U.S. patent number 3,825,724 [Application Number 05/318,322] was granted by the patent office on 1974-07-23 for wrap adjust device for controlling engagement between a web and roller.
This patent grant is currently assigned to Xerox Corporation. Invention is credited to Robert F. Allis, William Kingsley.
United States Patent |
3,825,724 |
Kingsley , et al. |
July 23, 1974 |
WRAP ADJUST DEVICE FOR CONTROLLING ENGAGEMENT BETWEEN A WEB AND
ROLLER
Abstract
The temperature of a heat sensitive web is controlled by varying
the contact area between the web and a thermo roller having an
appropriate thermo energy device coupled to it. A wrap adjust
roller is supported for movement along a circular path concentric
with the periphery of the thermo roller and varies the surface area
contact between web and thermo roller at different locations
relative to the thermo roller.
Inventors: |
Kingsley; William (Rochester,
NY), Allis; Robert F. (Rochester, NY) |
Assignee: |
Xerox Corporation (Stamford,
CT)
|
Family
ID: |
26867463 |
Appl.
No.: |
05/318,322 |
Filed: |
December 26, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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171819 |
Aug 16, 1971 |
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Current U.S.
Class: |
219/469; 219/216;
219/471; 28/185 |
Current CPC
Class: |
G03G
17/00 (20130101); G05D 23/192 (20130101); G03G
15/2014 (20130101); H04N 1/29 (20130101) |
Current International
Class: |
G03G
17/00 (20060101); G03G 15/20 (20060101); H04N
1/29 (20060101); G05D 23/19 (20060101); H05b
001/02 () |
Field of
Search: |
;219/216,469,470,471,388
;28/62,71.3 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Miller; J. D.
Assistant Examiner: Bell; Fred E.
Attorney, Agent or Firm: Ralabate; James J. Petre; David C.
Mitchell; John B.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional application of copending
application, Ser. No. 171,819, filed Aug. 16, 1971.
Claims
What is claimed is:
1. A method of controlling the temperature of a heat sensitive web
comprising
wrapping said web about a thermo roller having a thermo energy
source coupled to it to divert the direction of the web by an angle
theta,
supporting wrap adjust roller means for movement along at least a
portion of a coincident, concentric circular path around the
periphery of the thermo roller and
moving said wrap adjust roller means between at least two positions
on said circular path for varying the surface area contact between
the web and thermo roller.
2. The method of claim 1 wherein said web is positioned between the
thermo roller and wrap adjust roller means.
3. The method of claim 1 wherein said wrap adjust roller means is
positioned between the web and thermo roller.
4. The method of claim 1 wherein the radius of said circular path
is sufficient to place said wrap adjust roller means near the apex
of the angle theta.
5. The method of claim 4 wherein said radius is sufficient to
effect complete separation of the web from the thermo roller.
6. The method of claim 1 wherein said thermo energy source includes
means for heating the thermo roller.
7. The method of claim 1 wherein said thermo energy source includes
means for cooling the thermo roller.
8. The method of claim 1 wherein said web includes a migration
imaging member comprising image particles and softenable
material.
9. The method of claim 1 wherein said web includes a thermoplastic
deformation member including a thermoplastic insulating layer and a
photoconductive layer.
10. Apparatus for varying the contact area between a web and a
thermo roller comprising:
a. a thermo roller positioned to have a web wrapped around a
portion of its periphery;
b. a thermo energy source coupled to said thermo roller;
c. wrap adjust roller means supported for movement along a
coincident, concentric circular path around the periphery of said
thermo roller for varying the surface area contact between the web
and said thermo roller.
11. Apparatus according to claim 10 further including position
control means coupled to said wrap adjust roller means for moving
the wrap adjustment roller means between various positions along
said circular path to correspondingly vary the surface area contact
between the web and said thermo roller.
12. Apparatus according to claim 11 wherein said position control
device includes switching means for moving said wrap adjust roller
means to a position for completely separating the web from said
thermo roller.
13. Apparatus according to claim 10 wherein said wrap adjust roller
means is journeled in at least one pivot arm rotatably supported
about the rotation axis of said thermo roller.
14. Apparatus according to claim 11 wherein said thermo energy
source includes means for heating said thermo roller.
