This invention relates generally to color imaging and more particularly
to a method and apparatus for producing simulated photographic prints using xerography.
In the practice of conventional xerography, it is the general procedure
to form electrostatic latent images on a xerographic surface by first uniformly
charging a charge retentive surface such as a photoreceptor. The charged area is
selectively dissipated in accordance with a pattern of activating radiation corresponding
to original images. The selective dissipation of the charge leaves a latent charge
pattern on the imaging surface corresponding to the areas not exposed by radiation.
This charge pattern is made visible by developing it with toner by
passing the photoreceptor past a single developer housing. The toner is generally
a colored toner which adheres to the charge pattern by electrostatic attraction.
The developed image is then fixed to the imaging surface or is transferred to a
receiving substrate such as plain paper to which it is fixed by suitable fusing
techniques.
Recently, there has been a great deal of effort directed to the development
of color copiers/printers which utilize the xerographic process. Such efforts have
resulted in the recent introduction of the Xerox 5775 copier/printer and the Fuji
Xerox A-Color 635 copier/printer.
The quality of color xerographic images on paper has approached the
quality of color photographic prints. However, color xerographic prints fall short
because they do not have the uniform gloss, the wide density range or the brilliance
typical of photographic prints. Nor do xerographic prints have the feel of photographic
prints because the paper usually used is too lightweight and too limp.
Typically the surface of color toner images is irregular or rough
or rather lumpy. The behavior of incident white light vis-a-vis such color images
is believed to be as follows:
   Some of the white light incident on the substrate carrying
the color toner images specularly reflects off the substrate;
   Some of the light goes down into the paper, scatters around
and comes back out in various directions, some through the toner and some not;
   Because the toner surface is rough or irregular some of the
light incident thereon is reflected off the toner in various directions.
   Some of the light incident on the irregular toner surfaces
passes through the toner into the paper and comes back out in various directions.
White light becomes colored due to selective absorption as it passes
through toner. The light then goes down into the paper and back out through the
toner where it becomes more colored. As will be appreciated, any white light which
does not pass through the toner diminishes the appearance of the final print.
Attempts to make up this deficiency in conventionally formed color
toner images have led to the lamination of xerographic images on paper using a
transparent substrate. This procedure has been only partially successful because
the lamination process tends to reduce the density range of the print resulting
in a print that has less shadow detail. The lamination process also adds significant
weight and thickness to the print.
Additionally, it is believed that the reason that the aforementioned
lamination process does not produce good results resides in the fact that typically
the color toner images at the interface between the laminate and the toner do not
make suitable optical contact. That is, the toner image at the interface is still
irregular (i.e. creating voids) enough after lamination that light is reflected
from at least some of those surfaces and is precluded from passing through the
toner. In other words, when there are voids between the transparency and toner
image, light gets scattered and reflected back without passing through the colored
toner. Loss of image contrast results when any white light is scattered, either
from the bottom surface of the transparent substrate or from the irregular toner
surfaces and doesn't pass through the toner.
A known method of improving the gloss of color xerographic images
on a transparent substrate comprises re-fusing the color images. Such a process
was observed at a NOMDA trade show in 1985 at a Panasonic exhibit. The process
exhibited was carried out using an off-line transparency fuser, available from
Panasonic as model FA-F100, in connection with a color xerographic copier which
was utilized for creating multi-color toner images on a transparent substrate for
the purpose of producing colored slides. Since the finished image from the color
copier was not really suitable for projection, it was re-fused using the aforementioned
off-line re-fuser. To implement the process, the transparency is placed in a holder
intermediate which consists of a clear relatively thin sheet of plastic and a more
sturdy support. The holder is used for transporting the imaged transparency through
the off-line re-fuser. The thin clear sheet is laid on top of the toner layer on
the transparency. After passing out of the re-fuser, the transparency is removed
from the holder. This process resulted in an attractive high gloss image useful
in image projectors. The re-fuser was also used during the exhibit for re-fusing
color images on paper. However, the gloss is image-dependent. Thus, the gloss is
high in areas of high toner density because the toner re-fuses in contact with the
clear plastic sheet and becomes very smooth. In areas where there is little or
no toner the gloss is only that of the substrate.
