U.S. patent number 3,655,280 [Application Number 04/595,153] was granted by the patent office on 1972-04-11 for xerographic fusing method and apparatus.
This patent grant is currently assigned to Xerox Corporation. Invention is credited to Raymond C. Zoppoth.
United States Patent |
3,655,280 |
Zoppoth |
April 11, 1972 |
XEROGRAPHIC FUSING METHOD AND APPARATUS
Abstract
This invention relates generally to xerographic method and
apparatus for reproducing information on materials such as
photographic film or the like and more particularly to method and
apparatus for fusing electroscopic powder images to materials such
as processed film and the like having photographic images thereon.
The invention is characterized in that electroscopic powder images
are fused to film material by exposing the images film material to
selected wavelengths of radiation which are transmitted by an
optical filter interposed between the film material and an
intermittently activated source of short duration high intensity
electromagnetic radiations.
Inventors: |
Zoppoth; Raymond C. (Pittsford,
NY) |
Assignee: |
Xerox Corporation (Rochester,
NY)
|
Family
ID: |
24381957 |
Appl.
No.: |
04/595,153 |
Filed: |
November 17, 1966 |
Current U.S.
Class: |
399/337; 392/417;
399/177; 219/216 |
Current CPC
Class: |
G03G
15/201 (20130101) |
Current International
Class: |
G03G
15/20 (20060101); G03g 015/00 () |
Field of
Search: |
;355/3 ;219/216 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Horan; John M.
Claims
What is claimed is:
1. Apparatus for xerographically reproducing information on
materials such as film or the like comprising:
a photoconductive member adapted to receive input information,
drive means for advancing said photoconductive member through a
series of processing stations,
charging means for applying a uniform electrostatic charge on said
photoconductive member,
exposure means for exposing and forming electrostatic latent images
on said photoconductive member in accordance with the input
information,
means for developing said latent electrostatic images,
transport means for advancing a film web containing image frames
thereon,
means for actuating said exposure means in a timed relationship
with the advancement of said film web,
means for transferring developed electrostatic images from said
photoconductive member to said film web,
a source of electromagnetic radiation adapted when energized to
direct high intensity short duration radiations toward said
electrostatic images on said film web,
circuit means for providing actuating signals to said source of
electromagnetic radiation,
cam actuated switch means for activating said circuit means in a
timed relationship with the advancement of said photoconductive
member, and
means interposed between said source of electromagnetic radiation
and said electrostatic images on said film web for filtering out
wavelengths of radiation within a selected range emitted by said
source.
2. The apparatus as set forth in claim 1 wherein said means
interposed between said source and said film web includes an
optical filter adapted to reflect wavelengths of radiation which
produce excessive heating of said film web and to uniformly
transmit wavelengths of radiation sufficient to fuse said
electrostatic images to said film web without producing excessive
heating of said film web.
3. Apparatus for flash fusing electroscopic powder images on
photographically processed films or the like comprising:
a source of electromagnetic radiation,
a housing surrounding said source,
means for advancing film material having electroscopic powder
images thereon past said housing in close proximity to said
source,
means for intermittently activating said source to produce short
duration high intensity electromagnetic radiations,
means for exposing said film material to electromagnetic radiations
emitted by said source, and
means interposed between said source and said film material for
selectively controlling the wavelengths of radiation to which the
film material and powder images are subjected.
4. Apparatus for xerographically reproducing information on
materials such as film or the like comprising:
a photoconductive member adapted to receive input information,
drive means for advancing said photoconductive member through a
series of processing stations,
charging means for applying a uniform electrostatic charge on said
photoconductive member,
exposure means for exposing and forming electrostatic latent images
on said photoconductive member in accordance with the input
information,
means for developing said latent electrostatic images,
transport means for advancing a film web containing image frames
thereon,
means for actuating said exposure means in a timed relationship
with the advancement of said film web,
means for transferring developed electrostatic images from said
photoconductive member to said film web,
a source of electromagnetic radiation adapted when energized to
direct high intensity short duration radiations toward said
electrostatic images on said film web,
circuit means for providing actuating signals to said source of
electromagnetic radiation,
cam actuated switch means for activating said circuit means in a
timed relationship with the advancement of said photoconductive
member, and
means interposed between said source of electromagnetic radiation
and said electrostatic images on said film web for filtering out
wavelengths of radiation including an optical filter adapted to
transmit wavelengths ranging from approximately 3,000 A to
approximately 8,000 A.