15. Apparatus according to claim 11 wherein said thermo energy
source includes means for cooling said thermo roller.
16. Apparatus according to claim 11 wherein said thermo roller and
said wrap adjust roller are on opposite sides of the web.
17. The method of claim 1 wherein said wrap adjust roller means is
a single roller.
18. The apparatus of claim 10 wherein said wrap adjust roller means
is a single roller.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to imaging systems and more
specifically to methods and apparatus for exchanging thermo-energy
with a web to control its temperature. The temperature control is
used to process a heat sensitive image recording member in web
form.
A migration imaging system is disclosed in U.S. Pat. No. 3,520,681
and copending application Ser. No. 553,837, filed May 31, 1966 now
abandoned, 634,757, filed Apr. 25, 1967; and 837,591, filed June
30, 1969 now U.S. Pat. No. 3,580,962 and the disclosures of the
foregoing are incorporated herein by reference. Broadly, the above
migration imaging system employs an imaging member including image
particles and a softenable material. Electric forces associated
with certain of the image particles cause the particles to migrate
through the softenable material when its mechanical resistance to
the migration is reduced. The mechanical resistance of the
softenable material is reduced by methods including softening,
heating, exposing to solvent vapors or liquids and combinations of
the foregoing. The present invention is concerned with heating and
cooling the foregoing imaging members and other heat sensitive
members in web form.
A migration imaging member in web form may be heated as part of a
development step for forming a visible image. The same film is also
cooled to lock particles at specified locations within the film.
With other heat sensitive materials, heating and cooling may serve
some other purpose. The problem in each case is how to control the
exchange of energy with a web without raising or lowering the
temperature of the web to a level at which the member is
structurally and/or functionally damaged.
Accordingly, it is an object of this invention to overcome the
above-noted problems and limitations.
Specifically, it is an object of the present invention to devise
methods and apparatus for exchanging thermo-energy with the above
referenced migration imaging member in web form.
Another object of the instant invention is to protect a heat
sensitive web from being heated or cooled to temperatures that are
structurally or functionally unsuitable.
Yet another object of the invention is to effect rapid engagement
and disengagement of a thermo-energy element with a web member.
Still another object of this invention is to control the surface
area over which thermo-energy is exchanged with a web.
Even a further object of the instant invention is to contact a web
with a thermo-energy device while the web is moving and to break
the contact when the web is stationary.
These and other objects of the present invention are realized with
novel web handling methods and apparatus. Thermo-energy is
exchanged with a web member by passing the web over a thermo roller
coupled to a thermo-energy device. A first heat exchange occurs
while the web is in contact with the thermo roller and a second
heat exchange is made when the web is separated from the roller.
The engagement and separation of the web and thermo roller is
accomplished with a wrap adjust device. The wrap adjust device
includes a wrap roller journaled in pivot arms that are rotatably
supported about the rotation axis of the thermo roller. The wrap
roller moves around the periphery of the thermo roller along a
coincident circular path. The position of the wrap roller relative
to the thermo roller determines whether the web is in contact with
the thermo roller and the amount of surface area contact between
them.
DESCRIPTION OF THE DRAWINGS
Other objects and features of the instant invention will be
apparent from a further reading and from the drawings which
are:
FIG. 1 is a schematic perspective view of an imaging system
including web handling methods and apparatus according to the
present invention.
FIGS. 2-4 are schematic side elevation views of a web passed over
wrap and thermo rollers with the wrap roller at a different
position in each figure illustrating different areas of contact
between the thermo roller and web including no contact.
DESCRIPTION
The migration imaging system of FIG. 1 employs a thermo roller 1
and wrap adjust device 2 for controlling the temperature of web 3.
Web 3 is a migration imaging structure including a conductive
substrate and a migration layer composed of image particles and
softenable material. The web is threaded through the machine
between the supply 4 and take-up reel 5. Images are formed with the
web as it is wound between the two reels by steps including:
depositing electrostatic charge on the free or outer surface of the
web as it travels past corotron 9; exposing the charged web to
electromagnetic radiation (for example, a flying light spot) as it
travels past exposure means 10; and developing the charged and
exposed web as it moves past the thermo roller by reducing the
mechanical resistance of the web softenable material to migration
by the image particles. The reduction in mechanical resistance may
be effected by several methods including the presently concerned
method of heating the softenable material.
