Method for handling and dipping flexible belts using a spring and shaft assembly

This invention discloses a method of holding and transporting a hollow flexible belt throughout a coating process. The method includes placing a spring and shaft assembly into the hollow portion of a seamless flexible belt, and expanding the spring portion of the assembly until it is transformed into a belt carrying chucking device. The chucking device is then attached to a mechanical handling device, and the the belt is transported through the dipping and coating process. This allows the belt to be transformed into an organic photoreceptor. The chucking device and flexible belt are then removed from the mechanical handling device, and the chuck is removed from the inside of the photoreceptor.

This invention relates generally to a method and apparatus for internally 
holding a flexible belt for processing. More specifically, the invention 
relates to a spring and shaft assembly which is used to handle and 
transport a flexible belt so a photosensitive layer may be deposited onto 
its surface. 
BACKGROUND OF THE INVENTION 
Imaging members for printers and the like are typically coated by immersing 
a hollow cylinder into a stainless steel dip tank that contains a liquid 
coating solution. The cylinder is slowly withdrawn from the dip tank, to 
allow the appropriate amount of solution to remain on the surface of the 
cylinder. This will cause the desired coating thickness to be retained 
after drying. Present dipping and coating methods involve gripping the 
cylinder at one end by a mechanical handling device. 
Substrates for these imaging members are coated with at least one active 
electrophotographic layer, and can be made from rigid cylindrical drums as 
indicated above, or from flexible belts for which the present invention 
will be used. By manufacturing the substrate from a flexible belt rather 
than from a drum, the speed at which the electrostatic image is reproduced 
is dramatically increased. In addition, using a seamless flexible belt 
will eliminate problems such as seam breakage and contamination. But 
problems arise when attempts are made to coat flexible belts, rather than 
rigid cylindrical drums using known dipping and handling processes. The 
flexible belts from which electrophotographic imaging members are made can 
easily be damaged as they are handled during photoreceptor fabrication. 
Typical photoreceptor substrates are made from materials that include, but 
that are not limited to, nickel, stainless steel, aluminum, brass, 
polymerics, and paper. In order to prevent the belt from becoming damaged, 
it is best to support it along the width of its inside surface during the 
coating and drying process until the finished photoreceptor is cut to its 
final width and packaged. 
In order to conserve coating material, and to provide an internal contact 
surface for electrical grounding or biasing it is desirable to confine the 
coating to the exterior surface of the belt. This is presently achieved by 
dipping the belt such that the axis is maintained in a vertical position. 
The ends of the belt must also be sealed such that air is trapped within 
the lower potion of the belt. This prohibits the fluid from migrating or 
coating the inside of the belt. 
The following disclosures may be relevant to various aspects of the present 
invention: 
U.S. Pat. No. 5,334,246 discloses a dip coat process material handling 
system and method for coating multiple layers of material on a hollow 
cylindrical member. This system is used to produce a multi-layer optical 
photoconductive drum, and is an example of the type of system in which the 
present invention may be used. 
U.S. Ser. No. 08/508144 filed Jul. 25, 1995 by John S. Chambers et al 
pending, and commonly assigned discloses a method and apparatus for 
handling and dipping seamless flexible belts using a blow molded chucking 
device. A polymer insert is placed inside the circumference of a flexible 
belt, and blow molded to form a belt-carrying chucking device. The 
chucking device is then used to transport the belt during a dipping and 
coating process. 
Techniques for handling and dipping these substrates as they proceed 
through the manufacturing process are well known. For example, U.S. Pat. 
No. 5,358,296 discloses an apparatus and method for holding a rigid hollow 
cylindrical substrate along its inside surface. The device consists of a 
porous substance mounted upon a fluid passageway. The porous substance is 
inflated until it engages the inner surface of the substrate in the radial 
direction. The device continues to engage the inner surface of the 
substrate until a suction force is applied. 
U.S. Pat. No. 5,328,181 discloses an apparatus and method for transporting 
and coating rigid hollow cylinders. The invention consists of a mandrel 
which has an expandable disk at one end and a means for expanding the 
expandable disk at the other. The disk is expanded in a radial direction 
from the mandrel such that it comes into contact with the inner surface of 
the hollow cylindrical substrate. This results in the formation of an air 
tight seal between the disk and the substrate, and prevents the coating 
fluid from coming in contact with the inner surface of the substrate 
during dipping. 
U.S. Pat. No. 5,328,180 discloses a rigid clamp used to grip and support 
tubular objects. A linkage is attached to clamping shoes which are then 
expanded outward in the radial direction. The clamping shoes are brought 
in contact with the inside surface of the tubular object. 
U.S. Pat. No. 5,318,236 discloses a device which is inserted into a roll of 
coiled sheet material to provide support for the sheet as it is unrolled. 