5. Apparatus for flash fusing electroscopic powder images on
photographically processed films or the like comprising:
a source of electromagnetic radiation,
a housing surrounding said source comprising means to expel
excessive heat generated by said radiation source,
means for advancing film material having electroscopic powder
images thereon past said housing in close proximity to said
source,
means for intermittently activating said source to produce short
duration high intensity electromagnetic radiations,
means for exposing said film material to electromagnetic radiations
emitted by said source, and
means interposed between said source and said film material for
selectively controlling the wavelengths of radiation to which the
film material and powder images are subjected comprising an optical
filter adapted to reflect wavelengths ranging from approximately
7,500 A to approximately 17,000 A.
6. Apparatus for flash fusing electroscopic powder images to a
support means comprising:
means adapted to intermittently generate a source of
electromagnetic radiation, and
means adapted to selectively control the wavelengths emanating from
said source of electromagnetic radiation whereby said selected
wavelength radiation fuses said powder images to said support
means.
7. Apparatus for flash fusing electroscopic powder images to a
support means comprising:
means adapted to intermittently generate a source of
electromagnetic radiation having a short duration and high
intensity, and
means interposed between said source of electromagnetic radiation
and said support means adapted to selectively control the
wavelengths emanating from said source of electromagnetic radiation
whereby said selected wavelength radiation fuses said powder images
to said support means.
8. Apparatus for flash fusing electroscopic powder images to a
support means comprising:
means adapted to generate a source of electromagnetic radiation
having a short duration and high intensity,
means for advancing said support means in close proximity to said
source of electromagnetic radiation and in synchronism with the
actuation thereof, and
means adapted to selectively control the wavelength emanating from
said source of electromagnetic radiation whereby said selected
wavelength radiation fuses said powder images to said support means
in predetermined areas.
9. Apparatus for flash fusing electroscopic powder images on
photographically processed films or the like comprising:
a source of electromagnetic radiation,
a housing surrounding said electromagnetic radiation source,
means for advancing film material having electroscopic powder
images thereon past said housing in close proximity to said
electromagnetic radiation source,
means for intermittently activating said electromagnetic radiation
source to produce short duration high intensity electromagnetic
radiations,
means for exposing said film material to electromagnetic radiations
emitted by said electromagnetic radiation source, and
means interposed between said electromagnetic radiation source and
said film material comprising an optical filter adapted to reflect
wavelengths of radiation which produce excessive heating of said
film material and to uniformly transmit wavelengths of radiation
sufficient to fuse said electroscopic powder images to said film
material without producing excessive heating of said film material.
Description
After a photographic image has been produced on film it is often
desirable to add additional information such as titling, coding,
numbering, etc. In the past mechanical methods for adding
information have been employed such as stamping the film with
printing characters as the film is transported past a printing
station on a conveyor transport. This technique is time consuming
and requires laborious adjustments to insure proper registration
between the printing characters and the prearranged marking areas
on the film. This particular method has not proven entirely
satisfactory.
Another approach to the problem has been to expose the film to
superimposed identifying information simultaneously with the
initial exposure. Subsequent processing therefore produces both the
original subject matter and its identifying code simultaneously.
However, this approach has the disadvantage of not being able to
add information after the raw film stock has been processed.