The charging and exposing steps give rise to a latent electrical
image which is rendered visible by development at the thermo
roller. Solvent vapor and/or liquids may be used in addition to the
heat. The heating reduces the mechanical resistance of the web by
softening it. The image particles associated with the latent
electrical image migrate in depth through the developed softenable
material thereby creating positive and negative images from the
migrated and non-migrated particles. Process parameters such as
charge levels, polarities and/or materials are controllable such
that the exposed or the non-exposed particles are the image
particles that migrate. For details in regard to the migration
image process, the reader is directed to the initially referenced
Patent and Patent Applications. These references also include
disclosures relating to washing away the softenable material and to
splitting a softenable material to separate migrated and
non-migrated particles.
Thermoplastic deformation imaging processes and structures such as
disclosed in U.S. Pat. Nos. 3,055,006; 3,196,011; and 3,113,179 are
examples of other systems to which the present invention is
applicable and the disclosures thereof are incorporated herein by
reference. Briefly, the processes involve deforming the surface of
a thermoplastic material with electric fields associated with
charge deposited on the surface of the thermoplastic. Heating
and/or exposing to a solvent enables the thermoplastic to deform
under the influence of the charge. When the thermoplastic is placed
on a photoconductor, the process steps can include charging,
exposing and developing as with the migration imaging process. The
difference between the processes include those involved in the
developing step. In one developing step, particles migrate and in
the other a surface deforms.
Heating and/or cooling web members is desirable in systems other
than the foregoing. For example, a silver halide motion picture
film requires cooling to protect the resin material of the film
from heat generated by lamps used to protect the film images. In
addition, the manufacture of web members may include a step wherein
heat is applied to or subtracted from a web for diverse purposes.
The present invention finds use in all such web systems, processes
and/or apparatus.
Turning now to FIG. 1, horizontal and vertical frame plates 14 and
15 support the various system components. The drive mechanism 16 is
illustrated in an exploded position adjacent the vertical frame
plate on which it is carried. The drive mechanism includes the
electric motor 17 drivingly coupled to the take-up reel 5 and the
drag brake or clutch 18 coupled to supply reel 4. The motor coupled
to the take-up reel pulls the web 3 from the supply reel against
the bias force provided by the drag brake to maintain tension in
the web whether it is moving or at rest. The web is threaded under
the first idle roller 19 and over the image roller 20. From the
image roller, the web is threaded: around the thermo roller 1 and
wrap adjust device 2; over the exit idle roller 21; across the
display idle rollers 22 and 23 and viewing screen 24; and onto the
take-up reel 5. As mentioned earlier, the web is charged as it
passes corotron 9, exposed as it traversed means 10 and developed
as it passes the thermo roller 1.
The corotron includes a thin conductive wire coupled to a high
electrical potential source. The web substrate is conductive and is
coupled to a suitable potential, e.g. ground, through the image
roller 20. The image roller is a conductive roller electrically
coupled to ground, for example, to ground the web. The potential
difference between the web substrate and corotron wire yields a
flow of ions and other charged particles between them.
Consequently, the outer surface of the web is charged to a high
potential by the ions and other charged particles deposited on its
surface.
The exposure mechanism is illustrated schematically as a moving
pencil of electromagnetic radiation 30 that sweeps across the width
of the web. This pencil of light can be generated by any suitable
means including a beam of light reflected from the mirror surface
of a galvanometer. The intensity of the light beam can be modulated
by suitable means such as a transparency positioned in its path.
The light beam may be that generated at the face of a cathode ray
tube. Alternately, the exposure means can include a line or slit
exposure wherein a line of light replaces the pencil of light
30.
The thermo-roller includes a relatively large diameter roller
having an appropriate heating (or cooling in another system)
element within its volume. Examples of suitable thermo energy
elements include: an electrical resistance heater; and infra-red
lamp; hot or cold liquid coils; and hot or cold vapor coils. The
object is to exchange thermo energy between the web and the
periphery of the thermo roller. Most conveniently, the thermo
roller periphery is heated or cooled by conduction through the
walls of the roller. How the walls are heated is not particularly
important since this may be a matter of design convenience. For
example, radiation and/or convection may be the principal means for
heating the inside walls of the roller. However, this invention is
not limited to the methods of heating or cooling since the
invention may be practiced even when the thermo-roller is a hollow
glass cylinder having an infra-red lamp within its volume. The
primary requirement for this invention is to provide a web location
at which a highly efficient heat transfer occurs. This location is
the periphery of the thermo-roller and the wrap adjust device
cooperates to control web temperature by varying the contact area
between the web and thermo roller.