The following is a discussion of prior art which may be relevant to
the patentability of the present invention:
U.S-A-4,686,163 and U.S-A-4,600,669 describe an electrophotographic
imaging method that uses an element comprising a photoconductive layer on an electrically
conducting substrate capable of transmitting actinic radiation to which the photoconductive
layer is responsive, and a dielectric support, releasably adhered to the substrate,
comprising the photoconductive layer or an overcoat thereof forming a surface of
the element capable of holding an applied electrostatic charge. To use the element,
the surface of the dielectric support is charged, and the photoconductive layer
is imagewise-exposed to actinic radiation, thereby forming a developable electrostatic
image on the dielectric surface. The electrostatic image, in turn, is developed
with toner to form a first color image. A composite color image is formed on the
element by repeating the sequence one or more times with imagewise exposure of
the photoconductive layer to actinic radiation transmitted through the substrate,
and developing over each preceding image with a different color toner. The composite
toner image is transferred with the dielectric support to a receiving element to
form a color copy such as a three-color filter array or a color proof closely simulating
the color print expected from a full press run.
The dielectric support on the photoconductive layer comprised a transparent
blend of poly (vinylacetate-co-crotonic acid, 95/5 mole ratio) and cellulose acetate
butyrate. The resulting multicolor proof presented a multicolor toner image against
a white paper background and protected by the overlying dielectric support, thus
accurately resembling a multicolor print from a full press run.
The receiver element to which the dielectric support and composite
toner image are transferred can be any suitable material against or through which
the toner image is desired to be viewed. The receiver can be print stock, such
as paper, upon which a press run will be conducted. The receiver can also be of
transparent material such as a polymeric film. With respect to the latter, the
invention also contemplates, as an embodiment, transfer of the composite toner
image and dielectric support to image-bearing elements such as microfilm or microfiche
so that the composite color image forms information in addition to image information
already present on such image-bearing elements in addition, the invention contemplates
the use of transparent glass or nonbirefringent translucent polymeric materials
such as cellulose esters for use as the receiver. Receivers manufactured from such
materials are suited for use in forming three-color filter arrays by the process
described herein involving the formation of filter array matrices of the complementary
colorants cyan, magenta and yellow in the respective color toner imaging steps.
If desirable, the receiver can also contain a suitable overcoat layer adapted to
soften under the influence of pressure and heat during the transfer step. In this
manner, the adhesion of the dielectric support and composite toner image to the
receiver can be enhanced.
The electrophotographic element bearing the multicolor toner image
is moved to a separate lamination device comprising heated metal and rubber rolls,
together forming a nip. The toner image is passed through the nip with and against
a white receiver paper at a roll temperature of 100° C (212° F) and a pressure
of 225 pounds per square inch (1.551 MPa) to effect transfer of the dielectric
support and composite image to the receiver followed by peeling off the rest of
the electrophotographic element.
U.S.-A-4,066,802 granted on January 3, 1978 to Carl F. Clemens discloses
a method of decalcomania in which a toner image pattern is formed on a transfer
member which has been overcoated with an abhesive material. A polymeric sheet is
interposed between the toner image and a cloth or other image receiving medium.
The polymeric sheet assists in the permanent adherence of the toner imaging pattern
to the cloth material or other medium when the composite is subjected to heat and
pressure. The transfer member and method of its use are set forth. Another embodiment
discloses the use of solvent to fix the image to a cloth material.
U.S.-A-5,065,183 granted on November 12, 1991 to Morofuji et al discloses
a multicolor printing method for printing multicolor picture images upon a material
or object to be printed comprising the steps of, in accordance with a first embodiment,
the formation of a multicolor toner image upon a flexible belt by means of electrophotographic
printing methods or techniques, and the transfer of such multicolor toner image
directly to the material or object to be printed, such as, for example, a container
made of, for example, metal, paper, plastic, glass, or the like, by means of a
thermo-transferring process. In accordance with a second embodiment, the multicolor
toner image is formed upon a plastic film, which is laminated upon the flexible
belt, by means of electrophotographic printing methods or techniques, and the plastic
film is then transferred to and fused upon the container. In accordance with a third
embodiment, a photoconductive member is irradiated by means of exposure light upon
a rear surface thereof wherein the multicolor picture images are also formed by
electrophotographic printing methods or techniques. In this manner, previously
formed toner images upon the photoconductive member do not interfere with the image
exposure processing.
U.S.-A-5,126,797 granted on June 30, 1992 to Forest et al discloses
a method and apparatus for laminating toner images wherein a toner image on a receiving
sheet is laminated using a transparent laminating sheet fed from the normal copy
sheet supply of a copier, printer or the like. The laminating sheet is fed into
laminating contact with the toner image after the toner image has been formed on
a receiving sheet. The resulting sandwich is fed through the fuser laminating the
image between the sheets. The method is particularly usable in forming color transparencies.