The device consists of a hub assembly with an axle and two rotatable hub 
centers that are connected to support members. The support members move in 
the radial direction, and engage the interior surface of the hollow roll. 
U.S. Pat. No. 5,314,135 discloses an expandable mandrel used to mount a 
core for winding a web of sheet material. The mandrel acts as a cam which 
slides in an outward radial direction and comes in contact with the inside 
surface of the hollow core. 
U.S. Pat. No. 4,680,246, discloses a method for forming a photosensitive 
layer on the surface of a cylindrical drum by immersing the drum into a 
solution of photosensitive material. A fluid tight inflatable member is 
used to hold the drum while it is submerged in the solution. This 
inflatable member is tightly pressed onto the inside wall of the drum, and 
prevents the photosensitive solution from contacting its inside surface. 
All of the references cited herein are incorporated by reference for their 
teachings. 
SUMMARY OF THE INVENTION 
In accordance with the invention, there is provided a method and apparatus 
for transporting a flexible belt as it progresses through a dipping and 
coating process. Dipping and coating the flexible belt in the manner 
herein described will transform the flexible belt into an organic 
photoreceptor. 
In accordance with one aspect, there is provided a method of handling and 
dipping a flexible belt defining a closed loop comprising: providing a 
mechanical handling device at an end of a spring and shaft assembly, 
wherein the spring and shaft assembly includes a spring mounted to a shaft 
such that the inside surface of the spring is attached to the outer 
surface of the shaft; placing the spring portion of the spring and shaft 
assembly inside a circumference defined by the flexible belt; expanding 
the spring in a radial direction from the shaft to engage the interior 
portion of the flexible belt in sealing and carrying relationship 
therewith; transporting the spring and shaft assembly and the flexible 
belt along a path to a fluid reservoir; dipping the flexible belt in a 
fluid contained in the fluid reservoir; transporting the spring and shaft 
assembly and the flexible belt out of and away from the fluid reservoir; 
and removing the spring and shaft assembly from the interior of the 
flexible belt. 
In accordance with another aspect of this invention, there is provided a 
spring and shaft assembly for transporting and handling a flexible belt 
comprising: a shaft; a spring assembly mounted to an end of the shaft such 
that an inside surface of the spring assembly is attached to an outer 
surface of the shaft; an activator for adjusting a diameter of the spring 
assembly to engage and disengage an inside surface of the flexible belt; a 
sealing arrangement for preventing an inside surface of the flexible belt 
from being coated by a surrounding fluid; and a protrusion for attaching 
an end of the shaft to a mechanical handling device. 
Use of this invention can eliminate a substantial amount of the damage that 
presently occurs to an organic photoreceptor during fabrication. The 
invention provides an arrangement for supporting the flexible belt along 
its inside surface during dipping and coating. It will also allow the 
inside of the belt to be sealed, thereby trapping air within its lower 
portion and prohibiting the surrounding solution from migrating or coating 
the inside of the belt.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings where the showings are for the purpose of 
describing an embodiment of the invention and not for limiting same, FIGS. 
6A, and 6B depict a device used to transport a flexible belt 18 through a 
manufacturing process. The device includes a shaft 12, a detail of which 
is provided in FIG. 1, with a spring mounted at one end. 
Spring 10A, illustrated in FIGS. 2A and 2B, is one type of spring that may 
be used with this invention. As shown, spring 10A is a clock spring with 
an elastomeric gasket 28 attached to it on one side. Gasket 28 lies in a 
plane normal to the "z" axis of shaft 12 depicted in FIG. 1. 
Gasket 28 should be made from a material that can be subjected to repeated 
expansion and contraction without loosing its dimensional stability. The 
material should also be chemically inert so that it can withstand the 
vapors that are present in the organic solvents used during the coating 
process, and heat resistant so that it will not break down as the belt is 
dried. Examples of acceptable materials are filled vinylidene fluoride 
hexafluoropropylene tetrafluoroethylene copolymer (hereinafter VITON) 
which is manufactured by Du Pont, EPDM--a terpolymer elastomer made from 
ethylene-propylene diene monomer also known as EPT ethylene-propylene 
terpolymer and polydimethylsiloxane (hereinafter PDMS) which is commonly 
known in the industry. The invention is not limited to these materials, 
and other chemically stable heat resistant materials which meet these 
requirements may be used as well. 
Spring 10B, illustrated in FIGS. 3A and 3B, is another type of spring that 
may be used in this invention. As the figures show, coiled spring 10 is 
encased in a thin elastomeric coating 30 before it is attached to shaft 
12. As depicted in FIGS. 1, 3B, and 4B coiled spring 10B is mounted in a 
plane normal to the z axis of shaft 12. Like gasket 28, elastomeric 
coating 30 should be made from a chemically inert, heat resistant material 
that can be subjected to repeated expansion and contraction without 
loosing its dimensional stability. Again, filled VITON, EPDM and PDMS may 
be successfully used with this invention, but these materials do not 
represent the sole embodiments. 
