to deíine an air gap, means
to rotate said cylinder relative to said recording station,
means selectively to pulse said point electrodes during
tive to said drum to form successive lines of characters 45 movement of said cylinder in accordance with the value
of applied information to be recorded, said pulse having
thereon, charging means operatively disposed relative
selected characters on said belt at a position in accord
ance with said electrode, means to move said belt rela
to said belt in advance of said drum to pre-stress said
belt to a uniform potential, a developer section oper
an amplitude raising the electric field across said air gap
above the critical stress value to eifect a field discharge
across the gap thereby to form an electrostatic point
charge pattern on said layer simulating a character repre
atively disposed relative to said belt at a position be
yond said station to form powder images of said latent 50
sentative of said value, developer means to form powder
images, means operatively coupled to said belt to trans
images of said charge patterns, means to transfer said
fer said powder images onto a paper strip by electro
powder images to a paper strip by electrostatic attrac
static attraction, said last-named means including a paper
tion, and pre«stressing means Ato return said layer at a
strip movable in synchronism with said belt, a transfer
roller for eñìecting engagement between said strip and 55 uniform potential after said transfer operation.
said belt, and means to apply a potential to said trans
fer roller attracting said powder image to said strip.
7. Apparatus, as set forth in claim 6, further includ
ing means to fuse said powder image onto said strip.
ll. High-speed apparatus for recording and printing
alphanumerical information comprising a rotary metal
cylinder having a dielectric layer coated thereon for
sustaining electrostatic charges, a character recording sta
8. A high-speed apparatus for recording alphanumeri 60 tion including a bank of stationary character heads ex
tending across said cylinder, each head including a row
of conductive point electrodes disposed in spaced rela
cal information, said apparatus comprising a continuous
metal belt having an outer layer of insulating material
thereon for sustaining electrostatic charges, a rotary
tion to said dielectric layer to deñne an air gap, means
to rotate said cylinder relative to said recording station,
tive to said belt in spaced relation thereto to deñne an 65 means selectively to pulse said point electrodes during
movement of said cylinder in accordance with the value
electrostatic air gap, said drum having a bank of like
of applied information to be recorded, said pulse having
character rings thereon insulated from each other and a
an amplitude raising the electric ñeld across said air
bank of commutator rings each adjacent to and in elec
gap above the critical stress value to effect a ñeld dis
trical contact with a respective character ring, each ring
containing a series of character-shaped conductive elc 70 charge across the gap thereby to form an electrostatic
point charge pattern on said layer simulating a character
ments in a circumferential arrangement, the respective
representative of said value, developer means operatively
characters in the series being representative of different
disposed relative to said cylinder beyond said station to
values of incoming information, an array of ñXed elec
form powder images of said charge patterns, means in
trodes aligned with said commutator rings and spaced
therefrom to form a commutating air gap, and means 75 cluding a charged transfer roller to transfer said powder
character drum supported substantially transversely rela
11
images to a paper strip by electrostatic attraction, pre
stressing means in advance of said station to return said
layer at a uniform potential after said transfer operation,
and rotary brush means in advance of said pre-stressing
means to clean said cylinder of residual powder.
12. High-speed apparatus `for recording and printing
alphanumerical information comprising a rotary metal
cylinder having a dielectric layer coated thereon for
sustaining electrostatic charges, a character recording sta
tion including a bank of stationary character heads eX
tending across said cylinder, each head including a rec
tangular array of conductive point electrodes in spaced
relation to said dielectric layer to define an air gap, said
array being formed by parallel rows of pins, means to
rotate said cylinder relative to said recording station,
means selectively to pulse said pins in accordance with
the value of applied information to be recorded, said
pulse having an amplitude raising the electric field across
12
from said surface to form an air gap therebetween, elec
trostatic images of said character forming elements be
ing produced on said surface when voltages are applied
to said character forming elements relative to said back
ing elements effecting a field discharge in said air gap,
means operatively disposed with respect to said medium
beyond said station to form powder images of said latent
images, and means operatively coupled to said medium
to transfer said powder images onto a printing surface
by electrostatic attraction, said printing surface being
formed of a material having a resistivity which is low
relative to that of said recording medium.
15. An electrostatic apparatus, as set forth in claim
14, wherein said recording medium has a surface formed
by a flexible plastic and said printing surface is formed
of paper.
`
16. An electrostatic apparatus, as set forth in claim
14, wherein said recording medium is formed of a coated
said air gap above the critical stress value to effect a
paper, which coating imparts high resistivity thereto, and
field discharge across the gap thereby to form an electro 20 said printing surface is formed of uncoated paper.
static point charge pattern on said layer simulating a
character representative of said value, developer means
to form a powder image of said charge pattern, means
to transfer said powder images by electrostatic attrac-
17. An electrostatic apparatus for recording and print~
ing alphanumerical information at high speed, said ap
paratus comprising a movable endless recording medium
having an insulating surface of high resistivity for sus
tion to a paper strip, and means to erase said charge 25 taining electrostatic charges, a character forming station
pattern before said cylinder reaches said station.
including a conductive character forming element sup
13. An electrostatic apparatus for recording and print
ported relative to one side of said surface, a conductive
ing alphanumerical information at high speed, said ap
backing element supported relative to the other side of
paratus comprising a movable endless recording medium
said surface, one of said elements being spaced from
having an insulating surface of high resistivity _for sus
said surface to form an air gap therebetween, electro
taining electrostatic charges, a character forming station
static images of said character forming element being
including a set of conductive character forming elements
supported relative to one side of said surface, a set of
conductive backing elements supported relative to the
other side of said surface, one of said sets being spaced
from said surface to form an air gap therebetween, elec
trostatic images of said character forming elements be
ing produced on said surface when voltages are ap
plied to said character forming elements relative to said
backing elements effecting a field discharge in said air 40
gap, means operatively disposed with respect to said
medium beyond said station to form powder images of
said latent images, and means operatively coupled to
said medium to transfer said powder images onto a print
45
ing surface by electrostatic attraction.
14. An electrostatic apparatus for recording and print
inc' alphanumerical information at high speed, said ap
paratus comprising a movable endless recording medium
having an insulating surface of high resistivity for sus
taining electrostatic charges, a character forming station
including a set of conductive character forming elements
produced on said surface when a voltage is applied
thereto relative to said backing element effecting a field
discharge in said air gap, means operatively disposed
with respect to said medium beyond said station to form
powder images of said latent images, and means op
eratively coupled to said medium to transfer said powder
images onto a printing surface by electrostatic attraction.
References Cited in the file of this patent
UNITED STATES PATENTS
1,865,610
2,715,360
2,726,940
2,777,745
2,825,814
1932
1955
1955
1957
1958
FOREIGN PATENTS
1,112,180
734,909
France ______________ „_ Nov. 9, 1955
Great Britain _________ W Aug. 10, 1955
OTHER REFERENCES
supported relative to one side of said surface, a set of
conductive backing elements supported relative to the
other side of said surface, one of said sets being spaced
Blair _________________ _- July 5,
Brown ______________ __ Aug. 16,
Buhler ______________ __ Dec. 13,
McNaney ___________ __ Jan. 15,
Walkup _____________ __ Mar. 4,
General Electric Review, July '1952, pp. 20, 2l, 22 and
61.
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