U.S.-A-5,108,865 granted to Zwaldo et al on April 28, 1992 discloses
a method including the steps of:
   contacting an image (preferably multi-toned image) with a transfer
web (intermediate receptor layer) comprising in sequence, a carrier layer, a transferable
release layer, and a releasable adhesive layer (releasable from the carrier layer
along with the transferable release layer so that both layers transfer at once),
said adhesive layer being in contact with said toned image, said contacting being
done under sufficient heat and/or pressure to enable said toned image to be adhered
to said releasable adhesive layer with greater strength than the adherence of said
toned image to said imaging surface of said photoconductive layer;
   separating the transfer web and said photoconductive layer
so that the toned image is removed from said photoconductive layer and remains
adhered to the adhesive layer of the transfer web;
   contacting the surface of the transfer web having both the
multi-toned image and adhesive thereon with a permanent receptor surface;
   adhering the adhesive on the transfer web to the permanent
surface; and
   removing the carrier layer of the transfer web from the adhesive
and the release layer of the transfer web so that an image article is formed of
the permanent receptor, multi-toned image, releasable adhesive, and the resultant
surface coating of the release layer which is furthest away from the permanent
receptor.
U.S.-A-4,949,103 granted to Schmidlin et al on August 14, 1990 discloses
a direct electrostatic printing (DEP) device utilized for printing mirror or reverse/wrong
reading toner images on a transparent substrate. An adhesive coating on the transparent
substrate on the toner image side thereof enables the transparent substrate to
be affixed to substrate such as an envelope such that the mirror images are right
reading.
U.S.-A-4,868,049 and U.S.-A-4,724,026 granted to Marshall A. Nelson
on September 19, 1989 and February 9, 1988, respectively, disclose selective metallic
transfer foils for selectively transferring metallic foil to xerographic images
on a receiving substrate such as paper. The transfer sheet comprises, in successive
layers, a carrier film, a metallic film and an adhesive, the adhesive containing
a dispersion of 0.5 micron or larger particulate material. A method is disclosed
for forming images overlaid with metallic foil. In this method, a sheet comprising
xerographic images is provided and placed in face-to-face contact with a metal
transfer sheet, to form a sandwich with the xerographic images on the inside. Heat
and pressure are applied to the sandwich, causing the xerographic images to become
tacky and causing the metallic foil to selectively adhere to the images. The remainder
of the transfer sheet is then stripped away from the resulting decorated sheet
comprising xerographic images overlaid with metallic foil. In the preferred embodiment,
the metal transfer sheet is provided with an adhesive of high filler content resin
which has been found to produce good quality transfers to xerographic images produced
by a wide variety of toners and photocopy machinery.
U.S.-A-3,914,097 granted to Donald R. Wurl on Oct. 21, 1975 discloses
a sheet guide and cooling apparatus for preventing curl in sheets bearing a developed
image, the image being permanently fixed to the sheet by application of heat and
pressure. The apparatus is positioned to have a flat thermally conductive surface
establishing a path for the sheet, downstream of the fixing area, the path extending
in a plane substantially coplanar with the plane of sheet travel in the fixing
station. Vacuum means associated with the surface maintains successive incremental
portions of a sheet in face-to-face contact with the flat surface as it is being
guided for at least a predetermined period as the sheet moves along the path and
furthermore, provides a flow of cooling air for the surface.
U. S. Patent Application Serial No. (Attorney's Docket No. D/93231)
filed on the same date as the instant application discloses a device for creating
simulated photographic prints using the xerographic process. As disclosed therein,
light reflecting sheet is bonded to a transparent substrate containing a xerographically
formed toner image. The sheet and transparent substrate are held in a flat condition
while applying heat and pressure for effecting the aforementioned bonding. The
sheet and substrate are supported on a piece of tempered glass during the bonding
process.
U.S. Patent Application, Serial No. (Attorney's Docket No. D/93279)
filed on the same date as the instant application discloses a kit for creating
simulated photographic prints using xerographic imaging. The kit comprises a transparent
carrier suitable for having a reverse reading toner image fused thereto and a reflective
backing sheet, the latter of which is coated with a heat activatable adhesive material
for bonding the latter to the former. The kit further includes a rigid surface
of tempered glass upon which the transparent substrate is supported during bonding.
An abhesive member is provided for covering the transparent carrier during the
process of making prints.
The primary object of the present invention is to create simulated
color photographic prints using xerography wherein the print has the look and feel
of a conventional color photograph. Additionally, it is an object of the present
invention to improve the contrast of simulated photographic prints created using
the xerographic process.
According to the present invention, there is provided a method of
creating simulated photographic prints using xerographic imaging, including the
steps of:
   forming a light reflecting layer over one or more xerographically
formed mirror images fused to a transparent substrate.
The step of forming a light reflecting layer may comprise applying
a light color film, such as a white glue. The white glue may be provided on a backing
sheet.