The diameters of both springs 10A and 10B are adjustable, to allow for 
their insertion into and removal from the interior of the flexible belt 
18. Each can be expanded to support the flexible belt 18 as it progresses 
through a dipping and coating process. As shown in FIG. 1, gear 14 is 
present at one end of shaft 12. Gear 14 will be used to adjust the 
diameter of spring 10A or 10B. 
While only two types of springs have been described, springs with many 
different configurations may be used with this invention, and the 
invention is therefore, not limited to the disclosed embodiments. For 
convenience purposes, the invention will hereinafter be described with 
reference to clock spring 10A. Coiled spring 10B, and numerous other 
springs may used instead of clock spring 10A. Distinctions between the 
operation of clock spring 10A and coiled spring 10B will be drawn when 
necessary to accurately describe the relevant aspects of the invention. 
Illustrations which depict both embodiments are included in the enclosed 
figures. 
Spring 10A is attached to an end of shaft 12 as depicted in FIG. 4A. As 
shown, spring 10A has a cylindrical shape, and its inner circumference is 
mounted along the outer circumference of shaft 12, normal to its z axis, 
at the end opposite gear 14. The diameter of spring 10A may be varied 
throughout the use of the invention as it is necessary to support flexible 
belts 18 with different diameters. While the height 36 of any single 
spring 10A is fixed, springs 10A with different heights 36 can easily be 
manufactured to provide additional support along the width of flexible 
belt 18 when necessary. 
A flexible belt 18 for which this invention will be used is shown in FIGS. 
5A and 5B. Flexible belt 18 is the type typically used to manufacture 
organic photoreceptors that are used in electrophotographic copying 
machines. 
Once spring 10A has been mounted to the end of shaft 12, the assembly is 
placed inside the top of the circumference of flexible belt 18 as depicted 
in FIG. 6A. As shown in the illustration, shaft 12 is inserted just far 
enough into the top of flexible belt 18 to allow the top side 20 of spring 
10A to lie in the same plane as the top edge 22 of flexible belt 18. 
Gasket 28 will be located inside the top edge 22 of flexible belt 18. 
After spring 10A has been properly placed in this position, it will be 
expanded in the outward radial direction toward the inner circumference 24 
of flexible belt 18, as depicted in FIG. 7A. As spring 10A moves outward 
toward flexible belt 18, the sides of gasket 28 will become trapped 
between the inner circumference 24 of flexible belt 18, and the outer 
circumference of clock spring 10A. The remainder of gasket 18 will lie on 
the under side 32 of spring 10A at the top of flexible belt 18, forming a 
tight seal. When coiled spring 10B is used, it will be located at the top 
end of the flexible belt 18 as depicted in FIG. 6B once shaft 12 has been 
inserted into the top of flexible belt 18. The coated spring 10B will be 
expanded until its outer diameter comes in contact with the interior of 
flexible belt 18. 
Spring 10A and shaft 12 will be used to dip flexible belt 18 into fluid 38. 
During dipping, the axis of flexible belt 18 must be maintained in a 
vertical position. Immersing flexible belt 18 in fluid 38 in this manner 
will cause the presence of gasket 28 to build up an air pressure column 
inside flexible belt 18. 
When coiled spring 10B is used, elastomeric coating 30 will be used to seal 
the inside of flexible belt 18 from the surrounding fluid. Once it has 
been expanded to contact the inside edge of flexible belt 18, elastomeric 
coating 30 will form a tight seal with the top edge of flexible belt 18 as 
shown in FIG. 7B. This will cause the air pressure column to build-up 
inside of flexible belt 18 during dipping. This column of air will prevent 
the migration of fluid into the interior of belt 18, thereby allowing its 
inside surface to remain virtually free from fluid 38. 
A plan view of the expanded spring 10A is shown in FIG. 8A. Once expanded, 
spring 10A and shaft 12 can to be used to lift and transport flexible belt 
18. Spring 10A and shaft 12 assembly will then be used to transport 
flexible belt 18 as it moves through a dipping and coating process. This 
process is used to deposit a photosensitive layer onto the outer surface 
of flexible belt 18, which will transform flexible belt 18 into an organic 
photoreceptor 26. The finished organic photoreceptor may be used in a high 
speed electrophotographic imaging machine. A plan view of an expanded 
spring 10B is depicted in FIG. 8B. 