Techniques for adding information after processing by other than
mechanical means have been employed. One such method includes
coating the emulsion in the marking areas with a protective coating
such as paraffin and impressing photoengraved dyes containing the
information onto the coating. This displaces the coating and
exposes the emulsion in image configuration. Thereafter the
emulsion is removed by allowing an etching agent such as sodium
hypochlorite to act upon the exposed parts of the emulsion. However
this approach has the disadvantage of being expensive and time
consuming in that additional processing is required.
Probably the most desirable and efficient approach has been the
utilization of the xerographic process. One such technique is
disclosed in Carlson patent U.S. Pat. No. 2,297,691, in which a
powder image of a thermoplastic resin is applied to the film in the
marking areas. While it is conventional to fuse xerographic images
to a support base by means of heat sufficient to soften the resin,
this fusing method has heretofore been unsatisfactory with the use
of film in which the film base is itself heat sensitive. In
practice it has been found that when fusing heat is applied, the
film emulsion is scorched and discoloration occurs, and the film
base may become warped and distorted. As a result when employing
xerography it has been necessary to utilize a solvent vapor which
plasticizes the powder image but which leaves the film base
unaffected. Because of the problems in handling a vapor and the
expendable nature of a vapor it is desirable to use alternative
methods to vapor fixing of powder images such as heat fusing.
Accordingly, it is an object of my invention to provide improved
method and apparatus for fusing electroscopic toner images rapidly
onto a film base without incurring damage to the film base.
It is another object of my invention to provide improved method and
apparatus for fusing electroscopic toner images rapidly onto a film
base without incurring damage to the previously formed images
contained thereon.
Another object of my invention is to provide improved method and
apparatus for flash fusing electroscopic toner images rapidly onto
a film base.
Another object of my invention is to provide improved method and
apparatus for fusing electroscopic toner images rapidly onto a film
base by effectively controlling the amount of radiation which is
applied to the toner images and film base.
These objects are attained by exposing a film base having
electroscopic powder images thereon to selected wavelengths of
radiation transmitted by an optical filter from an intermittently
activated source of short duration high intensity electromagnetic
radiations. Other objects of the invention will become readily
apparent to those skilled in the art when read in connection with
the following detailed description and drawings wherein:
FIG. 1 is a schematic sectional view of a drum type xerographic
machine illustrating one embodiment of the invention;
FIG. 2 is a diagrammatic sectional view of a flash fusing station
according to one embodiment of the invention, and
FIG. 3 is a diagram of curves showing the spectral output of a
Xenon flash lamp with quartz envelope, toner absorptivity, the
filtering effects of a dichroic filter, and the transmittance of
another type of glass which may be used for the envelope of the
flash lamp.
FIG. 1 illustrates one embodiment of an apparatus utilizing a
controlled flash fusing technique. As shown therein referenced
information is recorded on a film web 10 to identify image frames
thereon. The information to be recorded is exposed to a uniformly
electrostatically charged xerographic drum generally designated 20
through exposure station 35 producing an electrostatic image of the
information. The image then contained on the drum is developed and
transferred to web 10 at transfer station 85. Thereafter the
transferred information is fused to the web at a fusing station
generally designated 148.
The automatic xerographic reproducing apparatus employed herein,
the detailed operation of which is more fully set forth in U.S.
Pat. No. 3,049,968, includes a xerographic drum 20 which is coated
on its outer surface with a layer of photoconductive insulating
material such as vitreous selenium and is rotated about its axis in
the direction of the arrow by a motor 25.
A charging apparatus 33 is provided for placing an initial charge
on the drum 20. Charging apparatus 33 may comprise an array of one
or more corona discharge electrodes extending transversely across
the surface of drum 20 and energized from a high potential
source.
Exposure station 35 may include a master film strip 38 containing
information to be recorded, flash lamp 39, lens 41, and aperture
40. Film strip 38 is supported between a supply reel 43 and a
takeup reel 42 which is intermittently driven by stepping motor 45.