Alternatively, the step of forming a light reflecting layer may comprise
adhering a backing sheet to the transparent substrate.
This invention also comprises an apparatus for creating simulated
photographic prints using xerographic images on a transparent substrate, said apparatus
comprising:
   means for transporting a transparent substrate having mirror
images on one surface thereof from a printer to a simulated print making processor;
   means for moving said one surface of the transparent substrate
and a reflective backing member into superimposed orientation;
   means for simultaneously applying heat and pressure to said
transparent substrate and said backing member thereby causing them to adhere to
each other to form a simulated photographic print.
Briefly, the present invention is carried out by first creating a
multi-color, reverse reading (or mirror) toner image on a transparent substrate.
The multi-color toner image is xerographically created by sequentially forming
different color toner images on the transparent substrate followed by the use of
heat and pressure or other suitable means to affix or fuse the multi-color image
to the transparent substrate such that there is good optical contact at the interface
between the transparent substrate and the toner. The toner carrying side of the
transparent substrate may then be bonded to a white or near white substrate to
provide a light colour backing sheet for effective reflection of light back through
the toner image. Alternatively, the toner carrying side of the transparent substrate
is bonded to a backing sheet after being coated with a light reflective coating
to form a simulated print which has the look and feel of an actual photographic
print. In either case, the transparent substrate may be coated with a suitable
resin for the purpose of enhancing the adherence of a glue deposited on the backing
sheet.
Satisfactory results have been obtained by placing a sheet of white
or near white plastic paper on the fused toner side of the transparent substrate
and passing a sandwich formed thereby through a heat and pressure roll fuser. Similarly,
satisfactory results have been obtained by applying a light reflective coating
such as a white or near white glue or toner over the toner image on the transparent
substrate. The transparent substrate is then adhered to the backing sheet by passing
a sandwich formed thereby through a heat and pressure roll fuser. In either case,
a plain sheet of paper may be placed in contact with the nonimaged side of the
transparent substrate during passage of the transparent substrate and backing sheet
through the roll pair to prevent degradation of the top surface of the print.
In the foregoing manner, the transparent substrate with the toner
image is adhered to a backing sheet to form a simulated photographic print. The
resulting print exhibits an attractive and brilliant appearance which is more fade
resistant and durable than commercially available photographic prints. Prints created
in the foregoing manner have the look and feel of photographic prints but appear
to have more brilliance. This is thought to be attributable to the xerographically
formed prints having a lesser minimum density than conventional photographic prints
resulting in whiter whites.
A further aspect of this invention is that exceptionally good quality
prints can be more quickly and more cost effectively produced than with conventional
photographic printing techniques, especially in the case of larger size prints.
Additionally, this process does not require silver, photographic chemicals, or
intermediary negatives even when a black and white print is created from a color
original.
Existing color xerographic copier/printer systems can be used for
the process. Thus, all the resources associated with these products, particularly
the ones which utilize state of the art electronic devices such as film scanners,
image composition enhancers, color adjusters and editors can be utilized.
A method and apparatus in accordance with the invention will now be
described, by way of example, with reference to the accompanying drawings, in which:-
Figure 1 is a side elevational view of an imaging apparatus and a
print processor.
Figure 2 is a modified embodiment of the imaging apparatus and print
processor.
Figure 3 is a side plan view of a heat and pressure roll arrangement
and the members used for creating simulated photographic prints using xerography.
Figure 4 is a perspective view of a color transfer member.
Figure 5 is a schematic illustration of an imaging apparatus suitable
for use of the present invention.
For a general understanding of the features of the present invention,
reference is made to the drawings. In the drawings, like references have been used
throughout to designate identical elements.
Figure 5 is a schematic elevational view of an illustrative electrophotographic
copier which may be utilized in carrying out the present invention. It will become
evident from the following discussion that the present invention is equally well
suited for use in a wide variety of printing systems, and is not necessarily limited
in its application to the particular system shown herein.