As indicated above, spring 10A and gasket 28 must expand in the radial 
direction to seal the inside of flexible belt 18 and transport it through 
dipping and coating. Expanding of spring 10A may be accomplished in many 
different ways. One apparatus which can be used to for this purpose is a 
mechanism similar to that depicted in FIG. 9. The device shown includes a 
shaft 40 which can be attached to a mechanical handling device at its top 
end. Shaft 40 also has a gear 42 attached at its bottom end which meshes 
with gear 14. Mechanical holders 16 are located near the interior surface 
of spring 10A where it has been mounted to shaft 12. These holders 16 are 
linked to gear 14 through a rod 34 which extends downward through the 
center of shaft 12. The mechanism described will be used to apply and 
remove an outward radial force at the inside edge of spring 10A. When 
shaft 40 is turned, gear 42 and gear 14 will rotate, thereby causing rod 
34 to turn. Rotation of rod 34 will move mechanical holders 16 in the 
outward direction and expand spring 10A. Shaft 40, can be turned in the 
opposite direction to rotate gear 42, gear 14 and rod 34 and thereby 
contract spring 10A. Many other methods of expanding and contracting 
spring 10A are possible, and means for accomplishing this task are limited 
only by the design of the hardware that is used in the manufacturing 
process. 
Upon completion of dipping and coating, the outward radial force that has 
been applied to the inside surface 32 of spring 10A will be released, and 
spring 10A will move inward from the inside surface of flexible belt 18. 
This will allow shaft 12 and spring 10 to be lifted from the interior of 
organic photoreceptor 26. 
An example of a manufacturing process for which this invention may be used 
to transform a flexible belt 12 into an organic photoreceptor 24 is 
depicted in FIGS. 10 through 21. 
Beginning with FIGS. 10, 11 and 12, after spring 10A has been mounted to 
shaft 12, spring 10A and shaft 12 are inserted into the top of flexible 
belt 18. Shaft 40 is then rotated to cause gear 42, and gear 14 to turn, 
thereby causing spring 10A to expand in the radial direction. Rotation of 
these members continues until spring 10A is expanded such that it comes in 
contact with the inside surface of flexible belt 18 as depicted in FIG. 
13. The top of shaft 12 is then attached to a mechanical handling device, 
and the handling device is used to transport spring 10A, shaft 12 and 
flexible belt 18 along a path as depicted in FIG. 14. Flexible belt 18 is 
moved along until it reaches the first of a series of dip tanks as shown 
in FIG. 15. These tanks contain the fluids 38 that are necessary to 
transform a belt into an organic photoconductive device. As illustrated in 
FIG. 15, the handling device is used to lower spring 10A, shaft 12 and 
flexible belt 18 into the dip tank, to allow flexible belt 18 to be coated 
with fluid 38. Once flexible belt 18 has been coated and raised from the 
coating tank as shown in FIGS. 16 and 17, fluid 38 is allowed to dry onto 
the outer surface of flexible belt 18. The belt will then be suitable for 
use as an organic photoreceptor 26. Many photoreceptor manufacturing 
processes repeat this dipping and coating sequence several times, using a 
different fluid 38 each time. 
When the photoreceptor 26 is dry, spring 10A and shaft 12 must be removed 
from the handling device as depicted in FIG. 18. As shown in FIG. 19, this 
is accomplished by rotating gear 14 in the direction opposite that 
performed above. Shaft 12 is then raised from the inside of flexible belt 
18. FIG. 20 shows shaft 12 and spring 10A after they have been removed 
from the inside of the photoreceptor 26. A typical finished photoreceptor 
26 is depicted in FIG. 21. 
Any suitable rigid or flexible substrate may be held by the apparatus of 
the present invention. The substrate may be at least partially hollow, and 
will preferably be entirely hollow, with one or both ends being open. In 
preferred embodiments, the substrate is involved in the fabrication of 
photoreceptors and may be bare or coated with layers such as 
photosensitive layers typically found in photoreceptors. The substrate may 
have any suitable dimensions. 
The present invention has significant advantages over current methods for 
transforming flexible belts into electrophotographic imaging members. Most 
notably, known means for transporting these belts through the dipping and 
coating process often require gripping them along an edge. Gripping the 
belt along the edge often causes damage to its outer surface and severely 
compromises its performance as a photoreceptor. In the present invention 
the belt is supported along its inside surface rather than gripped along 
an edge. Holding the belt in this manner virtually eliminates the type of 
damage that is regularly inflicted upon the surface of the substrate by 
conventional means. 
It is, therefore, apparent that there has been provided in accordance with 
the present invention, a method and apparatus for handling and dipping 
flexible belts using a spring chucking device that fully satisfies the 
aims and advantages herein set forth. While this invention has been 
described in conjunction with a specific embodiment thereof, it is evident 
that many alternatives, modifications, and variations will be apparent to 
those skilled in the art. Accordingly, it is intended to embrace all such 
alternatives, modifications and variations that fall within the spirit and 
broad scope of the appended claims.