The wrap adjust device includes two pivot arms journaled at
opposite ends of the thermo roller about its axis. Member 40 is one
of the pivot arms and is typical of the other positioned at the
hidden (as viewed in FIG. 1) end of the thermo-roller. A wrap
adjust roller 41 is journaled near the free ends of the pivot arms
by suitable bearings, bearing 42 being typical. A lock nut 43 is
coupled to the axle of the thermo roller and abutts against pivot
arm 40 to hold it against rotation. When the lock nut is loosened,
the pivot arms are rotated to vary the location of the wrap adjust
roller relative to the thermo roller. With this scheme, the wrap
roller can be positioned at an infinite number of locations on a
circular path around the thermo roller. The clearance between the
peripheries of the wrap adjust and thermo rollers is selected to be
sufficiently great to prevent contact between the web and thermo
roller at least at one position of the wrap roller. The function of
web separation is discussed in more detail below.
The lock nut 43 is representative of one of many mechanisms for
controlling the position of the wrap adjust roller relative to the
periphery of the thermo roller. In more sophisticated systems, the
lock nut is replaced by a stepping motor or other position control
device. The position control device is operated automatically in
response to the movement of the web. An example, is an electrical
motor coupled to the pivot arms that is energized to rotate in a
first direction a fixed number of angular degrees when the motor 17
coupled to the take-up reel 5 is started and a fixed number of
angular degrees in the opposite direction when motor 17 is stopped.
Switching apparatus capable of such operation is well known. The
described apparatus causes the web to be pulled into contact with
the periphery of the thermo roller when the web moves and to be
pulled out-of-contact with the thermo roller when the web
stops.
FIGS. 2-4 depict the operation of the wrap adjust device except the
pivot arms are deleted for clarity of presentation. The angle theta
is the angle by which the web 3 is diverted when passed around the
thermo roller while out of contact with the wrap adjust roller 41.
The angle theta also defines the maximum contact area between the
thermo roller and web. The larger the angle theta, the greater the
amount of heat exchange occurs between the web and thermo roller
because of the greater period of time in which heat is
exchanged.
The angle theta also defines the minimum dimension for the pivot
radius 50 which is the distances between the axes of rotation of
the wrap adjust and thermo rollers. When the radius 50 is
sufficient to position the wrap adjust roller near the apex of
angle 50, a minimum contact occurs between the web and thermo
roller. Making the radius 50 even larger to position the wrap
roller to the right of the apex of angle theta, as in FIG. 4,
results in complete separation between the web and thermo roller.
The drag brake 18 coupled to the supply reel keeps the web taut
when the wrap roller is positioned at either the home position
shown in FIG. 2 or the apex position shown in FIG. 4.
If the thermo roller is heated (versus cooled), the temperature of
the web is raised when roller 41 is at the home position. The web
temperature is lowered by the ambient air when the wrap roller is
located at the apex position. The surface contact can be varied
between the two extremes by locating the wrap roller at
intermediate positions such as illustrated in FIG. 3.
The angle theta is selected for the needs of a particular system
and may be varied from zero degrees to 180 degrees. In the event
that theta is zero degrees, the web is wrapped half way around the
thermo roller and the radius of the wrap roller must be greater
than the radius of the thermo roller to obtain complete separation
between the web and thermo roller. The apex position in this case
is at infinity. When theta is 180 degrees, the contact between the
web is substantially a line at the tangent point between the web
and thermo roller. The wrap roller separates the two when
positioned at the apex of angle theta, in this case the tangent
point. Alternately, the wrap roller is positioned on the other side
of the web. In this case, there is minimum surface contact when the
wrap roller is at the apex or tangent point and the contact area is
increased when the roller is moved to another position. Since the
web is between the wrap and thermo roller, the wrap roller pulls
the web into greater contact with the thermo roller when moved from
the apex position.
Other variations and embodiments of this invention will be apparent
to those skilled in the art from the present description and
drawings.
* * * * *