Turning initially to Figure 5, during operation of a printing system
9, a multi-color original document or photograph 38 is positioned on a raster input
scanner (RIS), indicated generally by the reference numeral 10. The RIS contains
document illumination lamps, optics, a mechanical scanning drive, and a charge
coupled device (CCD array). The RIS captures the entire original document and converts
it to a series of raster scan lines and measures a set of primary color densities,
i.e. red, green and blue densities, at each point of the original document. This
information is transmitted to an image processing system (IPS), indicated generally
by the reference numeral 12. IPS 12 contains control electronics which prepare and
manage the image data flow to a raster output scanner (ROS), indicated generally
by the reference numeral 16. A user interface (UI), indicated generally by the
reference numeral 14, is in communication with IPS 12. UI 14 enables an operator
to control the various operator adjustable functions. The output signal from UI
14 is transmitted to IPS 12. Signals corresponding to the desired image are transmitted
from IPS 12 to a ROS 16, which creates the output image. ROS 16 lays out the image
in a series of horizontal scan lines with each line having a specified number of
pixels per mm. ROS 16 includes a laser having a rotating polygon mirror block associated
therewith. ROS 16 is utilized for exposing a uniformly charged photoconductive
belt 20 of a marking engine, indicated generally by the reterence numeral 18, to
achieve a set of subtractive primary latent images. The latent images are developed
with cyan, magenta, and yellow developer material, respectively. These developed
images are transferred to a final substrate in superimposed registration with one
another to form a multi-color image on the substrate. This multi-color image is
then heat and pressure fused to the substrate thereby forming a multi-color toner
image thereon.
The printing system 9 is capable of printing conventional right reading
toner images on plain paper or mirror images on various other kinds of substrates
as will be discussed hereinafter. Mirror or reverse reading images on final substrates
are effected through programed use of the UI 14.
The features of the printing system hereinabove described are utilized
in the commercially available 5775 copier.
With continued reference to Figure 5, printer or marking engine 18
is an electrophotographic copier machine. Photoconductive belt 20 of marking engine
18 is preferably made from a polychromatic photoconductive material. The photoconductive
belt moves in the direction of arrow 22 to advance successive portions of the photoconductive
surface sequentially through the various processing stations disposed about the
path of movement thereof. Photoconductive belt 20 is entrained about transfer rollers
24 and 26, tensioning roller 28, and drive roller 30. Drive roller 30 is rotated
by a motor 32 coupled thereto by suitable means such as a belt drive. As roller
30 rotates, it advances belt 20 in the direction of arrow 22.
Initially, a portion of photoconductive belt 20 passes through a charging
station, indicated generally by the reference numeral 33. At charging station 33,
a corona generating device 34 charges photoconductive belt 20 to a relatively high,
substantially uniform electrostatic potential.
Next, the charged photoconductive surface is moved through an exposure
station, indicated generally by the reference numeral 35. Exposure station 35 receives
a modulated light beam corresponding to information derived by RIS 10 having a
multi-color original document 38 positioned thereat. RIS 10 captures the entire
image from the original document 38 and converts it to a series of raster scan
lines which are transmitted as electrical signals to IPS 12. The electrical signals
from RIS 10 correspond to the red, green and blue densities at each point in the
original document IPS 12 converts the set of red, green and blue density signals,
i.e. the set of signals corresponding to the primary color densities of original
document 38, to a set of colorimetric coordinates. The operator actuates the appropriate
keys of UI 14 to adjust the parameters of the copy. UI 14 may be a touch screen,
or any other suitable control panel, providing an operator interface with the system.
The output signals from UI 14 are transmitted to IPS 12. The IPS then transmits
signals corresponding to the desired image to ROS 16. ROS 16 includes a laser with
rotating polygon mirror block. Preferably, a nine facet polygon is used. ROS 16
illuminates, via mirror 37, the charged portion of photoconductive belt 20 at a
rate of about 16 pixels per mm. The ROS will expose the photoconductive belt to
record three latent images. One latent image is developed with cyan developer material.
Another latent image is developed with magenta developer material and the third
latent image is developed with yellow developer material. The latent images formed
by ROS 16 on the photoconductive belt correspond to the signals transmitted from
IPS 12.
After the electrostatic latent images have been recorded on photoconductive
belt 20, the belt advances such latent images to a development station, indicated
generally by the reference numeral 39. The development station includes four individual
developer units indicated by reference numerals 40, 42, 44 and 46. The developer
units are of a type generally referred to in the art as "magnetic brush development
units." Typically, a magnetic brush development system employs a magnetizable developer
material including magnetic carrier granules having toner particles adhering triboelectrically
thereto. The developer material is continually brought through a directional flux
field to form a brush of developer material. The developer material is constantly
moving so as to continually provide the brush with fresh developer material. Development
is achieved by bringing the brush of developer material into contact with the
photoconductive surface. Developer units 40, 42, and 44, respectively, apply toner
particles of a specific color which corresponds to a complement of the specific
color separated electrostatic latent image recorded on the photoconductive surface.