Both lamp 39 and motor 45 are energized by signals from pulse
former 50 which receives an input signal responsive to the advance
of web 10 as will be hereinafter more fully explained. The signals
are synchronized so as to energize motor 45 and advance film strip
38 after each exposure from flash lamp 39. The particular
information contained in a given frame of film strip 38 is
illuminated by a flash from lamp 39 and through lens 41 and
aperture 40 is projected onto xerographic drum 20, thereby exposing
the drum.
As the drum 20 is rotated, exposed portions thereon are developed
at developing station generally designated 70. A conveyor 81
operating in housing 82 lifts developer material 83 from a supply
at the bottom of the housing to above drum 20 and releases it onto
the drum over which the developer material cascades until returning
to the bottom of housing 82. The developer material preferably
comprises a mixture of relatively large carrier particles and small
carbon black pigmented thermoplastic resin toner particles as
described in U.S. Pat. Re. No. 25,136. As developer material 83
cascades over the drum, the toner particles are detached from the
carrier particles and deposited onto the surface in accordance with
the latent images thereon thus forming visible images.
Continued rotation of drum 20 advances the developed images thereon
to transfer station, generally designated 85, at which the
electroscopic powder images are transferred to web 10. At the
transfer station web 10 is held in contact with drum 20 by a pair
of pressure rollers 86 and 87. A second corona charging device 88,
similar to corona charging device 33, places a transfer charge on
the web effecting the transfer thereto.
A drum cleaning and discharge station, generally designated 90, is
provided for cleaning and discharging the drum after transfer. A
pair of cleaning brushes 92 driven by a synchronous motor 94 remove
any toner particles remaining on the drum. A source of illumination
95 exposes the drum thereby dissipating any residual charge
remaining thereon prior to commencing the next cycle.
Transport assembly, generally designated 30, serves to
systematically advance film web 10 thereby insuring transfer of the
developed images in registration with the appropriate marking areas
along the film. Web 10 is advanced from supply spool 101 to a
takeup spool 107 by means of a motor 25'. Between supply spool 101
and pressure roller 86, the web 10 passes over idler sprocket 121,
or other suitable friction drive means rotatably mounted on shaft
123. Timing disc 135 having a diameter somewhat larger than that of
idler sprocket 121 is mounted in juxtaposition and rotatable
therewith. A plurality of apertures 138 in uniform angular
relationship are radially spaced about timing disc 135. Axially
disposed on opposite sides of timing disc 135 is a lamp 136 and a
photocell 137. Lamp 136 and photocell 137 are positioned such that
radiation emitted from lamp 136 may be received by photocell 137
through apertures 138. The angular spacing of apertures 138 about
timing disc 135 corresponds to the spacing between marking areas on
web 10. Thus as web 10 is advanced, sprocket 121 and timing disc
135 rotate, thereby intermittently aligning an aperture 138 with
lamp 136, and photocell 137. A signal thus received by photocell
137 from lamp 136 is transmitted to pulse former 50 which generates
a pulse thereby energizing lamp 39. This timing arrangement insures
synchronized exposure of the drum 20 with advancement of the web
10.
After transfer, web 10, having an image thereon, is advanced to
fusing station 148 located intermediate pressure roller 87 and
takeup reel 107.
With reference to FIG. 2, fusing station 148 includes lamp 151, a
housing comprised of a reflector portion 235 and a base portion
236, and filter 152.
Flash lamp 151 may be of a type which when energized produces
electromagnetic radiations. Typical flash lamps which are
commercially available and are suitable for this purpose are filled
with a gas such as Xenon, Argon, mercury or mixtures thereof. Such
lamps are capable of emitting radiation outputs of wavelengths in
the range of 2,000 angstroms to 24,000 angstroms. In practice a
Xenon flash lamp has been found to work particularly well. Normal
pulse widths for this lamp are on the order of from 100
microseconds to 2 milliseconds to provide the high repetition
discharge rate desired. Operating voltages suitable for this
purpose range from about 800 volts to about 2,500 volts. The
spectral curves available for this particular lamp start at about
2,000 angstroms and extend to about 18,000 angstroms peaking in the
short infrared range or at about 8,000 angstroms.