The color of each of the toner particles is adapted to absorb light within a preselected
spectral region of the electromagnetic wave spectrum. For example, an electrostatic
latent image formed by discharging the portions of charge on the photoconductive
belt corresponding to the green regions of the original document will record the
red and blue portions as areas of relatively high charge density on photoconductive
belt 20, while the green areas will be reduced to a voltage level ineffective for
development. The charged areas are then made visible by having developer unit 40
apply green absorbing (magenta) toner particles onto the electrostatic latent image
recorded on photoconductive belt 20. Similarly, a blue separation is developed by
developer unit 42 with blue absorbing (yellow) toner particles, while the red separation
is developed by developer unit 44 with red absorbing (cyan) toner particles. Developer
unit 46 contains black toner particles and may be used to develop the electrostatic
latent image formed from a black and white original document or in combination
with any or all of the color developer units. Each of the developer units is moved
into and out of an operative position. In the operative position, the magnetic
brush is closely adjacent to the photoconductive belt, while in the non-operative
position, the magnetic brush is spaced therefrom. In Figure 5, developer unit 40
is shown in the operative position with developer units 42, 44 and 46 being in
the non-operative position. During development of each electrostatic latent image,
only one developer unit is in the operative position, the remaining developer units
are in the non-operative position. This ensures that each electrostatic latent
image is developed with toner particles of the appropriate color without commingling.
It will be appreciated by those skilled in the art that scavengeless
or non-interactive development systems well known in the art could be used in lieu
of magnetic brush developer structures. The use of non-interactive developer systems
for all but the first developer housing would make it unnecessary for movement
of the developer housings relative to the photoconductive imaging surface.
After development, the toner image is moved to a transfer station,
indicated generally by the reference numeral 65. Transfer station 65 includes a
transfer zone, generally indicated by reference numeral 64. In transfer zone 64,
the toner image is transferred to a transparent substrate 25. At transfer station
65, a substrate transport apparatus, indicated generally by the reference numeral
48, moves the substrate 25 into contact with photoconductive belt 20. Substrate
transport 48 has a pair of spaced belts 54 entrained about a pair of substantially
cylindrical rollers 50 and 52. A substrate gripper (not shown) extends between
belts 54 and moves in unison therewith. The substrate 25 is advanced from a stack
of substrates 56 disposed on a tray. A friction retard feeder 58 advances the uppermost
substrate from stack 56 onto a pre-transfer transport 60. Transport 60 advances
substrate 25 to substrate transport 48. Substrate 25 is advanced by transport 60
in synchronism with the movement of substrate gripper 84. In this way, the leading
edge of substrate 25 arrives at a preselected position, i.e. a loading zone, to
be received by the open substrate gripper. The substrate gripper then closes securing
substrate 25 thereto for movement therewith in a recirculating path. The leading
edge of substrate 25 is secured releasably by the substrate gripper. As belts 54
move in the direction of arrow 62, the substrate moves into contact with the photoconductive
belt, in synchronism with the toner image developed thereon. At transfer zone 64,
a corona generating device 66 sprays ions onto the backside of the substrate so
as to charge the substrate to the proper electrostatic voltage magnitude and polarity
for attracting the toner image from photoconductive belt 20 thereto. The substrate
remains secured to the substrate gripper so as to move in a recirculating path
for three cycles. In this way, three different color toner images are transferred
to the substrate in superimposed registration with one another to form a composite
multi-color image 67. According to the invention, the composite toner image formed
on the photoconductive belt 20 is a right reading image so that after transfer
thereof, to a transparent substrate in a manner to be described hereinafter, the
image represents a wrong or reverse reading multi-color toner image when viewed
from the toner side and is right reading when viewed through the substrate.
The transparent substrate 25 preferably comprises transparent polyester
material such as Mylar, commercially available from E.I. DuPont. A suitable thickness
for the transparent substrate for use in forming simulated photographic prints
using the xerographic process described above is approximately 0.11mm (0.0042 inch).
The actual thickness of the transparent substrate will depend on the xerographic
processor which is used for making the color images on the transparent substrate.
An important characteristic of the substrate 25 is that its glass transition temperature
is substantially above that of the toner materials employed in creating the images
thereon.
One skilled in the art will appreciate that the substrate may move
in a recirculating path for four cycles when under color removal and black generation
is used and up to eight cycles when the information on two original documents is
being merged onto a single substrate. Each of the electrostatic latent images recorded
on the photoconductive surface is developed with the appropriately colored toner
and transferred, in superimposed registration with one another, to the substrate
to form a multi-color facsimile of the colored original document. As may be appreciated,
the imaging process is not limited to the creation of color images. Thus, high
quality black and white simulated photographic prints may also be created using
the process disclosed herein.
After the last transfer operation, the substrate gripper opens and
releases the substrate. A conveyor 68 transports the substrate, in the direction
of arrow 70, to a heat and pressure fusing station, indicated generally by the
reference numeral 71, where the transferred toner image is permanently fused to
the substrate. The fusing station includes a heated fuser roll 74 and a pressure
roll 72. The substrate passes through the nip defined by fuser roll 74 and pressure
roll 72. The toner image contacts fuser roll 74 and is affixed to the transparent
substrate. The fusing process effects an excellent optical interface between the
fused toner and the transparent substrate. Thereafter, the substrate is advanced
by a pair of rolls 76 to an outlet opening 78 through which substrate 25 is conveyed
to a processor to be discussed hereinafter.
The last processing station in the direction of movement of belt 20,
as indicated by arrow 22, is a cleaning station, indicated generally by the reference
numeral 79. A rotatably mounted fibrous brush 80 is positioned in the cleaning
station and maintained in contact with photoconductive belt 20 to remove residual
toner particles remaining after the transfer operation. Thereafter, lamp 82 illuminates
photoconductive belt 20 to remove any residual charge remaining thereon prior to
the start of the next successive cycle.
The transparency 25 having the composite, reverse reading color image
67 thereon is utilized in an off-line processor 90 (Figure 1) for creating a simulated
color photographic print. In one mode of operation, the transparencies 25 are fed
from the printing system 9 through the outlet opening 78 and inverted using an
inverter 92 and deposited on a transport 94 forming a part of the processor 90.
The processor 90 comprises a housing 102 adapted to be supported closely
adjacent in an abutting relationship with the printing system 9. Suitable electrical
hardware, not shown, is provided for electrically connecting the auxiliary processor
90 to the controls of the printer 9. Supported within the housing 102 is a supply
104 of white plastic sheets 106. A sheet feeder 108 may comprise any suitable configuration
for transporting the sheets, one at a time, into registry with a transparent substrate
25 received from the printing system 9. To this end, a registration member 107
is provided. In operation, a sheet 106 is fed to the registration member where
it is held until a transparent substrate 25 is positioned in superimposed registration
with the sheet 106.
Optimally, the sheets 106 which have been precoated with a clear or
a white adhesive such as clear or white toner or glue 109 (Figure 3) are fed in
the direction of the arrow 110 to a heat and pressure fuser generally indicated
by reference character 112. Under certain conditions, the glue may be omitted.
For example, when a full coverage composite image is formed on the transparent
substrate satisfactory bonding of the backing sheet 106 to the transparent substrate
25 can be effected without the use of an adhesive on the backing sheet 106. In
this instance the toner materials forming the toner image serve to adhere the members,
one to the other.
A number of adhesives can be selected for use in the present invention
including materials that will enable the layers to substantially permanently bond
to each other and not easily separate after extended time periods, such as for
up to 1 year. An example of a suitable adhesive is available from the 3M company
and is designated as 556 Bonding Film. A suitable brightener or whitener such as
titanium dioxide may optionally be added to the adhesive in order to produce a
white or near white color and, therefore, a light reflective adhesive. This bonding
film comprises 40 to 50 % by weight of polyterpene resin, 30 to 40 % by weight of
ethylent-vinyl acetate polymer, 10 to 20 % by weight of polyethylene and 1 to 10
% by weight of thermoplastic polymer. A layer of this bonding film may be applied
directly to the sheets 106 or it may be transferred thereto using a carrier sheet
containing the bonding film as provided by the manufacturer. In the case of the
latter method, the sheet 106 and the film carrier are simultaneously heated while
contacting each other for effecting transfer of the bonding film to the backing
sheet 106.
The heat and pressure fuser 112 (Figure 3) comprises heated roll members
114 and 116 (approximately 51mm in diameter) each having a heating element 118
supported internally thereof. The heating elements are controlled at their operating
temperatures (i.e. roll surface temperatures) via controls forming a part of the
IPS 12. A satisfactory roll surface temperature for each of the rolls is in the
range of 160°C to 190°C. The rolls are pressure engaged in any conventional manner
to exert an average pressure of 175 psi thereby forming a nip 119 between the two
rolls. Each of the rolls has an exterior coating 120 of silicone rubber. The thickness
of the coating on the roll member 114 is approximately 1.27mm (0.05 inch) while
the thickness of the coating on the roll member 116 is approximately 7.87mm. The
heat and pressure fuser 112 serves to form a color print 122 comprising the transparent
substrate 25, a composite color image 124 fused to the transparent substrate and
a reflective backing layer adhered to the composite toner image. In operation,
the rolls 114 and 116 move the substrates at a process speed of approximately 86.4mm.
sec-1 (3.4 inches per second). As will be appreciated, various combinations of
heat and pressure members may be employed. For example, different rubber thicknesses
could be utilized and only one roll might be internally heated. Externally heated
rolls are also contemplated.