The particular lamp illustrated may comprise a gas filled quartz
tube containing two electrodes 154 and 155, one sealed at each end
thereof. To energize the lamp there is provided a trigger coil 153
encircling lamp 151 intermediate the two electrodes. Trigger coil
153 is coupled to a trigger circuit 160, such as a simple relay
circuit or controlled rectifier circuit, which when activated
provides a suitable high voltage pulse to the trigger coil 153.
This pulse through the coil 153 generates a high magnetic field in
the lamp thereby causing ionization of the gas within, between
electrodes 154 and 155 to which is applied a potential. The
potential applied to electrodes 154 and 155 is obtained from a 110
volt AC power supply which is stepped up by transformer 157 and
then rectified in a bridge rectifier 158. Capacitor 165 is charged
to an initial potential dependent on the parameters of the circuit,
prior to ionization of the gas in lamp 151. Upon ionization, the
lamp presents a low impedance across the electrodes 154 and 155
thereby striking a conductive arc discharging capacitor 165. In
practice a pulse forming circuit which produces a slow rise time
with fast cutoff after peak, produces a flash in the lamp which is
acceptable for fusing the toner images on the film. After discharge
of capacitor 165 the gas in lamp 151 deionizes allowing a charge to
be stored again in capacitor 165. Switch 181 is coupled to trigger
circuit 160 for actuating the flash lamp 151. A multi-lobe cam 180
rotates in synchronism with drum 20 which cam actuates switch 181.
The spacing between cam lobes 185 is such as to provide triggering
pulses in timed relationship with the advancement of drum 20 and
film web 10.
Flash lamp 151 is enclosed in housing 238 comprising reflector
portion 235 and base portion 236. An optical filter 152 overlays
aperture 230 in base portion 236 of the housing to selectively pass
only radiations from lamp 151 within a desired range of wavelengths
as will be hereinafter more fully explained. Excess heat within the
housing which may be generated by reflected wavelengths of
radiation may be removed by means of a steady stream of air
circulated past lamp 151 from an air conduit 250 located at one end
of the housing which is connected to a compressed air source (not
shown). An exhaust opening 250' at the opposite end of the housing
may be provided to allow the heated air within to escape.
FIG. 2 illustrates a cross section of film web 10 at the fusing
station which is comprised of a base layer 212, an emulsion 215
having been photographically processed to develop images therein
and the electrostatically bound images 220 transferred thereto at
transfer station 85.
Base layer 212 may be comprised of any suitable material, such
material including cellulose triacetate, estar, or cellulose
acetate butyrate. The particular emulsion 215 on base layer 212 may
likewise be comprised of any suitable material, silver halide being
that which is most commonly utilized. Usually it is customary for
the electrostatically bound images 220 to be placed along one edge
of the film web, or adjacent to sprocket holes 240 if a web having
such holes is utilized. It should be understood, however, that the
toner image may be placed elsewhere on the web so long as the image
areas are in the emission path emanating from the lamp. In any
event the web is transported over the fusing station such that the
images 220 are exposed to the selected wavelengths of radiation
transmitted by filter 152.
Filter 152 may be comprised of any suitable material which is
adapted to reflect wavelengths of radiation in a specified range
and to uniformly transmit wavelengths of a specified range.
While the characteristics of reflectivity, absorptivity, and
transmissivity respective to the film base, emulsion and toner
particles are not specifically known, it has been found that the
relative values thereof are such as to obtain good fusion of the
toner particles from wavelengths of radiation in the range of
3,000-8,000 angstroms without deleterious effects to the film base
or emulsion.