A pair of auxiliary rolls 130 and 132 (Figures 1 and 2) positioned
downstream of the fuser 112 serve to pull the bonded members in the form of the
print 122 in a straight path away from the heated fuser rolls. The rolls 130 and
132 are operated at the same or slightly faster surface velocity as that of the
rolls 114 and 116 for effecting the pulling action noted. A heated platen 133 is
provided intermediate the rolls 130,132 and the rolls 114,116 for supporting the
simulated print 122 (Figure 3) print in a flat orientation while being pulled by
the rolls 130 and 132.
A flat vacuum transport comprising a plenum 134 and a plurality of
belts 135 serves to move the print in a flat orientation away from the rollers
130 and 132 to effect cooling of the simulated print while it is restrained in
a flat orientation by the vacuum transport. The finished print is received in a
catch tray 140 for removal or temporary storage thereof.
The white or near white backing sheet or substrate 106 may comprise
a white or near white sheet of plastic paper as described in U.S.-A-5,075,153.
As disclosed therein, the coated paper comprises a plastic supporting substrate
such as polyester rather than natural cellulose, with certain coatings thereover.
Mylar, commercially available from E.I. DuPont is preferred as the substrate for
the coated sheet 106 in view of its availability and lower cost. The coated sheet
106 has a thickness of about 0.10mm (0.004 inch). The appearance of the image can
be altered by using substrates that have different shades of white. For example,
a creamy substrate could be used for portraits, and a bright white substrate could
be used for product shots. The gloss could also be modified by changing the surface
characteristics of the transparency material either with the use of matte or silk
finish surfaces on the transparency.
The simulated print 122 comprising the transparent substrate 25, reflective
backing sheet 106 and the composite toner layer 67 have a thickness of 0.23mm (0.009
inch) which favorably compares to the thickness of a conventional color photographic
print.
The backing member 106, as shown in Figure 2, can also be obtained
using a roll 142 of backing material which is cut to an appropriate length using
a cutter 144. The roll of material may be precoated with a suitable glue for enhancing
the adherence of the backing material to the transparent substrate 25.
Alternatively, a light reflective coating can be applied over the
toner image by applying a white or near white film to the toner forming the xerographic
images on the transparent substrate. As illustrated in Figure 4, a transfer sheet
for applying the white film includes a vacuum deposited metallic film 162 disposed
upon a clear or colored polymer film 164, such as, for example, an acrylic film
like methyl methacrylate or a methacrylate or a methacrylate copolymer, which is
in turn disposed upon a polyester carrier, not shown. An adhesive layer, also not
shown, preferably covers the film 162 on the opposite side from the clear polymer
film 164. The film 162, adhesive layer polymer film 164 and a polyester carrier
together form the transfer sheet 160 that is adhered at an upper edge to a backing
sheet 172. As shown in FIG. 4, the transfer sheet 160 may be attached to the backing
sheet 172 by a piece of pressure sensitive tape 174. When the transfer sheet 160
is provided with a backing sheet 172 as seen in FIG 4, the substrate 25 is positioned
between the transfer sheet 170 and the backing sheet 172. The process of coating
a toner image with a reflective coating is more fully described in U.S.-A-4,868,049
granted to Marshall A. Nelson on September 19, 1989.
In use, the transfer sheet 160 is placed in face-to-face contact with
the receiving substrate 25 to form a sandwich with the xerographic images contacting
the transfer sheet. For this purpose an imaged transparent substrate 25 is directed
to an output tray 180 and manually retrieved therefrom. Heat and pressure are used
to cause the xerographic images to become tacky and cause the film to adhere to
the images. The transfer sheet 160 is then stripped away from the transparent substrate
containing the xerographic images 67 overlaid with the light reflective metal film
162.
Various means can be used to apply pressure and temperature in accordance
with the present invention, for example, a pair of heat and pressure rolls forming
a nip through which the sandwich is passed may be used.
The transparent substrate 25 with the toner image and the reflective
coating adhered thereto is bonded to a sheet 106 in the manner similar to that
described above in order to create a simulated photographic print in accordance
with the invention. To this end a bypass chute 182 is provided as part of the auxiliary
processor 90. A transparent substrate 25 containing a toner image coated with a
white or near white film is inserted into the chute 180 until its leading edge
is disposed in the nip between the rolls 114 and 116. Upon initiation of a print
making cycle through use of the UI 14, a reflective backing sheet 106 is fed into
the aforementioned nip such that its lead edge coincides with the lead edge of
the transparent substrate. The two members are then fed though the heat and pressure
rolls 114 and 116 and the rest of the print making elements.