In practice it has been found that without selective control of the
wavelengths utilized, fusing of the toner particles is obtained
during the short duration of lamp exposure, on the order of 1
millisecond, but scorching or bleaching of the emulsion occurs. On
the other hand by utilizing the filter which selectively controls
or reflects radiations having wavelengths longer than approximately
8,000 angstroms, fusion of the toner particles is obtained during
the same duration of lamp exposure without bleaching or scorching
the emulsion or adversely affecting the film base.
These results may be attributable to several factors. In practice,
the film base is believed to have a high reflectivity to incident
radiation whereas the toner particles are believed to have a low
reflectivity. That is, the fraction of the incident radiation
reflected from the surface of the film base is greater than that
for the toner particles. The reflectivity of the dense dark
emulsion areas likewise is believed to be relatively high but to a
somewhat lesser extent perhaps than the unemulsified film base. The
transmissivity of the film base is also believed to be greater than
that of the toner particles. That is, the fraction of the incident
radiation transmitted through the film base is greater than that
transmitted through the toner particles. The transmissivity of the
dark emulsion areas is also believed lower than that of the film
base but perhaps greater than the toner particles. In addition, the
film base is believed to have a very low absorptivity whereas the
toner particles thereon have a relatively high absorptivity more
nearly approaching that of a theoretical black body. That is to
say, more of the incident radiant energy falling upon the toner
particles is absorbed, or transformed into heat, than occurs in the
film base. The absorbtivity of the dark or dense areas of the
emulsion are likewise believed to be relatively high but to a
lesser extent than that for the toner particles. It would appear
therefore that a greater amount of heating occurs in the toner
particles than in the emulsion or the film base since more
radiation is absorbed by the toner particles than by the emulsion
or by the film base.
It is generally known that the longer wavelengths of radiation
produce a greater amount of heating in most absorbing bodies than
do the shorter wavelengths. By controlling the wavelengths of
radiation to which the toner particles, film base, and emulsion are
subjected, the toner particles absorb radiation sufficient to
produce heating to the point of fusion but the radiation absorbed
by the film base and emulsion is insufficient to effect heating to
the point of damaging or deleteriously affecting either the
emulsion or film base in exposed areas.
Numerous optical filters are commercially available which are
designed to selectively transmit only radiations in a particular
range. A commercially available dichroic filter has been utilized
with effective results. As shown in FIG. 3, the spectral output of
the Xenon flash lamp with a quartz envelope ranges from about 2,000
to 18,000 angstroms, peaking in the short infrared range or at
about 8,000 angstroms. The glass transmittance curve illustrates
the spectral transmittance of another type of glass which may be
used for the envelope of the flash lamp which does not transmit
wavelengths below approximately 3,000 angstroms. The area under the
dichroic filter curve illustrates that portion of the spectrum
which is reflected by the filter ranging between approximately
8,000 and 16,000 to 17,000 angstroms. Although filters such as the
dichroic filter do not reflect all wavelengths above approximately
8,000 angstroms, they nevertheless reflect all wavelengths in the
upper ranges of an intensity sufficient to have deleterious effects
on the film. The radiations emitted by the lamp above approximately
16,000 to 17,000 angstroms, which are beyond the capacity of the
filter, are of such low intensity as to have no adverse effect on
the film base or emulsion. As may be further observed from FIG. 3,
the spectral output of the Xenon flash lamp which is utilized to
effect fusing, ranges from about 3,000 angstroms to about 8,000
angstroms.
Thus, it may be seen that by the above description there is
disclosed a novel method and apparatus for flash fusing xerographic
images onto a film base without adversely affecting the image
frames or emulsion contained thereon, and that this may be
accomplished by selectively controlling the wavelengths of
radiation to which the film base, the emulsion, and the toner
images are subjected.
While the invention has been described with reference to the
structure disclosed herein, it is not confined to the details set
forth, and this application is intended to cover such modifications
or changes as may come within the purposes of the improvements or
the scope of the following claims:
* * * * *